·I Sir Arthur Keith

·The Anatomy of
Congenital
Pulmonary Stenosis
Sir Russell Brock
MS FR.C.S F.A.C.S (Hon)
Thorac Surgeon to Guys Hospital
Surgeon to the Brompton Hospital
CASSELL & COMPANY LTD
LONDON

·CASSELL & CO LTD 37-38 St Andrew's Hill, Queen Victoria St, London, E C.4 and at 210 Queen Street, Melbourne, 26–30 Clarence Street, Sydney, 24 Wyndham Street, Auckland, 1058 Broadview Avenue, Toronto 6, Avenida 9 de Julho 1138, São Paulo, Galeria Guemes, Escritorio 454-459, Florida 165, Buenos Aires, Haroon Chambers, South Napier Road, Karachi 2, 15 Graham Road, Ballard Estate, Bombay 1, 17 Chittaranjan Avenue, Calcutta 13, Munshi Niketan, Behind Kamla Market, 13-14 Ajmeri Gate Extension, New Delhi, PO Box 275, Cape Town, PO Box 11190, Johannesburg, PO Box 959, Accra, Ghana, Macdonald House, Orchard Road, Singapore 9, 17 Kauwlaan, The Hague, 25 Rue Henri Barbusse, Paris 5, Bederstrasse 51, Zurich 2, 25 Ny Strandvej, Espergaerde, Marne 3B, Mexico 5, DF,PO Box 189, Bridgetown, Barbados SET IN IO PT PLANTIN AND PRINTED IN GREAT BRITAIN BY BUTLER AND TANNER LTD, FROME AND LONDON F 35 ·CONTENTS 1 8 IS 23 26 29 Introduction I The comparative anatomy and embryology of pulmonary stenosis II The developing human heart III The Anatomy of the normal nght ventricle IV The ausal relationship of the pulmonary stenosis and the septal defect V The vineties of congenital pulmonary stenosis VI Pulmonary yalvar stenoses with normal Hortic root VII Infumdibular stenosis with normal aortic root VIII Pulmonary atresia, tricuspid atrosu LX Fellor's tetralogy The recognition and differential diagnosis of the type and level of the obstriction in Fallot's tetralogy XI Forms of transposition, common ventricle XII Summary Direct operations for pulmonary stenosis, physiological changes due to direct operations XIII Control mechanisms in the outflow tract of the right ventricle Reference 42 47 SI 72 86 89 98 107 Inder 10g

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·ILLUSTRATIONS 11 2 4 5 S 6 9 IO II I2 Frontispiece: Sir Arthur Kath i Diagrams to show the primitive tubular heart of five chambers 2 The heart of a skate to show the common ventricle and bulbus cordis 3 The heart of a bastang shark to show the common ventricle, the bulbus cordis and the truncus arteriosus 4. The beart of an angler fish 5 The heart of a turtle showing the two aortae, the pulmonary artery and the muscular scpta within the single ventricle 6 Prummutive tubular heart with formation of primary chambers 7 Human bart with bifid apes 8 Diagram to show the mode of formation of 2 sets of 3 semilupar valves from 4 endocardial ashions 9 Diagrum to ahow mode of dosure of ventricular septum by the bulbar ridges which develop from the pronumal part of the bulbus 10 Diagram showing that the bulbus is at first separated from the ventnde by the bulboventricular spur which later regresser so that the proximul part of the bulbuis is absorbed into the night ventnde to form part of the mfumdibulum 11 Dagnum to show the formation of the crista rupraventriculari 12 Diagram of the normal right ventride to show the inflow and outflow tracts 13 Postero-anterior englocardiogram to show the composition of the night ventride 14. Lateral angrocardiogram to show the composition of the right ventude 15 View of sheeps heart to show the way the crist1 supraventricularis KIVO us a kind of watershed to separate the inflow from the outflow tract 16 A sheeps heart from which the superficial thin investing layer of muscle fibras has been removed to demonstrate more dearly the structure of the infundibulum 17 To show the longitudıml direction of the inner layer of muscle fibres of the infundibulum 18 Thomas Peacock 19 Photograph of severe pulmonary valve stenosis vil 13 14 16 17 18 19 19 20 24 30 ·38 41 viii THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 20 Photographs of three types of pulmonary valve stenosis 30 21 Diagram to show how the outflow tract is abnormal in pulmonary valve stenosis 32 22 The effect of pulmonary valvotomy on the production or aggravation of an infundibular stenosis 33 23 Another example of change in position of the gradient from valve to infundibular level after pulmonary valvotomy 33 24 Diagram to explain the mechanism of change in level of gradient 34 25 A failed case of pulmonary valvotomy in which reference back to the operative tracing shows the aggravation of infundibular stenosis after valvotomy 35 26 Radiograph and angiocardiogram to show gross post-stenotic dilatation of the left pulmonary artery 27 Post-stenotic dilatation of pulmonary trunk 39 28 Huge heart in which the shadow of the dilated pulmonary trunk is concealed in the plain film but revealed in the angiocardiogram 40 29 Persistent foramen ovale seen in association with pulmonary valve stenosis 30. Diagram of pure infundibular stenosis 43 31 Angiocardiograms of pure infundibular stenosis 44 32 Electromanometric tracing before and after open resection of pure infundibular stenosis 33 Tissue removed at open resection of infundibular stenosis 34 Three examples of small pulmonary trunk and atresic valve 35 Example of pulmonary atresia which occurred immediately below the semilunar valves 49 36 Diagram of tricuspid atresia in which the outflow tract of the right ventricle is almost normal 37 Diagram of the normal right ventricle and of the right ventricle in Fallot's tetralogy in which are indicated the various levels at which stenosis may occur 52 38 Specimen in Fallot's tetralogy, there is a valve stenosis 53 39 Specimen in Fallot's tetralogy, there is a combined valvar and infundibular stenosis 54 40 Specimen in Fallot's tetralogy in which can be seen the raphe of fusion of the right and left septal bands to form the crista supraventricularis 55 41. Diagram to show post-stenotic dilatation of the pulmonary trunk in Fallot's tetralogy 42 Globular valvar stenosis typical of Fallot's tetralogy 57 43 Electromanometric tracing of combined valvar and infundibular stenosis 60 44 Diagram of types of infundibular stenosis 62 45 Hypoplasia of infundibulum 63 46. High infundibular stenosis as portrayed by Peacock 45 46 48 50 56 58 ·x THE ANATOMY OP CONGENITAL PULMONARY STENOSES 64 65 66 67 67 68 69 71 73 74 75 77 78 47 High infundibular stenous 48 High infundibular stenosis 49 Intermedrate infundibular stenosis 50 Angiocardiogram of interracdiate infundibular stenosis SI Speamen obtained by punch resection from patient m Fig 50 52. Low infundibular stenosis 53 Diagram to show how the obliquity of the secondary septum in low mfundibular stenosis may make punch resection from below unfavourble 54. Heart in Fellot's tetralogy to show that the ventricular septal defect may be covered by the septal cusp of the tricuspid valve 55 To show the bulge on the heart contour formed by an infundibular chamber 56 To sbow the bulge formed by un mfundibular chamber 57 Erroneous interpretation of pressure changes observed in a che of infundibular stenosis with post-stenotic chamber, assumed to be a long narrow stenosis 58 Use of ardiac atheter to localise the site of stenosis 59 Electromanometric tracing of infundibular stenosis 60 Diagrum to show interpretation of various ingrocardiographic appearances 61 High infundibular stenosis with large left pulmonary artery 62. High infundibular stenosis with rounded proximal cod 63 High infundibular stenosis 64. Combined infundibular and valvar stenosis 65 Selective angiocardiogram to show yalvar stenoses 66 Dragram to show common ventnde with a small, partly separate, right ventncular outflow truct; a low infundibular stenosis D seen 67 Resection of a segment of crista supraventriculars by means of a spur punch 68 Dugrum to show the effect of direct relief of the pulmonary stenonis m Fallot's tetralogy in correcting the night to-left shunt m addition to improving the pulmonary blood flow 69 Catheter studies before and after successful pulmonary valvotomy in Fallot's tetralogy 70 Aortic blood pressure tnang ini ase of Fallot's tetralogy after in fundibular resection 71 Blood pressure chart after a direct operation on a patient with Fallo's tetralogy sbowmg the tamponry rise in blood pressure often observed 72. Photograph of a dog's heart in which a column of water m a glass tube tied in the pulmonary artery is cousing gross distension of the pul modary valve ning end of the musculature of the mfundibulum 79 80 80 81 82 83 88 91 93 94 95 96 100 ·X THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 102 73 Diagrams to show the effect of variations in form of the pulmonary outflow tract 74 Tracing taken at cardiac catheterisation showing a single stenosisinfundibular The second tracing was taken at operation and two stenoses, valvar and infundibular, are shown 75. Mistaken catheter diagnosis of infundibular stenosis 76 Electromanometric tracings before and after pulmonary valvotomy in a case of Fallot's tetralogy to show the development of secondary infundibular stenosis 103 104 IOS ·INTRODUCTION T Haus account of the anatomy of congenital pulmonary stenosis was written in id greater part over five years ago at the time when great interest had recently been aroused in the condition and many ardiologists, surgeous, ndiologists and others were cagaged in the investigation and treatment of cuscs of pulmonary itenons Its publication was, however, deliberately delayed because I realized that with a steadily increasing experience in the management and rurgical treatment of these cases I was acqurmg much additional information Although, in the meantime, e number of account of the anatomy of pulmonary stenosu have appeared, I have not regretted this delay for the fuller experience has been of grater value The term pulmotary stetxosus laitself, of couns, not preasc, 10 this book it used as a comprehcosive term covering all verletics of obstruction to the blood flow to the lungs from congenital malformation. The individual vincties of pulmonary stenosus will be indicated by thar appropriate pemes. My Interat in the development and surgical anatomy of the condition arose from two reasons. Fint, it is more atisfactory to know why a thing occuns and It seemed obvious that there must be an explanation for the common occurrence of such a pecularly constant form of maldevelopment 18 pulmonary stenomis, even though its vincties are several. Second, my interest in the relief of pulmonary stenou by direct operation made it essential to understand the soatomical formation both of the itemonis itself and of the muscular structure of the ventricular walls in its neighbourhood. As a corollary to this it is necessary to emphasise the need for careful and complete study of the normal mortyd aatomy of a disease process when it is being investigated and treated. This remark supafluous but the fact remains that many people are handling cases of pnlmomury stenosti, including performing operations upon them, without any more than a second-hand and often rather bazy picture of the anatomical condition present. This is quite apart from the practice of making an emparc diagnosis of pulmonary stenosis and advising and performing a stereotyped operation for its Lodirect relief without attempting, at operation, to make the diagnosis of the particular variety as it is possible. The information generally available about the anatomy of the condition is, moreover commonly accepted without say personal verificaton or xudy This is obrious from the popular conception of the mature of the obstruction, especially the infundibular form. may be ·xii THE ANATOMY OF CONGENITAL PULMONARY STENOSIS In any case the introduction of such an important step as operation for the relief of pulmonary stenosis demands a reinvestigation of the whole subject and verification of past observations and descriptions What might have been acceptable as a general description for a condition which was of little interest other than as an untreatable clinical state, or as a range of congenital malformations, can be inadequate if exact surgical attack is to be based on it It is imperative in such new circumstances to re-open the whole problem and to confirm, amplify or modify the older descriptions and conceptions It is also important to realise that there may be a great difference between the anatomical state of affairs as observed after death in a specimen in a condition of muscular contraction aggravated by fixation and hardening, and the state that exists during life in an active, functioning muscular structure such as the heart The surgeon who observes at operation the condition both outside and inside the living heart will see definite and significant differences in the same specimen after death We must remember this difference between the anatomy of the living heart and the dead heart and that, in so far as this feature is concerned, postmortem examination may be deficient and misleading instead of being the acmc of truthful observation it is usually thought to be. The ordinary conception of the right ventricle is often that of a rather simple muscular structure which expands to receive blood from the atrium and then contracts to expel it In fact the arrangement is much'more complex than this, as will appear from the succeeding description The formation, structure and function of the outflow portion of the right ventricle in particular is quite complex and is of great practical importance in relation to the stenoses that affect it The general paucity of knowledge about the anatomy of pulmonary stenosis at the time of the introduction of surgical treatment was surprising because refcrence to the literature reveals a whole wealth of first-class information that is interesting, informative and even enthralling Much of this has remained neglected or forgotten and to the surgeon seeking practical information it is rather like digging and finding gold In this connection one must mention especially the writings of Sir Arthur Keith which, as always, are charmingly and simply written and full of scholarship, clear observation and deduction No one interested in the subject should fail to read the series of lectures published in the Lancet between 1904 and 1924 As long ago as 1904 Keith wrote in the introductory paragraph to his Hunterian Lecture at the Royal College of Surgeons on the evolution and action of certain muscular structures of the heart 'It is with a feeling of kccn disappointment that men who seek to extend our knowledge of the origin and development of the human heart lay down any of the standard treatises on the function and diseases of that organ Their labour as far as onc may judge from the perusal of such works lies outside the field of practical medicine and is useless to physician and physiologist alıke Keith had to wait nearly half a century to see his work on the nature and development of pulmonary stenosis bear fruit, but it is now possible to say that his observations and explanations have been of immense help in planning and ·THE ANATOMY OF CONGENITAL PULMONARY STENOSTS xtil developing a logical surgical approach to the direct operative relief of pulmonary stenosis I have to thank Professor T B Johnston for reading through my manuscript, and making numerous valuable suggestions and correcting several errors My secretary Miss Chris Jopa, has spent many tining hours on the prepare tion and scrutiny of manuscript and proofs and I am very grateful to her Sir Arthur Kath gave permission to use certain of his dugrams and also selected the frontispicce from among his several photographs, It was taken by Mr John Miller of Barnet Mesars Edward Amold and Company have given permaston to reproduce Figures I und 6 from Human Embryology and Morphology Messrs Baillière, Tindall, and Cox bere given permission to reproduce Figure 9 I am very grateful to Dr Prinzmetal for his kindness in sending mc a abort strip from one of his splendid films wluch demonstrates the peristalac-like move ments of the infundibulum. I am also grateful to the vanous colleagues who have given indispensablc ad by recording electromanometric pressure both a cardiac cathetensation and at operadon. Among these are Dr D C Deucbar, Dr R J Shephard, Dr R. Gibson, Dr P Fleming and Dr L. Brotmacher Dr Maurice Campbell has kindly allowed me to use Figure 34 from one of his utiles Figure si was first published in the British Heart Journal I acknowledge with gratitude the help to readily and woulfully given with the preparation of my of the photographs, drawings and pressure rccords by the Members of the Department of Medical Illustration of Guy's Hospital und of the Photographic Department of the Brompton Hospital.

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·CHAPTER I The comparatioe anatomy and embryology of pulmonary stenosis T 18 Concr to understand the embryology of pulmonary stenosis from a simplc knowledge of the comparative coatomy The complicated developmental -features of the human heart ure difficult to follow until it u apprecuted that in is development the heart passes through most of the stages of formation of the hart of the lower orders of animals. In fact most of the congenital malformations represent the heart, fixed as it wers, at a more primitive stage of development one that an be recognised us belonging to that commonly seen in certan of the lower orders, with the addition of adaptations resulting from the arrestod developmaat. Maude Abbott (1930) in her casual Atlas of Congoratal Cardiac Disease remarks: The most bizarre combinations of defects an usually be inter preted quite amply, u due to arly arrest of development, marked it may be by ingenious structural adaptation of growth, and Much light s cast upon the development of the matemalap heart, and incidentally, upon the period at which urrest of growth has taken place in arduc anomalies of the gTIVCT Sort by a comparative study of the adult fish, amphiban and reptilian organ. The truly att ordinary way in which those various orders in the ascending vertebrate sale mitor the succesive stages through which the humun heart pesta intrauterine hfe u one of oxture s most spectacular and impressive feats, presenting us it does a complete review of this orgio s cvolution down to the closure of the cardiac sepu m the eighth week of focal life.' very early I ·2 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS The following account does not pretend to be original; the description is entirely second-hand although illustrated by a number of comparative anatomical specimens personally collected and studied It is not possible for a pracusing surgeon to survey and verify the whole of this vast comparative and developmental problem, it is essential to rely upon the work of others. The examination, dissection and description of the human material is, however, the result of personal work. The primitive tubular heart consists essentially of five parts, the sinus venosus, the atria, the ventricles, the bulbus cordis and the truncus arteriosus (Fig. 1) It TRUNCUS BULBUS B B А. VENTRICLE ATRIUM V A SINUS VENOSUS I Diagrams to show the primitive tubular heart of five chambers and how, as the heart lengthens and becomes folded on itself, the bulbus comes to he beside the atrium and ventricle (After Keith, ‘Human Embryology and Morphology', Arnold) can be said at once that what concerns us most in the present problem is the formation and fate of the bulbus cordis. Thus Keith (1909) states one of the greatest discoveries since Peacock's time is now only dawning, but every year increases our assurances of its truth-viz that there is a fourth part or chamber in the mammalian heart which hitherto we have taken no cognisance of .. The fourth part is the bulbus cordis We have good reason for bclicying that, in the same manner as the sinus venosus has become incorporated in the right auricle, the bulbus has become included in the right ventricle, forming the part loosely termed its infundibulum’Although Keith mentions only four parts of the primitive heart, later (1933) he includes the truncus arteriosus as a fifth clement and it is really more correct to say that the bulbus is absorbed partly into the ventricles and partly into the truncus, of which it forms the pericardial part. He goes on to say, 'The credit of this discovery belongs to Alfred Greil, prosector in the University of Innsbruck. He traced the fate of the bulbus by a prolonged study of the hearts of developing vertebrates (Grcil 1903). Independently of him I had reached the same conclusion from an investigation of malformed human hearts and of the hearts of vertebrate animals A large number of the very commonest malformations of the human heart arc due to an arrest of the process ·3 THE ANATOALY OF CONGENITAL PULHONARY STENOSIS which ends in the incorporation of the bulbus cordis in the right ventride. The great majonty of cases of congenital stenosis of the pulmonary artery are of this nature The bulbus cordis is best shown in fishes, Le gill breathen, Figures 2-4 sbow examples 10 the sketc, thark and engic fish and demonstrate that it varics much m aize and shape m the different classes Quain (1929) makes some inter ating comments on it nomenclature, about which there is sometimes confusion. The memes that have been used for it are comis artmotu, bulbau arteriosus, truncoo arteriosus and bulbus cordus Walmesley in Quam s Anatomy pointed out that, conus arten su IS Dow used in human anatomy for a definite part of the right ventrice; truncus arteriosus 13 the name now usually applied in hunan embryology to that part of the common ventral vessel from which the pulmonary sorta and the proximal part of the systemic aorts are derived and the structure of whose wall, from the beginning, is that of a vessel. In the Telcostei this section of the ventral vessel is enlarged and its wall is thickened by a great development of smooth muscle and elastic usuc fibres, but it is entirely free from cardiac muscle; the name bubus arteriosus us then used for it. "The name bulbus cordes us thus the most suitable to be applied to that region wbuch as the most distal part of the heart and which yet forms the most pranmal part of the ant tube from the heart and it is to be considered a cardiac chumber for in its interior it carries the bulber valves and in 103 wall there u cardiac musde. It es present in all vertebrate embryos but in most forms if undergocs en ontological retrogression through the absorption of its propmal part into the ventricle and of its distal part into the truncus arteriosus, it remains persustent us clearly separable chamber of the heart only at the Elasmobracku Ganoids, Dipnoi and amphību. According to Waterston (1918) Langer first suggested the name bulbus cordis and it was then generally recogaised and adopted The specimens depicted in Figures 2-4 dearly show the muscle in the wall of the bulbus cordu especially Figure 3 (the heart of a beaking shark) to which the muscle is darker The tnple row of bulbar valves is also seen. The apparent constriction where the bulbus Jonas the ventricle should be poted (Fig. 2b) in view of what will be said later about constriction at the bulboventricular junction in auses of arrested fusion of the bulbus in man. The bulboventricular spur should also be noted In contrast to the large size of the bulbus cordis in the fish hart there is no reparate bulbus cordis in reprilas as is shown in the turtle s heart in Figures It is necessary to consider the reptilian heart because of other striking features which it presenu The turtie s heart shown in Figures has two atne, the nght being much larger than the left, und one common ventricle. The most strīlang feature is that three large vessels lave the common ventnde a pulmonary artery 10d two systemic cortis right which supplies the abdominal viscera and the love catremities and I left wbich supplies the head and the upper extremities.

·TRU TRUNCUS 1 S VENTRICLE cms Si 2 3 cms o z a b Thc heart of 7 skate to show the common ventricle and bulbus cordis Note the bulboventricular spur

·TAUNCUS
TRUNCUS
BULBUS
1
BULBUS
سره
VETRICLE
ATRIUM
4 The heart of an angler fish (Museum of
Royal College of Surgeons) The bulbus
formi a solid almost globular mass The
atrium and rentricle are well scen.
3 The beart of a buldng shark to show the
common ventricle the bulbus cordu and
the truncus erteriosus The continuity of
ventriculr md bulbar murcle 16 well
bown.

·6 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS LEFT AORTA PULMONARY ARTERY RIGHT AORTA the cms 2 w 5 The heart of a turtle showing the two aortac and the pulmonary artery, also the muscular scpta or trabcculac within the single ventricic Thc threc vessels cach have bicuspid scmilunar valves and as thcy arisc from the hcart are intimately connected in a firm fascial sheath As they pursue their course they undergo a clockwisc rotation from right to left reminiscent of the spiral arrangement of the embryonic swelling in the primitive truncus arteriosus Although the ventricle is single its chamber is by no means simple It is occupied by a finc sponge-like mesh and in addition is partly divided by a bulboventricular ridge into a smaller ventral chamber from which the pulmonary artcry arises and a larger dorsal chamber Thc right systemic aorta arises from the cytrcmc upper right-hand corner of this and just in front arises the left aorta The dorsal part of the ventricle is itself incompletely divided into shallow right and Icft cavitics by an obliqucly placed scptum derived from the loose muscular trabcculac of its lower wall That on the right side, known as thic caruni schosum, ·THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 7 receives the venous blood from the right atnum while that on the left, the annum arteriosum, receive the oxygenated blood from the left atrium but gives off no vesd (Abbott, 1936) Abbott states that these three arterial trunks are present together for a very short time m the human embryo, but this seems incorrect. On the other hand they provide a phylogenetic basis for Spitzer's theory of the mechanism of transposition of the great ressels In the human heart the reptilian porta is obliterated by the normal clockwise rotspion of the primitive carduc tube. Spitzer believes that various forms of transposition anse from absent or incom plete fusion. In transposition the sorte is not a transposed aorta but is a reopened nght aorta, the left beymg been suppressed. Spitzer also points out that the phylogenetic presence of a night aorta as reflected m one part of the configuration of the normal aght ventride; this is the small fossa lying between the crista supraventriculars and the antenor cusp of the tricuspid valve and which really represent the outflow tract of the reptilian right cort ·+ CHAPTER II The developing human heart 1 N describing the embryology of the human heart relevant to pulmonary stenosis it is desirable to concentrate chicfly on the outflow side to avoid making the description too complex It is not possible to adhere to this entirely since in the course of the development of the human hcart thc venous and arterial sides are brought close together The formation of the right atrioventricular orifice, for instance, is intimately concerned with closure of the ventricular septum and the development of those parts of the right ventriclc that concern us, and with the disappearance of the bulboventricular spur The primitive tubular heart (Fig 6a) undergoes irregular growth so that it becomes folded on itself to give the shape of a simple, spiralled S as shown in Figures 6b and 6c in which the primitive atria and the primitive ventriclc arc scen with the bulbus cordis and the truncus arteriosus, the bulboventricular groove should be noted From this primitive outline the final form of the heart is reached The parts about which we need to concern ourselves in this account arc (1) The formation of the two ventricles (11) The division of the truncus arteriosus into the aorta and pulmonary artcry (111) The formation of the right atrioventricular orifico (iv) The closure of the ventricular scptum (1) The incorporation of the bulbus cordis into the right ventricle 8 ·9 TULE ANATOMY OF CONGENITAL PULMONARY STENOSLS TRUNCUS BULBUS VENTRICLE ATRIUM SINUS VENOSUS C b 6 Primitive tubular heart with formation of primary chambers (After Kath) The formation of the two pentriclos According to Keith (1909c) a bifid condition of the apex of the heart is not uncommon us an abnormality in man and is a normal form in some mammals such us the dugong Figure 7 shows a bifid apar in the heart of a man who had pulmonary valver stenosis with a persistent forumen ovale. Keth rates it was difficult to give a atisfactory aplanation when the ventricular scptum was regarded an upgrowth from the floor of the primitive ventricle but, The oppoute is the case, the ventricular cavities are downgrowths or eraginations of the primitive ardiac tube, the septum being left between them during development. The upper margm of the septum thus represents a part of the lumen of the primitive haart; in the upper margin is developed the auriculo-ventricular bundle.' Borter (1953) wrta. Thus septum is really little more than the original floor of the anty periuting at its origmal level, the two subdivisions of the avity enlarging dowowards on each side of it The ventrides have become deeper and the septum proportionately higher, but that the septum has not grown upward is crident from the fact that it retains its old level of attachment to the lower atrioventricular cushion this level is original and persistent throughout Keith, after mentioning the auriculo-ventricular bundle developing in the upper morgin of the septum goes on to say, In malformed harts the bundle has a definite relationship to the interventncular forumen. On the right septal wall the bundle begins in the node atuated behind the tendon of the septum und passes forwurds on the lower margin of the foramen. The cract relationship of the atrioventricular bundle to the septal defect and to the other structures in the right ventncular outflow truc (mfundituluom) obviously of great practical importance when intraardiac surgery is being planned ·THE ANATOMY OF CONGENITAL PULMON IRY STENOSIS Cms 2 3 7 Human heart with bifid apex (11) The division of the truncus arteriosus into the aorta and the pulmonary arı The truncus arteriosus, the single vessel that conveys blood from thc prii tive heart, is divided into its two final components by the devclopment of i prominent ridge-like thickenings of its endocardial lining, these ridges, the si and left spiral ridges, fuse to form thc aortopulmonary scptum which divides i unabsorbed part of the bulbus into an aortic and a pulmonary trunk Below : spiral scptum four cndocardial cushions form in the distal part of thc bull cordis ncar its junction with the truncus, the right and left cushions fusc logeti to form a scplum (the distal bulbar scptum) with which the spiral scptum fus thus further completing the division between the aorta and thc pulmonary arte at the same umc thc tho sets of 3 scmilunar valves de clop from the origini. cushions (Fig 8) ·11 THE ANATOLTY OF CONGENITAL PULMONARY STENOSIS 8 Durgrim to sbow the mode of formation of 2 sets of 3 semi lumat velve from 4 endocardial cunhtoas. () The formation of the night atrieteninaular orifice The angulation of the primitive heart tube brings the utenal and the venous components close together so that the formation of the two atrioventricular onfices is indmately associated with the closure of the ventricular septum and the development of the infundibulum. Two endocardial cushions (a ventral and a dorsal) form in the primary atrial canal, these cushions fuse and form the septum intermedium, thus separating the nght from the left atrioventricular orifice. The ventricular septum reaches both the ventral and the dorm endocar dul cushions making a free falaform edge between them below the septum mtermedrum. It meets the dorsal endocardial cushion near its right extremity (ro) The closure of the ventricular septum The description has so far provided for two ventricles still partly connected above by a foramen which represents the lumen of the primitive heart Above this foramen the truncus arteriosus bas been divided to give the two great vessels with their semilunar valves, and behind it are the two atrioventncular anifices The closure of the ventricular foramen und the joining up of these somewhat diverse parts 18 accomplished chiefly by the right and left bulbar ridges, which form the prorimal bulbar septum, and which develop m the walls of the bulbus below the dutul bulbar septum, these two structures are of great importance to an under standing of the anatomy of the musculature of the normal and malformed right ventnde. The two bulbar ridges (pranmal bulbar septum) fuse above with the dista] bulbar septum, which has already been mentioned us fusing above with the right and left arterial cushions, the separation of the pulmonary from the aortic orifice b thus continued further downwards. The night bulbar ridge grows towards the left across the right atrioventricular orifice and just reaches the attachment of the ventricular septum to the dorsal eodocardial ashion. The left edge, in contact from its eady stage with the upper part of the septum, begins extending along the free margin of this (Frazer, 1931) In thu Fay the left ddge reaches the night ndge by growth along the edge of the ventncular forumet, and by fusion between the two ndges the cortic channel is roofed to and entrely separated from the pulmonary channel (Fig 9) The final closure of the forma como from a downgrowth of a small portion of the dorsal ·12 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 2 pa & pa do 6 2V. ys Tuntil pulm a 2ort ܝܐ 1 9 Diagram after Frazer to show mode of closure of ventricular scptum by the bulbar ridges which develop from the proximal part of the bulbus (infundibulum) pa Pulmonary artery VS Ventricular scptum ao Aorta av Right atrioventricular a and b Bulbar ridges valve 1, r and v Left, right and ventral bulbar cushions which develop from the dista? part of the bulbus (the arterial root) and form, with the dorsal cushion, the aortic and pulmonary valve cusps endocardial cushion, this is the pars membranacea septı. This also intervenes between the right atrium and the left ventricle, 1 c. it is in part an atrioventricular septum. (v) The fusica of the bulbus cordis into the right zentricic Figure 101 shows diagrammatically the form of the embryonic human heart in the fourth weck, Figure 10b depicts how by the third month the bulbus cordis das been incorporated into the first part of the truncus and into the wall of the right tentricic to form thc infundibulum As can also be seen a small part of the bulbus is incorporated in the subvalsar part of the left ventricle and may be responsible for the maldei clopment known as congenital subaortic secnosis. For the purposes of this monograph this part of the bulbus which fuses with the Icft vcnincle still henceforth be ignored ·13 THE ANATORTY OF CONGENITAL PULMONARY STENOSIS AT AT RV LV RV a 10 Diagram after Kelth showing on the left-hat the bulbus is at first sepurited from the ventricle by the bulboventricular spur (in black) Later the spur regretses so that the proximal part of the bulbus is absorbed into the right ventricle to form part of the Infundíbulum-hown on the right. Waterston (1918), in discussing the part played by the bulbus cordus in the formation of the night ventnde, states 'Perhaps the most strilang change is the dilatation of the channel leading to the pulmonary artery Up to the 125 mm. stage the lumen was DATTOW and inconspicuous Now it u large and dilated and the orifice into the polmonary artery is placed upon the dorsal wall, not at the termmation. The ventral wall is hned with a reticulated formation of muscle continuous with that of the ventricle 'Thus the infundibulum of the right veninde u formed from a portion of the bulbus cordis end us at first merely a DATOX channel but becomes distended. In the process of development of the ventricle the prominent bulboventricular spur to begin with cuses the opening of the bulb to lad out of the right atrenity of the ventricular avity Later this spur becomes less and less prominent due to atrophy and disappannce of the dorsal and left wall of the bulbus until eventually the whole left and back wall of the bulbus bave practically disappeared (Frazer 1931) The chamber of the bulbus cordis, separate at an early stage, become overwhelmed by the musculature of the ventndien it is not obliterated but is incorported us un intrinsic part of the ventricular system. Kath (1924) states that 'the muscle cells of the developing heart have power of mvasion of spreading into and occupying endocardial tissue masses and of grouping themselves into elabor ate formations In an earlier lecture (1904) he describes how the closure of the ventricular foramen is due to development of a great band of musculature which s characteristic of the mammalian right ventride and of which no notice has been taken When the septal wall of the infundibulum of the right ventnde is tramined there will be observed a muused, wide flat band of muscle fibres wluch ·14 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS II Diagram after Keith to show the formation of the crista supraventricularis by fusion of the right and left septal bands end in the base of the aorta That band is well known in the reptilia in which it is attached above to the septum between the orifices of the aorta and pulmonary artery. ... It separates the arterial from the venous blood during systole of the repulian ventricles 'This arrangement has already been described in the turtle's heart in Figure 5 and the reason for mentioning these muscular ridges within the single reptilian ventricle becomes clear when it is realised that they are significant in relation to the developing mammalian heart Keith (1924) describes how the musculature of the developing right ventricle contains two large septal bands (the right and left, a and b in Fig 11) which invade and occupy the endocardial cushions of the night and left bulbar ridges The two bands unite to form the muscular structure known in the fully formed heart as the crista supraventricularis. An irregular linear raphe can be seen where these bands fuse, this line is only poorly shown in the normal heart but can sometimes be recognised in a malformed heart such as that shown in Figure 40 (p.55) which is from an example of Fallor's tetralogy The two muscular bands are continued from the crista supraventricularis along the right lateral and the septal wall of the right ventricle, in a manner to be detailed later, in such a way as to form a muscular constriction at the junction of the body and infundibulum of the right ventricle, a fact to which Peacock drew attention (1886). He pointed out also that it indicated the mode in which the right ventricle is developed, as illustrated in the heart of reptiles such as the turtle with its single ventricle imperfectly separated into three compartments by muscle ndges In systole this muscular constriction becomes more pronounced and indicates how, if some failure of expansion or imperfect inclusion of the bulbus cordis occurs, an obstruction can, and in fact does, occur at this lovel ·CHAPTER III The anatomy of the normal right ventriclo EFORE describing the details and varieties of pulmonary stenosis it 19 necessary to describe the structure of the normal right ventricle which is consists esscatally of two portions, an afferent inflow or atral part into which the atrioventricular onfice leads, and an efferent or outflow part which leads into the pulmonary artery The first part is sotaetimes called the simus and the second part is the infundibulum (Fig 12); they are normally separated by the muscular ring mentioned above wtuch us formed by the artista supraventricularis and its continuations leadmg finally to the moderator band. The formation of the night ventricle is also displayed in the postero-anterior und lateral angiocardiograms shown in Figures 13 and 14 The filloag defect caused by the downward projection of the wodge like insta supraventriculans us clearly seen in Figure 13 The key to Imderstanding the oght ventricle is the crista supraventriculans, thus important muscle mass is depicted in Figure 15 which is a dissection from a sbeeps heart. It is also seen in Figures 38 and 40 It forms a thick prominent ndge which projects down between the inflow and outflow portions of the ventride. Its formation by fosion of the nght and left septal bands was shown diagrammatically in Figure 11 and this arrangement is dearly indicated in Figure 40 (p 55) To ito nght side the crista supraventriculars is continued on the anterior wall IS ·16 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 12 Diagram of the normal right ventricle to show the inflow and outflow tracts INFLOW OUTFLOW of the right ventricle towards the right border of the heart, its main branches run along the base of the ventricle on the lateral margin of the right atrioventricular orifice In systole it helps to draw the lateral against the septal wall of the ventricle and forms part of a safety-valve mechanism of the tricuspid orifice (Keith, 1904c) On the left the muscle sweeps as a wide band down the septal wall to end in the trabecular muscle of the apical region, the moderator band is part of this musculature and serves to bind it to the anterior papillary muscle The exact relations of the moderator band to the papillary muscle and their embryological significance are discussed by Mall (1912), who states that according to its development it should end in the site of origin of the anterior papillary muscle The right limb of the atrioventricular bundle passes down the septum and along the moderator band and Keith (1924) states all of the right ventricle which lies above the main atrioventricular bundle and in front of its right branch is bulbar or infundibular in origin' Behind the septal end of the crista supraventricularis and between it and the anterior cusp of the tricuspid valve is a small recess of variable depth which, although apparently insignificant, is of great developmental interest as it may, perhaps, represent the outflow channel of the right reptilian aorta The infundibulum (Latin–funnel) stands out as a funnel-like portion of the right ventricle as can be seen when it is viewed from above, after removal of the atria (Fig 16) In this specimen the formation has been thrown into greater prominence by removing the superficial encircling fibres which enclose both ventricles This leads us to a consideration of the arrangement of the muscle fibres of the anterior wall of the infundibulum The superficial fibres consist of transverse loops which continue over both ventricles When these are peeled off a layer of transverse fibres is seen encircling the infundibulum alone (Fig 16) On the inner aspect of the infundibulum the fibres run longitudinally (Fig 17), this obeys the general rule pointed out by ·17 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS C Outflow Right atrium Inflow 13 Postcro-interior mglocardiogrum to show the composition of the right ventricle Ludwig (1849) that each piece of the venuncle which possettes the entire thick non of the wall has a system of fibres on it outer surface and a system at approx imately nght angles to it on its inner surface; and between them a series of layers in a regular succession of transition of direction from the one to the other (Quen, 1929). This arrangement is of considerable practical significance in regard to the direction of surgical incisions into the anterior wall of the infundibulum If a longitudinal incision is made the more superficial, arcular fibres arc cut across transversely and tend to gape On the other band the inner wall is cut in the direction of its fibres and ben the Found 3 sutured there is no tendency to gape Scrutiny of the inner wall of the infundibulum after a longitudinal incision ·18 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS Outflow Inflow 1 14 Lateral angiocardiogram to show the composition of the right ventricle. has been sutured reveals that the line of closure is almost invisiblc, a finc, firm scar results and thrombus formation is minimal or absent If a transverse incision is made there is definite gaping along the inner surface of the suture line and inspection of the wound 7-10 days later in the heart of an experimental animal shows an obvious line of granulation tissue marking the irregular furrow There is no question, therefore, of the desirability of using a longitudinal incision in the anterior wall of the infundibulum It is opportune here to mention briefly the question of nomenclaturc, about which there is often confusion Some mention has already been made of it in regard to the term bulbus cordis The crista supraventricularis (BNA) according to Walmcslcy was first

·OUTFLOW
CRISTA
INFLOW
15 View of sheep heart to show the way the criste supraventricularls serve us a
kind of watershed to separate the inflow from the outflow tract.
Cms
cms
2
2
3
16 A sheep a heart from stuch the superfidal thin inverting layer of muscle fibres
has been removed to demontrate more clearly the structure of the infun
dibutum. The stria have been removed.
с

·20 THE ANATOMY OF CONGENITAL PULMONARY STENOST: 17. To show the longitudinal direction of thi inner layer of muscle fibres of the infundibulum cms 2 3 4 accurately described by Wolff (1871) and although not definitely named by him, is usually called éperon de Wolff by French writers, Pettigrew names it the 'fleshy pons' and Sappey, Cruvelhier, and See the muscle compresseur de la valvulc tricuspidale' (Quain, 1929) It should be noted that Keith does not use the term but describes the muscle mass as being formed by the two septal bands which hc describes as 'a' and 'b', although Quain identifies Keith's band 'b' as being presumably the same as the crista supraventricularis Quain also states that Wolff applied the term conus arteriosus to the arterial part of the right ventricle, a term which is still much used today although often loosely and vaguely in relation to a 'conus area', identified radiologically, which includes portions of the heart not certainly identifiablc as this part of the righi ventricle and which are not infrequently something entirely different, such as the pulmonary artery or the left auricle The term 'infundibulum', according to Quain, was first used by Sappey, Cruvelhier and Poirier, Séc names it thc pulmonary canal Infundibulum is preferred in this book and will be used throughout in preference to conus arteriosus Structure of the arterial root Before leaving the anatomy of the right ventricle it is important to draw attention to the account in Quain (1929) of the structure of the 'arterial root', the ·21 THE ANATOMY OF CONGENITAL PULMONARY STENOSLS derivative of the distal part of the bulbus cordis, As it is relevant to some of the more distal malformations in this region Quain states that at each of the arterial openings there is a short tubular zone formed of fibrous tissue, the proximal borders of which, at the junctions with the ventncular muscle and with the typial artenal wall, are uneren. This zone is a deanaive of the bulbus cordis, as are also the semilunar valves which are formed on its inner surface Since the valves are derived from the prommal ends of the distal bulbar swellings, it follows that the part of the fibrous zone which lies between the attachments of the valves and the lower end of the typical arterial wall is derived from the distal part of the bulbuis, the inregulanty of its distal margin is due to the uneven advance of the arterial wall into the bulbus wall The put of the fibrous zone which lies proximal to the valves is the rudiment of the ventricular part of the bulbus, the muscle tissue of which has diappeared, the proximal part of it u induded in the heart and covered with ventricular muscle, but the boundary between the two parts is irregular on account of the irregular distal excursion of the ventricular muscle. 'The boundary between the ventricle and the arteria, in the functional sense, 13 aasily defined us the line of attachment of the semilunar valves It will be apparent, however, from what has been mod above, that the morphological boundary by no means corresponds to the functional boundary that the ventricle cannot be considered to extend upwards us the spatia mtaroaloularia nor the urtery to extend downwards as the sinuses of Valsalya. Henle was the first to draw attention to thu difficulty of defining the ventriculo-arterial boundary and introduced the term arterial root" (the fibrouss zone mentioned above) to replace the term arterial angs by which this boundary had been previously defined, and be described the unevennes of the margin of the ventricular musde in a general way that it reaches highest in the spatia intervalvularia and that at certain places it reaches above the valve attachment. Luschla, however, was the first to describe the fibrow zones and their connections in detall 'The wall of the sinusas of Valuava then, consists in part of the arterial wall md, at a virylog distance below this, of the fibrous time of the urterial root", in which there is little or no elastic tissue, and which is continuous with the fibrous tiasuc of the cusp of the valva at their insertion and with the fibrous tissue of the ventricular musculature At the transition of the utery into the artenai root the clastic tissue of the arterial wall becomes gndually less and ends in a pointed projccuon which lia close to the intimal coat "The level of the line of transition from the urtery to the uterial root us the Hande in all three sinutes of the pulmonary artery, the distance between the valve attachments and the arterial wall being the greatest at the middle of the sunses, where it is about one third of the length above the cusp or maryln und least at the udes The upwurd extension of the ventncular musculature is greatest in the left sinus of the pulmonary artery the greater part of the asp at this anus being attechied to muscle tissue; in the posterior pulmonary sinus the musculature reaches just to the stuched bands of the cosp, while in the aght daw it reaches ·22 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS a little beyond it Langer has stated that in the child the attachment of the cusps is higher and is surrounded by ventricular muscle These rather long extracts have been quoted because they introduce and describe an anatomical and embryological matter of great relevance to the malformation of this region If it is a true hypothesis that the stenouc lesions arise from some imperfect development of the bulbus cordis, then it is just as important to know the distal limits of this structure and its level of junction with the truncus arteriosus as to know its proximal connection with the right ventricle since the distal part of the bulbus is absorbed into the truncus In this lies the explanation of pulmonary valve stenosis and of the forms of pulmonary atresia affecting the beginning of the pulmonary artery The various malformations known collectively as pulmonary stenosis will be dealt with in the next chapter Before passing on to this it is as well to summarise the main argument and conclusions in connection with the embryology and surgical anatomy of the right ventricle Summary The right ventricle consists of two portions, a proximal or inflow portionthe sinus, a distal or outflow portion--the infundibulum Between these two parts is a muscular constriction formed, in the roof, by a large projection, the crista supraventriculars; important connections pass from this to the right wall and to the septal wall and so down to the apical musculature The infundibulum is developed from the bulbus cordis which, first of all a narrow passage, cnlarges or expands and is then overwhelmed by a growth of the ventricular muscle into it. The stage of formation of the bulbus cordis and its fusion into the right ventriclo and the truncus arteriosus is seen for a short time in the human embryo A wellformed bulbus cordis is a normal constituent of the heart of the gill-breathing fish. Distally the bulbus tissue forms the pulmonary valves and first part of the pulmonary artery, the so-called arterial root The development of the infundibulum and the inclusion of the bulbus cordis is intimately concerned with the closure of the ventricular septum It remains to be shown how the majority of examples of malformation associated with pulmonary stenosis are due to some abnormality of the expansion, development or fusion of the bulbus cordis ·CHAPTER IV The causal relationship of the pulmonary stenosis and the septal defect B EPORE descobmg the various types of pulmonary stenosis it 18 as well to discuss the question of the relative significance to each other of the sepul defect, the destroposed Lotte and the pulmonary stenosu, in other words, which is likely to be the primary lasron? Peacock (1866) has discussed this matter in an interesting and Informative manner Fallot's clinical description of the malformation unociated with bu numc Free wntten some 22 years later (1888), and it will be seen from the following description that he was intiapated by Peacock who writes, In one of the most interesting fomus of anomaly the devlation of the septum u to the left, so that the right ventrcle us of large size, and the torta arises wholly or in part from that avity ud this condition is most generally associated with obstruction to the passage of the blood from the night ventricle. He then discusses which is the likely primary lesion and his remarks are so pertinent that they are best quoted in full a step which has the additional ment of mrlong some catre acknowledgement to the value of his contribution. After pointing out that Meckel frvoured the septal defect and displacement as the pnmary lesion whereas William Hunter (1812) thought the pulmonary obstruction to be the exciting cause, he agrees with Hunter and continues, Humter pointed out that if duong carly foctal life when the interventricular septum is incomplete some obstrocon erote by which the right ventriclc become incapable of freely transmitting the blood which 23 ·22 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 3 a little beyond it Langer has stated that in the child the attachment of the cusps is higher and is surrounded by ventricular muscle These rather long extracts have been quoted because they introduce and describe an anatomical and embryological matter of great relevance to the malformation of this region If it is a true hypothesis that the stenotic lesions arisc from some imperfect development of the bulbus cordis, then it is just as important to know the distal limits of this structure and its level of junction with the truncus arteriosus as to know its proximal connection with the right ventricle since the distal part of the bulbus is absorbed into the truncus In this lies the explanation of pulmonary valve stenosis and of the forms of pulmonary atresia affecting the beginning of the pulmonary artery The various malformations known collectively as pulmonary stenosis will be dealt with in the next chapter Before passing on to this it is as well to summarise the main argument and conclusions in connection with the embryology and surgical anatomy of the right ventricle Summary The right ventricle consists of two portions, a proximal or inflow portion the sinus; a distal or outflow portion—the infundibulum. Between these two parts is a muscular constriction formed, in the roof, by a large projection, the crista supraventricularis; important connections pass from this to the right wall and to the septal wall and so down to the apical musculature The infundibulum is developed from the bulbus cordis which, first of all a narrow passage, enlarges or expands and is then overwhelmed by a growth of the ventricular muscleinto it The stage of formation of the bulbus cordis and its fusion into the right ventricic and the truncus arteriosus is seen for a short time in the human embryo A wellformed bulbus cordis is a normal constituent of the heart of the gill-breathing fish Distally the bulbus tissue forms the pulmonary valves and first part of the pulmonary artery, the so-called arterial root The development of the infundibulum and the inclusion of the bulbus cordis is intimately concerned with the closure of the ventricular septum It remains to be shown how the majority of examples of malformation associated with pulmonary stenosis are due to some abnormality of the expansion, development or fusion of the bulbus cordis ·CHAPTER IV The causal relationship of the pulmonary stenosis and the septal defect EFORE describing the various types of pulmonary stenosis it 18 as well to discuss the question of the relative significance to each other of the sepul which us likely to be the primary lanion? Pencoct (1866) bus discussed this matter in an interesting and informative manner Fallot's clinial description of the malformation associated with his name was written some 22 years later (1888), and it will be seen from the following description that he was antiapated by Peacock who wita, In one of the most interesting forms of anomaly the deviation of the septum u to the left, so that the aght ventnde is of large size, and the sort anses wholly or in part from that avity, and this condition is most generally associated with obstruction to the passage of the blood from thc nght ventncle' He then discusses which is the likely primary lesion and his remarta are so pertincat that thcy are best quoted in full a step which has the additional merit of making some catre acknowledgement to the value of his contribuon. After potting out that Meckel favoured the septal defect and displacement us the primary lesion, wheraus William Hunter (1812) thought the pulmonary obstruction to be the crating aube, he agrees with Hunter and continues, 'Hunter pointed out that if dunng early foetal life when the interventricular scptum pus incomplete, some obstruction arose by which the nght ventnde became incapable of freely transmitting the blood which 23

·--
+
}
-
-
18 Thomas Peacock

·THE ANATOMY OF CONGENITAL PULMONARY STENOSLS 25 it contained through the pulmonary artery into the ductus artenosus and descend ing aorta, the current must necessarily pass through the aperture in the septum into the left ventricle and thus the final separation of the two avioes would be prevented To those views it is scarcely possible to object and it seems equally to result from them that the reptum in its further growth might be made to deviate to the left, so that the norte would communicate with the right ventncle It also follows that from the connection between the aorta and the right ventride, the constant flow of blood from the canty into the vessel must tend to drw the aortic onfice still further to the nght, so as to produce widening of the aperture and of the ascending porta which is so peculiar a feature in all those auses in which that vessel had a double ongin from the two ventricles Meckel suggests that incompleteness and displacement of the septum art phmluve defects, and that in consequence of the blood finding a ready outlet from the right ventricle through the aorto the pulmonary artery becomes more or less abortive, and the onfice is contracted down during the progress of development. This view however throws no light on the mode of formation of those very much more numerous cases in which, with the diminution in the capacity in the orifice and vessel the valves of the pulmonary artery are seemingly discased. It leaves also the nature of the onginal defect una planed, and subsututes for what appars in many cases an obvious and suffiaent anise, an caturely theoretical idea.

·CHAPTER V The varieties of congenital pulmonary stenosis C LASSIFICATIONS are apt to recoil on the head of their author, cspccially when knowledge and experience are incompletc However, it is necessary to attempt some logical arrangement, if only to make description and discussion casier The classification and comments that follow arc provisional and dependent on present experience The varicties of pulmonary stenosis to be discussed arc (1) Pulmonary valuar stenosis with normal aortic root a. with closed atrial scptum b with intcratrial communication (11) Infundibular stenosis with normal aortic root (111) Pulmonary atresia a artcrial atrcsia b valvar atrcsia (10) Tricuspid atresia (v) Fallot's tetralogy a valvar stcnosis 26 ·27 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS infundibular stenosis C. combined valiu ind infundibular stenosis dreptul defect () Aorta and pulmonary artery both ausing from right ventricle with pulmonary stenosis, and septal defect (0) Transposition of the great Dessels, with pulmonary stentosus (ru) Common tentacle auth pulmonary stenosis, fusion of inflow portion of nght ventricle with left veninde, semi yatigial infundibulurn. This monograph is concerned primarily with a description of the anatomy of the various typos of pulmonary stenosis, but such a description is enhanced by reference to radiological and dinical features and to operation findings The need for an anatomical description rests on clinical application and it is therefore timely to say something of the recognition of the vanous types of stenotus This does not imply a full clinical description and differential diagnosis but merely some general remarks on the problem. In most types a firm diagnosis can be made before operation by consideration of the dinical features, physical signs, electrocardiography and the full range of radiography, including angiocardiography; ardiac catheterisation increases yet further the extent of preoperative diagnosis But even with these aids and with considerable practical openence it may bull be difficult or impossible to make a firm or complete dugnosus before operation Moreover, it may not be desirable or worthwhile to apply all the available tests n order merely to obtain a complete anatomical diagnosis Thus, in most cases of Fallot's tetnlogy, of the basic diagnosis is acceptable, it is but rarely Decessary to use ardiac catheterisation and inglocardiography to try and ducidate the exact site and type of the stenons Once the need for operation has beca accepted the opportunity for maldng a precise anatomical diagnosis will present when the heart is aposed u thoracotomy The direct information obtained will be much more suct than that offered by indirect preoperative methods The actual plan of operation is not affected by the type of stenose even if this is known beforehand In cases of presumed pulmonary stresu It is only at operation that the counct observations can be made that decade whether or not a palliative operation 18 possible, In other word, exposure and cumination of the living heart is the best final method of obtaining a diagnosis In most cases it is superior to post-mortem study for, although the total axposure at autopsy may permit i more complete camination of some parts of the heart, post-mortem crimination, in general, suffers from the grave disadvantage that it is done on a dead structure which is often in ngor mortis, may be hardened by formalin, and frequently deformed or distorted in the process of fixation. This is the main reason why so much of ·28 THE ANATOMY OF CONGENITAL PULMONARY STEXOSIS what has been written and taught about pulmonary stenosis is inaccurate and misleading When the heart is exposed at operation, with the pericardium opened widely, much can be learned by inspection, palpation (both external and internal), by insertion of instruments and by electromanometric measurements made in the various chambers and vessels both by needle puncture and by catheter As will be shown in the following descriptions it is possible to make a full diagnosis of the site, nature and severity of the pulmonary stenosis except in rare cases We have, in fact, another example of the great advantages of a study of the pathology of the living ·CHAPTER VI Pulmonary valvar stenosis worth normal aortic root (synpure pulmonary stenosis , 'Trilogy of Fallot) 1 SE term Trilogy of Falloť u popular in the French Literature but is imperfect, not entirely satisfactory 18 pure pulmonary stenon which, though a convenient term to indicate absence of ventricular septal defect and an over riding corta, fails in those cases in which there a communication between the atru. Allenby and Campbell (1949) have given a valuable report on the condition, its operative treatment bas been dealt with by Campbell and Brock (1955) and by Milstan and Brock (1955). A few years ago it was thought to be a ranty but now that the diagnostic features have been recognised it u accepted as fairly common. Thus Campbell (1953) in an udslysus of 1 100 cases of congenital heart disease ut hus clinic found that 103 frequency was about equal to that of persistent ductus arteriosus The oalour abstruction The basic feature of the stenosis by fusion of the cusps of the pulmonary valve to form in obstructing membrane which under the influence of the nght ventricular pressure, projects u a dome-shaped or conical structure into the pol monary artery the cauct shape is doubtles influenced by the thickness of thinness, 29 ·19 Photograph of severe pulmonary valve stenosis The very dilatcd pulmonary trunk has been opened to display the obstrucung valve domo a b 20 Photographs of three types of pulmonary valıc stenosis (For details "cc (CIP) ·THE ANATOXTY OF CONGENITAL PULMONARY STENOSIS 31 ngrdity or suppleness of the fused valve cuesPS Although it is natural for the obstructing membruoc to become thicker and more ngid as the years advance, it may be found to be short, thick and ngid even in children. In older patients small warty vegetations are often found around the small central onfice on the arterial aspect, occasionally the apex of the valve cone is lightly calafied. The lumen, m extreme cases, may be no more than 2-3 mm in diameter (Fig 19), and it remartable that hfe can continue when it is realised that the whole of the arculating blood has to pass through such a tiny aperture. The lumen may, in milder cases, be us much us O-5-1 cm. In diameter It is generally possible to recogare the three cusps and their fused commissures (Fig 200 and b), occasionally the distal surface 13 smoothed out with no trece of the ausps (Fig 200) It is still often stated that the fusion of the cusps 18 due to focusi endocarditis , 1 conveniently vegue term which could be accepted if it definitely included non bacterul processes The chief difficulty in understanding valvar stenosis developmentally has been the apparent fusion of three well-formed cusps ha a hart in which the development of the ventricular septum has been completed. Clearly it has occurred much later than the malformation in Fallot's tetralogy which paust date from before the heart is fully formed Kath states 'under the microscope the valves are seen to be composed of dense laminated fibrous tissue at their margins, but the body of the valves shows a reticulated tinue distinctly embryonuc in character It is not mrcasonable that such a valvur obstruction an occur as a predominant feature in a maldevelopment of the distal part of the bulbus cordis, from which it should be remembered, the valves develop The speamen in Figure 356 49) is of great interest in this connection for, although from AD couple of pulmonary atrexa, it shows the valve cusps are well formed but fused and there is complete obliteration of the channel immediately below them, the rentacular septum is fully formed. The closure of the ventncular septum depends upon the development of the more prosamal connections of the bulbus cordis and it is not difficult to accept that the valves should be malformed and yet the rest of the structures developed from the bulbus cordis show only slight abnormality The right vxnircle Abnormality of the other structures developed from the bulbus cordu although slight, are however important for cxamination of the night ventnde in these cases of pure pulmonary valyu stenosis reveals aigmficant feature which dearly indiate the condigon is in aarber developmental one rather than a later acquired state. In addition to the river fusion, the infundibulum is smaller und aborter than it should be, wually the infuodibular lumen, even though smaller, is adequate cicept in the arcumstance to be dacabed later Morcover the infundibulum ·32 THE ANATOMY OF CONGENITAL PULMONARY STEXOSIS exhibits the same 'icing' lining of thickened opaque endocardium scen in frank infundibular maldevelopment as in Fallot’s tetralogy. Today it is customan to dignify this state by such terms as 'endocardial fibroelastosis', etc. Again, although the lumen of the pulmonary artery above the valve is always dilated, and often grossly so, the actual orifice of the artery at the level of the attachment of the valves may be small, much larger than the pin-hole opening in the valve and not constituting an obstruction but nevertheless smaller than is usual in a patient of like age After successful valvotomy this secondary stenosis at the pulmonary ring may assume a greater importance In Fallot's tetralogy, when a high-grade valvar stenosis is present, the infundibulum is often poorly developed and recessive and so cannot partake fully, 21. Diagram to show how the outflow tract is abnormal in pulmonary valve stenosis cspecially in the presence of a ventricular septal defect, in the hypertrophy and dilatation that normally occurs proximal to such an obstruction. In 'pure' pulmonary valvar stenosis the infundibulum is only slightly affected and its muscle is well developed so that it can hypertrophy with the rest of the yenircle to compensate for the obstruction Commonly, therefore, any subdcvclopment of the infundibular muscle is overshadowed and the only stigma that may remain is thc cndocardial abnormality and a change in form (Fig 21) Thc hypodevelopment of the infundibulum may, however, become important when it is complicated by cxcessive muscular hypertrophy, for in this say at sccondary or associated infundibular stenosis may be added to the valvar stenosis. This is a phenomenon I have been observing for some time and 15 cxcmplified by thc clcctromanometric tracing shown in Figure 22 The upper iracins, 1775 taken at operation and immediately before pulmonary valvotomy, it shows that ·THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 33 the pressure in the pulmonary artery is very low and has little wave form. The pressure in the infundibulum moles to about 80 mm ind in the body of the ventride proper the pressure is about 115 mm. A satisfactory pulmonary valvotomy was done and the lower trang was then 125 1001 50 الريال 3 0 mm Hg PA DNF R. V PRE OPERATION 100% 50+ سميحه mm mm PA INF + R V POST OPERATION 22. To show the effect of pulmonary valvotony on the production or aggruvaton of an infundibular stenosis mmHg - 150 PRE OPERATION 100 mon HC 25 50 0 PA. INF R. V L. V POST-OPERATION 100 mmHg 50 Ллол 23 Another example of change in portion of the gndicat from valve to infum dibular level after pulmonary valvotomy obtained. It will be seen that the effect of the vilvotomy has been to shift the major pressure change from the valve level back to the infundibulum, the nght ventricular pressure is all about 75 mm. Figure 23 shows the same phenomenon in another case. In the top trucing the presence of a dominant valve stenosis us clearly seen, to the lower trang, ·34 THE ANATOMY OF CONGENITAL PULJONARY STEYOSIS taken after valvotomy, there is now a single infundibular stenosis. In both these cases a finger was introduced into the ventricle and the presence of an inſundibular stenosis was confirmed, thc sausfactory relief of the valle stenosis was also noted The infundibular stenosis was then resected The explanation is shown in Figure 24 In 'a' is seen the state of affairs bcforc valvotomy Some degree of infundibular narrowing is present but thc obstructing valve barrier causes such a marked rise in pressure behind it that the walls of the infundibulum are held apart In 'B' valvotomy has been donc successfully and the obstructing valve membrane no longer exists, the infundibulum is, as it were, decompressed, its walls are no longer held apart but can come together and the infundibular stenosis appears Note that though the high pressure in the body of the right ventricle is lowered it is still above normal The previous high pressure + +++ ttt ++ b 24 Diagram to cxplain the mechanism of change in level of gradient in the infundibulum is replaced by a low pressure In other words valvotomy has resulted in a secondary infundibular stenosis appearing When this phenomenon had been recognised I made a scarch through the tracings taken at operation in certain other carlier cases of pulmonary valvotomy and at once other examples were found Figure 25 is from onc of thcsc The upper tracing shows a severe pulmonary valve stenosis, a moderate infundibular stenosis The lower tracing shows a typical infundibular stenosis with no relief of pressure in the right vcntricle. Incvitably this pauent had a poor result Several things can be learned from thesc observations Most, although not all, ucre seen in latc, neglected cases, usually in patients in the twentics or thirues The muscle of the right ventriclc is oftcn cnormously thick and there seems little doubt that this causes, or at Icast aggravates, the condition. In other words the heart is 'musclc-bound' The wall of the scntrcle is so thick that it begins to fill up the ouiflov, tract Thc truly cnormous s1/c is cmphasised by the crista supra. sentriculars which can be felt by the cxploring finger to form a thick uide ridsc ·35 THE ANATOARY OF CONGENITAL PULMONARY STENOSIS BEFORE VALVOTOMY | 100 50 Vilovi 0 PA INFUNDIBULUM R. V AFTER VALVOTOMY 100 50 Wachsanhia 0- PA INFUNDIBULUM R. V 25 A failed use of pulmonary valrotomy in which reference back to the operative trang shows the aggravauon of infimdibular stenosis after valvotomy of muscle perhaps 3 cm ACTOSS so big that it is difficult to punch it with the jaws of the punches usinlly available It may be that after the partial relief of the obstruction by valvotomy the gross hypertrophy of the puscle lessons and the outflow tract opens slightly more; the obstruction is thus further relieved and more muscular regression occurs so that progressive secondary improvement can happen over many months A bennen arde is set up In many, however, the condition seems very resistant and it appears to be almost an end result condidon The possibility of 108 development is a powerful Argument in favour of ady operation in all cases in which the stenosis is at all ugubount. Ang palicy of delay in younger patients must take into account the later development of this secondary muscular obstruction in a heart that has been struggling against a stenoses for many years There an be little doubt that this secondary infundibular stenosis following pulmonary valvotomy is responsible for many of the cases of fuled valvotomy, or of the poor results said to follow the operation. Figure 25 is un cumple of this Kurdhon et al (1953) have also drawn attention, in an excellent article, to this association between releu and infundibular stenosis in certuin cases with intact venticular septuro. In additon to showing clectromanometric triangs illustratung the prettion or development of infundibular stenosis after valvotomy, they abora photographs of three specimens in which the grossly hypertrophied muscle of the authorw tract is clearly seen formung an infimdibular obstruction. They pekee out how thus may be responsible for maintenance of night ventacular obstruction even after a completely adequate palvotomy They also quote . case ba wachalthough a considerable degree of infundibular stenosis persisted after ·36 THE ANATOMY OF CONGENITAL PULMONARY STETOSIS valvotomy, cardiac catheterisation six months later showed a considerable fall in right ventricular pressure had taken place This indeed supports the suggestion that valvotomy may allow diminution of subvalvar muscular hypertrophy and thus progressive relief of the obstructed right ventricle. Blount, Swan et al. (1954) have put forward a strong plea for open transarterial pulmonary valvotomy instead of the 'blind' transventricular operation They point out that their own cxperience and that of some surgcons in the litcrature is that it is not often possible to obtain complete or even adequatc lowcnng of the right ventricular pressure or conversion of the gradient across the pulmonary valve by transventricular valvotomy They assume that this is incvitably due to limitations of the efficiency of the 'blind' procedure and that the valic stenosis is incompletely relieved In certain cases there is no doubt that cien though valvotomy has been performed totally and completely, the development of the secondary muscular infundibular stenosis described above may present satisfactory relief of the obstruction and fall of the right ventricular pressurc. An open valvotomy may give as perfect a valvotomy as it is possible to achicvc, but it cannot correct or avoid this secondary infundibular muscle stenosis This may be corrected by open resection of the infundibular musculature, but it may not be good physiological surgery to do this The great hypertrophy of the musculature of the right ventriclc forms onc of the most prominent features in the external appearance of the hcart It ss usually paler than normal and only few superficial branches of the coronary vessels arc to be seen, in contrast to cases of Fallot's tetralogy in which the muscle is usually darker and more vascular, the coronary vessels being somcumcs large and tortuous and occupying much of the ventricular surface In most cases the right ventricle enlarges over to the left, pushing the lcſi ventricle backwards so that this chamber is often quite concealed in a front vicw'. This means that with the usual left anterior thoracotomy incision the right ventricle is the most prominent structure in the operation field In rare cases (2-3 per 100) there is anuclockwisc rotauon and the right ventricle may be conccaled bencath the sternum In addıuon to enlarging to the left, the right ventriclc enlarges upwards and forwards so that it comes to resemble a poutcr pigeon's chest This has an important effect in that it carries the origin of thc pulmonary artery with it so that the pulmonary trunk comes to lic horizontal or cvcn, in cxtrcmc cases, inchines downwards and backwards, this may also cause scicrc distortion so that the axis of the main pulmonary artery no longer lics in the aws of the infundibulum; ilic Z-shaped junction favours secondary obstrucuon 7 he pulmonary artery The post-stchouc dilatation of thc pulmonary aricry is a prominent and important diagnostic fcature, it is an ov oid enlargement beginning at the level of the pulmonary ring and sccming to affect the whole trunk Actually not all the ·THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 37 arcumference is involved as is seen when it is dissected, for the level of bifurcation is found to be quite low down, indicating that the dilatation us chicfly at the expense of the antenor und night and left lateral surfaces There is no trace of the anus of Valsalve which are smoothed out by the dilatation. In some cases the dilatation extends distally into the left branch (Fig 26). The mode of development of the post-stenotic dilatation 18 still not completely understood for certain, although the observations and conclusions made by Holman (1954) are the most acceptable. He points out the well known physical fact that when a mass of flud is cjected through a narrow construction at high velocity it strikes against the more slowly moving fusd distal to the stenosis and is slowed down, 1t3 kinetic energy is converted into lateral pressure and its stream us deflected laterally or us even completely reversed so that eddies of alternating high and low pressure are set up, these cause repeated impacts over a long time and the clastic wall undergoes structural fatigue and distension. The lateral pres sure effect is further enhanced by the hydraulic prinaple that a widening straum causes decreasing velocity but increases lateral pressure Holman has demon strued convincingly the onset of structural feugue and sudden appearance of aneurysmal dilatation by simple esperiments on lengths of rubber tubing The post-stenotic dilatation of the pulmonary artery provides an important diagnostic radiological feature when occurring in association with lung fields with diminished vasculanty (Fig. 27). The heart is often rather globular except when it becomes grossly enlarged, it then becomes more angular (Fig 28a) ID these extreme cases the dilated pulmonary artery is pushed so fu upwards us to be quite concealed in the heart shadow, but 19 revealed in the anglocardiogram #3 + arcular opacity, for the trimk 15 viewed end on and 3 no longer seen in its long axu (Fig 286). The opecification of the artery may persut throughout the commnation owing to the slow circulation in the resuel Figure 26 show the wul ovoid allatation of the min pulmonary trunk and also to in unaSual degree the manner in which the post-stenotic dilatation may extend into the left pul moniy urtery When the pulmonary artery us camined at operation there is usually no doubt about the diagnosis The form of dilatation of the vessel is characteristic, the wall is felt to be under low teption and may be so thin that the dark blood us asily seen through it. A finger placed lightly on its proximal part nota the low tension and also detects the characteristic thin, jetlike thrill emerging from the valve opeming With slight finger pressure at the base of the artery the tense cone of the valve an be felt in systole and if the finger is passed over it the origin of the emergent jet an be clearly felt Finally if the base of the artery is lightly held between the finger and thumb the whole conelike or domelīkc structure of the stenosed valve an be felt. It is sometimes possible to feel irregular fibrous or even calcified Dodules around the small valve opening These last two manipula tions must be used with great are and for only a very short time, otherwise rapid fall in blood pressure will occur Although the diameter of the pulmonary artery is much larger than normal and is greatest at about its mid-length, the ·26 Radiograph and angiocardiogram to show gross post-stenotic dilatation of the left pulmonary artery ·27 To sbow post-stenotic dilatation of pulmonary trunk.

·sy
a
3
5
b
28 Huge heart in which the shadow of the dilated pulmonary trunk
is concealed in the plain film but revealed in the angiocardiogram

·THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 41 cms 0 2 3 + 29 Perfstant foramen ovale seen in association with pulmonary valve stenosis Artery is often smaller than normal at its ongin and indeed may be very much smaller As already stated, after a successful valvotomy this may cven consaitute * secondary stenons at the pulmonary ning The large hypertrophied right ventricle is matched by the large, dilated dark walled right atrium and its appendage, in contrast to it, in those cases in which the atrial septum is intact, the left emal appendage it seen to be a small, lax pink structure When there is a communication across the septum the left atrial appendage resembles the right appendage in size, colour and tension. This communication is commonly small, often surprisingly so, and is usually a foramen ovale which has become incompetent as a result of the mounting pressure behind the obstructed nght ventride (Fig 29). Much more rarely there is a septal defect away from the fossa ovali ·CHAPTER VII Infundibular stenosis with normal aortic root (syn 'pure' infundibular stenosis, subdivision of the right ventricle) B > OTH Peacock and Keith described examples of pure infundibular stenosis, both the atrial and ventricular septa being closed. Peacock, after describing cases in which the development of the constriction or 'supernumerary septum' occurred before the division of the ventricle was completed, or at an early period of foetal life, then differentiates a type in which the abnormal partition is the only defect He describes a case 'In the cavity of the right ventricle there was a septum, dividing the sinus from the infundibular portion, this septum was perforated by an oval aperture 47 25 mm in circumference, by which the two divisions of the cavity communicated According to Keith and to Peacock a subdivided ventricle may be the only cardiac abnormality, there is no ventricular septal defect and consequently no dextroposition of the aorta It is simply that the normal zone of muscular narrowing which lies between the inflow and the outflow portions of the right ventricle is so over-developed that there is a muscular partition or septum (virtually a much overgrown crista supraventricularis) containing one, two or three openings (Fig 30) The edges of the opening are fibrous, if the lumen is reasonably large (eg I-I 5 cm ) the condition is compatible with long life and it may even be an incidental finding at post-mortem The smaller the stoma the worse the prognosis Keith (1909a) states that the condition is comparatively rare' and found 19 hearts of this nature in the series of 270 malformed hearts which he examined It 42 ·43 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 30 Diagram of pure infimdibular appears, though, that he included a number of cases which should really be dassed as cramples of Fallot's tetralogy with low infundibular stenosis and a large chamber For instance, amongst this 19 were nine with a patent ventricular septum and in four there was also a pulmonary valvar stenosis, in three the ductus arteriosus was persistent and in two the formen ovale was still open. These observations indicate that not all wer samples of 1 imple subdivision of the night ventricle. Maude Abbott (1936) describes two cases of pure infundibular stenoses from amongst her 1,000 total. She writa, 'These ass ure remarkable in that the seat of the stenosis was not at the pulmonary valve but some distance below this at the "ower bulbar orifice" forming & capacious separate chamber with a small orifice in its plece. Pure infimdibular stenosis is not nearly so nire us is thought. Greater expen- Cace in cases of pulmonary stenosis with dosed veatacular septum has led to the recognition and differentiation of a number of examplos Thus I have myself operated upon 9 cases during the last 5 years, since 1948 I have operated on 111 auses of pulmonary valvur stenosis with closed ventricular septum The diagnosis should be thought of when, une case of pulmonary stenosis with closed scpte, no post-stenotic dilatation of the pulmonary artery an be seen although the heart is not too big to conceal it; a buige my be noted at the site of the infundíbulum duc to prominence of the chamber The engrocardbographic appeandce is characteristic u can be seen from Figure 31, which shows the stenosu and the post-tenotic chamber clearly The prominence of the post stenotic chamber which enables it often to be recognised a 1 bulge even on a plain radiograph and which is a direct diagnostic fature et operation, is related to the thinness of the muscle in the outer wall. Thus may thin out so rapidly from just above the stenosis that the greater part of the Outer wall of the chamber may be composed of unle more than thin fibrous tiene ·I_ 31. Angiocardiograms of pure infundibular stenosis ·THE ANATOWY OF CONGENITAL PULMONARY STENOSTS 45 through which the blue blood is clearly seen. This poverty of muscle of course reflects the maldevelopment of the infundibulum as a whole, of which the actual stenosu u but one part. Cardiac antheterisation also enables a firm diagnosis to be made from the characteristic pressure tnang obtained us the catheter is withdrawn from the pulmonary artery and through the infundibular chamber on its way to pass through the stenosis into the high pressure part of the nght peotnde (Fig 32) BEFORE too AFTER 32 Electromanometric trang before and after open resection of pure infundibular stenosis The typical feature is the drop in diastolic pressure within the infundibular chamber as opposed to the pressure within the pulmonary artery An important anatomical feature is that the papillary muscles and tendons of the septal cup of the tricuspid valve arise from the proximal aspect of the contes cular ndge of the stenosis This dose relationship makes it quite umsafe to do a dosed bbad punch resection of the infundibular stenosis, for organic tricuspid incompetence may be caused this I have anused in one case Since then I have performed open resection of the stenosis under direct vision when it has been cany to demonstrate the precision that is needed to avoid damaging the tncuspid valve mechanism This dose relation of the tricuspid valve to the stenosa mens that when catheter withdrawal pressure trading is being made the atheter may pass directly from the low pressure of the infundibular chamber into the night atrium, only if

·46
THE ANATOMY OF CONGENITAL PULMONARY STENOSIS
the catheter is then advanced again may the body of the right ventricle be entered
and a high-pressure chamber demonstrated
Figure 33 shows the total resection of infundibular stenosis that has been
possible under direct vision surgery. In Figure 32 can be seen pressure tracings
made before and after operation, the obliteration of the pressure gradient shows
that the obstruction has been completely relieved
ст
33 Tissue removed at open resection of infundibular stenosis

·CHAPTER VIII Pulmonary atresta, tricuspid atresia Pulmonary atresia Nacellent survey of this condition has been given by Allenby, Brinton, Campbell and Gurdaer (1950) A Arterial attesta The pulmonary artery may be obliterated for a verying distance either just above the valves (Fig 341) or throughout its length There may be po trace of the pulmonary stem or a fine fibrous thread may lead up to the horizontally nmomg retsel formed by the right and left pulmonary arteries Lo these coas the circulation of blood within thc pulmonary arterias is almost stagnant and 13 wholly dependent upon collateral arculation from the bronchial artery system, unless the ductu bus perusted Sometimes the right or the left or even both pulmonary urteniss may be obliterated In cases of pulmonary atresia the surgcon must often Iplore the local Anatomial arringement in the hope of finding a pulmonary vessel large enough to use for a useful anestomosis to 1 systemic irtery 47 ·48 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 5 с 34 Three examples of small pulmonary trunk and atresic valve (After Allanby, Brinton, Campbell and Gardner) (a) The atresic valve consists of a mass of fibrous tissue in which no cusps can be made out (6) The small size of the infundibulum and valve ring can be seen with the tiny pulmonary trunk, which widens just below its bifurcation (c) Atresic valve seen from above, note the orifice is eccentric Valvar atresia This is a fairly common and important form of pulmonary atresia that is well described by Allanby et al (1950) The atresic valve can be recognised as consisting of two very imperfectly formed cusps fused together, often the atresic valve is eccentric, the cusps being fused obliquely to the arterial wall (Fig 34a) The fibrous obliteration may, 10 rare instances, be just below the valve cusps, which themselves are normal and well formed (Fig 35) Some degree of infundibular maldevelopment is also usually present, which is not surprising considering that the pulmonary channel is functionless Occasion- ·49 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 35 Photograph of temple of pulmonary atresia which occurred immediately below the semilunar valves which are well formed life was maintained by a anall persistent ductus ally the night ventnde is well formed in the case depicted in Figure 35 there was tricuspid stenosis and i small thick walled infimdībulum but no ventricular septal defect, the drculation in the pulmonary artery being maintained through a persutent ductus In most cases the ventricular septum 18 defective The embryological fact of the fixion of the distal part of the bulbus cordis into the truncus arteriosi, and the anatomical description of the arterial 100ť which is formed by this distal portion (see p 21) supply the explanation of these forms of pulmonary atresia which must be due to imperfect development or to obliteration of the most distal part of the bulbus cordis Tricuspid atresia This type is really a group of vuying degrees of imperfect development or atresia of the right ventriclc and aspecually its inflow portion. It, in fact, Ulustrates admirably the twofold construction of the right ventacle, for in some cases there 13 almost complete suppression of the inflow portion yet the infundibulam may be almost normal. In 10 severer form there may be no night ventride at all. Characteristically the tricuspid orifice is greatly stenosed or obhterated und ·50 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 36 Diagram of tricuspid atresia in which the outflow tract of the right ventricle is almost normal Septol defect the sinus or inflow portion of the ventricle does not exist or is vesugial The infundibulum may be present and moderately well developed with a small ostium connecting it to the atrophic body of the ventricle If the tricuspid orifice is completely obliterated the only route for the blood is through a persistent foramen ovale or septal defect and thence into the poorly developed right ventricle through a ventricular septal defect As the right ventricle is either non-functioning or poorly functioning it is rare to find the infundibulum completely normal and it may exist as a small thick-walled chamber Often there is a severe high infundibular stenosis or even complete pulmonary atresia, the infundibular cavity may then contain only clot If pulmonary atresia is present the ductus arteriosus is usually persistent (Fig 35) The specimen depicted diagrammatically in Figure 36 shows a well-developed infundibulum with a good-sized pulmonary artery and normal valve cusps The sinus is completely obliterated and the infundibulum opens by a small stoma into the left ventricle A large atrial septal defect is shown ·CHAPTER LX Fallot's tetralogy T His is the most important condition to be described for it consututes some 75 per cent of all cases of congenital cyanotic heart disease and forms the biggest group of cases of congenital pulmonary stenosis The term Tetralogy emphasises that the stenosis 18 associated with a ventricular septal defect, in over nding dextroposed aorta and a fourth element-hypertrophy of the night ventricle. This last seerns a faulty presentation for the muscular hypertrophy is not a primary maldevelopment but a physiological change secondary to the pulmonary stenosis and probably also to the nght to-left shunt It is rather specious to include it as a fourth developmental abnormality In fact, the more one studies these cases clinically and pathologically the less msfactory docs the general term 'Fallot s tetralogy' appear to be since it en courages the acceptance of a whole group of cases which, although having a number of dinical features in common, ure often dissimilar anatomically In this connection it is necessary to emphasise once more the importance of Steful observation of the heart at operation, 1.c in the living, functioning state, and of not being muled by what is seen at post mortem when the heart is inert, rigid, contracted and often hardened by fixation. It is commonly stated that the obstruction in Fallot's tetralogy is muscular' or tubular', the implication being that it extends over a considerable distance. I have not been able to satisfy myself that the obstruction is of this mature, it is usually angular or diaphragmatic and it would kell that most people repeaing these statements have ather pot SI ·52 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS examined specimens themselves or have looked at contracted specimens and have misread what they have seen It is especially easy in a fixed, contracted specimen to suppose that the obstruction is muscular because the walls of the infundibulum may be closely approximated, whereas in life an adequate, albeit diminished, lumen is present In a proportion of cases a localised hypertrophy of muscle forms the basis or foundation of the chief obstruction which is essentially fibrous It is not possible to accept the observations and conclusions of Donzelot, d'Allaines et al (1952) and Soulié et al (1952), most of the specimens used for their examinations seem to have been old, rigid post-mortem ones Figure 37 compares the anatomical arrangement of the normal right ventricle 2 4 in pour -6 b 37 Diagram of the normal right ventricle (a) and of the right ventricle in Fallot's tetralogy (b), in which are indicated the various levels at which stenosis may Occur I Pulmonary atresia 2 Valvar stenosis 3 High 4 Intermediate infundibular stenosis 5 Low 6 Subdivision of the right ventricle (a) with that seen in Fallot's tetralogy (6) It will be seen that there is partial suppression of the outflow tract or infundibulum In contrast, the inflow tract is larger and hypertrophied, a septal defect lies in the inflow chamber immediately behind the crista supraventricularis Although the outflow channel is small, it is nevertheless adequate to carry a sufficient blood-flow to the lungs cxccpt for an added stenosis that may occur at one or at two levels The highest level of obstrucuon, indicated as (1) in Figure 37, is pulmonary atresia, (2) indicates valvar stenosis and 3, 4, 5 and 6 indicate various levels of infundibular stenosis A valvar and an infundibular stenosis may co-exist Figure 38 is a photograph of an actual specimen of Fallot's tetralogy which demonstrates thesc features The rather diminutive crista supraventricularis can be seen separating the small infundibulum or outflow tract from the large thick- ·53 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 7 INFLOW OUTFLOW CRIST 38 Photograph of specimen in Fellot's tetralogy there is a valve stenosis walled inflow chamber, in the antenor and upper part of which lies the septal defect. Although the outflow tract is so much under-developed, so much smaller its lumen u in fact adequate ccept at one level that is at the valve where there 13 a severe stenosis Figure 39 shows another crumple in which the sume features an be seen acept that there u a combined velvar and infundibular stenosis In Figure 40 can be seen the formation of the infundibular canal in yet a further case of valpar stenosis occuring in Fallot's tetralogy here again although smaller than normal, the lumen of the infundibulum is quite adequate, the true obstruction bemg at the pin hole yalyc onfice seen in the distance. The form of the cristi rupraventriculars is aspecually important in this specimen as it indicates the mode of formation of thus structure from fusion of the nght and left septul bands, a and b (Fig 11, p 14), the septal defect u also well displayed. This basic amatomy and the expanded details now to be described form the bedrock on which must be founded any operative treatment for the relief of the stenous or for total correction of the deformty ·54 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS -Valvar stenosis Cristo supraventricularis Infundibular stenosis 1 39 Photograph of specimen in Fallot's tetralogy, there is a combined valvar and infundibular stenosis Valvar stenosis It is surprising that a few years ago there was great opposition to acceptance of the teaching that pulmonary valvar stenosis occurs with moderate frequency in Fallot's tetralogy It would, in fact, be surprising if it did not occur when we recall that the anomaly is dependent upon malformation of the bulbus cordis, from which the valves also are developed Actually, the literature contains a number of descriptions of valvar stenosis in Fallot's tetralogy Thus Keith (1909a) in a report on 270 cascs found that a valvar stenosis was present in 25 out of 63 cases (40 per cent) of what can be described as examples of Fallot's tetralogy. Brown (1939) states, 'In cases where there is an arrest of the developmental expansion of the infundibulum, the infundibulum is foreshortened and may exist as a small fusiform cavity with thickened walls In about half of the cases there is also fusion of the pulmonary cusps' Sellors and Belcher (1950) mention that out of 65 cases examined at operation 20 were thought to have a valvar stenosis and 45 an infundibular one They do not, however, give their criteria ·55 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS PIN-HOLE VALVE INFUNDIBULAR CANAL SEPTAL DEFECT 40 Photognuph of specimen in Fallot's tetralogy in which can be seen thraphe of fuson of the right and left septal bands (a und b) to form the crista nupraventriculado for dugnosis por do they state of pressure observations were made. In Abbott's series (1936) it is difficult to be sure of the exact incidence from the tablas given My own operation ctperience covers 168 cases of Fallor's tetralogy in which a direct operation was performed on the pulmonary stenosis and a careful diagnosis of the type and ate was made according to criteria laid down clsewhere (84) The distribution of the types was Number Percentage Valvar stenosis 59 35 Infundibulat stenOSIS 72 43 Combined valvar end infundibular stenosis 37 Total 168 The condition of the valvar stenosis yung and reflects the degree of hypodevelopment present. Thus at one extreme we see those cases of valvar atrosu (Fig 34) ot near valvur atreun in which there is a pin hole-size opening with no tnce of independent cusp formation. At the other extreme the commissures of the fused tople cusps an be detected in the hemisphenal duphngmatic or dowelike projection which is formed by the büllowing out action of the ·56 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 41 Diagram to show post-stenotic dilatation of the pulmonary trunk in Fallot's tetralogy This IS uncommon $ ventricular pressure (Fig 38) The fused cusps may be conical or ripple-like (Fig 39), in these examples the commissures may not be symmetrical. In the more severe forms the pulmonary valve is often bicuspid instead of tricuspid and the two cusps are fused along their margins, giving a small oval or round opening This type is more common with the more severe forms of infundibular hypoplasia Where the valve is tricuspid and is better developed the stem of the pulmonary artery may show a fusiform post-stenotic dilatation with obliteration of the sinuses of Valsalva (Fig 41), although it is extremely rare to see the artery at all large and certainly almost never as big as occurs in pulmonary valve stenosis with a closed ventricular septum The commonest type, in fact, indicates marked developmental arrest, and is of considerable interest and of great practical importance because it is casily overlooked on inspection at operation In this the fused valves form a globular or almost spherical membrane with a small central aperture (Fig 42) This globular valve distends the first part of the pulmonary artery which conforms to its shape, immediately above it there is a waistlike 'constriction of the artery which really indicates its true small size, beyond this again is seen a post-stenotic dilatation. The whole artery is diminutive On first examination the appearances suggest the sinuses of Valsalva are present Careful inspection reveals the swelling is uniform and not thlobular, as are the sinuses, and it may then be confused with thc dilatation due to a high infundibular stenosis. The spherelike structure can, however, be seen and felt to become tense in systole and lax in diastole which is diagnostic of a valvar obstruction The palpating finger can also feel the tiny cmergent et on the summit of the dome The artery beyond the valve is lax in systolc, the low tension contrasting sharply with the high tension of the valve sphere Thc artery is almost emptied of blood in diastole, as the tense valve relaxes the small amount of blood it contains is quite enough, as it is sucked back into the ventricic, 10 empty almost completely the poorly-filled small distal artery.

·57 THE ANATOMY OF CONGENTTAL PULMONARY STENOSIS cms 1 2 3 4 42 Globuler valve stenou typical of Fallot's tetralowy The small size of the pulmonary artery in valvar stenosis, and especially the construction just detal to the valve, make the present technique of closed val votomy by valvotome and pandmg dilator often rather ineffective; the dating Instrument my fit the lumen and it may therefore not be possible to obtain muffiaent dilatation to spht the valve widely An open technique is really needed when the artary is so small It should be emphasised that the pulmonary outflow tract, including the pulmonary artery, is commonly much smaller in cases of vulyar stenosis than in infundibular stcposts It seems as if valyu stenosis is associated with a greater retardation of development of the bulbus in its extreme form it 13 secos valvar atroia When the vulvar stenotu is combined with an infundibular stenosis the fact may be recognised in most cases by anternal inspection and palpation of the out flow tract aposed at operacion. Thus, light palpation of the valve conc will give an idea whether the full ventricular pressure as transmitted to it or whether the tension is only shghtly higher than in the lux pulmonary artery, mdicating that a more proximal mfundibular stenosis is reducing the ventricular pressure before it can reach the valve cone. Deformation of the surface of the infundibulum, as will be described later will support the supposition of an associated infundibular stenosn. The diagnosis an be completed for certain by electromenometric pres fure readings which will not only identify the presence of two changes in pressure -two stenoses--but will also indicate the relative importance of the two, ·58 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS PA INFUNDIBULAR CHAMBER R V 100 mmHg 50 marathon Shah with title 0 43 Electromanometric tracing of combined valvar and infundibular stenosis whether the valvar or the infundibular stenosis is the more important or whether they play an equal part. Figure 43 shows a combined valvar and infundibular stenosis before valvotomy and infundibular resection It is remarkable how the presence of a true and predominant valvar obstrucuon can be overlooked or ignored in examination of a specimen post-mortcm. Once an abnormality of the infundibulum is observed this is often taken to be the significant obstruction and no further proper search is made. In the fixed contracted state of the dead heart this might be excusable but even then a valve with an effective opening of 2-3 mm must be significantly stenosed. Examination of the living heart at operation reveals the true state of affairs with much greater accuracy if the changes mentioned above are sought and if clectromanometric pressure recordings are made The radiological diagnosis of valvar stenosis in Fallot's tetralogy and its differentiation from infundibular stenosis will be dealt with in a collective description later in this chapter Infundibular stenosis The basic problem in the infundibular stenosis in Fallot's tetralogy is, as already explained, an arrested expansion or development of the infundibulum so that it is smaller than normal Although in all cases the infundibulum is small, and sometimes extremely so, the functional lumen is adequate, apart from the stenosis, except in the group in which hypoplasia is extreme. Although various 'types' of infundibular stenosis are depicted in Figure 44 and are to be described separately, it should be appreciated that fundamentally they all follow the same pattern; they are dissimilar only as a result of the level of the fibrous constriction which forms the real obstruction within the partly suppressed infundibulum Thus, in its simplest form, the obstruction is at the junction between the sinus and infundibulum (Figs 30 and 37), the usual moderate demarcation between the two parts of the ventricle is represented by a contracted muscular septum with an ostium surrounded by fibrous tissuc so as to form a small rigid opening between the two parts of the ventriclc and acting as an obstruction In the other types the truc obstruction lies within the infundibulum at onc of the arbitrary levels depicted in Figure 37,10 it may be low, intcrmcdiatc or high.

·59 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS It may be only a slight annular thickening or it may be a firm raised linear fibrosis, sufficient to form a diaphragmatic type of obstruction. Providing the obstruction is not too near the pulmonary valve there will always be a post stepotic infundibular chamber varying in size with the distance of the obstractron below the valve and with the thmness of the outer wall The formation of this infundibular chamber is due to the same process of post-stenoac dilatation' described m connection with pulmonary valvar stenosis. When the mfundibular stenosis is high the beginning of the pulmonary artery is affected by the post stenotic dilatation (F1g 44B) Whatever the level of the obstruction there 18 always a ground-glassing of the endocardium of the infundibulum uc the endocardrum is thicker lod whiter than normal and, according to Kath (1909), this is becmise the endocardial tissuc fibrocellular in texture; it 15 embryonic rather than inflammatory in its microscopic structure. It is now included under the term endocardial fibroclastotis As the years pass, this endocardial thickening becomas denser and more opaque so that it may form a thick layer The greatest increase in fibrous thicken ng occurs at the BarTowest part of the lumen, whether it be a duphragmatic or annular murowing in the infundibulum or at the valve itself; the daily wear and tear over the years auses increasing fibrosis amounting to a dense, hard, often cartilage-like scar and ultmately, calafication. Calafication is commonest in the valve but is also seen in infundibular stenosis The dense endocardial fibrosis may extend over the crista supraventaculatus The effect of the angular band or diaphragmatic like stenosis with its endoardial thickening is to tether the outer or anterior wall of the infundibulum to the anterior surface of the crista supraventricularis which here forms the postenor wall of the infundibulum, thus it does because the thickened endocardium parses from the crisur to the antenor wall of the infundibulum rather like a loop or a Sturup This tethering effect can actually be observed in many cases on the outer surface of the infundibulum where the level of the stenosis may be demarcated by a furrow or groove which is deeper and more definite in systole. In the infant and child thus is relatively supple but it becomes tougher and more rigid as the years pass and so 10 tethering 20100 increases in this way it holds beck the wall of the infundibulum from growing properly, in other words it continuously aggruvates the relative backward development of the infundibular canal which annot keep pace with the growth of the mdividual and of the heart as a whole, Thus tn infundibular stenosis becomes relatively more sevete as the patient geta older, and it also becomes absolutely more severe &3 e result of progressive fibrosis of the stenosed ostium, contracture of this fibrous tissue and silting up of the orifice by depoudon of platelets and their organisation and the formation of warty nodulas or vegetations This process of steadily increasing stenosis is uportant in considering treatmerit, for it should be clar that the adier treatment is carried out the better, beause, with the relief of the stenosis, the infundibular apel, indeed the whole of the pulmonary channel, can then grow with the patient If operation is delayed

·A
B
2
C
시
D
44 Diagram of types of infundibular stenosis. A Hypoplasia B High stenosis
C Intermediate D. Low

·61 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS until growth has ceased there is a limit to what can be achieved in satisfactory relief of in infundibular obstruction. This of course only applies to operations involving direct relief of the stenosis itself, the indirect or anastomouc operations do nothing to encourage the growth and development of the infundibulum, in fact by short-arcuiting it they favour its adding up The maldevelopment of the infundibulum inevitably affects 163 muscular construction the crista supraventricularis is always smaller and less developed than normal (Fig 38) and is sometimes very small in the more severe forms Figure 40 shows how the primary formation of the ciste by fusion of the nght und left bulbar ndges (14) may remain evident, pointing to perual arrest of development. In the same way the night and left antensions of the cut down the lateral and septal walls to the apa are smaller and less well developed The imperfect development of the musculature is often also seen in the outer or anterior wall of the infundibulum distal to the stenosis Inevitably this part of the muscle of the right ventricle will not thicken as does the mude prormal to the stenosis, but it may still form a substantial layer More often, however it 13 thin and may contain murde only just above the stenosis, and this rapidly diminishes until the greater part of the outer wall is devoid of muscle and presents # & thin walled bulge on the surface of the ventricle through which the dark blood is plainly seen. This thmomg of the outer wall of the infundibulum in association with the process of post-stenotic dilatation, can result in quite a large and prominent infundibular chamber belng formed when the stenosis is low The projection of this chamber on the surface is a notable diagnostic feature both radiologically and at operation Although it is emphasised that the truc obstruction in mfundibular stenosis lies dominantly at one level, even though there is some arrest of the development of the infundibulum as a whole, there o no doubt that the effect of this stenosis aggravated by the systolic contraction of the infundibulum. In fact it u probable that the aifiacacy of emptying is, as it were, cut short before the haght of systole us the walls of the narrowed infundibulum come together This has been demonstrated by Hilano Lind and Wegelius (1954) using a rapid brplane angio aardlograph technique. Rodbard and Sheffer (1955) have demonstrated the same by ardiac arthcternation (see p 102) These matters will be discussed more fully later when the control mechanisms of the night ventride arc being considered Having presented these general observations on infundibular stendars we may now proceed to the individual types (Fig 44). Hypoplana of the mfundibulum This type (Figs 444 and 45) is due to almost complete arrest in the development and capansion of the infundibulum so that it is only 2 DAITOX muscular channd, too small to carry an adequate blood flow to the lungs, even so it is still ·62 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS Ia cms 2 3 4 45 Hypoplasia of infundibulum further narrowed at one level by a secondary fibrous stenosis or by valvar stenosis, as always occurs in Fallot's tetralogy The pulmonary artery is small and poorly developed The condition in its severest forms is only little removed from pulmonary atresia and is inevitably most often seen in infants and young children Inevitably, because in them any degree of hypoplasia of the infundibulum must be more severe because of the small size of their outflow tract and also because early death is common and fewer live to be seen at an older age The narrow channel surrounded by muscle is likely to be grossly contracted by rigor mortis, and even more so if fixed in formalın, so that the appcarance of a purely muscular obstruction is aggravated It 15, in a sense, true that the obstruction in this type is ‘muscular' in that the whole infundibular canal is inadequate If the child lives a few years thc infundibulum will grow sufficiently with the rest of the heart to lessen, to a certain cxtent, the extreme smallness of the lumen seen in the infant and it is then casier to appreciate the part played by the localısed fibrous constriction in complcung the obstruction of the poorly developed outflow tract (Fig 45) ·63 TIL ANATOMY OF CONGENITAL POLMONARY STENOSIS (1) Husk onfundibular stenesis lo this type (Fig. 44B) the degree of arrest of development is not so extremo o in type A, the infundibule part of the ventnde is larger and the pulmonary urtary u better developed although often still too small. The obstruction is a firm anular or diaphragmatic thickening of the cadocardium just below the valve level. The condition is admirably portrayed by Peacock (Fig 46) ind is also shown in Figures 47 and 48 In alder patients widespread secondary fibrosis occurs at the obstruction, and may extend proamally over the walls of the imperfectly developed infundibulum to form a thick layer of lang (endocardial 46 High infundibuler stenosis a portrayed by Peacock fibroclastosis) over the surface of the crista supraventnculans Figure 47 also shows considerable fibroelastosta. As the stenotic ring is very near the valves there is no space for a true chamber to form from stenotic diatation, but the effect of this process causes the vulve ring and the first part of the utery to dilate in a spheacal mapaer, thus mimicking the post-stenouc dilatation seen in milyar stenosis The appearance of the artery u rather like that of a drum-stus, detal to the globular formation the walls of the yeste are parella and the tension of both the dilatation and the trunk is the Ame and is low, this b to contrast to valvur stenoses in which the prosomal dilatation is tense, cod immediately beyond it is a constriction before the more distal dilatetion. The post-stepouc dilatrtion of the pulmonary artery may extend to 10 muin branches, especially the left one, ·3 47 High infundibular stenosis ·65 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS Pulmonary artery Valve CUSPS 48 High infundibular stenotu (ui) Intermediate murdibular stenoss In this type (Figs. 440 and 49) the actual fibrous obstruction is ututed from I am to 2 5 cm. below the valve level so that a definite post-stenotic infundibular chamber forms Thus chember lined by thickened wodocardium iod u boted proumally by a fibrous obstruction ether annular or diaphragmatic (Fig 49) The amount of fibrous tissue in the obstructing ning or diaphragm varies as e general pnnapic the younger the patient the less fibrosis there is, in older patient a dense, fibrous, nigrd, often verrucose margm surrounds the narrowed entry into the chamber The outer wall of the chamber may be thin nod fibrous, or pertly or wholly muscular although always much thipa than the wall of the ventride pronnal to the obstruction. When the wall is deficient in muscle a ·66 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS AORTA D PULMONARY ARTERY AINFUNDIBULAR CHAMBER INFUNDIBULAR OSTIUM OUTER -WALL OF AV. 49 Intermediate infundibular stenosis globular swelling, dark blue from the contained blood, projects from the surface of the right ventricle below the pulmonary valve. This can be observed on plain radiography and can be further demonstrated by angiocardiograms (Figs 50, 55, 56 and 57) Figure 51 shows the stenotic ring removed by infundibular punch resection (10) Low infundibular stenosis This type (Fig 44D) and type 'c,' the intermediate, are really only variants, being arbitrarily divided by the level of the fibrous obstruction below the valves, and thus in the size of the infundibular chamber which varies between 25 cm and 5 cm in length If the outer wall of the chamber is uniformly muscular it will not project markedly, but if the wall is thin and the muscle extends into it for only 1-2 cm. the chamber is large and prominent and can be demonstrated radiologically as well as at operation (Fig 31, P 44) Muscle forms the basis of the obstructing ring, but the margins of the ostium arc always fibrous Sometimes two or even three openings may be present. The specimen shown in Figure 52 is an examplc of an unusually large infundibular chamber in association with a low stenosis In fact, from the si/c of this chamber it resembles closcly the type seen in purc infundibular stenosis described carlier It has a large muscular scptum situated at thc junction of the sinus and infundibulum and perforated by an ostium with fibrous margins, lls outer wall thins out so that it is almost completcly dcficient in the upper part, indicaung the development of the infundibulum was definitely dcfccuvc.

·Chamb
-Stenosis!
-
50 Angiocardiogram of Intermediate infundibuler stedonia
cm
cm
St Photograpb of specimen obtuned by punch resection from patient in Fig so
F

·68 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS Pulmonary artery Septal defect Cms -- 2 14 52 Low infundibular stenosis, notc the large scptal dcfcct and the largc infundibular chamber with a thin outcr wall However, there is also a large ventricular scptal defect mcasuring somc 4 cm in diameter, so large as to throw the two ventricles virtually into one An important practical feature in infundibular stenosis is the obliquity of the scptum between the infundibular chamber and the main body of the ventricle This obliquity is slight or absent in a high stenosis, but becomes quite marked in low stenosis, in fact in its lower part this scptum lics ncarly parallel to the outer wall of the ventricle with only a narrow space intervening Thc stonoscd opening between the two compartments is higher up on thc partition in such a way as to make surgical access difficult Figure 53 illustrates the problem diagrammatic- ·69 THE ANATOMY OF CONGENITAL PULMONARY 51 ENLISIS 53 Diagrum to show how the obliquity of the secondary septum in low Infundibular Henodi may make punch rcrcction from below un favourable. ally in the woal techmque of punch resection of the infundibular stenosis the punch is inserted through the ventricular wall below the obstruction, it will be seen at what a disadvantage it may lie. If it is introduced from above, it approaches the stenosis and the partition much more favourably Thus techmique can only be used if the infundibular chamber is large Combined valvar and infundibular stenosis Since the deformity in Fallot's tetralogy is due to maldevelopment of the bulbus cordis which extends distelly to include the pulmonary valves us well as forming the infundibulum, it follows that malformation of the valves is to be cxpected in combination with infundibular stenosis as well as an independent condition In the table on page 55 which gives un analysis of 168 cases treated by direct operation, combined pilvar and infundibular stenosis was present in 37 (22 per cent) The valvar stenosis has already been fully described the infidibular stenosu us tuually of high intermediate type. I conot recall seeing a lot infundibular Acosts combined with a valmir stenosis, doubtless this is because a really low infundibular stenos represents a les severe malformation whereus combined yalvar and infundibilar stenosis 11 ordioanly & more severe malformation The presence of two stenoses may be recognised befort operidon by angiocardiography or by cardiac antheteaution, or by both. At operation the combined features of the two lesions are to be recognised. The final diagnosis coma from electromopometric pressure recordings made with atheter and needle punctures in this way, in addigon to confirming the presence of the double lesion, the level of the infundibular stenosis and the relapve importance of the two stenoses con be assessed (Fig 43 P 58) ·70 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS The septal defect The defect in the septum is situated immediately behind the crista supraventricularis and its lower margin and anterior and posterior boundaries are rounded and muscular (Fig 38), its upper margin is the aortic ring although it has no real upper margin as it opens directly into the aorta The defect is usually smallest when the infundibulum is well formed, this rule is not invariable for in the specimen shown in Figure 52 in which the obstruction is very low, there is a huge ventricular septal defect 4 cm wide The anatomy of the septal defect has become of greater importance now that direct operation for its closure is possible Although it appears, especially in the dead heart, to be a rigid round or oval defect, its upper margin can be very easily approximated to the aortic margin before fixation, and even the fact of the overriding aorta does not prevent this In the extreme forms of dextroposition the pulmonary artery is usually considerably hypoplastic, and closure of the septal defect would then be unwise because the poor pulmonary channel would not be able to carry the extra circulation effectively for the heart to readjust itself to such profound alteration of its mechanics Although there is usually no true upper margin to the defect, the actual aortic ring provides strong and suitable material for suturing It is also worth remembering that the right atrium is a direct anterior relation of the aorta adjacent to the defect and sutures could in fact be passed through this to help to close the upper septal margin An important posterior relation of the defect is the septal cusp of the tricuspid valve with its tendons and papillary muscle In Fallot's tetralogy the septal defect is very close to the cusp and may extend under it, but rarely to the same degree as may occur in isolated ventricular septal defect in which the septal cusp may cover quite an appreciable amount of the defect. Figure 54 shows a specimen of Fallot's tetralogy in which the defect is covered by the tricuspid valve When the defect is small its posterior margin reaches no further back than the atrioventricular rings, and sutures inserted for closure can pass directly from the muscular wall of the defect to the aortic root When the defect is larger it extends further backwards and in so doing comes to lie more and more under the atrioventricular rings, 1 e. it extends beneath the mitral and tricuspid valves which form part of the roof, the septal cusp of the tricuspid covering its right aspect In such cases it would be wrong to attempt to close the posterior part of the defect by suturing to the aortic ring, this part must be closed by picking up with the sutures the part of the atrioventricular ring which gives common origin to the iricuspid valve on one side and the mitral valve on the other After the posterior part has been closed in this way, the more anterior part can be closed by sutures which the aortic root Another structure with an important rclauonship to the scptal dcfect is the atrioventricular bundle The night branch has alrcady been mentioned as demarcaung the juncuon between the sinus and infundibulum of the right ventnclc. The main bundle bifurcates immediately behind the posterior limit of pick up ·71 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS Tricuspid valve overlying septal defect Cms 54 Heart in Fallot a tetralogy to abow that the ventricular sepaal defect may be covered by the septal cup of the tricuspid palve the defect and the right branch runs down the septum e frection of a centimetre in front of the posterior margin, it is well behind the criste supraventriculars The degree of dextroposition of the sorta of over riding venes from case to case, but is again usually dependent on the degree of urest in development of the infundibulum. In the severe forins with a high stenosis and a large septal defect the north seems to over side at least 50 per cent In addition in these severe cases the escending aorta is usually very dilated, a fact observed and commented upon by Pacock In Chapter VI ( 87) the significance of dotroposition is more fully doscussed, and aspecially the view of Lillehel et al (1955) who have indicated that its apparent rather than real ·70 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS The septal defect The defect in the septum is situated immediately behind the crista supraventricularis and its lower margin and anterior and posterior boundaries are rounded and muscular (Fig 38), its upper margin is the aortic ring although it has no real upper margin as it opens directly into the aorta The defect is usually smallest when the infundibulum is well formed, this rulc is not invariable for in the specimen shown in Figure 52 in which the obstruction is very low, there is a huge ventricular septal defect 4 cm wide The anatomy of the septal defect has become of greater importance now that direct operation for its closure is possible Although it appears, especially in the dead heart, to be a rigid round or oval defect, its upper margin can be very casily approximated to the aortic margin before fixation, and even the fact of the overriding aorta does not prevent this In the extreme forms of dextroposition the pulmonary artery is usually considerably hypoplastic, and closure of the septal defect would then be unwise because the poor pulmonary channel would not be able to carry the extra circulation effectively for the heart to readjust itself to such profound alteration of its mechanics Although there is usually no true upper margin to the defect, the actual aortic ring provides strong and suitable material for suturing It is also worth remembering that the right atrium is a direct anterior relation of the aorta adjacent to the defect and sutures could in fact bc passed through this to help to close the upper septal margin An important posterior relation of the defect is the septal cusp of the tricuspid valve with its tendons and papillary muscle. In Fallot's tetralogy the scptal defect is very close to the cusp and may extend under it, but rarely to the same degrec as may occur in isolated ventricular septal defect in which the septal cusp may cover quite an appreciable amount of the defect Figure 54 shows a specimen of Fallot's tetralogy in which the defect is covered by the tricuspid valve When the defect is small its posterior margin reaches no further back than the atrioventricular rings, and sutures inserted for closure can pass directly from the muscular wall of the defect to the aortic root When the defect is larger it cxtends further backwards and in so doing comes to lie more and more under the atrioventricular rings, i e. it extends beneath the mitral and tricuspid valves which form part of the roof, the septal cusp of the tricuspid covering its right aspect In such cases it would be wrong to attempt to close the posterior part of the defect by suturing to the aortic ring, this part must be closed by picking up with the sutures the part of the atrioventricular ring which gives common origin to the tricuspid has valve on one side and the mitral valve on the other After the posterior part been closed in this way, the more anterior part can be closed by sutures which pick up the aortic root Another structure with an important relationship to the septal defect is the atrioventricular bundle The right branch has already been mentioned as demarcating the juncuon between the sinus and infundibulum of the right scntrcle. The main bundle bifurcates immediately behind the posterior limit of ·THE ANATOLIY OF CONGENITAL PULMONARY STENOSTS Tricuspid valve overlying septal defect cms 54. Hart In Fallot e tetralogy to show that the ventricular sepul defect may be covered by the sepul cup of the tricuspid salve. the defect and the right brunch runs down the septum a fraction of a centimetre in front of the posterior margin, it is well behind the crusta supraventricularis The degree of destroposition of the porta or over ndmg varies from case to case, but is agun urally dependent on the degree of rest in developident of the infundibulum. In the severe forms with a high stenosis and a large septal defect the norta seems to orer ade at least 50 per cent In addition, in these severe auses the ascending Sort is usually very dilated a fact observed and commcated upon by Peacock. Io Chapter XI (p 87) the significance of dextroposition is more fully discussed, and aspecially the vic77 of Lilleha et al (1955) who have indicated that it is apparent rather than real.

·IV Lhas already been said The subject is, however, so important that it is CHAPTER X The recognition and differential diagnosis of the type and level of the obstruction in Fallot's tetralogy ANY of the details of the recognition of the type and level of the various forms of pulmonary obstruction emerge from a consideration of what desirable to correlate the various features and to enlarge upon them by a more detailed consideration of some of the radiological and other aspects One of the easiest pre-operative radiological diagnoses can bc made in the casc of a large infundibular chamber associated with a low stenosis. Figure 55 shows clcarly how the chamber stands out from the left margin of the heart shadow in the routine postero-anterior view, in the past this shadow has often becn looscly described as being due to a 'prominent conus region', it is characteristic of an infundibular chamber and it is brought into cven greater prominence in an obliquc view (Fig 556), angiocardiograms again demonstrate its prescncc conclusively (Fig 550) Figure 56 shows another cxample of a large infundibular chamber In both these cases the diagnosis was confirmed at operation and the intervening fibromuscular diaphragm was punched away so as to relieve the stenosis, confirming that the obstruction was diaphragmatic and not long and tubular. That confusion and misunderstanding cust about what is really a simple state of affairs is shown by Figure 57 As will be seen from the plain radiograph on the bisa left, 'a', a characteristic bulgc duc to an infundibular chamber is present, 72

·0
C
55 To show the bulge on the bart contour formed by an infundibular chamber

·I has already been said. The subject is, however, so important that it is CHAPTER X The recognition and differential diagnosis of the type and level of the obstruction in Fallot's tetralogy ANY of the details of the recognition of the type and level of the various forms of pulmonary obstruction cmerge from a consideration of what desirablc to correlate the various features and to enlarge upon them by a more detailed consideration of some of the radiological and other aspects One of the easiest pre-operative radiological diagnoses can be made in the case of a large infundibular chamber associated with a low stenosis. Figure 55 shows clcarly how the chamber stands out from the left margin of the heart shadow in thc routinc postero-anterior vicw, in the past this shadow has often been loosely described as being duc to a 'prominent conus region', it is characteristic of an infundibular chamber and it is brought into cven greater prominence in an oblique vicw (Fig 556), angiocardiograms again demonstrate its presence conclusively (Fig 550) Figurc 56 shows another cxample of a large infundibular chamber In both these cases the diagnosis was confirmed at opcration and the intervening fibromuscular diaphragm was punched away so as to relieve the stenosis, confirming that the obstruction was diaphragmatic and not long and tubular. That confusion and misunderstanding cust about what is rcally a simple tato of affairs is shown by Figure 57 As will be seen from the plain radiograph on the left, 'a', a characteristic bulgc duc to an infundibular chamber is present, 'H' 15 23 72

·6
a
C
55 To show the bulge on the heart contour formed by an infundibular chamber

·** 56 To show the bulge formed by an infundibular chamber.

·b 57 Erroneous interpretation of pressure changes observed in a case of infundibular stenosis with post stenotic chamber incorrectly wumed to be a long DAITO 08.15

·We
1
--
56 To show the bulge formed by an infundibular chambcr.

·3 b 57 Erroneous interpretation of pressure changes observed in a case of infundibular stenosis with posi stenotic chamber Incorrectly ostumed to be a long martor MC10115.

·76 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS radiograph taken at cardiac catheterisation in which two crosses have been marked, the top one shows the site of pressure change at the valve level and the lower one the site of change from an intermediate pressure to the high pressure of the right ventricle proper. Between the two crosses the pressure was constant at 19/10 mm Hg and it was assumed by those concerned that this represented a long tubular type of obstruction which would be very difficult to treat by direct operation The problem was referred to me for comment Obviously there is no evidence at all for a long stenosis, the pressure changes merely mark the low tension to be expected as the catheter tip traverses the infundibular chamber so clearly shown in 'a', the abrupt rise at the lower x marks the diaphragmatic-like stenosis before the body of the right ventricle is reached This error of interpretation is common and arises from the preconceived idea, almost superstition, which is engendered by the teaching that the stenosis of the infundibulum is typically long and tubular The falsity, of course, melts away before reasoned observation of the true anatomical state and of simple thought on the true nature of the pressure changes That the catheter can be of value in localısing the level of the stenosis is shown by Figure 58, in which the catheter tip is seen in 'a' above the pressure change and in '' below it, that this lies in the infundibulum and not at the valve is clear Figure 59 shows an electromanometric tracing obtained at operation from a proven case of infundibular stenosis and in the upper tracing can be seen the abrupt rise of pressure as the catheter enters the right ventricle. In this tracing, taken before the stenosis was resected, the pressure in the pulmonary artery is so low that it does not emphasise that the low diastolic pressure in the infundibulum is equal to that in the ventricle This is, however, clearly shown in the lower tracing made after infundibular resection It is also well shown in Figure 43 in the tracing made at operation on a case of combined valvar and infundibular stenosis, the pulmonary artery pressure is not much lower than the pressure in the infundibular chamber but the drop in diastolic pressure marks the transition from artery to infundibulum, the greater pressure change as the ventricle is entered indicates that the infundibular stenosis is the more important It must be emphasised that pressure observations must be made at operation to confirm the site and severity of the obstruction even though this may appear obvious from external examination of the heart, certainly the presence of two obstructions can be confidently elucidated only in this way Morcover, the effect produced by the operation on the stenosis or stenoses must be assessed at operation by further measurements and tracings Just as an infundibular chamber should be readily recognised, so can a valvar stenosis when the artery shows post-stenouc dilatation This applics only with certainty to 'pure' pulmonary valve stenosis in which thc artery can usually be seen on the plain radiograph (Fig 27, P 39), and shows up well in the angiocardiograph as diagrammatised in Figure 60A, it will be remembered that when

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58 Ure of ardial catheter to localise the ute of genosis

·78 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS PRE-OP. 1 ** 759 50 m + P.A. INF. RV. 11 POST-OP 59 Electromanometric tracing of infundibular stenosis the heart is very large the artery is pushed up so as to be horizontal and is therefore seen end on or foreshortened (Fig 28), this also is shown in Figure 60B I have only once seen in Fallot's tetralogy sufficient dilatation of the stem of the pulmonary trunk on a plain radiograph to indicate a valvar stenosis. A moderate or minor bulge is sometimes seen near the origin of the artery, but never enough to differentiate from a high infundibular stenosis If the type of valvar stenosis is as depicted in Figure 41, that is with a gencral moderate dilatation of the artery, the angiocardiograph may reveal a gencral ovoid dilatation (Fig 60C) similar to that seen in ‘pure' pulmonary valvar stencsis, although the artery is much smaller As a similar dilatation may be caused by a high infundibular stenosis it is important to try and assess whether the length of the dilated segment suggests that only the pulmonary artery is affected or whether it extends below the valve level, thus including the highest part of the infundibulum It may be difficult to decide this, especially as the amount of foreshortening of the artery varies with the amount it is pushed upwards by right ventricular hypertrophy It is then helpful to consider the shape of the proximal part of the opacity, a smoothly rounded end suggests a valvar stenosis and a pointed or conical end suggests a high infundibular stenosis (Figs 6D and E) Figurc61 is an angiocardiograph of an undoubted case of high infundibular stenosis with much general post-stenotic dilatation of the pulmonary artery and of its left branch This is also shown in diagram in Figure 60F, the dilated left pulmonary artery may be visible as a 'comma' on the plain radiograph It can occur in either valvar or high infundibular stenosis and so cannot be used as a diagnosuc fcature In Figure 62 a smooth globular termination is seen in a proven casc of high

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60 Dlagram to box interpretation of vious englocardiographic mpperences.
(For full description see toIt.)

·78 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS PRE-OP. Th. $ :1 1 1 50 :: -- PA. INF. R.V. 11 POST-OP 59 Electromanometric tracing of infundibular stenosis the heart is very large the artery is pushed up so as to be horizontal and is therefore seen end on or foreshortened (Fig 28), this also is shown in Figure 60B I have only once seen in Fallot's tetralogy sufficient dilatation of the stem of the pulmonary trunk on a plain radiograph to indicate a valvar stenosis A moderate or minor bulge is sometimes seen near the origin of the artery, but never enough to differentiate from a high infundibular stenosis If the type of valvar stenosis is as depicted in Figure 41, that is with a gcncral moderate dilatation of the artery, the angiocardiograph may reveal a gencral ovoid dilatation (Fig 600) similar to that seen in 'pure' pulmonary valvar stencsis, although the artery is much smaller As a similar dilatation may tc caused by a high infundibular stenosis it is important to try and assess whether the length of the dilated segment suggests that only the pulmonary artery is affected or whcthcr it extends below the valve level, thus including the highest part of the infundibulum. It may be difficult to decide this, especially as the amount of foreshortening of the artery varies with the amount it is pushed upwards by right ventricular hypertrophy It is then helpful to consider the shape of the proximal part of the opacity, a smoothly rounded end suggests a valvar stenosis and a pointed or conical end suggests a high infundibular stenosis (Figs God and E) Figurcoiis an angiocardiograph of an undoubted case of high infundibular stenosis with much general post-stenotic dilatation of the pulmonary artery and of its left branch. This is also shown in diagram in Figure 60F, the dilated Icft pulmonary artery may be visible as a 'comma' on the plain radiograph It can occur in either valvar or high infundibular stenosis and so cannot be used as a diagnostic fcaturc In Figure 62 a smooth globular termination is seen in a proven casc of high

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60 Duprum to show interpretation of various agiocardiographic appearances
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·1 61 High infundibular stenosis with large Icft pulmonary artery 62 High infundibular stenosis with rounded proximal end ·81 THE AVATOZTY OF CONGENITAL PULMONARY STEVOSIS 63 High infundibular stenosis. infundibular stenous but the shght extra length indicates this condition although it would be difficult to a clude & valvar stenosis with certainty before operation (Fig 60G) In Figure 63 the length of the pulmonary artery is sufficient to diagnose with far confidence that the proximal bulge is due to a small infundibular chamber, this is also suggested by the uniform density of the pulmonary artery Figure 64 shows a combined valver and high infundibular stenosis, the bilobed or cottage loaf appearance of the proximal shadow suggest thus und is supported by the slight but definite break in filling of the pulmonary trunk immediately dostal to the smaller upper part of the swelling (Fig. 60H) A lateral vich may help greatly in estimating ang atension below the valve level because in this view foreshortening to corrected. With an ordinary venous engrocardiograph the shadow of the superior vena ava may be superimposed on that of the pulmonary outflow tract iod it is therefore, better to use a selective technique in which the contrast medrum us injected via a catheter in the rght veninde. Figure 65 short such a ndiograph of a valvu stenosis in which it o ever possible to identify the lincar filhog defect due to the Faire itself and also the emergeat ja. Jonsson et al (1953) show some beautiful illustrations of selecdve angrocardiographic dentonstrations of the types of pulmonary stenosis The globular type of valvar stenosis is the commonest la Fillor's tetralogy and has already been described and has been depicted m Figure 42 It is shown ·65 Combined infundibular and valiar stenosis. The right-hand figure shows an enlarged vicwof the opacified stenouc region,cf Fig 60H.

·83 THE ANATOHY OF CONGENTTAL PULMONARY STENOSIS 65 Selective angiocardiogram to show yalvar stenosis diagrammatically in Figure God, instead of an ovord dilatation of the whole length of the malo pulmonary artery there is only a globular swelling at its bases Another feature that may point to e valvur stenosis is pertistance of the shadow within the valve globe or cone after the pulmonary artery hus emptied, this is, of course, a reflection of the obstruction present. At operation, recognition of a valyu stenosis may be easy and the cateda dready laid down for pure pulmonary valvur stenosis apply equally the most crucial test is actual palpation, either mth one finger or between finger and thumb, of the dome of the valve becoming hard and tense in systole. The gratet difficulty casts when a small globular valve is present, aut first glance the localised ·84 THE ANATOMY OF CONGENITAL PULMONARY STEVOSIS dilatation resembles persistence of the sinuses of Valsalva, perhaps somewhat smoothed out and suggesting dilatation distal to a high infundibular stenosis Careful palpation should, however, reveal that the stem of the pulmonary artery is under low tension all the time, whereas the globular first part becomes tcase in systole and relaxes in diastole The reverse is the case of the sinuses of Valsalsa are present, they seem to relax in systole and become slightly more tense in diastole. In addition certain other features of a high infundibular stenosis are absent. The bulge of a globular valvar swelling may often be seen and felt through the intact pericardium, but so can the bulge due to a high infundibular stenosis and it is impossible to differentiate the two unless the pericardium is opened Then the bulge of a high infundibular stenosis is seen to extend definitely below the level of the valve ring Usually it appears to be half above and half below the ring, as is shown by the presence of a thinned-out layer of muscle fibres on its surface, becoming rapidly thicker proximally where a definite depressed groove appears on the surface of the ventricle in systole This groove indicates the tethening of the outer wall of the infundibulum to the crista supraventriculars by the linear fibrosis which constitutes the maximum obstruction Moreover, although the sinuses of Valsalva are involved in the dilatation it is still possible to recognise their presence and structure. Palpation fails to identify the tense dome of the stenosed valve in systole, and although a jet-like thrill can be felt, it is not quite the same as with a valvar stenosis; it is usually not so fine and precise, its origin is less easily determined and it can be felt below the valve lezel if a finger is placed on the proximal part of the bulge, especially at the level of the constriction Even when the outer wall of the small chamber is thick enough not to form a bulge, light palpation will reveal that the wall is thinner than that of the main body of the ventricle and in this way the actual line of transition can be identfied In doubtful cases the transition can be found by electromanometric readings with a needle by making punctures on each side and narrowing down the gap, a catheter can also be uscd for securing a withdrawal tracing and the exact position of the stenosis idenufied by measurement of the length of catheter within the heart when the pressure change occurs The same technique may have to be used when there is a large infundibular chamber associated with a low stenosis but concealed because of good muscular development of its outer wall, when the outer wall is thin there is, of course, 110 difficulty Finally, if any doubt remains, a finger can be inserted through an incision lou down in the right ventricle and the exact site of the stenosis idenuficd It has been objected that the pattern of infundibular stenosis does not follos the descriptions gi en here, that such a descripuon is crroncous in affirming that the form of the stenosis is cmncnuy suitable for opcralise resection cxcept in a small proportion of cases in which there is cftreme hypoplasia of the outflou tract The success of operations for the direct relief of pulmonar stenosis must res!

·THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 85 on the correctness of the surgical anatomy gyen above. My apericace of direct operative relief of the stenosis in cases of Fallot's tetralogy mikos me quite con fident of the correctness of these observations, observations made on the living, functioning heart. Analyus of the actual results of the direct operations on the stenosis shows good or very good results in some 75 percent of cases (Brock, 1955) Such a high proportion of good results would be impossible unless the operations were well founded anatomically ·CHAPTER XI Forms of transposition; common ventricle T THIS chapter deals with a rather varied group of conditions in which pulmonary stenosis plays a part but is usually not the most important anomaly. Aorta and pulmonary artery both arising from right ventricle This is a good example of the inadequacy, which was mentioned carlier, of the term 'Fallot's tetralogy'. Clinically and radiologically a paucnt with this malformation may appear to be a typical case of the tetralogy, but the actual malformation demands separate classification Both ventricles are present, but the aorta arises wholly from the right ventricle, which also gives rise to the pulmonary artery Blood can leave the left ventricle only through a ventricular scptal dcfeci to enter the right ventricle and thence to the two great vessels Thercare cramples of lesser severity in which the aorta arises perhaps 90 per cent from the right ventricle and over-rides the left ventricle perhaps 10 per cent Somc blood can, therefore, pass directly into the aorta from the left ventricle, but the greater part has to pass through the scptal defect It is difficult to say at what degree of overriding a diagnosis of Fallot's tetralogy becomes unacceptable Arbitrarıls, it might be said that anything more than 75 per cent over-riding of the scptum moves the casc into a scparatc group This is because such a large degree of over-riding clearly indicates a dominint 86 ·TIDE ANATOMY OF CONGENITAL PULMONARY STUNOSIS 87 origin of the porta in connection with the right ventnde; in the typical Fallot's tetralogy the corti uaquestionably anses primarily from the left ventrcle, and 10 deed many think that the septal overlap is not real but is apparent or Illusory and results from the loss of fimation of that part of the aortic mg which has lost its support due to the septal defect. In fact, if one excises thus portion of the ventricular septum in e normal heart, it creates the impression of an over riding aorta if viewed from the right ventriclc (Lilleha et al, 1955) In these cases there is no difficulty in correcting the apparent dextroposition by suturing the margin of the septal defect to the aortic nng In case of genuine total or subtotal transposition of the corte in which it arises dominantly from the right ventride, it would be impossible to do such a repair to separate the outflow tracts of the two ventrides In fact if repair were possible it would, in contrast, result in total separation of the norta from the left ventricle. Total dextroposition of the aorta certainly demands separate classification, the higher degrees of dextroposition in which the aorta arisas almost entirely from the night ventride would appear to belong nther to this group than to a straightforward Fellot's tetralogy Certainly the prognosis is works, both without operetron and also after operation in which the immediate mechanical derangement may be profound and even fatal Thc stenosis may be infundibular but has been valvas in a sufficiently large number of cases to suggest that it may be the commoner losion in this type. The valvur obstruction may be of such high degree that it constitutes almost an atretia. The north and pulmonary artery in these coses may lie Bide by side like a twobarrelled gun, the aorta may then represent the nght reptilien dorta urising from the recess behind the arata supraventricularis which has already been mentioned as representing the outflow tract of the reptilian night sorte (7) Transportion of the great oessels with pulmonary stenoses It u do part of this monograph to give a full account of the development and inatamy of transposition of the great vessels, for tbus complex anomaly may cust without any form of pulmonary stentosus However it may also be accompanied by i pulmonary stenosi3 which is usually salvar but may be infundibuler The pulmonary artery lies directly behind the corta and is largely hidden both radiologially at operation und anatomically Common oentride (fusion of inflow portion of nght ventricle with left seatnde) Various forms of common ventade mry be met with in wluch there is also a pulmonary stenosis, but in the type selected here for speciel mention the leading feature is absence of : ventricular septum so that the infundibulum costs as a small andare of large common ventrcic (Fig 66) There is no ince of the inflow ·88 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS UU 66 Diagram to show common ventricle with a small, partly separate, right ventricular outflow tract, a low infundibular stenosis 1$ scen, portion of the right ventricle The infundibulum is always small and connects with the common ventricle by a small ostium which is similar to, perhaps identical with, the stenosed stoma usually seen in infundibular stenosis between the infundibulum and the body of the right ventricle. In addition there is usually an abnormality of the pulmonary outlet, either a high infundibular stenosis or a valvar stenosis, this may be of the nature of a yalvar atresia. This type must represent an early and severe abnormality of the bulbar fusion for not only is fusion incomplete but expansion of the bulbus is greatly retarded In one case, of a child aged 8 with moderate cyanosis and disability, the infundibulum, viewed at operation, was raised and quite distinct from thc common ventricular mass so as to form a small muscular channel or tubc about 0 75 cm wide and 2-3 cm long, just like a diminutive and separate bulbus cordis; clearly a high-grade atavism There was only a tiny proximal stoma connecting with the ventricle and distally a high-grade valvar stenosis amounting almost to atresia Life was supported by a small persistent ductus.

·TER XII Summary Direct operations for pulmonary stenosis, physiological changes due to direct operations NVESTIGATION of the morbid anatomy of pulmonary stenosis reveals that the obstruction is almost always duc to maldevelopment of the bulbus cordis, the the pulmonary valves, the protamal part is incorporated within the right ventricle to form the mfundībulum Stenosis may occur at vanous levels, but, conveniently, an be considered us affecting ather the distal or the prosmal part of the bulbis When the distal part is at fault, atresia of some portion of the pulmonary artery occurs, or pulmonary valye atresu or pulmonary valve stenosu Pure' pulmonary Yuyu stenosis with an intact Pentncular scptum is also due to malformation of the distal part of the bulbus Malformation of che proximal part of the bulbus giva nse to infundibular stenoses Combined valvur and infundibular stenoses imply that both the proximal and dutal portions of the bulbus arc et fault. Although the infundibulum exhibits various gnides of under-development, in every case the menumal obstruction is localised, being annuler or diaphragmats the manovest part of the channel may exhibit muscular thickening to its base, but the actual stenose or ostrum is surrounded by fibrous tissue, In older pauents this becomes progressively thicker, warty and even aldfied. The pormal systolic contraction may add a functional infundibular stenosis or may aggravite in casting anatomical one. 89 ·88 THE ANATOMY OF CONGENITAL PULMONARY STINOSIS 66 Diagram to show common ventricle with a small, partly separate, right ventricular outflow tract, a low infundibular stenosis Is seen portion of the right ventricle The infundibulum is always small and connects with the common ventricle by a small ostium which is similar to, perhaps identical with, the stenosed stoma usually seen in infundibular stenosis between the infundibulum and the body of the right ventricle In addition there is usually an abnormality of the pulmonary outlet, either a high infundibular stenosis or a valvar stenosis, this may be of the nature of a valvar atresia This type must represent an early and severe abnormality of the bulbar fusion for not only is fusion incomplete but expansion of the bulbus is grcally retarded In one case, of a child aged 8 with moderate cyanosis and disability, the infundibulum, viewed at operation, was raised and quite distinct from the common ventricular mass so as to form a small muscular channel or tubc about 0 75 cm wide and 2-3 cm long, just like a diminutive and scparate bulbus cordis, clearly a high-grade atavism There was only a uny proximal stoma connecting with the ventricle and distally a high-grade valvar stenosis amounting almost to atresia Life was supported by a small persistent ductus.

·CHAPTER XII Summary Direct operations for pulmonary stenosis, plrysiological changes due to direct operations NVESTIGATION of the morbid anatomy of pulmonary stenosis reveals that the obstruction is almost always due to meldevelopment of the bulbus cordis, the distai part of which forms the first part of the pulmonary artery induding the pulmonary valves, the proximal part is incorporated within the right ventrice to form the infidibulum Stenosis may occur at various levels, but, conveniently, can be considered us affecting ather the distal or the proximal part of the bulbus When the disual part is at fault, atresia of some portion of the pulmonary artary occurs, or pulmonary valve atresu or pulmonary valve stenosis 'Pure pulmonary valvar stenosis with an mtact ventricular septum is also due to malformation of the distal part of the bulbus Malformation of he proximal part of the bulbus gives rise to infundibular stentosus. Combined salvar and infundibular stenoses imply that both the proximal and distal portions of the bulbus are at fault. Although the infundibulum exhibits various grades of under-development, in cvery ase the meramal obstruction is localised, being annuler or drephragmaus, the narrowest part of the channel may ahibit muscular thickening in its base, but the actual stenosis or ostium is surrounded by fibrous tissue. In older padent this becomes progressively thicker, wity and even aldfied. The normal 19tolic contraction may add a functional infundibular stenosis or may aggravate I costing natomial one. 89 ·90 THE ANATOMY OF CONGENITAL PULMONART STEXOSIS In one type (hypoplastic) the whole of the infundibulum is atrophic and the pulmonary channel is totally inadequate, although even in this type there is a secondary zone of maximal fibrous stenosis or there is a valvar obstruction Where the infundibulum is not so hypoplastic it is convenient to classify the types on the basis of the level of the maximal obstruction This may be 'high', 1c immediately below the valves, no infundibular chamber is formed. At other levels it may be 'intermediate' or 'low', in all of these a post-stenotic dilatation occurs giving rise to an infundibular chamber which may be prominent citernally if its outer wall is deficient in muscle It is imperative to recognise that in all types, although the infundibulum may be so much smaller than normal as to give a reduced pulmonary channel, this is usually adequate and the effective obstruction is always annular or diaphragmatic In the simplest and rarest form the obstruction is at the junction between the body and the infundibulum of the ventricle, the cavity of which is then virtually separated into two parts by a muscular septum perforated by an ostium with a rigid fibrous margin In this type there may be no ventricular septal defect, in all the others a scptal defect exists In a proportion of cases of Fallot's tetralogy, probably between 30 and 40 per cent, the effective obstruction is not infundibular, in spite of the infundibulum being small, but is valvar In some 20 per cent an infundibular and a salvar obstruction co-exist These observations on the nature of the actual obstruction arc fundamental in considering operative treatment The direct operative relief of pulmonary sichosis This is no place to dcbatc the relative values of the indirect anastomoric operations and direct rclicf of the obstruction itscif, this has been discussed clscwhere (Brock, 1954, 1955) It is sufficient to point out that if the actual obstruction can be relieved thc hcart is directly bencfited and the mechanics of the circulation are not further complicated by an aruficial ductus arteriosus. In 'purc' valvar and 'purc' infundibular pulmonary stenosis there can bc no doubt that valvotomy or infundibular rescction are the operations of choicc If the obstruction is not relicvcd and a short-circuiung operation donc, no relief is given to the burdened right ventriclc and an additional strain is thrown on the Icft ventriclc The alrcady or crta cd night heart has to cope with a further increase of circulating blood and sooner or later fails Direct rclicſ of the obstruction, whether it be valsar, infundibular or the two combined, is also feasible in a very high proportion of case; of Talloi's tetralogs. The anatomical basis for thcsc procedures has been set out in the preceding: chapiers and summarised abosc and its truth has been abundantly confirmed during the cxperience personally gained in 168 direct crerations on 1 allor's ictralogy during the last 7 years. That the anatomical basis is soundly converses is also proven by the high percentage (somc 75 per cent) of find or excellent ·91 THE ANATOSTY OF CONGENITAL PULMOLARI STETOSIS cm 0 67 Resection of a segment of crusta supraventricularis by mcans of a spur punch. This, by disrupting the sphincteric like acalon of the infundibubur muscle may destroy the control mechanism result obtained The only lesions for which a direct operation is not feasible are those of tricuspid atresia pulmonary atresia and severe degrees of pulmonary outflow hypoplasia, especially in infants and young children. When the crista supraventricularis is lovolved in the stenosis the question arbas of resecting part of it to increase the lumen. This is possible us a closed procedure by using a punch forceps with a terminal bate (Fig 67) Whether it is good surgery to divide thus importent muscular structure is perhaps doubtful, it can be very effective in relicvmg the infundibular stenosis When it is being resected two structures are vulnerable; one is the septal cusp of the coruc velve which lies above, the other is the right branch of the atrioventricular bundle This noms down the septum from the posterior part of the sepul defect well behind the crise and would be damaged only if an instrument were directed well backwards It has never been damaged on the numerous ocasions I have performed punch resection of the consta Direct operations on the stenosis are better done at an arly age to that the pulmonary outflow tract aan grow with the patient. Development must be progressively severely arrested if the stenosis is tot relieved, for in additon to the stanou becoming relatrcely more severe us the patient grom older, it becomes absolutely more severe us a result of daily wear and tear on the stenosed passage. Ultimately the obstruction may become complete or so nearly complete us to be virtually so Valvotomy allows progresave dilatation of the main pulmonary artery and of 15 broches, infundibular Itsection, by Correcting the tethering of the walls of the infundibulum by the fibrous ning which loops out from the crista ·92 THE ANATOMY OF CONGENITAL PULMONARY STEXOSIS supraventricularis, allows growth and expansion of the channel as the rest of the heart grows In other words, normal growth and progressive improicment are favoured In patients in the late teens and twenties, in addition to permanent arrested growth of the infundibulum, secondary narrowing has occurred from progressic fibrosis Direct operation is less favourable in these older patients when the stenosis is high, it is more likely to be favourable when the stenosis is lou because post-stenotic dilatation has produced a good-sized infundibular chamber. The only disadvantage is that if the muscular wall of the distal part of this chamber is thin and atrophic it may stretch under the influence of the increased pressure and flow, and secondary functional pulmonary regurgitation may develop (scc Chapter XIII). That increase of size of the pulmonary artery does in fact follow a direct operation has been observed in several cases when a second opcration has been performed Thus, in a young boy aged 5 years the pulmonary artery was less than I cm in diameter in association with a valvar stenosis Valvotomy was followed by a good result for 2 years and then cyanosis and disability began to return At a second operation 5 years after the first one the pulmonary artery was found to be of normal size, the valvar stenosis had been corrected, an infundibular stenosis was present and was successfully resected This is an important observation for it means that cven though thc pulmonary outflow tract is severely under-developed, it can be restorcd to full growth by a successful direct operation It should then be possiblc at a sccond operation, should it be necessary, to close the ventricular scptal defect without fear that the pulmonary channel could not carry the additional flow of blood if the stenosis is totally removed This must always be a fcar in certain cases of Fallot's tetralogy now that technical developments allow simultancous rcscction of the stenosis and closure of the scptal defect Although a proporuon of cases will be primarily suitable for such a one-stage definitive curativc procedure, there will always be a proportion in which the pulmonary stenosis will have to be relicved as a first stage and the septal defect closed as a second stage It has been suggested that the simple direct operation for the relicſ of salvar or infundibular stenosis in Fallot's tetralogy is incomplctc and therefore obsolescent It is doubtful, in the light of thc abouc obscrvations, if this is correct Correction of the right-to-left shunt In addition to lessening cyanosis and disability by increasing thic blood-flo: to the lungs through the normal channel, direct opcrations on the obstruction act bencficially by another mechanism Part of the cyanosis and disability is duc to dcficient blood-flow to the Funra, part is due to the right-to-lcfi shunt through the septal defect in pulmonary salvar stenosis with a persistent foramen osale there can be no question at all or this latter mechanism because cyanosis may appcar onlı after many yer and can ·THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 93 be corrected completely by successful valvotomy In malformations of the Falloe's tetralogy type in which there is a ventricular septal defect, a similar effect is produced (Fig 68) Thus, if there is considerable obstruction to the outflow into the pulmonary artery, a large part of the output of the night sentricle inevitably pastes into the aorta with conaderable minng of venous and arterial blood. If the obstruction to the pulmonary artery, whether valvur or fnfundibular, relieved, e greater part of the output of the night ventricle can pass to the lungs and a correspondmgly smaller amount is dextled mto the aorta, the uteriovenous mining us, therefore, reduced. If the optimum relief of the pulmonary stenosis is obtuned by operation the nght to-left shont will be completely abolished, cyanosis and disability will be completely relieved. In some cases the shunt is not only corrected, it may be reversed so that it A B 68 Dlagram to show the effect of direct relief of the pulmonary stenosu in Fallots tetralogy in correcting the right to-left shunt in addition to improving the pulmonary blood flow A Pulmonary itresia total xhunting B Fallor's tetralogy, partial bunting C. After operation, lesened shunting becomes left to-night; the pulmonary flow being slightly greater than the systemic flow In ocasional ases we have observed considerable reversal of the shunt so that the pulmonary flow becomes too great. In some of thesc thc pulmonary artery pressure has been slightly raised as a result of the increased flow, not from increased resistance. Thus in one ause the oxygen saturation rose from 86 per cept to 98 per cent, thc pulmonary flow increased from a balf to double the systemic flow the pulmonary artery pressure rose from 14/7 mm. Hg to 38/12 mm. Hg Far from a severe rise in pulmonary artery pressure following direct relief of the pulmonary stenosis the rise in pressure is more often disappointingly small, modeed it may nse so little that the clinical result would appear to be inevitably unsatisfactory In fact, with crea a titial rise in pressure in the pulmonary artery the clmical result may be acellent, demonstrating that it is pulmonary flow rather than pressure that matten In many such ases the peripheral pulmonary raistwce is so low that no prewure nile occun The following cose serva un perfect Euxmple of this The patent host young man eged 19 years and us bad a case of Fallot's ·94 THE ANATOMY OF CONGENITAL PULMONARY STEYOSIS tetralogy as it is possible to meet. He was quite incapacitated and was whicle into the out-patient clinic in a chair He was so cyanosed, distressed and ill that It was necessary to admit him to hospital at once In due course he underwent operation and a pulmonary valvotomy was done Figure 69 shows the catheter studies in July 1951 before operation and in November 1954 after operation If the pressure curves are examined it will be found that there is but little change. the right ventncular pressure is 75 mm Hg before and about 90 mm Hg after operation, the pulmonary artery pressure was rather below zero and was between ES 4751 75 l honetan 50 th flbare Before Valvotomy O. Capacity 263 mi i (Hb 1 40 ) Arterial o San grau Pul Blood Flow 171 min Sys Blood Flow 601 min R - L Shunt 431 min 51* 25 mmHg 710 LLO AORTA "mm. HRV il 217TD]Hg List 25 1 1 54 100 3 1 50 Alier Valvotomy 0. Capacity 209 ml (Hb 109",,) Arterial O, Sain 96". Pul Blood Flow 771 min Sys Blood Flow 56 min London Shunt 211 min -10 مسلسل Hg 02 B.A mm R V mm P A Hg 69 Catheter studies before and after successful pulmonary valvotomy in Tallot's tetralogy (For description and discussion sce text) zero and s mm Hg after operation The clinical result, however, kas 35 perſeci as one could wish All cyanosis and disability werc rclicvcd, he gained some 3 stone in weight and from being a complete invalid is now ablc to do a full day's work This improvement is rcficcted in the other catheter findings gren in Figure 69 Thus the artenal ovygen saturation has risen from 54 per cent 10 95 per cent (hacmoglobin has fallen from 140 per cent 10 108 per cent), more striking still is that thc pulmonary blood-flow has risen from 1 7 litres per minute to 7 7 litres per minute, in fact the sight-to-lcft shunt of 4 3 litres per minuic has been changed to a lcfi-10-right shunt of 2 1 litres per minute luas difficult to imaginc a more striking examplc of the important part played by the peripheral pulmonary resistance in influcncing blood-flow. It is possible that in later years we may obscric an increase in peripheral pulmonary resistance accompanied by a risc in pulmonary artery pressure anila diminution of pulmonary flous, perhaps even rcsersal of pulmo'l.rs forse an. recurrence of the right-to-lefi shunt and cyanosis I his, howeser, rem" for the future in the meantime the prospect of routine ullcyful clorure of the ·THE ANATOSTY OP CONGENITAL PULMONARY STENOSTS 95 vetitniculur sepul defect under direct vision in these cases (Brock, 1954) makes it probable that the onset of such secondary changes may be entirely prevented. Moreover the ability to close the ventricular septal defeat will entirdy remove maica and Hmitatons in regard to too generous relief of the pulmonary stenosis The need to leave some protection for the pulmonary arculapon will no longer remain and the stenosis can be dealt with us radically as possible under the name direct vision. Ansing further out of this question of alteration of the night-to-left sbunt after successful operation for the relief of the pulmonary stenotic element in Fallot's tetralogy (velvotomy or infundibular resection, interesting immediate secondary phynologial changes may be observed Thus, on one occasion at an operation in which infundibular resection had beco completed, the anaesthetist semuasked that the peripheral blood presure had fallen and the pulse was poor, at first this was thought surpristng because an excellent pulmonary blood flow could be felt us judged by palpation of the pressure and flow in the polmonary mmHg 150 100 AORTIC PULSE 50 ON OFF 70 Aortic blood preture incing in a case of Fallot's tetralogy after lofundibular retection When the pulmonery outflow trawus compressed the portic pret pure roze to mm. Hg and fell again when the pressure was released the demooostruttog variations in the right co-left shumt. atay The more usual observation is that deterioration in the patient's general condition 13 accomparued by disminution in the pulmonary flow, 1.e there 13 general depression of the arculation. In contrast in this are there was selective depression of the systemic circulanon. This suggested that the increased pulmonary flow was at the campcase of the syuemic output, and thus was confirmed quite simply by observing the aortic and radul artery presure while a frager was pressed on the polmonary outlow tract and then reluxed. Figure 70 shows the effect clearly in an electromanometric triang This mechanista intelligible if one accepts that the combined ventricular output cannot immedutely increase to compensate for its redistribution, thus if the pulmonery flow lacreases the systemic low must decrease by about the same imount. The only way the ventricies an correct this state us by increasing their output and this may be difficult in the early stages after the afficiency has been mpared by a surgical intervention This a doubtless also the explanation of another phenomenon observable, especially in young children, during the first few days after operation, that is the Occurrence of systermc hypertension. Soon after operation the peocat may show endence of grauy dumnushed peripheral blood flow us seen by pallor, some ·170 160 150 1170 1160 2150 140 130 120 140 130 SYSTOLIC 120 110 100 wa 110 100 90 Left thoracotomy infundibular resection 90 130 120 130 110 120 110 100 100 90 DIASTOLIC 90 80 80 70 60 AM PM 12 AM 2 3 4 70 60 5 6 7 8 9 10 11 2 3 5 50 12 + SO 24 25 JULY 1951 26 29 28 JULY 5 AUGUST 9 10 AUGUST 71 Blood-pressure chart after a direct operation on a patient with Fallot's tetralogy showing the temporary rise in blood-pressure often obscried ·THE ANATQATY OF CONGENITAL PULMONARY STENOSIS 97 CytoSD und poor pulse volume in contrast the blood pressure is high and may reach 200 mm Hg systolic or even higher This 13 a remarkablc occurrence in a young pedent who has rest undergone a major ventricular cardiotomy, it would be not unreasonable to pect hypotension rather than hypertension In one child the systolic pressure 24 bours after operation rose as high as 270 mm Hg, a figure which cused considerable alarm as to its effects on the heart and concem as to whether some gross accident had occurred The aplication seems to lie in en canggerated response to the redistribution of the ventricular outpur us meationed above the only way the ventndles could themselves correct the diminished systemic flow would be to increase the stroke volume. Tho a scarcely be donc so soon after ventricular cardiotomy Com pensation is achieved by another mechamsm-peripheral vasoconstriction, this an help to mantum an adequate coronary low while cutting down the less important peripheral arculation. The peripheral constriction is obvious clinically Figure 71 shows the blood pressure chart in such a case; the phase of secondary hypertension and then gradual recession to normal pressurc us shown. The secondary nise u best seen in young children but may be observed at all ages. In addition to the physiologial and clinical interest of this phenomenon there is un important practical bearing After cardiotomy for pulmonary stenosis wich 1 ventricular septal defea (Fallot's tetralogy) It would be easy to be content with i normal or subnormal blood pressure; it could well be thought that this was to be expected. Actually this should give grounds for alarm, for it would indicate that the arculapon s not being readjusted satisfactorily Unless there is no doubt that the patient's condition is quite satisfactory it is better to take steps to raise the blood pressure, Le by transfusion, posture and, if necessary vasoconstrictor drags ·CHAPTER XIII Control mechanisms in the outflow tract of the right ventricle T HE function of the right ventricular outflow tract is somewhat more complicated than is generally thought Indeed, it is doubtful if much thought in general is given to it, the usual conception is that of a simple muscular canal which contracts to aid the expulsion of the blood it receives in diastole In actual fact, the function is more sensitive, more labilc, than this and is particularly concerned with a mechanism exerting a control on the pulmonary blood-flow Although this is a function in the normal heart it assumes grcater importance and is more readily demonstrable in the abnormal heart, especially when there is some form of pulmonary stenosis The anatomy of the normal right ventricle has been described (Chapter III), and Figure 16 (p 19) illustrates the way the infundibulum stands out in a manner which shows it is anatomically partly separate from the rest of the right ventricular muscle mass and which suggests it may also bc functionally somcwhat separate. This arrangement of the infundibulum was fully explained by simplc rcfercnce to its development It will be rccallcd (Chapter I) that in thc fish and the amphibian heart the bulbus cordis cxists as a separate part or chamber which is not seen in the mammalian heart, in which it loses its identity by becoming absorbed into the musculature of the outflow tract of the right ventricle 98 ·THE ANATOMY OF CONGENITAL PULAIONARY STENOSIS 99 The fonction of the murdibulum Secing that structure is related to function, the obvious anatomical difference between the infundíbulum and the rest of the nght veatndc suggests that this may be related to different function. To Keth (1904) belongs the credit of boring drawn attention to this He states, 'The great development of the bulbus utenlosus in gill-breathmg vertebrates is due to the peculiar nature of their arculation. The heart is primarily a respiratory pump, the ventride throws its lond into the short sorts leading to the gills To be able to receive the ventricular load md to force it onruds, that rossel is endowed with enormous elastaty to that no vulves within it could be mechanically competent were they not fumehed with a muscular or clastic support, such as is provided by the bulbus urteriosus. The musculature of the bulbus, like that of the aorta, is always in action but most so m diastole of the ventricle. In every way the pulmonary artery resembles the short gill sorts of fishes of which it is the functional representative h ur breathing vertebrates Keth then goes on to suggest that in man the pulmonary valves are rendered competent only because they are reinforced by the musculature of the veninde which extends up to them. In support of this bc quotes some experiments carried out by Gibson (1898) in which he showed that the pulmonary valves allow regurgitation if they are exposed to the weight of more than a certain column of Aud This regurgitation could be controlled by constricting the pulmonary artery by tying a cord round it cxactly at the attachment of the valves Gibson felt that this showed clearly that the relative to competence of the valves was aused by distension of the clasac artery Tested in the name way the soruc valves dever allowed any escape These observations led Gibson to suggest that a mechanism of readjustment to prevent regurgitedon o desirable in the pulmonary arculation and Kath supports this view He feels the fibras of the bulbus artenosus in lower vertebrates are not truly discharging but regulating fibres that maintain their toniaty when the true fibres of the reutacke bave passed into a state of diastole when the right heart is distended the arcular fibres round the base of the pulmonary artery form a functional Stoctor at the commencement of ventricular systole between the infundibulum and greatly dilated artery and are a factor that must be considered in explaining the production of pulmonary systolic bruits I have repeated these experiments of Gibson and have been able largely to reafy his findings and certunly to verify his condusions The heart from a freshly killed dog was used and long lengths of glass tubing were tied into the aorta and prolmonary artery and then filled with water The pulmonary valves soon become incompetent and permit regurgitation. The aortic valves support a much hugher column but they too become incompetent, the findings thus differ in this respect froca those of Gibson who stated that the nortic valve never allowed any csapt. The relative efficiency of the two systems is shown by the simultaneous hegnt of the water columns above each valve; in one cxperiment the aortic column wu so com tod the pulmoners column was 20 cm Wien a flat tape was tighteaed я ·100 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 72 Photograph of a dog's heart in which a column of water in a glass tube tied in the pulmonary artery is causing gross distension of the pulmonary valve ring and of the musculature of the infundibulum 1 round the pulmonary valve ring the onset of regurgitation could be greatly delayed, as shown by Gibson If the tape is released when the valves have been supporting a high column of water in this way, the weakness and inability of the pulmonary ring and the infundibular musculaturc to support the valves is strikingly seen, gross dilatation of the sinuses of Valsalva and of thc pulmonary ring is seen at once (Fig 72) I have also carried the observations a stage further In an anaesthctiscd dog the heart was exposed by a trans-sternal incision and the roots of the great vessels identified One needle was then inserted into the pulmonary artery and onc into the right ventricle so that simultancous electromanometric pressure recordings were made. The pulmonary artery was then partly occluded by a clamp so that thic pressure rose, regurgitation at the pulmonary valve occurred rapidly, thus ynth an initial pulmonary artery pressure of 16/14 mm Hg regurgitation occurred when the pressure reached 26 mm Hg systolic In contrast, when the same obscrvation was made on the aorta regurgitation did not occur until the systolic pressure was over 300 mm Hg Thus the initial aortic pressure was 98 81 mm. Hg, there was no regurgitauon at 261/180 mm Hg, regurgitation began ai 316/163 mm Hg and was more severe at 320 mm. Hg. Attempts were made to show that thc onset of pulmonary regurgitation could be retarded when the tonus and power of the right ventricle was enhanced by calcium chloride or by adrenaline, although this appcared to be the case the results of the cxperiment were not enurely conclusisc, adrenaline seemed ccr- ·101 THE ANATOMY OF CONGENITAL POLMONARY STIINOSIS tunly to delay the onset of regurgitation. (I am indebted to Dr P Fleming for desistance to making these observations) Walmesley (1929), in Quan s Anatomy, states that the developing myoardrum reaches the trunsition of the bulbus into the truncus and then diæppears in the distal part of the bulbus even before it is differentiated into recognisable musde tissue. This retrogramion of the bulbus myocardium is a significant feature of all vertebrate bearts, it is probably to be related to the replacement of a muscular sphincter control of the ait tube from the heart by a purely mechanically valvular control. This condusion that the control of the pulmonary outflow us a purely mechanical function of the valve cusps and is not supported by muscular action in the mammalian heart is almost certainly incorrect, it is certainly incom plete. There is much to support Kath s view of the probable function which the muscle of the infundibulum subserves If Kath a view is correct, the infundibulum should not contract as a whole to expel its contents but a wave of contraction should pass along it; almost a peristaltic wave. I have watched the action of the infundibulum On many hearts, normal and abnormal, exposed at operation, under favourable conditions it is possible to see quite deady a progressive wave of contraction and relaxation paning up the infundibulum. The conditions are, however, not very favourable for recognising thus and even less favourable for demonstrating it. I was therefore, cager to study the repid anematographic studies of the heart made by Prinzmetal (1952) in which the heart contractions are photographed at up to 1,000 frames a second and are projected at the standard rate of 16 frama a second, thus permitting detuled lasurely study and demonstration of cardiac movements that are otherwise imposible to analyze. Prinzmetal s studies bave been wholly directed to the atrn, both in normal function and in arrhythmus In hus films, however the whole heart an be seen and in certain places it is possible to observe qurte dearly the action of the mafundibular portion of the right ven tride up which a wave of contraction passes, preceded by a wave of distension or relaxation. It is unfortumtely not possible to reproduce in still pictures what can be seen in the motion picture. If it is true that the musculature of the infundibulum tuos thus controlling action on the output of the right ventricle and the stability of the pulmonary valve mechanin, it follows that in addition to actual wave of muscular contrac tion und relaxton playing putmuscle tonus must also be important. It is possible to make observations in pathological clinical states which tend to support this supposition that Flying tanus in the right ventricular outflow tract 1 of functional importance. The mundibulum in pulmonary stenoses A characteristic clonial feature of Fillor's tetralogy is venation in the degree of cyanosis and diability, often from day to day, depending on cnvironmental conditions, and also the occurrence of attacks of deep Cynosu ind unconsciousnes.

·102 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 73 Diagrams to show the effect of variations in form of the pulmonary outflow tract, as the tonus increases-diagram on the right-less blood goes to thc lungs and more is shunted into the aorta These attacks are of ill-omen and may be fatal. I suggest that there is a simple explanation for their occurrence, namely incrcase in tonus of the infundibular musculature Thus, if the tonus of the already diminutive outflow tract increases, the narrowed lumen becomes smaller as if by sphincteric action, less blood passes to the lungs and at once the right-to-left shunt increases and more venous blood enters the aorta (Fig 73) The cyanosis is, thereforc, worsened in two ways and it is not surprising that unconsciousness occurs when the stenosis is initially severe, even a small increase in tonus will be serious and it is just in those patients with severe stenosis that severe, frequent and perhaps fatal cyanotic attacks occur Presumably the tonus must relax as cyanosis becomes profound and as the coronary blood-flow becomes increasingly inadequatc, general cardiac tone would inevitably fail as the coronary flow became poorer. The milder variations in cyanosis depending on climatic and other conditions may also be duc to variations in tonus of the infundibular muscle We have been able to obtain actual direct cvidence of variation in tonus of thc infundibular musculaturc, this has emerged from catheter studies made beforc operation and at the time of operation Thus thc tracings shown in Figure 74 can be explained in no other way In the upper tracing, made at cardiac cathcicrisation, a diagnosis of infundibular stenosis was made, it can be seen that there is only one change in the systolic pressure although the drop in diastolic pressure indicates clearly when the catheter passes from the pulmonary artery through the valve to cnter the infundibulum. The lower tracing was made at opcration and a double pressure change is shown, onc at the valve level and one at the infundibulum Combined valvotomy and infundibular rcscction were needed The only satisfactory explanation of this is that the tonus of the infundibular muscle was greater at cathctcrisation Rodbard and Shaffer (1955) have reported interesting and corroboratic observations made at cardiac catheterisauon on cases of Fallot's tetralogs. I licy ·103 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS sor GOH 40 JOH 10H Гrer\V*tiith AT CARDIAC CATHETERISATION 1005 sot 60+ 40 20 O AT OPERATION 74. The top tndng taken at cerdiac atheterisation thom a single stenosis infundibular The lorrer truens we taken at operation and two stenoses valvar und infundibular are shown. The only aplanation is that at cardiac antbeterin tfon the infundibular muscle wus in greater tonic contraction. observed that in 10 out of 13 cases the pressure in the right ventricle and in the Infundibular chamber began to nse together for a part of the election phase but the infundibular pressure then begro to fall, even though the rght ventricular pressure continued to rise. These findings suggest that the infundibular stenosis becomes more severe during ventricular systole and Rodbard and Shaffer comment, 'Phylogenetic and electrocardiographic evidence suggests that the infundi bular portion is one of the last portions of the right ventude to become activated during systole They also comment that in the prevence of a ventricular septal defect thus dynamic sequence may well be a fuctor in the production of the frequently observed bidirectional shunt In early systole, shunt flow would tend to be from left-to-right. Then contraction of the mfundibulum increases the restance to pulmonary flow decreasing the shunt or even reversing it. Certamly in Fallot s tetralogy it is likely that the degrec of pulmonary stenosis LOCTCUSGS during the later phax of ventricular systols, causing the right to-left shunt to become progressively more severe Figure 75 illustrates a posuible trip that exists in the atheter diagnosis of infundibular stenosis Thus & withdrawal trang seemns to show the pulmonary urtery pressure, then the diastolic pressure falls suggesting that the mfundibulum is bemg tratrsed before the final major change to the high ventnculær pressure. A diagnosis of infundibular stenosis was made. At operation a simple pulve stenosis ou found there was no infundibular stetos The coplanation is that the first part of the traing shows the pressure in the night pulmonury utery;

·104 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS 75 Mistaken catheter diagnosis of infundibular stenosis The apparent infundibular tracing is from the pulmonary trunk in which the low diastolic pressure is due to a Venturi effect the next part with a low diastolic pressure was actually taken from the main pulmonary artery and was due to a negative pressure in the artery and does not represent an infundibular chamber, it can be seen that it is lower than the true right ventricular diastolic pressure Dr L Brotmacher has pointed out to me that when the electromanometric tracing is studied with a synchronised clectrocardiogram it can be observed that the low diastolic pressure in the pulmonary artery corresponds with the upstroke of ventricular systole, the explanation being that it is a Venturi effect due to the rapid flow of blood through the narrow orifice Elmslie-Smith et al. (1956) have also made similar observations with simultaneous reading of the intracardiac electrogram and pressure pulse in patients With pulmonary stenosis which they have found helpful in locating the level of the stenosis Secondary infundibular stenosis after pulmonary valvotony Somewhat allied to the question of varying tonus in the infundibulum is the phenomenon of the development of a secondary infundibular stenosis after pulmonary valvotomy in cases of valvar stenosis with a normal aortic root, was fully described and discussed in Chapter VI That the same development of a secondary infundibular stenosis can in Fallot's tetralogy after a successful valvotomy is shown by the obscrv made in Figure 76 Experiences in punch resection of infundibular of In tctralogy also provide another indication of the pro ca of the infundibular muscle Thus my ordinary pra poruon with a circular punch On occasions, ho type punch resection has appeared to be inadequatc I ich remorca segment of the crista supraventricularis be immediately followed by a great incrcase in flow sien 2 cm in 1 ·wil 105 THE ANATOMY OF CONGENITAL PULMONARY STENOSTS POST OPERATION PRE OPERATION -75 TB 50 60 20 علم mmly r mmHс 75 menem from Firm E - clow 0 0 TADH mmHg PAT R. V PA INF R. V 76 Electromanometric tracings before and after pulmonary valvotomy in a case of Fallot's tetralosy to show the development of secondary infundibular stenou Just as may be seen in case of pulmonary stenous with intact ventricular septum. Thet a true Fallot's tetralogy was present is shown in the pre-operative tracing in which the catheter has entered the aorta. pulmonary artary in fact thc pressure and flow may be excessive This cannot be entirely explained by actual removal of the infundibular stenosis, it is more likely to be due division of the sphincterc muscular mechanism and therefore complete failure of its controlling action on the outflow tract. Discussion It is submitted that enough evidence has been put forward to substantiate the hypothesis that controlling mechanism custs in the musculature of the night ventricular outflor tract. When Kath anginally put forward this view he recommended it to clinicans for their consideration and for application to such problems es might appear pertinent. He himself suggested only that it might be rasponsible for some functional systolic pulmonary bruts and lamented fulure of dmcans to pay any attention at all to the facts put before them by the anatomist nad morphologist (Kath, 19048) Basically from the point of view of pure science alone, it is important to recognise the presence of such an important function is a mechanism for 10 fluencing and controlling the pulmonary outflow from the right veatride. There ure other applications than the single one mentioned by Kath For instance it is noteworthy that the pulmonary valve regurgitation occurs rapidly when the pressure in the pulmonary artery rises only slightly This may well be an important mechanzo causmg or aggtiyating cardiac distress following arduc operations, eny mechanical interference causing pressurc on or distortion of the pulmonary artery could be very uodairable and could throw a grat extra strain on the nght veatncle. In the commoner ause of reused pulmonary artery ·106 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS pressure there is time for compensation to occur, the secondary muscular hypertrophy of the right ventricle simultaneously improves the force of the muscular support of the valve mechanism and so cancels the tendency to regurgitation Eventually, however, as is so well known, decompensation occurs and pulmonary regurgitation develops In perhaps its commonest form this is seen in the pulmonary hypertension due to mitral stenosis and the eventual onset of pulmonary regurgitation as shown by the Graham Steell bruit, or in the pulmonary hypertension secondary to a ventricular septal defect Acute strain may be caused in association with direct operations for pulmonary stenosis For instance, after infundibular resection in cases of Fallot's tetralogy an incision has been made into the outflow tract of the right ventricle and part of the wall has been cut away, it is not surprising that some impairment of muscle tone follows and temporary pulmonary regurgitation can occur. This may be recognised by the diastolic murmur for some days after operation, the murmur gradually fading as tone recovers and compensation occurs Although pericardial friction may mimic the murmur of valve regurgitation there can be no doubt that true temporary regurgitation occurs It is more likely to occur in a significant form if there is a thin-walled infundibular chamber distal to the stenosis and if this is suddenly exposed to a high pressure from too generous relief of the stenosis If this is so the thin muscle in the infundibulum at the valve level may stretch considerably, thus causing quite severe and prolonged pulmonary regurgitation I have certainly seen this in one case in which the pulmonary artery systolic pressure rose to 40 mm Hg, this is the only severe example I have seen in cases of infundibular resection Although it is put forward as an objection to the direct operations for Fallot's tetralogy it is not a serious one because of its rarity, provided the stenosis is not relieved so much that the thin infundibulum receives the full ventricular pressure I have recently seen a quiet pulmonary diastolic murmur develop during pregnancy in a young woman who had undergone successful open resection of a pure infundibular stenosis one year before Presumably this was due to the increased blood-flow of pregnancy in the presence of the rather thin-walled infundibular chamber which had been present distal to the previous stenosis The right ventricular pressure, as such, had been reduced to normal ·REFERENCES OTT M. E. (1936). Atlas of Congenital Cardiac Disease, New York. ANDY K Dad CAMPBELL, M. (1949) Guys Hosp Rep 98 18 - BRONTON WD CAMPBELL, M and GARDNER F (1950). ibid, 99, 110 TER, J S (1953) Frazer a Manual of Embryology, London UNT S G, McCORD M C., MUTLLER H, and SWAN H. (1954) Circulation 10 161 C, R. C (1954) Le Powonon et le Caur 10 617 -(1955): Bru med Bull, 11 189 WN, J W (1939). Congenial Heart Disease, London PBELL, M (1953). Brut Heart J 15, 462 - and BROCX, R. C. (1955) idud , 17, 229 ZELOT E., D ALLANES, F, DUBOST, CL. MÉTLANO C. DURAND, M, and DUDOST C. (1952) San HDp Pans 28 877 LILLE SMITH D, LOWE, K Gmd HILL, J GW (1956) Brut Heart I , 18 29 LOT A. (1888) Marseille med. 15, 418 IR,E. (1931) A Manual of Embryology London SON, G A (1898): Diseases of Heart and Aorta London. IL, A. (1903) Morph 96 31 113 ARIO,J LIND J md WEALLIUS C. (1954) Bnt Heart , 16 109 LHAN E. (1954). thorac, Surf 28 109 NTUR, W (1812) Med obs and 194 , 6 291 ASSON G BRÓDEN B. and KARNELL, J (1953) Acta Radiol (Stockh.) po 547 TH, A. (19041) Lancet 1, 555 (1904b) ibd i 629 (19040) ibd 1 703 - (1905):9 Amat (Lond.), 19 14. - (19092) Lancet : 359 - (1909b) ibd 1 433 (1909c) ibad : 519 - (1924). ibid., 1 1267 (1933)Human Embryology and Morphology London. COLIN J W CONNOLLY, D C ELLE F H BURCHILL, HB, EDWARDS, JE, bod Woons, E. H. (1953) Corculation, 8849 LOHEL CW COHEN M WARDEN H. ERBAD RĆ AUST J B, DEWALL, R. A und VARCO R L (1955) Am. Suors 145, 418 DWIG C (1849). Zatsch ſ rat Med. 7, 189 L, F (1912) Amer 1 Anat 13 249 CILL, A. (1827)Arch. Anal Physiol 345 LSTEIN B B, and Broca R C (1955) Guys Hoop Rop, 104 I 107 ·108 THE ANATOMY OF CONGENITAL PULMONARY STENOSIS PEACOCK, T B (1866) Malformations of the Human Heart, 2nd ed , London PRINZMETAL, M et al (1952) The Auricular Arrhythmias, Springfield, Ili QUAIN, R (1929) Elements of Anatomy, Iith ed, Vol IV, Pt 1u, The Heart, London RODBARD, S, and SHAFFER, A (1955) Circulation, 22, 764 SELLORS, T H, and BELCHER, J R. (1950) Lancet, 2, 887 SOULIÉ, P, CHICHE, P, Voci, G, NOUAILLE, J, and PITON, A (1952) Som Hộp Paris, 28, 2II9 WALMESLEY, T (1929) Quain's Elements of Anatomy, IIth ed, Vol IV, Pt ill, The Heart, London WATERSTON, D (1918) Trans roy Soc Edinb , 52, 257 ·INDEX 95 70, 86 Bidirectional shunts, 103 Angiocardiography In infundibular Blood pressure, post-operative fall in steporis, 43-4 66 72 combined with valvur rise in, 96-7 menous, 69 Bulbar ridges, II in verar stenosis, 37 76, 78 septum distal, 10, 11 selective, in valvur stenosis 81 proximal, ir valves, 3 Aorta and pulmonary artery both ensing from right ventricle 37 86–7 Bulboventricular groove 3, 8 dextropored 23, 25, 71 8667 spur 3 4 over riding in Follot's tetre disappearance of 8,13 logy SI 70-1 86-7 Bulbin arteriosus (see Bulbus cordis) dilated, in Fullot's tetrilogy, 71 cordis, 2-3 formation of 8 10-II distal limits of 21-2 endocardial cushions in 10 right phylogenetic presence of 7 Aortie reptilian, 36, 16, 86 fusion of into ventricle 2-3, Aortic ring future of sepaal defect to, 8 12-14 22 maldevelopment of us ause valve, counpetence of 99-110 of Fallot's tetralogy 69 90 of fusion of cuspi, damage to septal cusp of in 31 punch resection of crista, of stenosis 89 91 Aortopulmonary keptum 10 of fisba 3 99 Arterial root structure of 20-2 49 zone derivative of, 21 Atrial Keptum, pulmonary vilver steposis with, 26 Atrioventricular bundle, 9 16 с damage to m punch resec Caldfation endocardial 59 tion of crusta, 91 Cardiac catheteriation in infundibular relation to septal defect, 70-I stenosis 45 76 84, 102-4 onfice, right, formation of 8 II combined with - rloge reladon of septal defect to valvur itenosis, 69 70 revealing changes in muscle Atitum and opendage in pulmonary tonus, 102 alya fenols, 41 Carum arteriosum, 7 primitive, 2,8 Yerlosum, 6 Auriculoteatricular bundle (sce Atrio 'Conus area 20 veotricular bundle) prominent 72 Arterios UL, 320 Crinta supraventricularis 7 14 15 22 B fibrosis involving 59 Bicunpid niive In Fillot's tetralogy, 56 hypertrophy of, 34 109 ·IIO INDEX Crista supraventricularis, in Fallot's tetralogy, 52-3, 59, 61, 63 in infundibular stenosis 42 nomenclature of, 18 punch resection of, 91, 104-5 Cyanosis, correction of, 92 in Fallot's tetralogy, 101-2 Fallot's tetralogy, with combined yalvar and infundibular stenosis, 27, 53, 55, 57-8, 62, 69, 76, 81, 90 with infundibular stenosis, 26, 52-3, 55, 58-69, 72-6 with septal defect, 27, 53, 68, 70-1 with subdivision of right ventricle, 52 with valvar stenosis, 26, 52, 54-8, 90 infundibulum in, D Ductus arteriosus, persistent, in tricuspid atresia, 50 E Electromanometric measurements, 28 readings at operation, 76, 84 in infundibular stenosis, 45, 57, 76 combined with valvar stenosis, 57-8, 69, 76 in valvar stenosis, 32-4 Endocardial fibroelastosis, 32, 59, 63 Endocarditis, foetal', causing fusion of cusps, 31 Éperon de Wolff, 20 32 radiological diaga nosis of, 78, 81 trilogy (sce Pulmonary valvar stenosis) Fibroelastosis, endocardial, 32, 59, 63 Fishes, bulbus cordis in, 3, 22, 98-9 'Fleshy pons', 20 'Foetal endocarditis' causing fusion of cusps, 31 Foramen ovale, persistent, in pulmonary valvar stenosis, 9, 41, 92 in tricuspid atresia, 50 G F Graham Steell bruit, 106 Fallot's tetralogy, 26–7, 51-71 'Ground-glassing' of endocardium, 59 cardiac catheterisation in 102-3 cyanosis and unconscious- H ness in, IOI-2 Heart, anatomy of, nomenclaturc, 3, external appearance of heart 18, 20 in, 36 bifid apex to, 9 operative relief of stenosis in, developing human, 8-14 84-5, 90, 92-7 development of, after opcration, by punch 91-2 resection, 91, 103-4 embryology of, 1-7, 8-14 hypertenexamination of living, 27-8, 51-2 sion following, 97 external appearance in valvar regurgitastenosis, 36 tion following, 106 of fish, 3 over-riding of aorta and, primitive tubular, 2,8 86-7 reptilian, 3 recognition and differential Hunter, William, 23 diagnosis of type and level Hypertension, post-operative systemic, of obstruction in, 72-85 95-7 valvotomy for, infundibular Hypoplasia of infundibulum, 56, 58, stenosis after, 104 61-2, 90 ·INDEX III 1 Infundibular chamber, 65 90 opention la proience of 92 106 with low stenous, 66 72 84 muscle sphincterie uction of, 104-5 obstruction conular S1, 59, 63 65 89 by hypertrophied muscle, 34-6 diaphragmatic, SI 59 63 65 72, 76 89 muscular or tububar, 51-2, 62, 76 rezection 45 66, 69, 90, 95 IOS regurgitation following 106 stenosis, 26, 52-3 55 58-61 cardiac catheterisation in 45 76, 84, 102-4 cusation of 89 combined with valvar sten osis, 27 31-6, 53 55 62 69 81, 89 diagnosis of 57-8, 76 complicating tricuspid atrenia so functiom 89 high 52, 58 63 71, 90 radiographic Appar ance of 78-81 recognition of, at operation, 84 hypoplastic, 56 58 61-2 90 Intermediate 52 58 65-6 Infundibulum 15-16 22 arrangement of muscle fibres of 16-17 formation of 2 12-13 89, 98 function of, 99-101 hypoplasia of 56 58, 61-3 In pulmonary stenosis 101-4 valvur, 31-3 maldevelopment of in Fallot's tetralogy, 52-3, 58-61 muscle tonus variations in Ior-2 muscular contraction und rclare tion of 101 nomenclature of, 20 post stenotic dllatation of, 59 61 65-6 relationship of atrioventricular bundle to 9 seml vettigal, 27 surgical incision into 17-18 systolic contraction of stenosed 61 thinning of outer wall of 61 65-6 Interatrial communication pulmonary yalvar stenosis with 26 Interventricular foramen relationship with atrioventricular bundle 9 K Keith Sir Arthur zal 2 9 13-14 42 L shunt Left to-night 93-4 post-operative low 52 58 66-9 with large chamber 66 72 841 90 obliquity of septum la 68 purt 42 opertve relief of 90-2 Tesection of punch, 45 66, 69 91 104-5 secoadary after pulmomry palvotomy 32-5 104-5 with cominon ventricle, 88 with de troposition of orth, 87 with Dormal Horuc root 26, 42-6 M Mitnl valve, septal defect atending beneath 70 Moderator band, 15-16 Muscle comprarat de la valuula in ausprdale 20 Muscular hypertrophy compliating nin stenosis, 34-6 Myocardium retrogradon of 10 Over riding of sorte si 70–1 86-7 ·II2 INDEX Pulmonary stenosis, causauon of, summary, 89-90 comparative anatomy of, I diagnosis of type of, 27 embryology of, 1 infundibulum in, 101-4 operative relief of, 84-5, 90-7 age for, 91-2 regurgitation following, 106 two-stage, 92 pure (see Valvar stenosis with normal aortic root) varieties of, 26-8 with common ventricic, 87-8 with transposition of great vessels, 87 valvar (see Valvar) valve, bicuspid, 56 fusion of cusps of, 29-31, 56 regurgitation, 99-101, 105-6 valves, formation of, 21-2, 89 valvotomy (see Valvotomy) P Palpation in diagnosis of valvar and infundibular stenosis, 83-5 Papıllary muscle, anterior, 16 Pars membranacea septi, 12 Peacock, Thomas, 23-5, 42 Post-stenotic dilatation of infundibulum, 59, 61, 65, 90 of pulmonary artery, 36-41 in infundibular stenosis, 59, 63 radiological diagnosis of, 76 Pregnancy, pulmonary diastolic murmur in, after infundibular resection, 106 Pulmonary artery and aorta arising from right ventricle, 27, 86-7 development after operation, 92 displaced by hypertrophied right ventricle, 36 formation of, 8, 10-11, 13, 22 effect of dextroposed aorta on, 25 post-stenotic dilatation of, 36-41, 56 in Fallot's tetralogy, 59, 63 pressure, post-operative, 93-4 raised, 105-6 secondary stenosis of, after valvotomy, 32, 41 small, in Fallot's tetralogy, 56–7, 62-3, 70 transition to arterial root from, 21 atresia, 26-7, 47-9, 52, 91 arterial, 22, 26, 47-8 causation of, 89 valvar, 26, 48-9 causation of, 89 with tricuspid atresia, 50 canal, 20 hypertension, 106 outflow hypoplasia, 91 mechanism controlling, 98- 106 sinuses, 21 stenosis, causal relationship of, and septal dcfcct, 23-5 Q Quain's Anatomy, 3, 20-1, I0I R Radiology in diagnosis of valvar sten- OSIS, 37-41 in Fallot's tetralogy, 58, 66, 72-83 Reptile, heart of, 3, 14, 87 Right-to-left shunt, correction of, 92-7 S Semilunar valves, formation of, 10, 21 Septal defect, closure of, 70 aftcr rclief of stenosis, 92-5 in Fallot's tetralogy, 27, 51, 53, 68, 70-1, 93 in tricuspid atresia, 50 significance of, rclativc, 23 with aorta and pulmonary artcry arising from right ventricle, 86-7 with infundibular stenosis, 90 with valvar sicnosis, 41 Septum intcrmcdium, II ·INDEX 113 Septum fupernumerary , 42 Valvar stenosio radiologial diagnosis Sunus yanonus, 2 in, 76-81 ventricular 15 22 recognition of at operation Shauses of Valsaly (see Valsalva, 83-4 oxy of) with closed anal septum Spru intervalvulana 21 26, 41 Spinal ridges 10 with common ventricle 88 Spitxers theory of transposition of with datroposition of norta great vessels 7 87 Subcortic stenou congenital 12 with interatrial communia 'Supernumerary sectum 42 tlon 26 41 with normal sortic root 26, T 29-41, 76 causation of Trubecular muscle 16 88 Transposition of toru 86-7 operative of - of gratt vessels, 7, 27 Lief of, 90-92 104 with pulmonary ten with osis, 87 persistent fornen ovale 41 92 Tricuspid atresia 26 49-50, 91 Valvotomy 90 94-5 valve, damage to, la resection of blind transventricular 36 Infundibular stenosis, 45 infundibular stenosis after, 32-6, mechanism 16 septal defect covered by 70 104-5 Trilogy of Fullor (s* Valmar stenosis) muscular hypertrophy and 35-6 Truncus arteriosus, 2-3 open arterial 36 divinon of 8, 10 Ventrick, common with pulmonary function of with bulbus 22 stenow, 27, 87-8 Turtle, heart of 3 14 left displaced by hypertrophled right ventncle 36 fusion of part of bulbus into V 12 Valselva sinures of 21 of turtle 3 6 14 oblitention of 37 56 night Anatomy of normal 15-22 palpation of 84 corta and pulmonary artery Valver atre, SS 57 both visiog from 37 86-7 with common ventricle, 88 atrala of 49 tenom combined with infundi concalcd beneath sternum bular stenosis (see wonder Infun 36 ditulu) fusion of bulbu cordis in embryologlal planation 2-3 8 12-14 of 22, 89 of Infior portion of exterior appearance of hart with left 27 in 36 hypertrophy of 34-6 in Fallot's tetralogy 26 4-8 in Fullots tetralogy globular 56, 81 51-2 palpation of, In volvur stenosis 31-6 83-4 muscular constriction in 14 radiology in diag 22 DAL, 78 nomenclature of 18 obstruction in 29-31 outfon control pulmonary artery in 36-41 mechanisms in 98-106 Pure (se Valur terrie tirtim of artenl root of trict of

·114
INDEX
Ventricle right, subdivision of (see Ventricular septal defect (sec Scptal
Infundibular stenosis with normal
defect)
aortic root)
septum, absence of, 87-8
Ventricles, formation of, 8-9
closure of, 8, 11, 22, 31
musculature of, 13-14
incomplete, 23, 25
unevenness of margin of, 21
development of, 9
of primitive heart, 2, 8
Venturi effect causing low diastolic
Ventricular foramen, closure of, 13
pressure, 104