Section 2 -

Maude Abbott and the Congenitally Malformed Heart Robert H. Anderson UCL Institute of Child Health London , United Kingdom

Introduction In the frontispiece to her "Atlas of Congenital Cardiac Disease" [1], Maude Abbott pictures the five "great scientists who have made fundamental contributions to our knowledge of congenital cardiac disease". She chose a Frenchman, Jean-Baptiste de Senac, an Italian, Giovanni Baptista Morgagni, an Austrian, the Baron von Rokitansky, and two physicians and scientists from the United Kingdom, Thomas Bevill Peacock and Arthur Keith. One cannot quarrel with her choice. There can be no question, however, but that Abbott's own contributions took our understanding of the congenitally malformed heart to new heights. The contributions of her great scientists were important, and Rokitansky's own Atlas [2] illustrates many, if not most, of the malformations we recognise today, establishing for example the existence of congenitally corrected transposition (Fig. 1). Keith also made significant advances, not only clarifying the disposition of the atrioventricular conduction axis [3], and discovering the sinus node [4], but also discussing the morphogenesis of malformations involving the ventricular outflow tracts [5]. It was Abbott, however, who first gathered together and synthesised the existing descriptions of congenital cardiac malformations, which still tended to appear as isolated reports during her long career. Most importantly, she then grouped them together in clinically meaningful fashion. We continue to describe the malformations in the fashion she suggested, dividing them into acyanotic and cyanotic lesions, and further dividing the cyanotic group into those with late reversal of an arterio-venous shunt, as opposed to those with a permanent right-to-left shunt, or retardation of flow. We can also continue to learn from her Atlas, which contains an analysis of 1,000 cases, combining the autopsy and clinical findings in a table with 24 sub-sections, a format which could serve perfectly well for current listings. In her introduction, Abbott states "the Atlas here published is merely preliminary to a larger volume of congenital heart disease which the author has under preparation". As far as I am aware, this textbook never materialised, despite the fact that the Atlas was published in 1936, and Abbott lived on until 1940. Had the textbook appeared as she promised, our appreciation of the many variations in congenital cardiac disease might have been further enhanced. As it is, it was entirely appropriate that she should have entered the pantheon of giants in their field included in the mural of Diego Rivera that is housed in the Institute of Cardiology in Mexico City (Fig. 2). Developmental Considerations Abbott rightly states that "An understanding of the elementary facts of human and comparative embryology is essential to an intelligent grasp of the ontogenetic problems of congenital cardiac disease" [1]. Her emphasis on the reptilian heart is also justified, albeit that she followed the concept in vogue at that time, namely that hearts with an aorta arising from the morphologically right ventricle, such as transposition, could be explained on the basis of persistence of the right ventricular aorta to be found in animals such as turtles, crocodiles, and alligators (Fig. 3). We now know that this concept, despite the plausible suggestions made by Abbott [1], has no basis in either anatomic or developmental fact. There is much to be learned, nonetheless, from these fascinating reptilian hearts, not least the four-chambered crocodilian heart, with its foramen of Pannizza and truly septated outflow tract (Fig. 4). Certainly there is much to be learned from the development of these hearts. The avian heart, for example, more closely related to the reptiles than to the mammals, still retains three cushions within its developing outflow tract, albeit that eventually it becomes separated into two rather than three arterial channels [6]. Congenitally Malformed Hearts In her formidable table, Abbott provides clinical and pathological details concerning virtually all the malformations we recognise today. Constraints of time will prevent me from listing all the gems still to be gleaned from her writings and drawings. Instead, I will select some of the most appropriate to modern day paediatric cardiology, while also highlighting some features of more historical interest. Malformations of the aortic arch Twice in the Atlas Abbott illustrates what she describes as a "long ligamentum arteriosum". She illustrates the structure as extending from the left pulmonary artery to the descending aorta (Fig. 5). Her explanation for this lesion is unlikely to be correct, since the left-sided arterial duct, when existing with a right-sided aortic arch, passes from the left-sided brachiocephalic artery to the left pulmonary artery. Thus, if such a cord existed in this specimen, from the McGill museum, then we know from the studies of Edwards and his colleagues [7] that it would represent an atretic left arch, with interruption of the arterial ligament. Intriguingly, Abbott also illustrates a specimen with such an atretic component of the left arch (Fig. 6). Her explanation for the long arterial ligament, nonetheless, seems most unlikely, but if the specimen still exists, it is worthy of further study. Aortic Coarctation The section devoted to coarctation is comprehensive, and all of the findings are as relevant today as when first described. Her reproduction of the picture of Meckel is particularly appropriate. She also shows an exquisite chest radiograph provided by "Douglas Wilkinson of Birmingham , England ." Discovering this part of the Atlas had direct relevance to me, since Dr Wilkinson was the father of James Wilkinson, who collaborated with me in producing so many of our own investigations of development and structure of the congenitally malformed heart [8, 9, 10]. Jim still has a copy of a letter from Maude, arranging a visit to Birmingham in 1932 (Fig. 7). Jim is currently the Senior Paediatric Cardiologist at Royal Children's Hospital, Melbourne , and has himself made many significant contributions to our understanding of the congenitally malformed heart [11]. The Arterial Valves The coverage of abnormalities of the aortic valve is just as thorough as that for aortic coarctation. Abbott stresses the semilunar attachments of the leaflets, and illustrates the important interleaflet triangles. These structures tended to be forgotten in the decades that followed [12], but they represent a feature which still demands attention, with uncertainty remaining as to the precise definition of the valvar "annulus" [13]. The Arterial Duct The page devoted to the arterial duct is particularly beautiful, with some excellent diagrams drawn by her colleague, Dr Segall, to show the location of the murmur, and how its character changes with posture (Fig. 8). Abbott points out that the allegedly typical "machinery" murmur [14] is heard in only one-third of cases, basing this analysis on details gathered together from 92 previously published cases. Deficient Atrial Septation The writing of this section would give great problems in terms of current political correctness, since she refers to "Mongolian idiocy", but Abbott rightly highlights the important morphological differences between defects within the oval fossa, and those involving deficient atrioventricular septation, albeit that like so many authors, she describes "cleavage and insufficiency of the anterior mitral segment". From her illustrations, nonetheless, we can distinguish the difference between the normal mitral valve seen in the setting of the deficiency within the oval fossa, and the trifoliate valve in the setting of the common atrioventricular junction [15]. Significantly, she does not discuss either the sinus venosus defect, nor the defect found at the mouth of the coronary sinus. Deficient Ventricular Septation Considering that defects of the ventricular septum are the commonest type of congenital cardiac malformation, her coverage of this lesion is perhaps unduly short. And she describes only defects at the base, which we would now call perimembranous, and "other or multiple defects". She does, however, emphasise the importance of bacterial endocarditis, also illustrating this complication in the setting of a ruptured aneurysm of the aortic sinus of Valsalva. In subsequent sections, she illustrates and comments on deficient ventricular septation in combination with other lesions, such as tetralogy of Fallot and common arterial trunk. She also indicates the origin of "Eisenmenger's complex" – the name we now use to describe overriding of the aorta in the absence of subpulmonary stenosis [16]. As Abbott explains, the term was coined by her "in default of a better". Present day confusion arose only when Wood [17] subsequently described the "Eisenmenger reaction", accounting for the shift to overt cyanosis in Abbott's grouping of "cyanosis tardive". Pulmonary Atresia with Closed Ventricular Septum Abbott shows a remarkable understanding of this lesion, along with what we now call hypoplasia of the left heart, which is way ahead of her time. She emphasises the potential inflammatory origin, or valvar endocarditis, pointing out that the lesion sets in "in later foetal life after the heart chambers are completely separated". Congenitally Corrected Transposition Although listing only 4 examples of the lesion characterised by discordant connections at both atrioventricular and ventriculo-arterial junctions, and collecting 16 examples of "partial transposition", which we now call double outlet right ventricle [18], her illustration of the lesion is exquisite, and parallels that of von Rokitansky in providing the necessary understanding of the autopsied specimen. Double Inlet Left Ventricle It is for her description of the so-called "Holmes Heart" that most of us now remember Maude Abbott, not least because the heart itself is so beautifully preserved in the McGill museum, despite having been first described by Andrew Holmes in 1824 [18]. Intriguingly, Abbott does not describe the chamber supporting the pulmonary trunk as the incomplete right ventricle, whilst one of her illustrations of the commoner variant of double inlet left ventricle with discordant ventriculo-arterial connections labels the smaller ventricular chamber as the "rudimentary left ventricle". Conclusions Although we can find fault with some of her descriptions, and not surprisingly our understanding has moved on since the appearance of her Atlas, the beginner in paediatric cardiology today could do much worse than to read thoroughly the works of Maude Abbott. She was truly the giant who provided the firm foundations of our modern-day knowledge. References Abbott ME. Atlas of Congenital Cardiac Disease. New York: The American Heart Association, 1936. von Rokitansky CF. Die Defecte der Scheidewande des Herzens. Vienna: Pathologisch-Anatomisch Wilhelm Braumuller, 1875. Keith A, Flack M. The auriculo-ventricular bundle of the human heart. Lancet 1906; 2:359-364. Keith A, Flack M. The form and nature of the muscular connections between the primary divisions of the vertebrate heart. J Anat Physiol 1907; 41:172-189. Keith A. Fate of the bulbus cordis in the human heart. Lancet 1924; 2:1267-1273. Qayyum S, Webb S, Brown NA, Anderson RH, Verbeek FJ, Richardson MK. Septation and valvar formation in the outflow tract of the embryonic chick heart. Anat Rec 2001; 264:273-283. Stewart JR, Kincaid OW, Edwards JE. An Atlas of Vascular Rings and Related Malformations of the Aortic Arch System. Springfield Ill: Charles C. Thomas 1964. Anderson RH, Wilkinson JL, Arnold R, Becker AE, Lubkiewicz K. Morphogenesis of bulboventricular malformations. II. Observations on malformed hearts. Br Heart J 1974; 36:948-970. Anderson RH, Arnold R, Wilkinson JL. The conducting system in congenitally corrected transposition. Lancet 1973; 1:1286-1288. Wilkinson JL, Arnold R, Anderson RH, Acerete F. 'Posterior' transposition reconsidered. Br Heart J 1975; 37:757-766. Wilkinson JL, Acerete F. Terminological pitfalls in congenital heart disease. Reappraisal of some confusing terms, with an account of a simplified system of basic nomenclature. Br Heart J 1973; 35:1166-1177. Anderson RH. Demystifying the anatomic arrangement of the aortic valve. Editorial Comment. Eur J Cardio-thorac Surg 2006; 29:1006-1007. Sutton JPIII, Ho SY, Anderson RH. The forgotten interleaflet triangles: A review of the surgical anatomy of the aortic valve. Ann Thorac Surg 1995;59:419-427. Tynan M. The murmur of the persistently patent arterial duct, or "The Colonel is going to a dance". Cardiol Young 2003; 13:559-562. Anderson RH, Ho SY, Falcao S, Daliento L, Rigby ML. The diagnostic features of atrioventricular septal defect with common atrioventricular junction. Cardiol Young 1998; 8:33-49. Oppenheimer-Dekker A, Gittenberger-de Groot AC, Bartelings MM, Wenink ACG, Moene RJ, Van der Harten JJ. Abnormal architecture of the ventricles in hearts with an overriding aortic valve and a perimembranous ventricular septal defect ("Eisenmenger VSD"). Int J Cardiol 1985; 9:341-355. Wood P. The Eisenmenger syndrome or pulmonary hypertension with reversed central shunt. Br Med J 1958; 2:701-709. Wilkinson JL. Double outlet ventricle. In: Anderson RH, Baker EJ, Macartney FJ, Rigby ML, Shinebourne EA, Tynan M, (eds). Paediatric Cardiology Second Edition. Edinburgh: Churchill Livingstone, 2002: 1353-1382. Holmes AF. Case of malformation of the heart. Trans Med-Chir Soc Edinb 1824; 1:252-259.