P. Syamasundar Rao, MD
Introduction
When the author began his career in the mid-1960s, the field of Pediatric Cardiology was in early development. He has had the opportunity to witness the field’s step-wise evolution and has documented it in a book titled "How Pediatric Cardiology Has Evolved Over the Last 50 Years".[1] The purpose of the book was to bring together advances in Pediatric Cardiology on the management of congenital heart defects (CHDs), with particular attention to the author’s contributions. At first, the author’s journey was introduced when he bestowed considerable attention on the development of new knowledge and the training and teaching of physicians around the world while providing care for patients with heart disease over a 50-year period. This appraisal focused particular attention on his scientific contributions to the literature. These include the spontaneous closure of physiologically advantageous Ventricular Septal Defects (VSDs); various issues related to a relatively rare congenital heart defect – namely, tricuspid atresia; and transcatheter, interventional pediatric cardiac procedures.
FIGURE 1 A) Line drawing illustrating atrio-pulmonary type of Fontan for patients with tricuspid atresia with transposition of the great arteries. The left ventricular (LV) blood flows via the ventricular septal defect (VSD) and right ventricle (RV) into the aorta (Ao). B) If the VSD is small and restrictive, causing “subaortic” obstruction, this obstruction may be bypassed by connecting the proximal stump of the divided pulmonary artery (PA) to the Ao directly or via a non-valved conduit. C) An alternate approach is to connect the LV apex to the descending aorta (DAo). Atrial Septal Defect (ASD); Right Atrium (RA). Reproduced from Rao, PS, Br Heart J 1977; 39:276-88 and Rao PS, Ann Thorac Surg 1983; 35:121-31.
Physiologically Advantageous VSDs
When a VSD is a component of a complex heart defect, an open defect is critical in maintaining suitable intra-cardiac shunt; such a defect has been named physiologically advantageous VSD. While spontaneous closure of isolated VSDs was well documented in the 1960s and 1970s, closure of physiologically advantageous VSDs has not been a focus of prior studies. The initial observation of closure of such VSDs in patients with tricuspid atresia and double outlet right ventricle had prompted focusing on this issue. In addition to tricuspid atresia and double outlet right ventricle, such VSD closures have been documented in Tetralogy of Fallot, pulmonary atresia with VSD and Transposition of the Great Arteries with intact atrial septum. This concept may even be extended to closure of bulboventricular foramen in patients with double inlet left ventricle with ventriculo-arterial discordance. Extensive investigation of this issue in children with tricuspid atresia lead to the documentation of functional, partial and complete VSD closures. These observations have suggested that spontaneous closure of these VSDs occurs as often as in isolated VSDs and that the mechanisms of closure are similar to those seen in isolated VSDs. The closure may occur in utero, early in infancy, childhood and continues through adulthood. There is an immense natural tendency for spontaneous closure of these VSDs. In patients with tricuspid atresia and normally related great arteries, such closures will result in pulmonary oligemia requiring surgical palliation earlier than is otherwise necessary; while in patients with tricuspid atresia and transposed great arteries, such closures produce left ventricular outflow tract obstruction, requiring bypass of the VSD and the right ventricle by a pulmonary artery-to-ascending aorta anastomosis (Damus-Kaye-Stansel) or by a left ventricle-to-descending aorta conduit (Figure 1).
To read the full article, please go to the December 2020 Issue of CCT.