Defective regional myocardial development and vascularization in one variant of tricuspid atresia—clinical and necropsy findings in three cases

Abstract

SummaryFive previously reported cases have established the combination of a small right ventricle (sometimes with Uhl's anomaly), imperforate tricuspid valve with fibrotic tensor apparatus, congenital absence of the pulmonary valve, and an intact interventricular septum with muscular subaortic stenosis as a rare variant of tricuspid atresia. In this study of three new autopsy cases, we additionally identified Ebstein's malformation of the imperforate tricuspid valve, partial Uhl's anomaly, regional dysplasia of right ventricular myocardium and thinning of the interventricular septum by intramyocardial sinusoids from the right ventricle. All three new cases had epicardial anomalies of the right coronary artery—a fistula to right ventricle, ostial stenosis and proximal arterial hypoplasia. Sinusoidal connections from the right ventricle to the right coronary artery and to the sclerotic left anterior descending artery were identified in serial sections of the right ventricle and septum. Myofiber disarray, with thick walled intramyocardial arteries and sinusoids from left ventricle, involved the bulging subaortic interventricular septum. These studies are consistent with the hypothesis that defective development of the the right ventricle, along with its blood supply and associated atrioventricular and arterial valves, may underlie this unusual form of congenital heart disease.