Anatomy of the Functionally Univentricular Heart

The world of pediatric cardiac surgery and cardiac surgery as a whole lost one of the great pioneers with the passing, at the beginning of 2018, of Francis Fontan. Hence to add to the recognition of his achievements, the European Congenital Heart Surgeons Association (ECHSA) has established a lecture to be given in his memory at their annual meetings. It was a significant honor and privilege to be invited to present the initial lecture. In this report, we describe the essence of the presentation. Many patients are now palliated by construction of the Fontan circulation. Very few of those put forward for this operative procedure have anatomically univentricular hearts. It remains frequent, nonetheless, to find accounts of many patients allegedly having "single" ventricles. We discuss the background to this illogical approach to description of hearts having one big and one small ventricle, showing that those with normal hearts have a single left ventricle, albeit co-existing with a single right ventricle. We show that analysis of the ventricular mass in tripartite fashion produces much needed clarity in the appropriate description of the ventricular mass in those increasingly submitted for construction of the Fontan circulation. We emphasize that although it was patients with univentricular atrioventricular connections who were the first to benefit from the procedure, the majority of patients now have biventricular atrioventricular connections, although the hypoplastic ventricle possesses all three of its normal components. We show that description of the ventricular arrangement as being functionally, or physiologically, univentricular provides logic in what had previously been an illogical environment.