UNIVENTRICULAR HEART OF RIGHT VENTRICULAR TYPE WITH DOUBLE OR COMMON INLET

17 cases are described in which both atria connect directly to a chamber with right ventricular characteristics. The atria connected through separate atrioventricular valves in 6 hearts and a common valve in 11. All hearts had a posterior rudimentary chamber. The septum which separated it from the main chamber was directed to the crux of the heart. 10 hearts were from patients with atrial situs solitus and 7 from patients with atrial situs ambiguus. Arterial connections were concordant in 3 cases, had a double outlet from the main ventricular chamber in 9 and single outlet of the heart in 5. The patent artery always arose from the main chamber, with pulmonary atresia in 3 and aortic atresia in 2. This and other studies indicate that double inlet atrioventricular connection does not predict the morphology of the main chamber. Although usually associated with a main chamber of left ventricular type, it may also be associated with a main chamber having right ventricular characterisitics. Both types should be considered as univentricular hearts of left ventricular type and are a rudimentary chamber rather than a hypoplastic ventricle. In the right ventricular heart, the trabecular zone of the rudimentary chamber is of left ventricular type.