Echo-phonocardiographic and contrast studies in conditions associated with systemic arterial trunk overriding the ventricular septum: truncus arteriosus, tetralogy of Fallot, and pulmonary atresia with ventricular septal defect.

Echocardiography was performed in 62 patients--20 with truncus arteriosus, 14 with tetralogy of Fallot, and 28 with pulmonary atresia with ventricular septal defect. Features common in all three groups were: large single systemic arterial trunk overriding the ventricular septum, mitral-semilunar continuity, large right ventricular dimension, and normal septal motion. Indocyanine green contrast flow patterns were similar and were most helpful in detecting an associated atrial septal defect and in studying the timing and pattern of right-to-left shunting. Echo-phonocardiographic studies revealed that the ejection click coincided with the point of maximal opening of aortic or truncal valve. Left atrial dimension was measured in 55 patients and was normal or small in 41 patients and large in 14 patients. Our observations indicate that left atrial dimension provides a good index of pulmonary flow and can help differentiate those patients with increased pulmonary flow and can help differentiate those patients with increased pulmonary flow (truncus arteriosus) from those patients with reduced pulmonary flow (tetralogy of Fallot and pulmonary atresia with associated ventricular septal defect).