Common arterial trunk with intact septum and hypoplastic right ventricle: An uncommon embryological entity.

Embryologically, the common arterial trunk (CAT) is due to the failure of septation by the major outflow cushions. This invariably leads to the presence of an associated large juxta-arterial ventricular septal defect. Overriding of the ventricular septum leads to its biventricular origin in more than 2/3 of cases.