Truncus arteriosus (TA) is a rare congenital cardiovascular anomaly characterized by a single arterial trunk arising from the heart by means of a single semilunar valve (<I>i.e.</I> truncal valve). Pulmonary arteries originate from the common arterial trunk distal to the coronary arteries and proximal to the first brachiocephalic branch of the aortic arch. TA typically overrides a large outlet ventricular septal defect (VSD). The intracardiac anatomy usually displays situs solitus and atrioventricular (AV) concordance.

Pattern of blood flow in the heart that deviates from the normal circuit of the circulatory system from the right side of the heart to the left.