A rare, congenital anomaly of the great arteries characterized by an extrapericardial vessel arising from the ascending aorta proximal to the brachiocephalic artery and terminating either in the dorsal aorta or in pulmonary arteries via a persistently patent arterial duct. The resulting connection is a systemic-to-systemic or systemic-to-pulmonary. Clinical manifestation include exercise intolerance, reduced femoral pulses, cyanosis with or without pulmonary hypertension and heart failure. Other congenital cardiovascular anomalies are often present and influence the clinical presentation.

In utero, the ductus arteriosus (DA) serves to divert ventricular output away from the lungs and toward the placenta by connecting the main pulmonary artery to the descending aorta. A patent ductus arteriosus (PDA) in the first 3 days of life is a physiologic shunt in healthy term and preterm newborn infants, and normally is substantially closed within about 24 hours after bith and completely closed after about three weeks. Failure of physiologcal closure is referred to a persistent or patent ductus arteriosus (PDA). Depending on the degree of left-to-right shunting, PDA can have clinical consequences.