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.

A hemangioma is a benign tumor characterized by blood-filled spaces lined by benign endothelial cells. A hemangioma characterized by large endothelial spaces (caverns) is called a cavernous hemangioma (in contrast to a hemangioma with small endothelial spaces, which is called capillary hemangioma).