A new hypothesis of the developmental origin of congenital left anterior descending coronary artery to pulmonary artery fistulas.

The embryologic origin of fistulous communications between a coronary artery and the pulmonary artery has traditionally been explained as the persistence of an immature supernumerary coronary artery with its origin in the pulmonary trunk. Although this hypothesis is consistent with the occurrence of the termination of the fistula in the posterior sinus of the pulmonary artery, it does not completely explain several morphologic and physiologic aspects. In this report, we present a case illustrating the classic anatomic features of left anterior descending artery to pulmonary artery fistulas and develop a new hypothesis of its embryologic origin and re-emergence in adults that fully explains its angiographic appearance and clinical attributes.