Bilateral congenital coronary artery--pulmonary artery fistulae: report of two unusual cases.

Congenital coronary arteriovenous fistulae involving both coronary arteries are rare. Those terminating in a right heart chamber or the pulmonary artery usually mimic a patent ductus arteriosus because of the presence of a continuous murmur. Since the vascular resistance is much lower in the pulmonary circuit than in myocardial capillaries, a large percentage of coronary blood flow may be directed through the fistula. Such a "steal" can cause myocardial ischemia distal to the origin of the fistula. Angina has been reported to occur. About 20% of coronary A-V fistulae are associated with other congenital cardiac anomalies.