Coronary artery to pulmonary artery fistulas.

Twelve patients with a total of 14 coronary artery to pulmonary artery fistulas were discovered at the time of diagnostic coronary angiography. Six patients had severe coronary artery disease, five patients had normal coronary arteriography, one patient had insignificant coronary artery disease, and one patient had rheumatic heart disease. Only two patients had characteristic continuous murmurs; one patient had a normal coronary angiogram, and the second patient had severe coronary artery disease. Ten fistulas originated from the left anterior descending artery, three from the right coronary artery, and one from the left circumflex artery. The fistulas were either composed of one large (five fistulas) or one or more small channels (seven fistulas) or poorly defined plexiform channels (two fistulas). Hydrogen studies performed in two patients were negative and dye dilution curves performed in all patients were normal. In only four out of the six patients with severe coronary artery disease, the fistulas originated from a diseased vessel and in each case the origin was proximal to the narrowing. The pathogenesis and functional role of these fistulas is largely unknown.