Severe congenital stenosis of the left coronary artery ostium and its possible pathogenesis according to current knowledge on coronary artery development.

We report a 72-year-old woman with severe congenital stenosis of the left coronary artery orifice and clinically significant atherosclerotic changes in both the right and left coronary arteries. The stenotic ostium was located at the point at which the left and posterior aortic valve leaflets joined to form the left commissure, just at the distal vertex of the left interleaflet triangle, between the left and posterior aortic sinuses. The right coronary artery was more developed in size than usual, whereas the left coronary artery consisted of a short left main coronary trunk that bifurcated into left anterior descending and left circumflex arteries. The left coronary artery system was filled retrogradely through two vessels proceeding from the right coronary artery, namely, the conal artery and a well-developed branch that ran across the interventricular septum. This abnormal arrangement of the coronary arteries showed striking functional similarities with atresia of the left main coronary artery. Current knowledge on the morphogenesis of the coronary arteries suggests that the present anomalous coronary artery pattern resulted from the penetration of the anticipated left coronary artery system into the aorta at a totally erroneus site. This hindered the normal development of the ostium, which subsisted as a punctiform, practically nonfunctional opening.