Intercoronary communication between the circumflex and right coronary arteries

A 55-year-old woman presented with exertional chest pain. Her exercise test was abnormal, and cardiac catheterization and coronary angiography showed normal left ventricular function with an 80% stenosis in the mid-left anterior descending artery. There was no angiographic evidence of coronary atherosclerosis in either the right or circumflex artery. Contrast injection into the left coronary artery suggested arte-