Left main coronary artery compression by dilated main pulmonary artery in endocardial cushion defect.

A 56-year-old man was evaluated for exertional dyspnoea. Chest X-ray showed mild cardiomegaly and a dilated main pulmonary artery. On echocardiogram he was found to have ostium primum atrial septal defect with moderate tricuspid insufficiency. Cardiac catheterization revealed an oximetry step-up of 14% at low right atrium with angiogram demonstrating a cleft in the mitral valve, an elongated left ventricular outflow tract and ventricular septal defect closed by a septal aneurysm. Coronary angiogram revealed ostial compression of the left main coronary artery with the rest of the coronary artery anatomy being normal.