Anomalous origin of the left coronary arterial tree through three stems--one from the pulmonary trunk.

In an 18-year-old asymptomatic male athlete, the left anterior descending coronary artery was found to arise from the pulmonary trunk. The remainder of the left coronary arterial tree arose through two stems from the aorta. Collateral retrograde filling of the left anterior descending coronary artery from the right coronary artery and the left circumflex coronary artery was demonstrated, but we found no evidence of left-to-right shunting into the pulmonary trunk. The patient has chosen conservative treatment, thus offering an unusual opportunity to follow the natural course of this lesion, which may increase understanding of its natural history.