Anomalous pulmonary origin of the left coronary artery.

Coronary Artery To the Editor: The echocardiographic images of the anomalous origin of the left coronary artery from the main pulmonary artery presented by Lin et al1 are very instructive. But I disagree with the statement the authors made in the legend of their Figure 3 that “Turbulent flow from the main pulmonary artery through the orifice to the left coronary artery is evident.” In anomalous origin of the left coronary artery from the main pulmonary artery, because pulmonary artery pressure is lower than the aortic pressure, blood flows from the aorta to the right coronary artery, then through collateral channels to the left coronary artery and finally to the main pulmonary artery. As a matter of fact, the anomalous left coronary artery behaves as a fistulous communication between the aorta and the main pulmonary artery. That is the reason why both the normally arising right coronary artery and the anomalous left coronary artery are dilated as shown. Therefore, the flow through the anomalous pulmonary origin of the left coronary artery is into, not from, the main pulmonary artery.