Use of navigator-echo-gated MRI to diagnose a coronary shunt involving an anomalous origin of the right coronary artery from the pulmonary artery.

Origin of the right coronary artery from the main pulmonary artery is an anomaly that can cause formation of a left-to-right coronary shunt, leading to myocardial ischemia and early onset of congestive heart failure. We describe a case in which magnetic resonance imaging was able to show the anomalous origin of the right coronary artery, and magnetic resonance phase velocity mapping was able to demonstrate the presence of a left-to-right shunt through the coronary artery by showing retrograde flow in the right coronary artery.