Origin of anterior descending coronary artery from right aortic sinus. Intramyocardial tunneling to left side of heart.

We report a rare case of a coronary anomaly. All of the coronary arteries originated from a single ostium located in the right coronary cusp. The single coronary artery had a main branch corresponding to the usually dominant right coronary artery. The left anterior descending coronary artery arose from the right coronary artery and coursed intramyocardially within the right ventricular outflow tract to the anterior interventricular sulcus. The absence of evidence of myocardial ischemia in our patient, both clinically and at autopsy, and in three cases reported previously, suggests that the condition reported here was an unlikely cause of myocardial ischemia.