Anomalous right coronary artery originating from the left anterior descending artery: case report and review of the literature.

The anomalous origin of the right coronary artery (RCA) as a branch of the left anterior descending (LAD) artery is a very rare variation of single coronary artery. At least 36 cases have been described previously in the literature. The vast majority of previous reports have described a single anomalous vessel with its origin after the first septal perforator of the LAD, which courses anterior to the right ventricular outflow tract to reach territory normally served by the right coronary artery. Of 35 cases in structurally normal hearts, 19 (54%) patients had >50% narrowing in one or more epicardial coronary arteries (54%), at least 14 (40%) of whom required revascularization. Thirteen cases (37%) did not have significant coronary artery disease, while the remaining 3 cases were unclear. The current report reviews previous reports of this anomaly and describes a patient with an anomalous RCA from the mid-LAD, in whom heart block, back pain and dyspnea was the initial manifestation of ischemia. On heart catheterization, there was significant coronary artery disease in the LAD proximal to the origin of the anomalous artery. The patient was successfully revascularized with a unique sequential left internal mammary artery bypass to the anomalous vessel and LAD.