Superdominant right coronary artery giving rise to left circumflex coronary artery as a terminal extension.

To the Editor: Coronary artery anomalies are generally discovered incidentally during coronary angiograms. The failure to visualize a coronary artery in its expected anatomic site may be misinterpreted as a total occlusion. It is essential that cardiothoracic surgeons and interventional cardiologists be familiar with abnormal coronary anatomy to perform accurate management.

A 76-year-old man with a history of exertional dyspnea and chest pain was referred to our clinic for preoperative evaluation before elective noncardiac surgery. A treadmill exercise test was planned to evaulate inducible ischemia and functional capacity, but the test was prematurely terminated at Stage 2 because of exhaustion and dyspnea. Diagnostic coronary angiography was therefore undertaken, which revealed a normal left anterior descending (LAD) artery, but the left circumflex artery (LCA) could not be visualized in its usual location. Upon selective right coronary angiography, a superdominant right coronary artery (RCA) was noted (Fig.), which crossed the crux of the heart and ascended into the atrioventricular groove, perfusing the posterolateral and lateral walls of the left ventricle and terminal branches of the RCA, feeding into LCA territory. No critical stenotic lesions were detected in either coronary artery. An aortic root arteriography was performed to see if there were any unusually located left circumflex arteries, but it verified the absence of LCA. Pharmacologic myocardial perfusion scintigraphy with dipyridamole revealed no evidence of myocardial ischemia, especially in the area supplied by the LCA.

LAD and LCA originating from separate orifices in the left sinus of Valsalva is the most common coronary anomaly, with an incidence of 0.41%. It constituted 30.4% of all coronary anomalies in the series by Yamanaka and Hobbs, which is the largest study on that area in the literature. (1) The LCA arising from the right sinus of Valsalva, the RCA, or very rarely from the pulmonary artery are other congenital anomalies involving the origin of LCA. (2,3) Absence of left circumflex is a very rare anomaly, being reported in only a few cases. (4) In most of the cases, a large, superdominant RCA crosses the crux of the heart and then ascends into the AV groove perfusing the posterolateral and lateral walls of the heart. (1) In these cases, it is more appropriate to identify LCA as a terminal extension of RCA instead of being absent. Since the coronary arteries are named according to their site of distribution (5) it is inapproprite to talk about absence of a coronary artery. True congenital absence of a coronary artery is expected to lead to hypoplasia of the dependent myocardium.

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We believe that cardiovascular surgeons and interventional cardiologists must to be familiar with abnormal coronary anatomy for accurate diagnosis and management. In such a case, a benign anomaly may be misinterpreted as a totally occluded LCA. Quick recognition of the variant anatomy by the angiographer also causes shorter procedure duration and less x-ray exposure.

Turgay Celik, MD

U. Cagdas Yuksel, MD

Atila Iyisoy, MD

Hurkan Kursaklioglu, MD

Sedat Kose, MD

Ersoy Isik, MD

Department of Cardiology

Gulhane Military Medical Academy, School of Medicine

Etlik-Ankara, Turkey

References

1. Yamanaka O, Hobbs RE. Coronary artery anomalies in 126,595 patients undergoing coronary arteriography. Cathet Cardiovasc Diagn 1990;21:28-40.

2. Page HL Jr, Engel HJ, Campbell WB, et al. Anomalous origin of the left circumflex coronary artery. Recognition, angiographic demonstration and clinical significance. Circulation 1974;50:768-773.

3. Ott DA, Cooley DA, Pinsky WW. Anomalous origin of circumflex coronary artery from right pulmonary artery: report of a rare anomaly. J Thorac Cardiovasc Surg 1978;76:190.

4. Ilia R, Jafari J, Weinstein JM, et al. Absent left circumflex coronary artery. Cathet Cardiovasc Diagn 1994;32:349-350.

5. Angelini P. Coronary Artery Anomalies. Philadelphia, Lippincott Williams & Wilkins, 1999, pp 31-34.Letters to the Editor