Anomalous origin of the left circumflex coronary artery: A case report

Abstract

The anomalous origin of the left circumflex coronary artery from the right sinus of Valsalva is a relatively common anatomical variation. Difficulties may occur in the diagnostic procedure, but recognition and adequate visualization of the anomaly is essential for proper patient management, especially in patients undergoing evaluation for percutaneous coronary intervention, coronary artery surgery or prosthetic valve replacement. In the present report, a patient who had undergone percutaneous coronary intervention for a right coronary artery lesion after inferior myocardial infarction is described. The anomalous origin of the left circumflex coronary artery arising independently from the right sinus of Valsalva was previously undetected.

Coronary artery anomalies have been identified in 0.6% to 1.5% of coronary angiograms (1,2). An anomalous origin of the left circumflex coronary artery (LCX) from the proximal right coronary artery (RCA) or right sinus of Valsalva is a relatively common anatomical variation. Difficulties may occur in the diagnostic procedure (ie, the ostium of an aberrant vessel is difficult to identify), but recognition and adequate visualization of the anomaly is essential for proper patient management, especially in patients undergoing evaluation for percutaneous coronary intervention (PCI), coronary artery surgery or prosthetic valve replacement (3).

In the present report, we describe a patient who had undergone PCI for a RCA lesion after inferior myocardial infarction (MI), in whom the anomalous origin of the LCX arising independently from the right sinus of Valsalva was previously undetected.

CASE PRESENTATION

A 57-year-old male patient with hypertension, diabetes mellitus and dyslipidemia presented with exertional chest pain that had lasted for five months. He had suffered an inferior MI 28 months before evaluation. His previous coronary angiogram revealed that the left coronary artery system was normal, but the proximal RCA was totally occluded. Thus, the patient had undergone PCI to the RCA lesion just after MI. His physical examination, echocardiogram and electrocardiogram were normal, except for pathological Q waves in derivations of DIII and aVF. A coronary angiography of the left system showed a 50% stenosis of the midportion of the left anterior descending artery (LAD), while the LCX was unable to be visualized in the standard angiography views. Afterwards, the right coronary angiogram was performed and it was shown that the proximal RCA was totally occluded (restenosis). After locating the ostium of the RCA, a previously undetected anomalous but normal LCX arising independently from the right sinus of Valsalva was selectively catheterized by directing the catheter tip more posteriorly and at times more inferiorly (Figure 1). Also, during left ventriculography, in a right anterior oblique projection, the anomalous LCX was seen in profile behind the aortic root as it coursed to the left atrioventricular groove (Figure 2). The RCA lesion was not suitable for PCI, so the patient was discharged with an appropriate medical therapy.

Figure 1.

An anomalous but normal left circumflex coronary artery (LCX) arising independently from the right sinus of Valsalva is seen by coronary arteriography in a right anterior oblique projection

Figure 2.

The anomalous left circumflex coronary artery is seen in profile behind the aortic root as it courses to the left atrioventricular groove (arrow) by left ventriculogram in a right anterior oblique projection

DISCUSSION

The origin of the LCX from the right sinus of Valsalva is a well-known anatomical variation (1,2). Recognition and angiographic demonstration of the anomalous artery assumes high priority. The clinical significance of the anomaly is obvious in patients undergoing PCI or cardiac surgery (3). The first case series of PCI performed on such aberrant vessels was described in 1982 (4). A failure to recognize and properly demonstrate the anomaly can be hazardous to patient management. On the other hand, coronary anomalies are quite unusual to find during routine coronary angiography. Two angiographic signs have been previously described and have proven to be reliable in recognizing the anomalous artery before its selective demonstration (5). One sign is a profile view of the artery behind the aortic root during left ventriculography (the ‘aortic root sign’), and the other sign is a recognition of absent arterial inflow to a significant area of the posterior lateral left ventricle during selective injections of the main left coronary artery (the ‘sign of nonperfused myocardium’). Hence, in the present patient, we used these signs to show a previously undetected anomalous origin of the LCX arising independently from the right sinus of Valsalva. We suspected that the cause of the exertional chest pain of the patient was due to total occlusion of the RCA, because he had a patent LCX and a nonsevere lesion of the LAD. In addition, our patient having a closed RCA (restenosis), with inferior Q-wave MI and normal echocardiographic findings, is an unusual case in the literature.

An aberrant but normal LCX arising from the right coronary sinus (common or separate ostium with the RCA) has no clinical significance per se, and it does not predispose the LCX to a higher incidence of obstructive disease (5). The presence of obstructive disease, however, especially in a vessel of large distribution, makes it mandatory that the anomaly be recognized and angiographically demonstrated, especially in acute MI. Sometimes, in acute MI, no evidence of an occluded coronary artery can be seen during angiography. This might lead to a large spectrum of differential diagnoses to explain the acute chest pain or the electrocardiogram modification (3). The absence of an epicardial vessel or its branch, which is anatomically supposed to supply a myocardial ischemic area identified at the left ventriculography, suggests that an anatomical variation of the normal coronary tree (ie, the aberrant artery) has to be actively searched. During selective opacification of the left coronary artery, an avascular area in the posterior lateral left ventricular myocardium suggests that there is an anomalous origin of the LCX (5). Also, a consistent finding during left ventriculography in a right anterior oblique projection is a profile view of the anomalous circumflex as it courses posteriorly behind the right sinus of Valsalva (5).

CONCLUSIONS

It may be difficult to diagnose an occluded RCA by echocardiogram in a patient with normal left ventricular wall motions. Also, a high level of anticipation should be maintained during the performance of coronary arteriography, because an anomalous LCX arising independently from the right sinus of Valsalva is the most common deviation from unusual coronary artery anatomy encountered in adults.