Single Coronary Artery, with Anomalous Origin of the Left Anterior Descending Artery from the Right Coronary Artery, and Anomal

The normal coronary circulation encompasses a wide spectrum of normal variants, which are often detected as incidental findings during coronary angiography. A single coronary artery ostium is a rare finding. Shirani and Roberts identified 97 patients with this anomaly, only four of whom had a single coronary artery emerging from the right coronary sinus and supplying the entire myocardium.¹ We describe a patient with a single coronary ostium arising from the right coronary Sinus of Valsalva, with the left anterior descending artery (LAD) originating from the proximal portion of a superdominant right coronary artery (RCA), and an absent left circumflex (CX) artery. Case Report. A 58-year-old-male patient with hypertension and dyslipidemia presented with an atypical chest pain of one year’s duration. Physical examination and baseline electrocardiogram were normal. An exercise stress Tl201 single photon emission computed tomography (SPECT) revealed mild reversible filling defects in the inferobasal and posterobasal segments of the left ventricle. An echocardiogram revealed normal segmental and global left ventricular systolic function. Coronary angiography showed a single, large coronary artery originating in the right coronary sinus of Valsalva (Figure 1). After traversing within the crux, the artery ascends along the AV groove and perfuses the posterolateral and lateral wall of the left ventricle. The LAD arises from the proximal portion of the RCA, immediately after the origin (Figures 2 and 3). An anomalous right superior septal artey originats in the ostial area of the RCA, and supplies the proximal septum (Figure 3). Discussion. An anomalous origin of a left main coronary artery (LMCA) from the right sinus of Valsalva has been previously described and is considered a subtype of a single coronary artery. This is a rare anomaly, comprising approximately 3% of all coronary artery anomalies.² In previously described cases, the LMCA originated either from a separate ostium or from the initial portion of the RCA.³ In the case we describe, the RCA has a normal origin and passes within the right AV groove before continuing past the crux of the heart to the left atrioventricular groove. Since it supplies the territories typically supported by the posterolateral branches, posterior descending artery, and circumflex marginal coronary artery, it can be considered a superdominant RCA. The artery was free of atherosclerotic disease. Another unique point is the course of the LAD that originates from the proximal stem of the RCA. Several anatomical subtypes exist, and are classified according to the relationship of the anomalous artery to the aorta and pulmonary artery. Thus, the position of the anomalous artery can be anterior, septal, or posterior to the aorta and pulmonary artery. These anatomical subtypes are usually benign and asymptomatic,⁴ although an unusual variant exists in which the anomalous artery passes between the aorta and pulmonary artery, leading to a potentially life threatening compromise in blood flow as a result of pressure by the great arteries.⁵ In our case, the course of the LAD is posterior to the aorta, and has a caudal-posterior loop. To our knowledge, the combination of a superdominant RCA with an absent CX, an LAD that originates from the proximal stem of the RCA, and an anomalous right superior septal artery has not been previously reported.