Congenital anomaly of the true double-lumen right coronary artery: An extremely rare case

Summary

Double right coronary artery is a rare anomaly which is mostly identified by two separate pathways with a common ostium (one-two way). We report herein an extremely rare case of congenital true double-lumen right coronary artery, an anomaly, where a common pathway from the ostium to the proximal segment diverged into two separate pathways from the proximal to the mid-segment and then converged into one pathway (one-two-one way).

Introduction

The incidence of coronary artery anomalies varies from 0.95 to 2.00% in the adult population undergoing coronary angiography (CAG) [1], [2], [3]. The majority of these are reported to be anomalies of origin or distribution, with the occurrence of a separate ostium of the left anterior descending artery and left circumflex artery being the most common. However, double right coronary artery (RCA) is a rare anomaly which is mostly formed by two separate pathways with a common ostium (one-two way) or a common pathway with a separate ostium (two-one way) [4], [5]. We present an extremely rare case of congenital anomaly of the true double-lumen RCA where a common ostium separated into two pathways from the proximal to the mid-segment and then became a common pathway (one-two-one way).

Case report

A 36-year-old man presented with exertional chest pain from 6 months ago. An electrocardiogram showed no ST-T abnormalities. He had no medical history of diabetes mellitus, hypertension, chest trauma, cigarette smoking, or family history of coronary artery disease. His lipid profile results were: total cholesterol, 187 mg/dL; triglycerides, 56 mg/dL; HDL cholesterol, 57 mg/dL; and LDL cholesterol, 119 mg/dL. A treadmill exercise test was performed on modified Bruce protocol, but terminated due to typical chest pain at 10 METs (15 min) without ST-T changes. The CAG showed no significant stenosis in the left coronary artery. The RCA was cannulated with 5 Fr. Judkins right diagnostic catheter. The RCA angiography demonstrated mild stenosis and suggested a double-lumen from the proximal to the mid-RCA, which originated from a common ostium (Fig. 1). Two guide wires were inserted into the two different paths to identify the true double-lumen. Two guide wires ran separate pathways at the proximal segment and then became one at the mid-segment (Fig. 2). After the CAG, the patient received medications uneventfully during a 5-year clinical follow-up. We performed a coronary computed tomography (CT) angiography for a follow-up of the RCA lesion (Fig. 3).

Figure 1.

The right coronary artery (RCA) angiography demonstrated mild stenosis and suggested a double-lumen from the proximal to the mid-RCA which developed from a common ostium. It is important to note that the true double-lumen has side branches arising from each lumen. One lumen's side branchs are shown by two dotted arrows and the other is show by a straight arrow. (A) Right anterior oblique view; (B) left anterior oblique view.

Figure 2.

Two guide wires were successfully inserted into the two different paths to identify the true double-lumen (A). The guide wires ran separate pathways at the proximal segment and then met at the mid-segment (B). The white line represents a schematic diagram of the true double-lumen.

Figure 3.

Volume-rendered images, without the myocardium, of the 64-slice computed tomography. The left coronary artery (LCA) showed no significant stenosis. The right coronary artery (RCA) appears to begin with one lumen (A of mid-inserts, arrow). It separates clearly into double-lumen (B and C of mid-inserts, double arrows), and then becomes one lumen again (D of mid-inserts, arrow).

Discussion

A double RCA is a very rare anomaly with only a few cases being reported in the past. Most previously reported cases were anomalies where a common ostium diverged into two separate pathways (one-two way). In one reported case, the separate pathways occurred due to separate ostia and then became one path at the mid-segment (two-one way) [4], [5]. This is the first case in the literature of RCA anomalies where a common ostium diverges into two separate pathways from the proximal to the mid-segment and converges back to a common pathway (one-two-one way). The present case was initially considered a spontaneous or catheter-induced dissection. However, spontaneous dissections of the coronary artery mainly occur in young women with oral contraceptives or during the peripartum period [6], [7], [8]. Catheter-induced dissections usually begin at the catheter tip. In this case, the patient had no history of spontaneous severe chest pain or blunt chest trauma. The double-lumen began at the proximal segment of the RCA, not the catheter tip or the ostium. As well, there was a noticeable gap in between the double-lumen which was very tortuous. To confirm if this case was a true double-lumen anomaly, two guide wires were inserted into the two different paths from the proximal to the mid-segment of the RCA. The guide wires ran separate pathways at the proximal segment and then converged at the mid-segment. The appearance of the patient's RCA was similar to a previously reported case that had a dissection and healing post percutaneous transluminal coronary angioplasty [9]. However, in the present case, the patient had no history of coronary intervention. Also, double-lumens were long and more importantly, had side branches arising from each of them.

The presence of the congenital true double-lumen RCA was conclusively confirmed and this was successfully managed with medical therapy.