Congenital anomalies of the coronary arteries are present in 0.2-1.4% of the general population.  Double right coronary artery (RCA) is a very rare coronary artery anomaly with an incidence of 0.01%.  Different authors have used different terminologies for the definition of double RCA like dual RCA, split RCA, duplicated RCA, and other terminologies. Nair et al.  suggested in conventional coronary angiography that both RCA vessels run parallel in the right atrioventricular groove and both cross the crux. Kunimasa et al.  Sato et al.  proposed that double RCA should be defined when both supply the blood to the inferior left ventricular (LV) myocardium; thus, both RCAs should course downwardly to reach the interventricular sulcus whether or not they cross the crux. Lemburg et al.  suggested that adjacent but separate ostia of two RCA vessels with almost similar diameters indicate the presence of true double RCA. Misuraca and Balbarini  described a right coronary system formed of two distinct branches running very closely together in the atrioventricular groove. The two branches are of a similar caliber and can originate from a single proximal trunk or arise from distinct orifices in the right sinus of Valsalva. The double coronary artery is considered hemodynamically insignificant. It is not immune to atherosclerosis. Because of duplication, it provides better collateral support in case of left coronary atresia or total occlusion.
A 62-year-old man underwent cardiac evaluation for resection of the upper lobe of left lung for adenocarcinoma 6 months back. He is a known smoker, hypertensive, and diabetes on medication. He had New York Heart Association (NYHA) II Shortness of breath (SOB). Twelve-lead electrocardiogram was normal. Echocardiography revealed structurally normal heart with a normal LV function. Dobutamine stress myocardial perfusion was negative. During the whole body computed tomography (CT)-positron emission tomography for evaluation of distant metastasis, CT coronary angiogram had mentioned normal and single RCA, complete occlusion (13 cm) of the left anterior descending (LAD) after D1, and normal nondominant circumflex. He underwent uneventful lobectomy with high-risk consent. He recently developed angina of exertion 3 months back. We proceeded with angioplasty of LAD using the right radial approach. A 6Fr, 3.5" EBU guide was used in antegrade approach. An Optitorque TIG 5Fr diagnostic catheter was used for demonstration of retrograde filling of LAD during angioplasty via left radial access. Retrograde filling of LAD was obvious from RCA [Figure 1]. The RCA angiogram was interesting. Every attempt to hook RCA was a selective shot and deep hook. There was a significant damp of blood pressure every time when we tried to hook RCA and with slow counter clockwise pull up to right coronary sinus, a large posterior RCA was filling faintly [Figure 1] and Video 1]. Injecting contrast dye into the posterior RCA [Figure 2] resulted in selective opacification of posterior RCA arising from a separate ostium in the right coronary sinus and coursing down toward the right atrioventricular groove with arborization as a posterior descending artery and posterior LV branch. The retrograde filling of LAD from the large and posterior was not significant. Both the RCAs were not suitable for retrograde angioplasty because the posterior one had no significant collateral to LAD and anterior RCA was too small in caliber to be used for regrade angioplasty of LAD. We could not succeed in performing angioplasty using antegrade approach. This patient was sent for elective coronary artery bypass graft. Sometimes, it is necessary to investigate in detail to find the missing double RCA in the slightest of suspicion because of selective hooking spots both the RCAs, one who hides (not seen) and the other who seeks (nonselective hook partially fills the other).
Figure 1: Selective coronary angiogram of the small and anterior right coronary artery (A) showed Rentrop's Grade III collaterals to the occluded left anterior descending (D) in the right anterior oblique view. B and C are posterior left ventricular branch and PAD, respectively
Figure 2: Right coronary angiogram showed both the right coronary arteries in anterior (A) and posterior (B) relation for retrograde filling of left anterior descending coronary artery. (C) Optitorque diagnostic catheter in the right coronary sinus. (D) 6Fr EBU guide HAS hooked left anterior descending. Guidewire (E) in the progress through total occlusion in RAO (25°) and cranial (31°) view
Harikrishnan S, Jacob SP, Tharakan J, Titus T, Kumar VK, Bhat A, et al. Congenital coronary anomalies of origin and distribution in adults: A coronary arteriographic study. Indian Heart J 2002;54:271-5.
Kunimasa T, Sato Y, Ichikawa M, Ito S, Takagi T, Lee T, et al. MDCT detection of double right coronary artery arising from a single ostium in the right sinus of Valsalva: Report of 2 cases. Int J Cardiol 2007;115:239-41. [PUBMED]