Double right coronary artery

Double right coronary artery has been described as a right coronary system formed of two distinct branches, and the two double right coronary arteries have similar diameters.Reference Misuraca and Balbarini ⁵ In some patients, a double right coronary artery can originate from a single ostium and split into two branches after a variable short distance from the proximal trunk (Fig 1a), whereas in others it originates from different ostia in the right sinus of Valsalva (Fig 1b). Nevertheless, there are no standard and authoritative definitions of a double right coronary artery until now.Reference Misuraca and Balbarini ^{5 –} Reference Chen, Chien, Chen, Lin and Lee ⁸ A comprehensive literature search was carried out through the PubMed database using the keywords “double right coronary artery”, “duplicated right coronary artery”, “dual right coronary artery”, and “split right coronary artery”. We also reviewed references from select case reports. So far, a double right coronary artery has been reported 39 times and in 46 patients;Reference Chien, Lee, Lin and Chen ⁹ among them were 37 men and nine women, with a 4:1 male predominance. The mean age at diagnosis was 54.9 ± 12.1 years. Interestingly, over half (56.5%, 26/46) the cases of this coronary anomaly were reported from Turkey. We divided the patients into two groups based on whether the double right coronary artery originated from a single ostium or from separate ostia in the right sinus of Valsalva.

Figure 1 ( a ) The right coronary angiography revealed two separate RCAs originating from a single ostium in the right sinus of Valsalva. Both RCAs gave off branches with typical courses and in parallel distribution.Reference Selcoki, Yilmaz, Er and Eryonucu ³⁹ ( b ) The posterior anterior view reveals two coronary vessels with almost similar diameters that have adjacent but separated ostia arising from the right coronary sinus.Reference Lemburg, Peters, Scheeler, Nicolas and Heyer ¹⁶ ( c ) The anterior RCA artery gave off two right ventricular branches (acute marginals) ending in the inferoapical area. The posterior RCA had no ventricular branches and gave off two large arteries distally.Reference Capunay, Carrascosa and Deviggiano ¹⁸ ( d ) The left anterior oblique view of the totally occluded proximal RCA before percutaneous coronary intervention.Reference Akcay, Koroglu, Kaya, Koleoglu and Acar ⁴⁰ ( e ) After predilatation with a sprinter balloon from panel (d), atypical double RCA appeared. (d), atypical double RCA appeared. Reproduced with permission from Selcoki et al,Reference Selcoki, Yilmaz, Er and Eryonucu ³⁹ Lemburg et al,Reference Lemburg, Peters, Scheeler, Nicolas and Heyer ¹⁶ Capunay et al,Reference Capunay, Carrascosa and Deviggiano ¹⁸ and Akcay et al.Reference Akcay, Koroglu, Kaya, Koleoglu and Acar ⁴⁰ CA = catheter angiography; LAO = left anterior oblique; RCA = right coronary artery.

Double right coronary artery with separate ostia

A double right coronary artery was first reported in the literature in 1987 by Gupta et al.Reference Gupta, Abraham, Reddy and Moorthy ¹⁰ The authors dubbed this anomaly as a “supernumerary right coronary artery”. In their study, the two separate vessels arose from the right coronary sinus from two separate ostia adjacent to each other. One of the double right coronary artery vessels had a sinoatrial nodal branch and continued as a posterior descending artery. The other vessel had a conus branch and right ventricular branches, and finally continued as an acute marginal branch.

Overall, there were 18 reported cases of two separate double right coronary arteries of a similar calibre originating from separate ostia in the right sinus of Valsalva (Table 1): 11 cases of “double right coronary artery”,Reference Topaloglu, Aras, Bicer, Ergun, Baser and Korkmaz ^{6 ,} Reference Aydogdu, Ozdemir, Diker, Korkmaz, Sozutek and Kutuk ^{11 –} Reference Chen, Chien and Lee ²⁰ four cases of “duplicated right coronary artery”Reference Egred, Shakespeare, Pennell and Corr ^{21 –} Reference Ciftci, Tacoy and Yazici ²³ or “dual right coronary artery”,Reference Huang, Chen and Chen ²⁴ two cases of “split right coronary artery”,Reference Chen ²⁵ and one case of “supernumerary right coronary artery”.Reference Gupta, Abraham, Reddy and Moorthy ¹⁰

Table 1 Collected case reports of double right coronary artery with separate ostia.

Ant = anterior; ASVD = atherosclerotic vascular disease; CABG = coronary artery bypass surgery; CVD = cardiovascular disease; F = female; HCM = hypertrophic cardiomyopathy; LAD = left anterior descending; LCA = left coronary artery; LM = left main; M = male; MI = myocardial infarction; MPA = main pulmonary artery; MS = mitral stenosis; N = no; n/a = not available; Post- = posterior; RA = right atrium; RCA = right coronary artery; RCS = right coronary sinus; VSD = ventricular septal defect; Y = Yes

Double right coronary artery with a single ostium

There were 28 reported cases characterising two different right coronary arteries arising from a common ostium in the right sinus of Valsalva, with a variable short distance from the proximal trunk (Table 2). In 1994, Barthe et alReference Barthe, Benito and Sala ²⁶ were the first to report two different right coronary arteries arising from a common ostium, coursing down the right atrioventricular groove; they were also the first to use the term “double right coronary artery”. Subsequently, this term has become popular and has been adopted by many authors to label two separate double right coronary arteries of a similar calibre originating from either a single ostium or from separate ostia in the right sinus of Valsalva.Reference Harikrishnan, Bhat and Tharakan ^{12 ,} Reference Altun, Akdemir, Erdogan and Ozbay ²⁷ Of the 28 reported cases originating from a single ostium, 23 were described as a “double right coronary artery”Reference Kunimasa, Sato and Ichikawa ^{4 ,} Reference Barthe, Benito and Sala ^{26 –} Reference Singh and Pandey ⁴³ and five as a “split right coronary artery”.Reference Sawaya, Sawaya and Angelini ^{44 –} Reference Okmen and Okmen ⁴⁶

Table 2 Collected case reports of double right coronary artery with a single ostium.

Ant = anterior; AS = aortic stenosis; ASVD = atherosclerotic vascular disease; CABG = coronary artery bypass surgery; CVD = cardiovascular disease; F = female; LAD = left anterior descending artery; LCA = left coronary artery; LCX = Left circumflex coronary artery; M = male; MI = myocardial infarction; MS = mitral stenosis; N = No; n/a = not available; Post- = posterior; PTCA = percutaneous transluminal coronary angioplasty; RCA = right coronary artery; RV = right ventricle; VT = ventricular tachycardia; MDCT = Multi-detector computed tomography; Y = Yes

Imaging studies for double right coronary artery

Correctly diagnosing this rare anomaly has difficulties. It is almost always accidentally detected during traditional coronary angiography. Altun et alReference Altun, Akdemir, Erdogan and Ozbay ²⁷ reported that the right anterior oblique view during coronary angiography provides the best possibility for differentiating a double right coronary artery from a high take-off of a large right ventricular branch. Several authors have reported the importance of using multi-detector computed tomography for diagnosing this rare congenital anomaly.Reference Kunimasa, Sato and Ichikawa ^{4 ,} Reference Soydinc, Sari and Davutoglu ^{47 ,} Reference Sato, Kunimasa, Matsumoto and Saito ⁴⁸ Multi-detector computed tomography is a cost-effective, non-invasive, and fast imaging tool that is more accurate for defining the origins and course of anomalous coronary artery compared with conventional coronary angiographyReference Sato, Kunimasa, Matsumoto and Saito ⁴⁸ (Fig 1c). However, multi-detector computed tomography can be also harmful because it exposes the patient to considerable amounts of radiation and contrast medium.Reference Sato, Kunimasa, Matsumoto and Saito ⁴⁸ Magnetic resonance coronary angiography is another non-invasive diagnostic tool for assessing proximal coronary anatomy.Reference McConnell, Ganz, Selwyn, Li, Edelman and Manning ⁴⁹ Magnetic resonance imaging holds the greatest appeal because no radiation and less nephrotoxic contrast agents are used.Reference Misuraca, Rutigliano, Pestrichella, Contegiacomo and Balbarini ³⁷

Double right coronary artery and atherosclerosis

Overall, there were 46 reported cases of two separate double right coronary arteries with similar calibre arising from the right sinus of Valsalva and originating from either a single ostium or from separate ostia. Previously, the double right coronary arteryReference Garg, Goel and Sinha ^{15 ,} Reference Nair, Krishnamoorthy and Tharakan ^{28 ,} Reference Tatli, Buyuklu, Altun and Yilmaztepe ^{35 ,} Reference Rohit, Bagga and Talwar ^{36 ,} Reference Soydinc, Sari and Davutoglu ^{47 ,} Reference Sato, Kunimasa, Matsumoto and Saito ⁴⁸ or split right coronary arteryReference Okmen and Okmen ⁴⁶ had been described as a rare benign congenital coronary anomaly that did not warrant special management. Nevertheless, because of the rarity of this anomaly and lack of comprehensive studies, its clinical importance is not yet known. Garg et alReference Garg, Goel and Sinha ¹⁵ reported that a double right coronary artery does not seem to increase the tendency towards atherosclerosis or induce ischaemia. Furthermore, Sato et alReference Sato, Kunimasa, Matsumoto and Saito ⁴⁸ suggested that the clinical significance of double right coronary artery might be minimal because the probability of development of atherosclerosis in patients with a double right coronary artery was equal to that in those without it. Nevertheless, chest pain as the initial presenting symptom was present in 69.6% (32/46) of the reported cases. Imaging studies demonstrated significant stenotic lesions in 26.1% (12/46) of anterior right coronary arteries. Surprisingly, the single ostium group had a much higher incidence (39.3%, 11/28) of stenotic lesions than did the separate ostia group (5.6%, 1/18) (odds ratio [OR], 11.0; 95% confidence interval [CI], 1.28–94.89; p = 0.011) (Table 3 and Fig 1d and e). This result is consistent with the fact that atherosclerotic lesions occur predominantly at sites of low or oscillatory shear stress patterns such as near bifurcation or curved arteries.Reference Dai, Kaazempur-Mofrad and Natarajan ⁵⁰ In contrast, the straight arterial segment exposed to a physiologic shear stress appeared to be protected from atherosclerosis.Reference Cheng, Tempel and van Haperen ⁵¹ In addition, 32.1% (9/28) of the patients in the single ostium group had significant coronary stenosis of the posterior right coronary artery compared with only 5.6% (1/18) in the separate ostium group (OR, 8.1; 95% CI, 1.02–70.33; p = 0.033), and 17.9% (5/28) of the proximal main trunks in the single ostium group showed significant coronary stenosis. The incidence of coronary artery disease involving the right coronary arteries in patients with double right coronary artery was 37.0% (17/46). Interestingly, the occurrence of atherosclerotic stenosis of both right coronary arteries was only 5.6% (1/18) in the separate ostia group, whereas it was up to 57.1% (16/28) in the single ostium group, with the difference being highly statistically significant (OR, 22.7; CI, 2.64–194.82; p < 0.0001). The overall incidence of coronary artery disease involving the right and left coronary arteries was 54.3% (25/46): 27.8% (5/18) in the separate ostia group and 71.4% (20/28) in the single ostium group, with the difference being highly statistically significant (OR, 6.5; CI, 1.74–24.27; p = 0.004). We found no difference as regards the occurrence of coronary artery disease involving the left coronary artery between two groups (OR, 1.4; CI, 0.40–5.24; p = 0.575). Of the patients with double right coronary artery, six had complications with acute inferior wall infarctionReference Timurkaynak, Ciftci and Cengel ^{14 ,} Reference Tatli, Buyuklu, Altun and Yilmaztepe ^{35 ,} Reference Rohit, Bagga and Talwar ^{36 ,} Reference Akcay, Koroglu, Kaya, Koleoglu and Acar ^{40 ,} Reference Acet, Ozyurtlu, Bilik and Ertas ^{42 ,} Reference Sawaya, Sawaya and Angelini ⁴⁴ : five in the single ostium group and one in the separate ostia group. Of the infarcted vessels, four were anterior right coronary arteries and two were posterior right coronary arteries. The aforementioned findings are different from the speculation proposed by Angelini,Reference Angelini ⁵² who described that coronary atherosclerotic changes seem to affect only the atrioventricular (or basal) right coronary artery branch. In summary, although there are no documented studies demonstrating that people with a double right coronary artery are more susceptible to atherosclerotic changes, the possibility of an association between this condition and the increased susceptibility of developing atherosclerosis and or even acute coronary syndromes, including myocardial infarction, remains to be elucidated, especially in patients having double right coronary artery with a single ostium.

Table 3 Characteristics of atherosclerotic CAD and other associated heart diseases in patients with double right coronary artery.

Ant- = anterior; CAD = coronary artery disease; CVD = cardiovascular disease (i.e. associated with other congenital heart disease and acquired heart disease); LCA = left coronary artery; Post- = posterior; RCA = right coronary artery

*The number of RCA with CAD does not necessarily equal that of Ant- plus Post- because the same patient may have both Ant- and Post-CAD

The patients report by Selcoki et alReference Selcoki, Yilmaz, Er and Eryonucu ³⁹ and Garg et alReference Garg, Goel and Sinha ¹⁵ had ST-segment depression in the inferior leads at exercise stress but their coronary arteries were free of atherosclerotic lesions. Thus, in some patients without atherosclerotic stenosis, ischaemia can be a result of anatomical malformation, including the acute take-off angle of the anomalous vessel, with a narrowed slit-like orifice that collapses in a valve-like manner, vasospasm, or myocardial bridging, thereby limiting the blood flow.Reference Ozeren, Aydin, Bilge, Dursun and Onuk ^{31 ,} Reference Selcoki, Yilmaz, Er and Eryonucu ³⁹

Issues during percutaneous coronary intervention

In addition to its being a coronary abnormality, we speculate that double right coronary artery originating from a single ostium might be atherosclerotic and can cause acute coronary syndrome. Coronary interventionists should be aware of this anomaly so as to avoid misinterpreting coronary angiograms and potential procedurally induced complications. According to an interesting double right coronary artery imaging report by Misuraca et al,Reference Misuraca, Rutigliano, Pestrichella, Contegiacomo and Balbarini ³⁷ a coronary angiographic view mimics a coronary dissection because the two separate right coronary arteries arise from a single ostium. The two right coronary arteries were split along both the proximal and the mid-segment and united into a single vessel at the distal segment. The incorrect diagnosis of coronary dissection may potentially be arrived at, and the patient may potentially be mismanaged with harmful treatment, such as the application of a stent. Okmen et alReference Okmen and Okmen ⁴⁶ emphasised that it can be challenging to catheterise the correct artery without blocking the blood flow to the other artery. For this reason, they recommend making the first injection of the contrast as non-selective as possible. Pulling back the catheter slightly before the first or final injection may also reveal the second right coronary artery originating from the same ostium or adjacent ostium. Thus, it is important for the interventional cardiologist to keep in mind this congenital coronary abnormality, in order to prevent an inaccurate diagnosis and incorrect treatment.Reference Sari, Uslu, Gorgulu, Nurkalem and Eren ^{33 ,} Reference Misuraca, Rutigliano, Pestrichella, Contegiacomo and Balbarini ^{37 ,} Reference Sucu, Ozer, San and Davutoglu ³⁸

A total of three patients in the single ostium group had severe atherosclerotic lesions in the double right coronary artery, but percutaneous intervention was difficult because of the highly angulated anatomy of the main trunk of the right coronary system,Reference Sari, Uslu, Gorgulu, Nurkalem and Eren ³³ localisation of the stenotic lesion,Reference Ozeren, Aydin, Bilge, Dursun and Onuk ³¹ or small size of the right coronary artery.Reference Tatli, Buyuklu, Altun and Yilmaztepe ³⁵

Issues during cardiac surgery

Owing to the fact that the surgeon may improperly manage a pre-operatively undefined abnormal coronary artery during surgery, pre-operative recognition of this congenital anomaly is of paramount importance before using cardioplegia during cardiac operation for aortic valve surgery or an aortic root procedure. All the coronary arteries have to be cannulated separately while delivering cardioplegic solution, or they need to be carefully relocated during aortic root surgeries such as the Jatene operation, modified Bentall procedure, valve-sparing root replacement, or the Ross procedure. In addition, cardiac surgeons should also be careful during coronary revascularisation because both the right coronary arteries are usually of similar calibre and size and because their courses may be parallel to each other.Reference Topaloglu, Aras, Bicer, Ergun, Baser and Korkmaz ^{6 ,} Reference Erbagci, Davutoglu, Turkmen, Kizilkan and Gumusburun ^{32 ,} Reference Okmen and Okmen ⁴⁶

Study limitation

Conclusions that can be drawn from our studies are limited by a number of factors. First, our database may be flawed by sampling errors as most reports of this congenital abnormality are detected from coronary angiography, and therefore the results may not be generalisable to the general population. Second, most of these patients had coronary angiograms performed because of chest symptoms; as a consequence, the analysis of differential incidences of coronary artery disease is doubtful. Third, men are more likely to undergo cardiac catheterisation compared with women due to the prevalence of coronary artery disease among the younger cohort. Finally, catheterisation patients are a group with an increased prevalence of coronary artery disease compared with the general population. Thus, the selection bias in our study series is inevitable.