Right Coronary Artery Anatomical Variants: Where and How?

ABSTRACT: Background. Ectopic origin of the right coronary artery (RCA) occurs in ≈1.0% of studied populations. We investigated the prevalence and location of ectopic RCAs among patients undergoing coronary angiography (CA) and assessed its effects on resource utilization. Methods. Cases of ectopic RCAs were prospectively collected over 21 months among patients undergoing cardiac catheterization at a University Hospital. “Ectopic RCA” was defined as a RCA originating outside the posterior two-thirds of the right coronary sinus. Results. The study population included 2,120 patients, of which 23 (1.1%) had ectopic RCAs. Of these, 15 (65%) originated from the anterior third of the right sinus, while 8 (35%) originated from the anterior half of the left sinus. Mean procedure and fluoroscopy times were 60 ± 33 and 15 ± 12 minutes (min) for the former, and 78 ± 35 and 31 ± 20 min for the latter, while mean contrast volume for CA was 112 ± 62 ml and 192 ± 85 ml, respectively. 26% required a second CA or a second intervention to image the RCA. Conclusion. Ectopic RCAs pose a clinical problem, consuming time and resources. The search for an ectopic RCA should have Material and Methods Between July 2007 and March 2009, all cases of “ectopic RCA” reported by the performing physicians or noted upon daily film review by the director of the cardiac catheterization laboratory were prospectively collected. Ectopic RCAs were defined as: a) RCAs originating outside the posterior two-thirds of the right sinus. b) Vessel could not be selectively or nonselectively imaged by conventional right coronary catheters (Judkins right 3–5, Amplatz right 1, left coronary bypass or left internal mammary artery [LIMA] catheters). Excluded were “high takeoff” or “low takeoff” RCAs originating from the posterior two-thirds of the right sinus. In the subset of patients in whom the angiogram suggested an ectopic or anomalous RCA, we reviewed other imaging modalities that could potentially enhance the ability to confirm the anatomical location of the ectopic RCA (transthoracic [n = 21] and transesophageal [n = 5] echocardiography, cardiac computed tomography [CT] [n = 3] and magnetic resonance imaging [MRI] [n = 1]). In the process of data collection, the angiograms were reviewed again by two cardiologists assisted by a noninvasive imaging expert. Data regarding fluoroscopy and procedure times as well as contrast volume were extracted from the patient procedure records.

Results

Prevalence (Table 1). The study population included 2,120 patients who underwent CA. Of these patients, 23 (1.1%) had ectopic RCAs: 15 (65%) originated from the anterior third of the right sinus, while 8 (35%) originated from the anterior half of the left sinus. All 8 ectopic RCAs originating from the left sinus of Valsalva ran an interarterial course (between the aorta and pulmonary artery). Only 1 of these patients had symptoms of ischemia of the RCA territory related to a de novo atherosclerotic mid-RCA lesion (which was stented). There was not a single case of ectopic RCA originating from the noncoronary sinus or the posterior half of the left sinus. Final distribution of the RCA as well as the origin and distribution of the left coronary arteries were normal in all 23 cases. Resource utilization. Mean procedure time was 60 ± 33 minutes (min) for the anteriorly displaced RCA, while it was 78 ± 35 min for the RCA originating from the left coronary sinus. Fluoroscopy times were 15 ± 12 min and 31 ± 20 min, respectively. Mean contrast volume used was 112 ± 62 ml for the former group and 192 ± 85 ml for the latter group. While transesophageal echocardiography was very helpful in confirming the location of the orifice of all ectopic RCAs, CT angiography and MRI besides clearly delineating the orifice were helpful in delineating the course and lumen irregularities of ectopic RCAs originating from the left coronary cusp. Catheter selection. Ectopic RCA from anterior third of the right sinus. The average number of diagnostic catheters utilized to selectively image the RCA in this group was 3.3 ± 0.9. These “anteriorly displaced RCAs” could not be visualized with conventional right coronary catheters and were selectively imaged with an Amplatz left 0.75–1 in 80% of the cases and by an Amplatz right 2 in 20% of the cases. Ectopic RCA from the anterior half of the left sinus. In all of these cases the ectopic RCA was originating from the anterior half of the left cusp, either anteriorly or superiorly to the LMCA. A wide variety of diagnostic and interventional catheters were used to selectively image these arteries including Multipurpose 1–2 (50%), XB, Voda guiding 3–4 (37.5%), and Amplatz left 2–3 (12.5%). Incomplete procedures. The initial operator failed to image the ectopic RCA in 26% of the cases, which mandated a second angiogram or a second interventionist to conclude the imaging of the RCA. This failure was somewhat higher among ectopic RCAs originating from the left sinus (37.5% versus 20%).

Discussion

The importance of anteriorly displaced RCA. Figure 1 shows the relative frequency of RCA location based on pathological series.12,13 Former pathological studies suggest that RCAs originate from the posterior, middle and anterior thirds of the right sinus at frequencies of 59%, 40% and 1%, respectively.1 These studies confirm the importance of anteriorly displaced RCAs as the most prevalent anatomical variant among patients undergoing coronary angiography. This clinically benign variant is difficult to image with conventional right coronary catheters or even subselective imaging (Figure 2). This difficulty can potentially translate into prolonged fluoroscopy and procedure times, high contrast loads, excessive use of catheters and incomplete coronary studies. Since this entity occurs in ≈1% of our patients, it can potentially pose a problem, even for experienced operators; it should be acknowledged and appropriately approached by all cardiologists. To selectively image ectopic RCAs in this location, the optimal catheter is the Amplatz left 0.75–1.14 In the 30º right anterior oblique projection (Figure 3B), the catheter should be pointing anteriorly (to the right) and slightly caudal. The importance of RCAs originating from the left sinus (Figure 4). These rare (≈0.1%15,16) anomalies present an imaging and interventional challenge and occasionally have been associated with clinical syndromes of ischemia, myocardial infarction and sudden cardiac death19,20 (usually without previous warning symptoms). However, most of these patients are asymptomatic. These vessels run almost always an interarterial course (between the aorta and the pulmonary artery), and especially when originating superior to the LMCA, may run within the aortic wall tunica media.21,22 In this initial segment, the ectopic RCA may assume an eccentric slit-like appearance that could be mistaken for an atherosclerotic lesion.23 These coronary vessels may also be under considerable external systolic and diastolic pressure, subjecting the patient to ischemia and arrhythmic death. These RCAs should be thoroughly investigated anatomically and functionally.24,25 These ectopic RCAs can be frequently subselectively imaged by an injection into the left sinus and may originate anteriorly, superiorly, adjacent to or directly from the LMCA, but practically never posteriorly to the LMCA. A long list of diagnostic and interventional guiding catheters can be used to image these arteries including Multipurpose 1–2, XB and Voda guides, and Amplatz left series. Areas from which RCAs rarely, if ever, originated. Although two angiographic series26,27 have reported cases of an RCA originating from the noncoronary (posterior) sinus, these findings have not been validated by pathology or precise and objective imaging modalities like CT,28,29 angiography, MRI,30 echocardiography31 or transesophageal echocardiographic32 series. High-takeoff RCAs. Pathological series33 have revealed that high-takeoff RCAs (defined as RCAs originating > 10 mm superior to the sinotubular junction [STJ]) are encountered less frequently (14%) than high-takeoff left coronary arteries (36%). High-takeoff RCAs usually do not present an imaging challenge during CA since they can be imaged subselectively by a right sinus injection, and selectively by conventional right diagnostic catheters (Judkins right 3.5–4, Amplatz right 1–2 or Williams [no-torque] curves). Suggested algorithm when looking for an ectopic RCA. A simplified algorithm for selectively imaging an ectopic RCA has been proposed by Jim et al.34 We recommend a somewhat different three-step algorithm when attempting to image an ectopic RCA: 1) Stage 1. After failing to selectively image the RCA with conventional RCA diagnostic catheters, perform a right sinus injection at the left anterior oblique 30–40º projection (or biplane imaging when available) using a diagnostic Judkins right 4 catheter. This injection should delineate RCAs originating from the posterior two-thirds of the right sinus and will provide information regarding takeoff and orientation of these RCAs. If the RCA cannot be visualized at all, proceed to Stage 2. 2) Stage 2. Use an Amplatz left 0.75–1 (depending on the size of the aorta), and in the right anterior oblique projection 30–40º, with the catheter pointing anteriorly and slightly caudal, attempt to image the RCA originating from the anterior third of the right coronary sinus (also known as an “anteriorly displaced RCA”). If subselective injections fail to image the RCA at this location, it is very likely that the RCA originates from the anterior half of the left sinus, hence, it is necessary to proceed to Stage 3. 3) Stage 3. Using the same Amplatz left 1 (or other left diagnostic catheter) in left anterior oblique 30–40º projection, inject subselectively into the left coronary sinus adjacent but anteriorly to the left coronary ostium. If the RCA cannot be seen, repeat the injection above the left coronary ostium to image the ectopic RCA with a higher left sinus takeoff. If the above steps are unsuccessful, one can obtain an aortogram in the left anterior oblique 40º projection (or biplane if available) or use other imaging modalities (CT angiography, MRI and echocardiography). Study limitations. This study reported cases of ectopic RCAs by reviewing the database of patients who underwent coronary angiography for various indications and can potentially underestimate (by underreporting) or overestimate (by selection bias) the true prevalence of ectopic RCAs in an ambulatory population. Since the borders of the anteriorly displaced RCA are not clearly defined, this diagnosis was based on catheter orientation and on the requirement of special catheters to image the RCA, and was not validated in most cases by precise anatomical imaging modalities like CT, MRI or echocardiography. Inter- and intraobserver variability was not evaluated. The number of incomplete CA procedures and their impact on resource utilization may have been underestimated since 16 out of the 24 cases were performed by a single operator who did not have any incomplete CA studies and required less fluoroscopy time, contrast volume and diagnostic catheters to image the ectopic RCAs.

Conclusions

1) Ectopic RCAs are encountered quite frequently (> 1% of CAs) and can cause excessive use of catheterization laboratory resources. They may also result in incomplete studies and interventional procedures. 2) Searching for these ectopic vessels should be limited to 90º boundaries of the anterior third of the right sinus and anterior half of the left sinus. This search can be facilitated by utilizing our proposed algorithm. Acknowledgements. The authors would like to acknowledge Carol Ann Baker and Cynthia Cruz, RN, for their assistance in obtaining the procedural data of this report.

_____________________________________________ From the Division of Cardiology, Departments of Medicine, University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Newark New Jersey. The authors report no conflicts of interest regarding the content herein. Manuscript submitted August 20, 2009, provisional acceptance given October 6, 2009, final version accepted November 3, 2009. Address for correspondence: Edo Kaluski, MD, FACC, FESC, FSCAI, Director of Cardiac Catheterization Laboratories & Invasive Cardiology, Associate Professor of Medicine, University of Medicine, University Hospital and University of Medicine and Dentistry of New Jersey, 185 South Orange Avenue, MSB- I-538, Newark, NJ 07101–1709. E-mail: kalusked@umdnj.edu

_____________________________________________

References

1. Villalonga JR. Anatomic variations of coronary arteries. The most frequent variations. Eur J Anatomy 2003 (Suppl 29–41). 2. Dodd JD, Ferencik M, Liberthson RR, et al. Congenital anomalies of coronary artery origin in adults: 64-MDCT appearance. Am J Roentgenol 2007;188:W138–W146. 3. Cieslinski G, Rapprich B, Kober G. Coronary anomalies: Incidence and importance. Clin Cardiol 1993;16:711–715. 4. Garg N, Tewari S, Kapoor A, et al. Primary congenital anomalies of the coronary arteries: A coronary arteriographic study. Int J Cardiol 2000;74:39–46. 5. Kardos A, Babai L, Rudas L, et al. Epidemiology of congenital coronary artery anomalies: A coronary arteriography study on a central European population. Cathet Cardiovasc Diagn 1997;42:270–275. 6. Grollman JH Jr, Mao SS, Weinstein SR. Arteriographic demonstration of both kinking at the origin and compression between the great vessels of an anomalous right coronary artery arising in common with a left coronary artery from above the left sinus of Valsalva. Cathet Cardiovasc Diagn 1992;25:46–51. 7. Yans J, Kumar SP, Kwatra M. Anomalous origin of the right coronary artery above the left sinus of Valsalva. Cathet Cardiovasc Diagn 1978;4:407–412. 8. Husaini SN, Beaver WL, Wilson IJ, et al. Anomalous right coronary artery arising from left mainstem. Cathet Cardiovasc Diagn 1983;9:407–409. 9. Rath S, Battler A. Anomalous origin of the right coronary artery from the left anterior descending coronary artery. Cathet Cardiovasc Diagn 1998;44:328–329. 10. Ayala F, Badui E, Murillo H, et al. Right coronary ostium agenesis with anomalous origin of the right coronary artery from an ectatic circumflex artery. A case report. Angiology 1995;46:637–639. 11. Cheatham JP, Ruyle NA, McManus BM, et al. Origin of the right coronary artery from the descending thoracic aorta: Angiographic diagnosis and unique coronary artery anatomy at autopsy. Cathet Cardiovasc Diagn 1987;13:321–324. 12. Banchi A. Morphologia delle arteriae coronariae cordis. Arch Ital Anat Ebriol 3:87–164 13. Hackensellner HA, Koronaranomalien unter 1000 auslesefrei untersuchten Herzen. Anat Anz 1954;101:123–130. 14. Yip H, Chen MC, Wu CJ, et al. Primary angioplasty in acute inferior myocardial infarction with anomalous-origin right coronary arteries as infarct-related arteries: Focus on anatomic and clinical features, outcomes, selection of guiding catheters and management. J Invasive Cardiol 2001;13:290–297. 15. Ayalp R, Mavi A, Sercelik A, et al. Frequency in the anomalous origin of the right coronary artery with angiography in a Turkish population. Int J Cardiol 2002;82:253–257. 16. Harikrishnan S, Jacob SP, Tharakan J, et al. Congenital coronary anomalies of origin and distribution in adults: A coronary arteriographic study. Indian Heart J 2002;54:271–275. 17. Angelini P, Velasco JA, Flamm S. Coronary anomalies: Incidence, pathophysiology, and clinical relevance. Circulation 2002;105:2449–2454. 18. Cheitlin MD, De Castro CM, McAllister HA. Sudden death as a complication of anomalous left coronary origin from the anterior sinus of Valsalva, A not-so-minor congenital anomaly. Circulation 1974;50:780–787. 19. Taylor AJ, Rogan KM, Virmani R. Sudden cardiac death associated with isolated congenital coronary artery anomalies. J Am Coll Cardiol 1992;20:640–647. 20. Benson PA. Anomalous aortic origin of coronary artery with sudden death: Case report and review. Am Heart J 1970;79:254–257. 21. Zhang LJ, Wu SY, Huang W, et al. Anomalous origin of the right coronary artery originating from the left coronary sinus of valsalva with an interarterial course: Diagnosis and dynamic evaluation using dual-source computed tomography. J Comput Assist Tomogr 2009;33:348–353. 22. Ichikawa M, Sato Y, Komatsu S, et al. Multislice computed tomographic findings of the anomalous origins of the right coronary artery: Evaluation of possible causes of myocardial ischemia. Int J Cardiovasc Imaging 2007;23:353–360. 23. Sato Y, Inoue F, Kunimasa T, et al. Diagnosis of anomalous origin of the right coronary artery using multislice computed tomography: Evaluation of possible causes of myocardial ischemia. Heart Vessels 2005;20:298–300. 24. Angelini P, Flamm SD. Newer concepts for imaging anomalous aortic origin of the coronary arteries in adults. Catheter Cardiovasc Interv 2007;69:942–954. 25. Angelini P. Coronary artery anomalies: An entity for search of identity. Circulation 2007;115:1296–1305. 26. Topaz O, DeMarchena EJ, Perin E, et al. Anomalous coronary arteries: angiographic findings in 80 patients. Int J Cardiol 1992;34:129–138. 27. Yamanaka O, Hobbs RE. Coronary artery anomalies in 126,595 patients undergoing coronary arteriography. Cathet Cardiovasc Diagn 1990;21:28–40. 28. van Ooijen PM, Dorgelo J, Zijlstra F, et al. Detection, visualization and evaluation of anomalous coronary anatomy on 16-slice multidetector-row CT. Eur Radiol 2004;14:2163–2171. 29. de Jonge GJ, van Ooijen PM, Piers LH, et al. Visualization of anomalous coronary arteries on dual-source computed tomography. Eur Radiol. 2008;18:2425–2432. 30. McConnell MV, Ganz P, Selwyn AP, et al. Identification of anomalous coronary arteries and their anatomic course by magnetic resonance coronary angiography. Circulation 1995;92:3158–3162. 31. Lytrivi ID, Wong AH, Ko HH, et al. Echocardiographic diagnosis of clinically silent congenital coronary artery anomalies. Int J Cardiol 2008;126:386–393. 32. Fernandes F, Alam M, Smith S, Khaja F. The role of transesophageal echocardiography in identifying anomalous coronary arteries. Circulation 1993;88:2532–2540. 33. Vladover Z, Neufeld HN, Edwards JE. Coronary Arterial Variations in Normal Heart and in Congenital Heart Disease. New York: Academic Press, pp. 19–22. 34. Jim MH, Siu CW, Ho HH, et al. Anomalous origin of right coronary artery from the left coronary sinus: Incidence, characteristics, and a systematic approach for rapid diagnosis. J Interv Cardiol 2005;18:101–106.