A Single Coronary Artery Anomaly: Right Coronary Artery Originating from the Mid Left Anterior Descending Artery

ABSTRACT: We present three cases of a single coronary artery that is the anomalous RCA originating from the mid LAD artery. These cases are rare. We discuss how to make accurate diagnosis and select appropriate treatment.

J INVASIVE CARDIOL 2011;23:258–260

Key words: anomalous right coronary artery, coronary artery anomaly, single coronary artery, coronary angiography, CT

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Coronary artery anomalies are present at birth, but they are usually asymptomatic and found incidentally during coronary angiography. Their prevalence is less than 0.024–0.044% based on published articles.^1–3 The most common coronary anomaly is the separate origination of the left anterior descending artery (LAD) and left circumflex artery (LCX) from the left sinus of Valsalva. The second most common anomaly is the LCX artery originating from the right coronary artery (RCA). The anomalous RCA often originates from the left sinus or from the proximal left main coronary artery (LMCA). In this case report, we present three cases of a single coronary artery that is the anomalous RCA originating from the mid LAD artery. These cases are rare. We discuss how to make an accurate diagnosis, and how to make an appropriate treatment.

Case Reports

Patient #1. A 77-year-old woman was admitted to the cardiology department with post-exertion angina pectoris (after exertion) for one month. Physical examination was normal. Electrocardiogram (ECG) showed ST depression in leads II, III, and aVF; echocardiogram was normal (nonspecific). Coronary angiography was performed through transfemoral approach, and only a solitary ostium could be cannulated, which came off the LMCA. LAD and LCX arteries derived from the LMCA, and the RCA was derived from the mid LAD (Figures 1A and 1B). The single coronary artery anomaly was classified as type L-II-A. There were severe stenoses in the proximal and mid portions of the anomalous RCA; two stents were implanted, and a -good final result was seen on angiography (Figure 1C). A multi-slice computed tomography (MSCT) of the heart was performed on a 64-slice machine (Somatom Sensation 16, Siemens, Germany) 12 months after percutaneous coronary intervention. The results showed there were no in-stent restenoses, and that the anomalous RCA was located in front of and inferior to the pulmonary artery, then turned down to the surface of the right ventricle (Figure 1D). The patient was free of chest pain at 16-month follow-up exam.

Patient #2. A 72-year-old woman presented with chest pain after physical exercise. Electrocardiogram showed ST-segment depression in precordial leads V4–6. The patient underwent cardiac catheterization because of unstable angina. Angiography demonstrated that all three major coronary arteries originated from the same ostium of the left sinus (Figure 2A). The single coronary artery anomaly was also classified as type L-II-A. The left main stem was patent, but there was 80% stenosis in the proximal segment of the LAD, and 70% stenosis in the mid segment of the LCX. The anomalous RCA, which originated from the mid segment of the LAD, was a dominant and patent vessel (Figure 2B). One stent was implanted at the mid segment of the LCX and two stents were deployed at the mid segment of the LAD. The final angiographic result was excellent and the anomalous RCA was not impaired (Figure 2C). MSCT of the heart was performed on a 64-slice machine (Philips 64 Slice, Philips Healthcare, Cleveland, Ohio) 6 months later. The images demonstrate that the anomalous RCA originates from the mid segment of the LAD, and is located in front of and inferior to the pulmonary artery, then takes a bend down to the surface of the right ventricle (Figure 2D). She was free of chest pain at 12-month follow-up exam.

Patient #3. A 77-year-old man was admitted to the cardiology department with angina pectoris after exertion for one month. Physical examination was normal. ECG showed ST depression in leads II, III, and aVF; echocardiography was nonspecific. Coronary angiography was performed via transradial approach; only a solitary ostium could be cannulated, giving off branches to the LMCA, LAD, LCX, and RCA, which derived from the mid segment of the LAD (Figures 3A–3D). The single coronary artery was classified as type L-II-A. There were severe stenotic lesions in the proximal and mid segments of the anomalous RCA, and severe narrowing in the mid LAD and mid LCX arteries. Non-interventional management was chosen and the patient was transferred to the cardiovascular surgery department for coronary artery bypass graft surgery. He was free of chest pain at a 3-month follow-up examination.

Discussion

Coronary artery anomalies are present at birth, but they are usually asymptomatic and are found incidentally during coronary angiography. Their prevalence is less than 0.024–0.044% based on published articles.^1–3 The most common coronary anomaly is the separate origination of the LAD and LCX from the left sinus of Valsalva. The second most common anomaly is the LCX artery originating from the RCA. The anomalous RCA often originates from the aortic trunk of ascending artery or left sinus of Valsalva. The cases we present are single coronary artery anomalies (SCA); these cases are rare, occurring in approximately 0.024% of the population according to Lipton’s reports.¹ The various patterns of SCA are difficult to understand. The anomalous coronary artery is first designated with “R” or “L” depending upon whether the ostium is located in the right or left sinus of Valsalva. It is then designated as group I, II, or III. Group I has anatomical course of either a right or left coronary artery. Group II anomalies arise from the proximal part of the normal right or left coronary artery, and cross the base of the heart before assuming the normal position of the inherent coronary artery. Group III describes the anomaly where the LAD and LCX arise separately from the proximal part of the normal RCA. Five anatomical subtypes exist, and are classified according to the relationship of the anomalous coronary artery with the aorta and pulmonary artery, i.e., “anterior,” “between,” “septal,” “posterior,” or “combined.” In this series, the septal subtype was the most common, whereas the between type was rare (Table 1).^1–3 The cases reported are all anomalous RCA originating from the mid LAD segment, and classified as type L-II-A.

Coronary anomalies are usually detected during coronary angiography. However, x-ray angiography is limited by its inability to provide information regarding the spatial orientation of the anomalous artery with regard to the surrounding cardiovascular structures.^4,5 MSCT has the potential to accurately visualize the coronary artery6 and clearly demonstrate the surrounding cardiovascular structures of the anomalous coronary artery.⁷ In the first two cases presented, MSCT images clearly demonstrated the origin and course of the anomalous RCA (i.e., in front of and inferior to the pulmonary artery, then taking an acute bend to the surface of the right ventricle).⁸

References

1. Lipton MJ, Barry WH, Obrez I, et al. Isolated single coronary artery: Diagnosis, angiographic classification, and clinical significance. Radiology 1979;130:39–47.
2. Yamanaka O, Hobbs RE. Coronary artery anomalies in 126,595 patients undergoing coronary arteriography. Cathet Cardiovasc Diag 1990;21:28–40.
3. Desmet WJ, Vanhaeche J, Vrolix M, et al. Isolated single coronary artery: A review of 50,000 consecutive coronary angiographies. Eur Heart J 1992;13:1637–1640.
4. Ishikawa T, Brandt PW. Anomalous origin of the left main coronary artery from the right anterior aortic sinus: Angiographic definition of anomalous course. Am J Cardiol 1985;55:770–776.
5. Serota H, Barth CW 3rd, Seuc CA, et al. Rapid identification of the course anomalous coronary artery in adults: The “dot and eye” method. Am J Cardiol 1990;65:891–898.
6. Schmid M, Achenbach S, Ropers D, et al. Assessment of changes in non-calcified atherosclerotic plaque volume in the left main and left anterior descending coronaries over time by 64-slice computed tomography. Am J Cardiol 2008;101:579–584.
7. Rodenwalt J. Multi-slice computed tomography of the coronary arteries. Eur Radiol 2003;13:748–757.
8. Xuguang Q, Weiguo X, Chunpeng L. The coronary anomaly: Right coronary artery originates from the mid left anterior descending (LAD) artery. J Invasive Cardiol 2010;22:E166–E167.

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From ¹Huashan Hospital, Fudan University and ²First Affiliated Hospital of Tsinghua University, Beijing, China.
The authors report no conflicts of interest regarding the content herein.
Manuscript submitted November 4, 2010, provisional acceptance given November 29, 2010, final version accepted January 26, 2011.
Address for correspondence: Dr. Qin Xuguang, 0712, Doctorate Huaxin Hospital, Department of Cardiology, 1st Street No. 6, Jiuxianqiao, Wangjing West Road, Chaoyang, Beijing 100016, China. Email: qin-xuguang0712@163.com