Ann Thorac Surg 2001;71:357-358
© 2001 The Society of Thoracic Surgeons
Case report
Anomalous right coronary artery originating from the left main coronary artery
Steven R. Lopushinskya,
John C. Mullen, MDa,
Michael J. Bentley, BSca
a Division of Cardiothoracic Surgery, The University of Alberta, Edmonton, Alberta, Canada
Accepted for publication March 23, 2000.
Address reprint requests to Dr Mullen, Departments of Surgery and Pediatrics, The University of Alberta Hospital, 2D2.18 WC Mackenzie Health Sciences Centre, 8440-112 St, Edmonton, AB, T6G 2B7 Canada
e-mail: jmullen{at}ualberta.ca
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Abstract
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A 54-year-old man with no cardiac history presented with exertional angina. Cardiac catheterization revealed an anomalous right coronary artery originating from the left main coronary artery with external compression during its course between the aorta and the pulmonary artery. He was successfully managed with surgical reimplantation of the right coronary artery into the aorta.
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Introduction
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Anomalous coronary arteries are rare congenital cardiac defects with varying symptomatology and controversial clinical significance. The incidence of coronary anomalies in the general population has been estimated between 0.3% and 1.3% [1, 2]. There have been three reports of the right coronary artery (RCA) originating from the left main coronary artery (LM) with subsequent symptoms in the absence of atherosclerosis [3–5]. This anomaly often has been dismissed as an incidental finding not linked to myocardial ischemia. We describe the surgical management of a patient suffering severe angina attributed to anomalous origin of the RCA with compression between the aorta and pulmonary artery. The RCA was reimplanted into its normal point of origin in the aorta.
A 54-year-old man presented to the emergency department with a several-month history of unstable angina. Risk factors for coronary artery disease included hypertension and a 60 pack-year history of smoking.
Exercise stress testing was positive with markedly abnormal ST segments. Cardiac catheterization showed a dominant RCA originating from the LM and coursing anteriorly between the aortic root and the main pulmonary artery (Fig 1). There was evidence of external compression of the proximal portion of the RCA during systole. The patient was advanced for operation.
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Fig 1. (A) Coronary angiogram (left anterior oblique projection) showing a normal contour of the anomalous right coronary artery (RCA) during diastole. The RCA originates from the left main (LM) coronary artery in this patient. (B) Coronary angiogram (left anterior oblique projection) showing compression (C) of the RCA during systole as it courses between the aorta and main pulmonary artery (CIRC = circumflex coronary artery; LAD = left anterior descending coronary artery).
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At operation he was placed on cardiopulmonary bypass and the heart was arrested with antegrade cold blood cardioplegia. The RCA was dissected out, divided just after its emergence between the great vessels, and the proximal end was sewn over. The artery was then mobilized sufficiently to allow for anastomosis to the aorta. A button was cut in the anterior surface of the aorta close to the position of a normal RCA origin. The RCA was then reimplanted into the aorta with a running 5-0 polypropylene suture. He came off of bypass easily with excellent right ventricular function. The RCA showed good filling with no evidence of kinking. His postoperative course was uncomplicated. At 18-month follow-up he was markedly improved with no angina.
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Comment
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Single coronary arteries are very rare, with an autopsy incidence of 0.29% [2]; 40% occur in association with other congenital cardiac abnormalities [3]. The RCA originating from the LM accounts for only 0.65% of these anomalies [1]. After branching from the LM, the RCA may course anterior to the pulmonary artery, posterior to the aorta, or more commonly between the great vessels [1].
Right coronary artery anomalies are of controversial significance, sometimes considered interesting but unimportant. However, Virmani and associates [6] found that in 21 patients with this anomaly, 10 died a cardiac death, 5 of which were sudden (4 with no signs of atherosclerosis). There are also reports of this anomaly causing myocardial infarction [3, 4]. Bloomfield and associates [5] describe a case similar to ours in which an anomalous RCA from the LM provoked severe angina in a middle-aged man free of significant atherosclerosis.
Two mechanisms of ischemia have been proposed for this anomaly. The great vessels, which dilate during exercise, may externally compress the coronary [5, 6]. We believe that this was the case in our patient, as the angiogram showed varying compression between systole and diastole. The anomaly likely did not affect the hemodynamics of the heart until the aorta and the pulmonary trunk became sufficiently thickened or enlarged with age [5]. The second proposed mechanism suggests that valvelike ridges and the acute angulation of the artery as it traverses from the left to the right sinus may induce ischemia [6].
Surgical treatment was chosen to alleviate the patient’s angina and to eliminate the risks of myocardial infarction and sudden death. Two of the three previously reported cases showing symptomatic ischemia chose surgical correction. In each case, a single bypass was made to the RCA; one used a saphenous vein graft [5] and the other used an internal mammary artery [3]. Reimplantation of the RCA into the aorta (the technique used here) is a potential lifelong solution and does not require use of an internal mammary artery or saphenous vein. Although technically somewhat more difficult, reimplantation obviates the use of a bypass conduit, which carries an inherent risk of long-term graft occlusion. A potential disadvantage is the very small risk of acute kinking in the RCA, which could lead to a serious myocardial infarction.
An anomalous right coronary artery is a rare finding. When it is associated with cardiac ischemia, surgical treatment is usually indicated. Cardiac catheterization is fundamental for diagnosis. Coronary bypass operation and direct surgical reimplantation are both reasonable surgical treatment options. Direct reimplantation may produce the best long-term result.
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References
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Virmani R., Rogan K., Cheitlin M.D. Congenital coronary artery anomalies: pathologic aspects. In: Virmani R., Forman M.B., eds. Nonatherosclerotic ischemic heart disease. New York: Raven Press, 1989:172-173.
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Abstract
Introduction
