Clin. Cardiol. 5, 377-381 (1982) zyxwvut 0 Clinical Cardiology Publishing Company, Inc. zyxwvu Case zyxwvutsr Reports Aberrant Origin of the Left Coronary Artery from the Proximal Right Coronary Artery: Diagnostic Features and Pre- and Postoperative Course zyxwv R. R. LIBERTHSON, M.D., L. ZAMAN, M.D.,A. WEYMAN, M.D., R. KIGER, M.D., R. E. DINSMORE, M.D., R. c . LEINBACH, M.D., H. w. STRAUSS, M.D., M. J. BUCKLEY, M.D. Departments of Medicine (Cardiac Unit), Pediatrics, Surgery (Cardiovascular Unit) and the Division of Nuclear Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA Summary: In this report, we present the pre and late postoperative course of a patient with severe angina secondary to aberrant origin or the left coronary artery from the proximal right coronary artery (Fig. 1). We illustrate the noninvasive diagnosis and evaluation of this patient by two-dimensional ultrasound and stress thal- lium imaging, and the pre and late postoperative angi- ographic and thallium perfusion findings. Key words: angina pectoris, beta blockade Case Report A 54-year-old woman was referred for evaluation of angina pectoris which was refractory to maximum medical treatment with both beta blockade and nitrate therapy. Mild exertional chest pain had been present since early adolescence. She had a two-year history of angina pectoris which was increasing in frequency and severity. She required zyxwvutsrq 6 hospitalizations for chest pain during the year prior to admission, but at no time was Address for reprints: Richard R. Liberthson, M.D. Cardiac Unit Massachusetts General Hospital Boston, Massachusetts 021 14, USA Received: March zyxwvutsrqpo 8, 1982 Accepted: March 26, 1982 myocardial infarction diagnosed. Physical examination, chest x-ray and resting electrocardiograms were normal. Two-dimensional echocardiographic examination of the proximal coronary arteries suggested an aberrant left coronary artery arising from the proximal right coronary artery and coursing leftward between the aorta and the right ventricular outflow tract (Fig. 2A,B,C). Graded treadmill exercise stress testing (Bruce protocol) (Bruce et al., 1973) caused typical angina pectoris after 3'/2 min, but was associated with only equivocal ST-T wave ab- normalities which were not diagnostic of ischemia. At peak exercise (5 min) 1.5 mCi of 2°1thallium(201 TLCL in 0.9% saline) was injected intravenously followed by imaging with an Angor scintillation camera and data was recorded on a nuclear medicine computer system. Imaging in the anterior, 45, and 70 degree left anterior oblique projections revealed decreased activity in the anterolateral left ventricular wall immediately following exercise (Fig. 3A). Normal anterolateral wall activity returned on the late images (Fig. 3B). Selective right coronary angiography delineated aberrant origin of the left coronary artery from the proximal right coronary. The left coronary artery passed anteriorly and leftward behind the infundibulum of the right ventricular outflow tract to supply a small left anterior descending and left circumflex artery (Fig. 4A,B). There was no intrinsic coronary artery narrowing. Left ventriculography re- vealed mild hypocontractility of the left ventricular an- terior and lateral walls. Atrial pacing to a heart rate of 125 beats/min caused ST-T wave depression in the an- terolateral electrocardiographic leads suggesting tachycardia induced ischemia which was absent at resting heart rates. zyxw 311