Alpha-adrenoceptor-mediated coronary artery spasm.

Selective coronary arteriography performed on a 41-year-old woman with angina pectoris demonstrated proximal stenosis of the right and left main coronary arteries that was unaffected by nitrate therapy. To exclude coronary artery spasm, the study was repeated, and a striking increase in the narrowing of the right coronary artery was observed. This 90% stenosis was virtually abolished by pretreatment with intravenously given phentolamine hydrochloride. Prolonged alpha-adrenoceptor blockade with phenoxybenzamine hydrochloride improved the patient's exercise tolerance and postexercise electrocardiographic abnormalities when compared to therapy in matched controls given placebo. These observations suggest that alpha-adrenoceptor-mediated coronary artery spasm may mimic organic lesions at coronary arteriography and may be a factor in the pathogenesis of angina pectoris in some patients.