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A catheter-induced syncopal attack in a case of hypertrophic obstructive cardiomyopathy.

A 48-year-old man with hypertrophic obstructive cardiomyopathy (HOCM) was studied by serial cardiac catheterization during incidentally induced syncope. His hospital admission was for repeated syncopal attacks and chest pain. His electrocardiogram showed giant negative T waves (greater than 10 mm) in V3, V4 and V5 leads, and his M-mode echocardiogram disclosed typical asymmetric septal hypertrophy, systolic anterior movement of the mitral valve, and a midsystolic semiclosure of the aortic valve. During cardiac catheterization, we incidentally induced syncope and recorded the serial pressure changes. During syncope, systemic blood pressure dropped without appreciable changes in pulmonary arterial and right ventricular pressures. Although blood pressure was maintained by administering etilefrine and hydrocortisone, syncope persisted. After administration of propranolol, he recovered from syncope. He was on sinus rhythm throughout the examinations. The ejection time (ET) obtained from the aortic pressure curve was extremely short (160 msec) during syncope and prolonged (300 msec) after recovery without significant change in the heart rate. We believe that the prompt intravenous administration of propranolol was very effective in relieving myocardial spasm as a possible cause of syncope.