Recurrent syncope induced by left ventricular outflow tract obstruction: demonstration in a patient with hypertrophic obstructive cardiomyopathy.

A 70-year-old man presented with repeated syncope induced by left ventricular outflow tract obstruction. He was referred to us because of repeated syncope with convulsion at rest. During syncope, electrocardiography showed marked ST segment depression with negative T waves in leads I, II, aVL, aVF and V2-V5 but no arrhythmias. Echocardiography revealed asymmetric septal hypertrophy and complete obstruction of the left ventricular outflow tract due to systolic anterior movement of anterior mitral leaflet and concomitant severe mitral regurgitation. During the catheterization study, syncope with convulsion developed repeatedly without antecedent cause, and was associated with a decrease in systemic blood pressure. Simultaneous pressure monitoring of the left ventricle and femoral artery showed a significant pressure gradient (maximum 110 mmHg). During each episode, systemic blood pressure rose spontaneously with the recovery of consciousness over several minutes. He received temporary atrioventricular sequential pacing and underwent successful mitral valve replacement. Four years later, he was doing well.