RELIEF OF LEFT-VENTRICULAR OUTFLOW TRACT OBSTRUCTION FOLLOWING INADVERTENT LEFT-VENTRICULAR APICAL PACING IN A PATIENT WITH HYPERTROPHIC CARDIOMYOPATHY

Dual chamber (DDD) pacing improves symptoms and relieves left ventricu lar (LV) outflow obstruction in hypertrophic cardiomyopathy. The ventr icular lead is usually positioned at the right ventricular apex (RVA). We report a patient in whom the ventricular lead had inadvertently pe netrated the septum, resulting in DDD pacing from the LV apex. However , after 3 months, obstruction was reduced and symptoms were improved. Pacing from LV apex and RVA resulted in comparable hemodynamic improve ment. This case suggests that the asynchronous wave of septal contract ion, originating from the apex, irrespective of ventricular site, acco unts for the reduction in LV outflow obstruction.