Idiopathic hypertrophic subaortic stenosis. Intraventricular gradient reduction associated with oral guanethidine therapy

Clinical and hemodynamic data prior to and during oral guanethidine therapy in two patients with idiopathic hypertrophic subaortic stenosis are presented. In both patients the systolic intraventricular pressure gradient both at rest and during exercise was reduced following continued guanethidine administration. Concomitantly, computed values for left ventricular effective outflow tract area were significantly larger during the guanethidine studies than during the control studies. The symptomatic patient (Case 1) experienced increased work tolerance and diminished dyspnea on exertion. Guanethidine did not prevent the increased intraventricular gradient and reduction of the aortic pulse pressure which occur during isoproterenol infusion or in the contraction following a premature ventricular beat. It is suggested that chronic guanethidine administration, by reducing the systolic obstruction, may be a useful pharmacologic agent in this disorder.