The efficacy of right ventricular pacing for symptomatic left mid-ventricular obstruction.

The serial changes in intraventricular pressure gradient in the left ventricle and NYHA functional classification in each case. Both the left intraventricular pressure gradient and symptoms improved after right ventricular pacing. In one case, the left intraventricular pressure gradient disappeared immediately after right ventricular pacing, while in the others it disappeared during the chronic phase, more than a year later.