Acute effects of DDD pacing in patients with pulmonary infundibular stenosis.

We evaluated acute effects of DDD pacing (right atrium sensed and left ventricle paced) in 3 patients with pulmonary infundibular stenosis and found a decrease in dynamic right ventricular outflow gradient in all of them. It appears that acute temporary DDD pacing may decrease the dynamic obstruction of the right ventricular outflow tract in these patients, probably because of asynchronous contraction of the right ventricle induced by pacing from the left ventricular apex, with contraction of infundibular portion being delayed.