Regression after open valvotomy of infundibular stenosis accompanying severe valvular pulmonic stenosis.

Three patients operated upon under hypothermia for severe valvular pulmonic stenosis had right ventricular pressures in excess of 100 mm. Hg after open valvotomy. The residual obstruction, localized by pressure measurements to the subvalvular region, appeared to be due to greatly hypertrophied musculature in the outflow tract of the ventricle. Infundibular resection was not attempted. Electrocardiographic signs of right ventricular hypertrophy gradually disappeared, and cardiac catheterization about 1 year after surgery showed normal or nearly normal right ventricular pressures. Postoperative improvement is attributed to regression of hypertrophy of the right ventricle consequent to relief of obstruction at the valve.