Pulmonary valvulotomy alone for pulmonary stenosis: results in children with and without muscular infundibular hypertrophy.

Pulmonary valvulotomy for valvular pulmonic stenosis has been performed in 78 children at the Children's Hospital of Pittsburgh. Although 27 patients had muscular hypertrophy of the infundibulum, a muscle resection was employed in only one child. Examinations 2 to 18 years after operation have not demonstrated electrocardiographic (ECG) or clinical evidence of persistent right ventricular hypertension, indicating resolution of the muscular outflow tract narrowing. Systolic right ventricular pressure averaged 30 mm Hg in 10 patients at postoperative catheterization: Six of these patients had peak right ventricular pressures greater than 100 mm Hg immediately after valvulotomy. The diameter of the infundibulum in systole was compared to valve ring diameter and expressed as a ratio (I/V). This correlated with the preoperative and intraoperative right ventricular pressures, but did not identify patients who might fail to resolve secondary muscular hypertrophy. A murmur of pulmonary regurgitation was present in 70% of the patients after operation, but was without clinical significance. In the absence of fixed infundibular obstruction or excessive right ventricular hypertension above 200 mm Hg, resection of infundibular hypertrophy is not recommended.