IMPAIRED EXERCISE RESPONSE AND OTHER RESIDUA OF PULMONARY STENOSIS AFTER VALVOTOMY

Abstract

A hemodynamic study of 13 patients with pulmonary stenosis and of 17 subjected to valvotomy is reported. Impaired exercise response was found in both groups. In the presence of pulmonary stenosis, relative shortening of diastole due to prolonged right ventricular ejection, combined with increased right ventricular filling resistance, appear to be the factors limiting cardiac output increase during exercise. After operation, the factor of increased filling resistance alone may suffice to cause persistence of an abnormal response to effort. the same mechanism appears to be responsible for the occasional continuation of reversed interatrial shunting after valvotomy for severe pulmonary stenosis. Myocardial fibrosls seems to be the cause of increased right ventricular filling resistance, even after complete resolution of hypertrophy. Perpetuation of hypertrophic infundibular stenosis by high residual right ventricular systolic pressure after valvotomy is illustrated by case reports and the importance of the duration and severity of right ventricular hypertension in relation to the production of myocardial fibrosis is stressed. Early and adequate relief of severe right ventricular hypertension is urged, and the question of infundibular muscle resection after pulmonary valvotomy is discussed again in the light of these findings.