Assessment of residual right ventricular outflow tract obstruction following surgery using the response to intravenous propranolol

The response to intravenous administration of propranolol hydrochloride was studied in 24 children undergoing operation for isolated or complex right ventricular outflow tract obstruction. Ten had pulmonary valve stenosis, 4 had pulmonary valve stenosis plus ventricular septal defect, 8 had tetralogy of Fallot, and 2 had complex lesions. Propranolol (0.01 to 0.2 mg per kilogram of body weight) was given to patients with a residual right ventricular to left ventricular systolic pressure ratio greater than 0.75. Four children did not respond to propranolol and required further surgical intervention. Twenty patients responded, 2 of whom died. Fifteen were restudied by cardiac catheterization 3 weeks to 27 months postoperatively. The right ventricle-pulmonary artery gradient was 25 mm Hg or less in 13 patients. We conclude that a small dose of propranolol given intraoperatively can identify patients in whom a reduction in the right ventricle-pulmonary artery gradient to acceptable levels will occur in the months following operation. This may reduce the need for placement of a subannular or transannular patch in some patients.