Hemodynamic effects of verapamil in children and adolescents with hypertrophic cardiomyopathy

Abstract

The acute hemodynamic effects of verapamil were evaluated in nine children with hypertrophic cardiomyopathy. Verapamil, 0.1 mg/kg, was administered as a i.v. bolus over 2 minutes, followed by a 20-minute continuous infusion of 0.007 mg/kg/min. Hemodynamic measurements were obtained at rest in nine patients and at maximal supine bicycle exercise in seven before and 15 minutes after verapamil. At rest, verapamil increased the mean cardiac output from 3.3 ± 0.9 to 3.7 ± 0.9 l/min/m2 (± SD) (p < 0.02) and decreased left ventricular end-diastolic pressure from 19.3 ± 8.1 to 14.5 ± 6.9 mm Hg (p < 0.006). In six patients with resting left ventricular outflow tract obstruction, the systolic pressure gradient decreased from 17.5 ± 7.2 to 5.2 ± 4.5 mm Hg (p < 0.04). Repeat supine bicycle exercise testing after verapamil showed increases in total work performed (1743 ± 1284 to 3168 ± 1643 kg-m, p < 0.006) and maximal cardiac index during exercise (6.5 ± 1.3 to 7.8 ± 1.8 l/min/m2, p < 0.05), and decreases in maximal exercise left ventricular end-diastolic pressure (29.1 ± 10.1 to 19.3 ± 10.4 mm Hg, p < 0.002) and left ventricular systolic outflow tract gradient (31.2 ± 10.5 to 1.75 ± 1.7 mm Hg, p < 0.04). These results suggest that verapamil may be an effective therapeutic agent for the treatment of hypertrophic cardiomyopathy in children.