Effect of verapamil on left ventricular isovolumic relaxation time and regional left ventricular filling in hypertrophic cardiomyopathy

The effect of verapamil on global and regional left ventricular relaxation as well as on regional left ventricular filling was measured in 11 patients with hypertrophic obstructive or nonobstructive cardiomyopathy in a combined phonocardiographic and echocardiographic study. Five to 10 minutes after intravenous injection of verapamil (0.15 mg/kg body weight) prolonged isovolumic left ventricular relaxation time, measured from the aortic component of the second heart sound to the mitral valve opening in the echocardiogram, significantly decreased from 93 ± 10 to 67 ± 15 ms (p <0.001). This reduction during that time period was associated with a smaller increase in regional left ventricular dimension (3.8 +- 1.9 to 2.4 ±1.4 mm, p < 0.005). Left ventricular filling improved significantly with regard to the peak rate of posterior wall thinning, which increased from 64 +- 30 to 89 ± 38 mm/s, p < 0.001, the Increase in left ventricular dimension during the left ventricular filling period from 14.4 ± 2.4 to 16.4± 2.4 mm; p < 0.01) and the duration of the relative filling period from 47.2± 4.6 to 49.0 ± 5.3 percent; p <0.01). Left ventricular end-systolic dimension, fractional shortening of the left ventricular minor axis, cycle length and systolic blood pressure showed no significant change.

These data show that an abnormal prolongation of the left ventricular relaxation time in patients with hypertrophic cardiomyopathy can be significantly shortened by intraveneus application of verapamil and that this treatment is associated with an improvement of left ventricular filling.