Verapamil therapy: a new approach to the pharmacologic treatment of hypertrophic cardiomyopathy. I. Hemodynamic effects.

The hemodynamic effects of intravenous verapamil administration were examined in 27 patients with hypertrophic cardiomyopathy. Increasing doses of verapamil produced small increases in heart rate and cardiac output and a significant decrease in systolic blood pressure, but had no significance effect on mean pulmonary artery wedge pressure or left ventricular end-diastolic pressure. The highest dose of verapamil increased heart rate from 72 +/- 3 to 81 +/- 6 beats/min and reduced systolic blood pressure from 118 +/- 8 to 99 +/- 5 mm Hg (p less than 0.005). This dose decreased the basal left ventricular outflow tract gradient from 94 +/- 14 to 49 +/- 14 mm Hg and the average left ventricular outflow tract gradient during the Valsalva maneuver from 76 +/- 5 to 63 +/- 13 mm Hg, during amyl nitrite inhalation from 69 +/- 15 to 39 +/- 13 mm Hg, and during isoproterenol infusion from 108 +/- 29 to 70 +/- 21 mm Hg (p less than 0.01). These results indicate that verapamil can significantly decrease left ventricular outflow obstruction in patients with hypertrophic cardiomyopathy and thus may provide an important new therapeutic agent in the treatment of this disorder.