The hemodynamic effects of intravenous verapamil in patients on chronic propranolol therapy

Abstract

Concern exists regarding the negative inotropic and chronotropic effects of verapamil given to patients receiving chronic propranolol therapy. In order to evaluate the safety of combined therapy, the hemodynamic effects of verapamil were investigated in a group of 19 patients on chronic propranolol therapy undergoing cardiac catheterization. Hemodynamic measurements and left ventriculography were performed prior to and 30 minutes after initiation of intravenous administration of verapamil. Verapamil doses varied from 0.025 mg/kg to 0.1 mg/kg intravenous bolus injection followed by an infusion of 0.005 mg/kg/min. Following verapamil administration, systolic, diastolic, and arterial mean pressures and systemic vascular resistance decreased significantly. There was no significant change in left ventricular end-diastolic pressure, mean pulmonary capillary wedge pressure, cardiac index, arteriovenous oxygen difference, heart rate, mean velocity of circumferential fiber shortening (VCF), end-diastolic volume index, end-systolic volume index, stroke volume index, and ejection fraction (EF). Stroke work index decreased significantly. Lack of improvement in cardiac index, VCF, and EF and decrease in stroke work index in spite of constant filling pressure and decreased afterload suggest the additive negative inotropic action of verapamil. The depressant action of propranolol itself was not determined by this study. In spite of the negative inotropic effect of verapamil, it can be administered acutely to patients who have been on propranolol therapy with relative safety if the propranolol has not already produced severe left ventricualr dysfunction, relative hypotension, bradyarrhythmia, or conduction abnormalities.