Verapamil has been used clinically as an antiarrhythmic and antianginal agent. However, the intrinsic negative inotropic properties of verapamil could preclude its use in patients with coronary artery disease concurrently receiving β-adrenergic blocking agents. To investigate this possibility, 20 patients with coronary artery disease and normal left ventricular function receiving chronic propranolol therapy were given i.v. verapamil (0.025, 0.05, or 0.1 mg/kg over 2 minutes, followed by 0.005 mg/kg/min infusion) and the hemodynamic and angiographic effects were studied. The mean (± SD) plasma verapamil concentration at the time the hemodynamic effects were being measured was 122 ± 51 ng/ml for the 10 patients who received low doses (0.025 or 0.05 mg/kg) and 214 ± 108 ng/ml for the 10 patients who received high doses (0.1 mg/kg). Verapamil reduced mean arterial pressure by 22% (p <0.001), systemic vascular resistance by 24% (p <0.001), mean pulmonary artery pressure by 16% (p <0.01), and pulmonary vascular resistance by 23% (p <0.001) in all 20 patients. Concomitant increases in cardiac index, mean velocity of circumferential fiber shortening, and ejection fraction (due to the unloading effect of verapamil) were not observed. These results were not significantly different between the two dosage levels. The combined negative inotropic effects of verapamil and propranolol are of negligible importance; however, the lack of improvement in the indexes of the left ventricular function suggests some myocardial interaction of these two drugs, which may be of concern in cardiac patients with evidence of depressed myocardial performance.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)