Effect of intravenous verapamil on exercise tolerance and left ventricular function in patients with severe exertional angina pectoris.

The hemodynamic effects of 0.1 mg/kg verapamil given intravenously to 7 patients with angina pectoris were studied at rest and during exercise in the supine position. Cardiac output was measured with the thermodilution technique, which permitted measurements every 30 sec during exercise. Maximal exercise tolerance increased significantly after verapamil. Verapamil had no effect on heart rate at rest, but significantly increased it at the end of the exercise. Left ventricular systolic pressure was reduced by verapamil at rest and during submaximal exercise. Left ventricular end-diastolic pressure was not influenced by verapamil at rest, but was significantly lowered during submaximal exercise. Stroke work index and left ventricular power index were not influenced by verapamil. Rate pressure product was lowered by verapamil during submaximal exercise but had a tendency to be increased at the breaking point. Verapamil had no negative inotropic effect as judged from the left ventricular function curve. It is suggested that the beneficial effect of verapamil relates mainly to a reduction of left ventricular pre- and after-load. The slightly higher rate pressure product after verapamil may also suggest a slight improvement of myocardial perfusion.