THERAPY AND PREVENTION HYPERTENSION Cardiovascular effects of verapamil in patients with essential hypertension

The cardiovascular effects of intravenous verapamil and 3 months of oral administration of a slow-release form of verapamil (verapamil-SR) were studied in 10 patients with mild-tomoderate essential hypertension. Intravenous verapamil reduced arterial pressure by 15% (p < .01) through a fall in total peripheral resistance of 29% (p < .01); provoked a reflexive rise in heart rate (by 19%, p < .02), cardiac output (by 74%, p < .01), and plasma catecholamines; and shifted intravascular volume toward the cardiopulmonary circulation indicating peripheral venoconstriction. Quite in contrast to the immediate effects of the intravenous drug, oral therapy with verapamil-SR for 2 to 3 months lowered arterial pressure effectively (by 15%, p < .01) by inducing vasodilation of 15% (p < .02), but without causing reflex tachycardia, activation of the sympathetic-adrenergic or renin-angiotensin systems, or volume expansion. Oral therapy with verapamil-SR preserved systemic and renal blood flow and slightly reduced cardiac mass (by 6%, p < .05) and renal vascular resistance (by 25%, p < .05). Whereas intravenous verapamil tended to depress myocardial contractility, oral verapamil-SR did not at all affect myocardial contractility or left ventricular function. These cardiovascular effects make verapamil-SR an excellent agent for long-term antihypertensive therapy. Circulation 75, No. 5, 1030-1036, 1987. THE HEMODYNAMIC HALLMARK of established essential hypertension is an increased total peripheral resistance that is caused by functional and structural changes in the arterial vascular beds. ' An antihypertensive agent should therefore be used to reduce the elevated total peripheral resistance and by such means lower arterial pressure. Apart from reducing total peripheral resistance, an ideal antihypertensive agent should also maintain systemic and regional blood flow, preserve cardiac performance, prevent fluid and salt retention, and not produce reflexive stimulation of the sympathetic adrenergic or the renin angiotensin system. Moreover, in patients with left ventricular hypertrophy and renal impairment the drug should allow left ventricular hypertrophy to regress and renal function to improve. Because calcium-entry blockers have the potential to fulfill some of the above criteria, they are evolving as attractive antihypertensive agents.` From the Department of Internal Medicine, Section on Hypertensive Diseases, Ochsner Clinic and Alton Ochsner Medical Foundation, New Orleans. Address for correspondence: Dr. Franz H. Messerli, University of Bonn, Department of Medicine, Sigmund Freud Str. 25, D-5300 Bonn, Venisburg, West Germany. Received Oct. 20, 1986; revision accepted Feb. 5, 1987. Indeed, in several therapeutic trials verapamil has been documented to control arterial hypertension effectively and safely.6' 1016 Its potential to lower blood pressure has been found to be equivalent to that of other antihypertensive agents. 16 The present study was designed to analyze the complete antihypertensive cardiovascular profile of verapamil.