Acute effects of combined alpha/beta-adrenoceptor blockade v combined beta-receptor and slow channel calcium blockade in ischemic heart disease complicated by hypertension. Hemodynamic and adrenergic responses

Abstract

The effects of combined alpha/beta adrenoceptor blockade and of beta-receptor/slow channel calcium blockade on systemic and pulmonary hemodynamics and on adrenergic activity were compared in two matched groups of men suffering from ischemic heart disease and grade 1 to 2 hypertension. They were studied at rest supine and during ischemia-inducing exercise in the seated posture using invasive percutaneous techniques. Sixteen patients received 200 mg labetalol as a single oral doses, 15 received 100 mg metoprolol plus 10 mg nifedipine. Both regimens reduced pressures in the systemic and pulmonary circulation under all conditions. At rest, stroke volume and cardiac output slightly decreased after labetalol and increased after metoprolol/nifedipine. During exercise the changes induced by the two regimens were virtually identical; heart rates and vascular resistances were reduced, stroke volume increased, cardiac output was not significantly changed. Plasma renin activity was lowered by labetalol, unchanged by metoprolol/nifedipine. Plasma adrenaline increased after metoprolol/nifedipine only, noradrenaline with both regimens. Both combinations significantly lowered stroke work and the rate pressure product and had similar beneficial effects on the onset and the duration of angina. It is concluded that both combinations significantly reduce blood pressures and attenuate or offset the potential adverse hemodynamic effects of beta-receptor blockade alone without loss but rather enhancement of antianginal efficacy.