Hemodynamic and adrenergic effects of combined alpha/beta-receptor blockade versus combined beta-receptor and slow channel calcium blockade in patients with ischemic heart disease.

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 2 matched groups of men suffering from ischemic heart disease. They were studied at rest supine and during ischemia-inducing exercise in the seated posture using invasive percutaneous techniques. Fourteen patients received 200 mg labetalol as a single oral dosis, 15 metoprolol (100 mg) plus nifedipine (10 mg). 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 attenuate or offset the potential adverse hemodynamic effects of beta-receptor blockade alone without loss but rather enhancement of symptomatic efficacy.