Beta-Adrenoceptor Blockers, Calcium Antagonists and Combined Alpha-Beta-Receptor Blockade in Coronary Heart Disease: Haemodynamic Profiles

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Both beta-receptor blockers and calcium antagonists reduce angina and increase exercise tolerance in ischemic heart disease. Similar beneficial effects can be achieved a balanced blockade of both beta- and alpha-1-adrenoceptors. However, the underlying mechanisms differ profoundly. The hemodynamic responses at rest and during exercise elicited by the three regimens was evaluated in 3 matched groups of men with ischemic heart disease, mean age for the groups 55, 56 and 58 years. They were studied invasively at rest and during exercise, before and after single oral doses of metoprolol (100 mg), labetalol (200 mg) and nifedipine (10 mg). Metoprolol reduced mean arterial pressures, heart rate and cardiac output. Systemic vascular resistance and left ventricular filling pressure increased. Nifedipine treatment resulted under all conditions in a distinct decrease of systemic vascular resistance and arterial pressures, and a slight increase of heart rate and cardiac output. Left ventricular filling pressure was significantly reduced, the more the higher the initial level. The effect of labetalol was similar to that of nifedipine; however, cardiac output was unchanged, heart rate was slightly reduced. Left ventricular filling pressure was significantly lower.