[Intravenous labetalol in normotensive coronary patients. Effects on hemodynamics and myocardial metabolism].

The haemodynamic and myocardial metabolic effects of intravenous Labetalol were studied in 7 normotensive coronary patients with at least one significant stenosis on the left anterior descending artery. The study consisted of 5 successive observation periods: basal (I); during atrial pacing at the theoretical maximal heart rate or when anginal pain occurred (II); return to basal conditions (III); 20 minutes after an injection of 1.5 mg/kg of Labetalol over 3 minutes into the pulmonary artery (IV); during repeat atrial pacing at the rate achieved during phase II (V). There was no significant difference between phases I and III except for a slightly faster heart rate in phase III. The effects of Labetalol were assessed by comparing the results during phases III and IV between phases II and V and by analysing the variations between phases I, II, IV and V. In comparison with basal conditions (phase III), Labetalol (phase IV) induced a slight decrease in cardiac output (p less than 0.05), a decrease in aortic pressure and systemic arterial resistances (p less than 0.01) and of the double product. Coronary sinus flow did not change but myocardial oxygen consumption fell by an average of 11% (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)