A comparison of the effects of combined or separate alpha- and beta-blockade in the treatment of hypertension in the acute stage of myocardial infarction.
We have assessed the benefit of separate or combined alpha- and beta-receptor blockade in the treatment of 33 patients suffering from acute (less than 48 hr) myocardial infarction complicated by sustained (greater than 6 hr) systolic hypertension (systolic blood pressure greater than 150 mm Hg). Eight patients have been treated with metoprolol, 7 with phentolamine and 18 with labetalol. We evaluated the effects of these drugs on hemodynamics and arterial and mixed venous blood gases. The patients were divided into two groups on the basis of the pulmonary wedge pressure. The first group had a pressure greater than 15 mm Hg. It included 9 patients treated with labetalol (1.8 mg/min for 1 hr) and 7 others with phentolamine (0.6 mg/min for 1 hr). The wedge pressure in the second group was less than 13 mm Hg. Nine patients in this group had been treated with labetalol (2.1 mg/min for 1 hr) and 8 others with metoprolol (0.2 mg/kg in 15 min). Labetalol normalized the blood pressure in both groups within 1 hr as did phentolamine. Metoprolol did not significantly reduce either the systolic or the diastolic pressures. The high wedge pressures in the first group were reduced by both labetalol and phentolamine. The cardiac index was increased following phentolamine administration while it was reduced by labetalol. In the group with low wedge pressure, labetalol and metoprolol induced a slight but significant reduction in cardiac index but the pulmonary wedge pressures were significantly increased for metoprolol only. The rate-pressure product was very significantly decreased by labetalol and metoprolol but not by phentolamine. The emergency treatment of systemic hypertension occurring in the setting of acute myocardial infarction would thus appear to be best achieved by combined alpha- and beta-blockade rather than with either pure alpha- or pure beta-blockade. Phentolamine, however, would be a good drug in the presence of a reduced cardiac index.
Renard
M
M
Jacobs
P
P
Liebens
I
I
Abou Hamdam
B
B
Bernard
R
R
D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002245:Carbon Dioxide / Q000097:blood; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006973:Hypertension / Q000097:blood / Q000150:complications / Q000188:drug therapy* / Q000503:physiopathology; D007263:Infusions, Parenteral; D007741:Labetalol / Q000008:administration & dosage / Q000627:therapeutic use*; D008790:Metoprolol / Q000008:administration & dosage / Q000627:therapeutic use*; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000503:physiopathology; D010100:Oxygen / Q000097:blood; D010646:Phentolamine / Q000008:administration & dosage / Q000627:therapeutic use*
D002245:Carbon Dioxide; D008790:Metoprolol; D007741:Labetalol; D010100:Oxygen; D010646:Phentolamine