Labetalol infusion for the treatment of hepertension in acute myocardial infarction

The haemodynamic effects of labetalol infusion (mean dose 1mg/min) were measured in seven patients with sustained hypertensioncomplicating acute myocardial infarction. Four of the patientshad severe left ventricular failure. A fall in both systolic(mean 185 to 126 mm Hg) and diastolic (mean 87 to 68 mm Hg)blood pressure occurred in all patients. Cardiac index fellfrom 2.5 to 2.0 l/min/m²; systemic vascular resistance was notaffected. Heart rate slowed from 83 to 70 beats/ min. Labetalollowered pulmonary artery pressure in the patients with leftventricular failure. Labetalol is an effective antihypertensive agent in patientswith acute myocardial infarction and our results suggest itis safe provided cardiac output is within or near the normalrange. It seems not to be contraindicated in the presence ofpulmonary oedema. The effects imply that myocardial oxygen requirementswill be reduced. The implications for limitation of infarctsize in patients presenting early after acute infarction shouldbe determined.