Evaluation of the alpha and beta blocking effects of intravenous labetalol on left ventricular function in coronary artery disease.

Intravenous labetalol was evaluated in 10 patients with stable angina without heart failure. Mean dose was 1.75 mg/kg (range 1.5-2 mg/kg). Measurements were taken within one minute after the injection, and at 1, 5 and 15 minutes thereafter. Labetalol significantly decreased blood pressure and increased heart rate. Peak aortic flow velocity increased only significantly at 1 minute; dP/dt+ max. was significantly decreased during all the measurements. Left ventricular end diastolic pressure did not change. Thus in patients without failure left ventricular function remained stable despite the negative inotropic effects of labetalol.