Effects of propranolol on left ventricular function in normal men

Abstract

In this study we assessed the effects of β-adrenergic blockade on cardiac function during exercise. First-pass radionuclide angiography was used to measure left ventricular ejection fraction (LVEF), cardiac output (CO), end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV) and pulmonary transit time (PTT) in 12 normal young men. Studies were first performed at rest and during upright bicycle exercise after 2 days of oral administration of propranolol 320 mg/day. A minimum of 48 hours after cessation of propranolol, hemodynamic measurements were made at rest, during exercise at the same heart rate achieved on propranolol and during exercise at the same work load achieved on propranolol. Control studies showed a progressive increase in LVEF, SV and CO at increasing levels of exercise and a progressive decrease in ESV and PTT. After propranolol administration heart rate, LVEF and CO were decreased at rest (p=0.0001 for all values). During exercise, heart rate, systolic blood pressure, LVEF and CO were significantly lower (p = 0.0001 for all values), while ESV and PTT were significantly increased (p<0.0001 and p = 0.002, respectively) compared with control exercise at the same work load. Compared with control exercise at comparable heart rates but different work loads, hemodynamic measurements were not significantly different on propranolol. These data suggest that the effects of propranolol on rest and exercise hemodynamics in healthy adults are primarily due to alterations in heart rate.