Effects of Beta-Adrenergic Blockade (Propranolol) on Left Ventricular Hemodynamics and the Electrocardiogram During Exercise-Induced Angina Pectoris

Abstract

The effects of intravenous propranolol were studied in nine patients with ischemic heart disease during cardiac catheterization. Values were obtained at rest and during exercise before and after propranolol. A work load known to produce angina and significant ST depression was selected. Pressures were monitored during exercise and correlated with electrocardiographic changes and appearance of angina. At rest and exercise, propranolol caused a decrease in heart rate, cardiac output, mean systolic ejection rate, stroke volume, left ventricular systolic pressure, first derivative, and work. Left ventricular end-diastolic pressure did not significantly change. Angina, which developed in all nine patients during control exercise, did not appear in four after propranolol, while ECG abnormalities were less marked in all cases. Comparison of exercise responses following propranolol in angina-free patients (four) with those developing angina (five) disclosed a more pronounced negative inotropism in the angina-free group. It is concluded that propranolol is beneficial in angina. Improvement derives primarily from suppression of positive chronotropic and inotropic responses, which are major determinants of myocardial oxygen consumption.