Haemodynamic Effects of Β‐receptor Blocking Agents and Digitalis in Ischaemic Coronary Heart Disease With Angina Pectoris

Abstract

Abstract. The haemodynamic effects of β‐receptor blocking agents (propranolol and pindolol) alone and in combination with digitalis have been studied at rest and during exercise in 20 patients with coronary heart disease and angina pectoris. Right heart catheterization was performed and cardiac output was determined by the indicator‐dilution technique. β‐blockade induced at rest a significant fall in heart rate, all other variables studied being fairly unchanged. During exercise the cardiac output and stroke volume were lower than before β‐blockade, while the BP in the right ventricle, pulmonary artery and pulmonary wedged position rose. Propranolol gave a slightly greater increase in pulmonary artery wedged pressure compared to pindolol, but no significant differences concerning the other variables studied. After administration of digitalis together with a β‐blocking agent the systolic and end‐diastolic pressures of the right ventricle as well as the pulmonary artery wedged pressure during exercise were significantly lower than after β‐blockade alone. Cardiac output, stroke volume and calculated left ventricular work index were all significantly higher, while the product of heart rate and systolic BP was unchanged. These findings indicate that digitalis eliminates the negative inotropic effect of a β‐blocking agent but leaves the negative chronotropic effect unchanged. It is suggested that, when a β‐blocking agent is used in the treatment of angina pectoris, digitalization seems to be indicated when cardiac failure is likely to appear.