CLINICAL STUDIES ON THE CARDIAC PERFORMANCE BY MEANS OF TRANSSEPTAL LEFT HEART CATHETERIZATION. THE ACUTE EFFECTS OF DIGITALIS ON LEFT VENTRICULAR FUNCTION IN PATIENTS WITH VALVULAR STENOSIS.

Abstract

In 13 patients with various heart diseases, the acute effects of digitalis on the left ventricular performance were studied by the transseptal left heart catheterization using external monitoring of radioisotope dilution and following results were obtained:(1) In patients with mitral stenosis, in whom heart rate was not altered after digitalization, the cardiac output did not increase significantly presumably because of mitral obstruction, while the left ventricular end-diastolic pressure and volume decreased. This may be interpreted as a result of positive inotropic effect of digitalis.(2) In patients with mitral stenosis, in whom heart rate was decreased, cardiac output increased significantly in association with an increase of left ventricular end-diastolic pressure and volume. This may be interpreted as a result of negative chronotropic effect of digitalis; that is increased left ventricular filling secondary to increased diastolic filling period.(3) In patints with aortic stenosis, left ventricular systolic and enddiastolic pressure and volume and systolic tension increased with decrease of left ventricular circumferential shortening rate. This may be interpreted as a result of increased resistance at the aortic ostium and increased contractility of the left ventricle.These effects of digitalis were compared with those of theophylline ethylenediamine and induced hypervolemia. It is concluded that the modes of action of digitalis on left ventricular function are multiple depending on the state of the heart, and that the effects may generally be expressed as the summation of positive inotropic and negative chronotropic effect.