Cardiac Decompensation in Dogs Subjected to Chronic Congestive Heart Failure

Abstract

Right ventricular isometric systolic tension (1ST) was measured with a strain gauge lever system prior to and 25-30 days following surgically induced tricuspid insufficiency and pulmonary stenosis (TI and PS), each animal serving as its own control. Right ventricular pressure, heart rate, and in some experiments electrocardiogram, right atrial and pulmonary arterial pressures were measured. 1ST was shown to be markedly reduced (53.7%) in heart failure dogs with TI and PS. This dcerease in 1ST was accompanied by a 26.8% increment in heart rate and a decrease in the rate of myocardial relaxation. It was concluded that the law of Laplace may determine the limit of cardiac function obtained through the Starling effect and when this compensatory mechanism is encroached upon to the degree observed in this study, decompensation will occur. These and other factors were briefly discussed in relation to cardiac reserve and decompensation. © 1967, International Heart Journal Association. All rights reserved.