Studies Made by Simulating Systole at Necropsy

Abstract

Curves of cardiac ejection at each instant of systole and curves of blood pressure at the root of the aorta were used for the precise estimation of work by integration. With these results as a target, means were sought, by simple and multiple regression equations, which would permit the estimation of work by measurements which could be made by doctors working in the clinic. Equations were derived which permit estimates of left ventricular work from the ballisto-cardiogram and peripheral blood pressure, and from peripheral blood pressure alone. In the best of these methods, the error is less than 22% of the mean young adult value for work, in 2/3 of the estimates. However, when the method is used to detect changes of heart work in any individual, the error is much less than this figure. When this method is applied to the average values for blood pressure in each decade of life, it is found that, despite the well known rise of blood pressure as age advances, the stroke work of the left ventricle diminishes as age advances.