Left Ventricular Performance

THLIE pharmacologic effects of digitalis preparations on the circulatory system have been the subject of numerous investigations in both animals and man. Recently, studies in dogs 1 and man,2' 3as well as experimental work on the proteins of the contractile element of heart muscle,4 have demonstrated that digitalis directly augments the force of myocardial contraction. Most investigations in man, however, have dealt with measurements of flow and pressure changes in the pulmonary circulation,5-'2 and only a few have assessed left ventricular function directly.2' 3 The following study was undertaken in order to evaluate the effects of acute digitalization on some hemodynamic measures of human left ventricular performance during cardiac catheterization. They include not only standard pressure-flow phenomena but also several rate-dependent aspects of function such as mean ventricular stroke power, the duration and the mean rate of systolic ejection, and the rate of pressure rise in the left ventricle.