Left ventricular end-systolic pressure-volume relationships as a measure of ventricular performance.

The extent to which conclusions about myocardial performance may be drawn from end-systolic pressure-volume relations was investigated. Left ventricular isovolumetric and end-systolic pressure-volume relationships were measured in the rat, under acute impairment of contractility (hexobarbital), at chronic pressure overload (spontaneously hypertensive rats), and at chronic volume overload (aorto-caval shunt). Our results confirm the classic conception of Otto Frank where the curves of the isovolumetric maxima and the curves of the end-systolic pressure-volume relations follow separate courses. Acute alterations in contractility can be detected from shifts in the end-systolic pressure-volume relations. In chronic pressure or volume overloaded hearts the end-systolic pressure-volume relations do not render conclusions about ventricular or myocardial performance since in chronically altered hearts, the course of the end-systolic pressure-volume relations is primarily influenced by geometric factors.