Regulation of the Degree of Emptying of the Left Ventricle by the Force of Ventricular Contraction

Results are presented which indicate that left ventricular end-systolic volume is determined by the force-length relationship of the ventricular muscle at the end of systole. In other words the muscle continues to shorten until it meets a certain force the magnitude of which depends on the length of the musclc fibers at that time; when it meets this force it shortens no further. Since the end-systolic volume is an important determinant of stroke volume the suggestion is made that future studies should be directed toward measuring the effect of various influences on the force-length relationship and the modulus of elasticity of the end of systole in addition to studying the effects on the end-diastolic volume.