Matching of Ventricular Properties with Arterial Load Under Normal and Variably Depressed Cardiac States

Abstract

The regulation of cardiac output and venous return was diagramed classically by Guyton et al. [1] within the framework of venoventricular coupling, in which ventricular pump function was depicted by a cardiac output curve and properties of the vascular system and blood volume by the venous return curve. The equilibrium cardiac output can be obtained at the intersection between the two curves. Nearly 1 decade after, Sunagawa et al. [2] advanced Guyton’s concept further to analysis of ventriculoarterial coupling by modeling both the ventricular pump and the arterial conducting system in terms of the relationship between ventricular or arterial end-systolic pressures and stroke volume. The ventricular system is characterized by the end-systolic pressure-volume relationship. This relationship is approximately linear over a physiologic range with slope of Ees and constant volume axis intercept of Vo. The former varies in response to changes in contractility. According to this relationship. the end-systolic pressure (Pes) varies inversely with stroke volume (SV) for a given end-diastolic volume (Ved) as follows.