I.V. Sokolova

The author critically reviews the existing approach to the description of cardiac performance from the viewpoint of the "passive diastole" theory. This theory considers only one active phase of cardiac performance over the cardiac cycle period - systolic phase, i.e. contractile. It is assumed that blood moves through the vascular system due to systolic pressure gradient, and the heart performs as a unique one-phase hemodynamic delivery pump. It is shown that such description of cardiac performance and vascular system is contradictory and insufficient for analysis of rheogram-type biosignals of pulse repletion used to study blood movement through the vascular system and, in particular, through capillary network. This is unacceptable, because the main goal of cardiovascular system is to secure hemodynamic conditions of transcapillary exchange required for the body to live. Introduction of the second active phase of cardiac performance over the cardiac cycle period, i.e. suction phase, lays the basis for the "active diastole" theory. Heart is considered as a two-phase delivery and suction pump. The contradictions of pulse repletion biosignals interpretation are resolved with the help of the method of a two-component analysis which uses separation of arterial and venous components on the basis of a two-phase model of the general mechanism of pulse hemodynamics.