Identification of left ventricular volume regulation on the basis of the elastance concept

Left ventricular interaction with arterial load has been described in terms of the ratio (k) of effective arterial elastance (Ea) and maximal systolic elastance (Emax). Using the definition formulas for both elastances, a linear relationship between end-systolic volume (ESV) and end-diastolic volume (EDV) can be derived. The slope of this linearity equals k/(k+1), while the intercept can be identified as Vo/(k+1) where Vo is the extrapolated volume intercept of the linearized Emax-concept. Since the ESV vs EDV relationship refers to ventricular volume regulation, we have demonstrated that its characteristics can be exclusively expressed in terms of the coupling index k and the intercept Vo. We conclude that k and Vo are important determinants of the regulation of ventricular volume.