Effect of afterload on the time-course of left ventricular systolic elastance

An elastance-resistance model of the left ventricle is used in conjunction with previously measured left ventricular pressure and outflow to derive elastances under three different loading conditions: control, hypertension, and hypotension. Using various times and time ratios of the elastance curves, it is shown that for decreasing load, elastance increases at a faster rate. This is also shown by normalizing the elastance curves with respect to the maximum elastance (E _max) and the time to E_max. Possible explanations for these observations are given