 Ventricular elastance

Time-dependent elastance models the pressure generated by a cardiac ventricle at its current stressed volume. The reference $V_0$ is its zero-pressure volume. The inverse of elastance is compliance at fixed time. Rising elastance increases pressure without volume change during isovolumetric contraction; an approximately constant systolic value $E_S$ gives compliance $C_s=1/E_S$ during a simplified ejection stage.