Time Course of Left Ventricular Pressure-Volume Relationship under Various Enddiastolic Volume

A variable, e (t) =p (t) /v (t), is proposed for formulating the ventricular pumping of blood, as a concept of the reciprocal of ventricular compliance, where t=time, p (t) =time course of the intraventricular pressure and v (t) =that of the intraventricular volume. For actual computation, e (t) =p (t) /v (o) -∫toi (t) dt where v (o) =v (t) at t=o or enddiastolic volume and i (t) =aortic blood flow. v (o) = (1-ρ) -1•vs, where ρ=residual volume ratio measured by a thermodilution method and vs=stroke volume or integral of i (t) in the cardiac cycle. e (t) is calculated of areflexive left ventricles of dogs under various v (o) controlled by occlusion of the vena cava. In spite of conspicuous changes of p (t), i (t) and v (t), e (t) has ap-proximately unchanged time course and magnitude in a wide range of v (o). A model of ventricular pumping is presented with e (t).