The pressure-volume relation of left ventricles during isobaric contractions.

Abstract

By extending the eigen stress model and Starling's law of the heart, a viscoelastic mechanical model was proposed for analysing the deformation of ejecting ventricles under constant ejection pressures. The model consisted of time-varying elements (i.e., elastic and contractile element) with a parallel viscous element. Based on this model, a differential equation (was obtained), which expressed the pressure-volume relation of left ventricles. It was found that the viscous coefficient had no dependency on the end-diastolic volume. Numerical results from experiments using 4 dogs showed that the viscous coefficient became a constant value independent of time during isobaric contractions. This model was able to predict the left ventricular volume during isobaric contractions.