Left-ventricular dynamic model based on constant ejection flow periods

A simulation model that is based on findings of constant ejection flow experiments is presented. This model is tested on measured pressure and volume data. The results show that when the model is fitted on one single beat, left ventricular pressure can satisfactorily be described by a three-element model without deactivation. When isovolumic pressure has to be described by the model as well, introduction of deactivation is necessary. The quality of the model was further tested by fitting it to two beats with different ejection parameters. Deactivation again was necessary for a good fit. Only with a deactivation effect in the model, the component values found are close to the normal range found with constant-flow-period experiments in the rabbit left ventricles. From the simulation results it is concluded that (at least for constant ejection flow periods) elastance, resistance, series-elastance, and deactivation effects all are necessary in describing (and predicting) left ventricular pressure.