Comparative evaluation of three elastance-resistance models of left ventricular mechanics

Three local elastance-resistance models of the left ventricular (LV) systolic function are compared starting from LV pressure and aortic flow curves measured on dogs at different afterloads. All three models, characterized by different elastance time-behaviors during relaxation, predict a decrease of the elastance and an increase of resistance for growing afterloads, in agreement with the force-length-velocity relationship at the cardiac muscle level. All models predict negative elastance values at the highest afterload supporting the presence of hyperactivation. The descriptive test is satisfied only when elastance increases during relaxation, and this supports the presence of flow-induced deactivation. In particular, the model characterized by a linear increase of elastance is clearly preferred. This is also confirmed by the results of the sensitivity analysis