MODELING THE MECHANICAL-PROPERTIES OF CARDIAC-MUSCLE

A model of passive and active cardiac muscle mechanics is presented, s uitable for use in continuum mechanics models of the whole heart. The model is based on an extensive review of experimental data from a vari ety of preparations (intact trabeculae, skinned fibres and myofibrils) and species (mainly rat and ferret) at temperatures from 20 to 27 deg rees C. Experimental tests include isometric tension development, isot onic loading, quick-release/restretch, length step and sinusoidal pert urbations. We show that all of these experiments can be interpreted wi th a four state variable model which includes (i) the passive elastici ty of myocardial tissue, (ii) the rapid binding of Ca2+ to troponin C and its slower tension-dependent release, (iii) the kinetics of tropom yosin movement and availability of crossbridge binding sites and the l ength dependence of this process and (iv) the kinetics of crossbridge tension development under perturbations of myofilament length. (C) 199 8 Elsevier Science Ltd. All rights reserved.