Modelling cardiac mechanical properties in three dimensions

The central problem in modelling the multi-dimensional mechanics of the hea rt is in identifying functional forms and parameters of the constitutive eq uations, which describe tile material properties of the resting and active, normal and diseased myocardium. The constitutive properties of myocardium are three dimensional, anisotropic, nonlinear and time dependent. Formulati ng useful constitutive laws requires a combination of multi-axial tissue te sting in. vitro, microstructural modelling based on quantitative morphology , statistical parameter estimation, and validation with measurements from i ntact hearts. Recent models capture some important properties of health;yr and diseased myocardium including: the nonlinear interactions between the r esponses to different loading patterns; the influence of the laminar myofib re sheet architecture; the effects of transverse stresses developed by the myocytes; and the relationship between collagen fibre architecture and mech anical properties in healing scar tissue after myocardial infarction.