Myocardial constitutive laws for continuum mechanics models of the heart

Myocardial constitutive laws, for use in anatomically accurate finite element models of the heart, are presented for the passive and active mechanical properties of cardiac muscle. Biaxial testing of tissue sheets together with observations of tissue microstructure are used to define a "pole-zero" strain energy function for passive myocardium. A "fading memory" model of actively developed tension is based here on published work on the active properties of cardiac trabeculae.