Study of biaxial mechanical properties of the passive pig heart: material characterisation and categorisation of regional differences

This study quantifies the regional biaxial mechanical properties of passive porcine myocardium to support more accurate constitutive modeling and computational heart simulations. Tissue specimens were harvested from three heart regions—left ventricle (LV), right ventricle (RV), and mid-wall/interventricular septum (MDW)—and tested under biaxial tension. The results demonstrate that passive myocardium exhibits nonlinear, anisotropic behavior and that mechanical properties vary by region, challenging the common modeling assumption that ventricular myocardium is homogeneous. Experimental stress–strain data were fit to two hyperelastic constitutive models (Fung and Choi-Vito), and regional parameter sets and anisotropy indices were reported. The work provides region-specific material parameters intended for use in finite element models of cardiac mechanics and disease simulations (e.g., myocardial infarction).