A Constitutive Model of Ovine Left and Right Ventricles Biaxial Mechanical Properties

Abstract

Ventricular dysfunction is the most common cause of heart failure, which contributes significantly to mortality and morbidity in the modern society. To better understand the mechanism of the left‐ and right‐ventricle (LV and RV) failure, especially cardiac diastolic dysfunction, it is important to investigate the myocardial biaxial mechanical properties. Prior research has been focused on LV alone and has been limited to small animal models. Hence, there is a lack of study on the RV including the fundamental mechanical differences between LV and RV. Furthermore, there is a lack of data on the mechanical properties in large animal hearts (e.g., sheep) which better mimics the human heart. Our goal here was to characterize the biaxial mechanical properties of healthy sheep LV and RV tissue through constitutive modeling. In this study, a constitutive model (modified Ogden model) that is commonly used for the anisotropic hyperelastic tissue's analysis was applied to capture the biaxial mechanical behavior of the heart obtained by ex vivo experiments. The biaxial mechanical behavior was distinct between the RV and LV in both circumferential and longitudinal directions. We found that the model fit the experimental curve better for RV than LV (Figure). Furthermore, the LV and RV had different model parameters including infinitesimal shear modulus μ, nonlinearity α and anisotropy k (Table). Our results indicated that overall, the RV is stiffer in the longitudinal direction than the circumferential direction (positive k), whereas the LV is stiffer in the circumferential direction (negative k). The RV exhibited a greater degree of anisotropy than the LV, based on the magnitude of the k parameter. The RV has slightly more linear behavior (a smaller α) than the LV (a larger α). To date, this is the first study to investigate and compare biaxial mechanical behavior between LV and RV in sheep using a constitutive modeling approach. The study of the cardiac mechanics will deepen the understanding of physiological and pathological mechanisms of the myocardium. Future work will involve developing a better model for LV biaxial behavior and include more structure parameters such as collagen fiber orientation and distribution.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.