A Viscoelastic Model for Human Myocardium

TL;DR

This paper introduces a fractional nonlinear anisotropic viscoelastic model for human myocardium that better captures experimental data than traditional hyperelastic models, enhancing biomechanical understanding and potential clinical applications.

Contribution

The paper presents a novel fractional viscoelastic constitutive model for human myocardium, incorporating experimental data and hierarchical tissue structure, improving accuracy over existing hyperelastic models.

Findings

Model replicates biaxial stretch, shear, and stress relaxation with ~7.65% error.

Outperforms hyperelastic models with ~25% error.

Demonstrates model sensitivity, fidelity, and applicability to various loading modes.

Abstract

Understanding the biomechanics of the heart in health and disease plays an important role in the diagnosis and treatment of heart failure. The use of computational biomechanical models for therapy assessment is paving the way for personalized treatment, and relies on accurate constitutive equations mapping strain to stress. Current state-of-the art constitutive equations account for the nonlinear anisotropic stress-strain response of cardiac muscle using hyperelasticity theory. While providing a solid foundation for understanding the biomechanics of heart tissue, most current laws neglect viscoelastic phenomena observed experimentally. Utilizing experimental data from human myocardium and knowledge of the hierarchical structure of heart muscle, we present a fractional nonlinear anisotropic viscoelastic constitutive model. The model is shown to replicate biaxial stretch, triaxial cyclic shear and triaxial stress relaxation experiments (mean error ~7.65%), showing improvements compared to its hyperelastic (mean error ~25%) counterparts. Model sensitivity, fidelity and parameter uniqueness are demonstrated. The model is also compared to rate-dependent biaxial stretch as well as different modes of biaxial stretch, illustrating extensibility of the model to a range of loading phenomena.