A constitutive relation for passive right-ventricular free wall myocardium

Area of Science:

• Biomedical Engineering
• Cardiovascular Mechanics
• Materials Science

Background:

• The passive mechanical properties of the right ventricle free wall myocardium are crucial for understanding cardiac function.
• Previous models often simplify the complex, anisotropic nature of myocardial tissue.

Purpose of the Study:

• To characterize the passive biaxial mechanical properties of the right ventricle free wall myocardium.
• To apply and validate the pseudostrain energy function for myocardial tissue modeling.

Main Methods:

• Utilized the pseudostrain energy function developed by Humphrey et al.
• Assumed myocardium to be incompressible, pseudoelastic, and transversely isotropic.
• Accounted for transmural variations in fiber orientation using nonlinear regression to determine material constants for sinus and conus regions.

Main Results:

• The pseudostrain energy function effectively modeled the biaxial mechanical data with high accuracy (r2 > 0.99).
• Transmural variations in Cauchy stresses and in-plane shear stress were found to be minimal.
• Quantitative differences were observed when compared to left ventricle data, but qualitative similarities in mechanical behavior were noted.

Conclusions:

• The pseudostrain energy function provides a robust framework for characterizing right ventricle free wall myocardium passive mechanics.
• Myocardial tissue exhibits complex passive mechanical behavior that can be effectively modeled by advanced constitutive laws.
• Further research comparing ventricular mechanics can elucidate functional differences between cardiac chambers.