A poroelastic immersed finite element framework for modelling cardiac perfusion and fluid-structure interaction

Area of Science:

• Computational mechanics
• Biomedical engineering
• Cardiovascular modeling

Background:

• Cardiac perfusion modeling often uses poroelasticity for myocardium, treating it as a saturated porous medium.
• Previous models either simplified fluid-structure interaction or neglected intracardiac blood flow in poroelastic analyses.
• A unified framework is needed to couple myocardium poroelasticity with chamber blood flow.

Purpose of the Study:

• To present a poroelastic immersed finite element framework for left ventricular (LV) dynamics.
• To model a three-phase poroelastic system including pore blood, skeleton, and chamber fluid.
• To compare poroelastic LV models with hyperelastic models and analyze the impact of perfusion.

Main Methods:

• Developed a poroelastic immersed finite element framework for LV simulation.
• Utilized a three-phase poroelastic system (pore blood, skeleton, chamber fluid).
• Benchmarked the framework with cubic geometries and compared isotropic/anisotropic skeleton models.
• Simulated 3D LV dynamics using the Holzapfel-Ogden law for the myocardium.

Main Results:

• The poroelastic LV model exhibits distinct behavior compared to hyperelastic models.
• Accounting for perfusion leads to a smaller diastolic chamber volume.
• Observed a wall-stiffening effect under perfusion, consistent with previous findings.
• Differences in systolic function, particularly fiber strain, were minor.

Conclusions:

• The developed poroelastic framework accurately models LV dynamics and perfusion.
• Poroelasticity significantly influences diastolic LV mechanics, particularly chamber volume and wall stiffness.
• The model provides a more comprehensive understanding of cardiac mechanics by integrating fluid-structure interaction and tissue poroelasticity.