A biphasic modeling framework for arterial compressibility under steady axisymmetric deformation

Area of Science:

• Biomechanics
• Fluid Dynamics
• Materials Science

Background:

• Arterial walls traditionally modeled as incompressible due to high water content.
• Recent studies indicate significant arterial compressibility under varying loads.
• The mechanical basis for this observed compressibility remains unclear.

Purpose of the Study:

• Develop a biphasic model for arterial mechanics.
• Investigate the role of interstitial fluid transfer in arterial compressibility.
• Clarify the mechanical origins and implications of arterial volumetric changes.

Main Methods:

• Modeled arterial wall as a saturated biphasic material (solid skeleton + interstitial fluid).
• Solid skeleton treated as anisotropic, hyperelastic material; fluid flow governed by Darcy's law.
• Reduced nonlinear equilibrium to a 1D radial boundary-value problem solved via finite element method.

Main Results:

• Model predictions for deformations and volumetric changes align with experimental data (within 2% deviation).
• Interstitial fluid pressure drives volumetric expansion, inducing radial tensile stresses in the solid skeleton.
• Demonstrated consistency between biphasic model predictions and observed arterial behavior.

Conclusions:

• Apparent arterial compressibility arises from interstitial fluid transfer.
• Biphasic modeling offers a mechanically interpretable framework for fluid-solid interactions in arteries.
• Revealed implications of fluid-solid interactions not evident from deformation alone.