A biphasic, anisotropic model of the aortic wall

Area of Science:

• Biomechanics
• Biomedical Engineering
• Cardiovascular Research

Background:

• The mechanical properties of the aortic wall are crucial for understanding cardiovascular function and disease.
• Existing models often simplify the complex anisotropic and biphasic nature of vascular tissue.
• Accurate modeling requires considering factors like intraluminal pressure and tissue hydration.

Purpose of the Study:

• To develop and validate a biphasic, anisotropic elastic model of the aortic wall.
• To compare model predictions with experimental measurements of aortic dimensions and hydraulic conductivity under varying pressures.
• To investigate the relationship between tissue dilation and hydraulic conductivity.

Main Methods:

• Development of a biphasic, anisotropic elastic model for the aortic wall.
• Comparison of model-predicted vessel wall radii, thickness, and hydraulic conductivity with literature data.
• Analysis of constant vs. strain-dependent wall modulus requirements at different intraluminal pressures.

Main Results:

• The model accurately predicts aortic wall behavior, particularly with a strain-dependent modulus above 60 mmHg.
• Tangential elastic modulus is approximately 20 times greater than the radial modulus in both bovine and rabbit aorta.
• Aortic volume and specific hydraulic conductivity show relative independence from perfusion pressure, aligning with experimental findings.

Conclusions:

• The developed model provides a robust framework for simulating aortic wall mechanics.
• The findings highlight the anisotropic nature of the aortic wall and the pressure-dependent changes in its elastic properties.
• A positive parameter M is identified, correcting a previous error in the literature regarding hydraulic conductivity and tissue dilation.