A transverse isotropic viscoelastic constitutive model for aortic valve tissue

Area of Science:

• Biomechanics
• Materials Science
• Cardiovascular Research

Background:

• Aortic valve (AV) mechanical properties exhibit directional dependency due to collagen fiber alignment.
• Understanding the anisotropic and rate-dependent behavior of the AV is crucial for diagnosing and treating cardiovascular diseases.

Purpose of the Study:

• To develop and validate a novel anisotropic viscoelastic model for the aortic valve.
• To characterize the shear-thinning behavior of AV tissue under varying deformation rates.

Main Methods:

• Developed a transverse isotropic anisotropic viscoelastic model incorporating viscous dissipative effects.
• Determined model parameters by fitting to uniaxial tensile tests of porcine AV specimens at various deformation rates.
• Predicted and validated stress-deformation curves under physiological conditions.

Main Results:

• The model demonstrated an excellent fit to experimental data across all tested deformation rates.
• Established a nonlinear relationship between viscosity and deformation rate, indicating shear-thinning behavior.
• Predicted stress-deformation curves showed excellent agreement with experimental validation data.

Conclusions:

• The developed anisotropic viscoelastic model accurately captures the complex mechanical behavior of the aortic valve.
• The identified shear-thinning characteristic is a key feature of AV tissue response to deformation.
• The model provides a valuable tool for predicting AV tissue mechanics and can be adapted for other collagenous soft tissues.