A New Dissipation Function to Model the Rate-Dependent Mechanical Behavior of Semilunar Valve Leaflets

Area of Science:

• Biomechanics
• Biomaterials Science
• Cardiovascular Engineering

Background:

• Semilunar heart valves exhibit complex rate-dependent mechanical behavior.
• Existing models often struggle to accurately capture these dynamic responses.
• Experimental data reveal distinct stiffening and asymptotic effects with varying deformation rates.

Purpose of the Study:

• To develop a novel dissipation function (Wv) for modeling the rate-dependent mechanical behavior of heart valves.
• To integrate this function with hyperelastic models to improve accuracy.
• To validate the model against experimental biaxial deformation data.

Main Methods:

• Devised a new dissipation function (Wv) based on experimental data from aortic and pulmonary valve specimens.
• Incorporated Wv into a hyperelastic strain energy function (We), explicitly including deformation rate.
• Analyzed biaxial deformation data across a 10,000-fold range of deformation rates.

Main Results:

• The proposed Wv function successfully captured the observed rate-dependent stiffening and asymptotic effects.
• The integrated model demonstrated excellent agreement with experimentally obtained stress-stretch (σ-λ) curves.
• The model accurately represents the mechanical response of heart valves across a wide range of deformation rates.

Conclusions:

• The new dissipation function (Wv) provides an effective method for modeling rate-dependent heart valve mechanics.
• The model's accuracy in fitting experimental data supports its clinical and research applicability.
• This approach is recommended for soft tissues exhibiting similar rate-dependent mechanical properties.