A meso-scale layer-specific structural constitutive model of the mitral heart valve leaflets

Area of Science:

• Biomedical Engineering
• Materials Science
• Cardiovascular Research

Background:

• Accurate tissue-level constitutive models are crucial for understanding mitral valve (MV) disease pathophysiology.
• Existing models often lack the resolution to capture the complex fiber structures within MV leaflets.

Purpose of the Study:

• To develop a novel meso-scale structural constitutive model (MSSCM) for MV leaflet tissues.
• To incorporate detailed collagen and elastin fiber network information and their orientations.

Main Methods:

• Quantified collagen and elastin fiber structure using second harmonic generation microscopy and histology.
• Developed a meso-scale constitutive model (MSSCM) allowing collagen fiber recruitment to vary with orientation.
• Validated the model against MV small angle X-ray scattering data at the fibril level.

Main Results:

• The MSSCM predicted a consistent mean effective collagen fiber modulus of 162.72 MPa.
• Demonstrated excellent predictive capability for extra-physiological loading conditions.
• Identified anterior-posterior leaflet-specific differences in fiber orientation and tissue thickness.

Conclusions:

• The developed MSSCM accurately captures MV leaflet tissue-level function.
• The model's validation at the fibril level confirms its predictive power.
• Future use of the MSSCM will enhance computational MV models for simulations and surgical planning.