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Toward a functional model of the Mitral valve

Nariman Khaledian

Second year doctoral student, Tangram team

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Supervisors:

Dr. Marie-Odile Berger and Dr. Pierre-Frédéric Villard

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Université de Lorraine, CNRS, Inria, LORIA, Nancy, France

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Objective

  • Simulation of Mitral valve dynamic closure in healthy and pathological cases

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Leaflets

Chordae

structure

Papillary

muscles

Annulus

Mitral valve anatomy

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Objective

  • Simulation of Mitral valve dynamic closure in healthy and pathological cases
    • Contact model
    • Blood leakage detection
    • Comparably fast computation time

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Leakage

Bulging

Healthy

Blood flow direction

Opened state

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Interaction between fluid and structure

  • Mesh representation
    • Immersed Boundary (IB)
    • Arbitrary Lagrangian-Eulerian (ALE)
    • Smooth particle hydrodynamics (SPH)

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Structure domain

Fluid domain

Blood flow direction

ALE

IB

SPH

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Interaction between fluid and structure

  • Capturing contact
  • Convergence
  • Computation time

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Contact in ALE

Contact in IB

Porous medium

Leaflets

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Self-contact model

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Normal and

frictional contact

Contact map

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Model configuration

  • Case setup

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Model configuration

  • Mesh

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Model configuration

  • Constitutive model
    • 3rd order Ogden Hyperelastic material for the leaflets
    • Linear elastic for the chordae
    • Newtonian fluid with the characteristics of blood

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Results

  • Implementation of the models
    • Abaqus solver
  • Realistic simulation of Mitral valve

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Porcine Mitral valve closure

Mitral valve dynamic closure simulation

with generic geometry

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Deformation

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No chordae

Leakage

Bulging

Healthy

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Streamlines

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No chordae

Leakage

Bulging

Healthy

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Contact map

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  1. Extracting nodes with non-zero contact force
  2. Projection on a cylinder
  3. Flattening the cylinder
  4. Extracting the corresponding triangles

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One of the four leaflets

(for better visualization)

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Contributions

  • Detailed blood leakage measurement
    • We can extract the dynamic version of contact map during the closure for each patient as a video

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Healthy

Bulging

Leakage

Flattened leaflets

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Conclusion

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    • Realistic Mitral valve simulation
    • Replicating pathologies
    • Fast computation time
    • Evaluating quality of the closure

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Ongoing work

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  • Implementing anisotropy
    • Fitting experimental data to a holzapfel-Gasser-Ogden anisotropic hyperelastic material

Material direction

Experimental data (Amini et al)

Extracting strain energy coefficients by fitting the experimental data

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Ongoing work

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  • Implementing real geometry
    • Ongoing work

Real geometry extracted from medical imaging

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Future targets

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  • Investigating the implementation of deep learning for identifying geometry properties required by better simulation
  • Make our model patient-based by focusing on realistic geometry based on segmentation