13 Feb Inside the Hierarchical VVUQ Approach for TAVI Heart Valves

Step-by-Step to Simulation Excellence

Developing a reliable computational model for a complex medical device like the TAVI heart valve is no small feat. The interplay of structural mechanics, material properties, and fluid dynamics creates a web of interdependencies that must be accurately captured. At 4RealSim, we tackled this challenge using a hierarchical Verification, Validation, and Uncertainty Quantification (VVUQ) methodology.

This tiered approach allowed us to build our FSI model for the Sapien 3 TAVI device from the ground up, addressing challenges at every level of complexity.

The Four Tiers of Hierarchical Modeling

1 Material Models
At the foundation of any simulation lies accurate material modeling. For the Sapien 3 TAVI device, we calibrated models for each component based on literature and technical documentation:

– The stent frame uses a Johnson-Cook plasticity model to capture its behavior during expansion and recoil.
– The leaflets employ an anisotropic hyperelasticity model to replicate the unique properties of bovine pericardial tissue.
– The skirt and balloon materials are modeled as isotropic hyperelastic polymers.

2 Component Models
Once material properties were established, we modeled individual device components like the stent frame, leaflets, and skirt. These models were then subjected to rigorous verification tests to ensure their mechanical responses aligned with known experimental results.

3 Device Models
The fully assembled TAVI device model was tested for its structural and functional performance. This included simulating the balloon-based deployment process and assessing elastic recoil under physiological conditions.

4 FSI Integration
Finally, the device was placed in a virtual in-vitro flow chamber to evaluate its hydrodynamic performance. Fluid-Structure Interaction was simulated using Smoothed-Particle Hydrodynamics (SPH) techniques, focusing on key metrics like pressure gradients and regurgitation rates.

Overcoming Challenges with VVUQ

The VVUQ framework ensured that discrepancies between simulation and experimental data were systematically identified and resolved. For example:
– Stent Frame Validation: The model achieved excellent agreement with MicroCT measurements of the stent frame’s expansion.
– Leaflet Behavior: Initial discrepancies in leaflet deformation were traced to uncertainties in material properties and dimensions. Refinements improved accuracy significantly.

Explore the Methodology in Our Webinar

Want to see how this rigorous, multi-tiered approach delivers reliable simulation results? Join us for an in-depth webinar:
👉 Credibility Assessment of a TAVI Heart-Valve FSI Model
Learn how hierarchical VVUQ modeling can transform medical device development and beyond.