Verification of a Fluid-Structure Interaction Model for Aortic Stenosis Through Comparison With In Vitro Experiments

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Computational Fluid Dynamics

Background:

• Current aortic stenosis (AS) severity assessment relies on rest pressure gradients, which are flow-dependent and may underestimate disease severity.
• Resting measurements do not capture valvular dynamics during higher flow rates, such as exercise, complicating clinical decisions.
• Patient-specific Fluid-Structure Interaction (FSI) modeling offers a non-invasive approach to simulate valve dynamics under various flow conditions, independent of ventricular pressure.

Purpose of the Study:

• To experimentally verify a patient-specific aortic stenosis FSI model using realistic aortic valve geometries, including calcifications.
• To assess the model's accuracy across a range of flow conditions, from rest to exercise.
• To evaluate the potential of FSI modeling as a complementary tool for AS severity assessment and clinical decision support.

Main Methods:

• In vitro experiments were conducted using a mock-loop circulatory system with patient-specific silicone rubber aortic valve models (calcified and non-calcified).
• Fluid-Structure Interaction (FSI) simulations were performed to replicate the experimental conditions.
• Comparison of simulated and experimental results for transvalvular flow and aortic valve area (AVA) was conducted.

Main Results:

• Good agreement was observed between FSI simulations and experimental data for the non-calcified valve, with average errors of 5% for mean transvalvular flow and 10% for AVA.
• Discrepancies were larger for the calcified valve (average errors of 8% for flow and 7% for AVA) due to the complexity of calcifications.
• The study demonstrated the feasibility of FSI modeling for assessing AS severity.

Conclusions:

• Patient-specific FSI modeling is a feasible non-invasive method to assess aortic stenosis severity across different flow conditions.
• Further research is needed to refine methods for estimating leaflet material properties and pre-stress for clinical implementation.
• Model verification with broader in vitro data and validation with clinical data are essential next steps for widespread adoption.