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Evaluation of the Haemodynamic Behaviour of Stenosed Aortic Heart Valves Using Fluid Structure Interaction Modelling
Lindi Grobler Kock1, Ryno Laubscher1, Johan van der Merwe1
1Institute of Biomedical Engineering, Department of Mechanical and Mechatronic Engineering, Stellenbosch University, Stellenbosch, South Africa.
Summary
Rheumatic aortic stenosis (RAS) imposes a higher workload on the left ventricle than calcific aortic stenosis (CAS). Clinical methods for estimating transvalvular pressure gradients (TPG) are insensitive to stenosis type and severity.
Area of Science:
- Cardiovascular Medicine
- Biomedical Engineering
- Computational Fluid Dynamics
Background:
- Aortic stenosis (AS) is a valvular heart disease defined by aortic valve (AV) narrowing.
- Calcific AS (CAS) and rheumatic AS (RAS) present distinct valve morphologies.
- Understanding hemodynamic differences between CAS and RAS is crucial for patient management.
Purpose of the Study:
- To analyze the hemodynamic environment of calcific and rheumatic aortic valves (AV) using 3D Fluid-Structure Interaction (FSI) modeling.
- To compare the transvalvular pressure gradients (TPG) and left ventricular workload between CAS and RAS of varying severities.
- To evaluate the accuracy of the simplified Bernoulli approximation for clinical TPG estimation in different AS types.
Main Methods:
- Utilized 3D Fluid-Structure Interaction (FSI) modeling to simulate blood flow through generic calcific and rheumatic aortic valves (AV).
- Analyzed hemodynamic parameters including transvalvular pressure gradients (TPG) and velocity magnitudes for moderate, severe, and very severe AS.
- Compared ground-truth TPG from FSI simulations with clinical estimations derived from the simplified Bernoulli approximation.
Main Results:
- Rheumatic AS cases exhibited higher TPG and velocity magnitudes compared to calcific AS of equivalent severity.
- The left ventricle's additional workload was significantly higher in rheumatic AS (5.6% to 58.3% increase) versus calcific AS.
- The simplified Bernoulli approximation showed insensitivity to AS type and severity, leading to over- or underprediction of TPG, with greater errors in calcific cases.
Conclusions:
- Rheumatic AS imposes a greater hemodynamic burden on the left ventricle than calcific AS.
- Current clinical methods for TPG estimation are inadequate for differentiating between AS types and severities.
- Accurate hemodynamic assessment requires advanced modeling techniques beyond the simplified Bernoulli equation, especially for calcific AS.
