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Non-Newtonian Endothelial Shear Stress Simulation: Does It Matter?
Vikas Thondapu1,2,3, Daisuke Shishikura4, Jouke Dijkstra5
1Department of Medicine, Faculty of Medicine, Melbourne Medical School, Dentistry and Health Sciences, University of Melbourne, Parkville, VIC, Australia.
Frontiers in Cardiovascular Medicine
|May 2, 2022
Summary
The non-Newtonian blood model provides more accurate endothelial shear stress (ESS) calculations than the Newtonian model, revealing higher ESS values and offering insights into atherosclerosis detection through local blood viscosity (LBV). This study highlights the importance of considering non-Newtonian blood properties in hemodynamic analysis.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Computational Fluid Dynamics
Background:
- Accurate assessment of endothelial shear stress (ESS) is crucial for understanding coronary artery disease.
- Computational Fluid Dynamics (CFD) simulations are widely used for ESS calculations, often employing simplified Newtonian blood models.
- The assumption of Newtonian blood behavior may limit the accuracy of ESS estimations in complex flow scenarios.
Purpose of the Study:
- To compare patient-specific coronary endothelial shear stress (ESS) calculations between Newtonian and non-Newtonian blood rheological models.
- To evaluate if the common assumption of Newtonian blood behavior yields similar results to a more realistic non-Newtonian model.
- To explore the utility of viscosity-based hemodynamic indices, such as local blood viscosity (LBV), in detecting atherosclerosis.
Main Methods:
- Reconstruction of 16 patient-specific coronary arteries from Optical Coherence Tomography (OCT) imaging.
- Pulsatile CFD simulations were conducted using both Newtonian and the Quemada non-Newtonian blood models.
- Comparison of calculated ESS, ESS gradient, low ESS area, and local blood viscosity (LBV) between the two models.
Main Results:
- The non-Newtonian model yielded significantly higher time-averaged ESS and ESS gradient compared to the Newtonian model (p < 0.001).
- The non-Newtonian model underestimated the low ESS (<1 Pa) area, indicating a different shear stress distribution.
- Average LBV was 1.45 times higher with the non-Newtonian model, peaking at 40-fold, suggesting significant viscosity variations.
Conclusions:
- Non-Newtonian blood models provide higher quantitative ESS values and a more accurate representation of shear stress in coronary arteries.
- Incorporating non-Newtonian blood behavior in CFD simulations can improve the accuracy of ESS measurements.
- The non-Newtonian model enables calculation of LBV, offering potential for enhanced detection of underlying atherosclerosis.
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