American Heart Association 854091

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The objective of this study was to evaluate the extent to which non-Newtonian behavior contributes to Fontan circulation performance in pediatric patient-specific models under a low cardiac output state. In this study, we used immersed boundary-Lattice Boltzmann (IB-LBM) based CFD coupled with a physiologically accurate non-Newtonian blood model to simulate the flow in patient-specific Fontan circulations. We hypothesized that non-Newtonian characteristics increase in blood viscosity at low shear rates would increase power loss and affect hepatic blood flow distribution to the lungs. The attached STL files are three-dimensional meshes of the Fontan circulation created from cardiac magnetic resonance imaging scans. These can be utilized in any computational fluid dynamic software to calculate hemodynamic parameters of interest such as velocity, pressure, and power loss. The file "CFD boundary conditions.xlsx" contains the inflow boundary conditions that we used for each model in this study. A full description of the fluid and solid modeling parameters is provided here: Wei H, Bilgi C, Cao K, Detterich JA, Pahlevan NM, Cheng AL. The impact of blood viscosity modeling on computational fluid dynamic simulations of pediatric patients with Fontan circulation. Phys Fluids (1994). 2024 Nov;36(11):111911. doi: 10.1063/5.0236095. Epub 2024 Nov 13. PMID: 39574945; PMCID: PMC11577338. Our data showed significant differences in flow structures when comparing Newtonian and non-Newtonian models. Non-Newtonian simulations consistently exhibited significantly higher viscosity compared to Newtonian models with potential implications for thrombosis in certain patients. Non-Newtonian effects also manifested in elevated power loss, indicating that using the conventional Newtonian blood assumption might lead to a significant underestimation of both power loss and viscous dissipation and, consequently, overestimation of exercise capacity. Furthermore, non-Newtonian behavior influenced hepatic blood flow distribution in a patient-specific manner. This comprehensive exploration underscores the imperative consideration of non-Newtonian effects in the optimization of the Fontan circulation.

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