Impact of personalized blood viscosity on left atrial thrombus formation: A computational fluid dynamics study

During an episode of atrial fibrillation, the effective contractile function of the left atrium (LA) is lost, increasing the risk of thrombus formation. Notably, blood, as a typical non-Newtonian fluid, exhibits pronounced shear-thinning behavior, a phenomenon that is particularly evident in the low shear rate flow environment within the left atrial appendage (LAA). However, the predictions of existing non-Newtonian blood models show considerable differences in the low shear rate range, which brings challenges to the accurate simulation of thrombus formation risk in patient-specific LAA. This study constructs a personalized blood model based on clinical data from different patients. Using the same LA geometry, the simulation results of the personalized model were compared with those of two general non-Newtonian models, the Carreau–Yasuda model and the Cross model. The differences in thrombus risk prediction were evaluated through non-Newtonian rheological properties, from the aspects of blood stasis and endothelial damage. The results indicate that general non-Newtonian blood models have significant limitations in the precise assessment of thrombotic risk in the LAA. Meanwhile, for the same LA model, as blood viscosity increases, both the risks of blood stasis and endothelial damage increase, resulting in a higher thrombotic risk. These findings demonstrate that patient-specific non-Newtonian blood properties are critically important in hemodynamic simulations and hold significant implications for advancing precision medicine.