Non-Newtonian Blood Rheology Impacts Left Atrial Stasis in Patient-Specific Simulations

• DOI: 10.1101/2021.06.24.449801
• Publication Date: 2021-06-25T21:40:10Z
• Authors: A. Gonzalo; M. García-Villalba; L. Rossini; E. Durán; D. Vigneault; P. Martínez-Legazpi; O. Flores; J. Bermejo; E. McVeigh; A. M. Kahn; J. C. del Alamo
• Keywords: Blood stasis; Hemorheology

Abstract The lack of mechanically effective contraction the left atrium (LA) during atrial fibrillation (AF) disturbs blood flow, increasing risk thrombosis and ischemic stroke. Thrombosis is most likely in appendage (LAA), a small narrow sac where prone to stagnate. Slow flow promotes formation erythrocyte aggregates LAA, also known as rouleaux, causing viscosity gradients that are usually disregarded patient-specific simulations. To evaluate these non-Newtonian effects, we built models derived from 4D computed tomography scans patients carried out computational fluid dynamics simulations using Carreau-Yasuda constitutive relation. We examined six patients, three whom had AF LAA or history transient attacks (TIAs). modeled effects hematocrit rouleaux kinetics by varying parameterization relation modulating changes based on residence time. Comparing Newtonian indicates slow increases viscosity, altering secondary swirling flows intensifying stasis. While some can be subtle when instantaneous metrics like shear rate kinetic energy, they manifested time, which accumulates over multiple heartbeats. Our data reveal stasis worsens increases, offering potential new mechanism for clinically reported correlation between stroke incidence. In summary, submit hematocrit-dependent rheology should considered calculating indices dynamics.