1
|
Gonzalo A, García-Villalba M, Rossini L, Durán E, Vigneault D, Martínez-Legazpi P, Flores O, Bermejo J, McVeigh E, Kahn AM, Del Alamo JC. Non-Newtonian blood rheology impacts left atrial stasis in patient-specific simulations. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2022; 38:e3597. [PMID: 35344280 PMCID: PMC9189054 DOI: 10.1002/cnm.3597] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 02/11/2022] [Accepted: 03/18/2022] [Indexed: 06/03/2023]
Abstract
The lack of mechanically effective contraction of the left atrium (LA) during atrial fibrillation (AF) disturbs blood flow, increasing the risk of thrombosis and ischemic stroke. Thrombosis is most likely in the left atrial appendage (LAA), a small narrow sac where blood is prone to stagnate. Slow flow promotes the formation of erythrocyte aggregates in the LAA, also known as rouleaux, causing viscosity gradients that are usually disregarded in patient-specific simulations. To evaluate these non-Newtonian effects, we built atrial models derived from 4D computed tomography scans of patients and carried out computational fluid dynamics simulations using the Carreau-Yasuda constitutive relation. We examined six patients, three of whom had AF and LAA thrombosis or a history of transient ischemic attacks (TIAs). We modeled the effects of hematocrit and rouleaux formation kinetics by varying the parameterization of the Carreau-Yasuda relation and modulating non-Newtonian viscosity changes based on residence time. Comparing non-Newtonian and Newtonian simulations indicates that slow flow in the LAA increases blood viscosity, altering secondary swirling flows and intensifying blood stasis. While some of these effects are subtle when examined using instantaneous metrics like shear rate or kinetic energy, they are manifested in the blood residence time, which accumulates over multiple heartbeats. Our data also reveal that LAA blood stasis worsens when hematocrit increases, offering a potential new mechanism for the clinically reported correlation between hematocrit and stroke incidence. In summary, we submit that hematocrit-dependent non-Newtonian blood rheology should be considered when calculating patient-specific blood stasis indices by computational fluid dynamics.
Collapse
Affiliation(s)
- Alejandro Gonzalo
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, USA
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
| | - Manuel García-Villalba
- Departmento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés, Spain
| | - Lorenzo Rossini
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, USA
| | - Eduardo Durán
- Departmento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés, Spain
| | - Davis Vigneault
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
| | - Pablo Martínez-Legazpi
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- Hospital General Universitario Gregorio Marañón, Madrid, Spain
| | - Oscar Flores
- Departmento de Bioingeniería e Ingeniería Aeroespacial, Universidad Carlos III de Madrid, Leganés, Spain
| | - Javier Bermejo
- Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain
- Hospital General Universitario Gregorio Marañón, Madrid, Spain
- Facultad de Medicina, Universidad Complutense de Madrid, Madrid, Spain
- CIBERCV, Madrid, Spain
| | - Elliot McVeigh
- Department of Bioengineering, University of California San Diego, La Jolla, California, USA
- Department of Radiology, University of California San Diego, La Jolla, California, USA
| | - Andrew M Kahn
- Division of Cardiovascular Medicine, University of California San Diego, La Jolla, California, USA
| | - Juan C Del Alamo
- Department of Mechanical and Aerospace Engineering, University of California San Diego, La Jolla, California, USA
- Department of Mechanical Engineering, University of Washington, Seattle, Washington, USA
- Center for Cardiovascular Biology, University of Washington, Seattle, Washington, USA
- Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington, USA
| |
Collapse
|