Computational Characterization of Blood Rheology and Carotid Hemodynamic Alterations under Microgravity
Abstract (300 words maximum)
Microgravity (0G) conditions alter the flow of blood in the vasculature. In a recent study, thrombosis was found in human subjects returning from long-term spaceflight, suggesting a pathological link between 0G hemodynamics and vascular disease. Computational models designed in our lab have also shown an increase in blood flow stasis and directionality in some carotid bifurcation anatomies, suggesting the possible risk posed by spaceflight 0G in atherosclerosis. In addition, 0G has also been associated with changes in blood composition, which may alter the viscous behavior of blood, causing in turn additional mechanical stress alterations in the vasculature. Based on those observations and supported by our preliminary studies, we hypothesized that the changes in hematocrit, fibrinogen concentration, and plasma viscosity in 0G deepen the hemodynamic stress abnormalities caused by 0G in the carotid bifurcation. Therefore, the objective of this study was to compare the hemodynamic stress environments in a carotid bifurcation anatomy subjected to unit gravity (1G) and 0G conditions. Rheological models were developed to predict the effects of blood composition on blood viscosity in 1G and 0G. The dependence of blood viscosity on strain rate in each case was then modeled using a Carreau-Yasuda non-Newtonian model. The model was incorporated into our previous computational fluid dynamics (CFD) carotid bifurcation model for the characterization of flow in terms of wall shear stress (WSS) directionality and magnitude. The 0G rheological model was able to capture the change in blood viscosity reported during long-term spaceflight. The incorporation of this changes into the 0G CFD model yielded a 22% decrease in WSS as compared to the previous flow predictions at peak systole, which translates to a higher degree of flow stasis and reversal in regions prone to atherosclerosis. The results demonstrate the important effects of 0G on blood.
Academic department under which the project should be listed
SPCEET - Mechanical Engineering
Primary Investigator (PI) Name
Philippe Sucosky
Computational Characterization of Blood Rheology and Carotid Hemodynamic Alterations under Microgravity
Microgravity (0G) conditions alter the flow of blood in the vasculature. In a recent study, thrombosis was found in human subjects returning from long-term spaceflight, suggesting a pathological link between 0G hemodynamics and vascular disease. Computational models designed in our lab have also shown an increase in blood flow stasis and directionality in some carotid bifurcation anatomies, suggesting the possible risk posed by spaceflight 0G in atherosclerosis. In addition, 0G has also been associated with changes in blood composition, which may alter the viscous behavior of blood, causing in turn additional mechanical stress alterations in the vasculature. Based on those observations and supported by our preliminary studies, we hypothesized that the changes in hematocrit, fibrinogen concentration, and plasma viscosity in 0G deepen the hemodynamic stress abnormalities caused by 0G in the carotid bifurcation. Therefore, the objective of this study was to compare the hemodynamic stress environments in a carotid bifurcation anatomy subjected to unit gravity (1G) and 0G conditions. Rheological models were developed to predict the effects of blood composition on blood viscosity in 1G and 0G. The dependence of blood viscosity on strain rate in each case was then modeled using a Carreau-Yasuda non-Newtonian model. The model was incorporated into our previous computational fluid dynamics (CFD) carotid bifurcation model for the characterization of flow in terms of wall shear stress (WSS) directionality and magnitude. The 0G rheological model was able to capture the change in blood viscosity reported during long-term spaceflight. The incorporation of this changes into the 0G CFD model yielded a 22% decrease in WSS as compared to the previous flow predictions at peak systole, which translates to a higher degree of flow stasis and reversal in regions prone to atherosclerosis. The results demonstrate the important effects of 0G on blood.