Sucosky Philippe, Kalaiarasan Varun Vinayak, Quasebarth Graham B, Strack Patricia, Shar Jason A
Department of Mechanical Engineering, Kennesaw State University 840 Polytechnic Lane, Engineering Technology Center, MD #9075, Marietta, GA, 30060, USA.
Department of Civil and Environmental Engineering, Kennesaw State University, 655 Arnston Drive, Civil and Environmental Engineering building, MD #9055, Marietta, GA, 30060, USA.
NPJ Microgravity. 2022 Sep 9;8(1):39. doi: 10.1038/s41526-022-00223-6.
Long-duration spaceflight poses multiple hazards to human health, including physiological changes associated with microgravity. The hemodynamic adaptations occurring upon entry into weightlessness have been associated with retrograde stagnant flow conditions and thromboembolic events in the venous vasculature but the impact of microgravity on cerebral arterial hemodynamics and function remains poorly understood. The objective of this study was to quantify the effects of microgravity on hemodynamics and wall shear stress (WSS) characteristics in 16 carotid bifurcation geometries reconstructed from ultrasonography images using computational fluid dynamics modeling. Microgravity resulted in a significant 21% increase in flow stasis index, a 22-23% decrease in WSS magnitude and a 16-26% increase in relative residence time in all bifurcation branches, while preserving WSS unidirectionality. In two anatomies, however, microgravity not only promoted flow stasis but also subjected the convex region of the external carotid arterial wall to a moderate increase in WSS bidirectionality, which contrasted with the population average trend. This study suggests that long-term exposure to microgravity has the potential to subject the vasculature to atheroprone hemodynamics and this effect is modulated by subject-specific anatomical features. The exploration of the biological impact of those microgravity-induced WSS aberrations is needed to better define the risk posed by long spaceflights on cardiovascular health.
长期太空飞行对人类健康构成多种危害，包括与微重力相关的生理变化。进入失重状态时发生的血液动力学适应与静脉血管中的逆行停滞血流状况和血栓栓塞事件有关，但微重力对脑动脉血液动力学和功能的影响仍知之甚少。本研究的目的是使用计算流体动力学模型，量化微重力对从超声图像重建的16个颈动脉分叉几何结构中的血液动力学和壁面剪应力（WSS）特征的影响。微重力导致所有分叉分支中的血流停滞指数显著增加21%，WSS大小降低22%-23%，相对停留时间增加16%-26%，同时保持WSS的单向性。然而，在两种解剖结构中，微重力不仅促进了血流停滞，还使颈外动脉壁的凸面区域的WSS双向性适度增加，这与总体平均趋势形成对比。这项研究表明，长期暴露于微重力环境可能会使血管系统处于易发生动脉粥样硬化的血液动力学状态，并且这种影响受个体特异性解剖特征的调节。需要探索这些微重力诱导的WSS异常的生物学影响，以更好地确定长期太空飞行对心血管健康构成的风险。
