Wild Nora C, Bulusu Kartik V, Plesniak Michael W
Department of Mechanical and Aerospace Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 3000, Washington, DC 20052, USA.
Department of Biomedical Engineering, The George Washington University, 800 22nd Street NW, Science & Engineering Hall, Suite 3000, Washington, DC 20052, USA.
Bioengineering (Basel). 2023 Sep 3;10(9):1036. doi: 10.3390/bioengineering10091036.
Carotid artery diseases, such as atherosclerosis, are a major cause of death in the United States. Wall shear stresses are known to prompt plaque formation, but there is limited understanding of the complex flow structures underlying these stresses and how they differ in a pre-disposed high-risk patient cohort. A 'healthy' and a novel 'pre-disposed' carotid artery bifurcation model was determined based on patient-averaged clinical data, where the 'pre-disposed' model represents a pathological anatomy. Computational fluid dynamic simulations were performed using a physiological flow based on healthy human subjects. A main hairpin vortical structure in the internal carotid artery sinus was observed, which locally increased instantaneous wall shear stress. In the pre-disposed geometry, this vortical structure starts at an earlier instance in the cardiac flow cycle and persists over a much shorter period, where the second half of the cardiac cycle is dominated by perturbed secondary flow structures and vortices. This coincides with weaker favorable axial pressure gradient peaks over the sinus for the 'pre-disposed' geometry. The findings reveal a strong correlation between vortical structures and wall shear stress and imply that an intact internal carotid artery sinus hairpin vortical structure has a physiologically beneficial role by increasing local wall shear stresses. The deterioration of this beneficial vortical structure is expected to play a significant role in atherosclerotic plaque formation.
颈动脉疾病，如动脉粥样硬化，是美国主要的死亡原因之一。已知壁面剪应力会促使斑块形成，但对于这些应力背后的复杂流动结构以及它们在易患高危患者群体中的差异，人们了解有限。基于患者平均临床数据确定了一个“健康”的和一个新型“易患”颈动脉分叉模型，其中“易患”模型代表一种病理解剖结构。使用基于健康人类受试者的生理流动进行了计算流体动力学模拟。在内颈动脉窦中观察到一个主要的发夹状涡结构，它局部增加了瞬时壁面剪应力。在易患几何结构中，这种涡结构在心动周期的更早时刻开始，并且持续时间短得多，在心动周期的后半段，由扰动的二次流动结构和涡主导。这与“易患”几何结构在窦上较弱的有利轴向压力梯度峰值相吻合。研究结果揭示了涡结构与壁面剪应力之间的强相关性，并暗示完整的内颈动脉窦发夹状涡结构通过增加局部壁面剪应力具有生理有益作用。这种有益涡结构的恶化预计在动脉粥样硬化斑块形成中起重要作用。
