ObjectiveThe objective of this study was to investigate the flow effects in different degrees of thoracic aortic stent graft protrusion extension by creating bird beak effect simulations using accurate 3D geometry and a realistic, nonlinear, elastic biomechanical model using computer-aided software SolidWorks.MethodsSegmentation in 3D of an aortic arch from a computed tomography (CT) scan of a real-life patient was performed using SolidWorks. A parametric analysis of three models was performed: (A) Aortic arch with no stent, (B) 3 mm bird-beak configuration, and (C) 6.5 mm bird-beak configuration. Flow velocity, pressure, vorticity, wall shear stress (WSS), and time average WSS were assessed.ResultsThe flow velocity in Model A remained relatively constant and low in the area of the ostium of the brachiocephalic artery and doubled in the left subclavian artery. On the contrary, Models B and C showed a decrease in velocity of 52.3 % in the left subclavian artery. Furthermore, Model B showed a drop in velocity of 82.7% below the bird-beak area, whereas Model C showed a decline of 80.9% in this area. The pressure inside the supra-aortic branches was higher in Model B and C compared with Model A. In Model A, vorticity only appeared at the level of the descending aorta, with low to non-vorticity in the aortic arch. In contrast, Models B and C had an average vorticity of 241.4 Hz within the bird beak area. Regarding WSS, Model A, and Model B shared similar WSS in the peak systolic phase, in the aortic arch, and the bird beak area, whereas Model C had an increased WSS by 5 Pa on average at these zones.ConclusionIn the present simulations’ lower velocities, higher pressures, vortices, and WSS were observed around the bird beak zone, the aortic arch, and the supra-aortic vessels.

中文翻译：

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模拟鸟嘴效应的主动脉弓血流动力学分析

目的本研究的目的是通过使用精确的 3D 几何形状和计算机辅助软件 SolidWorks 的真实、非线性、弹性生物力学模型创建鸟嘴效应模拟，研究不同程度的胸主动脉覆膜支架突出延伸的流动效应。方法3D 分割使用 SolidWorks 对现实患者的计算机断层扫描 (CT) 扫描进行主动脉弓扫描。对三个模型进行了参数分析：(A) 无支架的主动脉弓、(B) 3 毫米鸟嘴配置和 (C) 6.5 毫米鸟嘴配置。评估了流速、压力、涡度、壁剪切应力（WSS）和时间平均WSS。结果模型A中的流速在头臂动脉口区域保持相对恒定且较低，在左锁骨下动脉中加倍。相反，模型B和C显示左锁骨下动脉的速度降低了52.3%。此外，模型 B 在鸟嘴区域下方的速度下降了 82.7%，而模型 C 在该区域的速度下降了 80.9%。与模型A相比，模型B和C的主动脉上支内部压力较高。在模型A中，涡度仅出现在降主动脉水平，主动脉弓处涡度低至无涡度。相比之下，模型 B 和 C 在鸟嘴区域内的平均涡度为 241.4 Hz。关于 WSS，模型 A 和模型 B 在收缩期峰值、主动脉弓和鸟嘴区域具有相似的 WSS，而模型 C 在这些区域的 WSS 平均增加了 5 Pa。结论在当前的模拟中在鸟嘴区、主动脉弓和主动脉上血管周围观察到较低的速度、较高的压力、涡流和WSS。