Fluid-structure interaction simulations of patient-specific aortic dissection
Fluid-structure interaction simulations of patient-specific aortic dissection
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DOI：
10.1007/s10237-020-01294-8
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发表时间：
2020-01-28
影响因子：
3.5
通讯作者：
Fleischmann, Dominik
中科院分区：
文献类型：
--
作者：
Baeumler, Kathrin;Vedula, Vijay;Fleischmann, Dominik
主动脉夹层的可信计算流体动力学 (CFD) 模拟具有挑战性，因为定义的平行流道（真腔和假腔）被或多或少可移动的夹层膜彼此分隔开，夹层膜由弹性主动脉壁的分层部分组成。我们提出了一个用于主动脉夹层 CFD 模拟的综合数值框架，该框架捕捉了患者特定模型中的生理变形、血流、压力和时间平均壁剪切应力 (TAWSS) 之间的复杂相互作用。我们的数值模型包括（1）双向流固耦合（FSI）来描述血管壁和解剖瓣的动态变形； （2）预应力和（3）结构域的外部组织支撑，以避免主动脉壁的非生理性扩张和夹层瓣的拉伸； (4)通过肋间动脉和腰动脉栓系主动脉以限制主动脉的平移运动； (5) 独立定义的解剖瓣和外血管壁的弹性模量，以考虑它们不同的材料特性。患者特定的主动脉几何形状源自计算机断层扫描血管造影 (CTA)。三维相衬磁共振成像（4D 流 MRI）和患者血压用于了解生理上真实的、患者特定的边界条件。我们的模拟密切捕捉了解剖膜的周期性变形，流动模拟与 4D 流动 MRI 非常一致。我们证明，将皮瓣刚度从 Eflap=800 kPa 降低（a）使解剖皮瓣的位移从 1.4 毫米增加到 13.4 毫米，（b）将 TAWSS 的表面积减少 2.3 倍，（c）将真腔和假腔之间的平均压力差减少 0.63 倍，（d）将腹主动脉中的真腔流量减少高达 20%。我们的结论是，夹层皮瓣的活动性极大地影响局部血流动力学，因此需要在主动脉夹层的患者特异性模拟中予以考虑。准确测量皮瓣刚度及其局部变化的进一步研究有助于推进未来的 CFD 应用。
Credible computational fluid dynamic (CFD) simulations of aortic dissection are challenging, because the defining parallel flow channels-the true and the false lumen-are separated from each other by a more or less mobile dissection membrane, which is made up of a delaminated portion of the elastic aortic wall. We present a comprehensive numerical framework for CFD simulations of aortic dissection, which captures the complex interplay between physiologic deformation, flow, pressures, and time-averaged wall shear stress (TAWSS) in a patient-specific model. Our numerical model includes (1) two-way fluid-structure interaction (FSI) to describe the dynamic deformation of the vessel wall and dissection flap; (2) prestress and (3) external tissue support of the structural domain to avoid unphysiologic dilation of the aortic wall and stretching of the dissection flap; (4) tethering of the aorta by intercostal and lumbar arteries to restrict translatory motion of the aorta; and a (5) independently defined elastic modulus for the dissection flap and the outer vessel wall to account for their different material properties. The patient-specific aortic geometry is derived from computed tomography angiography (CTA). Three-dimensional phase contrast magnetic resonance imaging (4D flow MRI) and the patient's blood pressure are used to inform physiologically realistic, patient-specific boundary conditions. Our simulations closely capture the cyclical deformation of the dissection membrane, with flow simulations in good agreement with 4D flow MRI. We demonstrate that decreasing flap stiffness from Eflap=800 kPa (a) increases the displacement of the dissection flap from 1.4 to 13.4 mm, (b) decreases the surface area of TAWSS by a factor of 2.3, (c) decreases the mean pressure difference between true lumen and false lumen by a factor of 0.63, and (d) decreases the true lumen flow rate by up to 20% in the abdominal aorta. We conclude that the mobility of the dissection flap substantially influences local hemodynamics and therefore needs to be accounted for in patient-specific simulations of aortic dissection. Further research to accurately measure flap stiffness and its local variations could help advance future CFD applications.