Zhu Yu, Mirsadraee Saeed, Rosendahl Ulrich, Pepper John, Xu Xiao Yun
Department of Chemical Engineering, Imperial College London, London, United Kingdom.
National Heart and Lung Institute, Imperial College London, London, United Kingdom.
Front Physiol. 2022 Jun 14;13:913457. doi: 10.3389/fphys.2022.913457. eCollection 2022.
This study aimed to evaluate the effect of aortic wall compliance on intraluminal hemodynamics within surgically repaired type A aortic dissection (TAAD). Fully coupled two-way fluid-structure interaction (FSI) simulations were performed on two patient-specific post-surgery TAAD models reconstructed from computed tomography angiography images. Our FSI model incorporated prestress and different material properties for the aorta and graft. Computational results, including velocity, wall shear stress (WSS) and pressure difference between the true and false lumen, were compared between the FSI and rigid wall simulations. It was found that the FSI model predicted lower blood velocities and WSS along the dissected aorta. In particular, the area exposed to low time-averaged WSS ( ) was increased from 21 cm (rigid) to 38 cm (FSI) in patient 1 and from 35 cm (rigid) to 144 cm (FSI) in patient 2. FSI models also produced more disturbed flow where much larger regions presented with higher turbulence intensity as compared to the rigid wall models. The effect of wall compliance on pressure difference between the true and false lumen was insignificant, with the maximum difference between FSI and rigid models being less than 0.25 mmHg for the two patient-specific models. Comparisons of simulation results for models with different Young's moduli revealed that a more compliant wall resulted in further reduction in velocity and WSS magnitudes because of increased displacements. This study demonstrated the importance of FSI simulation for accurate prediction of low WSS regions in surgically repaired TAAD, but a rigid wall computational fluid dynamics simulation would be sufficient for prediction of luminal pressure difference.
本研究旨在评估主动脉壁顺应性对A型主动脉夹层（TAAD）手术修复后管腔内血流动力学的影响。对从计算机断层血管造影图像重建的两个患者特异性术后TAAD模型进行了全耦合双向流固耦合（FSI）模拟。我们的FSI模型纳入了主动脉和移植物的预应力及不同材料特性。比较了FSI模拟和刚性壁模拟的计算结果，包括速度、壁面切应力（WSS）以及真腔和假腔之间的压差。结果发现，FSI模型预测沿夹层主动脉的血流速度和WSS较低。特别是，患者1中暴露于低时间平均WSS（ ）的区域从21 cm（刚性）增加到38 cm（FSI），患者2中从35 cm（刚性）增加到144 cm（FSI）。与刚性壁模型相比，FSI模型还产生了更多紊乱的流动，其中更大的区域呈现出更高的湍流强度。壁顺应性对真腔和假腔之间压差的影响不显著，对于两个患者特异性模型，FSI模型和刚性模型之间的最大差异小于0.25 mmHg。对具有不同杨氏模量的模型的模拟结果比较表明，由于位移增加，更顺应的壁导致速度和WSS大小进一步降低。本研究证明了FSI模拟对于准确预测手术修复的TAAD中低WSS区域的重要性，但刚性壁计算流体动力学模拟足以预测管腔内压差。
