State Key Laboratory of Clean Energy Utilization, Zhejiang University, Hangzhou, China.
Department of Vascular Surgery, Zhongshan Hospital, Fudan University, Shanghai, China.
Comput Biol Med. 2021 Nov;138:104882. doi: 10.1016/j.compbiomed.2021.104882. Epub 2021 Sep 23.
Thoracic endovascular aortic repair (TEVAR) has developed to be the most effective treatment for aortic diseases. This study aims to evaluate the biomechanical implications of the implanted endograft after TEVAR. We present a novel image-based, patient-specific, fluid-structure computational framework. The geometries of blood, endograft, and aortic wall were reconstructed based on clinical images. Patient-specific measurement data was collected to determine the parameters of the three-element Windkessel. We designed three postoperative scenarios with rigid wall assumption, blood-wall interaction, blood-endograft-wall interplay, respectively, where a two-way fluid-structure interaction (FSI) method was applied to predict the deformation of the composite stent-wall. Computational results were validated with Doppler ultrasound data. Results show that the rigid wall assumption fails to predict the waveforms of blood outflow and energy loss (EL). The complete storage and release process of blood flow energy, which consists of four phases is captured by the FSI method. The endograft implantation would weaken the buffer function of the aorta and reduce mean EL by 19.1%. The closed curve area of wall pressure and aortic volume could indicate the EL caused by the interaction between blood flow and wall deformation, which accounts for 68.8% of the total EL. Both the FSI and endograft have a slight effect on wall shear stress-related-indices. The deformability of the composite stent-wall region is remarkably limited by the endograft. Our results highlight the importance of considering the interaction between blood flow, the implanted endograft, and the aortic wall to acquire physiologically accurate hemodynamics in post-TEVAR computational studies and the deformation of the aortic wall is responsible for the major EL of the blood flow.
胸主动脉腔内修复术（TEVAR）已发展成为治疗主动脉疾病最有效的方法。本研究旨在评估 TEVAR 后植入血管内移植物的生物力学影响。我们提出了一种新颖的基于图像的、个体化的、流固计算框架。根据临床图像重建血液、移植物和主动脉壁的几何形状。收集了患者特定的测量数据来确定三元素 Windkessel 的参数。我们设计了三种术后情况，分别为刚性壁假设、血液-壁相互作用、血液-移植物-壁相互作用，其中应用了双向流固耦合（FSI）方法来预测复合支架-壁的变形。计算结果用多普勒超声数据进行了验证。结果表明，刚性壁假设无法预测血液流出和能量损失（EL）的波形。FSI 方法捕捉到了血流能量的完全存储和释放过程，包括四个阶段。移植物植入会削弱主动脉的缓冲功能，并使平均 EL 降低 19.1%。壁压和主动脉容积的闭合曲线区域可以指示血流与壁变形相互作用引起的 EL，占 EL 总量的 68.8%。FSI 和移植物都对壁切应力相关指数有轻微影响。复合支架-壁区域的变形能力明显受到移植物的限制。我们的结果强调了在考虑血流、植入的移植物和主动脉壁之间的相互作用的重要性，以在 TEVAR 后计算研究中获得生理准确的血流动力学，并且血流的主要 EL 是由主动脉壁的变形引起的。
