Tasso Paola, Raptis Anastasios, Matsagkas Mitiadis, Rizzini Maurizio Lodi, Gallo Diego, Xenos Michalis, Morbiducci Umberto
Department of Mechanical andAerospace Engineering,Politecnico di Torino,Torino 10129, Italye-mail:
Laboratory for Vascular Simulations,Institute of Vascular Diseases,Ioannina 45500, Greecee-mail:
J Biomech Eng. 2018 Nov 1;140(11). doi: 10.1115/1.4040337.
Endovascular aneurysm repair (EVAR) has disseminated rapidly as an alternative to open surgical repair for the treatment of abdominal aortic aneurysms (AAAs), because of its reduced invasiveness, low mortality, and morbidity rate. The effectiveness of the endovascular devices used in EVAR is always at question as postoperative adverse events can lead to re-intervention or to a possible fatal scenario for the circulatory system. Motivated by the assessment of the risks related to thrombus formation, here the impact of two different commercial endovascular grafts on local hemodynamics is explored through 20 image-based computational hemodynamic models of EVAR-treated patients (N = 10 per each endograft model). Hemodynamic features, susceptible to promote thrombus formation, such as flow separation and recirculation, are quantitatively assessed and compared with the local hemodynamics established in image-based infrarenal abdominal aortic models of healthy subjects (N = 10). Moreover, the durability of endovascular devices is investigated analyzing the displacement forces (DFs) acting on them. The hemodynamic analysis is complemented by a geometrical characterization of the EVAR-induced reshaping of the infrarenal abdominal aortic vascular region. The findings of this study indicate that (1) the clinically observed propensity to thrombus formation in devices used in EVAR strategies can be explained in terms of local hemodynamics by means of image-based computational hemodynamics approach; (2) reportedly prothrombotic hemodynamic structures are strongly associated with the geometry of the aortoiliac tract postoperatively; and (3) DFs are associated with cross-sectional area of the aortoiliac tract postoperatively. In perspective, our study suggests that future clinical followup studies could include a geometric analysis of the region of the implant, monitoring shape variations that can lead to hemodynamic disturbances of clinical significance.
血管内动脉瘤修复术（EVAR）作为开放手术修复治疗腹主动脉瘤（AAA）的一种替代方法，因其侵入性小、死亡率低和发病率低而迅速普及。由于术后不良事件可能导致再次干预或引发循环系统的致命情况，用于EVAR的血管内装置的有效性一直受到质疑。受血栓形成相关风险评估的推动，本文通过20个基于图像的EVAR治疗患者的计算血流动力学模型（每个血管内移植物模型10例），探讨了两种不同商用血管内移植物对局部血流动力学的影响。对易促进血栓形成的血流动力学特征，如血流分离和再循环进行了定量评估，并与健康受试者基于图像的肾下腹主动脉模型（10例）中建立的局部血流动力学进行了比较。此外，通过分析作用在血管内装置上的位移力（DFs）来研究血管内装置的耐久性。血流动力学分析辅以对肾下腹主动脉血管区域EVAR诱导重塑的几何特征描述。本研究结果表明：（1）通过基于图像的计算血流动力学方法，可以从局部血流动力学角度解释EVAR策略中使用的装置临床上观察到的血栓形成倾向；（2）据报道促血栓形成的血流动力学结构与术后主髂动脉通道的几何形状密切相关；（3）DFs与术后主髂动脉通道的横截面积相关。从长远来看，我们的研究表明，未来的临床随访研究可能包括对植入区域的几何分析，监测可能导致具有临床意义的血流动力学紊乱的形状变化。
