Thoracic endovascular aortic repair (TEVAR) has developed to be the most effective treatment for aortic diseases. The objective of this study is 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. Results show that flow energy loss (EL) during a cardiac cycle is underestimated by the rigid wall assumption. The complete storage and release process of blood flow energy, which consists of four phases is firstly captured. The implantation of the endograft 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. 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 both the FSI method and the biomechanical implications of endograft to acquire physiologically-accurate hemodynamics in post-TEVAR computational studies and that neglecting the effect of the endograft would overestimate the blood flow EL and aortic deformability.
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