  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.
