Changes on abdominal aortic fluid dynamics after implantation of grafts based on endovascular aneurysm sealing system (EVAS)

摘要

An innovative approach to treat abdominal aortic aneurysms, based on an endovascular aneurysm sealing system, claims to reduce both endoleak and graft migration with respect to conventional devices with proximal fixation technologies. However, the aortic bifurcation anatomy is significantly modified with this novel proposal and the hemodynamic influences on blood flow have not been addressed until now. In this work we evaluated the aortic fluid dynamics changes introduced after the implantation of a sealing device with respect to a conventional endograft on four adults with abdominal aorta aneurysms. An adaptive Geometrical Deformable Model was used for aortic segmentation and Finite Volume mesh generation. Inlet boundary conditions were set to reproduce normal physiological conditions at the abdominal aorta, and maximum pressure drop and maximum peak velocity for the models were estimated at 3 sections (proximal, mid and distal) using Computational Fluid Dynamics simulations. We found a systematic pressure increase in the proximal abdominal aorta segment for patients treated with the sealing device with respect to the more conventional endograft. Pressure values at the level of the renal arteries averaged a ≈3 mmHg pressure increase for the sealing device, compared to the ≈1 mmHg for the conventional device. Velocities inside the endograft were 4-fold higher for the sealing device with respect to the conventional device, reaching 0.41 m/s vs 0.13 m/s, respectively. Distal velocity also remained higher: 0.45 m/s vs 0.24 m/s, respectively. Although these results should be analyzed carefully due to the small number of participants, the orders of magnitude and tendencies evidence the influence that the novel sealing device has on aortic blood flow.