Computational analysis of biomechanical contributors to possible endovascular graft failure.

This paper evaluates numerically coupled blood flow and wall structure interactions in a representative stented abdominal aortic aneurysm (AAA) model, leading potentially to endovascular graft (EVG) failure. A total of 12 biomechanical contributors to possible EVG migration were considered. The results show that after EVG insertion for the given model, the peak AAA sac-pressure was reduced to 14.2 mmHg (11.8% of p(lumen)), and hence the maximum von Mises wall stress and wall deformation dropped by factors of 20 and 10, respectively. Thus, an EVG can significantly reduce sac pressure, mechanical stress, pulsatile wall motion, and the maximum diameter in AAAs and hence prevent AAA rupture effectively. In the absence of endoleaks, elevated sac-pressure can still be caused by fluid-structure interactions between the EVG, stagnant blood, and AAA wall. EVG migration forces vary from 1.4 to 7 N for different EVG geometries, material properties, and hemodynamic conditions. AAA-neck angle, iliac bifurcation angle, neck aorta-to-iliac diameter ratio, EVG size, aorto-uni-iliac EVG, and hypertension play important roles in generating forces potentially leading to EVG migration.