Fluid-Structure-Fracture Simulation of Endograft Stability in a Stent-Graft Abdominal Aortic Aneurysm Model*

Implementation of a stent-graft into an aneurysm is the most effective means to prevent rupture and aneurysm-related sudden death. Computer modeling is commonly used in abdominal aortic aneurysms to quantify the hemodynamic factors for endovascular aortic repair (EVAR). One such factor is the intrasac pressure, which is important for investigating endoleak. Endoleak is the blood flow into the aneurysmal cavity after EVAR. Stents that are optimally placed and sized can limit endoleak and reduce the risk of aneurysm rupture. We perform a novel simulation that couples fluid structure and fracture to model endoleak. The deformability of the stent and aorta is modeled through finite element analysis with appropriate constitutive models while the complex blood flow is simulated with computational fluid dynamics. We vary the system pressure to mimic the conditions of aortic blood flow to predict endoleak after EVAR. In this study, when endoleaks occur, it is due to the loss of elastic energy at the interface between the endograft and the aortic wall. We therefore propose a series of equations for the elasto-adhesive stability of an ideal seal zone.