Computational Fluid Dynamics within Bifurcated Abdominal Aortic Stent-Grafts

Abstract

Purpose:

To assess the hemodynamic forces on a bifurcated abdominal aortic stent-graft under realistic conditions of flow, blood pressure, and sac pressure.

Methods:

Computational fluid dynamics was used to study the temporal and spatial variations in surface pressure and shear through the cardiac cycle on models of bifurcated stent-grafts derived from computed tomography in 4 patients who had previously undergone endovascular repair of abdominal aortic aneurysm (AAA). The trunk, bifurcation, and limbs of the graft were analyzed separately and as parts of a unified whole. Analyses were repeated under varying conditions of sac pressure, reflecting different conditions of perigraft flow and sac diameter change.

Results:

Pressure-related forces were far larger than flow-related forces in all 3 segments of all 4 cases. The largest forces acted at the bifurcation of the stent-graft. High sac pressures, seen in patients with endoleak or aneurysm dilatation, were associated with reduced transmural pressure and low-pressure—derived forces.

Conclusion:

Several parameters of stent-graft design affect the magnitude and distribution of forces on a bifurcated stent-graft. The forces on a stent-graft are also affected by the pressure within the aneurysm sac, which depends on stent-graft performance.