Computational fluid dynamics within bifurcated abdominal aortic stent-grafts.

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.