Comparison of Blood Flow in Branched and Fenestrated Stent-Grafts for Endovascular Repair of Abdominal Aortic Aneurysms.

PURPOSE

To report a computational study assessing the hemodynamic outcomes of branched stent-grafts (BSGs) for different anatomic variations.

METHODS

Idealized models of BSGs and fenestrated stent-grafts (FSGs) were constructed with different visceral takeoff angles (ToA) and lateral aortic neck angles. ToA was defined as the angle between the centerlines of the main stent-graft and side branch, with 90° representing normal alignment, and 30° and 120° representing angulated side branches. Computational simulations were performed by solving the conservation equations governing the blood flow under physiologically realistic conditions.

RESULTS

The largest renal flow recirculation zones (FRZs) were observed in FSGs at a ToA of 30°, and the smallest FRZ was also found in FSGs (at a ToA of 120°). For straight-neck stent-grafts with a ToA of 90°, mean flow in each renal artery was 0.54, 0.46, and 0.62 L/min in antegrade BSGs, retrograde BSGs, and FSGs, respectively. For angulated stent-grafts, the corresponding values were 0.53, 0.48, and 0.63 L/min. All straight-neck stent-grafts experienced equal cycle-averaged displacement forces of 1.25, 1.69, and 1.95 N at ToAs of 30°, 90°, and 120°, respectively. Angulated main stent-grafts experienced an equal cycle-averaged displacement force of 3.6 N.

CONCLUSION

The blood flow rate in renal arteries depends on the configuration of the stent-graft, with an FSG giving maximum renal flow and a retrograde BSG resulting in minimum renal flow. Nevertheless, the difference was small, up to 0.09 L/min. Displacement forces exerted on stent-grafts are very sensitive to lateral neck angle but not on the configuration of the stent-graft.