Geometric factors affecting the displacement forces in an aortic endograft with crossed limbs: a computational study

To compare the hemodynamic behavior between an aortic endograft model in the "crossed-limbs" configuration and the customary bifurcated deployment position under the influence of several geometric factors.

A crossed-limbs graft and its analogue model with uncrossed limbs were computationally reconstructed. The displacement forces acting over the entire endograft and at the bifurcation and iliac sites separately were calculated using a fluid structure interaction simulation under a range of specific geometric characteristics, namely, the lateral and anteroposterior (AP) neck angulation, the iliac bifurcation angulation, and the endograft curvature.

The variations of lateral neck angulation caused a constantly higher total displacement force for the crossed-limbs graft, whereas the force at the bifurcation of the two configurations differed only within a narrow range of 30° to 50°. On the contrary, the displacement force at the iliac site was higher in the crossed-limbs configuration only with lateral neck angulation >50°, reaching its highest value at 70°. The variations of AP neck angulation also caused higher total displacement forces in the crossed-limbs graft. Increasing AP neck angulation values caused generally lower forces at the crossed iliac limbs and higher at its bifurcation, respectively, compared to the uncrossed limbs model. Similarly, the influence of high iliac bifurcation angulation and endograft curvature was associated with slightly elevated forces over the entire crossed-limbs graft and its bifurcation, whereas the opposite held true at the iliac site.

Apart from minor differentiations due to geometric alterations, the customary bifurcated and crossed-limbs endografts present similar hemodynamic performance. Further clinical studies should be conducted to confirm the clinical applicability of these findings.