Simulated biomechanical responses at a curved arterial segment after Wingspan Stent deployment in swine

Abstract

Objectives: Endovascular treatment with the Wingspan Stent is frequently associated with in-stent restenosis at the curved portion, leading to late-phase stroke. To explore the cause of stroke complications after treatment with the Wingspan Stent, we simulated the biomechanical responses at a curved arterial segment using the finite element method.

Methods: A Wingspan stent was deployed at a slightly curved ascending pharyngeal artery (APA) in swine. Several stress distributions modeling solid mechanics were analyzed with structural deformation. Histopathological analysis of the selected APA was assessed at 28 days after stenting.

Results: Arterial straightening was simulated in this study. Both radial stress (RS) and circumferential stress (CS) concentrations increased at both stent ends. Marked lower axial stress (AS) concentration was observed at the outer wall of an arterial curvature. The proximal stent segment, ending in the curved portion, significantly impacted the solid mechanical environment. Eccentric neointimal hyperplasia was observed at the curved segment.

Discussion: These results show that the Wingspan stent exaggerated the non-uniform stress distributions in a curved artery. The understanding of stent–arterial wall interactions is of value to identify the current limitations of intracranial stenting, and will help to improve this treatment methodology and future devices.

Keywords:

• Intracranial atherosclerotic stenosis
• Intracranial stent
• Fine element method
• Axial stress

We thank Joyce Schumann, Fernando Mayor Basto, Fernando Viñuela Jr, and Shawn McGill for their invaluable assistance.