Biomechanical responses after Wingspan Stent deployment in swine ascending pharyngeal artery.

OBJECTIVES

Symptomatic intracranial atherosclerotic stenosis is associated with a high rate of recurrent stroke. Endovascular angioplasty and stenting using the Wingspan(TM) Stent (Stryker) has been used for treatment of this disorder. However, a recent randomized trial (SAMMPRIS Clinical Trial) reported that it was inferior to aggressive medical management. To explore the cause of stroke complications after treatment with the Wingspan Stent, we simulated the biomechanical responses in a swine ascending pharyngeal artery (APA) using the finite element method.

METHODS

A Wingspan Stent was deployed in a swine APA, and simulated stress distributions including radial, circumferential, and wall shear stress were evaluated. Histopathological analysis of the selected APA was made 28 days post-stenting.

RESULTS

We detected increased radial stress concentration at distal stent markers with a stent edge and a graded augmentation of radial stress from proximal to distal. There was an impaired wall shear stress near the stent struts and stent markers. Intense neointimal hyperplasia was observed from the middle to distal segment of the stent 28 days after the procedure.

DISCUSSION: This preliminary data suggest that the Wingspan Stent produces increased radial stress distribution with distal segment in a tapering artery. It is possible that the radial stress concentration plays a role in the development of neointimal hyperplasia.