Stents and flow diverters in the treatment of aneurysms: device deformation in vivo may alter porosity and impact efficacy

Abstract

Alterations in porosity may occur following in vivo implantation.

Anterior Choroidal Artery Patency and Clinical Follow-Up after Coverage with the Pipeline Embolization Device

“…13,14 From this perspective, the porosities of devices covering the AchoA is likely lower than that expected in a straightvessel model, due to the relative oversizing of devices for the choroidal segment to match the diameter of the ICA at the more proximal landing zone and because the AchoA typically arises from an outer curvature of the supraclinoid ICA, causing individual device pores of the PED to be further opened. 23 In our cohort, 4 AchoAs originated from the aneurysm fundus. Of these, 2 AchoAs were impaired at follow-up and only 1 aneurysm was angiographically occluded at 1-year follow-up.…”

Tapered flow diverters in the treatment of intracranial aneurysms

“…In this transitional zone, metal coverage is lower, porosity is higher and on follow-up neointima formation is poor (14,16). In other words, as there is a direct relation between lower porosity of the 'free segment of the stent' (FSS) facing the aneurysm cavity and success of aneurysm occlusion (6,7), the increased porosity at TZ will result in sustained leak into the aneurysm and increase the risk of residual aneurysms after flow diversion (2,9,13,15,16). Focal zones of low porosity and residual flow specifically occur in curved segments or wide-neck aneurysms due to the deformation of the FD (8,13).…”

“…Focal zones of low porosity and residual flow specifically occur in curved segments or wide-neck aneurysms due to the deformation of the FD (8,13). This deformation at the TZ is a potential cause of failure of flow diversion in wide-neck curved and/or endwall aneurysms (2,(6)(7)(8)13). …”

“…Although compression and "inflation" have been used to segmentally increase the mesh density of braided endovascular prostheses (4,10) most often these techniques are insufficient to overcome the low porosity in the transition zone (2,13,15). Likewise, using FDs with higher pore density or telescoping the FD devices was not sufficient to reliably occlude giant side wall or bifurcation aneurysms (5).…”

Virtual-versus-Real Implantation of Flow Diverters: Clinical Potential and Influence of Vascular Geometry

“…10 The alteration of the porosity at the neck due to the device deformation might cause an impairment of the endothelialization of the device scaffold. 11,12 The device sizing impacting the stent porosity was shown to influence the intra-aneurysmal flow modification. 13 Currently, there is no clinical tool to predict these stent properties accurately and provide clinical insight to the practitioner.…”