Asymmetric Vascular Stent

Abstract

Background and Purpose-Intracranial aneurysm (IA) treatment through hemodynamic modification with novel stent designs is a burgeoning area of research. We present a feasibility study for a new low-porosity patch-containing stent designed to treat intracranial aneurysms. The device is deployed so the patch covers the aneurysm neck ensuring strong flow diversion away from the aneurysm while keeping a low probability of occlusion of perforating vessels. Methods-We created 17 side-wall aneurysms in 6 dogs, 2 per carotid artery if animal size permitted. Twelve proximal aneurysms were treated with AVSs: 5 distal aneurysms were untreated, serving as controls against self-thrombosis; 7 treated aneurysms were fully-covered; and 5 were partially-covered. After 4 weeks, a final angiogram was performed and aneurysms were explanted. Angiograms acquired pre-and posttreatment and at 4-week follow-up were analyzed quantitatively using normalized time-density curves (NTDC). Cone-beam micro-CT and histological specimen analysis were then performed. Results-Posttreatment, NTDC average peaks dropped to 45% of initial values for the partially-covered aneurysms and 78% for the fully-covered aneurysms. Cone-beam micro-CT imaging performed at 4 weeks posttreatment showed partial thrombosis in 4 of 5 partially-covered aneurysms and complete thrombosis in all fully-covered aneurysms. Histology revealed neointimal coverage of all asymmetrical patch regions and thrombus formation in both fully-and partially-covered aneurysms. Four-week follow-up was not done for 1 animal (2 controls, 2 treated) that expired because of groin hemorrhage and for another animal (1 aneurysm) with an occluded carotid. Conclusions-We

Estimation of aneurysm wall stresses created by treatment with a shape memory polymer foam device

“…A variety of modified coils have been proposed since the FDA approval (Ahuja et al 1993; Kallmes et al 1998a; Murayama et al 1999, 2002; Tamatani et al 1997). Recently, novel devices and treatments have been proposed, such as balloon-assisted coils, flow-diversion devices (Kallmes et al 2007; Lylyk et al 2009; Szikora et al 2010; Fiorella et al 2008, 2009; Leonardi et al 2008; Appelboom et al 2010), open- and closed-cell stent designs (Ionita et al 2009, 2008; Biondi et al 2007; Liang et al 2010; Lubicz et al 2009; Fiorella et al 2006), bioactive and coated coils (Gunnarsson et al 2009; Gaba et al 2006; Geyik et al 2010; Bendszus et al 2007; Veznedaroglu et al 2008; Wakhloo et al 2007; Hirsch et al 2007), and embolic materials (Cekirge et al 2006; Molyneux et al 2004; Piske et al 2009). …”

Angiographic analysis for phantom simulations of endovascular aneurysm treatments with a new fully retrievable asymmetric flow diverter

“…The AVS consisted of low-porosity metal mesh in a relatively small, specific portion of the metal stent. 6, 7, 15, and 16 . Although the initial studies on a side wall aneurysm model generated promising results, the AVS design had substantial mechanical limitations.…”

Assessment of contrast flow modification in aneurysms treated with closed-cell self-deploying asymmetric vascular stents (SAVS)

“…The transition was from a rigid balloon deployable stainless-steel AVS to a self-expanding Nitinol stent. As our group has pointed out in previous published work6, balloon-deployable stents are not suitable for placement in remote areas of brain vasculature. The stent-balloon system is too rigid and could cause severe injuries to vessel walls.…”

“…The stent-balloon system is too rigid and could cause severe injuries to vessel walls. Also, the balloon folding used during stent crimping can cause stent rotation during deployment 6. The new type of self-expanding stent that our group has developed removes many of the issues associated with balloon deployable stents.…”

“…Current work uses a special method6 to derive time density curves normalized to the bolus injection, which is also derived from the DSA runs. The new normalized time density curves (NTDC’s) are later used to derive a set of parameters used to characterize the contrast flow modification in in-vivo aneurysms using the novel SAVS’s.…”