Combined use of stents and coils to treat experimental wide-necked carotid aneurysms: preliminary results.
ABSTRACT To develop a new technique to treat wide-necked side-wall aneurysms, combining the implantation of intraarterial stents with the endosaccular placement of coils.
Bilateral side-wall aneurysms were surgically created on the carotid arteries of four dogs. In each animal, Guglielmi detachable coils were introduced into one of the aneurysms after implantation of a balloon-expandable Strecker stent within the parent artery, adjacent to the aneurysm orifice. The contralateral aneurysms were treated with coils alone.
In two dogs, one of the stented and both nonstented aneurysms remained partially open for 4 weeks after subtotal packing with coils. In another two dogs, tight aneurysm packing with coils resulted in complete occlusion of all four aneurysms. Bulging of the coil mass resulted in 30% to 75% narrowing of the nonstented parent arteries. At 4 and 5 weeks, significant stenosis resulting from reactive hyperplasia was observed in all stented carotid arteries.
Based on these preliminary results, we conclude that Guglielmi detachable coils can be introduced into an aneurysm cavity through Strecker stents. The stents allow tighter packing of wide-necked aneurysms by preventing coils from migrating or bulging into the parent arteries.
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ABSTRACT: BACKGROUND:: Though wide-necked basilar bifurcation aneurysms are treated with Y-stent-coiling, the effect of this intervention on vessel configuration and hemodynamics is unknown. OBJECTIVE:: To investigate the immediate and delayed effects of Y-stenting using self-expanding microstents on basilar bifurcation architecture and hemodynamics. METHODS:: Fifteen patients underwent basilar Y-stent-coiling and imaging with rotational angiography. Vascular angles were measured between proximal P1 segments of the posterior cerebral arteries (α), and between the basilar artery and each P1 segment (β1,2) in the anteroposterior and (γ1,2) sagittal planes. Patient-specific computational fluid dynamic (CFD) analysis was used to estimate wall shear stress (WSS) changes with treatment. RESULTS:: In the anteroposterior plane, Y-stenting significantly decreased angle α and increased β angles immediately after stent-coiling (P<.05 and P<.01), in a continued dynamic remodeling that progressed further in later months; sagittal γ angles were also decreased (P<.0001). This novel stent-induced geometric progressive remodeling resulted in effective straightening and narrowing of the basilar bifurcation angle α (150.0° vs. 113°, P<.0001) with significant correlation (r=0.39, p<.05) between pre-treatment proximal P1 angles and maximal angular change. CFD analysis showed the angular remodeling led to significant narrowing of the WSS inter-peak at the apex, redirecting high WSS away from the neck transition zone with native vessel towards the inert coil mass. CONCLUSION:: Y-configuration stent-coiling induced immediate, and more significantly, a previously undefined delayed cerebrovascular remodeling. This progressive stent-induced angular remodeling alters peri-aneurysmal hemodynamics, independent of the flow-diverting properties of stent struts, thus shifting the balance of hemodynamic forces affecting aneurysm development and evolution. ABBREVIATIONS: BA:: Basilar artery bifurcation; CFD: Computational fluid dynamics; EN: Enterprise vascular reconstruction device/self-expanding stent; F/U: Follow-up; NF: Neuroform self-expanding stent; SAH: Subarachnoid hemorrhage; SEM: Standard error from mean; TIA: Transient ischemic attack; TX: Treatment; WSS: Wall shear stress.Neurosurgery 12/2012; · 2.53 Impact Factor
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ABSTRACT: Brain arterial aneurysms are localised dilatation in the wall of cerebral arteries that are common among adult population and associated with high incidence of morbidity and mortality. Using flow diverter stent alone to treat cerebral aneurysm is recognized as a safe and effective method. However, flow diverter stents currently available have limitations due to their braided structures. In this paper a novel flow diverter stent is proposed. It is made out of nitinol tubes that provide adequate radial stiffness and tailored surface coverage to overcome problems of currently available braided stents while retaining low porosity and excellent longitudinal flexibility. Finite element analysis using Abaqus has been conducted to investigate radial stiffness, longitudinal flexibility, and maximum strain during packaging of a series of novel stent designs with varied geometric parameters. Results show that porosity below 70% can be achieved and provides radial stiffness and longitudinal flexibility comparable to those of the Neuroform stent that is commonly used for stent assisted coiling. The novel flow diverter has showed great potential for direct treatment of cerebral aneurysms.Annals of Biomedical Engineering 01/2014; · 3.23 Impact Factor
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ABSTRACT: Objective: We sought to determine the patency of normal arterial branches from the covered segments of an artery after stenting.Background: Most intracranial aneurysms occur at arterial branching points (bifurcations, side-branches, or perforators). The post-stenting patency of normal arterial branches from the covered segments of the artery is important. We have previously developed a hybrid stent with micropores to prevent early parent artery occlusion by more early endothelialization, and mid- to long-term parent artery stenosis by control of intimal hyperplasia after aneurysm occlusion.Methods: We created aneurysms in 10 rabbits by distal ligation and intraluminal incubation of elastase within an endovascularly trapped proximal segment of the common carotid artery. All animals were treated with hybrid stents having micropores. Four animals were observed for one month and three each for three and 12 months. The patency of the side-branches of the subclavian artery was evaluated angiographically and in some cases, histologically.Results: Aneurysms were completely occluded at all time points other than 12 months. The subclavian artery and brachiocephalic artery were patent, without significant stenosis. All the side-branches of the subclavian artery detected on the preoperative angiogram remained patent at the final assessment.Conclusion: The use of hybrid stents for aneurysm repair and side-branch patency seems to be effective, as per the long-term results obtained in an animal model.Journal of Biomaterials Applications 07/2013; · 2.64 Impact Factor