Stent-assisted reconstructive endovascular repair of intracranial aneurysms: long-term clinical and angiographic follow-up

Abstract Background and Purpose: The development of self-expanding stents dedicated to intracranial use has significantly widened the applicability of endovascular therapy to many intracranial aneurysms. The purpose of this study was to report the angiographic and clinical outcomes of wide-necked intracranial aneurysms treated with stent. Methods: Between January 2007 and October 2011 we deployed 22 stents in 20 patients with wide-necked cerebral aneurysms. Inclusion criteria restricted the group to adult patients with wide-necked intracranial aneurysms (ruptured and unruptured lesions). Immediate post-procedural angiographic studies were performed to evaluate successful occlusion of the aneurysm as well as patency of the parent vessel. We assessed long term angiography follow-up to detect in-stent stenosis, progressive thrombosis, recurrence and need for retreatment. Clinical outcome was assessed with the modifing Ranking Scale (mRS). Results: Technical success was obtained in all 22 (100%) cases. Angiography immediately after treatment procedure showed complete occlusion in 7 aneurysms (35%), neck remnant in 11 (55%), incomplete occlusion in 1 (5%) and partial occlusion in 1 (5%). During the endovascular embolization procedure no rupture of the sac or bleeding complication occurred; none of the patients needed undergoing surgical crossover. Procedure-related adverse events occurred in one (5%) patient: a brachial artery pseudoaneurysm. Three (15%) patients had neurological complications after procedure, whose 1 (5%) transitory complication spontaneusly resolved. Two patients (10%), had acute complete in-stent thrombosis which resolved after intraarterial administration of abciximab and placement of a new stent in-stent. Of the 20 patients treated with stent deployment, a follow-up imaging study was available in all 19 surviving patients (95%) at an average of 16.2 months (range, 6 to 50 months). The first follow-up DSA, compared with initial angiography, showed no changes in 14 aneurysms (73.7%), progressive thrombosis in 3 (15.7%), and major recurrence in 2 (10.5%). The overall rate of succesful procedure to 6 months is 89.5%; there was 1 case of asintomatic moderate endothelial hyperplasia. The further follow-up imaging study, showed no changes in 17 (89.5%) of the 19 surviving patients, 1 progressive thrombosis and 1 minor recurrence. One month- and long term (average of 16.2 months; range, 6 to 50 months) clinical follow-up showed no worsening in the mRS in 18 (90%) of 20 patients, 1 (5%) mRS 2 and 1 (5%) mRS 6. All the survived patients are alive and we did not observe periprocedural or long-term intracranial bleeding events or symptomatic stent related stenosis/occlusion complication. Conclusions: Our findings suggest that the endovascular treatment of intracranial aneurysms by stenting is feasible, effective and safe; follow-up results proved intact parent arteries and stable occlusion rates in the majority of treated aneurysms. Nevertheless, long-term data on safety and efficacy and larger patient groups are necessary

Quantification of hemodynamic changes induced by virtual placement of multiple stents across a wide -necked Basilar trunk aneurysm

OBJECTIVE: The porous intravascular stents that are currently available may not cause complete aneurysm thrombosis and may therefore fail to provide durable protection against aneurysm rupture when used as a sole treatment modality. The goal of this study was to quantify the effects of porous stents on aneurysm hemodynamics using computational fluid dynamics. METHODS: The geometry of a wide-necked saccular basilar trunk aneurysm was reconstructed from a patient’s computed tomographic angiography images. Three commercial stents (Neuroform2; Boston Scientific/Target, San Leandro, CA; Wingspan; Boston Scientific, Fremont, CA; and Vision; Guidant Corp., Santa Clara, CA) were modeled. Various combinations of one to three stents were virtually conformed to fit into the vessel lumen and placed across the aneurysm orifice. An unstented aneurysm served as a control. Computational fluid dynamics analysis was performed to calculate the hemodynamic parameters considered important in aneurysm pathogenesis and thrombosis for each of the models. RESULTS: The complex flow pattern observed in the unstented aneurysm was suppressed by stenting. Stent placement lowered the wall shear stress in the aneurysm, and this effect was increased by additional stent deployment. Turnover time was moderately increased after single- and double-stent placement and markedly increased after three stents were placed. The influence of stent design on hemodynamic parameters was more significant in double-stented models than in other models. CONCLUSION: Aneurysm hemodynamic parameters were significantly modified by placement of multiple stents. Because the associated modifications may be helpful as well as harmful in terms of rupture risk, use of this technique requires careful consideration

Virtual Flow-T Stenting for Two Patient-Specific Bifurcation Aneurysms

The effective treatment of wide necked cerebral aneurysms located at vessel bifurcations (WNBAs) remains a significant challenge. Such aneurysm geometries have typically been approached with Y or T stenting configurations of stents and/or flow diverters, often with the addition of endovascular coils. In this study, two WNBAs were virtually treated by a novel T-stenting technique (Flow-T) with a number of braided stents and flow-diverter devices. Multiple possible device deployment configurations with varying device compression levels were tested, using fast-deployment algorithms, before a steady state computational hemodynamic simulation was conducted to examine the efficacy and performance of each scenario. The virtual fast deployment algorithm based on a linear and torsional spring analogy is used to accurately deploy nine stents in two WNBAs geometries. The devices expand from the distal to proximal side of the devices with respect to aneurysm sac. In the WNBAs modelled, all configurations of Flow-T device placement were shown to reduce factors linked with increased aneurysm rupture risk including aneurysm inflow jets and high aneurysm velocity, along with areas of flow impingement and elevated wall shear stress (WSS). The relative position of the flow-diverting device in the secondary daughter vessel in the Flow-T approach was found to have a negligible effect on overall effectiveness of the procedure in the two geometries considered. The level of interventionalist-applied compression in the braised stent that forms the other arm of the Flow-T approach was shown to impact the aneurysm inflow reduction and aneurysm flow pattern more substantially. In the Flow-T approach the relative position of the secondary daughter vessel flow-diverter device (the SVB) was found to have a negligible effect on inflow reduction, aneurysm flow pattern, or WSS distribution in both aneurysm geometries. This suggests that the device placement in this vessel may be of secondary importance. By contrast, substantially more variation in inflow reduction and aneurysm flow pattern was seen due to variations in braided stent (LVIS EVO or Baby Leo) compression at the aneurysm neck. As such we conclude that the success of a Flow-T procedure is primarily dictated by the level of compression that the interventionalist applies to the braided stent. Similar computationally predicted outcomes for both aneurysm geometries studied suggest that adjunct coiling approach taken in the clinical intervention of the second geometry may have been unnecessary for successful aneurysm isolation. Finally, the computational modelling framework proposed offers an effective planning platform for complex endovascular techniques, such as Flow-T, where the scope of device choice and combination is large and selecting the best strategy and device combination from several candidates is vital

Comparison of two stents in modifying cerebral aneurysm hemodynamics

There is a general lack of quantitative understanding about how specific design features of endovascular stents (struts and mesh design, porosity) affect the hemodynamics in intracranial aneurysms. To shed light on this issue, we studied two commercial high-porosity stents (Tristar stent™ and Wallstent®) in aneurysm models of varying vessel curvature as well as in a patientspecific model using Computational Fluid Dynamics. We investigated how these stents modify hemodynamic parameters such as aneurysmal inflow rate, stasis, and wall shear stress, and how such changes are related to the specific designs. We found that the flow damping effect of stents and resulting aneurysmal stasis and wall shear stress are strongly influenced by stent porosity, strut design, and mesh hole shape. We also confirmed that the damping effect is significantly reduced at higher vessel curvatures, which indicates limited usefulness of high-porosity stents as a stand-alone treatment. Finally, we showed that the stasis-inducing performance of stents in 3D geometries can be predicted from the hydraulic resistance of their flat mesh screens. From this, we propose a methodology to cost-effectively compare different stent designs before running a full 3D simulation

Indications and practical application of strategies in the endovascular management of intracranial aneurysms

The occlusion of intracranial aneurysms is more successful and stable by properly planning the approach and application of endovascular techniques. The next step is a relentless analysis of the different indications of endovascular treatment, tailoring a strategy suitable for the specific case, and making more rational choices for the management of aneurysms. Indications and strategies according to the analysis of the aneurysmal complex are given, as well as pros and cons of the endovascular technique according to different anatomical locations.       &nbsp

The Hemodynamics of Aneurysms Treated with Flow-Diverting Stents Considering both Stent and Aneurysm/Artery Geometries

Flow diverting stents are deployed to reduce the blood flow into the aneurysm, which would thereby induce thrombosis in the aneurysm sac; the stents prevent its rupture. The present study aimed to examine and quantify the impacts of different flow stents on idealized configurations of the cerebral artery. In our study, we considered a spherical sidewall aneurysm located on curved and tortuous idealized artery vessels and three stents with different porosities (70, 80 and 90%) for deployment. Using computational fluid dynamics, the local hemodynamics in the presence and absence of the stents were simulated, respectively, under the assumption that the blood flow was unsteady and non-Newtonian. The hemodynamic parameters, such as the intra-aneurysmal flow, velocity field and wall shear stress and its related indices, were examined and compared among the 12 cases simulated. The results illustrated that with the stent deployment, the intra-aneurysmal flow and the wall shear stress and its related indices were considerably modified depending on both stent and aneurysm/artery geometries, and that the intra-aneurysmal relative residence time increased rapidly with decreasing stent porosity in all the vessel configurations. These results also inform the rationale for selecting stents for treating aneurysms of different configurations

Trends in Cerebrovascular Surgery and Interventions

This is an open access proceeding book of 9th European-Japanese Cerebrovascular Congress at Milan 2018. Since many experts from Europe and Japan had very important and fruitful discussion on the management of Cerebrovascular diseases, the proceeding book is very attractive for the physician and scientists of the area

Angioplasty, Various Techniques and Challenges in Treatment of Congenital and Acquired Vascular Stenoses

The field of performing transcatheter interventions to treat vascular lesions has exploded over the past 20 years. Not only has the technology changed, especially in the arena of balloon/stent devices, but the techniques of approaching complex lesions has evolved over the past decade. Lesions that no one would have imagined treating back in the 1990's are now being done routinely in the catheterization suite. This book provides an update on the current techniques and devices used to treat a wide variety of lesions. Though, at first, the outward appearance of the topics appears to be varied, they are all related by the common thread of treating vascular lesions. We hope, by publishing this book, to accomplish two things: First, to offer insight from experts in their field to treat, both medically and procedurally, complex vascular lesions that we frequently encounter. Secondly, we hope to promote increased communication between areas of medicine that frequently don't communicate, between adult interventional cardiologists, pediatric interventional cardiologists, interventional radiologists, and neurosurgeons. Much can be learned from our respective colleagues in these areas which can further our own world of interventions