WEB Treatment of Ruptured Intracranial Aneurysms

BACKGROUND AND PURPOSE:The Woven EndoBridge (WEB) device was recently introduced for intrasaccular treatment of wide-neck aneurysms without the need for adjunctive support. We present our first experience in using the WEB for small ruptured aneurysms.MATERIALS AND METHODS:During 11 months, 32 of 71 (45%) endovascularly treated acutely ruptured aneurysms were treated with the WEB. The patients were 12 men and 20 women, with a mean age of 61 years (range, 34–84 years). The mean aneurysm size was 4.9 mm, and 14 were ≤4 mm. Of 32 aneurysms, 24 (75%) had a wide neck.RESULTS:All 32 aneurysms were adequately occluded after WEB placement. There were no procedural ruptures and no complications related to the WEB device. No adjunctive stents or balloons were needed. In 3 patients, thromboembolic complications occurred. One patient developed an infarction, and 2 patients were asymptomatic. The procedural complication rate was 3%. Seven patients admitted in poor clinical grade conditions died during hospital admission due to the sequelae of SAH. In 18 patients with angiographic follow-up at 3 months, 16 aneurysms remained adequately occluded. Two aneurysms showed slight compression of the WEB without reopening. Clinical follow-up in the 25 patients who survived the hospital admission period revealed mRS 1–2 in 24 and mRS 4 in 1. There were no rebleeds from the ruptured aneurysms during follow-up.CONCLUSIONS:WEB treatment of small ruptured aneurysms was safe and effective without the need for anticoagulation, adjunctive stents, or balloons. Our preliminary experience indicates that the WEB may be a valuable alternative to coils in the treatment of acutely ruptured aneurysms.

Endovascular treatment with coils of wide-neck intracranial aneurysms remains a technical challenge. To prevent extrusion of coils from the aneurysmal sac, a temporary protection balloon or a stent can be used. However, this makes the procedure more complicated with a higher chance of complications.^1,2 With the use of stents, periprocedural dual-antiplatelet therapy is required and has to be prolonged for 3–6 months. With this anticoagulation, stent-assisted coiling in ruptured aneurysms has a higher inherent risk for early rebleed or hemorrhage in the postoperative period.³Recently, an intrasaccular flow disruptor, Woven EndoBridge (WEB; Sequent Medical, Aliso Viejo, California), has been developed. The primary use of the WEB is the treatment of bifurcation or wide-neck aneurysms without the need of adjunctive devices. There is a growing body of literature on the use of the WEB device with excellent safety and efficacy profiles. Most of the published series comprised wide-necked, unruptured aneurysms.^4–16 When the WEB became available in our hospital, our initial results in unruptured aneurysms were encouraging, and we decided to expand the indications to both ruptured and unruptured aneurysms suitable for accommodating a WEB device, regardless of neck size. Our intention was to avoid using stents or balloons in ruptured aneurysms. In this article, we present our first results of the use of the WEB device in small ruptured aneurysms.     

WEB Treatment of Intracranial Aneurysms: Clinical and Anatomic Results in the French Observatory

BACKGROUND AND PURPOSE:Flow disruption with the WEB device is a new technique for the endovascular treatment of wide-neck bifurcation aneurysms. To obtain precise data regarding the safety and efficacy of this treatment with high-quality methodology, the prospective French Observatory study was conducted. Analysis of these data is presented, including 1-year follow-up.MATERIALS AND METHODS:Patients with bifurcation aneurysms for which WEB treatment was indicated were included in this prospective, multicenter Good Clinical Practice study. Clinical data, including adverse events and clinical status at 1 month and 1 year, were collected and independently analyzed by a medical monitor. An independent core laboratory evaluated the anatomic results at 1 year following the procedure.RESULTS:Ten French neurointerventional centers included 62 patients (39 women), 33–74 years of age (mean, 56.6 ± 9.80 years) with 63 aneurysms. Aneurysm locations were the middle cerebral artery in 32 aneurysms (50.8%), anterior communicating artery in 16 (25.4%), basilar artery in 9 (14.3%), and internal carotid artery terminus in 6 (9.5%). Morbidity and mortality at 1 month were, respectively, 3.2% (2/62 patients) and 0.0% (0/62). Morbidity and mortality (unrelated to the treatment) at 1 year were, respectively, 0.0% (0/59) and 3.4% (2/59 patients). At 1 year, complete occlusion was observed in 30/58 aneurysms (51.7%); neck remnant, in 16/58 aneurysms (27.6%); and aneurysm remnant, in 12/58 aneurysms (20.7%).CONCLUSIONS:This prospective French Observatory study showed very good safety of aneurysm treatment with the WEB, with a high rate of adequate aneurysm occlusion at 1 year (79.3%).

Endovascular treatment is now the first-line therapy for both ruptured and unruptured aneurysms, but aneurysms with a complex anatomy (especially wide-neck aneurysms) are, in some cases, untreatable or difficult to treat with standard coiling.^1,2 Thus, more complex endovascular techniques have been developed, such as balloon-assisted coiling, stent-assisted coiling, and flow diversion.^3–9Flow disruption is a new endovascular approach, which involves placement of an intrasaccular device (Woven EndoBridge [WEB] aneurysm embolization system; Sequent Medical, Aliso Viejo, California), which modifies the blood flow at the level of the neck and induces aneurysmal thrombosis. The WEB was designed to treat wide-neck and bifurcation aneurysms. The device has been progressively developed from a Dual-Layer version (WEB DL) to Single-Layer (WEB SL) and Single-Layer Spherical (WEB SLS) versions. Treatment with the WEB has been evaluated in several retrospective series showing good safety results.^10–13 In addition, midterm and long-term anatomic results have been evaluated in retrospective series showing good stability of the treatment.^14,15To have a more rigorous evaluation of the safety and efficacy, 2 prospective, Good Clinical Practice series were initiated simultaneously in Europe (WEB Clinical Assessment of IntraSaccular Aneurysm Therapy [WEBCAST]) and in France (French Observatory). The short-term (6-month) results of the WEBCAST trial and a comparison of safety between the WEB DL and WEB SL/SLS in the French Observatory were published previously.^16,17 These initial analyses confirmed the good safety and efficacy of the device in the short-term. This article reports the clinical and anatomic results of the French Observatory study with midterm (1-year) follow-up.     

Woven EndoBridge Intrasaccular Flow Disrupter for the Treatment of Ruptured and Unruptured Wide-Neck Cerebral Aneurysms: Report of 55 Cases

BACKGROUND AND PURPOSE:The safety and efficacy of the Woven EndoBridge (WEB) device for the treatment of cerebral aneurysms have been investigated in several studies. Most of these studies focused on specific aneurysms or a certain WEB device. Our objective was to report the experience of 2 German centers with the WEB device, including technical feasibility, safety, and short-term angiographic outcome.MATERIALS AND METHODS:We performed a retrospective study of all ruptured and unruptured aneurysms that were treated with a WEB device (WEB Double-Layer, Single-Layer, and Single-Layer Sphere) between April 2012 and August 2014. Primary outcome measures included the feasibility of the implantation and the angiographic outcome at 3-month follow-up. Secondary outcome measures included the clinical outcome at discharge and procedural complications.RESULTS:Fifty-five aneurysms in 52 patients, including 14 ruptured aneurysms, underwent treatment with the WEB device. The median age of patients was 55 years (range, 30–75 years); 19/55 (37%) were men. The device could be deployed in all patients and was implanted in 51/55 (93%) cases. Procedural complications occurred in 6/51 (12%), comprising 2 thromboembolic events, 2 thrombus formations, 1 high-grade posterior cerebral artery stenosis, and 1 aneurysm rupture. None of these had clinical sequelae. Angiographic follow-up at 3 months was available for 44/51 (86%) aneurysms. A favorable angiographic result at 3 months was achieved in 29/44 (66%) cases, whereas the percentage of good anatomic results increased from 40% in 2012 to 75% in 2014.CONCLUSIONS:The WEB device proved to be safe. Acceptable occlusion rates can be achieved but seem to require wide experience with the device.

Endovascular treatment has become a widely accepted therapeutic option for ruptured and unruptured cerebral aneurysms.^1–4 Wide-neck or large aneurysms are difficult to treat by coil embolization without the use of intraluminal support devices such as balloons or stents. When these devices are used for the treatment of complex cerebral aneurysms, promising results have been reported.^5,6 Nevertheless, there are several limitations in the use of intraluminal support devices, such as the risk of interventional complications or the need for dual anitplatelet therapy in the case of stent-assisted coil embolization.^7,8 The Woven EndoBridge (WEB; Sequent Medical, Aliso Viejo, California) is an intrasaccular flow-disruption device that modifies blood flow at the aneurysm neck.⁹ Today the WEB is available in 3 different shapes: the WEB Double-Layer (DL), Single-Layer (SL) and Single-Layer Sphere (SLS).¹⁰ So far, initial clinical results have mostly been published for the WEB-DL, comprising the results of a prospective, multicenter study and several case series. Additionally, there are only very limited data about the feasibility of the WEB device for the treatment of ruptured aneurysms.¹⁰ Occlusion rates of 81%–92% have been reported when the WEB-DL was implanted.^11–13 In ruptured aneurysms, occlusion rates of 67% have been reported.¹⁰ All studies reported high rates of neck remnants, which have been shown to represent an inflow into the recess of the WEB-DL in many cases.^11–13 To our knowledge, none of these studies reflect experience with ruptured and unruptured aneurysms that have been treated with all 3 types of WEB devices.     

Endovascular Treatment of Small and Very Small Intracranial Aneurysms with the Woven EndoBridge Device

BACKGROUND AND PURPOSE:The Woven EndoBridge has proved to be a safe and effective treatment, especially for wide-neck intracranial aneurysms. The recent fifth-generation Woven EndoBridge came with smaller devices. The purpose of this study was to assess the safety and efficiency of Woven EndoBridge treatment of small and very small aneurysms.MATERIALS AND METHODS:Between September 2017 and March 2020, all consecutive patients treated with a 3- or 3.5 mm-width Woven EndoBridge device were included in this retrospective intention-to-treat study. Clinical and radiologic findings were evaluated at immediate and last-available follow-up. Angiographic outcome was assessed by an external expert reader.RESULTS:One hundred twenty-eight aneurysms were treated with a fifth-generation Woven EndoBridge device including 29 with a width of ≤3.5 mm. Ten aneurysms were ruptured (34%). In 3 cases (10%), Woven EndoBridge treatment could not be performed because the aneurysm was still too small for the smallest available Woven EndoBridge device and another endovascular strategy was chosen. The median follow-up time was 11.2 months. Complete and adequate occlusion was obtained in 71% and 90% of the treated aneurysms, respectively. Retreatment was needed in 2 cases (10%). Symptomatic ischemic complications leading to transient neurologic deficits occurred in 2 cases (7%) (1 procedure-related and 1 device-related) but with full spontaneous recovery at discharge.CONCLUSIONS:The fifth-generation Woven EndoBridge device seems to be a safe and technically feasible treatment for both ruptured and unruptured small and very small intracranial aneurysms, with satisfactory occlusion rates on midterm follow-up. However, further study is needed to evaluate longer-term efficiency.

Since the publications of the results of the International Subarachnoid Aneurysm Trial (ISAT), in many centers, endovascular therapy has become the first-line treatment for intracranial aneurysms.^1,2 With an annual rupture rate of 0.36% per year, the treatment of small, unruptured, intracranial aneurysms remains disputable.³ However, independent predictors of rupture such as a history of subarachnoid hemorrhage, active smoking, location on the anterior communicating artery, and aneurysm multiplicity were identified, providing selection criteria for potential treatment. ^4-7The treatment of small and very small aneurysms is often challenging, especially for ruptured cases, in which therapeutic options are limited.^8-10 Conceived as an intrasaccular flow-disruption device, the Woven EndoBridge aneurysm embolization system (WEB; MicroVention) has proved to be a safe and effective treatment for bifurcation aneurysms.^11-14 The absence of systematic use of antiplatelet therapy in a hemorrhagic context makes the WEB therapy particularly interesting for ruptured wide-neck aneurysms.^15-17Since 2010, the device progressively evolved from an initial double-layer version to single-layer (SL-WEB) and single-layer spherical versions. Recently, the fifth-generation WEBs became available outside the United States,¹⁸ compatible with a new and smaller delivery catheter (VIA 17; MicroVention), facilitating the treatment of smaller and more distal aneurysms. The changes in the braiding design allowed the development of smaller devices (3- and 3.5-mm width).The WEB device has been evaluated in many Good clinical practice (GCP) studies, but the smaller fifth-generation devices were not included at that time. ^11,19,20 The purpose of this study was to report the follow-up results of ruptured and unruptured small and very small intracranial aneurysms treated using the new, smaller fifth-generation WEB devices.     

Morphologic and Hemodynamic Risk Factors in Ruptured Aneurysms Imaged before and after Rupture

BACKGROUND AND PURPOSE:Due to limited information about aneurysm natural history, choosing the appropriate management strategy for an unruptured aneurysm is challenging. By comparing unruptured and ruptured cases, studies have identified a variety of aneurysm morphologic and hemodynamic properties as risk factors for rupture. In this study, we investigated changes in 4 ruptured aneurysms before and after rupture and tested whether previously published risk factors identified a risk before rupture.MATERIALS AND METHODS:A retrospective review of ruptured aneurysms based on the inclusion criteria of documenting angiographic images before and after rupture was performed. Such cases are extremely rare. To minimize hemodynamic influence due to location, we selected 4 cases at the posterior communicating artery. 3D morphologic and hemodynamic analyses were applied to examine qualitative and quantitative risk factors in aneurysms before and after rupture.RESULTS:When we compared aneurysms before and after rupture, all increased in size. Volume, surface area, and morphology changed in both high and low wall shear stress areas. Aneurysm surface ratio, nonsphericity index, and pulsatility index were the only risk factors to consistently identify risk before and after aneurysm rupture for all aneurysms.CONCLUSIONS:Although changes in shape and flow properties were found before and after aneurysm rupture, in this small study, we found that some risk factors were evident as early as 2 years before rupture.

Due to limited information about aneurysm natural history, one of the biggest challenges in clinical aneurysm management is determining the risk of rupture for incidentally found aneurysms. Currently, size guidelines identified by the International Study of Unruptured Intracranial Aneurysms are the dominant criteria guiding treatment decisions.¹ Studies have suggested that the mechanisms underlying aneurysm rupture are multifactorial, and they have likewise identified different types of risk factors. For example, researchers have found that certain aneurysm shapes are risk factors that may associate aneurysm morphology with rupture.^2–4 By analyzing blood flow properties in groups of ruptured and unruptured aneurysms, reports have also shown that certain hemodynamic factors may play an important role in aneurysm rupture.^5–9 However, the morphologic and hemodynamic risk factors analyzed in these studies have generally been identified by analyzing ruptured aneurysms after rupture. Because clinical reports also suggest that aneurysms change due to rupture, how well these risk factors can actually help predict rupture has been controversial.^10–12In general, it is expected that the predictive ability of any aneurysm rupture risk factor will be higher as an aneurysm is closer to rupture. The fundamental rationale in aneurysm risk analysis based on comparing ruptured and unruptured aneurysm groups is that aneurysms that rupture have the same risk characteristics in the unruptured and ruptured states.^5–9,13 In that case, the results obtained by comparing ruptured with unruptured aneurysms can help assess the risk of rupture in as-yet-unruptured aneurysms. However, there are limited studies testing this hypothesis.In this study, we re-examined morphologic and hemodynamic risk factors that have been reported in the literature by using a unique dataset of aneurysms imaged in both their unruptured and ruptured states.^{4,6–8,14–17} Our objective was to investigate morphology and flow properties of aneurysms before and after rupture and find whether previously identified risk factors were present in aneurysms before rupture. We sought to identify risk factors that consistently existed in ruptured aneurysms in both unruptured and ruptured states to guide early determination of aneurysm rupture risk.     

Safety and Efficacy of Aneurysm Treatment with the WEB: Results of the WEBCAST 2 Study

BACKGROUND AND PURPOSE:Flow disruption with the Woven EndoBridge (WEB) device is an innovative technique for the endovascular treatment of wide-neck bifurcation aneurysms. The initial version of the device (WEB Double-Layer) was evaluated in the WEB Clinical Assessment of IntraSaccular Aneurysm Therapy (WEBCAST) study, whereas the French Observatory study evaluated both WEB Double-Layer and Single-Layer versions of the device. WEBCAST 2 was designed to evaluate the WEB Single-Layer with Enhanced Visualization.MATERIALS AND METHODS:Patients with wide-neck bifurcation aneurysms for which WEB treatment was possible were included. Clinical data including adverse events and clinical status at 1 month and 1 year were collected and analyzed. A core laboratory evaluated anatomic results at 1 year following the procedure.RESULTS:Ten European neurointerventional centers included 55 patients (38 women; 27–77 years of age; mean, 54.4 ± 10.0 years) with 55 aneurysms. Aneurysm locations were the middle cerebral artery in 25 aneurysms (45.5%), the anterior communicating artery in 16 (29.1%), the basilar artery in 9 (16.4%), and the internal carotid artery terminus in 5 (9.1%). Procedural morbidity and mortality at 1 month were, respectively, 1.8% (1/55 patients) and 0.0% (0/55 patients). Morbidity and mortality at 1 year were, respectively, 3.9% (2/51 patients) and 2.0% (1/51 patients). At 1 year, complete occlusion was observed in 27/50 aneurysms (54.0%); neck remnant, in 13/50 (26.0%); and aneurysm remnant, in 10/50 (20.0%) (adequate occlusion in 40/50, 80.0%).CONCLUSIONS:WEBCAST 2 confirms the high safety and efficacy of WEB aneurysm treatment demonstrated in the WEBCAST and French Observatory studies.

Endovascular treatment is now the first-line treatment for ruptured aneurysms.¹ For unruptured aneurysms, no randomized trial has been completed that permits the direct comparison of clipping with endovascular treatment. However, at least in Europe, the tendency is to give priority to endovascular treatment.² Some aneurysms, especially those with a wide-neck, are difficult to treat due to the challenges of stabilizing coils inside the aneurysm sac and avoiding their protrusion into the parent artery. Thus, more complex endovascular techniques have been developed, such as balloon-assisted coiling, stent-assisted coiling, and flow diversion.^3–8Flow disruption is now a well-established procedure for the treatment of wide-neck bifurcation aneurysms.^9–13 Today, it is also used in narrow-neck aneurysms and sidewall aneurysms.¹⁴ The therapy involves the placement of an intrasaccular device that alters the flow inside the aneurysm, inducing intrasaccular thrombosis. Introduced in 2010 in Europe, the Woven EndoBridge (WEB; Sequent Medical, Aliso Viejo, California) is the only intrasaccular device that has been extensively evaluated in the literature with several single- and multicenter, retrospective, and prospective series.^9–21 Good Clinical Practice studies, including the WEB Clinical Assessment of IntraSaccular Aneurysm Therapy (WEBCAST) and the French Observatory studies, have shown a high level of safety with the device.^15–18 Efficacy has to be further evaluated, but 1-year anatomic results in both the WEBCAST and French Observatory studies are encouraging. However, important changes in the device have been introduced across the time, moving from a dual-layer, larger profile version (WEB-DL) to single-layer, lower profile versions (WEB-SL and WEB Single-Layer Spherical [SLS]) and more recently Single-Layer with Enhanced Visualization (EV) obtained by introducing composite wires of nitinol and platinum in the braid itself.The WEBCAST study evaluated the WEB-DL, whereas the French Observatory evaluated the WEB-DL, WEB-SL, and the WEB-SLS.^15–18 In the continuing effort to assess the clinical and anatomic performance of these new devices, it was logical to further evaluate this technique with a series of patients treated exclusively with single-layer (SL, SLS) and Enhanced Visualization devices.     

WEB Treatment of Ruptured Intracranial Aneurysms: A Single-Center Cohort of 100 Patients

BACKGROUND AND PURPOSE:The Woven EndoBridge device was recently introduced for the intrasaccular treatment of wide-neck aneurysms without the need for adjunctive devices. We present our results of the primary treatment of ruptured aneurysms with the Woven EndoBridge regardless of location or neck size.MATERIALS AND METHODS:Between February 2015 and April 2017, 100 ruptured aneurysms were selectively treated with the Woven EndoBridge. No supporting stents or balloons were used. There were 71 women treated (mean patient age, 59 years; median age, 60 years; range, 23–82 years).RESULTS:The mean aneurysm size was 5.6 mm (range, 3–13 mm), and 42 aneurysms were ≤4 mm. Sixty-six aneurysms (66%) had a wide neck, defined as ≥4 mm or a dome-neck ratio ≤1.5. There was 1 procedural rupture without sequelae. In 9 patients (9%), thromboembolic complications occurred. One poor grade patient died; neurologic deficits remained in 3. Overall treatment-related morbidity-mortality was 4% (4 of 100; 95% CI, 1.2%–10.2%).Two of 100 aneurysms were initially incompletely occluded and were additionally treated early after initial intervention. Of 80 eligible patients, 74 (93%) had 3-month angiographic follow-up. Fifty-four aneurysms (73%) were completely occluded, 17 (23%) had a small neck remnant, and 3 (4%) were incompletely occluded. One patient was additionally treated with a second Woven EndoBridge, and in 2 patients, additional treatment is scheduled. The overall reopening/retreatment rate was 6.8% (5 of 74; 95% CI, 2.6%–15.2%). There were no rebleeds during follow-up.CONCLUSIONS:Treatment of small ruptured aneurysms with the Woven EndoBridge was safe and effective. The Woven EndoBridge proved to be a valuable alternative to coils without the need for stents or balloons.

Endovascular treatment of wide-neck intracranial aneurysms with coils mostly requires the use of a temporary protection balloon or a stent. However, this makes the procedure more complicated with a higher chance of complications.^1–4 With stents, periprocedural dual antiplatelet therapy is required and has to be prolonged for 3–6 months. With this antiaggregation regimen, stent-assisted coiling in ruptured aneurysms has a higher inherent risk for early rebleed or hemorrhage in the postoperative period. Despite antiaggregation, thromboembolic complications still occur.⁵Recently, the intrasaccular flow disruptor Woven EndoBridge (WEB; Sequent Medical, Aliso Viejo, California) device has been developed, primarily for the treatment of (bifurcation) wide-neck aneurysms without the need for adjunctive devices. The first clinical results of the WEB device show good safety and efficacy profiles. Most of the published series comprised wide-neck, unruptured aneurysms.^6–24In a previous publication, we presented our first results of the use of the WEB for all ruptured aneurysms suitable for the device, regardless of location or neck size.²⁵ Our intention was to avoid stents in the treatment of ruptured aneurysms. Our strategy was to treat ruptured wide-neck aneurysms with the WEB or, when WEB placement was not possible, with coiling or surgery. In this study, we present the results of this treatment strategy with an extended cohort of 100 patients with ruptured aneurysms treated with the WEB.     

WEB Treatment of Intracranial Aneurysms: Feasibility,Complications, and 1-Month Safety Results with the WEB DL and WEB SL/SLS in the French Observatory

BACKGROUND AND PURPOSE:Safety analyses in the French Observatory have shown that treatment of intracranial aneurysms by using flow disruption with the Woven EndoBridge Device (WEB) is safe, with low morbidity and no mortality. The objective of this study was to analyze treatment feasibility, complications, and safety results in patients treated with the Woven EndoBridge Device Dual-Layer (WEB DL) and Woven EndoBridge Device Single-Layer/Single-Layer Sphere (WEB SL/SLS) in the French Observatory.MATERIALS AND METHODS:Patients with bifurcation aneurysms were included in this prospective, multicenter good clinical practices study. A medical monitor independently analyzed procedural and clinical data. The study started with the WEB DL, and secondarily, the WEB SL/SLS was authorized in the study.RESULTS:Between November 2012 and January 2014, 10 French centers included 62 patients with 63 aneurysms. Thirty patients with 31 aneurysms were treated with the WEB DL, and 32 patients with 32 aneurysms, with the WEB SL/SLS. The percentage of anterior communicating artery aneurysms treated with WEB SL/SLS was significantly higher (37.5%) compared with WEB DL (12.9%) (P = .04). The WEB SL/SLS was more frequently used in aneurysms of <10 mm than the WEB DL (respectively, 96.9% and 67.7%; P = .002). Morbidity was similar in both groups (WEB DL, 3.3%; WEB SL/SLS, 3.1%), and mortality was 0.0% in both groups.CONCLUSIONS:This comparative study shows increased use of WEB treatment in ruptured, small, and anterior communicating artery aneurysms when using WEB SL/SLS. There was a trend toward fewer thromboembolic complications with the WEB SL/SLS. With both the WEB DL and WEB SL/SLS, the treatment was safe, with low morbidity and no mortality.

Endovascular treatment is the preferred therapeutic option for ruptured aneurysms that are anatomically suitable for endovascular coil treatment, supported by randomized studies, especially in locations less suitable for surgery.^1,2 It also has an important place in the management of unruptured aneurysms that are judged appropriate for treatment.³ Complex aneurysms (fusiform, wide-neck, large, or giant) are often untreatable or difficult to treat with standard coiling. For these complex cases, endovascular techniques such as balloon-assisted coiling, stent-assisted coiling, or flow diversion have been used with good results.^4–9Flow disruption is a new endovascular approach, which involves placement of a Woven EndoBridge Device (WEB; Sequent Medical, Aliso Viejo, California), which modifies the blood flow at the level of the neck and induces intra-aneurysmal thrombosis. The WEB was designed initially to treat wide-neck and bifurcation aneurysms. The initial clinical results have shown that treatment is feasible with a low level of complications, low morbidity, and no mortality.^10–14 The device has been progressively developed from a dual-layer version (WEB Dual-Layer [DL] aneurysm embolization system; Sequent Medical) to single-layer versions (WEB Single-Layer [SL] and WEB Single-Layer Sphere [SLS]).The French Observatory is a prospective, multicenter observational study of consecutive cases, with independent monitoring, across 10 French centers.It has 2 major objectives:

1. To carefully evaluate the safety of this treatment with an independent assessment of all adverse events and morbidity/mortality.
2. To evaluate the efficacy of this treatment at 12 and 24 months with independent core lab adjudication.

Patients treated with both WEB DL and WEB SL/SLS were included in the French Observatory. The present analysis reports the feasibility of treatment, adverse events, and morbidity/mortality at 1 month in patients treated with WEB DL and WEB SL/SLS.     

The Woven EndoBridge: a new aneurysm occlusion device

BACKGROUND AND PURPOSE:The WEB device is an intrasaccular ellipsoid braided-wire embolization device designed to provide flow disruption along the aneurysm neck. The purpose of this study was to evaluate, in an in vivo aneurysm model, the acute and chronic performance of the WEB device regarding immediacy, degree, and durability of aneurysm occlusion.MATERIALS AND METHODS:The WEB device was implanted in 24 elastase-induced aneurysms in New Zealand white rabbits and followed for 1, 3, 6, and 12 months (n = 6 at all time points). Degree of intra-aneurysmal flow disruption was graded on a 4-point scale based on DSA within 10 minutes following device implantation. Chronic aneurysm occlusion was rated by using a 3-point scale. All aneurysms were harvested for histologic analysis.RESULTS:Immediate postimplant grade 1 (complete flow cessation) was noted in 7 (29%) of 24 cases. Grade 2 (near-complete flow cessation) was noted in 13 (54%) of 24 cases. At follow-up, complete occlusion was noted in 8 (33%) of 24 cases. Near-complete aneurysm occlusion was noted in 14 (58%) of 24 cases, while incomplete occlusion was noted in 2 (8%) cases. Stable aneurysm occlusion was present in 7 (29%) of 24 cases; progressive occlusion, in 14 (58%); and recanalization, in 3 (13%) cases. Histologic findings included aneurysm cavities filled with organized thrombus with connective tissue across the aneurysm neck.CONCLUSIONS:The WEB device in experimental aneurysms demonstrated promising rates of immediate and long-term aneurysm occlusion.

Recent advances in endovascular aneurysm repair have substantially impacted our understanding of how treated aneurysms heal after embolization. Until recently, the primary focus of most aneurysm devices was on healing within the aneurysm sac. Bare platinum coils, subject to high rates of aneurysm recanalization, were modified to enhance intrasaccular organization. Unfortunately, it has yet to be proved in the clinical setting that most coil modifications perform better than bare platinum coils.^1–10Intraluminal “flow diverters,” comprising tubular braided metallic implants, have shown, in preclinical studies and in early clinical reports, the ability to achieve complete occlusion in a high proportion of aneurysms.^11–20 Excellent occlusion rates after flow-diverter therapy are seen even in large and giant aneurysms, which show recanalization rates of ≥50% after coil embolization.^21,22 The success of these new devices has refocused the attention from the aneurysm dome to the aneurysm neck as the point of relevance in aneurysm treatment. Specifically, achieving a stable construct across the aneurysm neck, irrespective of intra-aneurysmal findings, may be the best predictor of long-term occlusion.Notwithstanding the early promise of intraluminal flow diverters, important shortcomings limit widespread application of these devices. Because of the perceived risk of thromboembolism, patients treated with endoluminal flow diverters are placed on dual antiplatelet therapy. This medical therapy limits use, in most cases, to unruptured aneurysms, given the risk of hemorrhagic complications if patients require external ventricular drainage.²³ Use of these endoluminal devices is further limited in ruptured aneurysms because closure of the aneurysm is delayed by weeks or months after implantation, such that an acutely ruptured aneurysm would not be adequately protected in the short term. Furthermore, the design of the endoluminal devices renders them difficult to use in bifurcation-type aneurysms. Last, use of these devices in the vicinity of eloquent perforating arteries raises concern for stroke.In this report, we detail a new device that mimics the flow-diverting mechanism of the intraluminal flow diverters, yet is placed entirely within the aneurysm cavity. This new intrasaccular device, termed the WEB aneurysm embolization device (Sequent Medical, Aliso Viejo, California), achieves placement of a high-attenuation metallic mesh both along the aneurysm wall and across the neck, which thus functions as an intrasaccular flow diverter. The device is intended as a stand-alone therapy, without adjunctive coils placed into the aneurysm cavity or within the WEB device. Because the WEB device is intrasaccular and presents a metal mesh-filled neck not unlike a coil-packed aneurysm, we anticipate that there will be no need for antiplatelet therapy. Further, the device likely would be amenable for treatment of a broad range of aneurysms, including bifurcation-type morphologies, and does not place adjacent perforating arteries at risk. Last, the WEB device is designed to facilitate acute aneurysm occlusion, rendering it appropriate for use in ruptured aneurysms.The purpose of this study was to evaluate, in an in vivo aneurysm model, the acute and long-term performance of the WEB device regarding immediacy, degree, and durability of aneurysm occlusion.     

WEB-DL Endovascular Treatment of Wide-Neck Bifurcation Aneurysms: Long-Term Results in a European Series

BACKGROUND AND PURPOSE:Flow disruption with the WEB-DL device has been used safely for the treatment of wide-neck bifurcation aneurysms. The stability of aneurysm occlusion after this treatment was evaluated in the short and midterm, but not in the long term. This retrospective multicenter European study is the continuation of an already published series dealing with short- and midterm anatomic results and analyzes long-term data in patients treated with the WEB-DL.MATERIALS AND METHODS:Twelve European neurointerventional centers initially participated in the study. In addition to data collected for the initial publication, images obtained at long-term follow-up were collected and independently analyzed by the same experienced interventional neuroradiologist.RESULTS:Of the initial 45 patients, 26 (20 women and 6 men; 35–73 years of age; mean, 55.2 ± 10.6 years; median, 55.5 years) with 26 aneurysms treated with the WEB-DL device had long-term follow-up (median, 27.4 months). Three of 26 patients (11.5%) were retreated between short- and midterm follow-up, and none, between mid- and long-term follow-up. Long-term aneurysm occlusion in the 19 patients treated with the WEB only and not retreated during follow-up was complete occlusion in 13/19 patients (68.4%), including aneurysms with opacification of the proximal recess in 9/19 patients (47.4%), neck remnant in 3/19 patients (15.8%), and aneurysm remnant in 3/19 patients (15.8%). In all patients (100.0%), aneurysm occlusion was stable between midterm and long-term follow-up.CONCLUSIONS:The results suggest that WEB treatment of wide-neck bifurcation aneurysms offers long-term stable occlusion.

Endovascular treatment is now the first-line treatment for both ruptured and unruptured intracranial aneurysms.^1–4 However, the limitations of standard coiling have contributed to the development of new endovascular approaches, including balloon-assisted coiling, stent-assisted coiling, flow diversion, and flow disruption.⁵The WEB aneurysm embolization system (Sequent Medical, Aliso Viejo, California) is an intrasaccular device designed to disrupt the intra-aneurysmal flow at the level of the neck.^6–9 Several devices are now available in the WEB family: WEB–Dual Layer (DL) and the more recently introduced WEB–Single Layer (SL) and WEB–Single Layer Sphere (SLS).¹⁰ Initial clinical experience and recent multicenter series have shown the clinical utility of this device in wide-neck bifurcation aneurysms with high technical success and low acute morbidity and mortality.^7–11 Also, the initial WEB-DL literature suggested good efficacy with a high percentage of complete and adequate occlusion (complete occlusion or neck remnant) in the postoperative period and in the short-term follow-up. In the WEB Clinical Assessment of IntraSaccular Aneurysm Therapy (WEBCAST) trial, complete and adequate occlusion was observed in, respectively, 56.1% and 85.4% of aneurysms.¹¹ A retrospective series evaluating both short- (median, 6 months) and midterm (median, 13 months) follow-up showed adequate occlusion in, respectively, 81.1% and 89.7% of aneurysms.¹² Between short- and midterm follow-up, aneurysm occlusion was stable in 92.9% of aneurysms.Aneurysm recanalization is an important issue in endovascular therapy, and wide-neck aneurysms (typical indications for the WEB) are highly prone to recanalization.^13,14 Because the WEB is dedicated to the treatment of wide-neck bifurcation aneurysms, it is important to assess the long-term stability of aneurysm occlusion after WEB treatment. As a multicenter trial, the European study was already conducted in the first patients treated with the WEB; therefore, the decision was made to collect and analyze long-term follow-up in this series of patients when available.¹² In this initial series, it was shown that opacification of the proximal recess was always stable at midterm and that it was equivalent to complete occlusion.¹²     

Contrast-Enhanced and Time-of-Flight MRA at 3T Compared with DSA for the Follow-Up of Intracranial Aneurysms Treated with the WEB Device

BACKGROUND AND PURPOSE:Imaging follow-up at 3T of intracranial aneurysms treated with the WEB Device has not been evaluated yet. Our aim was to assess the diagnostic accuracy of 3D–time-of-flight MRA and contrast-enhanced MRA at 3T against DSA, as the criterion standard, for the follow-up of aneurysms treated with the Woven EndoBridge (WEB) system.MATERIALS AND METHODS:From June 2011 to December 2014, patients treated with the WEB in our institution, then followed for ≥6 months after treatment by MRA at 3T (3D-TOF-MRA and contrast-enhanced MRA) and DSA within 48 hours were included. Aneurysm occlusion was assessed with a simplified 2-grade scale (adequate occlusion [total occlusion + neck remnant] versus aneurysm remnant). Interobserver and intermodality agreement was evaluated by calculating the linear weighted κ. MRA test characteristics and predictive values were calculated from a 2 × 2 contingency table, by using DSA data as the standard of reference.RESULTS:Twenty-six patients with 26 WEB-treated aneurysms were included. The interobserver reproducibility was good with DSA (κ = 0.71) and contrast-enhanced-MRA (κ = 0.65) compared with moderate with 3D-TOF-MRA (κ = 0.47). Intermodality agreement with DSA was fair with both contrast-enhanced MRA (κ = 0.36) and 3D-TOF-MRA (κ = 0.36) for the evaluation of total occlusion. For aneurysm remnant detection, the prevalence was low (15%), on the basis of DSA, and both MRA techniques showed low sensitivity (25%), high specificity (100%), very good positive predictive value (100%), and very good negative predictive value (88%).CONCLUSIONS:Despite acceptable interobserver reproducibility and predictive values, the low sensitivity of contrast-enhanced MRA and 3D-TOF-MRA for aneurysm remnant detection suggests that MRA is a useful screening procedure for WEB-treated aneurysms, but similar to stents and flow diverters, DSA remains the criterion standard for follow-up.

Endovascular treatment is now the first-line treatment for the management of ruptured and unruptured intracranial aneurysms.^1–4 However, the limitations of standard coiling for complex aneurysms (large, wide-neck, or developed in a bifurcation) have contributed to the development of new endovascular approaches, including balloon-assisted coiling, stent-assisted coiling, flow diversion, and flow disruption.⁵The Woven EndoBridge (WEB) aneurysm embolization system (Sequent Medical, Aliso Viejo, California) is an intrasaccular device designed to disrupt the intra-aneurysmal flow at the level of the neck.^6,7 Initial experience with the WEB–Dual-Layer (DL) showed the clinical utility of this device in wide-neck bifurcation aneurysms with high technical success and low acute morbidity and mortality.^6–16 Several WEB devices are now available, including Single-Layer (WEB-SL), Single-Layer Sphere (WEB-SLS), and WEB-DL subtypes.^12,13 Recently, Enhanced-Visualization (EV) versions were developed to improve fluoroscopic visualization of the devices during treatment.Because of the potential risk of aneurysm recanalization after endovascular treatment, regular imaging follow-up is recommended. Digital subtraction angiography is the criterion standard for the follow-up of intracranial aneurysms after endovascular treatment but has some disadvantages, including potential neurologic complications, iodinated contrast injection, and radiation exposure. With the goal of avoiding DSA drawbacks, several MR angiography techniques have been tested to follow intracranial aneurysms. 3D-TOF-MRA and contrast-enhanced MRA (CE-MRA) at 3T are appropriate techniques for the follow-up of coiled aneurysms but have some limitations for the aneurysms treated with stents or flow diverters.^17–23 Because the WEB is a relatively new device, the value of 3D-TOF-MRA and CE-MRA for the follow-up of WEB-treated intracranial aneurysms has been evaluated in a small number of patients at 1.5T.²⁴The aim of this single-center prospective study was to assess the diagnostic accuracy of 3D-TOF-MRA and CE-MRA at 3T against DSA, as the criterion standard, for the evaluation of aneurysm occlusion after WEB treatment.     

Evaluation of the Angiographic Grading Scale in Aneurysms Treated with the WEB Device in 80 Rabbits: Correlation with Histologic Evaluation

BACKGROUND AND PURPOSE:The WEB Occlusion Score has been proposed to assess angiographic outcomes for intracranial aneurysms treated with the Woven EndoBridge (WEB) device. Using a large series of experimental aneurysms treated with the WEB, we had the following objectives: 1) to compare angiographic outcomes as measured by the WEB Occlusion Scale with histologic results, and 2) to assess interobserver and intraobserver agreement of the WEB Occlusion Scale.MATERIALS AND METHODS:Intracranial aneurysms were created in 80 rabbits and treated with WEB devices. Animals were sacrificed at last follow-up for histologic evaluation. DSA was performed just after the deployment of the device and at follow-up. Four investigators independently and retrospectively graded the DSA twice according to the WEB Occlusion Scale. One histopathologist blinded to the angiographic results graded the occlusion according to a 4-point scale patterned on the WEB Occlusion Scale. Intra- and interobserver agreement were evaluated for DSA. Follow-up angiographic grading and histologic reference were compared to determine the WEB Occlusion Scale accuracy for complete (with or without recess filling) versus incomplete occlusion and adequate (complete occlusion or neck remnant) versus inadequate occlusion.RESULTS:Inter- and intraobserver weighted κ for the angiographic WEB Occlusion Scale were, respectively, 0.76 and 0.76, indicating substantial agreement. The sensitivity and specificity of the WEB Occlusion Scale for complete occlusion at follow-up compared with the histologic reference standard were, respectively, 75% and 83.3%, with an overall accuracy of 80%. Similarly, for adequate occlusion at follow-up, sensitivity was 97.7%, specificity was 64.9%, and overall accuracy was 82.5%.CONCLUSIONS:The WEB Occlusion Scale appears to be consistent, reliable, and accurate compared with a histologic reference standard.

The Woven EndoBridge (WEB) device (Sequent Medical, Aliso Viejo, California) is a new and promising tool in the treatment of wide-neck and bifurcation intracranial aneurysms.^1–4 The endosaccular implant conforms to the aneurysm wall and spans the aneurysm neck to essentially function as a flow diverter at the aneurysm neck–parent artery interface. Initial experimental and clinical studies have demonstrated that the WEB is both safe and effective in the treatment of intracranial aneurysms.^1–9Because the mechanism of action of the device differs from that in flow diverters and endosaccular coils, developing tools to assess angiographic occlusion has become a recent priority among many neurointerventionists, and several grading scales have been proposed.^4,7–10 Perhaps the most commonly used scale is the WEB Occlusion Scale (WOS).⁷ However, none of these scales, including the WOS, has previously been validated with histologic studies, to our knowledge. In a large series of elastase-induced aneurysms in rabbits treated with the WEB device, the objectives of this study were the following: 1) to compare angiographic outcomes as measured by the WOS with histologic results, and 2) to assess interobserver and intraobserver agreement of the WOS.     

Impact of A1 Asymmetry on the Woven EndoBridge Device in Anterior Communicating Artery Aneurysms

BACKGROUND AND PURPOSE:Woven EndoBridge (WEB) devices are increasingly used to treat intracranial aneurysms. A1 asymmetry contributes to anterior communicating artery aneurysm formation and to treatment instability after coiling. We sought to evaluate whether A1 asymmetry had an impact on angiographic outcome in anterior communicating artery aneurysms treated with the WEB.MATERIALS AND METHODS:Anterior communicating artery aneurysms treated between July 2012 and July 2020 with the WEB from an institutional review board–approved database were reviewed. A1 asymmetry was categorized as the following: absence of the A1 segment on 1 side (unilateral A1) versus bilateral A1. Univariate and multivariable analyses assessed independent predictors of adequate (WEB Occlusion Scale A, B, and C) and complete occlusion (WEB Occlusion Scale A and B).RESULTS:Forty-eight individual aneurysms (47 patients) were included in the final analysis, of which 16 (33%) were acutely ruptured. The mean size was 6.5 (SD, 2.2) mm. Adequate and complete occlusion was achieved in 33 (69%) and 30 (63%) cases, respectively. Unilateral A1 was associated with significantly higher rates of adequate (92% versus 60% for bilateral A1; P = .03) and complete occlusion (92% versus 50% for bilateral A1; P < .01). Multivariable logistic regression confirmed unilateral A1 as an independent predictor of both adequate (OR = 10.6; 95% CI, 1.6–220.7; P = .04) and complete occlusion (OR = 9.5, 95% CI, 1.5–190.2; P = .04. A sensitivity analysis comparing unilateral “functional” A1 with bilateral “functional” A1 showed similar results. WEB shape modification was not influenced by the unilateral A1 configuration (P = .70).CONCLUSIONS:Anterior communicating artery aneurysms with a unilateral A1 configuration treated with WEB devices are associated with better angiographic outcome than those with bilateral A1. This finding supports the hypothesis that WEB devices are resistant to unilateral flow in the aneurysm as opposed to coils.

The efficacy and safety of the Woven EndoBridge device (WEB; MicroVention) have been widely reported in several observational studies and in prospective trials.^1,2 The device is now a reliable option for the treatment of wide-neck aneurysms. Two recent meta-analyses of WEB device use found that overall rates of complete and adequate occlusion were 53% and 80%–83.3%, respectively.^3,4The anterior communicating artery (ACoA) is a preferred site for aneurysms,⁵ and aneurysms in this location tend to have a higher risk of rupture than aneurysms in other locations.^6,7 Because of the wide variety and complexity of the anterior communicating artery anatomy, ACoA aneurysms are usually considered the most complex ones to treat. Several endovascular devices (coils, stent-assisted coiling, and flow diverters) have been specifically reported in this location to overcome this challenge.^8-10 Most pointed out the role of A1 asymmetry on the angiographic outcome.^8,10 In this situation, the WEB device appears to be an appealing solution: It can be used in wide-neck aneurysms without a stent. However, the influence of the ACoA anatomy on WEB devices is not known.Here, we aimed to report the angiographic outcomes of ACoA aneurysms treated with the WEB and to determine whether A1 asymmetry has an impact on the treatment outcome.     

Endovascular Treatment of Wide-Neck Anterior Communicating Artery Aneurysms Using WEB-DL and WEB-SL: Short-Term Results in a Multicenter Study

BACKGROUND AND PURPOSE:Endovascular treatment of wide-neck anterior communicating artery aneurysms can often be challenging. The Woven EndoBridge (WEB) device is a recently developed intrasaccular flow disrupter dedicated to endovascular treatment of intracranial aneurysms. The aim of this study was to investigate the feasibility, safety, and efficacy of the WEB Dual-Layer and WEB Single-Layer devices for the treatment of wide-neck anterior communicating artery aneurysms.MATERIALS AND METHODS:Patients with anterior communicating artery aneurysms treated with the WEB device between June 2013 and March 2014 in 5 French centers were analyzed. Procedural success, technical complications, clinical outcome at 1 month, and immediate and 3- to 6-month angiographic follow-up results were analyzed.RESULTS:Ten patients with unruptured anterior communicating artery aneurysms with a mean neck diameter of 5.4 mm were treated with the WEB. Treatment failed in 3 of the 10 aneurysms without further clinical complications. One patient developed a procedural thromboembolic event, and the other 6 had normal neurologic examination findings at 1-month follow-up. Immediate anatomic outcome evaluation showed adequate occlusion (total occlusion or neck remnant) in 6 of 7 patients. Angiographic control was obtained in all patients, including 6 adequate aneurysm occlusions (3 complete occlusions and 3 neck remnants) at short-term follow-up.CONCLUSIONS:In our small series, treatment of wide-neck anterior communicating artery aneurysms with the WEB device was feasible and safe. However, patient selection based on the aneurysm and initial angiographic findings in the parent artery is important due to the limitations of the WEB device navigation.

Coiling of intracranial aneurysms is now a well-established endovascular treatment option.^1,2 Nevertheless, in cases of wide-neck aneurysms, coiling alone has often been proved unsuitable. Balloon-assisted and stent-assisted coiling may be therapeutic options.^3–5 However, low rates of initial angiographic occlusion and high rates of recurrence are reported in such situations.^5–7 In addition, bifurcation aneurysms often require an X- or Y-configuration double-stent treatment technique that carries a higher rate of procedural complications^8–13 in addition to the complications linked to the mandatory use of dual antiplatelet therapy.^11–13The Woven EndoBridge (WEB) aneurysm embolization system (Sequent Medical, Aliso Viejo, California) is a recently developed intrasaccular flow disruptor dedicated to intracranial wide-neck aneurysm management; to date, WEB Dual-Layer (WEB-DL) feasibility, safety, and short-term angiographic findings have only been reported in a few studies, mostly in aneurysms of the middle cerebral artery, while its feasibility and results in treatment of anterior communicating artery aneurysms are not well-known.^14–18 The characteristics of the WEB device combining a large-diameter microcatheter and a relatively stiff device may hamper its placement in this location.The goal of this study was to analyze the feasibility, safety, and efficacy of WEB-DL and WEB Single-Layer (WEB-SL) flow disruptors for the treatment of wide-neck anterior communicating artery aneurysms.     

Endovascular Treatment of Intracranial Aneurysms with the WEB Device: A Systematic Review of Clinical Outcomes

BACKGROUND AND PURPOSE:Despite the improvement in technology, endovascular treatment of bifurcation intracranial wide-neck aneurysms remains challenging, mainly due to the difficulty of maintaining coils within the aneurysm sac without compromising the patency of bifurcation arteries. The Woven EndoBridge (WEB) device is a recent intrasaccular braided device specifically dedicated to treating such aneurysms with a wide neck by disrupting the flow in the aneurysmal neck and promoting progressive aneurysmal thrombosis.MATERIALS AND METHODS:Using several health data bases, we conducted a systematic review of all published studies of WEB endovascular treatment in intracranial aneurysms from 2010 onward to evaluate its efficacy and safety profile.RESULTS:The literature search identified 6 relevant studies (7 articles) including wide-neck bifurcation aneurysms in ≥80% of cases. Clinical data supporting the efficacy and safety of the WEB are limited to noncomparative cohort studies with large heterogeneity from a methodologic standpoint. The WEB deployment was feasible with a success rate of 93%–100%. Permanent morbidity (mRS of >1 at last follow-up) and mortality were measured at 2.2%–6.7% and 0%–17%, respectively. The adequate occlusion rate (total occlusion or neck remnant) varied between 65% and 85.4% at midterm follow-up (range, 3.3–27.4 months).CONCLUSIONS:Endovascular treatment of bifurcation wide-neck aneurysms with the WEB device is feasible and allows an acceptably adequate aneurysm occlusion rate; however, the rate of neck remnants is not negligible. The WEB device needs further clinical and anatomic evaluation with long-term prospective studies, especially of the risk of WEB compression. Prospective controlled studies should be encouraged.

With the emergence of detachable coils and results of the International Subarachnoid Aneurysm Trial and Barrow Ruptured Aneurysm Trial,^1,2 endovascular coiling has become the first-line option for ruptured intracranial aneurysms. It is also a widely accepted option for unruptured aneurysms that are anatomically suitable for endovascular approaches.³ However, coiling of large and wide-neck intracranial aneurysms is associated with low initial complete obliteration, a high incidence of recanalization (up to 20% at 12 months), and a 10% rate of retreatment.⁴ Promising technologies like flow-diverter stents have the potential to overcome some of the limitations of standard coiling for sidewall aneurysms,^5–7 but the management of large wide-neck bifurcation aneurysms remains challenging. Balloon and stent-assisted techniques have widened the indications for endovascular treatment of aneurysms with a wide neck and/or unfavorable anatomy that were otherwise unsuitable for coiling.^8–10 However, endovascular treatment of such complex intracranial aneurysms requires the use of complex endovascular techniques with double-stent placement in Y and X configurations. Bartolini et al¹¹ suggested that Y and X stent-assisted coiling was associated with a high rate of complications, 10% procedure-related permanent morbidity, and 1% mortality rate.In this context, a new endovascular device, the intrasaccular flow disruptor Woven EndoBridge (WEB; Sequent Medical, Aliso Viejo, California), specifically designed to treat wide-neck bifurcation intracranial aneurysms, has emerged in the past 5 years.^12–14 There is an emerging body of literature on the use of the WEB device, but to our knowledge, no study has specifically reviewed the evidence on its use. We, therefore, performed a literature review of this technique in the management of wide-neck bifurcation intracranial aneurysms. Our specific aims were to evaluate its feasibility, safety, and effectiveness to finally discuss its place in the endovascular treatment of bifurcation intracranial aneurysms.     

Flow Diversion in Ruptured Intracranial Aneurysms: A Meta-Analysis

BACKGROUND:Flow diversion is now an established technique to treat unruptured intracranial aneurysms not readily amenable to endovascular coil embolization or open microsurgical occlusion. The role of flow-diverting devices in treating ruptured aneurysms is less clear.PURPOSE:To estimate rates of angiographic occlusion and good clinical outcome in patients with ruptured intracranial aneurysms treated with flow-diverting devices.DATA SOURCES:Systematic review of Ovid MEDLINE, PubMed, Cochrane databases, and EMBASE from inception to December 2015 for articles that included ruptured aneurysms treated with flow diversion.STUDY SELECTION:One hundred seventy-two records were screened, of which 20 articles contained sufficient patient and outcome data for inclusion.DATA ANALYSIS:Clinical and radiologic characteristics, procedural details, and outcomes were extracted from these reports. Aggregated occlusion rates and clinical outcomes were analyzed by using the Fisher exact test (statistical significance, α = .05).DATA SYNTHESIS:Complete occlusion of the aneurysm was achieved in 90% of patients, and favorable clinical outcome was attained in 81%. Aneurysm size greater than 7 mm was associated with less favorable clinical outcomes (P = .027). Aneurysm size greater than 2 cm was associated with a greater risk of rerupture after treatment (P < .001).LIMITATIONS:Observational studies and case reports may be affected by reporting bias.CONCLUSIONS:Although not recommended as a first-line treatment, the use of flow diverters to treat ruptured intracranial aneurysms may allow high rates of angiographic occlusion and good clinical outcome in carefully selected patients. Aneurysm size contributes to treatment risk because the rerupture rate following treatment is higher for aneurysms larger than 2 cm.

Endovascular treatment of intracranial aneurysms with detachable coils was first described in 1991¹ and has since become an established method of aneurysm treatment. The International Study of Unruptured Intracranial Aneurysms² and Analysis of Treatment by Endovascular Approach of Nonruptured Aneurysms (ATENA)³ demonstrated the effectiveness and relative safety of endovascular coiling for unruptured aneurysms. Similarly, the International Subarachnoid Aneurysm Trial (ISAT), the Barrow Ruptured Aneurysm Trial, and other trials^4–7 have demonstrated the effectiveness and relative safety of endovascular coiling in ruptured aneurysms.In recent years, flow diverters (FDs) have emerged as a new endovascular treatment option for intracranial aneurysms. FDs are a reconstructive treatment in which altered flow within an aneurysm induces gradual remodeling and eventual thrombosis of the aneurysm. Several studies have demonstrated good safety and efficacy of FDs for the treatment of unruptured intracranial aneurysms,^8–17 though the safe use of these devices requires the use of dual antiplatelet therapy.^18–20Understandably, the need for antiplatelet medications and the delayed nature of aneurysm thrombosis have tempered enthusiasm for using FDs for ruptured aneurysms. Nevertheless, several reports have described the use of FDs to treat recently ruptured aneurysms, particularly those that are difficult to treat by other endovascular or open microsurgical techniques.In this meta-analysis, we review the outcomes associated with the use of FDs for the treatment of ruptured intracranial aneurysms. Specifically, we review aneurysm characteristics and endovascular treatment strategies in relation to the rates of angiographic occlusion and good clinical outcome, with the overall goal of guiding FD use in ruptured aneurysms when other treatment options are not viable.     

WEB Intrasaccular Flow Disruptor—Prospective,Multicenter Experience in 83 Patients with 85 Aneurysms

BACKGROUND AND PURPOSE:The safety and efficacy of WEB flow disruption have been analyzed in small, retrospective series. The object of this study was to evaluate the safety and efficacy of WEB flow disruption in a large, multicenter, prospectively collected population.MATERIALS AND METHODS:Data from all patients treated with the WEB-DL device between June 2011 and October 2013 in 11 French neurointerventional centers were prospectively collected and retrospectively analyzed. Complications occurring during and after treatment were analyzed as well as morbidity and mortality at 1 month. Aneurysm occlusion status at the last follow-up was analyzed.RESULTS:Eighty-three patients with 85 aneurysms were included in this series. Technical success was achieved in 77 patients with 79 aneurysms (92.9%). Periprocedural complications were observed in 9 patients (10.8%), leading to permanent neurologic deficits in 3 (3.9%). Morbidity and mortality at 1 month were 1.3% and 0.0%, respectively. Angiographic follow-up was performed for 65/79 aneurysms (82.3%) 3–24 months after treatment (mean, 5.3 months). Complete aneurysm occlusion was observed in 37/65 aneurysms (56.9%); neck remnant, in 23/65 (35.4%); and aneurysm remnant, in 5/65 (7.7%).CONCLUSIONS:In this large prospective series of patients, WEB flow disruption was a safe and efficient technique.

Endovascular treatment is now the first therapeutic option for ruptured aneurysms and is important in the treatment of unruptured aneurysms.^1–3 Aneurysms with a complex anatomy (fusiform, wide-neck, large, or giant) are in some cases untreatable or difficult to treat with standard coiling. For these cases, endovascular techniques such as balloon-assisted coiling, stent-assisted coiling, or flow diversion have been used with good results.^4–9The Woven Endoluminal Bridge–Dual Layer (WEB-DL; Sequent Medical, Aliso Viejo, California) is an intra-aneurysmal flow-disruption device, developed to modify the blood flow at the aneurysm neck. Preliminary clinical experience with the WEB has shown the clinical utility of this treatment in wide-neck bifurcation aneurysms. Several preliminary, small, retrospective series have shown good feasibility of the treatment, with a limited number of complications, low morbidity, and no mortality.^10–13 However, because these series were small and conducted in highly specialized centers with a careful selection of cases, there was a need for a safety analysis in a larger series of patients treated in several neurointerventional units.Regarding the efficacy of the method, these preliminary series have also shown good anatomic results but with a relatively high percentage of neck remnants (33.3%–56.7%).^10,12 Further analysis demonstrated that some of the neck remnants were, in fact, due to the opacification of the proximal recess of the WEB device.¹³ This proximal recess opacification has proved stable at midterm follow-up in a recent retrospective series that has also demonstrated good anatomic results and stability of aneurysm obliteration at midterm follow-up.¹³The first patient treated with the WEB-DL device in France was in June 2011. Since this initial case, all further consecutive cases were prospectively included in a data base. The retrospective analysis of the patients treated between June 2011 and October 2013 is presented in this article.     

WEB-DL Endovascular Treatment of Wide-Neck Bifurcation Aneurysms: Short- and Midterm Results in a European Study

BACKGROUND AND PURPOSE:Flow disruption with the WEB-DL device has been used safely for the treatment of wide-neck bifurcation aneurysms, but the stability of aneurysm occlusion after this treatment is unknown. This retrospective multicenter European study analyzed short- and midterm data in patients treated with WEB-DL.MATERIALS AND METHODS:Twelve European neurointerventional centers participated in the study. Clinical data and pre- and postoperative short- and midterm images were collected. An experienced interventional neuroradiologist independently analyzed the images. Aneurysm occlusion was classified into 4 grades: complete occlusion, opacification of the proximal recess of the device, neck remnant, and aneurysm remnant.RESULTS:Forty-five patients (34 women and 11 men) 35–74 years of age (mean, 56.3 ± 9.6 years) with 45 aneurysms treated with the WEB device were included. Aneurysm locations were the middle cerebral artery in 26 patients, the posterior circulation in 13 patients, the anterior communicating artery in 5 patients, and the internal carotid artery terminus in 1 patient. Forty-two aneurysms were unruptured. Good clinical outcome (mRS < 2) was observed in 93.3% of patients at the last follow-up. Adequate occlusion (complete occlusion, opacification of the proximal recess, or neck remnant) was observed in 30/37 patients (81.1%) in short-term follow-up (median, 6 months) and in 26/29 patients (89.7%) in midterm follow-up (median, 13 months). Worsening of the aneurysm occlusion was observed in 2/28 patients (7.1%) at midterm follow-up.CONCLUSIONS:The results suggest that the WEB endovascular treatment of wide-neck bifurcation aneurysms offers stable occlusion in a class of aneurysms that are historically unstable. Additionally, our data show that opacification of the WEB recess can be delineated from true neck or aneurysm remnants.

Endovascular treatment is now the first-line approach for both ruptured and unruptured aneurysms.^1–4 However, the limitations of standard coiling have contributed to the development of new endovascular approaches, including balloon-assisted coiling, stent-assisted coiling, flow diversion, and flow disruption.⁵The WEB (Sequent Medical, Aliso Viejo, California) is an intrasaccular device designed to disrupt the intra-aneurysmal flow at the level of the neck.^6–9 Several devices are now available in the WEB family: WEB-DL and the more recently introduced WEB-SL and WEB-SLS. Initial experience with the WEB-DL has shown the clinical utility of this device in wide-neck bifurcation aneurysms with high technical success and low acute morbidity and mortality.^7–9 Also, the initial WEB-DL literature suggests good efficacy, with a high percentage of adequate occlusion (complete occlusion or neck remnant) in the postoperative period and in short-term follow-up. In the largest series, a significant number of neck remnants were observed at follow-up (56.7%).⁹ This was due, in part, to the shape of the WEB-DL. The proximal surface of the WEB-DL is not flat but has a recess, which is concave from the direction of the parent artery. The WEB-DL and its recess conform to the aneurysm on the basis of the physician''s WEB-DL size choice. For example, the physician may choose to minimize the WEB-DL parent vessel protrusion by allowing the recess to form within the aneurysm sac; however, this contributes to the appearance of a neck remnant, though this remnant is located centrally and proximally relative to the WEB-DL. Alternatively, with a different WEB-DL size choice, the recess can be removed and the proximal portion of the WEB-DL resides in the neck/parent vessel interface as a flow divider.Aneurysm coil recanalization is an important issue in endovascular therapy, with approximately 20% of coiled aneurysms recanalized and 10% retreated.¹⁰ As previously shown, wide-neck aneurysms are highly prone to recanalization.¹¹The goal of this retrospective, multicenter, European study was to analyze the midterm clinical outcome, short- (3–8 months) and midterm (≥9 months) anatomic results after WEB-DL aneurysm treatment, and the stability of the treatment as well as the rate of retreatment. A point of particular interest was to determine whether the opacification of the proximal recess was stable with time or was a feature promoting aneurysm recanalization.     

Efficacy and Safety of the Woven EndoBridge (WEB) Device for the Treatment of Intracranial Aneurysms: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE:Intrasaccular flow diverters are increasingly being used in the treatment of wide-neck and bifurcation aneurysms. We performed a systematic review and meta-analysis of existing literature on the Woven EndoBridge device in the treatment of intracranial aneurysms.MATERIALS AND METHODS:A comprehensive literature search was performed through October 1, 2015. We extracted information on baseline aneurysm and patient characteristics. Outcomes studied included immediate and midterm (>3 month) angiographic outcomes (complete occlusion as well as adequate occlusion, defined as complete occlusion or neck remnant), aneurysm retreatment, intraoperative rupture, perioperative morbidity and mortality, thromboembolic complications, and treatment failure. Meta-analysis was performed by using the random-effects model.RESULTS:Fifteen uncontrolled series were included in this analysis, including 565 patients with 588 aneurysms, of which 127 were ruptured. Initial complete and adequate occlusion rates were 27% (95% CI, 15%–39%) and 59% (95% CI, 39%–78%), respectively. Midterm complete and adequate occlusion rates after a median of 7 months were 39% (95% CI, 26%–52%) and 85% (95% CI, 78%–91%), respectively. Perioperative morbidity and mortality rates were 4% (95% CI, 1%–8%) and 1% (95% CI, 0%–2%), respectively. Midterm adequate occlusion rates for ruptured aneurysms were 85% (95% CI, 67%–98%), compared with 84% (95% CI, 72%–94%) for unruptured aneurysms (P = .89). Patients with ruptured aneurysm had similar rates of perioperative morbidity to patients with unruptured aneurysm (2%; 95% CI, 0%–26% versus 2%; 95% CI, 0%–6%, respectively; P = .35).CONCLUSIONS:Early evidence derived from uncontrolled studies suggests that Woven EndoBridge treatment has a good safety profile and promising rates of adequate occlusion, especially given the complexity of aneurysms treated. Further prospective clinical trials are needed to confirm these results and better define the risks and benefits of use of the Woven EndoBridge device in treating wide-neck and wide-neck bifurcation aneurysms.

With the advent of stent-assisted and balloon-assisted coiling, wide-neck and wide-neck bifurcation intracranial aneurysms are increasingly treated with endovascular techniques. Both stent-assisted and balloon-assisted coiling have been shown safe and effective in treating these aneurysms by allowing for increased packing and lower rates of parent artery occlusion compared with conventional coiling alone.^1–7 However, because of less than satisfactory occlusion rates with coil embolization of wide-neck and wide-neck bifurcation aneurysms, there has been a push toward treating these lesions with intrasaccular and intraluminal flow diverters.The Woven EndoBridge (WEB; Sequent Medical, Aliso Viejo, California) is a nitinol braided-wire intravascular device designed to disrupt blood flow at the aneurysmal neck. This device is specifically designed for the treatment of wide-neck bifurcation aneurysms.^8,9 To date, several case series have demonstrated that the WEB device is both safe and effective in treatment of wide-neck and wide-neck bifurcation aneurysms.^10–13 We present the results of a systematic review and meta-analysis examining outcomes of endovascular treatment of wide-neck and wide-neck bifurcation aneurysms with the WEB device. The aim of our study was to assess both angiographic and clinical outcomes.     

Hemodynamic Differences in Intracranial Aneurysms before and after Rupture

BACKGROUND AND PURPOSE:Rupture risk of intracranial aneurysms may depend on hemodynamic characteristics. This has been assessed by comparing hemodynamic data of ruptured and unruptured aneurysms. However, aneurysm geometry may change before, during, or just after rupture; this difference causes potential changes in hemodynamics. We assessed changes in hemodynamics in a series of intracranial aneurysms, by using 3D imaging before and after rupture.MATERIALS AND METHODS:For 9 aneurysms in 9 patients, we used MRA, CTA, and 3D rotational angiography before and after rupture to generate geometric models of the aneurysm and perianeurysmal vasculature. Intra-aneurysmal hemodynamics were simulated by using computational fluid dynamics. Two neuroradiologists qualitatively assessed flow complexity, flow stability, inflow concentration, and flow impingement in consensus, by using flow-velocity streamlines and wall shear stress distributions.RESULTS:Hemodynamics changed in 6 of the 9 aneurysms. The median time between imaging before and after rupture was 678 days (range, 14–1461 days) in these 6 cases, compared with 151 days (range, 34–183 days) in the 3 cases with unaltered hemodynamics. Changes were observed for flow complexity (n = 3), flow stability (n = 3), inflow concentration (n = 2), and region of flow impingement (n = 3). These changes were in all instances associated with aneurysm displacement due to rupture-related hematomas, growth, or newly formed lobulations.CONCLUSIONS:Hemodynamic characteristics of intracranial aneurysms can be altered by geometric changes before, during, or just after rupture. Associations of hemodynamic characteristics with aneurysm rupture obtained from case-control studies comparing ruptured with unruptured aneurysms should therefore be interpreted with caution.

Intracranial aneurysms are found in 1%–5% of the adult population.^1,2 For ruptured intracranial aneurysms, case morbidity and fatality rates are high.^1,3 However, 50%–80% of all intracranial aneurysms do not rupture during an individual''s lifetime.¹ More commonly, unruptured aneurysms are incidentally found due to increasing use of imaging.^4,5 The risk of rupture should be balanced against the risk of treatment when deciding whether an aneurysm should be treated. In clinical practice, the location and size of the aneurysm are the most important parameters for determining the risk of rupture.^1,6 However, these geometric predictors are insufficient for optimal treatment selection. Therefore, the search for better predictors for rupture continues.^7–9 Previous studies have associated intra-aneurysmal flow patterns and wall shear stress (WSS) distributions with aneurysm rupture status.^7,8,10 However, these results are still controversial. For example, both high and low aneurysmal WSS were separately associated with aneurysm growth and rupture.^11,12 In these risk-assessment studies, potential changes in hemodynamics due to the rupture itself were systematically neglected. Recently, 2 studies have shown changes in aneurysm geometry after rupture.^13,14 These rupture-associated geometric changes may result in differences in hemodynamic characteristics as well.In this study, we had the opportunity to use high-quality 3D imaging data of 9 patients with intracranial aneurysms, obtained before and after rupture, to assess potential differences in hemodynamic characteristics associated with rupture.