Bifurcation Aneurysms Research Articles

A comprehensive simulation framework for predicting the eCLIPs implant crimping into a catheter and its deployment mechanisms

Tubular flow diverters (FDs) represent an important subset of the endovascular treatment of cerebral aneurysms (CAs), acting to reduce aneurysm inflow, eventually resulting in aneurysm thrombosis and occlusion. eCLIPs (product of Evasc Neurovascular Enterprises, Vancouver, Canada), an innovative non-tubular implant causes flow diversion by bridging the neck of bifurcation CAs. However, in a small subset of challenging bifurcation aneurysms with fusiform pathology, the currently available eCLIPs models do not provide sufficient neck bridging resulting in a gap created between the device structure and the aneurysm/artery wall. To overcome this challenge, a new design of the eCLIPs (VR-eCLIPs) was developed by varying the rib length to cover such an inflow gap. To optimize the new product development process, and avoiding expensive and time-consuming iterative manufacture of prototype devices, we have developed a new finite element model to simulate the crimping and expansion processes of the VR-eCLIPs implant, and assess the possibility of plastic deformation. Results indicated that neither eCLIPs nor VR-eCLIPs experience plastic deformation during the crimping process. Upon full expansion, the ribs of VR-eCLIPs interact with the aneurysm and artery wall to cover the inflow gap that exists in certain challenging anatomies. This process serves as a basis to expedite design development prior to prototype manufacturing.

Numerical investigation of unruptured middle cerebral artery bifurcation aneurysms: influence of aspect ratio

An aneurysm is a disease condition, which is due to the pathological weakening of an arterial wall. These aneurysms are often found in various branch points and bifurcations of an artery in the cerebral circulation. Most aneurysms come to medical attention, either due to brain hemorrhages caused by rupture or found unruptured. To consider surgically invasive treatment modalities, clinicians need scientific methods such as, hemodynamic analysis to assess rupture risk. The arterial wall loses its structural integrity when wall shear stress (WSS) and other hemodynamic parameters exceed a certain threshold. In the present study, numerical simulations are carried out for unruptured middle cerebral artery (MCA) aneurysms. Three distinct representative sizes are chosen from a larger patient pool of 26 MCA aneurysms. Logically, these aneurysms represent three growth stages of any patient with similar anatomical structure. Simulations are performed to compare the three growth phases (with different aspect ratios) of an aneurysm and correlate their hemodynamic parameters. Simulations with patient specific boundary conditions reveal that, aneurysms with a higher aspect ratio (AR) correspond to an attendant decrease in both time-averaged wall shear stress (TAWSS) and spatial wall shear stress gradients (WSSG). Smaller MCAs were observed to have higher positive wall shear stress divergence (WSSD), exemplifying the tensile nature of arterial wall stretching. Present study identifies positive wall shear stress divergence (PWSSD) to be a potential biomarker for evaluating the growth of an aneurysm.

Abstract 111: Woven Endo Bridge‐Coil Embolization of a Middle Cerebral Artery Bifurcation Aneurysm with Secondary Lobule

Introduction 18‐36% of all intracranial aneurysms are middle cerebral artery(MCA) bifurcation aneurysms. While some are much higher risk than others, they have an overall low estimated annual rupture rate of 0.36%.(1) MCA bifurcation aneurysms have been historically challenging to treat endovascularly given they often have complex morphology and wide necks. The Woven EndoBridge (WEB) is an ellipsoid embolization device designed to provide intrasaccular flow disruption along the aneurysm neck, which has been proven to be an effective method in treating a wide spectrum of wide‐necked bifurcation aneurysms. Thromboembolism and recanalization are the main concerns in treatment with the WEB device, like any aneurysm treatment approach .(2),(3) Occasionally, irregularities and secondary lobules at the base of the primary aneurysm can have persistent filling despite treatment. Methods We present a case of a right MCA bifurcation aneurysm treated by a WEB device and coil embolization. Results 48‐year‐old female with a medical history significant only for active smoking who presented with sudden onset of the worst headache of her life followed by brief loss of consciousness. No neurological evaluation was sought initially, until 2 weeks later as she continued to experience a moderate‐intensity headache associated with nausea and vomiting with frequent falls. On exam, she was alert and oriented, moving all extremities with full strength. CT head revealed an evolving acute to subacute right MCA infarction with adjacent small volume subarachnoid hemorrhage. CTA head revealed a right MCA bifurcation aneurysm measuring 6 x 6 x 7 mm with irregularity of the wall. Multifocal severe stenosis was noted in the right distal right M1 and right M2 divisions. She underwent a diagnostic subtraction angiography which confirmed an irregular right MCA bifurcation aneurysm measuring 4.3 x 4.5 x 5.7 mm (Figure 1 ‐A,B). While it was believed that the subarachnoid hemorrhage was more likely related to the recent infarct, a decision was made to treat the aneurysm given its relatively large size and irregular shape. Embolization was performed with a WEB SL 6 x 4 mm device (Figure 1: C,D ‐blue arrow). Post‐deployment angiograph showed occlusion of the aneurysm dome but persistent filling of the secondary lobule near the base of the aneurysm. Given this residual lobule filling, a decision was made to continue additional embolization with a hyper soft 3D 2 mm X 2 cm coil(Figure 1: C,D ‐ yellow arrow). Final angiography revealed complete occlusion of the aneurysm. Vasospasm of the distal M2 divisions and multiple M3 branches in the right MCA vascular territory was also noted. Therefore, she was treated with 20 mg of intra‐arterial Verapamil with improvement. She was started on Aspirin 325 mg daily. Daily transcranial dopplers were negative for vasospasm. She remained neurologically stable and was discharged home 5 days after admission ambulating independently. Conclusion With modern advances in endovascular devices, many MCA bifurcation aneurysms can be treated minimally invasively. However, there are some limitations to the WEB since every aneurysm is different and there are a finite number of sizes and shapes available for WEB. This case illustrates that adjunctive coil embolization can successfully occlude a residual secondary base lobule after WEB embolization.

CLinical EValuation of WEB 17 device in intracranial aneuRysms (CLEVER): procedural, 30-day and 1-year safety results for ruptured and unruptured aneurysms

BackgroundIntrasaccular flow disruption is an endovascular approach for the treatment of wide-neck aneurysms and, more specifically, wide-neck bifurcation aneurysms, which are challenging to treat with previously developed technologies. The Woven...

In vitro and in silico assessment of flow modulation after deploying the Contour Neurovascular System in intracranial aneurysm models

BackgroundThe novel Contour Neurovascular System (Contour) has been reported to be efficient and safe for the treatment of intracranial, wide-necked bifurcation aneurysms. Flow in the aneurysm and posterior cerebral arteries...

Greater hemodynamic stresses initiate aneurysms on major cerebral arterial bifurcations.

To retrospectively investigate the hemodynamic stresses in initiating aneurysm formation on major cerebral arterial bifurcations with computational fluid dynamics (CFD) analysis. The cerebral 3D angiographic data of major cerebral arterial bifurcations of the internal carotid, middle cerebral, anterior cerebral, and basilar arteries in 80 patients harboring bifurcation aneurysms and 80 control subjects with no aneurysms were retrospectively collected for the CFD analysis of hemodynamic stresses associated with aneurysm formation. Bifurcation angles at major bifurcations in all patients were significantly positively (P < 0.001) correlated with the age. At the center of direct flow impingement (CDFI) on the bifurcation wall, total pressure was the highest but dropped rapidly toward the branches. Wall shear stress, dynamic pressure, strain rate, and vorticity were lowest at the CDFI but they increased quickly toward the branches. The bifurcation angle was significantly (P < 0.001) enlarged in patients with bifurcation aneurysms than those without them, for all major arterial bifurcations. Most aneurysms leaned toward the smaller arterial branch or the arterial branch that formed a smaller angle with the parent artery, where the hemodynamic stresses increased significantly (P < 0.05), compared with those on the contralateral arterial branch forming a larger angle with the parent artery. Following the aneurysm development, all the hemodynamic stresses on the aneurysm dome decreased significantly (P < 0.001) compared with those at the initiation site on the bifurcation wall after virtual aneurysm removal. With the decrease of bifurcation angles, all the hemodynamic stresses decreased. The formation of intracranial aneurysms on major intracranial arterial bifurcations is significantly associated with locally abnormally augmented hemodynamic stresses, which must be reduced.

Aneurysmal recurrence and retreatment modalities after Woven EndoBridge (WEB) device implantation: A systematic review and meta-analysis.

The Woven EndoBridge (WEB) device is used to treat wide-neck bifurcation aneurysms (WNBAs). We conducted a systematic review and meta-analysis to determine the retreatment rate strategies following aneurysmal recurrence of WEB device treated WNBAs. This study is reported following the PRISMA 2020 guidelines. We conducted a systematic review of the literature using PubMed, Scopus, Embase, and Web of Science. Data were pooled using a random-effects model. We calculated pooled prevalence and corresponding 95% confidence intervals (CI). We included 11 studies. The overall retreatment rate was 171/1875 aneurysms (10.3%; 95% CI = 8.3-12.9). Stent-assisted coiling was used to treat 59 aneurysms (36.7%; 95% CI = 26.4-48.5), and flow diverters were used to treat 44 aneurysms (18.7%; 95% CI = 9.9-32.5). Following retreatment, the complete occlusion rate was 57/91 aneurysms (62.8%; 95% CI = 48.2-75.3) and the adequate occlusion rate was 24/91 aneurysms (26.4%; 18.4%-36.4%). The most common aneurysmal recurrence site was the anterior communicating artery (44/136 aneurysms, 32.4%; 95% CI = 25.0-40.7). Roughly 10% of WNBAs initially treated with the WEB device will undergo retreatment. Retreatment is an effective strategy for WEB-treated aneurysms, with high rates of adequate and complete occlusion. Future studies should work to identify risk factors for aneurysmal recurrence.

Microsurgical Creation of Giant Bifurcation Aneurysms in Rabbits for the Evaluation of Endovascular Devices.

Giant aneurysms are dangerous lesions requiring endovascular treatment, with high rates of aneurysm recanalization and re-rupture. Reliable in vivo models are rare but are required for testing new endovascular devices.We demonstrate the technical aspects of the creation of giant bifurcation aneurysms in New Zealand white rabbits (2.5-5.5 kg). A 25-30 mm long venous pouch is taken from the external jugular vein, and a bifurcation between both carotid arteries is created microsurgically. The pouch is sutured in the bifurcation to mimic a giant aneurysm. This protocol summarizes our previously published standard technique for venous pouch true arterial bifurcation aneurysms and highlights its essential modification steps for giant aneurysms. Using this modified technique, we were able to create an animal model for giant aneurysms with high comparability to humans regarding the hemodynamics and coagulation systems. Furthermore, low morbidity and high aneurysm patency rates were achieved. The proposed giant aneurysm model offers an excellent possibility for testing new endovascular devices.

Influence of morphological characteristics on the deposition of low-density lipoprotein in intracranial bifurcation aneurysms

The increasingly demonstrated association of wall enhancement (WE) measured by vascular wall imaging with the instability/rupture of intracranial aneurysms (IAs) implies the significance of investigating the transport and accumulation of blood substances [e.g., low-density lipoprotein (LDL), lipoprotein (a)] related to WE in IAs. In the present study, we perform numerical simulations to explore the relationships between the distribution/severity of LDL deposition on the lumen surface and the morphological characteristics of aneurysm and its adjacent arteries as well as the underlying fluid dynamic mechanisms. Bifurcation aneurysms located at the middle cerebral artery are selected as the subject of investigation and for which both idealized and patient-specific models are built. Studies on the idealized models reveal that the aneurysm–parent (AP) artery angle is more powerful than other morphological parameters [e.g., daughter–parent (DP) artery angle, nonsphericity index (NI) of aneurysm] in determining the severity of LDL deposition. A bleb (i.e., secondary sac) can enhance local LDL deposition, especially when located in an LDL deposition-prone aneurysm wall region. In patient-specific models, the dominant effect on the LDL deposition of the AP angle remains identifiable, whereas the effects of the DP angle and NI are overwhelmed by confounding factors. Enhanced LDL deposition prefers to appear in wall regions perpendicular to the intra-aneurysmal vortex centerline. In comparison with wall shear stress magnitude, the normal-to-tangential near-wall velocity ratio and particle residence time can better predict the localization of enhanced LDL deposition.

Topological Data Analysis and Use of Mapper for Cerebral Aneurysm Rupture Status Discrimination Based on 3-Dimensional Shape Analysis.

Topological data analysis (TDA), which identifies patterns in data through simplified topological signatures, has yet to be applied to aneurysm research. We investigate TDA Mapper graphs (Mapper) for aneurysm rupture discrimination. Two hundred sixteen bifurcation aneurysms (90 ruptured) from 3-dimensional rotational angiography were segmented from vasculature and evaluated for 12 size/shape and 18 enhanced radiomics features. Using Mapper, uniformly dense aneurysm models were represented as graph structures and described by graph shape metrics. Mapper dissimilarity scores (MDS) were computed between pairs of aneurysms based on shape metrics. Lower MDS described similar shapes, whereas high MDS represented shapes that do not share common characteristics. Ruptured/unruptured average MDS scores (how "far" an aneurysm is shape-wise to ruptured/unruptured data sets, respectively) were evaluated for each aneurysm. Rupture status discrimination univariate and multivariate statistics were reported for all features. The average MDS for pairs of ruptured aneurysms were significantly larger compared with unruptured pairs (0.055 ± 0.027 vs 0.039 ± 0.015, P < .0001). Low MDS suggest that, in contrast to ruptured aneurysms, unruptured aneurysms have similar shape characteristics. An MDS threshold value of 0.0417 (area under the curve [AUC] = 0.73, 80% specificity, 60% sensitivity) was identified for rupture status classification. Under this predictive model, MDS scores <0.0417 would identify unruptured status. MDS statistical performance in discriminating rupture status was similar to that of nonsphericity and radiomics Flatness (AUC = 0.73), outperforming other features. Ruptured aneurysms were more elongated ( P < .0001), flatter ( P < .0001), and showed higher nonsphericity ( P < .0001) compared with unruptured. Including MDS in multivariate analysis resulted in AUC = 0.82, outperforming multivariate analysis on size/shape (AUC = 0.76) and enhanced radiomics (AUC = 0.78) alone. A novel application of Mapper TDA was proposed for aneurysm evaluation, with promising results for rupture status classification. Multivariate analysis incorporating Mapper resulted in high accuracy, which is particularly important given that bifurcation aneurysms are challenging to classify morphologically. This proof-of-concept study warrants future investigation into optimizing Mapper functionality for aneurysm research.

Safety and effectiveness of the Woven EndoBridge (WEB) system for the treatment of wide necked bifurcation aneurysms: final 5 year results of the pivotal WEB Intra-saccular Therapy study (WEB-IT)

IntroductionThe US Woven EndoBridge Intra-saccular Therapy (WEB-IT) study is a pivotal, prospective, single arm, investigational device exemption study to evaluate the safety and effectiveness of the WEB device for the...

Numerical simulation of flow-diverting stent: comparison between branches in bifurcation brain aneurysm.

The usage of flow-diverting stents in the treatment of intracranial aneurysms is widespread due to their high success and low complication rates. However, their use is still not officially recommended for bifurcation aneurysms, as there is a risk of generating ischemic complications due to the reduced blood flow to the jailed branch. Many works utilize computational fluid dynamics (CFD) to study how hemodynamic variables respond to flow diverter placement, but few seem to use it to verify flow variation between branches of bifurcation aneurysms and to aid in the choice of the best ramification for device placement. This investigation was performed in the present work, by comparing wall shear stress (WSS) and flowrates for a patient-specific scenario of a middle cerebral artery (MCA) aneurysm, considering device placement on each branch. A secondary objective was to follow a methodology that provides fast results, envisioning application to daily medical practice. The device was simplified as a homogeneous porous medium, and extreme porosity values were simulated for comparison. Results suggest that stent placement on either branch is both safe and effective, significantly reducing WSS and flow into the aneurysm while maintaining flow to the different ramifications within acceptable thresholds.

Woven Endobridge embolization: Indications and innovation.

The treatment of intracranial aneurysms has seen incredible advancements over the last few decades. Long-term occlusion of wide-neck bifurcation aneurysms remains technically challenging. The Woven Endobridge (WEB) embolization device is innovative in its construction and uses. The design of the device has evolved over the last decade. Pre-clinical and clinical trials are ongoing and continue to inform the development of intrasaccular flow-diverting devices. The WEB device is currently approved by the U.S. Food and Drug Administration (FDA) for treating wide-neck aneurysms. The safety and efficacy of the WEB device have yielded promising clinical results that may have additional indications. This review aims to discuss the development of the WEB device and the current state of the WEB device in the treatment of wide-neck aneurysms. We also summarize ongoing clinical studies and potential innovative uses.

Decision-making tree for optimal Woven EndoBridge device sizing with ideal Woven EndoBridge-aneurysm volume (iWAVe) ratio

PurposeOptimal size selection is important for successful Woven EndoBridge (WEB) treatment. Conventional recommendations for WEB sizing based on aneurysm width and height sometimes require device exchange. We aimed to design a novel volume-based parameter, the ideal WEB-aneurysm volume (iWAVe) ratio, for optimal WEB sizing. MethodsConsecutive patients who underwent WEB treatment for wide-neck bifurcation aneurysms between January 2021 and May 2022 were retrospectively reviewed. Aneurysm volume was automatically calculated using software. We measured the aneurysm volume based on the expected position of the device within the aneurysm. The WAVe ratio was defined as the ratio of the aneurysm volume to WEB volume. We dichotomized aneurysms treated with a successful sizing or unsuccessful sizing for WEB (successful group and unsuccessful group, respectively). ResultsThirty-five patients were eligible for study enrollment. Ten patients (28.6%) needed to exchange the WEB on the first attempt and required another WEB on the second attempt resulting in deployment success. Hence, 35 aneurysms were in the successful group and 10 were in the unsuccessful group. The median WAVe ratio was 1.0 (range 0.76–1.31) in the successful group and 1.27 (0.58–1.89) in the unsuccessful group. Using logistic regression, iWAVe ratio was from 0.90–1.16 to secure a >80% probability of success by the 95% lower confidence limit. The sensitivity and specificity of the iWAVe ratio for optimal size selection on the first attempt were 0.60 and 1.00, respectively. ConclusionDecision-making based on aneurysm width and the iWAVe ratio could promote optimal WEB sizing.

Woven EndoBridge system for wide-necked bifurcation aneurysms treatment: Preliminary results of the first center in Southeast Asia

This study reports the initial results of wide-necked bifurcation aneurysms treated with Woven EndoBridge (WEB) system at one of the first centers in Southeast Asia from April 2019 to June 2022. A total of 12 patients (50% female, median age of 66) with 12 aneurysms (9 unruptured and 3 ruptured) were recruited. The aneurysms were located in the basilar apex (4 patients), anterior communicating artery (4 patients), middle cerebral artery (3 patients), and posterior cerebral artery (1 patient). The average aneurysm size was 6.3mm (range 4.8 - 8.0mm) with mean dome to neck ratio of 1.2 and mean neck size of 5.4 mm (range 3.7 - 6.9mm). The technique was successful in all cases (100%) without any adjunctive devices. No intraoperative rupture occurred. Thromboembolic complications that occurred in two patients resulted in death in 1 patient (accompanied by retroperitoneal bleeding) (1/12, 8.3%) and moderate disability in 1 patient (1/12, 8.3%). The MRI follow-up at 3 months showed complete occlusion in 6 aneurysms (6/11, 54.5%) and neck remnant in 5 aneurysms (5/11, 45.5%). The study demonstrated that the WEB system alone was feasible to treat both ruptured and unruptured wide-necked bifurcation aneurysms. This device seems to be a promising tool for the treatment of complex wide-necked bifurcation aneurysms.

"Stump Patch Rescue" Reclipping Using Divided Origin of Temporal M2 in a Recurrent Reruptured Bilobed Middle Cerebral Artery Bifurcation Aneurysm: 2-Dimensional Operative Video.

Wu, Eva M. MD; Sun, Matthew Z. MD; Starke, Robert M. MD; Morcos, Jacques J. MD Author Information

In vitro flow diversion effect of the ReSolv stent with the shelf technique in a bifurcation aneurysm model

BackgroundFlow-diverting stents are not currently indicated for the treatment of bifurcation aneurysms, and some case series have demonstrated low occlusion rates, possibly due to a lack in neck coverage. The...

Long-Term Follow-Up of Cerebral Aneurysms Completely Occluded at 6Months After Intervention with the Woven EndoBridge (WEB) Device: a Retrospective Multicenter Observational Study.

The Woven EndoBridge (WEB) device has been widely used to treat intracranial wide neck bifurcation aneurysms. Initial studies have demonstrated that approximately 90% of patients have same or improved long-term aneurysm occlusion after the initial 6-month follow up. The aim of this study is to assess the long-term follow-up in aneurysms that have achieved complete occlusion at 6months. We also compared the predictive value of different imaging modalities used. This is an analysis of a prospectively maintained database across 13 academic institutions. We included patients with previously untreated cerebral aneurysms embolized using the WEB device who achieved complete occlusion at first follow-up and had available long-term follow-up. A total of 95 patients with a mean age of 61.6 ± 11.9years were studied. The mean neck diameter and height were 3.9 ± 1.3mm and 6.0 ± 1.8mm, respectively. The mean time to first and last follow-up was 5.4 ± 1.8 and 14.1 ± 12.9months, respectively. Out of all the aneurysms that were completely occluded at 6months, 84 (90.3%) showed complete occlusion at the final follow-up, and 11(11.5%) patients did not achieve complete occlusion. The positive predictive value (PPV) of complete occlusion at first follow was 88.4%. Importantly, this did not differ between digital subtraction angiography (DSA), magnetic resonance angiography (MRA), or computed tomography angiography (CTA). This study underlines the importance of repeat imaging in patients treated with the WEB device even if complete occlusion is achieved short term. Follow-up can be performed using DSA, MRA or CTA with no difference in positive predictive value.

Woven EndoBridge Device Migration and Microsnare Retrieval Strategy: Single Institutional Case Reports with Technical Video Demonstration.

The Woven EndoBridge (WEB) (MicroVention/Terumo) device is a treatment option for wideneck bifurcation aneurysms. An uncommon adverse effect is WEB device migration. While certain bailout strategies for WEB recovery have been described, there is still a paucity of information on optimal strategies to maximize both short and long-term post-operative outcomes. We add 2 cases at our institution to the existing literature of WEBectomy in the setting of complicated intracranial aneurysm treatment. We discuss the long-term imaging outcomes with additional fluoroscopy video demonstrating our technique. Our findings reflect a clear benefit for the use of the Amplatz GooseneckTM microsnare (Medtronic) device as a means of WEB recovery, coupled with potential stent-assisted WEB embolization to remove the aneurysm from the parent circulation, while minimizing recurrence and thromboembolic complications.

Need for Y-stenting in stent-assisted coiling of wide-neck bifurcation aneurysms

Background and PurposeStent-assisted coiling of wide neck bifurcation aneurysms in the anterior communicating segment and basilar tip region can be performed with varying stent configurations, including single stenting or Y-stenting. Y-stenting requires two stents and thus incurs greater cost and procedural complexity than single-stent constructs. The influence of first stent type on the need for Y-stenting remains unknown. Materials and MethodsClinical and angiographic data were retrospectively obtained for patients that underwent stent-assisted coiling for basilar tip or anterior communicating aneurysms at a high-volume center. Patients were included in this study if stent-assisted coiling was performed using Neuroform Atlas or LVIS Jr stents. A multivariate binary logistic regression was performed to measure the influence of first stent type on the need for Y-stenting. ResultsStent-assisted coiling was used to treat 82 aneurysms in 81 patients during the study period, and Y-stenting was performed in 18.3% (15/82) of cases. In multivariate logistic regression analysis, use of LVIS Jr. as the first stent did not significantly influence the need for subsequent Y-stenting after controlling for aneurysm morphology (OR 0.65, 95% CI 0.18–2.43). ConclusionControlling for aneurysm morphology and location, the use of Y-stenting for stent-assisted coiling was not independently influenced by the choice of LVIS Jr or Neuroform Atlas as the first stent. A larger cohort may reveal differences between these two stents, particularly for aneurysms with large neck sizes.