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Background The flow diversion treatment of aneurysms located distal to the Circle of Willis has recently increased in frequency. We conducted a systematic review and meta-analysis of the clinical and radiological outcomes of flow diverter (FD) embolization in treating M1 aneurysms. Methods PubMed, Web of Science, Ovid Medline, Ovid Embase, and Scopus were searched up to May 2024 using the Nested Knowledge platform. We included studies assessing the long-term clinical and radiological outcomes for M1 aneurysms. Results of FDs classified as Pipeline Embolization Devices (PED) versus other types of FDs. Angiographic occlusion rates, ischemic and hemorrhagic complications, and favorable clinic outcomes were included. All data were analyzed using R software version 4.2.2. Results Thirteen studies with 112 total patients (58 patients for PED and 54 patients for other FD devices) were included in our meta-analysis. The overall adequate (complete + near-complete) occlusion rates were 85.1%. The complete occlusion rate was higher with PED than with other FD devices (72.9% PED and 41.6% for non-PED FDs, respectively, p -value <.01). The ischemic complications were 9.9% and 9.0% for the PED and non-PED groups, respectively ( p -value = .89). The overall modified Rankin Scale 0–2 was 100% for the non-PED and 97.1% for the PED group ( p -value = .51). In-stent stenosis rate was 7.5% for PED devices compared to 2.6% in the non-PED group ( p -value = .35). Conclusions This relatively small meta-analysis showed high rates of adequate and complete occlusion in FD treatment of M1 segment aneurysms, with favorable safety profiles. PEDs were associated with higher rates of complete aneurysm occlusion compared to other types of FDs.

OBJECTIVE Fibrin deposition represents a key step in aneurysm occlusion, promoting endothelization of implants and connective tissue organization as part of the aneurysm-healing mechanism. In this study, the authors introduce a novel in vitro testing platform for flow diverters based on human fibrinogen. METHODS A flow diverter was deployed in 4 different glass models. The glass models had the same internal parent artery (4 mm) and aneurysm (8 mm) diameters with varying parent artery angulations (paraophthalmic, sidewall, bifurcation, and slightly curved models). The neck size and area were 4 mm and 25 mm 2 , respectively. Human fibrinogen (330 mg/dl) was circulated within the glass models at varying flow rates (0, 3, 4, and 5 ml/sec) with or without heparin, calcium chloride, and thrombin for as long as 6 hours or until complete fibrin coverage of the flow diverter’s neck was achieved. Aneurysm neck coverage was defined as macroscopic fibrin deposition occluding the flow diverters’ pores. Flow characteristics after flow diverter deployment were assessed with computational fluid dynamics analysis. The effects of flow rates, heparin, calcium chloride, and thrombin on fibrin deposition rates were tested using 1-way ANOVA and the Tukey test. RESULTS A total of 84 replicates were performed. Human fibrin did not accumulate on the flow diverter stents under static conditions. The fibrin deposition rate on the aneurysm neck was significantly greater with the 5 ml/sec flow rate as compared to 3 ml/sec for all models. The paraophthalmic model had the highest inflow velocity of 48.7 cm/sec. The bifurcation model had the highest maximum shear stress (SS) and maximum normalized shear stress values at the device cells at 843.3 dyne/cm 2 and 35.1 SS/SS inflow , respectively. The fibrin deposition rates of the paraophthalmic and bifurcation models were significantly higher than those of sidewall and slightly curved models for all additive or flow rate comparisons (p = 0.001 for all comparisons). The incorporation of thrombin significantly increased the fibrin deposition rates across all models (p = 0.001 for all models). CONCLUSIONS Rates of fibrin deposition varied widely across different configurations and additive conditions in this novel in vitro model system. Fibrin accumulation started at the aneurysm inflow zone where flow velocity and shear stress were the highest. The primary factors influencing fibrin deposition included flow velocities, shear stress, and the addition of thrombin at a physiological concentration. Further research is needed to test the clinical utility of fibrinogen-based models for patient-specific aneurysms.

The New Zealand rabbit elastase-induced arterial aneurysm of the right common carotid artery remains a widely used model for assessing the effectiveness and safety of new neuroendovascular devices.1 This model offers a simple and reliable platform for pre-clinical in vivo investigations, crucial for comprehending the biological processes underlying aneurysm healing after endovascular treatment.2 Notably, the induced aneurysm exhibits morphological, hemodynamic, and histological characteristics similar to human intracranial aneurysms. The creation of the aneurysm is performed using open and endovascular techniques. Each step of the procedure requires a meticulous and controlled gesture to ensure reproducibility of the aneurysm and minimize animal misuse. In video 1 we present a step-by-step procedural guide for aneurysm creation and follow-up. We hope this resource will help in promoting this model and provide useful guidance for researchers in the field. Video 1 Surgical procedure of creating elastase-induced aneurysms in rabbits.

OBJECTIVE Fibrin deposition is integral to thrombus formation and wound healing. The role of fibrin deposition and subsequent metabolism following flow diversion for aneurysm treatment remains poorly characterized. This study aimed to evaluate the role of fibrin in early thrombus organization after flow diverter treatment. METHODS Thirty-five elastase-induced aneurysms were induced in New Zealand white rabbits and subjected to endoluminal flow diversion treatment. The device-bearing arteries were harvested at 1, 3, and 6 months postimplantation and processed for histopathological examination, including a modified picro-Mallory stain (Carstairs method) to visualize fibrin and platelets, immunohistochemical targeting of smooth muscle actin (SMA), and H&E staining for conventional morphological evaluation. Quantitative analysis of tissue components was carried out using the Orbit Image Analysis software. The samples were also assessed qualitatively to investigate the morphology and location of fibrin and other thrombus components within the intra-aneurysmal thrombi. Statistical analyses were conducted using R software version 4.3.1. RESULTS Fibrin constituted 27.9% of the thrombus tissue within the aneurysm sac for aneurysms harvested at 1 month, and this rate was significantly lower in the 3-month group (10.2%, p = 0.018). The proportion of blood cells within the sac was also notably higher in the 1-month group compared with other time points. The primary tissue filling the dome at 1 month (14/15, 93%) was an unorganized thrombus primarily composed of fibrin, platelets, and red blood cells. Conversely, aneurysms harvested at 1 month had the lowest collagen level (25.6%). However, collagen became the dominant tissue component within the aneurysm sac, accounting for 71.8% of tissue in the 3-month group (p = 0.007). There were no differences observed among the examined components between the 3-month and 6-month groups. On qualitative analysis, collagen-producing SMA-positive myofibroblasts were located near or in between fibrin molecules. Healed aneurysms exhibited myofibroblasts, collagen, and a well-organized fibrin network on the aneurysm neck. In contrast, unhealed aneurysms displayed a poorly organized fibrin network with scattered myofibroblasts at the neck area. CONCLUSIONS These findings indicate that fibrin plays a foundational role in the gradual occlusion of aneurysms after flow diverter treatment. Endovascular approaches that enhance fibrin accumulation could potentially improve aneurysm occlusion rates. Further research is needed to establish the precise role of fibrin in aneurysm occlusion.

Background Wide neck bifurcation aneurysms (WNBAs) are a subtype of aneurysms that are especially complex to treat. We aim to conduct a systematic review and meta-analysis to synthesize the available literature on the safety and efficacy of employing endovascular clip system (eCLIPs) in the treatment of WNBAs. Methods We report this study in accordance to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2020 guidelines. PubMed, Embase, Web of Science, and Scopus were queried for this review. Screening and extraction were performed by at least two authors to ensure accuracy and completeness, and a senior author arbitrated any discrepancies. All data were analyzed using R software version 4.3.0. and random-effects model. Results Four studies were finally included, of which three were prospective and one was retrospective. Successful adjunctive coiling occurred in 91.38% (95% CI = 70.71–97.9) of cases and overall technical success was achieved in 88.61% (95 CI = 75.54–95.15) of cases. The pooled complete occlusion (Raymond-Roy Class I) was 50.65% (95% CI = 39.63–61.60) and adequate occlusion (Raymond-Roy Class I/II) was 84.42% (95% CI = 74.53–90.93). Thrombo-embolic complication had a pooled rate of 1.22% (95% CI = 0.17–8.15), retreatment rate was 6.10% (95% CI = 2.56–13.83), and mortality reported in 3.66% (95% CI = 1.18–10.74) of patients. Conclusion The use of eCLIPs may be a safe and efficacious treatment for WNBAs. Future randomized controlled trials are needed for further validation of the findings.

Introduction Background: The Woven Endo‐Bridge (WEB) device is an intrasaccular device being used to secure intracranial aneurysms through the endovascular approach. The WEB is commonly used for wide‐neck aneurysms. There are no comprehensive studies to assess the low‐profile device WEB 17 so far. Although, some single studies have reported their early experience using the device. We plan to provide a comprehensive assessment of the early center experience using the WEB 17 device to secure intracranial aneurysms. Objective: To provide an overview of the early‐center experience of the 0.017‐inch endovascular Woven EndoBridge device (WEB‐17) device. Methods A systematic review and meta‐analysis were conducted following the PRISMA recommendations. On April 15, 2023, we searched for eligible papers in Pubmed, Web of Science (ISI), Scopus, and Embase databases. The meta‐analysis was done using R software version 4.3.0. and the "meta" package. Pooled prevalence (%) and their corresponding 95% confidence intervals (CI), random‐effects model based and the generalized linear mixed models (GLMMs) method. On the presence of multiple follow‐up points, we included the last available in the analysis. Complete occlusion was defined as Raymond–Roy occlusion classification (RROC) class I, and adequate occlusion was defined as RROC class I or II. Results Seven studies were finally included following the double‐reviewer screening of the retrieved literature. The patients' mean age ranged from 52.5±13.8 to 62.0±9.5 years, and 71.0% were females. The mean follow‐up duration ranged from 6±2.25 months to 11.6±4. Technical success was achieved in 98.34% (95% CI= 96.72‐99.17) of the cases, while adjunctive devices were used in 4.97% (95% CI= 1.60‐14.39) of them (Figure 1). The complete occlusion rate was 72.54% (95% CI= 63.44‐80.08) (Figure 2), while the adequate occlusion rate was 94.41 (95% CI= 88.17‐97.46) (Figure 3). There was no significant heterogeneity in all pooled outcomes. Conclusion The early experience of the device shows an efficacy profile comparable with the currently available devices in treating intracranial aneurysms.

Introduction Cerebral sinus venous thrombosis (CSVT) has traditionally been treated medically with systemic anticoagulation. Recent advances in endovascular therapy (EVT) may represent an alternative treatment to medical therapy for CSVT. We conducted a systematic review and meta‐analysis to evaluate the use of EVT for CSVT. Methods We conducted a systematic literature review using PubMed, Embase, Scopus, and Web of Science. We included studies that reported outcomes following EVT for CSVT. The primary outcome of interest was rate of modified Rankin Scale (mRS) 0‐2. Secondary outcomes of interest were rates of complete, partial, and failed recanalization, mortality, and new or expansion of hematoma. We calculated pooled rates (%) and their corresponding 95% confidence intervals (CI). Results Thirty‐eight studies with 682 patients were included. Rate of mRS 0‐2 was 82.6% (95% CI, 75.3%‐88.0%). Rate of complete recanalization was 60.9% (95% CI, 49.1%‐71.5%), rate of partial recanalization was 34.2% (95% CI, 24.1%‐45.9%), and rate of failed recanalization was 5.4% (95% CI, 3.1%‐9.2%). Rate of mortality was 6.7% (95% CI, 4.1%‐10.8%) and rate of new or expansion of hematoma was 5.1% (2.9%‐8.8%). Conclusion In this systematic review and meta‐analysis, EVT for CSVT was associated with favorable rates of mRS 0‐2 and recanalization. Furthermore, EVT was associated with a promising safety profile. Future prospective, comparative studies are warranted to assess EVT for CSVT.

Background Mechanical thrombectomy (MT) is a safe and effective treatment option for acute ischemic stroke due to large vessel occlusion. To investigate differences in outcomes between patients receiving left-sided and right-sided MT, we performed a systematic review and meta-analysis. Methods A systematic literature review was performed using Embase, PubMed, Scopus, and Web of Science databases. Additional literature was searched for manually. Studies reporting safety and efficacy metrics for MT were included. Data regarding the modified Rankin scale (mRS), thrombolysis in cerebral infarction (TICI), symptomatic intracranial hemorrhage (sICH), and 90-day mortality were included. A random-effects model was used to calculate pooled odds ratios (ORs), mean differences (MDs), and 95% confidence intervals (CIs). Results The literature search yielded 13 reports consisting of 19 studies ranging from 98 to 5590 patients. Patients presenting with left-sided stroke had a National Institutes of health stroke scale score 2.89 greater than patients presenting with right-sided stroke (MD = 2.89; 95% CI = 2.09–3.68; P -value < 0.001). There were no differences between left-sided and right-sided MT patients for mRS 0–2 (OR = 0.94; 95% CI = 0.85–1.04; P -value = 0.224), TICI 2b–3 (OR = 1.05; 95% CI = 0.88–1.25; P -value = 0.598), sICH (OR = 0.83; 95% CI = 0.61–1.14; P -value = 0.255), or 90-day mortality (OR = 1.06; 95% CI = 0.84–1.33; P -value = 0.610). Conclusions There does not appear to be a difference in outcomes for patients undergoing left-sided or right-sided thrombectomy.

Abstract Background: Mechanical thrombectomy (MT) has revolutionized the treatment of acute ischemic stroke (AIS) due to large vessel occlusion (LVO), but its efficacy and safety in medium vessel occlusion (MeVO) remain less explored. This multicenter, retrospective study aims to investigate the incidence and clinical outcomes of vessel perforations (confirmed by extravasation during an angiographic series) during MT for AIS caused by MeVO. Methods: Data were collected from 37 academic centers across North America, Asia, and Europe between September 2017 and July 2021. A total of 1373 AIS patients with MeVO underwent MT. Baseline characteristics, procedural details, and clinical outcomes were analyzed. Results: The incidence of vessel perforation was 4.8% (66/1373). Notably, our analysis indicates variations in perforation rates across different arterial segments: 8.9% in M3 segments, 4.3% in M2 segments, and 8.3% in A2 segments (p = 0.612). Patients with perforation had significantly worse outcomes, with lower rates of favorable angiographic outcomes (TICI 2c-3: 23% vs 58.9%, p &lt; 0.001; TICI 2b-3: 56.5% vs 88.3%, p &lt; 0.001). Functional outcomes were also worse in the perforation group (mRS 0–1 at 3 months: 22.7% vs 36.6%, p = 0.031; mRS 0–2 at 3 months: 28.8% vs 53.9%, p &lt; 0.001). Mortality was higher in the perforation group (30.3% vs 16.8%, p = 0.008). Conclusion: This study reveals that while the occurrence of vessel perforation in MT for AIS due to MeVO is relatively rare, it is associated with poor functional outcomes and higher mortality. The findings highlight the need for increased caution and specialized training in performing MT for MeVO. Further prospective research is required for risk mitigation strategies.

ImportanceEndovascular thrombectomy (EVT) is standard treatment for acute ischemic stroke (AIS) due to large-vessel occlusion (LVO), but optimal post-EVT blood pressure (BP) control remains debated.ObjectiveTo assess the association of different systolic BP targets following EVT with functional outcomes, mortality, and complications in patients with AIS due to LVO.Data SourcesSystematic review and meta-analysis of databases (PubMed, Embase, Web of Science, Scopus, and Cochrane Library) to September 8, 2023.Study SelectionInclusion criteria consisted of randomized clinical trials examining post-EVT management of systolic BP in patients with AIS and LVO comparing intensive vs conventional targets. Nonrandomized studies, observational studies, noninterventional trials, meeting abstracts, duplicate studies, studies with overlapping data, and non–English language studies were excluded. Two authors independently applied these criteria through a blinded review, with discrepancies resolved through consensus. The risk of bias in the included studies was assessed using the revised tool for assessing risk of bias in randomized trials.Data Extraction and SynthesisThis study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) reporting guideline. Three authors extracted data regarding study characteristics, baseline patient data, and outcomes of interest. The pooled data were analyzed using a random-effects meta-analysis.Main Outcomes and MeasuresRates of functional independence, 90-day mortality, symptomatic intracranial hemorrhage, and hypotensive events.ResultsA total of 4 randomized clinical trials with 1571 initially enrolled patients were included in the analysis. Lower functional independence rates were observed in the intensive control group (relative risk [RR], 0.81 [95% CI, 0.67-0.98]). No significant differences were found in 90-day mortality (RR, 1.18 [95% CI, 0.92-1.52]), symptomatic intracranial hemorrhage (RR, 1.12 [95% CI, 0.75-1.67]), or hypotensive events (RR, 1.80 [95% CI, 0.37-8.76]). There was minimal heterogeneity among the studies included in the functional independence outcome (I2 = 13% and τ2 = 0.003), which was absent among other outcomes (I2 = 0 and τ2 = 0).Conclusions and RelevanceThese findings suggest that intensive post-EVT BP reduction does not yield benefits and may carry risks. While awaiting the results of additional ongoing trials, a conservative BP management strategy after endovascular recanalization is favored in daily practice.