Flow diversion with hydrophilic polymer coating with prasugrel as single antiplatelet therapy in the treatment of acutely ruptured intracranial aneurysms: a multicenter case series, complication and occlusion rates.

BACKGROUND: This study reports a multicenter experience of using hydrophilic polymer-coated (HPC) flow diverters with prasugrel single antiplatelet therapy to treat ruptured aneurysms with subarachnoid hemorrhage (SAH). METHODS: Patients treated for intracranial aneurysms within 30 days after SAH with a p64/p48 MW HPC flow diverter were prospectively identified. Clinical presentation and outcomes, periprocedural and postprocedural complications, and degree of occlusion at follow-up were evaluated. RESULTS: A total of 84 patients were treated in 88 sessions (54.5% women; mean age 53.3 years). Four patients (4.7%) experienced flow diverter-dependent complications. No cases of aneurysm re-rupture or hemorrhagic complications related to antiplatelet therapy were recorded. Immediate complete occlusion was achieved in 27.4% of cases (23/84). The rate of complete occlusion among survivors was 83% in early follow-up, 90.2% in mid-term follow-up, and 92.3% in the latest possible follow-up. CONCLUSION: p64/p48 MW HPC flow diverters with prasugrel single antiplatelet therapy were associated with safety from aneurysm re-rupture and high occlusion rates at medium- and long-term follow-up in managing ruptured aneurysms. Adequate management of single antiplatelet therapy with prasugrel is crucial, particularly with higher doses than usual, to avoid both ischemic and hemorrhagic complications.

Neurological outcomes of flow-diverter stent placement for middle cerebral artery aneurysms, with reference to the effects of argatroban on ischemic events: patient series.

BACKGROUND: A systematic review and meta-analysis of flow-diverter stents (FDSs) for the treatment of middle cerebral artery (MCA) aneurysms reported concerns about ischemic complications during treatment. The authors report on the intraoperative and postoperative complications of unruptured MCA aneurysms and their control strategies at their hospital, with detailed information on the aneurysms and a review of the previous literature. OBSERVATIONS: Intraoperative and perioperative in-stent thrombus occlusion occurred in 3 (37.5%) of the 8 patients evaluated. In cases with in-stent thrombus formation, rapid administration of 10 mg argatroban led to improvement in blood flow, as seen on angiography. Only 1 patient (12.5%) had a symptomatic stroke postoperatively. This patient was admitted for rehabilitation and drug therapy but was discharged from the hospital 10 days postoperatively with a modified Rankin Scale (mRS) score of 1. The patient had an mRS score of 0 at 90 days after surgery and at the last observation. LESSONS: Ischemic complications require attention during FDS treatment for MCA aneurysms. The use of argatroban in cases of in-stent thrombosis may contribute to a good neurological prognosis. https://thejns.org/doi/10.3171/CASE24237.

Safety and efficacy of flow redirection endoluminal device (FRED) for treatment of intracranial aneurysm; A systematic review and meta-analysis.

BACKGROUND: Previous research has shown promising results for treating intracranial aneurysms (IAs) with a flow redirection endoluminal device (FRED). In this systematic review and meta-analysis, we aimed to assess the safety and efficacy of this device by providing pooled estimates using the data from previous studies. METHODS: A systematic literature search of Web of Sciences, PubMed, Scopus, and Embase was performed until October 8th, 2023. After selecting the final articles, relevant data were extracted. Parameters relating to safety and efficacy were pooled using STATA software. Heterogeneity was assessed using I-squared and Cochran's Q. Funnel plots and Egger's regression methods were used to evaluate publication bias. Sensitivity analysis was also performed using the leave-one-out method. RESULTS: The data of 37 studies were used for meta-analysis. The rates of immediate adequate occlusion and complete occlusion were 0.51 (95% CI: 0.31-0.71) and 0.34 (95% CI: 0.16-0.53), respectively, while the rates of the adequate and complete occlusion at the latest follow-up were 0.90 (95% CI: 0.84-0.94) and 0.75 (95% CI: 0.65-0.84), respectively. The periprocedural complications rate was 0.04 (95% CI: 0.03-0.06), and the overall complications rate was 0.12 (95% CI: 0.09-0.15). The rate of good functional outcome was 0.99 (95% CI: 0.99-1.00) and the successful implantation rate was 1.00 (95% CI: 1.00-1.00). There was substantial heterogeneity among the reports for most of the evaluated parameters. CONCLUSION: FRED had high safety and efficacy in treating IAs, as evidenced by its high occlusion and low complication rates.

Treatment of medullary aneurysm in the collateral circulation with a flow diverter: A case report.

INTRODUCTION AND IMPORTANCE: Spinal aneurysms rarely occur in the collateral circulation of the vertebral artery (VA). These aneurysms are difficult to treat. A flow diverter (FD) can be a therapeutic option. CASE PRESENTATION: A 62-year-old man suffered subarachnoid hemorrhage. His Hunt-Hess scale classification was grade II. Digital subtraction angiography (DSA) revealed that the bilateral distal VAs were occluded, there were two flow-related aneurysms in the collateral circulation of the first radicular artery of the VA, and there was a dissecting aneurysm at the origin of the posterior inferior cerebellar artery (PICA). The FD covered the PICA dissecting aneurysm, and the first radicular artery originated in the VA. Postoperatively, computed tomography angiography revealed a patent PICA and regression of the aneurysm in the collateral circulation. At the one-month follow-up, he showed good recovery and was therefore allowed to return to work. Follow-up DSA confirmed the regression of the aneurysms. However, the intracranial VA and PICA were unexpectedly occluded. CLINICAL DISCUSSION: It is difficult to catheterize aneurysms in the collateral circulation to perform coiling. It is also dangerous to embolize such aneurysms with a liquid embolic agent. After FD deployment to cover the origin of the parent artery, the hemodynamic stress of the aneurysm decreases, and the aneurysm can regress. CONCLUSION: Aneurysms in the collateral circulation were not accessible. FD deployment in the parent artery to cover the origin of the feeding artery of the collateral circulation is feasible for treating such aneurysms.

Microsurgical and endovascular treatment of large and giant aneurysms of the anterior circulation: A systematic review.

Introduction: Large and Giant intracranial aneurysms (LGIAs) have become the paradigm for which endovascular techniques do not provide satisfactory results. Yet, microsurgery is followed by non-negligible rates of morbimortality. This scenario may have changed since the introduction of flow-diversion devices. Research question: Contemporary and standardised revision on microsurgical and endovascular results, with emphasis on anterior circulation LGIAs. Materials and methods: A systematic literature search was conducted in two databases (PubMed and Embase) on treatment outcomes of LGIAs of the anterior circulation, after the introduction of flow-diverters 2008/01/01, till 2023/05/20. Small case series (<5 cases), series including >15% of posterior circulation aneurysms, and studies not reporting clinical and/or angiographic outcomes were excluded. Results: 44 relevant studies (observational cohorts) were identified, including 2923 LGIAs predominantly from anterior circulation. Mean follow-up 22 (±20) months. 1494 (51%) LGIAs were treated endovascularly and 1427 (49%) microsurgically. According to the random effects model, pooled rates of favourable clinical outcomes were 85.8% (CI 95% 82.6-88.4), complete occlusion 69.4% (CI 95% 63.7-7.46), complications 19.6% (CI 95%16-23.9) and mortality 5.6% (CI 95% 4.4-7.1). Focusing on type of treatment, occlusion rates are higher with microsurgical (842/993, 85% vs 874/1,299, 67%), although good outcomes are slightly more frequent with endovascular (1045/1,135, 92% vs 1120/1,294, 87%). Discussion and conclusions: According to contemporary data about occlusion rates, functional outcomes, and complications, primary or secondary treatment of LGIAs of the anterior circulation seems justified. Microsurgical occlusion rates are higher in LGIAs. An expert consensus on reporting complications and management strategies is warranted.

Endovascular Treatment of "Donut-Shaped" Aneurysm-A Case Series.

Background and Objectives: Partially thrombosed aneurysms represent a subset primarily found within large and giant aneurysms. The presence of an intraluminal thrombus can cause an aneurysm to present in different shapes upon angiographic examination. We present a series of five cases of "donut-shaped" aneurysms observed over the past decade at the Clinic for Neurosurgery in the University Clinical Centre of Serbia. Materials and Methods: The management of "donut-shaped" aneurysms was accomplished through endovascular interventions, employing techniques such as the deployment of flow-diverting stents or a combination of stent placement and coil embolization. Results: Four out of five patients underwent endovascular treatment, yielding positive outcomes with complete thrombosis of the aneurysms during follow-up. The fifth patient was successfully diagnosed; however, due to their deteriorating condition, treatment was not feasible. Conclusions: Given the potential life-threatening complications associated with this entity, accurate diagnosis and appropriate management are crucial. In our cohort, endovascular interventions demonstrated efficacy in the majority of cases, underscoring the significance of this approach in treating "donut-shaped" aneurysms. Nevertheless, considering the rarity of this condition, further research is justified to refine diagnostic and therapeutic strategies for these complex intracranial vascular anomalies.

In vitro evaluation of flow diverter performance using a human fibrinogen-based flow model.

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 mm2, 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/cm2 and 35.1 SS/SSinflow, 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.

Comparative Efficacy of Flow Diverter Devices in the Treatment of Carotid Sidewall Intracranial Aneurysms: a Retrospective, Multicenter Study.

BACKGROUND: The comparative efficacy and safety of first-generation flow diverters (FDs), Pipeline Embolization Device (PED) (Medtronic, Irvine, California), Silk (Balt Extrusion, Montmorency, France), Flow Re-direction Endoluminal Device (FRED) (Microvention, Tustin, California), and Surpass Streamline (Stryker Neurovascular, Fremont, California), is not directly established and largely inferred. PURPOSE: This study aimed to compare the efficacy of different FDs in treating sidewall ICA intracranial aneurysms. METHODS: We conducted a retrospective review of prospectively maintained databases from eighteen academic institutions from 2009-2016, comprising 444 patients treated with one of four devices for sidewall ICA aneurysms. Data on demographics, aneurysm characteristics, treatment outcomes, and complications were analyzed. Angiographic and clinical outcomes were assessed using various imaging modalities and modified Rankin Scale (mRS). Propensity score weighting was employed to balance confounding variables. The data analysis used Kaplan-Meier curves, logistic regression, and Cox proportional-hazards regression. RESULTS: While there were no significant differences in retreatment rates, functional outcomes (mRS 0-1), and thromboembolic complications between the four devices, the probability of achieving adequate occlusion at the last follow-up was highest in Surpass device (HR: 4.59; CI: 2.75-7.66, p < 0.001), followed by FRED (HR: 2.23; CI: 1.44-3.46, p < 0.001), PED (HR: 1.72; CI: 1.10-2.70, p = 0.018), and Silk (HR: 1.0 ref. standard). The only hemorrhagic complications were with Surpass (1%). CONCLUSION: All the first-generation devices achieved good clinical outcomes and retreatment rates in treating ICA sidewall aneurysms. Prospective studies are needed to explore the nuanced differences between these devices in the long term.

It Is Necessary to Pay Attention to Where the Pcom Originate from the Aneurysm to Treat with FD.

Objective With the expansion of indications of flow diverter (FD) for cerebral aneurysms, FD placement for posterior communicating artery (Pcom) aneurysms has been approved. However, it is controversial whether Pcom aneurysms should be treated with FD or not. In this study, we report the outcome of FD treatment for Pcom aneurysms in Japan. Materials and Methods We retrospectively analyzed 36 patients with 38 aneurysms treated with FD placement for Pcom aneurysms between 2015 and 2021 in our hospital. We divided our cases into complete occlusion (CO) and non-CO groups. And we extracted contributing factors to CO using multivariate analysis. We also compared the complications rate among the three types of FDs. Results CO was obtained in 29 cases (79.3%), and complications were observed in 3 cases (7.9%). Multivariate analysis revealed that the type of Pcom branch from the aneurysmal dome was a significant factor contributing to CO (odds ratio: 0.0052, 95% confidence interval 0.000048-0.584, p = 0.029). In terms of complications, complication rate was significantly higher in the Flow-Redirection Endoluminal Device (FRED) group ( p = 0.0491). Conclusion The outcome for Pcom aneurysms treated by FD was acceptable. When treating, we must pay attention to where Pcom originates. Achieving CO with FD is difficult for aneurysms where the Pcom branches from the dome. Furthermore, when treating Pcom aneurysms with FRED, it is necessary to be careful about thromboembolic complications.

Bifurcation dissecting aneurysm: tips and tricks to differentiate from saccular aneurysm.

Bifurcations are a common site for saccular aneurysms, but rarely can be a site for dissecting aneurysms. Identification of these aneurysms is extremely important because the management plan depends on it. We describe a rare case of a ruptured dissecting aneurysm at the right ICA bifurcation in a pre-teen child which posed a diagnostic dilemma but ultimately was successfully managed with flow diversion.

Innovations in intracranial aneurysm treatment: a pilot study on the Choydar flow diverter.

Background: The flow diverter (FD) has emerged as a promising treatment option for intracranial aneurysms. Recently, a novel flow-diverting stent, the Choydar FD device, has been developed within our nation. Objective: To introduce the newly developed Choydar FD device and present our preliminary clinical experience with its application in the treatment of intracranial aneurysms. Methods: A total of 23 patients with 23 unruptured intracranial aneurysms, comprising 20 (87.0%) aneurysms located at the internal carotid artery and 3 (13.0%) at the vertebral artery, were treated with the Choydar FD device between December 2021 and April 2022. Patient baseline data, clinical and angiographic outcomes were collected and analyzed. Results: The Choydar FD device was successfully deployed in all patients (100%), with 18 aneurysms (78.3%) additionally treated with coils. One patient experienced an ischemic event with sensory disturbance during the perioperative period. At the 1-year follow-up, all patients demonstrated good clinical outcomes. Of the 23 aneurysms with available angiographic follow-up, 22 (95.7%) achieved complete occlusion, and one patient exhibited in-stent stenosis without neurological deficits. Conclusion: The initial clinical results of the Choydar FD device are encouraging, and it appears to be a useful option for treating intracranial aneurysms with acceptable efficacy and safety. Future studies with larger sample sizes and longer follow-up durations are warranted to validate these findings.

Pipeline Vantage Embolization Device for the treatment of intracranial aneurysms: A systematic review and meta-analysis.

OBJECTIVE: The Pipeline Vantage Embolization Device (PVED) is a novel coated flow diverter with reduced wire diameters to improve neoendothelialization and stent porosity. This systematic review evaluates the safety and efficacy of the PVED based on the current literature. METHODS: Following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, a thorough literature search was conducted using PubMed, EMBASE, and Cochrane. The random effects model was used to calculate estimates with major neurological complications within 30 days of treatment as the primary safety endpoint and ≤1-year complete occlusion rate as the primary efficacy endpoint. RESULTS: Six single-arm studies (5 retrospective, 1 prospective) with 392 patients and 439 aneurysms (6.8% ruptured) were included. Antiplatelet regimens varied, but dual antiplatelet therapy was administered in the majority. The pooled technical success rate was 99.0% (95%CI, 98.0%-100%) with an average of 1.2 devices implanted per procedure. Balloon angioplasty was performed in 17.0% (95%CI, 6.4-27.6%) and adjunctive coiling in 28.0% (95%CI, 17.8-38.2%), with significant heterogeneity for both variables. Pooled estimates for major neurological complications were 3.5% (95%CI, 1.7%-5.2%) with total ischemic events in 4.1% (95% CI, 1.6%-6.6%) and hemorrhagic events in 1.0% (95% CI, 0.0%-1.9%). The rate of complete angiographic occlusion was 75.7% (95%CI, 70.7%-80.6%) at a mean follow-up of 7 months, with in-stent stenoses in 8.1% (95%CI, 4.5%-11.8%). CONCLUSIONS: The safety and efficacy profile of the PVED appears comparable to competing devices, with potentially fewer complications than first-generation flow diverters. Long-term and comparative studies are needed to further confirm these results.

Pipeline versus non-pipeline flow diverter treatment for M1 aneurysms: A systematic review and meta-analysis.

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.

Impact of Various Non-Contrast-Enhanced MRA Techniques on Lumen Visibility in Vascular Flow Models with a Surpass Evolve Flow Diverter.

BACKGROUND: Silent MRA has shown promising results in evaluating the stents used for intracranial aneurysm treatment. A deep learning-based denoising and deranging algorithm was recently introduced by GE HealthCare. The purpose of this study was to compare the performance of several MRA techniques regarding lumen visibility in silicone models with flow diverter stents. METHODS: Two Surpass Evolve stents of different sizes were implanted in two silicone tubes. The tubes were placed in separate boxes in the straight position and in two different curve configurations and connected to a pulsatile pump to construct a flow loop. Using a 3.0T MRI scanner, TOF and silent MRA images were acquired, and deep learning reconstruction was applied to the silent MRA dataset. The intraluminal signal intensity in the stent (SIin-stent), in the tube outside the stent (SIvessel), and of the background (SIbg) were measured for each scan. RESULTS: The SIin-stent/SIbg and SIin-stent/SIv ratios were higher in the silent scans and DL-based reconstructions than in the TOF images. The stent tips created severe artefacts in the TOF images, which could not be observed in the silent scans. CONCLUSIONS: Our study demonstrates that the DL reconstruction algorithm improves the quality of the silent MRA technique in evaluating the flow diverter stent patency.

Dual Antiplatelet Non-Responder: Resistance to Clopidogrel and Ticagrelor.

Background: Dual antiplatelet therapy is often required for neurointerventional procedures, especially when a stent or flow diverter is placed in the cervical and intracranial vessels. Patients are usually started on aspirin and clopidogrel given the simplicity of the once daily regimen with reasonable cost. Unfortunately, about a third of patients do not show the desired antiplatelet response to clopidogrel and another agent needs to be introduced. Ticagrelor is a potent antiplatelet medication that has a favorable pharmacological profile and has emerged as a reliable alternative to clopidogrel in recent years. Despite ticagrelor non-responders being rare, they do exist, and identification of these patients is important. Results: A 74-year-old female was incidentally found to harbor a right posterior communicating aneurysm which was successfully treated electively with stent-assisted coiling. Platelet inhibition testing revealed non-responsiveness to Clopidogrel. Ticagrelor was initiated but the patient's platelet reactivity unit remained in the normal range. Management algorithms to maximize a patient's ticagrelor response by facilitating enteral absorption were applied but no platelet inhibition was achieved. The patient was eventually identified as a true ticagrelor non-responder. Conclusion: Resistance to antiplatelet medication can result in devastating complications with permanent neurological deficits. Ticagrelor non-responders are rare but do exist. Platelet inhibition testing should be part of the preprocedural workup for neurointerventions.

Evaluation of flow diverters for cerebral aneurysm therapy: recommendations for imaging analyses in clinical studies, endorsed by ESMINT, ESNR, OCIN, SILAN, SNIS, and WFITN.

BACKGROUND: Multiple studies and meta-analyses have described the technical and clinical outcomes in large cohorts of aneurysm patients treated with flow diverters (FDs). Variations in evaluation methodology complicate making comparisons among studies, hinder understanding of the device behavior, and pose an obstacle in the assessment of further advances in FD therapy. METHODS: A multidisciplinary panel of neurointerventionalists, imaging experts, and neuroradiologists convened with the goal of establishing consensus recommendations for the standardization of image analyses in FD studies. RESULTS: A standardized methodology is proposed for evaluating and reporting radiological outcomes of FD treatment of intracranial aneurysms. The recommendations include general imaging considerations for clinical studies and evaluations of longitudinal changes, such as neointimal lining and stenosis. They cover standards for classification of aneurysm location, morphology, measurements, as well as the assessment of aneurysm occlusion, wall apposition, and neck coverage. These reporting standards further define four specific braid deformation patterns: foreshortening, fish-mouthing, braid bump deformation, and braid collapse, collectively termed 'F2B2'. CONCLUSIONS: When widely applied, standardization of methods of measuring and reporting outcomes will help to harmonize the assessment of treatment outcomes in clinical studies, help facilitate communication of results among specialists, and help enable research and development to focus on specific aspects of FD techniques and technology.

Ruptured Vertebral Artery Dissection Treated with Endovascular Intervention.

OBJECTIVE: A retrospective study of cases of endovascular treatment of dissection of the vertebral artery with subarachnoid hemorrhage was conducted. MATERIAL AND METHODS: Data were 11 cases of vertebral artery dissecting aneurysm (VADA) among 291 consecutive subarachnoid hemorrhage patients who underwent clipping or endovascular treatment at Ota Memorial Hospital. Classified into 4 patterns based on the location of the dissection and posterior inferior cerebellar artery (PICA): pre-PICA, post-PICA, involved PICA, and non-PICA. And one of the cases had bilateral vertebral artery dissection, and computational fluid dynamics analysis was included in the study. RESULTS: Ruptured VADA occurred in 11 of the 291 patients (3.8%). Endovascular treatment was performed in 8 of these 11 patients. Postoperative diffusion-weighted imaging detected no high-intensity lesions and no postoperative ischemic complications or rebleeding occurred in any patient. In a case of bilateral VADA, computational fluid dynamics analysis of very low or high wall shear stress at the dissection, low aneurysm formation indicator, and high oscillatory shear index may be considered rupture factors. CONCLUSIONS: Treatment strategies for each branching pattern of PICA can prevent rupture and avoid ischemic complications. And prediction of the rupture side is important in patients with bilateral dissection to consider the appropriate treatment and timing.

Endovascular Treatment of Intracranial Aneurysm: The Importance of the Rheological Model in Blood Flow Simulations.

Hemodynamics in intracranial aneurysm strongly depends on the non-Newtonian blood behavior due to the large number of suspended cells and the ability of red blood cells to deform and aggregate. However, most numerical investigations on intracranial hemodynamics adopt the Newtonian hypothesis to model blood flow and predict aneurysm occlusion. The aim of this study was to analyze the effect of the blood rheological model on the hemodynamics of intracranial aneurysms in the presence or absence of endovascular treatment. A numerical investigation was performed under pulsatile flow conditions in a patient-specific aneurysm with and without the insertion of an appropriately reconstructed flow diverter stent (FDS). The numerical simulations were performed using Newtonian and non-Newtonian assumptions for blood rheology. In all cases, FDS placement reduced the intra-aneurysmal velocity and increased the relative residence time (RRT) on the aneurysmal wall, indicating progressive thrombus formation and aneurysm occlusion. However, the Newtonian model largely overestimated RRT values and consequent aneurysm healing with respect to the non-Newtonian models. Due to the non-Newtonian blood properties and the large discrepancy between Newtonian and non-Newtonian simulations, the Newtonian hypothesis should not be used in the study of the hemodynamics of intracranial aneurysm, especially in the presence of endovascular treatment.

Stent-to-vessel diameter ratio is associated with in-stent stenosis after flow-diversion treatment of intracranial aneurysms.

BACKGROUND AND PURPOSE: Flow-diversion treatment for intracranial aneurysms has been associated with the development of in-stent stenosis (ISS) for unclear reasons. We assess whether the size of the stent relative to that of the vessel (the stent-to-vessel diameter ratio, or SVR) may be predictive of the development of ISS after treatment with flow diverters. METHODS: We retrospectively reviewed patients with unruptured intracranial aneurysms who underwent flow-diversion treatment using either the Pipeline or Tubridge embolization device from September 2018 to September 2022. The relationship between SVR and ISS was analyzed. Multiple logistic regression models were used to determine the significant predictors. RESULTS: A total of 458 patients with 481 aneurysms were included. In a mean angiographic follow-up of 10.73 ± 3.97 months, ISS was detected in 68 cases (14.1 %). After adjusting for candidate variables, a higher distal SVR (DSVR) was associated with an increased risk of ISS (adjusted odds ratio [aOR] = 3.420, 95 % confidence interval [CI] = 1.182 - 9.889, p = 0.023). We conducted a subgroup analysis of the two different flow diverters to assess the effects of their individual characteristics. Our results showed a significant association between the DSVR and the incidence of ISS in both the Pipeline (aOR = 4.033, 95 % CI = 1.156-14.072, p = 0.029) and Tubridge groups (aOR = 11.981, 95 % CI=1.005-142.774, p = 0.049). CONCLUSION: A higher DSVR was associated with an increased risk of ISS. This may help neurointerventionalists select an appropriate stent size when conducting flow-diversion treatment for intracranial aneurysms.

Preclinical in vitro and in vivo results of the new silk vista flow diverter with P8RI coating.

BACKGROUND: Flow diverting stents (FDS) have transformed the treatment of intracranial aneurysms; however, their metallic structure associated with their intra-luminal positioning hamper angiographic and clinical outcomes. Therefore, there is a need to develop FDS with optimized surfaces that reduce thrombogenicity while promoting the healing process and endothelialization. METHODS: P8RI, a peptide mimicking the CD31 protein, was previously developed and grafted onto Silk Vista (SV) FDS. P8RI-SV and bare-SV were used in vitro in a blood loop model to test their hemocompatibility using human whole blood and in vivo using the rabbit elastase model for optical coherence tomography (OCT) comparisons of neointimal formation at day 5 and day 28. RESULTS: After blood loop incubation, P8RI-SV showed significant reduction in fibrin binding (p=0.004) and platelet adhesion (p=0.041) compared with bare-SV. Similarly, derivative markers measured in blood, thromboxane B2 (platelet activation) and Thrombin-Antithrombin III complexes (coagulation activation), were also significantly reduced in the P8RI-SV group (both p=0.002). In vivo, complete or near-complete occlusion was reached in all aneurysms (n=6) at day 28. Excellent rate of stent-coverage ratio was obtained at day 5 (89.3% (79.1%-98.7%)) comparable to the observation at day 28 (91.8% (79.1%-100%); p=0.44). These rates were significantly higher compared with bare-SV at day 5 (77.8% (58.3%-86.8%); p<0.001) and at day 28 (67.7% (52.6%-88.9%); p<0.0001). CONCLUSION: In vitro results confirm enhanced hemocompatibility with a significant anti-thrombotic effect of the P8RI-SV. In vivo results provide evidence of rapid neo-intimal growth reaching near-complete tissue healing as early as day 5 in a rabbit model.