Flow Diversion Research Articles

Numerical estimation of discharge coefficient for non-circular bottom intake racks

Current research presents a comprehensive numerical study on the performance of riverbed intake systems equipped with non-circular cross section racks. Three types of bottom racks, such as rhombus bars, rounded-edge rectangle bars, and circular bars, were numerically modeled using Flow3D software with different geometric and hydraulic parameter, all in super critical approaching flow in clear water condition. Subsequently, changes in diverted discharge ratio (DDR) of bottom racks and factors affecting its intensity and manner of changes, were studied using model results. The study reveals that the RNG k-ε turbulence model accurately represents the flow field around the bottom racks. The results indicated that the DDR changes are directly related to rack length changes but is inversely related to the rack slope and upstream flow discharge. Also, rhombus bars outperform circular and rounded bars, with 23.34% and 35.92% higher flow diversion, respectively, attributed to the formation of more negative pressures between bars. The main focus of the present study was on accurate and complete estimation of the diverted discharge coefficient (Cd) for racks with different bar shapes—especially non-circular bars using the results of the constructed numerical model. Proposed relations for the diverted discharge coefficient (DDC), especially for non-circular bars, were rigorously validated and showed high accuracy in predicting DDC under diverse hydraulic and geometric conditions.

A numerical simulation of the hydrothermal characteristics of a microchannel using cavities, ribs, and secondary channels

To tackle the overheating problem in microelectronic devices, microchannel heat sinks (MCHSs) are promising solutions. However, there is a need to improve their thermal performance while maintaining an acceptable pressure drop. This research investigates the effect of integrating multiple passive techniques for heat transfer enhancement, specifically examining the impact of combining triangular cavities, streamlined ribs, and oblique secondary channels (TC-SR-SC) on hydrothermal characteristics across a range of Reynolds numbers 100 to 600. By exploring the influence of each technique and their combining effects on fluid flow and heat transfer, the study aims to strike a balance between high thermal performance and low-pressure drop. Furthermore, the research also explores the thermal resistance, overall performance, entropy generation, and irreversibility of the novel design, comparing it numerically with commensurate geometries using the commercial software, FLUENT. The results reveal that the design of isosceles triangular cavities, streamlined ribs, and secondary channels combination (TC-SR-SC) achieves a maximum overall performance of 1.70 at Re = 400 due to the interruption and redevelopment of the thermal boundary layer. The presence of oblique secondary channels leads to the diversion of mainstream flow, resulting in better flow mixing between main adjacent channels. It also represents the lowest flow and heat transfer irreversibility, ultimately improving thermal performance based on the second law of thermodynamics perspective.

Flow diverters treatment planning of small- and medium-sized intracranial saccular aneurysms on the internal carotid artery via constraint-based virtual deployment.

The internal carotid artery (ICA) is a region with a high incidence for small- and medium-sized saccular aneurysms. However, the treatment relies heavily on the surgeon's experience to achieve optimal outcome. Although the finite element method (FEM) and computational fluid dynamics can predict the postoperative outcomes, due to the computational complexity of traditional methods, there is an urgent need for investigating the fast but versatile approaches related to numerical simulations of flow diverters (FDs) deployment coupled with the hemodynamic analysis to determine the treatment plan. We collected the preoperative and postoperative data from 34 patients (29 females, 5 males; mean age 55.74 ± 9.98 years) who were treated with a single flow diverter for small- to medium-sized intracranial saccular aneurysms on the ICA. The constraint-based virtual deployment (CVD) method is proposed to simulate the FDs expanding outward along the vessel centerline while be constrained by the inner wall of the vessel. The results indicate that there were no significant differences in the reduction rates of wall shear stress and aneurysms neck velocity between the FEM and methods. However, the solution time of CVD was greatly reduced by 98%. In the typical location of small- and medium-sized saccular aneurysms, namely the ICA, our virtual FDs deployment simulation effectively balances the computational accuracy and efficiency. Combined with hemodynamics analysis, our method can accurately represent the blood flow changes within the lesion region to assist surgeons in clinical decision-making.

Trajectory analysis of circulating tumor cells through contorted deterministic lateral displacement array for unruptured trapping: a simulation study

During the multistage process of cancer spread, fragments of cells branch out from the primitive tumor tissue and scatter throughout the body by blood flow stream or lymph, which are termed as circulating tumor cells (CTCs), regarded as an important biomarker for early cancer diagnosis. Deterministic lateral displacement (DLD) is one of the most efficient passive type particle isolation techniques which functions on asymmetrical laminar flow diversion around the placed microposts forming an array, based on the critical dimeter of the device. In this simulation study, complete trajectory analysis of CTCs and WBCs has been performed using COMSOL Multiphysics software with respect to the angular orientation of sample inlet channel. A simulated model of an asymmetric DLD array-based microfluidic device with latest empirical expression for critical diameter has been presented with optimized sample inlet orientation so as to maintain perfect separation efficiency of CTCs along with arrangement for unruptured trapping of CTCs and WBCs. The approximate CTC isolation efficiency was obtained above 95% for sample inlet inclinations up to 0.5°, and further tilt showed reduction in efficiency. Migration angle of CTC trajectory for the modeled device was obtained around 15° for both the sample inlet orientations leading to least intermingling of CTCs and WBCs. A smaller number of CTC–WBC interaction points was observed for clockwise sample inlet tilt compared to the anticlockwise displacement reducing possibilities of cell rupture. The shear rate around central microposts was found to be higher as well in clockwise sample inlet orientation. This simulation study establishes that sample inlet clockwise tilting of maximum around 0.5°–0.7° leads to better CTC isolation and provides better chances of unruptured trapping of cells at the designated outlets. The results of this study provide an approach toward further optimization of DLD devices' functioning and, thus, could help fabricate better DLD-based microfluidic devices for efficient trapping of CTCs.

In Situ Investigation of Foam-Induced Flow Diversion in Oil-Wet Fractured Carbonates Using Methane and Supercritical Carbon Dioxide

In Situ Investigation of Foam-Induced Flow Diversion in Oil-Wet Fractured Carbonates Using Methane and Supercritical Carbon Dioxide

Fubuki XF Long Sheath guide catheter use in neuroendovascular procedures: Institutional experience in 60 cases.

Endovascular treatment devices require compatible guide catheters to navigate complex vessels and anatomy. The Fubuki XF Long Sheath guide catheter (Fubuki XF) was developed with a 0.090-inch internal diameter with hydrophilic coating, an atraumatic rounded tip, and enhanced trackability and support with gradual shaft transition zones. We retrospectively analyzed a prospectively maintained database of neuroendovascular patients treated using Fubuki XF at our center (July 2022─May 2023). Baseline/procedural characteristics were collected. Outcomes of interest included technical success (procedure completion with Fubuki XF without alternative guide catheter use) and peri-procedural complications. This study included 60 patients (43.3% [26/60] female; mean age: 69.6 ± 9.7) presenting with stenosis (45.0% [27/60]), unruptured aneurysms (31.7% [19/60]), ruptured aneurysm (1.7% [1/60]), arteriovenous fistula (5.0% [3/60]), arteriovenous malformation (3.3% [2/60]), chronic subdural hematoma (3.3% [2/60]), stroke/emboli (6.7% [4/60]), vasospasm (1.7% [1/60]), or carotid web (5.0% [1/60]). Fubuki XF was used to deliver endovascular treatment devices for stenting (43.3% [26/60]), flow diversion (23.3% [14/60]), embolization (11.7% [7/60]), coiling (10.0% [6/60]), balloon angioplasty (10.0% [6/60]), and mechanical thrombectomy (1.7% [1/60]). The Fubuki XF tip was placed in the internal carotid artery in 38.3% (23/60) of cases. Technical success was achieved in all cases. One V1 non-flow-limiting dissection (not related to Fubuki XF) and one failed closure occurred (1.7% [1/60] each). No iatrogenic strokes or intraprocedural ruptures occurred. We used Fubuki XF to safely and effectively deliver a variety of compatible neuroendovascular devices. Fubuki XF was stable in all cases and locations, and there were no device-related complications or dissections.

Flow Diversion for Distal Aneurysms of the Posterior Circulation: A Sub-analysis of the Post-FD Registry (P1-5.008)

Flow Diversion for Distal Aneurysms of the Posterior Circulation: A Sub-analysis of the Post-FD Registry (P1-5.008)

Treatment for middle cerebral artery bifurcation aneurysms: in silico comparison of the novel Contour device and conventional flow-diverters

Endovascular treatment has become the standard therapy for cerebral aneurysms, while the effective treatment for middle cerebral artery (MCA) bifurcation aneurysms remains a challenge. Current flow-diverting techniques with endovascular coils cover the aneurysm orifice as well as adjacent vessel branches, which may lead to branch occlusion. Novel endovascular flow disruptors, such as the Contour device (Cerus Endovascular), are of great potential to eliminate the risk of branch occlusion. However, there is a lack of valid comparison between novel flow disruptors and conventional (intraluminal) flow-diverters. In this study, two in silico MCA bifurcation aneurysm models were treated by specific Contour devices and flow-diverters using fast-deployment algorithms. Computational fluid dynamic simulations were used to examine the performance and efficiency of deployed devices. Hemodynamic parameters, including aneurysm inflow and wall shear stress, were compared among each Contour device, conventional flow-diverter, and untreated condition. Our results show that the placement of devices can effectively reduce the risk of aneurysm rupture, while the deployment of a Contour device causes more flow reduction than using flow-diverters (e.g. Silk Vista Baby). Besides, the Contour device presents the flow diversion capability of targeting the aneurysm neck without occluding the daughter vessel. In summary, the in silico aneurysm models presented in this study can serve as a powerful pre-planning tool for testing new treatment techniques, optimising device deployment, and predicting the performance in patient-specific aneurysm cases. Contour device is proved to be an effective treatment of MCA bifurcation aneurysms with less daughter vessel occlusion.

The role of historical biogeography in shaping colour morph diversity in the common wall lizard.

The maintenance of polymorphisms often depends on multiple selective forces, but less is known on the role of stochastic or historical processes in maintaining variation. The common wall lizard (Podarcis muralis) is a colour polymorphic species in which local colour morph frequencies are thought to be modulated by natural and sexual selection. Here, we used genome-wide single-nucleotide polymorphism data to investigate the relationships between morph composition and population biogeography at a regional scale, by comparing morph composition with patterns of genetic variation of 54 populations sampled across the Pyrenees. We found that genetic divergence was explained by geographic distance but not by environmental features. Differences in morph composition were associated with genetic and environmental differentiation, as well as differences in sex ratio. Thus, variation in colour morph frequencies could have arisen via historical events and/or differences in the permeability to gene flow, possibly shaped by the complex topography and environment. In agreement with this hypothesis, colour morph diversity was positively correlated with genetic diversity and rates of gene flow and inversely correlated with the likelihood of the occurrence of bottlenecks. Concurrently, we did not find conclusive evidence for selection in the two colour loci. As an illustration of these effects, we observed that populations with higher proportions of the rarer yellow and yellow-orange morphs had higher genetic diversity. Our results suggest that processes involving a decay in overall genetic diversity, such as reduced gene flow and/or bottleneck events have an important role in shaping population-specific morph composition via non-selective processes.

Safety and efficacy of coated flow diverters in the treatment of ruptured intracranial aneurysms: a retrospective multicenter study

BackgroundThis multicenter study evaluated the safety and efficacy of coated flow diverters (cFDs) for the treatment of ruptured intracranial aneurysms.MethodsConsecutive patients treated with different cFDs for ruptured aneurysms under tirofiban...

Demonstration of 1000 fps High-Speed Angiography (HSA) in Pre-Clinical In-vivo Rabbit Aneurysm Models During Flow-Diverter Treatment.

High Speed Angiography (HSA) at 1000 fps is a novel interventional-imaging technique that was previously used to visualize changes in vascular flow details before and after flow-diverter treatment of cerebral aneurysms in in-vitro 3D printed models.1 In this first pre-clinical work, we demonstrate the use of the HSA technique during flow-diverter treatment of in-vivo rabbit aneurysm models. An aneurysm was created in the right common carotid artery of each of two rabbits using previously published elastase aneurysm-creation methods.2 A 5 French catheter was inserted into the femoral artery and moved to the aneurysm location under the guidance of standard-speed 10 fps Flat Panel Detector (FPD) fluoroscopy. Following this, a flow diverter stent was placed in the parent vessel covering the aneurysm neck and diverting the flow away from the aneurysm. HSA was performed before and after placement of the flow diverter using a 1000 fps CdTe photon-counting detector (Aries, Varex). The detector was mounted on a motorized changer and was used with a commercial x-ray c-arm system (Fig. 1). During these procedures Omnipaque iodinated contrast was injected into the aneurysm area using a computer-controlled injector at a steady rate of 50 ml/min or 70 ml/min depending on the rabbit to visualize blood flow detail. The contrast injection and x-ray image acquisition were synchronized manually. The x-ray image acquisition was for a duration of 1 second, from which 300 ms was used for velocity analysis during systole. Detailed differences in flow patterns in the region of interest (ROI) between pre and post flow-diverter deployment were visualized at the high frame rates. The Optical Flow (OF) method for velocity calculation was performed upon the acquired 1000 fps HSA image sequences to provide quantitative evaluation of flow.

Midterm follow-up after embolization of intracranial aneurysms proximal to the circle of Willis with the Silk Vista flow diverter: the I-MAMA registry

PurposeThe aim of this registry was to assess technical success, procedural safety and mid- to long-term follow-up results of the Silk Vista “Mama” (SVM) flow diverter (BALT, Montmorency, France) for the treatment of proximal intracranial aneurysms.MethodsBetween August 2020 and March 2022, data from nine Italian neurovascular centres were collected. Data included patients’ clinical presentation, aneurysms’ size, location and status, technical details, overall complications and mid- to long-term angiographic follow-up.ResultsForty-eight aneurysms in 48 patients were treated using the SVM. Most aneurysms were small (≤ 10 mm: no. 29, 60%) and unruptured (no. 31, 65%); 13 aneurysms were recurrent after coiling or clipping. 37/48 aneurysms involved the internal carotid artery (77%). Optimal opening and complete wall apposition of the device were achieved in 46 out of 48 cases (96%). Four intra- or periprocedural complications occurred (two thrombotic complications successfully resolved, one cerebellar ischemia, one perirenal hematoma), without new neurological deficit. No significant intra-stent stenosis or stent displacement was observed during follow-up. No FD-related morbidity nor mortality was reported. At midterm (6–12 months) to long-term (> 12 months) follow-up, complete aneurysm occlusion (OKM D) was achieved in 76% of cases. Eighty-eight percent of patients had complete aneurysm occlusion or entry remnant (OKM D + C).ConclusionsOur experience suggests that the new generation of low-profile SVM flow diverter for the treatment of proximal intracranial aneurysms is safe and effective, with low rates of intraprocedural complications and acceptable mid- to long-term occlusion rate.

Flow Diverter Combined with Coil Embolization for Acutely Ruptured Intracranial Aneurysms: A Single Center Experience

Background and PurposeExtensive research has confirmed the safety and effectiveness of flow diverters in the treatment of unruptured intracranial aneurysms. However, their use in cases of acute rupture remains a subject of debate. MethodsThis study was conducted as a single-center retrospective investigation from January 2018 to January 2022 and included patients with acutely ruptured intracranial aneurysms (within three days of rupture) who were treated using the Pipeline Embolization Device (PED) with adjunctive coil embolization. Patient demographics, operative procedures, and outcomes were analyzed. Antiplatelet therapy included intra-arterial tirofiban and postoperative dual therapy with clopidogrel and aspirin. ResultsA total of 21 patients (5 males, 16 females) diagnosed with acutely ruptured intracranial aneurysms were included in this study. The aneurysm types included 7 blood blister-like aneurysms (30.0%), 3 dissecting (14.3%), and 1 fusiform aneurysm (4.8%). Perioperative complications occurred in 2 patients (9.5%), and both cases involved thrombogenesis. Nineteen patients completed digital subtraction angiography during follow-up, with an average follow-up time of 8.7 months (5−18 months). Results showed a complete embolization rate of 94.7% (18/19), with a partial aneurysm still present in 1 patient. A total of 90.4% (19/21) of patients had a favorable prognosis (modified Rankin Scale score = 0−2). ConclusionThe PED with adjunctive coil embolization proved to be a viable option for managing acutely ruptured intracranial aneurysms, notwithstanding the potential for ischemic complications.

158 Preclinical Direct Endoluminal Assessment of Endothelialization After Flow Diversion With Microangioscopy

INTRODUCTION: Endoluminal imaging (ELI) is an emerging adjunct in endovascular cerebral aneurysm management. Indirect ELI, as with optical coherence tomography, may be useful in detecting malapposition after flow diversion (FD). Direct ELI technologies, such as with our previous described microangioscope, have been shown to be able to delineate between different thrombi and visualize neoepithelialization after stent placement with high resolution. METHODS: In a rabbit model we implanted each left common carotid artery (CCA) with a shielded FD (Medtronic Pipeline Vantage) and non-shielded FD (Medtronic Pipeline Flex) in the right CCA. We studied 9 animals in 3 groups: 1) no periprocedural antiplatelet therapy, 2) aspirin 81 mg daily, 3) aspirin 81 mg and clopidogrel 75 mg daily. FD thrombosis, stenosis, malapposition, and neoepithelialization were all evaluated by diagnostic cerebral angiography (DSA) and microangioscopy after 30 days. DSA and angioscopic video were analyzed by independent evaluators and compared with histopathologic analysis. RESULTS: In the aspirin and DAPT groups, there were no significant observed differences in stent thrombosis, stenosis, malapposition, or neoepithelialization between the shielded and non-shielded FDs in each rabbit as measured by histologic analysis. There was significantly more thrombus formation in Group 1. Neointimal thickness as measured by the microangioscope was highly correlated with histology (r = 0.72, p = 0.016). Inter-rater agreement of microangioscope videos was highest for FD thrombosis and stenosis. CONCLUSIONS: There were no significant differences between in-stent thrombosis, stenosis, malapposition, or neopithelialization between shielded and non-shielded FDs. Microangioscopy measurements for neointimal thickness were highly correlated with pathology, and thus may be a helpful adjunct to DSA in FD follow-up.

308 Improvement in Cranial Nerve Neuropathies Following Treatment of Intracranial Aneurysms With Flow Diverters: Institutional Outcomes and Meta-analysis of Literature

INTRODUCTION: Cranial nerve (CN) neuropathies are rare presenting symptoms of intracranial aneurysms. Ophthalmological outcomes for symptomatic aneurysms treated with flow diversion are not well established. METHODS: We conducted a retrospective review of our institutional database for patients with intracranial aneurysms presenting with CN neuropathies who underwent treatment with flow diversion between 2015 and 2023. Systematic review of the literature was performed using Medline, EMBASE, Cochrane, and manual citation searches. Random effects meta-analysis was used. RESULTS: Twelve out of 136 studies were included in this meta-analysis, totaling 261 patients. The results were combined with our institutional data. The pooled rate of improvement in any CN neuropathies following flow diversion was 76% (95% CI, 67%-84%, n = 272). Patients presenting with CNII deficits were less likely to improve following treatment compared to other CN neuropathies (pooled OR [pOR] 0.32, 95% CI, 0.16-0.63, n = 224). The pooled rate of clinical improvement was 53% in CNII deficits (95% CI, 42%-65%, n = 80) and 80% in other CN deficits (95% CI, 71%-88%, n = 106). Intervention within one month of presentation was associated with improvement (pOR 6.53, 95% CI, 1.34-31.81, n = 33). Adjunctive coiling did not demonstrate effect on the improvement rate (pOR 0.38, 95% CI, 0.07-2.13, n = 31). Near total occlusion (Raymond Roy Occlusion Classification of 1 or 2, or O'Kelly-Marotta scale of C or D) was associated with symptomatic improvement (pOR 5.29, 95% CI, 1.66-16.90, n = 118), but not total occlusion (pOR 2.83, 95% CI, 0.97-8.23, n = 118). CONCLUSIONS: Flow diversion improves CN outcomes in patients with symptomatic intracranial aneurysms. These results support the theory that CN neuropathies depend more on the pulsatility of the aneurysm sac rather than mass effect. The inferior rate of improvement in CNII deficits compared to other CN symptoms may imply an additional, more irreversible mechanism contributing to CNII visual deficits.

310 The Derivo 2 Heal Embolization Device in the Treatment of Ruptured and Unruptured Intracranial Aneurysms: A Retrospective Multicenter Analysis

INTRODUCTION: The Derivo 2 Flow diverter has been previously described for the treatment of intracranial aneurysms. To overcome the risk of in-stent thrombosis and thrombo-embolism as a well-known risk of intracranial flow diverter implantation, the device was modified by adding an antithrombogenic fibrin-heparin coating. The fibrin network aims at surface passivation, reduction of inflammatory reactions and building a scaffold for endothelial cells. The covalently bound heparin reduces the thrombogenicity by locally reducing platelet activation and inhibtion of the coagulation cascade. METHODS: We perform a retrospective multicenter, single-arm trial at seven neurovascular centers. Patients treated with the D2H for unruptured or ruptured intracranial aneurysms are included in the study. The primary endpoint is angiographic aneurysm occlusion at six months as assessed by the O’Kelly-Marotta (OKM) grading scale. Clinical outcome is evaluated after intervention and at six months with major morbidity defined as modified Rankin Scale scores (mRS) of 3-5. RESULTS: Between October 2021 and March 2023 56 patients with ruptured and unruptered intracranial aneurysms were treated with the D2H embolization device and included in our analysis. All patients were subjected to the regular antiplatelet pre- and post-treatment medication as per standard of care in the respective institutions with no deviations being reported. No differences in terms of technical device properties were observed. By the time of the conference, data evaluation will be completed and clinical as well as safety results including angiographic follow-up will be available. CONCLUSIONS: The Derivo 2 heal Flow Diverter is a promising antithrombogenic coated device for the treatment of ruptured and unruptured intracranial aneurysms. Early post-interventional and long-term results will provide further insight into the effect of antithrombogenicity and endothelial healing.

213 Acute Flow Diversion for Ruptured Cerebral Aneurysms Arising From Vessels of Small Caliber Using FRED Jr: A Clinical Case Series

INTRODUCTION: Ruptured aneurysms arising from small caliber (<2.5 mm) or distal vessels beyond the circle of Willis are considered challenging for all treatment modalities. Recently, the FRED Jr stent, designed for flow diversion in small arteries, was approved in the US for the treatment of non-ruptured aneurysms. METHODS: Clinical and radiological records of patients sustaining SAH treated with FRED Jr between June 2020 and October 2022 were reviewed. Treatment course including anti-platelet therapy, external ventricular drain (EVD) management, and vasospasm, as well as clinical outcomes were analyzed. Angiographic results were assessed according to the O’Kelly-Marotta (OKM) scale. RESULTS: Nine patients with at a median age of 62 (27-75) were included. The median Hunt Hess score was 2 (IQR 1) and modified Fischer score was 4 (IQR 1). Six aAneurysms’ morphologies included were saccular (6 case), 1 blister (1 case) and 2 were and dissecting (2 cases) type, located at the ACOM complex (3), A2/A3 (3), M2/M3 (1), V4 (1), and P2 (1) segments. All stents were deployed successfully with no intraprocedural complications. Post-operatively, no re-bleeding events were encountered. Vasospasm therapy was initiated in 6 cases, and no symptomatic EVD-related hematomas were observed. Post- operative ischemic events were encountered in 2 cases. Median 3-month mRS was 2 (IQR 1) for the7 surviving patients, and 3-months radiographic follow-up revealed OKM scale D in 4/7 cases. CONCLUSIONS: Flow diversion as a potential treatment strategy for acutely ruptured aneurysms arising from small caliber vessels is feasible using FRED Jr. Since As the complication profile reported in this series is comparable to historical microsurgical cohorts and effective protection was conferred by this treatment modality, our small cohort provides a glimpse into acute flow diversion for this subset of difficult-to-treat aneurysms.

Current research status and future of endovascular treatment for basilar artery aneurysms.

Aneurysms occurring along the basilar artery (BA) account for <1% of all intracranial aneurysms. Endovascular treatment (EVT) in particular is recommended for large unruptured BA aneurysms and ruptured BA aneurysms. Given that EVT techniques vary, a detailed review of EVT for BA aneurysms is necessary. In this review, the following issues were discussed: the anatomy and anomalies of the BA, the classification of BA aneurysms, the natural history of BA aneurysms, the status of open surgery, the use of EVT for various types of BA aneurysms and the deployment of new devices. According to the findings of this review and based on our experience in treating BA aneurysms, traditional coiling EVT is still the optimal therapy for most BA aneurysms. However, in some BA aneurysms, flow diverter (FD) deployment can be used. In addition, there are also some new devices, such as intrasaccular flow disruptors and stent-like devices that can be used to treat BA aneurysms. In general, EVT can yield good clinical and angiographic outcomes for patients with BA aneurysms. In addition, recent new devices and techniques, such as new-generation FDs generated via surface modification and virtual reality simulation techniques, show promise for EVT for BA aneurysms. These devices and techniques may further improve EVT outcomes for BA aneurysms.

693 Treatment Differences of Ruptured Versus Unruptured Wide Neck Aneurysms: Insights From the EVERRUN Registry

INTRODUCTION: Wide neck aneurysms (WNAs) are more challenging to treat compared to narrow neck aneurysms, requiring more advanced techniques. The Wide Neck / EVERRUN Registry compared endovascular versus microsurgical techniques for unruptured and ruptured aneurysms. METHODS: Saccular and not previously treated WNA were examined. WNA definition was aneurysm neck=4mm or dome-to-neck-ratio (DTNR)&lt;2. Differences in treatment strategy (EVT vs. MS) and angiographic results were the primary outcomes. Angiographic outcome was assessed immediately following treatment and at last follow-up using the Raymond-Roy scale (core lab review, adequate occlusion: RR 1-2). Statistical significance set at p&lt;0.05. All analysis performed using R(v.4.2.1). RESULTS: 310 WNA were included (87 ruptured (R) aneurysms vs. 223 unruptured (U)). There were no significant differences in the rate of EVT vs. MS between ruptured (R) vs. unruptured (U) aneurysms (Clipping, R: 36.8%, U: 37.7%). Amongst EVT, ruptured WNA were treated more with stand-alone coiling (R: 27.6%, U: 5.8%) and balloon-assisted coiling (R: 32.2%, U: 10.8%). Unruptured aneurysms were more commonly treated with flow diversion (R: 1.1%, U: 22.9%) and stent-assisted coiling (R: 2.3%, U: 21.5%) (p &lt; 0.05 for all). Ruptured aneurysms had higher rates of adequate angiographic occlusion after initial treatment (R: 88.5%, U: 74.3%) (p &lt; 0.05). There was no difference in final adequate occlusion at follow-up (R: 90.1%, U: 90.7%). Ruptured WNA had higher retreatment rates (R: 14.3%, U: 3.1%) (p &lt; 0.05). Ruptured WNA had more procedural complications (R: 28.7%, U: 17%) (p &lt; 0.05). Rates of good mRS (0-2) at one year were higher in unruptured WNA patients (R: 72.8%, U: 90.3%) (p &lt; 0.05). CONCLUSIONS: WNA rupture status significantly influences the EVT choice, likely based on the need for DAPT. The lower initial adequate occlusion in the unruptured cohort is likely due to more flow diverter use. Ruptured WNAs were more difficult to treat as evidenced by higher rates of retreatment and procedural complications, however this did not impact the final angiographic outcomes.

Flow diverters versus stent-assisted coiling in unruptured intracranial vertebral artery dissecting aneurysms.

Flow diverters (FDs) have been used in unruptured intracranial vertebral artery dissecting aneurysms (IVADAs) with seemingly more favorable outcomes compared with stent-assisted coiling (SAC). However, the benefits of FDs over SAC in unruptured IVADAs need further evaluation. This was a propensity score-matched, retrospective cohort study. Consecutive patients with unruptured IVADAs treated with FDs or SAC at the authors' hospital between January 2016 and December 2020 were reviewed. Propensity score matching at 1:1 was based on age, significant stenosis adjacent to aneurysmal dilatation, maximum diameter, and posterior inferior cerebellar artery involvement. Periprocedural cerebrovascular complications and angiographic and clinical outcomes were compared between the two matched groups. A total of 124 unruptured IVADAs in 123 patients (median age 53 [interquartile range 47-59] years; 101 men) were included. The FD and SAC groups included 65 and 59 IVADAs, respectively. Propensity score matching resulted in 47 matched pairs. The rates of immediate complete occlusion were significantly lower in the matched FD group than in the matched SAC group (6.4% vs 68.1%, p < 0.001). The rates of periprocedural cerebrovascular complications were comparable between the two matched groups (6.4% vs 6.4%, p > 0.99). At last follow-up, the rates of complete occlusion (89.4% vs 80.9%, p = 0.39) and favorable clinical outcomes (100.0% vs 97.9%, p > 0.99) were comparable, whereas the rate of recanalization was significantly lower in the matched FD group than in the matched SAC group (0.0% vs 12.8%, p = 0.03). Although the difference between the rates of in-stent stenosis was not statistically significant (17.0% vs 6.4%, p = 0.18), the difference in the effect measures was considerable. In unruptured IVADAs and compared with SAC, FDs provide comparable rates of periprocedural cerebrovascular complications, favorable clinical outcomes, and follow-up complete occlusion, lower rates of immediate complete occlusion and follow-up recanalization, and likely higher rates of in-stent stenosis.