Flow-diverting Stents Research Articles

Investigation of the effect of anticoagulant usage in the flow diverter stent treatment of the patient-specific cerebral aneurysm using the Lagrangian coherent structures

Anticoagulants are prescribed to the flow diverter treated patients to diminish the risk of embolism in the arteries. In the present study, digital subtraction angiography images of a 49-year-old female patient with a left paraophthalmic aneurysm were used to build a numerical model to investigate the effect of an anticoagulant on hemodynamics at the aneurysm site. The Carreau-Yasuda viscosity model was utilized to define blood viscosity, and the coefficients of the viscosity model were updated based on the usage of warfarin. The five-cardiac cycle-long numerical simulations were performed, and Lagrangian coherent structures, hyperbolic time, and fluid particle analyses were also employed in the numerical models. These analyses allowed us to evaluate the formation of stagnated regions, recirculation zones, and the number of jailed particles inside the aneurysm sac following a flow diverter placement. It is realized that anticoagulant use caused blood to be less viscous, yielding a substantial amount of incoming blood flow to enter the aneurysm sac. Only 12% of the nearly 25,000 fluid particles seeded from the artery inlet have stayed inside the sac. Furthermore, the deviation between warfarin added blood and normal blood flow becomes more extensive, with every heartbeat undermining the effectiveness of patient-specific CFD models when the use of anticoagulants is overlooked in the viscosity models.

Three-Dimensional Intraarterial Vaso Computed Tomography Depiction of Pipeline Flex with Shield Technology Flow Diverter Stent in Ruptured Blister Aneurysm of Supraclinoid Internal Carotid Artery

AbstractBlister aneurysms are intracranial arterial lesions originating at nonbranching sites of the dorsal supraclinoid internal carotid artery and basilar artery.1 Among different treatment options, the use of flow-diverting devices is gaining popularity and has the potential for becoming the standard of care.2 Radiological evaluation of flow diverter braid expansion and vessel wall apposition during procedure has become useful in preventing life-threatening complications. Incomplete coverage of an aneurysm neck, kinking, or incomplete expansion and malapposition of a stent carries a significant risk for thromboembolic events.3 4

Development of a Clamping Device for Tensile Testing of Intracranial Flow Diverter Stents

Abstract The main danger of a brain aneurysm (a sack-like bulge on the vessel wall) is that in the event of a rupture a severe hemorrhage can occur which may cause death. However, if doctors have tools at their disposal, such as numerical models and simulations for analyzing patient-specific blood vessels, they could use them to decide if a particular treatment is necessary and if so, when. For such models, the different mechanical characteristics of the flow control devices are the input data. Several of these mechanical properties of the devices, such as modulus of elasticity and tensile strength, are determined by tensile testing. In the course of our research, we have developed a clamping device suitable for uniaxial tensile testing of flow diverter stents.

Treatment of acute aneurysmal subarachnoid haemorrhage with primary flow diversion: 5-year single-centre experience

To evaluate the safety and efficacy of treatment of patients presenting with acute aneurysmal subarachnoid haemorrhage (SAH) with primary flow-diverting stents (FDS; with or without adjuncts), with comparison to the published literature. A retrospective single-centre review was undertaken of prospectively obtained data on patients treated for SAH over a 60-month period. Of 354 patients treated for SAH during that time period, 24 patients with a total of 25 aneurysms were identified. Baseline patient demographics were recorded and clinical and imaging outcomes assessed. Eighty-eight per cent (22/25) of the aneurysms were completely occluded (Raymond-Roy 1) at mean 12-month follow-up. The minor complication rate was 12.5% (3/24) without permanent morbidity. Mortality rate was 4% (1/25) after one patient died following aneurysmal rebleed on day 7 post-procedure. Forty-two per cent (10/24) of patients had a high-pressure shunt placed prior to endovascular treatment, no haemorrhagic complications of neurosurgical intervention were observed. The necessity of dual antiplatelet therapy (DAPT) therapy when deploying FDS will rightly continue to limit their use in the acutely ruptured setting to a case-by-case basis whereby other treatment options are deemed unsafe. Methods employed to minimise subsequent haemorrhagic risks from DAPT in these patients may be worthy of further investigation.

Prediction of Cerebral Aneurysm Hemodynamics With Porous-Medium Models of Flow-Diverting Stents via Deep Learning

The interventional treatment of cerebral aneurysm requires hemodynamics to provide proper guidance. Computational fluid dynamics (CFD) is gradually used in calculating cerebral aneurysm hemodynamics before and after flow-diverting (FD) stent placement. However, the complex operation (such as the construction and placement simulation of fully resolved or porous-medium FD stent) and high computational cost of CFD hinder its application. To solve these problems, we applied aneurysm hemodynamics point cloud data sets and a deep learning network with double input and sampling channels. The flexible point cloud format can represent the geometry and flow distribution of different aneurysms before and after FD stent (represented by porous medium layer) placement with high resolution. The proposed network can directly analyze the relationship between aneurysm geometry and internal hemodynamics, to further realize the flow field prediction and avoid the complex operation of CFD. Statistical analysis shows that the prediction results of hemodynamics by our deep learning method are consistent with the CFD method (error function <13%), but the calculation time is significantly reduced 1,800 times. This study develops a novel deep learning method that can accurately predict the hemodynamics of different cerebral aneurysms before and after FD stent placement with low computational cost and simple operation processes.

Flow-diverter stent to manage intracranial aneurysms: A single center experience.

Endovascular coil embolization is an important method for managing intracranial aneurysms. However, aneurysm coiling may fail or be insufficient in geographically difficult aneurysms. A flow-diverter stent (FDS) is an alternative in these difficult coiling aneurysms. Thus, this study reports the experience and outcome of FDS management of intracranial aneurysms. Over 29 months, FDS treated 125 patients with 163 intracranial unruptured aneurysms. This study enrolled 31 men and 94 women, ranging from 17 to 81 years (mean, 58 years). Clinical data, aneurysm characteristics, and angiographic and clinical outcomes of patients treated by FDS were retrospectively assessed. The current study found 151 (93%) aneurysms in the internal carotid artery. Most aneurysms (n = 118; 72%) were small (<7 mm). The mean aneurysm size was 6.2 mm (range, 2-38 mm). Follow-up angiography was available in 53 patients with 74 aneurysms (mean, 13 months). Successful FDS deployment in an ideal position was found in 125 of 130 patients (96%). Complete obliteration (CO) was achieved in 58 aneurysms (78%) in the mean 13-month angiographic follow-up. Smaller aneurysms (<7 mm) had a CO tendency than larger aneurysms (p < 0.01) in midterm follow-up. Seven patients (5.6%) had intraprocedural complications (in-stent thrombosis, three patients; distal embolic, two patients; iatrogenic carotid-cavernous fistula, and subarachnoid hemorrhage, one patient). Two patients (1.6%) suffered from permanent procedure-related morbidity (n = 1) or mortality (n = 1). No late hemorrhagic events or stent displacement occurred during the follow-up period. Despite few procedural complications and some pieces of evidence of insufficient aneurismal treatment in a midterm angiographic follow-up, FDS was effective and safe in managing intracranial unruptured aneurysms, particularly in smaller aneurysms, which had better CO than larger ones.

First Experience of Three Neurovascular Centers With the p64MW-HPC, a Low-Profile Flow Diverter Designed for Proximal Cerebral Vessels With Antithrombotic Coating.

Background: In the last decade, flow diversion (FD) has been established as hemodynamic treatment for cerebral aneurysms arising from proximal and distal cerebral arteries. However, two significant limitations remain—the need for 0.027” microcatheters required for delivery of most flow diverting stents (FDS), and long-term dual anti-platelet therapy (DAPT) in order to prevent FDS-associated thromboembolism, at the cost of increasing the risk for hemorrhage. This study reports the experience of three neurovascular centers with the p64MW-HPC, a FDS with anti-thrombotic coating that is implantable via a 0.021” microcatheter.Materials and methods: Three neurovascular centers contributed to this retrospective analysis of patients that had been treated with the p64MW-HPC between March 2020 and March 2021. Clinical data, aneurysm characteristics, and follow-up results, including procedural and post-procedural complications, were recorded. The hemodynamic effect was assessed using the O'Kelly–Marotta Scale (OKM).Results: Thirty-two patients (22 female, mean age 57.1 years) with 33 aneurysms (27 anterior circulation and six posterior circulation) were successfully treated with the p64MW-HPC. In 30/32 patients (93.75%), aneurysmal perfusion was significantly reduced immediately post implantation. Follow-up imaging was available for 23 aneurysms. Delayed aneurysm perfusion (OKM A3: 8.7%), reduction in aneurysm size (OKM B1-3: 26.1%), or sufficient separation from the parent vessel (OKM C1-3 and D1: 65.2%) was demonstrated at the last available follow-up after a mean of 5.9 months. In two cases, device thrombosis after early discontinuation of DAPT occurred. One delayed rupture caused a caroticocavernous fistula. The complications were treated sufficiently and all patients recovered without permanent significant morbidity.Conclusion: Treatment with the p64MW-HPC is safe and feasible and achieves good early aneurysm occlusion rates in the proximal intracranial circulation, which are comparable to those of well-established FDS. Sudden interruption of DAPT in the early post-interventional phase can cause in-stent thrombosis despite the HPC surface modification. Deliverability via the 0.021” microcatheter facilitates treatment in challenging vascular anatomies.

Multiphysics coupling numerical simulation of flow-diverting stents in the treatment of patients with pulsatile tinnitus.

Patients with pulsatile tinnitus (PT) have unstable treatment effects after resurfacing surgery. Flow-diverting stents (FDS) are proposed as a potential method for the treatment of PT, but the therapeutic effect is not clear. This study aimed to investigate the efficacy of FDS in the treatment of patients with PT induced by sigmoid sinus diverticulum (SSD) and sigmoid sinus wall dehiscence (SSWD). In addition, we aimed to explore the treatment mechanism of PT. Transient-state multiphysics coupling numerical simulation method based on computed tomography angiography of five patients was used to clarify the biomechanical and acoustic states before and after FDS placement. FDS was placed to prevent the blood flow from impacting the vessel wall in the SSD and SSWD areas. Low blood flow velocity (<0.0391 m/s), high relative residence time (>10Pa-1 ), and low wall shear stress of SSD might lead to thrombosis after FDS placement. The average pressure on the SSWD area of each patient decreased by 13.77%, 18.82%, 29.23%, 19.03%, and 11.20%. The average displacement of the vessel wall on the SSWD area showed acute pulsation and decreased by 15.29%, 14.64%, 30.22%, 41.03%, and 21.28%. The average sound pressure level at the tympanum decreased by 14.01%, 9.33%, 17.66%, 18.88%, and 25.18%, respectively. In brief, FDS was placed to avoid blood flow impacting vessels and reduce the vibration of vessels in the short term, thereby attenuating the degree of PT. The long-term prognosis was that the SSWD area was blocked after SSD thrombosis. Therefore, FDS might be an effective method for the treatment of PT induced by SSD and SSWD. This study would provide a theoretical basis for the treatment of PT and an exploration of FDS design in the treatment of PT.

Early institutional experience using the TracStar Large Distal Platform in endovascular flow diversion.

The delivery of flow-diverting stents (FDS) necessitates a degree of catheter support beyond that required for endovascular coiling. The TracStar Large Distal Platform (LDP) is a novel 0.088″ platform intended for navigation into the intracranial internal carotid artery (ICA). We present an early institutional experience using the TracStar LDP in 44 cases of endovascular aneurysm embolization using FDS. Inclusion criteria for this single-center retrospective review encompassed all patients >18 years of age who were treated for intracranial aneurysms. Procedural success was defined as successful stent deployment using the TracStar LDP. Other outcomes included periprocedural complications, use of an intermediate catheter, length of stay, and discharge disposition. The TracStar LDP was utilized in 44 consecutive FDS cases in 42 patients. Cavernous segment aneurysms constituted the majority of cases (12/42; 28.6%), followed by posterior communicating artery (8/42; 19.0%) and supraclinoid aneurysms (8/42; 19.0%). Successful FDS deployment was achieved in 43/44 cases. The LDP achieved stable positioning within the ascending cavernous ICA in 63.6% of cases. A biaxial system was utilized in 54.5% of cases. There was one complication potentially related to use of the TracStar LDP, which was an asymptomatic ICA vessel dissection managed conservatively. The TracStar LDP is safe and effective during use in the endovascular treatment of intracranial aneurysms with a FDS. Access to the ascending portion of the cavernous ICA was regularly achieved, and the platform allowed for both biaxial and triaxial configurations.

CFD Study on the Efficacy of Flow Diverter Stent Placement for Cerebral Aneurysms

The effect of flow diverter (FD) stent placement as a cerebral aneurysm treatment on hemodynamics was systematically investigated via numerical simulation. The aneurysm diameter was set to 8 mm and 12 mm, with an aspect ratio (AR) of 1.2 and 1.9, respectively. The curvature of the parent artery was also varied for the following three types: straight, inside, and outside. The blockage ratio of the FD stent was set to 31 %. The results reveal that, regardless of artery shape, the FD stent drastically modifies the flow in the aneurysm, including changing the flow direction in the systolic phase. In most cases, the flow rate into the aneurysm is significantly reduced by the stent; however, in the case of a straight artery, the flow rate is increased for the aneurysm model with AR = 1.9. The oscillatory shear index (OSI) generally increases owing to FD stent placement while the wall shear stress is substantially decreased. In particular, a high OSI area is widely distributed in the large aneurysm sac (AR = 1.9) for straight and internal artery cases. Although idealized aneurysm models are employed in the present study and further parametric studies are required, particularly with respect to stent configuration, these facts may explain the unexpected outcome in some (but not all) large aneurysm cases.

Virtual Reality Visualization of CFD Simulated Blood Flow in Cerebral Aneurysms Treated with Flow Diverter Stents

Virtual reality (VR) has the potential to be a powerful tool for the visualization of simulated blood flow in cerebral aneurysms. This paper presents our study aimed at developing the VR visualization of computational fluid dynamics (CFD) simulations of cerebral aneurysms treated with flow-diverting (FD) stents. First, a spherical sidewall aneurysm located at a simplified internal carotid artery was considered for investigating the impact of stent deployment and positioning on the corresponding spatially time-varying blood flow behavior. The three-dimensional unsteady blood flow over a cardiac cycle was simulated numerically using the finite volume method, and the distributions of hemodynamic parameters inside the aneurysm sac, and on its wall, were presented with and without stent cases. Two stent positions, with and without a gap between the artery wall and stent, were considered to show the influence of correct stent position on aneurysm treatment. Second, a straightforward workflow was developed to import, process, and visualize the CFD analysis data in a VR environment by using open-source software with a high resolution. The Unity3D engine was used for displaying the processed animations in a VR environment operated on a head-mounted display (HMD). The refining process of each frame of time-varying CFD data was automated. The animated flow elements rendered in the VR environment were velocity vectors, velocity contours, streamlines, particle traces, and point clouds. CFD results showed that proper stenting facilitates thrombosis and occlusion of the aneurysm by modification of the flow patterns, which leads to lower inflow jet velocities into the aneurysm, longer turnover time, lower aneurysm-averaged kinetic energy, and lower wall shear stress. Additionally, the results indicated that a gap between the stent and the parent artery may lead to undesirable hemodynamic alterations. The VR visualization illustrated that the recognition of the potential in danger regions of aneurysms and the evaluation of the performance of FD stents in aneurysm treatment can be conducted without the need for several slices through the parent artery and aneurysm, as is required for traditional postprocessing methods. Through VR visualization, the details of the simulation results become readily available by navigating in the 3D animated flow elements using a high-degree-of-freedom headset.

REtrospective Multicenter INdian Study of Derivo Embolization Device (REMIND): Periprocedural Safety.

PurposeThe treatment of aneurysms with characteristics such as complex morphology, fusiform, blister-like, wide neck, or large size has been revolutionized with the introduction of flow diverters. Though flow diverters have several advantages over coiling, they also have certain important disadvantages such as the lack of immediate protection against rupture, the risk of ischemic stroke, the need for antiplatelet therapy, and long latency for complete effect. The Derivo Embolization Device (DED) is a second-generation self-expanding device that is claimed to be less thrombogenic than conventional devices. We retrospectively evaluated the periprocedural safety and risks associated with the DED across 5 centers in India.Materials and MethodsThis is a multicentric, retrospective, observational study of DED, conducted at 5 high volume endovascular therapy centers in India from May 2018 to June 2020. Periprocedural demographic, clinical, and angiographic data were collected from a retrospective review of patient charts.ResultsA total of 96 patients, including 56 (58.3%) females, aged between 16–80 years (60±12.7 years) harboring 106 aneurysms were studied. Seven (7.3%) were noted to harbor multiple aneurysms: 6 had 3 aneurysms each, while 1 patient had 5 aneurysms. The following aneurysm characteristics were noted: average size, 9.8±8.2 mm; average neck size, 6.9±8.5 mm; wide-necked (>4 mm), 63 (59.4%); giant (>25 mm), 8 (7.5%); and anterior circulation location, 98 (92.5%). Eighteen (17%) of these were ruptured. Additional balloon angioplasty was performed in 5 (5.2%) patients. Intraprocedural problems were encountered in 3 (3.1%), of which only 1 had clinical implications, the device fish-mouthing with stent thrombosis resulting in a malignant middle cerebral artery territory infarction. The modified Rankin scale at 3 months was worse in 1 patient.ConclusionDED is a newer generation flow diverter stent with a low periprocedural complication rate.

Analyzing the Safety and Efficacy of Flow-Diverting Stents in Pediatric Aneurysms: A Systematic Review.

Ruptured intracranial aneurysms cause 50% of spontaneous subarachnoid hemorrhages in children, resulting in up to 65% mortality when left untreated. Although flow-diverting stents are especially suited to treat the fusiform and giant aneurysms more commonly found in children, the US Food and Drug Administration (FDA) has only approved their use in patients ≥22 years of age. Our objective was to assess the safety of flow-diverting stents in the treatment of pediatric patients with aneurysms through a systematic literature review using the PRISMA criteria. We used PubMed, Embase, and Web of Science to identify all published cases of pediatric aneurysms treated or retreated using flow-diverting stents from 2007 through 2019. Two independent researchers developed a consensus regarding the inclusion of all articles. Patient data were extracted from the identified articles and used to calculate the incidence rate of complications. From 1396 journal articles identified, 24 articles contained data on 37 pediatric patients that met the inclusion criteria. Of these 37 patients, 8 (21.6%) had a complication by last follow-up (death: 2; residual aneurysm: 2; parent artery occlusion: 4). This resulted in an incidence rate of 0.018 complications per patient at-risk month (95% CI 0.008-0.035). These data suggest that the use of flow-diverting stents for treatment of aneurysms in children may be safe and that FDA approval for this use should be evaluated. Although this analysis is comprised of case reports and case series, it represents the best attempt thus far to quantify the risk of using flow-diverting stents in children.

Magnetic particle imaging for artifact-free imaging of intracranial flow diverter stents: A phantom study.

Magnetic Particle Imaging (MPI) is a new, background- and radiation-free tomographic imaging method that enables near real-time imaging of superparamagnetic iron-oxide nanoparticles (SPIONs) with high temporal and spatial resolution. This phantom study aims to investigate the potential of MPI for visualization of the stent lumen in intracranial flow diverters (FD). Nitinol FD of different dimensions (outer diameter: 3.5mm, 4.0mm, 5.5mm; total length: 22-40mm) were scanned in vascular phantoms in a custom-built MPI scanner (in-plane resolution: ~ 2mm, field of view: 65mm length, 29mm diameter). Phantoms were filled with diluted (1:50) SPION tracer agent Ferucarbotran (10µmol (Fe)/ml; NaCL). Each phantom was measured in 32 different projections (overall acquisition time per image: 3200ms, 5averages). After image reconstruction from raw data, two radiologists assessed image quality using a 5-point Likert scale. The signal intensity profile was measured using a semi-automatic evaluation tool. MPI visualized the lumen of all FD without relevant differences between the stented vessel phantom and the reference phantom. At 3.5mm image quality was slightly inferior to the larger diameters. The FD themselves neither generated an MPI signal nor did they lead to relevant imaging artifacts. Ratings of both radiologists showed no significant difference, interrater reliability was good (ICC 0.84). A quantitative evaluation of the signal intensity profile did not reveal any significant differences (p>0.05) either. MPI visualizes the lumen of nitinol FD stents in vessel phantoms without relevant stent-induced artifacts.

Flow Redirection Endoluminal Device (FRED) with or without Adjunctive Coiling in Treatment of Very Large and Giant Cerebral Aneurysms.

Flow diverter stents are gaining wider use in the treatment of complex intracranial aneurysms; however, there are limited data on occlusion and complication rates of flow diverters in very large and giant aneurysms. This study assessed the safety and efficacy of flow redirection endoluminal device (FRED) and FRED Jr. stents in aneurysms ≥ 20 mm. We retrospectively analyzed all aneurysms ≥ 20 mm treated with FRED/FRED Jr. between January 2010 and June 2020 from three centers. Endpoints for clinical safety were absence of major stroke, aneurysmal rupture, or death and complete or near-complete occlusion for efficacy. Atotal of 45patients with very large (28cases) and giant aneurysms (17cases) were treated with FRED (41cases), and FRED Jr. (4cases) stents. The majority of the aneurysms (40/45, 88.9%) were in the anterior circulation. Adjunctive aneurysm coiling was performed in 21aneurysms (46.7%). Technical complications were encountered in 4procedures (8.9%). Ischemic and hemorrhagic complication rates were 6.7% and 8.9%, respectively. There was no case with major stroke. The mortality rate was 8.9%, and all cases were due to hemorrhagic complications from aneurysmal rupture. Median angiographic follow-up was 21.5months (range 3-60months). Complete occlusion was achieved in 32aneurysms (71.1%), and near-complete occlusion in 5cases (11.1%). The use of FRED/FRED Jr. for the treatment of aneurysms ≥ 20 mm achieved along-term aneurysm occlusion rate and asafety profile comparable to the large series reported with other flow diverter stents.

Endovascular Treatment of Posterior Circulation Saccular Aneurysms With the p64 Flow Modulation Device: Mid-and Long-Term Results in 54 Aneurysms From a Single Center

Objective: Flow diverter (FD) stents have become one of the most common tools for treating intracranial aneurysms; however, their role in treating posterior circulation aneurysms is still discussed with controversy. In this study, we evaluated the safety and effectiveness of p64 FD for the treatment of saccular, unruptured aneurysms in the posterior circulation over a long-term follow-up period in a single center.Methods: From our prospectively maintained database, we retrospectively identified patients who underwent treatment of an intracranial saccular aneurysm arising from the posterior circulation with ≥1 p64 FD implanted or attempted between October 2012 and December 2019. Aneurysms could have been treated with prior or concomitant saccular treatment (e.g., coiling, intra-aneurysmal flow diversion). Aneurysms with parent vessel implants other than p64, fusiform aneurysms, and dissections were excluded. Peri- and postprocedural complications, clinical outcome, and clinical and angiographic follow-up results were evaluated.Results: In total, 54 patients (45 female, 9 male; mean age 55.1 years) with 54 intracranial aneurysms met the inclusion criteria. In 51 cases (94.4%), one p64 was implanted; in 2 cases (3.7 %), two p64s were implanted; in one case, deployment of the p64 was not feasible. Procedural complications occurred in 3.7% and postprocedural complications in 9.3 %, respectively. Hemorrhagic complications occurred in 2/54 patients (3.7%), thereof one fatal parenchymal hemorrhage. Ischemic complications were observed in 5/54 patients (9.3%). Early, mid-term, and long-term angiographic follow-up examinations showed complete or near-complete aneurysm occlusion, defined according to the O'Kelly –Marotta (OKM) scale as OKM C + D in 56, 75.6, and 82.9 %, respectively. Asymptomatic side vessel occlusions occurred in 3.8%, each during the first follow-up.Conclusions: The implantation of a p64 FD is a safe and effective device for endovascular treatment of posterior circulation saccular aneurysms with a high success rate and low morbi-mortality.

Thin‐Film Patient‐Specific Flow Diverter Stents for the Treatment of Intracranial Aneurysms

AbstractIntracranial aneurysm treatment based on blood flow reduction with braided flow diverters (FDs) has become highly relevant. However, FDs have several limitations, e.g., sudden torsional collapse, variable porosity, and possible side branch occlusions. Thin‐film FD stents can overcome these limitations by offering high design freedom to produce patient‐specific implants. Here a workflow to design, fabricate, and characterize novel thin‐film FDs that can be individualized to meet patient‐specific needs is demonstrated. FD design is virtually optimized to achieve the best flow reduction and the lowest crimping resistance. Then, the optimal design is fabricated using state‐of‐the‐art thin‐film technology. The thin‐film FD is characterized for mechanical and flow behavior and is compared to a braided FD (Derivo; FD0). The thin‐film FD and FD0 show similar radial forces in the diameter range 2.6–4.5 mm, and the former exhibits no sudden torsional collapse. The flow analysis using MRI reveals that both FDs reduce the flow into the aneurysm. However, only the thin‐film FD maintains adequate flow into all the side branches. A thin‐film FD that overcomes braided FDs limitations while offering similar performance has been developed. The proposed framework is a pilot study for fabricating on‐demand patient‐specific thin‐film FD stents.

Comparison of Blister Aneurysm Treatment Techniques: A Systematic Review and Meta-Analysis

Blood blister aneurysms are small, thin-walled, rapidly growing side-wall aneurysms that have proved particularly difficult to treat, and evidence-based guidance for treatment strategies is lacking. A systematic review and meta-analysis was performed to aggregate the available data and compare the 3 primary treatment modalities. We performed a comprehensive literature search according to PRISMA guidelines followed by an indirect meta-analysis that compares the safety and efficacy of surgical, flow-diverting stents (FDS), and other endovascular approaches for the treatment of ruptured blood blister aneurysms. A total of 102 studies were included for quantitative synthesis, with sample sizes of 687 treated surgically, 704 treated endovascularly without FDS, and 125 treated via flow diversion. Comparatively, FDS achieved significantly reduced rates of perioperative retreatment compared with both surgical (P= 0.025) and non-FDS endovascular (P < 0.001). The FDS subgroup also achieved a significantly lower incidence of perioperative rebleed (P<0.001), perioperative hydrocephalus (P= 0.012), postoperative infarction (P= 0.002), postoperative hydrocephalus (P < 0.001), and postoperative vasospasm (P= 0.002) compared with those patients in the open surgical subgroup. Although no significant differences were found among groups on the basis of functional outcomes, angiographic outcomes detailed by rates of radiographic complete occlusion were highest for surgical (90.7%, 262/289) and FDS (89.1%, 98/110) subgroups versus the non-FDS endovascular subgroup (82.7%, 268/324). Flow diversion seems to be an effective treatment strategy for ruptured blood blister aneurysms, with lower rates of perioperative complications compared with surgical and other endovascular techniques, but studies investigating long-term outcomes after flow diversion warrant further study.

Flow Diversion for Reconstruction of Intradural Vertebral Artery Dissecting Aneurysms Causing Subarachnoid Hemorrhage-A Retrospective Study From Four Neurovascular Centers.

Objective: Dissecting aneurysms (DAs) of the vertebrobasilar territory manifesting with subarachnoid hemorrhage (SAH) are associated with significant morbi-mortality, especially in the case of re-hemorrhage. Sufficient reconstruction of the affected vessel is paramount, in particular, if a dominant vertebral artery (VA) is impacted. Reconstructive options include stent-assisted coiling and flow diversion (FD). The latter is technically less challenging and does not require catheterization of the fragile aneurysm. Our study aims to report a multicentric experience with FD for reconstruction of DA in acute SAH.Materials and Methods: This retrospective study investigated 31 patients (age: 30–78 years, mean 55.5 years) who had suffered from SAH due to a DA of the dominant VA. The patients were treated between 2010 and 2020 in one of the following German neurovascular centers: University Hospital Leipzig, Katharinenhospital Stuttgart, BG Hospital Bergmannstrost Halle/Saale, and Heinrich-Braun-Klinikum Zwickau. Clinical history, imaging, implanted devices, and outcomes were reviewed for the study.Results: Reconstruction with flow-diverting stents was performed in all cases. The p64 was implanted in 14 patients; one of them required an additional balloon-expandable stent to reconstruct severe stenosis in the target segment. One case demanded additional liquid embolization after procedural rupture, and in one case, p64 was combined with a PED. Further 13 patients were treated exclusively with the PED. The p48MW-HPC was used in two patients, one in combination with two additional Silk Vista Baby (SVB). Moreover, one patient was treated with a single SVB, one with a SILK+. Six patients died [Glasgow Outcome Scale (GOS) 1]. Causes of death were periprocedural re-hemorrhage, thrombotic occlusion of the main pulmonary artery, and delayed parenchymal hemorrhage. The remaining three patients died in the acute–subacute phase related to the severity of the initial hemorrhage and associated comorbidities. One patient became apallic (GOS 2), whereas two patients had severe disability (GOS 3) and four had moderate disability (GOS 4). Eighteen patients showed a complete recovery (GOS 5).Conclusion: Reconstruction of VA-DA in acute SAH with flow-diverting stents is a promising approach. However, the severity of the condition is reflected by high overall morbi-mortality, even despite technically successful endovascular treatment.

Intracranial stents in the management of wide-neck intracranial aneurysms

Intracranial aneurysms are bulges in vessels that are prone to rupture with attendant morbidity and mortality. Early detection and treatment can avoid rupture and its associated consequences. Endovascular treatment of aneurysms with wide neck can be challenging due to potential coil migration or protrusion. The use of intracranial stents and balloons can help overcome some of these management challenges. We present 3 cases of endovascular treatment of wide-neck intracranial aneurysms. The first patient presented with a wide-neck left middle cerebral artery aneurysm that was successfully treated with stent-assisted coiling with complete obliteration of the aneurysmal sac. The second patient presented with a large, cavernous internal carotid artery aneurysm that was successfully treated with a flow diverter stent with complete obliteration of the aneurysm while the third case presented with a wide-neck left posterior communicating artery aneurysm and was also successfully treated with stent-assisted coiling. Even though endovascular treatment of wide-neck intracranial aneurysms is technically challenging, the evolution of new treatment techniques such as the use of stents and stent-assisted coiling make these treatments safe.