Flow Diverter Treatment Research Articles

Finnish flow diverter study: 8 years of experience in the treatment of acutely ruptured intracranial aneurysms

BackgroundFlow diversion of acutely ruptured intracranial aneurysms (IAs) is controversial due to high treatment-related complication rates and a lack of supporting evidence. We present clinical and radiological results of the...

Ticagrelor versus Clopidogrel in the Dual Antiplatelet Regimen for Intracranial Stenting or Flow-Diverter Treatment for Unruptured Cerebral Aneurysms: A Single-Center Cohort Study.

Ticagrelor is a novel P2Y12 antagonist, and little is known about its efficacy and safety in the endovascular treatment of aneurysms. This study evaluated the efficacy and safety of ticagrelor versus clopidogrel for stent-assisted coiling or flow-diversion treatment in patients with unruptured cerebral aneurysms. From November 2003 to February 2019, two hundred one patients (mean age, 57.5 years; 156 women) with 233 unruptured aneurysms underwent stent-assisted coiling or flow-diversion treatment. All patients received antiplatelet therapy of aspirin plus clopidogrel (clopidogrel group, 121 patients with 140 aneurysms) or aspirin plus ticagrelor (ticagrelor group, 80 patients with 93 aneurysms). The clinical and radiologic data in each group were retrospectively reviewed and compared. Two hundred thirty-six procedures were performed, including stent-assisted coiling (n = 101) and flow diversion (n = 135). At 90 days, the primary outcome-a composite of any stroke and death-occurred in 9.9% of the clopidogrel group and 8.6% of the ticagrelor group (P = .822). Ischemic stroke occurred in 10 (7.0%) of the clopidogrel group and 7 (7.5%) of the ticagrelor group (P > .999). Disabling stroke occurred in 4 (2.8%) in the clopidogrel group and in 4 (4.3%) in the ticagrelor group (P = .716). Ninety-day death occurred in 3 (2.1%) in the clopidogrel group and 1 (1.1%) in the ticagrelor group (P > .999). Any bleeding at 90 days occurred in 13 (9.2%) in the clopidogrel group and 6 (6.5%) in the ticagrelor group (P = .479). Ticagrelor appears to be as effective and safe as clopidogrel in stent-assisted coiling or flow-diversion treatment for unruptured cerebral aneurysms.

Endoluminal flow diverters in the treatment of sidewall and bifurcation aneurysm: A systematic review and meta-analysis of complications and angiographic outcomes.

The use of endoluminal flow diversion in bifurcation aneurysms has been questioned due to the potential for complications and lower occlusion rates. In this study we assessed outcomes of endovascular treatment of intracranial sidewall and bifurcation aneurysms with flow diverters. In July 2020, a literature search for all studies utilizing endoluminal flow diverter treatment for sidewall or bifurcation aneurysms was performed. Data were collected from studies that met our inclusion/exclusion criteria by two independent reviewers and confirmed by a third reviewer. Using random-effects meta-analysis the target outcomes including overall complications (hematoma, ischemic events, minor ischemic stroke, aneurysm rupture, side vessel occlusion, stenosis, thrombosis, transient ischemic stroke, and other complications), perioperative complications, and follow-up (long-term) aneurysm occlusion were intestigated. Overall, we included 35 studies with 1084 patients with 1208 aneurysms. Of these aneurysms, 654 (54.14%) and 554 (45.86%) were classified as sidewall and bifurcation aneurysm, respectively, based on aneurysm location. Sidewall aneurysms had a similar total complication rate (R) of 27.12% (95% CI, 16.56%-41.09%), compared with bifurcation aneurysms (R, 20.40%, 95% CI, 13.24%-30.08%) (p = 0.3527). Follow-up angiographic outcome showed comparable complete occlusion rates for sidewall aneurysms (R 69.49%; 95%CI, 62.41%-75.75%) and bifurcation aneurysms (R 73.99%; 95% CI, 65.05%-81.31%; p = 0.4328). This meta-analysis of sidewall and bifurcation aneurysms treated with endoluminal flow diverters demonstrated no significant differences in complications or occlusion rates. These data provide new information that can be used as a benchmark for comparison with emerging devices for the treatment of bifurcation aneurysms.

Incomplete stent expansion in flow-diversion treatment affects aneurysmal haemodynamics: a quantitative comparison of treatments affected by different severities of malapposition occurring in different segments of the parent artery.

Incomplete stent expansion (IncSE) is occasionally seen in flow-diversion (FD) treatment of intracranial aneurysms; however, its haemodynamic consequences remain inconclusive. Through a parametric study, we quantify the aneurysmal haemodynamics subject to different severities of IncSE occurring in different portions of the stent. Two patient cases with IncSE confirmed in vivo were studied. To investigate a wider variety of IncSE scenarios, we modelled IncSE at two severity levels respectively located in the proximal, central, or distal segment of a stent, yielding a total of 14 treatment scenarios (including the ideal deployment). We examined stent wire configurations in 14 scenarios and resolved aneurysm haemodynamics through computational fluid dynamics (CFD). A considerable degradation of aneurysm flow-reduction performance was observed when central or distal IncSE occurred, with the maximal elevations of the inflow rate (IR) and energy loss (EL) being 10% and 15%. The underlying mechanism might be the increased resistance for flow to remain within the FD stent, which forces more blood to leak into the aneurysm sac. Counter-intuitively, a slight reduction of aneurysm inflow was associated with proximal IncSE, with the maximal further reduction of the IR and EL being 5% and 8%. This may be due to the disruption of the predominant parent-artery flow by the collapsed wires, which decreased the strength and altered the direction of aneurysmal inflow. The effects of IncSE vary greatly with the location of occurrence, revealing the importance of performing individualised, patient-specific risk assessment before treatment.

L-Arginine reduces downstream vascular contractility after flow-diverting device deployment: A preliminary study in a rabbit model.

Flow diverters (FDs) are an effective treatment for intracranial aneurysms, though not free from hemorrhagic complications. A previous study demonstrated increased vascular contractility after FD-implantation as a potential mechanism of distal complications. Our study aimed to investigate whether L-arginine medication affects vascular contractility following FD deployment in a rabbit model. FDs were implanted in the aorta of normal rabbits (+FD, n = 10), with sham-operated aorta as controls (n = 5). L-Arginine was given in the drinking water (2.25% L-arginine hydrochloride) of half of the +FD animals (+FD/+Arg). Force contraction vascular contractility studies were performed on the aortic rings proximal and distal to the FD using an organ bath. Total eNOS, eNOS(pS1177), eNOS(pT495), COX-2, and S100A4 were quantified by western analysis on total protein lysates from aortic segments, normalizing to GAPDH. Mean vascular contractility was 53% higher in distal relative to proximal aortic segments (P = 0.0038) in +FD animals, but were not significantly different in +FD/+Arg animals, or in sham-operated controls. The +FD animals expressed significantly reduced levels of eNOS(pS1177) than sham-operated controls (P = 0.0335), while both the +FD and +FD/+Arg groups had reduced levels of eNOS(pT495) relative to sham-operated controls (P = 0.0331 and P = 0.0311, respectively). These results suggest that L-arginine medication reduces distal vascular contractility after FD treatment via nitric oxide production and thus might mitigate risk for downstream complications.

Retrospective analysis of intracranial aneurysms after flow diverter treatment including color-coded imaging (syngo iFlow) as a predictor of aneurysm occlusion.

Flow Diverters (FD) have immensely extended the treatment of cerebral aneurysms in the past years. Complete aneurysm occlusion is a process that often takes a certain amount of time and is usually difficult to predict. Our aim was to investigate different syngo iFlow parameters in order to predict aneurysm occlusion. Between 2014 and 2018 patients with unruptured cerebral aneurysms treated with a FD were reviewed. Aneurysm occlusion and complication rates have been assessed.In addition, various quantitative criteria were assessed using syngo iFlow before, after the intervention, and after short and long-term digital subtraction angiography (DSA). A total of 66 patients hosting 66 cerebral aneurysms were included in this study. 87.9% (n = 58) aneurysms in the anterior and 12.1% (n = 8) in the posterior circulation were treated. Adequate aneurysm occlusion at long-term follow-up (19.05 ± 15.1 months) was achieved in 90.9% (n = 60). Adequately occluded aneurysm revealed a significantly greater peak intensity delay (PI-D, p = 0.008) and intensity decrease ratio (ID-R, p < 0.001) compared to insufficiently occluded aneurysms. Increased intra-aneurysmal contrast agent intensity (>100%) after FD implantation resulted in an ID-R < 1, which was associated with aneurysm growth during follow-up DSA. Retreatment with another FD due to foreshortening and/or aneurysm growth was performed in 10.6% (n = 7). Overall morbidity and mortality rates were 1.5% (n = 1) and 0%. The applied syngo iFlow parameters were found to be useful in predicting adequate aneurysm occlusion and foresee aneurysm growth, which might indicate the implantation of another FD.

Endovascular treatment of an unruptured ophthalmic artery aneurysm with a flow diverter: a case report

An unruptured aneurysm is often asymptomatic or present without neurological deficits, causing severe morbidity. However, the potential of this defect to rupture requires proper management. Herein, we report a case of an unruptured saccular aneurysm of the ophthalmic artery with initial clinical seizures. The patient was treated by flow diversion which redirects the blood flow that normally leads to the protrusion of the aneurysm back to the main vessel. Flow diversion is chosen because it is less risky and has a faster recovery time than other treatment options, but it is more expensive than others. Although this technology is not new, there is no report on its implementation in Indonesia. The patient was prescribed antiplatelet treatment for at least 6 months post-treatment, then she showed no sign of seizure or new focal neurological deficits 4 months post-treatment. The patients were expected to undergo digital subtraction angiography evaluation 6 months after flow diversion treatment, but it has not been performed due to the coronavirus disease 2019 pandemic.

The formation mechanism of acute dissection of blood blister-like aneurysm and its implication of endovascular treatment

BackgroundAcute mural dissection of the anterior wall of the internal carotid artery which may contribute to the development of blood blister-like aneurysms (BBLAs) was postulated, and stenting or flow diversion treatment across the soi-disant aneurysm was reported in this study.MethodsFrom December 2016 to December 2018, 8 patients presenting with subarachnoid hemorrhage (SAH) due to BBLA were subjected to endovascular treatment with stent-assisted coiling. Clinical outcomes were evaluated using a clinical outcome score scale.ResultsBased on angiograms, pathologic change involving the supraclinoid segments of the internal carotid artery (ICA) adjacent to BBLA was found in all patients. This pathologic change meant a focal dissection of the supraclinoid segment of the ICA which constituted the pathogenesis of BBLAs. Closed-cell, open-cell, and braided stents were used in 1, 1, and 6 patients, respectively. Complete obliteration was achieved following endovascular treatment among all 8 patients harboring BBLA. One re-bleeding successive to a closed-cell stent across the aneurysmal neck was observed. Follow-up angiograms revealed stable complete exclusion of all BBLAs from the parent vessel at 3 to 8 months. All patients had a favorable clinical outcome score of 0–1.ConclusionsAcute dissection of a focal point of the intracranial vessels underlies the development of BBLAs. Open-cell and braided-cell stent-assisted coiling may constitute appropriate treatment due to good apposition against the vascular walls. Adjunctive coils may facilitate immediate complete occlusion of BBLAs.

Remodeling of the Posterior Cerebral Artery P1-Segment after Pipeline Flow Diverter Treatment of Posterior Communicating Artery Aneurysms.

Introduction: Flow diverters such as the pipeline embolization device (PED) cause hemodynamic changes of the treated vessel segment. In posterior communicating artery (PcomA), aneurysms’ unique anatomic consideration have to be taken in account due to the connection between the anterior and posterior circulation. We hypothesize that in conjunction with PcomA remodeling, there will also be remodeling of the ipsilateral P1 segment of the posterior cerebral artery (PCA) after PED treatment for PcomA aneurysms. Methods: We retrospectively collected radiological as well as clinical data of PcomA aneurysm patients treated with PED including PcomA and P1 vessel diameters before and after treatment as well as patient and aneurysm characteristics. Results: Overall, 14 PcomA aneurysm patients were included for analysis and PED treatment was performed without complications in all patients. In 10 out of 14 patients (71%), a decrease in PcomA diameter was observed and there was a significant mean decrease of 0.78 mm in PcomA diameter on angiographic last follow-up (LFU) (p = 0.003). In the same patient population (10 out of 14 patients), there was meanwhile a significant mean increase of 0.43 mm in the ipsilateral P1 segment diameter observed (p = 0.015). These vessel remodeling effects were in direct correlation with aneurysm occlusion since all of these patients showed aneurysm occlusion at LFU while 29% showed only partial occlusion without vessel remodeling effects. A decrease in PcomA diameter was directly associated with aneurysm occlusion (p = 0.042). There were no neurologic complications on LFU. Conclusion: In the treatment of PcomA aneurysms with PED, the P1 segment of the PCA increases in diameter while the PcomA diameter decreases. Our results suggest that this remodeling effect is associated with aneurysm occlusion and decrease of PcomA is hemodynamically compensated for by an increase in the ipsilateral P1 diameter.

Timing and Spectrum of Neurological Complications After Flow Diverter Implantation for Intracranial Aneurysms.

Background and Purpose: The aim of this study was to characterize neurological complications after flow diverter (FD) treatment on a long follow-up cohort and identify predictive factors associated with these complications.Methods: This study was conducted on a monocentric cohort of patients treated for intracranial aneurysms by FD.Results: Between September 2008 and July 2018, 413 patients were treated for 514 aneurysms: 18% of the patients presented with at least one neurological complication during a median follow-up of 446 days (IQR 186–1,210). Sixty-one patients presented with ischemic complications, 13 with hemorrhagic ones and 10 with compressive processes. Among 89 neurological complications 64.5% were peri-operative (occurring within the 30 days following the procedure) and 35.5% were delayed after 1 month.Conclusions: Overall, neurological complications after FD implantation were overrepresented by cerebrovascular ischemic events occurring during the peri-operative period, but also in a delayed manner after 1 year. Long-term follow-up is relevant after aneurysm intervention using FD.

Flow-Diversion Treatment for Unruptured ICA Bifurcation Aneurysms with Unfavorable Morphology for Coiling.

Few reports described flow diversion for ICA bifurcation aneurysms. Our aim was to provide further insight into flow diversion for ICA bifurcation aneurysms difficult to treat with other strategies. Consecutive patients receiving flow diverters for unruptured ICA bifurcation aneurysms were collected. Aneurysm occlusion (O'Kelly-Marotta grading scale) and clinical outcomes were evaluated. Twenty saccular ICA bifurcation aneurysms were treated with the Pipeline Embolization Device deployed from the M1 to the ICA, covering the aneurysm and the A1 segment. All patients presented with an angiographic visualized contralateral flow from the anterior communicating artery. Mean aneurysm size was 6.5 (SD, 3.2) mm (range, 4.5-20 mm). All lesions had an unfavorable dome-to-neck ratio (mean/median, 1.6/1.6; range, 0.8-2.8; interquartile range = 0.5) or aspect ratio for coiling (mean/median = 1.5/1.55; range, 0.8-2.5; interquartile range = 0.6). One was a very large aneurysm (20 mm). Nineteen medium-sized lesions were completely occluded during the angiographic follow-up (13 months). No cases of aneurysm rupture or retreatment were reported. No adverse events were described. Aneurysm occlusion was associated with the asymptomatic flow modification of the covered A1 that was occluded and contralaterally filled among 10 patients (50%), narrowed among 9 patients (45%), and unchanged in 1 subject (5%). There was no difference in the mean initial diameter of the occluded (2.1 [SD 0.4] mm; range, 1.6-3 mm) and narrowed (2 [SD, 0.2] mm; range, 1.7-2.6 mm) A1 segments. Medium-sized unruptured ICA bifurcation aneurysms with unfavorable morphology for coiling can be treated with M1 ICA flow diversion. Aneurysm occlusion is associated with flow modifications of the covered A1 that seems safe in the presence of a favorable collateral anatomy through the anterior communicating artery complex.

Treatment of intracranial aneurysms using the new Surpass Evolve flow diverter: Safety outcomes and six-month imaging follow-up

Background and purposeSeveral studies have reported good long-term results in the occlusion of intracranial aneurysms with flow diverter treatment. The aim of this study was to report the safety and six-month follow-up outcomes using the new Surpass Evolve flow diverter in the treatment of intracranial aneurysms. Materials and methodsConsecutive patients with intracranial aneurysm treated with Surpass Evolve flow diverter in two high-volume neurovascular centers between May 2019 and January 2020 were retrospectively reviewed. Procedure-related complications, aneurysm occlusion (O’Kelly-Marotta grading scale), and clinical outcomes were assessed. ResultsTwenty-nine patients with 30 aneurysms were included in the study. Favorable aneurysm occlusion (O’Kelly Marotta grading scale C-D) at six-month follow-up was achieved in 21/27 (78%) aneurysms. No clinical procedure related thromboembolic complications were encountered. Twenty-three out of 24 patients with unruptured aneurysms treated with Surpass Evolve remained clinically intact at clinical follow-up. There was one fatal hemorrhagic procedure-related complication (3%). In five patients with ruptured aneurysms, no early or late rebleeds occurred from the aneurysms. ConclusionsSurpass Evolve FD worked technically well with no intraprocedural thromboembolic complications and occlusion rates comparable to other FDs.

Limitations of Flow Diverters in Posterior Communicating Artery Aneurysms.

Background: Treatment of intracranial aneurysms with flow diverters (FDs) showed promising results. However, a subset of patients treated for posterior communicating artery (PComA) aneurysms has variable occlusion rates. Especially the fetal type-associated PComA aneurysms seemed to respond differently to treatment. We analyze our series of fetal type PComA aneurysms treated with a FD. The literature on this subject is reviewed. Methods: Data from patients treated with FD for all PComA aneurysms at the RadboudUMC Nijmegen were retrospectively analysed. Primary end-point was complete aneurysm occlusion at six months. Secondary end-points were clinical outcome, treatment safety, and results of secondary treatment after non-closure. The results for the fetal PComA aneurysms were compared to the literature. Results: Nineteen consecutive patients harboring 21 PComA aneurysms were treated. Three aneurysms had ipsilateral fetal type PCA (14.3%). Overall, none of the fetal type PcomA aneurysm showed complete occlusion versus 77.8% of the others (p = 0.03). Mortality and permanent morbidity rates were respectively 5.3% and 0%. Conclusions: FD treatment for PComA aneurysm with fetal type circulation seemed to be less effective compared to other types of PComA aneurysms. Flow characteristics at the PComA bifurcation are thought to be causative Alternative strategies should be considered as first line treatment.

A novel score for evaluating cerebral aneurysms treated with flow diversion: 4F-flow diversion predictive score.

Background and purpose:Although grading scales for angiography outcomes following cerebral aneurysm treatment with flow diversion have been published, physicians have not widely adopted these scales in practice. The aim of this study is to propose and validate a novel Flow diversion Predictive Score (4F-FPS) grading scale based on previously established scales that is simple and reliable.Methods:We retrospectively analyzed consecutive patients who underwent endovascular treatment for cerebral aneurysms with flow diversion between January 2014 and September 2019. The included patients were randomly divided into the derivation and validation group in a 70/30 ratio, respectively. Aneurysms were classified as incomplete or complete occlusion based on final angiography outcomes. 4F-FPS was derived to predict aneurysm occlusion from multivariate logistic regression analyses in the derivation group and validated with previously published grading scales in the validation group.Results:Overall, 662 patients [mean age, 53.8 years; 72.5% (480/662) female] with 662 aneurysms treated with the PipelineTM flow diverter were included [69.9% (463/662) derivation group, 30.1% (199/662) validation group]. The incidence of aneurysm occlusion was 82.7%. 4F-FPS demonstrated significant discrimination in 10-fold cross validation [mean receiver operating characteristic (ROC) area, 0.862 ± 0.055] and calibration (Cox & Snell R2, 0.251; Nagelkerke R2, 0.413) in the derivation group. The ROC area of 4F-FPS score in both the derivation and validation groups is the largest compared with previously published grading scales/scores (p < 0.05), which shows better sensitivity and specificity. The 4F-FPS score showed excellent prediction, discrimination, and calibration properties.Conclusion:The 4F-FPS score is a simple and reliable tool to predict angiography outcome after flow diversion treatment. If widely adopted, it may provide a common language to be used in future reporting of flow diversion results for clinical trials and daily practice.Clinical trial registration:http://www.clinicaltrials.gov. Unique identifier: NCT03831672

Dual-center study comparing transradial and transfemoral approaches for flow diversion treatment of intracranial aneurysms

BACKGROUND:The transfemoral approach (TFA) has been the traditional approach for neurointerventional cases. While the TFA allows for triaxial support in flow diverting stent cases, it is associated with access site complications. Recently, the transradial approach (TRA) has emerged as a safer alternative to the TFA. To the best of our knowledge, there have only been single-center studies comparing outcomes in flow diverter cases for these approaches. We demonstrate the safety and feasibility of the TRA for placement of flow diverting stents in the treatment of unruptured intracranial aneurysms at two high-volume centers.MATERIALS AND METHODS:We performed a retrospective review of prospectively collected institutional databases at two high-volume neuroendovascular centers. Cases from 2016 to 2018 of unruptured intracranial aneurysms treated by flow diverting stenting accessed through either the TRA or the TFA were compared. Patient demographics, procedural and radiographic metrics including location and size of the aneurysm, size, and length of the flow diverter implant, and fluoroscopic time were recorded. Puncture site complications and length of hospital stay were also included in the data analysis.RESULTS:There were three out of 29 TRA cases which were converted to the TFA. None of the TRA patients experienced site complications, whereas three TFA patients experienced site complications. While TRA and TFA patients did not differ significantly in their exposure to radiation, TRA patients experienced shorter hospital stays.CONCLUSIONS:While long-term studies are still lacking regarding this approach, we demonstrate that the TRA is a safe and feasible approach for flow diverter stent placement.

Prophylactic administration of tirofiban for preventing thromboembolic events in flow diversion treatment of intracranial aneurysms

BackgroundFlow diverter (FD) is widely used in the treatment of intracranial aneurysms. However, thromboembolic events (TEs) continue to be the major complications during the periprocedural phase. To evaluate the safety...

Computational Fluid Dynamics Using a Porous Media Setting Predicts Outcome after Flow-Diverter Treatment

Knowledge about predictors of the outcome of flow-diverter treatment is limited. The aim of this study was to predict the angiographic occlusion status after flow-diverter treatment with computational fluid dynamics using porous media modeling for decision-making in the treatment of large wide-neck aneurysms. A total of 27 patients treated with flow-diverter stents were retrospectively analyzed through computational fluid dynamics using pretreatment patient-specific 3D rotational angiography. These patients were classified into no-filling and contrast-filling groups based on the O'Kelly-Marotta scale. The patient characteristics, morphologic variables, and hemodynamic parameters were evaluated for understanding the outcomes of the flow-diverter treatment. The patient characteristics and morphologic variables were similar between the 2 groups. Flow velocity, wall shear stress, shear rate, modified aneurysmal inflow rate coefficient, and residual flow volume were significantly lower in the no-filling group. A novel parameter, called the normalized residual flow volume, was developed and defined as the residual flow volume normalized by the dome volume. The receiver operating characteristic curve analyses demonstrated that the normalized residual flow volume with an average flow velocity of ≥8.0 cm/s in the aneurysmal dome was the most effective in predicting the flow-diverter treatment outcomes. It was established in this study that the hemodynamic parameters could predict the angiographic occlusion status after flow-diverter treatment.

The Hemodynamic Effect of Flow Diverter Treatment of Intracranial Bifurcation Aneurysms

Flow diverter (FD) is a novel technique used for intracranial aneurysms, but the hemodynamic changes caused by FD implantation in bifurcation aneurysms (BAs) are still undefined. Computational fluid dynamics (CFD) were applied to analyze the hemodynamic parameters in a patient-specific basilar artery tip aneurysmal model, which include blood flow velocity, wall shear stress (WSS), aneurysmal wall pressure and branch vessel flow rate. The porous media model was used to simulate three different FD implantation strategies: single FD in a larger branch, single FD in a smaller branch and Y-shaped FD into bilateral branches. The flow velocity inside the aneurysmal sac was decreased by 70.99%, 76.13%, and 69.30% in strategies 1, 2 and 3, respectively. The mean WSS was decreased by 71.9% in Strategy 1, 73.9% in Strategy 2 and 76.1% in Strategy 3. The aneurismal wall pressure was dropped by 8.2% and 7.9% in Strategies 2 and 3, while the pressure was increased by 14.2% in Strategy 1. The velocity of the two small covered branches was dropped by 99.3% and 99.1% in Strategy 1, 10.3% and 7.5% in Strategy 2, and 15.2% and 6.3% in Strategy 3. The porous media model was considered feasible to simulate the implantation strategies of FD in BAs. The reduction velocity and WSS were observed in all FD implantation strategies, indicating the effectiveness of FD treatment in BAs. The blood flow of small covered branch vessels was decreased after FD implantation, suggesting potential risk of occlusion.

Radial access for neurointervention: room set-up and technique for diagnostic angiography

A number of prospective randomized trials have shown that the radial artery is a safer access site than the femoral artery for endovascular procedures.1–4 In the cardiac literature there was...

Stenting as porous media in anatomically accurate geometries. A comparison of models and spatial heterogeneity

Modelling intracranial aneurysm blood flow after flow diverter treatment has proven to be of great scientific and clinical interest. One of the reasons for not having CFD as an everyday clinical tool yet is the time required to set-up such simulations plus the required computational time. The speed-up of these simulations can have a considerable impact during treatment planning and device selection. Modelling flow diverters as a porous medium (PM) can considerably improve the computational time. Many models have been presented in literature, but quantitative comparisons between models are scarce.In this study, the untreated case, the explicit definition of the flow diverter wires as no-slip boundary condition and five different porous medium models were chosen for comparison, and evaluated on intracranial aneurysm of 14 patients with different shapes, sizes, and locations. CFD simulations were made using finite volume method on steady flow conditions. Velocities, kinetic energy, wall shear stress, and computational time were assessed for each model. Then, all models are compared against the no-slip boundary condition using non parametric Kolmogorov–Smirnov test.The model with least performance showed a mean K-S statistic of 0.31 and deviance of 0.2, while the model with best values always gave K-S statistics below 0.2. Kinetic energy between PM models varied between an over estimation of 218.3% and an under estimation of 73.06%. Also, speedups were between 4.75x and 5.3x (stdev: 0.38x and 0.15x) when using PM models.Flow diverters can be simulated with PM with a good agreement to standard CFD simulations were FD wires are represented with no-slip boundary condition in less than a quarter of the time. Best results were obtained on PM models based on geometrical properties, in particular, when using a heterogeneous medium based on equations for flat rhomboidal wire frames.