scholarly journals High-fidelity virtual stenting: modeling of flow diverter deployment for hemodynamic characterization of complex intracranial aneurysms

2015 ◽  
Vol 123 (4) ◽  
pp. 832-840 ◽  
Author(s):  
Jianping Xiang ◽  
Robert J. Damiano ◽  
Ning Lin ◽  
Kenneth V. Snyder ◽  
Adnan H. Siddiqui ◽  
...  
Keyword(s):  
Intracranial Aneurysms ◽  
Average Velocity ◽  
Vascular Anatomy ◽  
Flow Diverter ◽  
Turnover Time ◽  
High Fidelity ◽  
Inflow Rate ◽  
Proof Of Concept ◽  
Flow Reduction

OBJECT Flow diversion via Pipeline Embolization Device (PED) represents the most recent advancement in endovascular therapy of intracranial aneurysms. This exploratory study aims at a proof of concept for an advanced device-modeling tool in conjunction with computational fluid dynamics (CFD) to evaluate flow modification effects by PED in actual, treated cases. METHODS The authors performed computational modeling of 3 PED-treated complex aneurysm cases. The patient in Case 1 had a fusiform vertebral aneurysm treated with a single PED. In Case 2 the patient had a giant internal carotid artery (ICA) aneurysm treated with 2 PEDs. Case 3 consisted of tandem ICA aneurysms (III-a and III-b) treated by a single PED. The authors’ recently developed high-fidelity virtual stenting (HiFiVS) technique was used to recapitulate the clinical deployment process of PEDs in silico for these 3 cases. Pretreatment and posttreatment aneurysmal hemodynamics studies performed using CFD simulation were analyzed. Changes in aneurysmal flow velocity, inflow rate, wall shear stress (WSS), and turnover time were calculated and compared with the clinical outcome. RESULTS In Case 1 (occluded within the first 3 months), the aneurysm had the most drastic flow reduction after PED placement; the aneurysmal average velocity, inflow rate, and average WSS were decreased by 76.3%, 82.5%, and 74.0%, respectively, whereas the turnover time was increased to 572.1% of its pretreatment value. In Case 2 (occluded at 6 months), aneurysmal average velocity, inflow rate, and average WSS were decreased by 39.4%, 38.6%, and 59.1%, respectively, and turnover time increased to 163.0%. In Case 3, Aneurysm III-a (occluded at 6 months) had a decrease by 38.0%, 28.4%, and 50.9% in average velocity, inflow rate, and average WSS, respectively, and turnover time increased to 139.6%, which was quite similar to Aneurysm II. Surprisingly, the adjacent Aneurysm III-b had more substantial flow reduction (a decrease by 77.7%, 53.0%, and 84.4% in average velocity, inflow rate, and average WSS, respectively, and an increase to 213.0% in turnover time) than Aneurysm III-a, which qualitatively agreed with angiographic observation at 3-month follow-up. However, Aneurysm III-b remained patent at both 6 months and 9 months. A closer examination of the vascular anatomy in Case 3 revealed blood draining to the ophthalmic artery off Aneurysm III-b, which may have prevented its complete thrombosis. CONCLUSIONS This proof-of-concept study demonstrates that HiFiVS modeling of flow diverter deployment enables detailed characterization of hemodynamic alteration by PED placement. Posttreatment aneurysmal flow reduction may be correlated with aneurysm occlusion outcome. However, predicting aneurysm treatment outcome by flow diverters also requires consideration of other factors, including vascular anatomy.

Hemodynamic differences between Pipeline and coil-adjunctive intracranial stents

2019 ◽  
Vol 11 (9) ◽  
pp. 908-911 ◽  
Author(s):  
Brian Thomas Jankowitz ◽  
Bradley A Gross ◽  
Santhosh Seshadhri ◽  
Gaurav Girdhar ◽  
Ashutosh Jadhav ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Metal Surface ◽  
Velocity Vector ◽  
Surface Coverage ◽  
Flow Analysis ◽  
Flow Diverter ◽  
Turnover Time ◽  
Inflow Rate ◽  
Wall Shear

IntroductionModern coil-adjunctive intracranial stent designs have increased metal surface coverage to construct putative ‘flow diverter lights.’ This is rooted in the assumption that flow diversion is linearly correlated with metal surface coverage rather than being a threshold to be reached by device porosity and design.ObjectiveTo evaluate this assumption, by performing computational flow analysis on three aneurysm models treated with low metal surface coverage stents (ATLAS and Enterprise), a Pipeline flow diverter, and the LVIS Blue stent.MethodsComputational flow analysis was performed on virtual deployment models entailing deployment of an ATLAS, Enterprise, LVIS Blue, or Pipeline. The impact of device deployment on velocity vectors at the neck, maximum wall shear stress, inflow rate into the aneurysm, and turnover time was determined.ResultsVelocity vector plots demonstrated low magnitude, localized inflow jets for Pipeline only; asymmetric, selectively high inflow jets were seen for LVIS Blue, and broader velocity vector clusters were seen for Atlas and Enterprise. Reduction in wall shear stress as compared with baseline was significant for all devices and greatest for the Pipeline. Mean peak wall shear stress was significantly lower for LVIS Blue in comparison with ATLAS or Enterprise but significantly lower for Pipeline than for LVIS Blue. Reduction of inflow rate into the aneurysm was significant for LVIS Blue and Pipeline but significantly lower for Pipeline than for LVIS Blue. Turnover time was statistically similar for ATLAS, Enterprise, and LVIS Blue, but significantly increased for Pipeline.ConclusionConsiderable differences in peak wall shear stress, inflow rates, and turnover time between flow diverters, moderate- and low-porosity stents reinforce the assumption that effective flow diversion represents a threshold in device design, encompassing metal surface coverage only in part.

Increasing Flow Diversion for Cerebral Aneurysm Treatment Using a Single Flow Diverter

Neurosurgery ◽  
2014 ◽  
Vol 75 (3) ◽  
pp. 286-294 ◽  
Author(s):  
Jianping Xiang ◽  
Ding Ma ◽  
Kenneth V. Snyder ◽  
Elad I. Levy ◽  
Adnan H. Siddiqui ◽  
...  
Keyword(s):  
Shear Stress ◽  
Cerebral Aneurysms ◽  
Flow Diverter ◽  
Turnover Time ◽  
Patient Specific ◽  
Uniform Mesh ◽  
Mesh Structure ◽  
Flow Reduction ◽  
Flow Stasis ◽  
Single Flow

Abstract BACKGROUND: A neurovascular flow diverter (FD), aiming at inducing embolic occlusion of cerebral aneurysms through hemodynamic changes, can produce variable mesh densities owing to its flexible mesh structure. OBJECTIVE: To explore whether the hemodynamic outcome would differ by increasing FD local compaction across the aneurysm orifice. METHODS: We investigated deployment of a single FD using 2 clinical strategies: no compaction (the standard method) and maximum compaction across the aneurysm orifice (an emerging strategy). Using an advanced modeling technique, we simulated these strategies applied to a patient-specific wide-necked aneurysm model, resulting in a relatively uniform mesh with no compaction (C1) and maximum compaction (C2) at the aneurysm orifice. Pre- and posttreatment aneurysmal hemodynamics were analyzed using pulsatile computational fluid dynamics. Flow-stasis parameters and blood shear stress were calculated to assess the potential for aneurysm embolic occlusion. RESULTS: Flow streamlines, isovelocity, and wall shear stress distributions demonstrated enhanced aneurysmal flow reduction with C2. The average intra-aneurysmal flow velocity was 29% of pretreatment with C2 compared with 67% with C1. Aneurysmal flow turnover time was 237% and 134% of pretreatment for C2 and C1, respectively. Vortex core lines and oscillatory shear index distributions indicated that C2 decreased the aneurysmal flow complexity more than C1. Ultrahigh blood shear stress was observed near FD struts in inflow region for both C1 and C2. CONCLUSION: The emerging strategy of maximum FD compaction can double aneurysmal flow reduction, thereby accelerating aneurysm occlusion. Moreover, ultrahigh blood shear stress was observed through FD pores, which could potentially activate platelets as an additional aneurysmal thrombosis mechanism.

scholarly journals Characterization of design grammar of peptides for regulating liquid droplets and aggregates of FUS

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Kiyoto Kamagata ◽  
Rika Chiba ◽  
Ichiro Kawahata ◽  
Nanako Iwaki ◽  
Saori Kanbayashi ◽  
...  
Keyword(s):  
Amino Acid ◽  
Electrostatic Interactions ◽  
Amyloid Fibrils ◽  
Droplet Formation ◽  
Liquid Droplets ◽  
Proof Of Concept ◽  
Aggregate Formation ◽  
Fused In Sarcoma ◽  
Dynamics Simulations

AbstractLiquid droplets of aggregation-prone proteins, which become hydrogels or form amyloid fibrils, are a potential target for drug discovery. In this study, we proposed an experiment-guided protocol for characterizing the design grammar of peptides that can regulate droplet formation and aggregation. The protocol essentially involves investigation of 19 amino acid additives and polymerization of the identified amino acids. As a proof of concept, we applied this protocol to fused in sarcoma (FUS). First, we evaluated 19 amino acid additives for an FUS solution and identified Arg and Tyr as suppressors of droplet formation. Molecular dynamics simulations suggested that the Arg additive interacts with specific residues of FUS, thereby inhibiting the cation–π and electrostatic interactions between the FUS molecules. Second, we observed that Arg polymers promote FUS droplet formation, unlike Arg monomers, by bridging the FUS molecules. Third, we found that the Arg additive suppressed solid aggregate formation of FUS, while Arg polymer enhanced it. Finally, we observed that amyloid-forming peptides induced the conversion of FUS droplets to solid aggregates of FUS. The developed protocol could be used for the primary design of peptides controlling liquid droplets and aggregates of proteins.

scholarly journals Flow diverter stents in the treatment of recanalized intracranial aneurysms

2021 ◽  
pp. 159101992199050
Author(s):  
Erol Akgul ◽  
Hasan Bilen Onan ◽  
Irem Islek ◽  
Mehmet Tonge ◽  
Yavuz Durmus ◽  
...  
Keyword(s):  
Intracranial Aneurysms ◽  
Demographic Data ◽  
Previous Treatment ◽  
Flow Diverter ◽  
Serious Adverse Events ◽  
Clinical Complications ◽  
Tertiary Hospitals ◽  
The Mean ◽  
Technical Complication

Background We assessed the safety and efficacy of flow diverter stents (FDSs) in the treatment of recanalized or residual intracranial aneurysms treated endovascularly. Materials & Methods Patients whose recanalized or residual aneurysms were treated with FDSs in five tertiary hospitals were reviewed retrospectively. The patients’ demographic data, aneurysm characteristics, types of previous treatment, and clinical complications, or serious adverse events associated with FDSs, as well as the results of neurological and angiographic follow-up assessments, were recorded. Results Eighty-six patients (37 males) with 87 aneurysms were included in this study. Eighty (91.9%) aneurysms were in the anterior and seven (8.1%) in the posterior circulation. The initial treatment methods were the primary coiling or balloon remodeling technique in 69 (79.3%) and stent-assisted coiling in 18 (20.7%) aneurysms. The endovascular procedure was successful in all patients. Complications occurred in four patients, for a total complication rate of 4.6%. A technical complication developed in one patient (1.2%). An in-stent thrombosis treated with tirofiban was seen in two cases. Late in-stent stenosis exceeding 50% was treated with balloon angioplasty in one patient. The mean length of follow-up was 21.0 months. The first angiographic follow-up (3–6 months) revealed the complete occlusion of 74 aneurysms (85.1%). While 76 aneurysms (87.4%) were occluded at the last angiographic follow-up (mean: 26.0 months), 11 aneurysms (12.6%) were still filling. Morbimortality was zero. Conclusion The drawback of endovascular treatment is aneurysmal remnants or recurrences, which is safely and durably amenable to flow diversion.

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

2021 ◽  
pp. neurintsurg-2021-017641
Author(s):  
Kemal Alpay ◽  
Tero Hinkka ◽  
Antti E Lindgren ◽  
Juha-Matti Isokangas ◽  
Rahul Raj ◽  
...  
Keyword(s):  
Mortality Rate ◽  
Intracranial Aneurysms ◽  
Aneurysmal Subarachnoid Hemorrhage ◽  
Flow Diverter ◽  
Supporting Evidence ◽  
Complication Rates ◽  
Related Complication ◽  
Anterior Circulation ◽  
Clinical And Radiological Results ◽  
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 largest series to date.MethodsThis is a nationwide retrospective study of acutely ruptured IAs treated with flow diverters (FDs). The primary outcome was the modified Rankin Scale (mRS) score at the last available follow-up time. Secondary outcomes were treatment-related complications and the aneurysm occlusion rate.Results110 patients (64 females; mean age 55.7 years; range 12–82 years) with acutely ruptured IAs were treated with FDs between 2012 and 2020 in five centers. 70 acutely ruptured IAs (64%) were located in anterior circulation, and 47 acutely ruptured IAs (43%) were blister-like. A favorable functional outcome (mRS 0–2) was seen in 73% of patients (74/102). Treatment-related complications were seen in 45% of patients (n=49). Rebleeding was observed in 3 patients (3%). The data from radiological follow-ups were available for 80% of patients (n=88), and complete occlusion was seen in 90% of aneurysms (79/88). The data from clinical follow-ups were available for 93% of patients (n=102). The overall mortality rate was 18% (18/102).ConclusionsFD treatment yields high occlusion for acutely ruptured IAs but is associated with a high risk of complications. Considering the high mortality rate of aneurysmal subarachnoid hemorrhage, the prevention of rebleeding is crucial. Thus, FD treatment may be justified as a last resort option.

scholarly journals Safety and efficacy results of the Flow Redirection Endoluminal Device (FRED) stent system in the treatment of intracranial aneurysms: US pivotal trial

2021 ◽  
pp. neurintsurg-2021-017469
Author(s):  
Cameron G McDougall ◽  
Orlando Diaz ◽  
Alan Boulos ◽  
Adnan H Siddiqui ◽  
Justin Caplan ◽  
...  
Keyword(s):  
Intracranial Aneurysms ◽  
Flow Diverter ◽  
Multicenter Trial ◽  
Parent Artery ◽  
Stent System ◽  
Safety Endpoint ◽  
Performance Benchmarks ◽  
Registration Number ◽  
The Usa ◽  
Effectiveness Endpoint

ObjectiveTo evaluate the safety and effectiveness of the Flow Redirection Endoluminal Device (FRED) flow diverter in support of an application for Food and Drug Administration approval in the USA.Methods145 patients were enrolled in a prospective, single-arm multicenter trial. Patients with aneurysms of unfavorable morphology for traditional endovascular therapies (large, wide-necked, fusiform, etc) were included. The trial was designed to demonstrate non-inferiority in both safety and effectiveness, comparing trial results with performance goals (PGs) established from peer-reviewed published literature. The primary safety endpoint was death or major stroke (National Institutes of Health Stroke Scale score ≥4 points) within 30 days of the procedure, or any major ipsilateral stroke or neurological death within the first year. The primary effectiveness endpoint was complete occlusion of the target aneurysm with ≤50% stenosis of the parent artery at 12 months after treatment, and in which an alternative treatment of the target intracranial aneurysm had not been performed.Results145 patients underwent attempted placement of a FRED device, and one or more devices were placed in all 145 patients. 135/145 (93%) had a single device placed. Core laboratory adjudication deemed 106 (73.1%) of the aneurysms large or giant. A safety endpoint was experienced by 9/145 (6.2%) patients, successfully achieving the safety PG of <15%. The effectiveness PG of >46% aneurysm occlusion was also achieved, with the effectiveness endpoint being met in 80/139 (57.6%)ConclusionAs compared with historically derived performance benchmarks, the FRED flow diverter is both safe and effective for the treatment of appropriately selected intracranial aneurysms.Clinical registration numberNCT01801007

Flow redirection endoluminal device (FRED) for treatment of intracranial aneurysms: A systematic review

2021 ◽  
pp. 159101992110279
Author(s):  
Muhammad Waqas ◽  
Rimal H Dossani ◽  
Modhi Alkhaldi ◽  
Jocelyn Neveu ◽  
Justin M Cappuzzo ◽  
...  
Keyword(s):  
Systematic Review ◽  
Intracranial Aneurysms ◽  
Flow Diverter ◽  
Complication Rates ◽  
Mesh Terms ◽  
Aneurysm Occlusion ◽  
Occlusion Rate ◽  
Layered Flow ◽  
Comparative Safety

Introduction The Flow Redirection Endoluminal Device (FRED; MicroVention) is a dual-layered flow diverter used for the treatment of intracranial aneurysms. The objective of this systematic review was to compile device-related safety and effectiveness data. Methods The literature from January 1, 2013 to April 30, 2021 was searched for studies describing use of the FRED for intracranial aneurysm treatment irrespective of aneurysm location and morphology. The review included anterior and posterior circulation ruptured and unruptured saccular, fusiform or dissection, and blister aneurysms. MeSH terms related to “flow re-direction endoluminal device” and “FRED for aneurysms” were used. Data related to indication, complications, and rates of aneurysm occlusion were retrieved and analyzed. Results Twenty-two studies with 1729 intracranial aneurysms were included in this review. Overall reported morbidity was 3.9% (range 0–20%). Overall procedure-related mortality was 1.4% (range 0–6%). Complication rates fell into 5 categories: technical (3.6%), ischemic (3.8%), thrombotic or stenotic (6%), hemorrhagic (1.5%), and non-neurological (0.8%). The aneurysm occlusion rate between 0 and 3 months (reported in 11 studies) was 47.8%. The occlusion rate between 4 and 6 months (reported in 14 studies) was 73.8%. Occlusion rates continued to increase to 75.1% at 7–12 months (reported in 10 studies) and 86.6% for follow-up beyond 1 year (reported in 10 studies). Conclusion This review indicated that the FRED is a safe and effective for the treatment of intracranial aneurysms. Future studies should directly compare the FRED with other flow diverters for a better understanding of comparative safety and effectiveness among the different devices.

Abstract 120: Surpass Flow Diverter for Endovascular Treatment of Intracranial Aneurysms - A Multicenter Preliminary Clinical and Angiographic Experience in 161 Patients with 186 Aneurysms

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Ajay K Wakhloo ◽  
Pedro Lylyk ◽  
Joost de Vries ◽  
Matthew J Gounis ◽  
Alexandra Biondi ◽  
...  
Keyword(s):  
Intracranial Aneurysms ◽  
Experimental Studies ◽  
Flow Diverter ◽  
Posterior Circulation ◽  
Parent Artery ◽  
Anterior Circulation ◽  
Neck Size ◽  
Wide Range ◽  
New Generation

Objective: Validated through experimental studies a new generation of flow diverters (Surpass™ FD) was evaluated for treatment of intracranial aneurysms (IA). We present our multicenter preliminary clinical and angiographic experience. METHODS: To achieve the calculated flow disruption between the parent artery and aneurysm for thrombosis, single FDs were placed endovascularly in parent arteries. Implants measured 2.5-5.3mm in diameter with a length of 10-80mm. Patients were enrolled harboring a wide range large and giant wide-neck, fusiform and multiple small and blister-type aneurysm. Clinical and angiographic follow-up were performed at 1-3, 6, and 12 months. RESULTS: A total of 186 consecutive IA in 161 patients (mean age 57.1 years) were treated at 33 centers. Fifty-three aneurysms were smaller than 5 mm, 64 were 5-9.9mm in diameter, 47 were 10-20mm in diameter, and 22 were larger than 20mm (10.4±0.7mm, neck size 6.0±0.5mm [mean±SEM]) . The aneurysms originated in 63.4% from the internal carotid artery; 22% and 14.5% of the lesions were located in the anterior circulation distal to Circle of Willis and posterior circulation respectively. Technical success was achieved in 182 aneurysms (98%); average number of devices used per aneurysm was 1.05. Permanent morbidity and mortality during the follow-up period of mean 8.4months (range 1-24 months) including periprocedural complications for patients with aneurysms of the anterior circulation were encountered in 5 (3.7%) and 2 (1.5 %) patients respectively and 1 (3.7%) and 4 (14.8%) respectively for patients with aneurysms of the posterior circulation location. One-hundred-ten patients (70.5%) harboring 127 (70.2%) were available for clinical and angiographic follow-up and showed a complete or near complete aneurysm occlusion in 63 (81.8%) of the ICA. Aneurysms of the ICA≥10mm that were completely covered by FD and not previously stent-treated with a minimum of 6 months follow-up available in 16 patients showed a complete obliteration in 81.3% (n=13) and >90% occlusion in remaining 3 patients. CONCLUSION: Preliminary data demonstrate high safety and efficacy of a new generation of FD for a wide range of IA of the anterior and posterior circulation with a single implant.

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