scholarly journals Computational Study of Hemodynamic Changes Induced by Overlapping and Compacting of Stents and Flow Diverter in Cerebral Aneurysms

2021 ◽  
Vol 12 ◽  
Author(s):  
Sunghan Kim ◽  
Hyeondong Yang ◽  
Ineui Hong ◽  
Je Hoon Oh ◽  
Yong Bae Kim
Keyword(s):  
Computational Study ◽  
Cerebral Aneurysms ◽  
Flow Diverter ◽  
Flow Diversion ◽  
Cfd Analysis ◽  
Hemodynamic Parameters ◽  
Intracranial Stent ◽  
Low Profile ◽  
Computational Fluid Dynamics Cfd ◽  
Aneurysm Model

Purpose: The flow diversion effect of an intracranial stent is closely related to its metal coverage rate (MCR). In this study, the flow diversion effects of Enterprise and low-profile visualized intraluminal support (LVIS) stents are compared with those of a Pipeline flow diverter, focusing on the MCR change. Moreover, the changes in the flow diversion effect caused by the additional manipulations of overlapping and compaction are verified using computational fluid dynamics (CFD) analysis.Methods: CFD analysis was performed using virtually generated stents mounted in an idealized aneurysm model. First, the flow diversion effects of single Enterprise, LVIS, and Pipeline devices were analyzed. The Enterprise and LVIS were sequentially overlapped and compared with a Pipeline, to evaluate the effect of stent overlapping. The effect of compacting a stent was evaluated by comparing the flow diversion effects of a single and two compacted LVIS with those of two overlapped, uncompacted LVIS and uncompacted and compacted Pipeline. Quantitative analysis was performed to evaluate the hemodynamic parameters of energy loss, average velocity, and inflow rate.Results: Statistically significant correlations were observed between the reduction rates of the hemodynamic parameters and MCR. The single LVIS without compaction induced a reduction in all the hemodynamic parameters comparable to those of the three overlapped Enterprise. Moreover, the two overlapped, uncompacted LVIS showed a flow diversion effect as large as that induced by the single uncompacted Pipeline. Compacted stents induced a better flow diversion effect than uncompacted stents. The single compacted LVIS induced a flow diversion effect similar to that induced by the two uncompacted LVIS or single uncompacted Pipeline.Conclusions: The MCR of a stent correlates with its flow diversion effect. Overlapping and compaction can increase the MCR of an intracranial stent and achieve a flow diversion effect as large as that observed with a flow diverter.

Transcirculation Silk Vista Baby-assisted coiling in half-T configuration for the treatment of posterior communicating artery aneurysms associated with a fetal posterior circulation: An alternative flow diversion strategy

2020 ◽  
pp. 159101992096188
Author(s):  
Mario Martínez-Galdámez ◽  
Miguel Schüller-Arteaga ◽  
Jorge Galván-Fernández ◽  
Vladimir Kalousek ◽  
Ezequiel Petra ◽  
...  
Keyword(s):  
Flow Diverter ◽  
Posterior Circulation ◽  
Flow Diversion ◽  
Anterior Communicating Artery ◽  
Anterior Circulation ◽  
Low Profile ◽  
Specific Subgroup ◽  
Flow Diverter Devices ◽  
Profile Flow ◽  
Incomplete Occlusion

Flow diverter devices have become a routine first-line option for treatment of an increasing population of intracranial aneurysms at many neurovascular centers.  Despite the promising results of flow diverter stents on anterior circulation, incomplete occlusion on the presence of fetal posterior circulation has been described on several reports.  Here we describe a novel technical alternative to conventional flow diversion approach for this specific subgroup of aneurysms using the low-profile flow diverter, Silk Vista Baby. The device was selectively placed into the fetal type posterior cerebral artery in half-T configuration for the treatment of a posterior communicating aneurysm using a transcirculation approach through the anterior communicating artery. This represents a useful and effective technique and should be considered when encountering the above-described situation.

scholarly journals A Workflow for Patient-Individualized Virtual Angiogram Generation Based on CFD Simulation

2012 ◽  
Vol 2012 ◽  
pp. 1-24 ◽  
Author(s):  
Jürgen Endres ◽  
Markus Kowarschik ◽  
Thomas Redel ◽  
Puneet Sharma ◽  
Viorel Mihalef ◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stress ◽  
Cfd Simulation ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Hemodynamic Parameters ◽  
Risk Of Rupture ◽  
Computational Fluid Dynamics Cfd ◽  
Subsequent Comparison

Increasing interest is drawn on hemodynamic parameters for classifying the risk of rupture as well as treatment planning of cerebral aneurysms. A proposed method to obtain quantities such as wall shear stress, pressure, and blood flow velocity is to numerically simulate the blood flow using computational fluid dynamics (CFD) methods. For the validation of those calculated quantities, virtually generated angiograms, based on the CFD results, are increasingly used for a subsequent comparison with real, acquired angiograms. For the generation of virtual angiograms, several patient-specific parameters have to be incorporated to obtain virtual angiograms which match the acquired angiograms as best as possible. For this purpose, a workflow is presented and demonstrated involving multiple phantom and patient cases.

scholarly journals Stagnation and complex flow in ruptured cerebral aneurysms: a possible association with hemostatic pattern

2017 ◽  
Vol 126 (5) ◽  
pp. 1566-1572 ◽  
Author(s):  
Masanori Tsuji ◽  
Tatsuya Ishikawa ◽  
Fujimaro Ishida ◽  
Kazuhiro Furukawa ◽  
Yoichi Miura ◽  
...  
Keyword(s):  
Histopathological Examination ◽  
Cerebral Aneurysms ◽  
Hemodynamic Parameters ◽  
Complex Flow ◽  
Aneurysm Wall ◽  
Flow Stagnation ◽  
3D Ct Angiography ◽  
Computational Fluid Dynamics Cfd ◽  
Hematoxylin And Eosin ◽  
Middle Cerebral Artery Aneurysms

OBJECTHistopathological examination has revealed that ruptured cerebral aneurysms have different hemostatic patterns depending on the location of the clot formation. In this study, the authors investigated whether the hemostatic patterns had specific hemodynamic features using computational fluid dynamics (CFD) analysis.METHODSTwenty-six ruptured middle cerebral artery aneurysms were evaluated by 3D CT angiography and harvested at the time of clipping. The hemostatic patterns at the rupture points were assessed by means of histopathological examination, and morphological parameters were obtained. Transient analysis was performed, and wall shear stress–related hemodynamic parameters and invariant Q (vortex core region) were calculated. The morphological and hemodynamic parameters were compared among the hemostatic patterns.RESULTSHematoxylin and eosin staining of the aneurysm wall showed 13 inside-pattern, 9 outside-pattern, and 4 other-pattern aneurysms. Three of the 26 aneurysms were excluded from further analysis, because their geometry models could not be generated due to low vascular CT values. Mann-Whitney U-tests showed that lower dome volume (0.04 cm3 vs 0.12 cm3, p = 0.014), gradient oscillatory number (0.0234 vs 0.0289, p = 0.023), invariant Q (−0.801 10−2/sec2 vs −0.124 10−2/sec2, p = 0.045) and higher aneurysm formation indicator (0.986 vs 0.963, p = 0.041) were significantly related to inside-pattern aneurysms when compared with outside-pattern aneurysms.CONCLUSIONSInside-pattern aneurysms may have simpler flow patterns and less flow stagnation than outside-pattern aneurysms. CFD may be useful to characterize the hemostatic pattern of ruptured cerebral aneurysms.

scholarly journals Influence of different computational approaches for stent deployment on cerebral aneurysm haemodynamics

2011 ◽  
Vol 1 (3) ◽  
pp. 338-348 ◽  
Author(s):  
Annarita Bernardini ◽  
Ignacio Larrabide ◽  
Hernán G. Morales ◽  
Giancarlo Pennati ◽  
Lorenza Petrini ◽  
...  
Keyword(s):  
Cerebral Aneurysm ◽  
Cerebral Aneurysms ◽  
Cfd Analysis ◽  
Clinical Workflow ◽  
Stent Deployment ◽  
Cerebral Vessel ◽  
Virtual Tools ◽  
Computational Fluid Dynamics Cfd ◽  
Vessel Material ◽  
Set Up

Cerebral aneurysms are abnormal focal dilatations of artery walls. The interest in virtual tools to help clinicians to value the effectiveness of different procedures for cerebral aneurysm treatment is constantly growing. This study is focused on the analysis of the influence of different stent deployment approaches on intra-aneurysmal haemodynamics using computational fluid dynamics (CFD). A self-expanding stent was deployed in an idealized aneurysmatic cerebral vessel in two initial positions. Different cases characterized by a progression of simplifications on stent modelling (geometry and material) and vessel material properties were set up, using finite element and fast virtual stenting methods. Then, CFD analysis was performed for untreated and stented vessels. Haemodynamic parameters were analysed qualitatively and quantitatively, comparing the cases and the two initial positions. All the cases predicted a reduction of average wall shear stress and average velocity of almost 50 per cent after stent deployment for both initial positions. Results highlighted that, although some differences in calculated parameters existed across the cases based on the modelling simplifications, all the approaches described the most important effects on intra-aneurysmal haemodynamics. Hence, simpler and faster modelling approaches could be included in clinical workflow and, despite the adopted simplifications, support clinicians in the treatment planning.

Abstract 1122‐000158: Flow Diversion of Cerebral Aneurysms via Direct Carotid Artery Cutdown: A Case Series

2021 ◽  
Vol 1 (S1) ◽  
Author(s):  
Yahia M Lodi ◽  
Varun V Reddy ◽  
Adam Cloud ◽  
Zara T Lodi ◽  
Ravi Pande
Keyword(s):  
Carotid Artery ◽  
Case Series ◽  
Cerebral Aneurysms ◽  
Flow Diverter ◽  
Flow Diversion ◽  
Vascular Surgeon ◽  
Clinical Events ◽  
History Of ◽  
Severity Of The Disease ◽  
Arch Aneurysm

Introduction : Flow diversion (FD) of the cerebral aneurysms (CA) are performed either by trans femoral or transradial approach. Safety and feasibility of an alternative option such as direct Carotid artery Cutdown (DCAC) and FD for the treatment of the CA in a situation when tradition approaches are not feasible is not well described. Methods : Retrospective review. Results : First patient; 67 years old man with history of hypertension, hyperlipidemia, smoking, and stenting of the aortic arch aneurysm was diagnosed with symptomatic bilateral ICA DSA buy a CT angiography. Right ICA DSA was in multi‐level extending from cervical carotid artery to the skull base measured 19 × 15 × 20 mm and the left was 16 × 9 × 22 mm. Considering the severity of the disease and the presence of symptoms, planned for a DCAC by vascular surgeon followed by FD by neurovascular surgeon (NES) in a staged fashion. A 6F sheath was placed from right common carotid artery (CCA) to right ICA by a vascular surgeon. A CAT5 catheter was navigated to the ICA beyond DSA. FD was achieved using Surpass streamline measuring 4 × 50 mm x2 and a 5 × 40 mm. The DCAC site was sutured by vascular surgeon and patient was extubated. Using similar techniques, Left‐sided DPA was repaired using 5 × 50 mm surpass streamline flow diverter in 3 months. Second patient; 75 years old women’s let ICA opththalmic (ICA‐O) aneurysm grown from 8 mm to 12 mm with headaches. TF and TR approaches failed, underwent DCAC and FD with pipeline flex (PF) 5 × 30 mm using phenom plus and phenom XT27 microcatheter. Third patient; 65 years old women with LICA‐0 9 mm symptomatic aneurysm with occlusions femoral and radial arteries due to smoking underwent FD with PF of 4 × 30 mm. There were no clinical events, first patient’s right ICA radiographic dissection was repaired by VS prior to extubation. Patients were discharged home in 48 hours with NIHSS 0 and achieved baseline mRS. Patients were continued full antiplatelets for six months followed by an 81 mg baby aspirin and 75 mg of clopidogrel. Follow‐up MR angiogram demonstrate complete obligations of the aneurysms without stenosis. Conclusions : Our case series demonstrate that DCAC for the FD of the intracranial aneurysm is feasible and safe when performed carefully and in coordination with a multidisciplinary team. Further studies are required.

scholarly journals Validation of CFD Simulations of Cerebral Aneurysms With Implication of Geometric Variations

2006 ◽  
Vol 128 (6) ◽  
pp. 844-851 ◽  
Author(s):  
Yiemeng Hoi ◽  
Scott H. Woodward ◽  
Minsuok Kim ◽  
Dale B. Taulbee ◽  
Hui Meng
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Cerebral Aneurysms ◽  
Patient Specific ◽  
Hemodynamic Parameters ◽  
Cfd Simulations ◽  
Piv Measurements ◽  
Cfd Method ◽  
Aneurysm Model

Background. Computational fluid dynamics (CFD) simulations using medical-image-based anatomical vascular geometry are now gaining clinical relevance. This study aimed at validating the CFD methodology for studying cerebral aneurysms by using particle image velocimetry (PIV) measurements, with a focus on the effects of small geometric variations in aneurysm models on the flow dynamics obtained with CFD. Method of Approach. An experimental phantom was fabricated out of silicone elastomer to best mimic a spherical aneurysm model. PIV measurements were obtained from the phantom and compared with the CFD results from an ideal spherical aneurysm model (S1). These measurements were also compared with CFD results, based on the geometry reconstructed from three-dimensional images of the experimental phantom. We further performed CFD analysis on two geometric variations, S2 and S3, of the phantom to investigate the effects of small geometric variations on the aneurysmal flow field. Results. We found poor agreement between the CFD results from the ideal spherical aneurysm model and the PIV measurements from the phantom, including inconsistent secondary flow patterns. The CFD results based on the actual phantom geometry, however, matched well with the PIV measurements. CFD of models S2 and S3 produced qualitatively similar flow fields to that of the phantom but quantitatively significant changes in key hemodynamic parameters such as vorticity, positive circulation, and wall shear stress. Conclusion. CFD simulation results can closely match experimental measurements as long as both are performed on the same model geometry. Small geometric variations on the aneurysm model can significantly alter the flow-field and key hemodynamic parameters. Since medical images are subjected to geometric uncertainties, image-based patient-specific CFD results must be carefully scrutinized before providing clinical feedback.

Transradial approach for flow diversion treatment of cerebral aneurysms: a multicenter study

2019 ◽  
Vol 11 (8) ◽  
pp. 796-800 ◽  
Author(s):  
Stephanie H Chen ◽  
Brian M Snelling ◽  
Sumedh Subodh Shah ◽  
Samir Sur ◽  
Marie Christine Brunet ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Cerebral Aneurysms ◽  
High Volume ◽  
Flow Diverter ◽  
Acute Angle ◽  
Flow Diversion ◽  
Left Internal Carotid Artery ◽  
Access Site ◽  
Transradial Approach ◽  
Aneurysm Treatment

BackgroundThe transradial approach (TRA) to endovascular procedures decreases access site morbidity and mortality in comparison with the traditional transfemoral technique (TFA). Despite its improved safety profile, there is a concern that TRA is less favorable for neurointerventional procedures that require large coaxial systems to manage the small tortuous cerebral vessels.ObjectiveTo report our experience with TRA for flow diverter placement for treatment of unruptured cerebral aneurysms.MethodsWe performed a retrospective review of prospective institutional databases at two high-volume centers to identify 49 patients who underwent flow diversion for aneurysm treatment via primary TRA between November 2016 and November 2018. Patient demographics, procedural techniques, and clinical data were recorded.ResultsOf the 49 patients, 39 underwent successful flow diversion placement by TRA. Ten patients were converted to TFA after attempted TRA. There were no procedural complications. Reasons for failure included tortuosity in eight patients and severe radial artery spasm in two.ConclusionsIn the largest reported series to date of flow diverter deployment via TRA for aneurysm treatment, we demonstrate the technical feasibility and safety of the method. The most common reason for failure of TRA was an acute angle of left common carotid artery origin or left internal carotid artery tortuosity. Overall, our data suggest that increasing adoption of TRA is merited given its apparent equivalence to the current TFA technique and its documented reduction in access site complications.

scholarly journals GP.3 Examining Aneurysmal Healing After Flow Diversion Treatment Using Endovascular Optical Coherence Tomography

2021 ◽  
Vol 48 (s3) ◽  
pp. S12-S13
Author(s):  
CR Pasarikovski ◽  
J Ku ◽  
J Ramjist ◽  
Y Dobashi ◽  
SM Priola ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Cerebral Aneurysms ◽  
Cell Loss ◽  
Flow Diversion ◽  
Optical Coherence ◽  
Parent Vessel ◽  
Novel Technology ◽  
New Zealand White Rabbits ◽  
Aneurysm Model ◽  
Elastic Lamina

Background: The mechanism of aneurysmal healing after flow-diversion treatment of cerebral aneurysms remains unknown. The purpose of this research to is to utilize a novel technology called endovascular optical coherence tomography (OCT) to characterise and improve our understanding of aneurysmal healing after flow-diversion using a rabbit aneurysm model. Methods: Saccular aneurysms were created in 10 New Zealand white rabbits. The aneurysms were treated with a flow-diverting stent 28 days after creation. OCT and histopathologic examinations included: luminal thrombosis, endothelial loss, inflammation, fibrin, smooth muscle cell loss, disruption of the internal and external elastic lamina, and tunica adventitia changes Results: OCT revealed endothelialization across the stent, appearing to originate from the parent vessel, along with small amounts of thrombus on the stent-struts. Minimal thrombus was visualized within the aneurysm sac. Histologic examination revealed that OCT can accurately define endothelialization across the sent, and define patent segments across the neck. Conclusions: Aneurysmal healing appears to originate at the parent vessel/stent interface, and use the stent as a scaffold to grow across the neck of the aneurysm. Minimal thrombus was visualized within the aneurysm sac, with ongoing flow observed in the setting of incomplete neck endothelialization. This technology has great potential for assessing aneurysmal healing in real-time.

scholarly journals In-silico trial of intracranial flow diverters replicates and expands insights from conventional clinical trials

2021 ◽  
Author(s):  
Ali Sarrami-Foroushani ◽  
Toni Lassila ◽  
Michael Macraild ◽  
Joshua Asquith ◽  
Kit C. B. Roes ◽  
...  
Keyword(s):  
Clinical Trials ◽  
In Silico ◽  
Flow Diverter ◽  
Flow Diversion ◽  
Virtual Experiments ◽  
Flow Reduction ◽  
Trial Endpoints ◽  
Computational Fluid Dynamics Cfd ◽  
The Cost ◽  
Flow Diverting Stent

Abstract Although the cost of clinical trials is ever-increasing, in-silico trials, which rely on virtual populations and interventions simulated using patient-specificc models, may offer a solution to contain these costs. However, in-silico trial endpoints need to be compared to those available from conventional clinical trials to ensure that the predictions of safety or effcacy from the in-silico approach are valid. Here, we present the flow diverter performance assessment (FDPASS) in-silico trial, which modelled the treatment of intracranial aneurysms in 82 virtual patients with a flow-diverting stent, using computational fluid dynamics (CFD) to quantify post-treatment flow reduction in the aneurysm sac. The predicted FD-PASS flow-diversion success rate replicated the values previously reported in three reference clinical trials. The in-silico approach allowed broader investigation of factors associated with insuficient flow reduction and increased stroke risk after flow diversion than would be feasible in a conventional trial. These ndings demonstrate for the rst time that in-silico trials of medical devices can (i) replicate ndings of conventional clinical trials and (ii) incorporate virtual experiments that are impossible in conventional trials.

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