scholarly journals Hydrodynamical evaluation of microporous covered stent for the treatment of intracranial aneurysms: Comparison of flow reduction property with flow diverter stent by using particle imaging velocimetry and in vitro flow simulator

2018 ◽  
Vol 32 (1) ◽  
pp. 20-25
Author(s):  
Takeshi Moriwaki ◽  
Tsutomu Tajikawa ◽  
Yasuhide Nakayama
Keyword(s):  
Intracranial Aneurysms ◽  
Flow Diverter ◽  
Covered Stent ◽  
Particle Imaging Velocimetry ◽  
Flow Reduction ◽  
Flow Diverter Stent ◽  
Reduction Property ◽  
Particle Imaging ◽  
Flow Simulator

scholarly journals Role of distal cerebral vasculature in vessel constriction after aneurysm treatment with flow diverter stents

2020 ◽  
Vol 12 (8) ◽  
pp. 818-826
Author(s):  
Ana Paula Narata ◽  
Fernando Moura ◽  
Ignacio Larrabide ◽  
René Chapot ◽  
Christophe Cognard ◽  
...  
Keyword(s):  
Clinical Outcome ◽  
Vascular Resistance ◽  
Intracranial Aneurysms ◽  
Demographic Data ◽  
Power Doppler ◽  
Flow Diverter ◽  
Specific Model ◽  
Patient Specific ◽  
Flow Diverter Stent

BackgroundTreatment of intracranial aneurysms with flow diverter stent (FDS) procedures can lead to caliber changes of jailed vessels. The reason some branches remain unchanged and others are affected by narrowing remains unknown.ObjectiveTo investigate the influence of resistance to flow from distal vasculature on stent-induced hemodynamic modifications affecting bifurcating vessels.Materials and methodsRadiological images and demographic data were acquired for 142 aneurysms treated with a FDS. Vascular resistance was estimated from patient-specific anatomic data. Correlation analysis was used to identify correspondence between anatomic data and clinical outcome. Computational Fluid Dynamics was performed on a typical patient-specific model to evaluate the influence of FDS on flow. Relevant hemodynamic variables along the bifurcating vessels were quantitatively analyzed and validated with in vitro data obtained using power Doppler ultrasound.ResultsStatistical analysis showed a correlation between clinical outcome and FDS resistance to flow considering overall jailed vessel vascular resistance (r=0.5, P<0.001). Computational predictions of blood flow showed that hemodynamics is minimally affected by FDS treatment in the ophthalmic artery.ConclusionsJailed vessels are affected by narrowing when resistance to flow from the FDS constitutes a larger proportion of the overall vessel resistance to flow. This knowledge may contribute to better understanding of intracranial hemodynamics after a FDS procedure and reinforce indications for flow diversion in the treatment of intracranial aneurysms.

scholarly journals Selection of helical braided flow diverter stents based on hemodynamic performance and mechanical properties

2016 ◽  
Vol 9 (10) ◽  
pp. 999-1005 ◽  
Author(s):  
Takashi Suzuki ◽  
Hiroyuki Takao ◽  
Soichiro Fujimura ◽  
Chihebeddine Dahmani ◽  
Toshihiro Ishibashi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Reduction Rate ◽  
Flow Diverter ◽  
Outer Diameter ◽  
Cfd Simulations ◽  
Flow Reduction ◽  
Radial Stiffness ◽  
Flow Diverter Stent ◽  
Hemodynamic Performance ◽  
Longitudinal Flexibility

BackgroundAlthough flow diversion is a promising procedure for the treatment of aneurysms, complications have been reported and it remains poorly understood. The occurrence of adverse outcomes is known to depend on both the mechanical properties and flow reduction effects of the flow diverter stent.ObjectiveTo clarify the possibility of designing a flow diverter stent considering both hemodynamic performance and mechanical properties.Materials and methodsComputational fluid dynamics (CFD) simulations were conducted based on an ideal aneurysm model with flow diverters. Structural analyses of two flow diverter models exhibiting similar flow reduction effects were performed, and the radial stiffness and longitudinal flexibility were compared.ResultsIn CFD simulations, two stents–Pore2-d35 (26.77° weave angle when fully expanded, 35 μm wire thickness) and Pore3-d50 (36.65°, 50 μm respectively)–demonstrated similar flow reduction rates (68.5% spatial-averaged velocity reduction rate, 85.0% area-averaged wall shear stress reduction rate for Pore2-d35, and 68.6%, 85.4%, respectively, for Pore3-d50). However, Pore3-d50 exhibited greater radial stiffness than Pore2-d35 (40.0 vs 21.0 mN/m at a 3.5 mm outer diameter) and less longitudinal flexibility (0.903 vs 0.104 N·mm bending moments at 90°). These measurements indicate that changing the wire thickness and weave angle allows adjustment of the mechanical properties while maintaining the same degree of flow reduction effects.ConclusionsThe combination of CFD and structural analysis can provide promising solutions for an optimized stent. Stents exhibiting different mechanical properties but the same flow reduction effects could be designed by varying both the weave angle and wire thickness.

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.

scholarly journals The FRED Flow-Diverter Stent for Intracranial Aneurysms: Clinical Study to Assess Safety and Efficacy

2015 ◽  
Vol 36 (6) ◽  
pp. 1155-1161 ◽  
Author(s):  
M.A. Möhlenbruch ◽  
C. Herweh ◽  
L. Jestaedt ◽  
S. Stampfl ◽  
S. Schönenberger ◽  
...  
Keyword(s):  
Clinical Study ◽  
Intracranial Aneurysms ◽  
Flow Diverter ◽  
Safety And Efficacy ◽  
Flow Diverter Stent

scholarly journals Flow-Diverter Stent for the Endovascular Treatment of Intracranial Aneurysms

Stroke ◽  
2010 ◽  
Vol 41 (10) ◽  
pp. 2247-2253 ◽  
Author(s):  
Boris Lubicz ◽  
Laurent Collignon ◽  
Gaï Raphaeli ◽  
Jean-Pierre Pruvo ◽  
Michaël Bruneau ◽  
...  
Keyword(s):  
Endovascular Treatment ◽  
Intracranial Aneurysms ◽  
Flow Diverter ◽  
Flow Diverter Stent

scholarly journals Neurovascular reconstruction with flow diverter stents for the treatment of 87 intracranial aneurysms: Clinical results

2015 ◽  
Vol 21 (3) ◽  
pp. 292-299 ◽  
Author(s):  
Leonardo Giacomini ◽  
Ronie L Piske ◽  
Carlos E Baccin ◽  
Marcelo Barroso ◽  
Andrei F Joaquim ◽  
...  
Keyword(s):  
Intracranial Aneurysms ◽  
Interventional Neuroradiology ◽  
Clinical Results ◽  
Flow Diverter ◽  
High Rate ◽  
Complex Aneurysms ◽  
Results Of Treatment ◽  
Silk Stent ◽  
Flow Diverter Stent ◽  
Aneurysm Occlusion

Background Flow diverter stents represent a new endovascular tool to treat complex aneurysms, such as giant, large, wide-necked and fusiform. The highly dense mash of these stents reduces inflow and outflow inside the aneurysm, resulting in intra aneurysmal thrombosis and stent endothelialization. Objectives To present the results of treatment of intracranial aneurysms with flow diverter stents in a single center. Methods Retrospective review of 77 patients with 87 aneurysms treated using two different types of flow diverter stent, the Pipeline Embolization Device and SILK stent, between October 2010 and September 2013 in an interventional neuroradiology center. Results Flow diverter stent placement was successful in 98% of the lesions and resulted in an immediate major stasis within most of the treated aneurysms. The overall aneurysm occlusion rate at six months and 18 months was 80% and 84% respectively. Symptomatic complications occurred in 11 patients (14.3%) with morbidity in eight (10.4%) and mortality in three patients (3.9%). Conclusion Flow diversion is a promising technique for treatment of challenging intracranial aneurysms with acceptable morbidity. A high rate of complete occlusion for small large necked aneurysms, a low morbidity and mortality rate and no recanalization encourage their use in these aneurysms. Further studies accessing long-term aneurysm occlusion and recanalization are required.

Optimization of Strut Placement in Flow Diverter Stents for Four Different Aneurysm Configurations

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Hitomi Anzai ◽  
Jean-Luc Falcone ◽  
Bastien Chopard ◽  
Toshiyuki Hayase ◽  
Makoto Ohta
Keyword(s):  
Arterial Occlusion ◽  
Flow Simulation ◽  
Flow Diverter ◽  
Optimal Placement ◽  
Parent Artery ◽  
High Porosity ◽  
Mesh Structure ◽  
Flow Reduction ◽  
Fine Mesh ◽  
Flow Diverter Stent

A modern technique for the treatment of cerebral aneurysms involves insertion of a flow diverter stent. Flow stagnation, produced by the fine mesh structure of the diverter, is thought to promote blood clotting in an aneurysm. However, apart from its effect on flow reduction, the insertion of the metal device poses the risk of occlusion of a parent artery. One strategy for avoiding the risk of arterial occlusion is the use of a device with a higher porosity. To aid the development of optimal stents in the view point of flow reduction maintaining a high porosity, we used lattice Boltzmann flow simulations and simulated annealing optimization to investigate the optimal placement of stent struts. We constructed four idealized aneurysm geometries that resulted in four different inflow characteristics and employed a stent model with 36 unconnected struts corresponding to the porosity of 80%. Assuming intracranial flow, steady flow simulation with Reynolds number of 200 was applied for each aneurysm. Optimization of strut position was performed to minimize the average velocity in an aneurysm while maintaining the porosity. As the results of optimization, we obtained nonuniformed structure as optimized stent for each aneurysm geometry. And all optimized stents were characterized by denser struts in the inflow area. The variety of inflow patterns that resulted from differing aneurysm geometries led to unique strut placements for each aneurysm type.

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