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"... Study of parameters for evaluating flow reduction with stents in a sidewall aneurysm ..."
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Study of parameters for evaluating flow reduction with stents in a sidewall aneurysm
CINEMATIC ANGIOGRAPHY FOR MEASUREMENTS OF BLOOD FLOW IN CEREBRAL ANEURYSMS WITH STENTS
"... ABSTRACT Background and Purpose: The assessment of blood flow speed by imaging modalities is important for endovascular treatments, such as stent implantation, of cerebral aneurysms. The subtracted vortex centers path line method (SVC method) is one of the ways of determining flow speed quantitativ ..."
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ABSTRACT Background and Purpose: The assessment of blood flow speed by imaging modalities is important for endovascular treatments, such as stent implantation, of cerebral aneurysms. The subtracted vortex centers path line method (SVC method) is one of the ways of determining flow speed quantitatively using the image sequence. And a cinematic angiography (CA) is a high speed image acquisition system using X-ray and contrast media integrated in Digital Subtraction Angiography (DSA) for endovascular therapy. The combination of SVC and CA may useful for determining the blood flow speed during the operation using DSA. In this study, we applied this combination to analyze hemodynamic changes before and after stenting. Methods: A transparent tubular model was constructed of silicone which included an aneurysm 10 mm in diameter and having a 5 mm neck on a straight parent artery with a diameter of 3.5 mm. The model was integrated into a pulsatile circulation system. A double layer stent was placed in the parent artery on the aneurysm. By CA, successive images at 25 frames per second with injection of contrast were obtained. Results and conclusion: Rotating vortexes of contrast, which advanced along the wall of the aneurysm, were observed in successive images of the aneurysm cavity. The movement distance of the vortex center was measured and the results show that the vortex speed decrease after stenting. This indicates the possibility of applying the SVC method to medical imaging equipment for analysis of the flow in aneurysms containing stent.
Finite Element Modeling of the Hemodynamics . . .
"... Background. Computational fluid dynamics (CFD) simulations are used to analyze the wall shear stress distribution and flow streamlines near the throat of a stented basilar side-wall aneurysm. Previous studies of stented aneurysm flows used low mesh resolution, did not include mesh convergence analys ..."
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Background. Computational fluid dynamics (CFD) simulations are used to analyze the wall shear stress distribution and flow streamlines near the throat of a stented basilar side-wall aneurysm. Previous studies of stented aneurysm flows used low mesh resolution, did not include mesh convergence analyses, and depended upon conformal meshing techniques that apply only to very artificial stent geometries.
Simulation of Intra-Aneurysmal Blood Flow by using Different Numerical Methods
"... The occlusional performance of sole endoluminal stenting of intracranial aneurysms is controversially discussed in the literature. Simulation of blood flow has been studied to shed light on possible causal attributions. The out-come however, largely depends on various free parameters which all could ..."
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The occlusional performance of sole endoluminal stenting of intracranial aneurysms is controversially discussed in the literature. Simulation of blood flow has been studied to shed light on possible causal attributions. The out-come however, largely depends on various free parameters which all could have considerable impact on simulation results. The choice of a numeri-cal method could be seen as the first free parameter. The present study is therefore conducted to find ways to define parameters and efficiently explore ∗Corresponding author
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"... 2Abstract Occlusional performance of sole endoluminal stenting of intracra-nial aneurysms is controversially discussed in literature. Simulation of blood flow have been studied to shed light on possible causal attributions. The out-come however largely depends on the degree of accuracy of geometry r ..."
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2Abstract Occlusional performance of sole endoluminal stenting of intracra-nial aneurysms is controversially discussed in literature. Simulation of blood flow have been studied to shed light on possible causal attributions. The out-come however largely depends on the degree of accuracy of geometry repre-sentation as provided by the means of segmentation. The current study was therefore conducted to learn more about the impact of segmentation artifacts on the results of Computational Fluid Dynamics (CFD). The 2D architec-ture of the intracranial aneurysm was based on histology. CFD was applied to assess flow and aneurysmal vorticity. As expected, the quality of the input determines the quality of the output. Stent design alone can diminish or at least has considerable influence on blood flow into the lesion. The amount of inaccuracy that is acceptable may correlate with the size of the database and properties of its application.
Research Article Y-Stenting for Bifurcation Aneurysm Coil Embolization: What is the Risk?
"... Copyright © 2014 Alejandro M. Spiotta et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The use of two stents in a “Y ” configur ..."
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Copyright © 2014 Alejandro M. Spiotta et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The use of two stents in a “Y ” configuration (Y-stenting) to assist with coil embolization of complex bifurcation aneurysms has been accepted as an alternative to clip reconstruction of a select subset of challenging aneurysms. We review the risks associated with Y-stenting, including its procedural complication rates, angiographic occlusion rates, rerupture, and retreatment rates. 1.
CLASSIFICATION OF BLOOD FLOW IN CEREBRAL ANEURYSM CONSIDERING THE PARENT ARTERY CURVES
"... Background and purpose: Recently, the number of endovascular treatments has increased worldwide because of advances in minimally invasive surgery. We considered the effect of reduced flow due to stent implantation and proposed the design of stent strut pattern from the viewpoint of fluid dynamics. W ..."
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Background and purpose: Recently, the number of endovascular treatments has increased worldwide because of advances in minimally invasive surgery. We considered the effect of reduced flow due to stent implantation and proposed the design of stent strut pattern from the viewpoint of fluid dynamics. We developed an optimized stent strut pattern using a computational fluid dynamics (CFD) system. A classification of cerebral aneurysms was proposed using the aspect ratio (AR) and the stent strut pattern was optimized. The results of optimal stent strut pattern for reduced blood flow speed and wall shear stress were different, and the influence of the AR values was small because there was no dependence on relationship between blood flow and the AR values due to the use of a straight pipe in the parent artery. The classification of blood
Research Article Simulation of Intra-Aneurysmal Blood Flow by Different Numerical Methods
"... Copyright © 2013 Frank Weichert et al.This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The occlusional performance of sole endoluminal ..."
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Copyright © 2013 Frank Weichert et al.This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The occlusional performance of sole endoluminal stenting of intracranial aneurysms is controversially discussed in the literature. Simulation of blood flow has been studied to shed light on possible causal attributions. The outcome, however, largely depends on the numerical method and various free parameters.The present study is therefore conducted to find ways to define parameters and efficiently explore the huge parameter space with finite element methods (FEMs) and lattice Boltzmannmethods (LBMs).The goal is to identify both the impact of different parameters on the results of computational fluid dynamics (CFD) and their advantages and disadvantages. CFD is applied to assess flow and aneurysmal vorticity in 2D and 3D models. To assess and compare initial simulation results, simplified 2D and 3Dmodels based on key features of real geometries andmedical expert knowledge were used. A result obtained from this analysis indicates that a combined use of the different numerical methods, LBM for fast exploration and FEM for a more in-depth look, may result in a better understanding of blood flow and may also lead to more accurate information
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"... Downloaded Fpacking agents such as balloon and/or platinum microcoils are likely to extent or migrate from the aneurysm into the parent vessel, an alternative approach is intravascular stenting ..."
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Downloaded Fpacking agents such as balloon and/or platinum microcoils are likely to extent or migrate from the aneurysm into the parent vessel, an alternative approach is intravascular stenting
