Determination of a shear rate threshold for thrombus formation in intracranial aneurysms

Sousa, Daniel Ribeiro de; Vallecilla, Carolina; Chodzynski, Kamil; Corredor-Jerez, Ricardo; Malaspinas, Orestis; Eker, Omer; Ouared, Rafik; Vanhamme, Luc; Legrand, Alexandre; Chopard, Bastien; Courbebaisse, Guy; Boudjeltia, Karim Zouaoui

doi:10.1136/neurintsurg-2015-011737

Cited by 33 publications

(21 citation statements)

References 26 publications

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“…The main triggering mechanism that we propose is the production of thrombin by the endothelial cells exposed to a low wall shear stress. This hypothesis is confirmed by our in-vitro experiments, and clinical observation [8]. Note that the placement of a flow diverter, whose goal is precisely to cause embolization of the aneurysm cavity by a flow reduction, is also compatible with the hypothesis of a low WSS switch.…”

Section: Resultssupporting

confidence: 85%

“…8 and has a period of one second. The critical wall shear stress is given by w c = 0.0054Pa, which corresponds to a wall shear rate of 1.35s −1 , well in the range proposed in [8]. The fibrinogen and anti-thrombin being naturally present in blood, they are injected at the inlets of our simulations, at the rates Q AT and Q F given in Table 1.…”

Section: Validation On Two Patient Specific Casesmentioning

confidence: 82%

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A spatio-temporal model for spontaneous thrombus formation in cerebral aneurysms

Malaspinas

Turjman²,

Sousa³

et al. 2015

Preprint

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We propose a new numerical model to describe thrombus formation in cerebral aneurysms. This model combines CFD simulations with a set of bio-mechanical processes identified as being the most important to describe the phenomena at a large space and time scales. The hypotheses of the model are based on in vitro experiments and clinical observations. We document that we can reproduce very well the shape and volume of patient specific thrombus segmented in giant aneurysms. are co-directors of this work.

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Section: Resultssupporting

confidence: 85%

Section: Validation On Two Patient Specific Casesmentioning

confidence: 82%

A spatio-temporal model for spontaneous thrombus formation in cerebral aneurysms

Malaspinas

Turjman²,

Sousa³

et al. 2015

Preprint

Self Cite

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“…In each case the majority of the blood leaving the aneurysm appears to do so in the direction of the corresponding unstented daughter vessel. 28 The angle at which flow strikes the device mesh and the daughter vessel ostium, and hence the effective device porosity, appear similar for both device configurations. Thus, the relatively small 5.5% difference in Qin reduction seen between the Left and Right configurations may not be the result of porosity differences, but the different fractions of flow exiting via each daughter vessel alone.…”

Section: Aneurysm IImentioning

confidence: 93%

“…(25,26) But, such heuristics should be viewed cautiously with studies in the literature also suggesting that both spatial and temporal variations 6 in WSS distribution, including local jetting and harmonic frequencies, may also play a significant role in thrombus initiation and growth. (27)(28)(29) In this study, three Basilar artery bifurcation aneurysms are examined with CFD models, and the effects of different FD configurations on aneurysm inflow reduction and changes in mean and peak WSS are evaluated. Each aneurysm geometry was chosen to have relatively symmetric-sized daughter vessels (Posterior Cerebral Arteries), thus rendering the treatment decision of where to deploy a FD device non-obvious.…”

Section: Introductionmentioning

confidence: 99%

Virtual flow-diverter treatment planning: The effect of device placement on bifurcation aneurysm haemodynamics

Peach

Spranger

Ventikos

2016

Proc Inst Mech Eng H

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Bifurcation aneurysms account for a large fraction of cerebral aneurysms and often present morphologies that render traditional endovascular treatments, such as coiling, challenging and problematic. Flow-diverter stents offer a potentially elegant treatment option for such aneurysms, but clinical use of these devices remains controversial. Specifically, the deployment of a flow-diverter device in a bifurcation entails jailing one or more potentially vital vessels with a low-porosity mesh designed to restrict the flow. When multiple device placement configurations exist, the most appropriate clinical decision becomes increasingly opaque. In this study, three bifurcation aneurysm geometries were virtually treated by flow-diverter device. Each aneurysm was selected to offer two possible device deployment positions. Flow-diverters similar to commercially available designs were deployed with a fast-deployment algorithm before transient and steady state computational fluid dynamics simulations were performed. Reductions in aneurysm inflow, mean wall shear stress and maximum wall shear stress, all factors often linked with aneurysm treatment outcome, were compared for different device configurations in each aneurysm. In each of the three aneurysms modelled, a particular preferential device placement was shown to offer superior performance with the greatest reduction in the flow metrics considered. In all the three aneurysm geometries, substantial variations in inflow reduction (up to 25.3%), mean wall shear stress reduction (up to 14.6%) and maximum wall shear stress reduction (up to 12.1%) were seen, which were all attributed to device placement alone. Optimal device placement was found to be non-trivial and highly aneurysm specific; in only one-third of the simulated geometries, the best overall performance was achieved by deploying a device in the daughter vessel with the highest flow rate. Good correspondence was seen between transient results and steady state computations that offered a significant reduction in simulation run time. If accurate steady state computations are combined with the fast-deployment algorithm used, the modest run time and corresponding hardware make a virtual treatment pipeline in the clinical setting a meaningful possibility.

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“…In this method, platelets are modelled as point particles tracing flow lines as passive scalars [22], which was able to reproduce the shape and volume of formed thrombi in patient-specific aneurysms [23]. This method also revealed through a cross-sectional study of 21 patients an association between spontaneous thrombosis and aneurysm dome to neck aspect ratio [24].…”

Section: Introductionmentioning

confidence: 99%

Cell-resolved blood flow simulations of saccular aneurysms: effects of pulsatility and aspect ratio

Czaja

Závodszky

Tarksalooyeh

et al. 2018

J. R. Soc. Interface.

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We study the effect of pulsatile flow on the transport of red blood cells (RBCs) and platelets into aneurysm geometries with varying dome-to-neck aspect ratios (AR). We use a validated two-dimensional lattice Boltzmann model for blood plasma with a discrete element method for both RBCs and platelets coupled by the immersed boundary method. Flow velocities and vessel diameters were matched with measurements of cerebral perforating arteries and flow was driven by a synthetic heartbeat curve typical for such vessel sizes. We observe a flow regime change as the aspect ratio increases from a momentum-driven regime in the small aspect ratio to a shear-driven regime in the larger aspect ratios. In the small aspect ratio case, we see the development of a re-circulation zone that exhibits a layering of high (greater than or equal to 7 s) and low (less than 7 s) residence cells. In the shear-driven regime, we see high and low residence cells well mixed, with an increasing population of cells that are trapped inside the aneurysm as the aspect ratio increases. In all cases, we observe aneurysms that are platelet-rich and red blood cell-poor when compared with their respective parental vessel populations. Pulsatility also plays a role in the small aspect ratio as we observe a smaller population of older trapped cells along the aneurysm wall in the pulsatile case when compared with a steady flow case. Pulsatility does not have a significant effect in shear-driven regime aspect ratios.

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Determination of a shear rate threshold for thrombus formation in intracranial aneurysms

Cited by 33 publications

References 26 publications

A spatio-temporal model for spontaneous thrombus formation in cerebral aneurysms

A spatio-temporal model for spontaneous thrombus formation in cerebral aneurysms

Virtual flow-diverter treatment planning: The effect of device placement on bifurcation aneurysm haemodynamics

Cell-resolved blood flow simulations of saccular aneurysms: effects of pulsatility and aspect ratio

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