In vitro hydrodynamical study on aneurysmal morphology for treating intracranial aneurysms using particle imaging velocimetry

Moriwaki, Takeshi; Tajikawa, Tsutomu; Nakayama, Yasuhide

doi:10.17106/jbr.34.47

Cited by 3 publications

(16 citation statements)

References 23 publications

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“…These observations differ from those of Moriwaki et al. (2020), where for all geometries the flow remained attached after treatment with FDS. This difference can be due to the fact that they performed the experiments with steady inflow and that the aneurysms were on straight vessels.…”

Section: Flow After Treatment With Fdscontrasting

confidence: 99%

“…Similarly, Moriwaki et al. (2020) and Asgharzadeh & Borazjani (2019) observed lower velocities for low aspect ratios. However, the volume of the sac was not constant throughout their experiments, making the comparison between the different aspect ratios inconclusive.…”

Section: Resultsmentioning

confidence: 72%

“…In their experimental study with steady inflow in the parent vessel, Moriwaki et al. (2020) also observed an increase in the velocity in the sac as the neck size increased.

Figure 5.Time-averaged circulation in the sac, , as a function of for all curvatures and neck sizes for high ( a ) and low ( b ) .…”

Section: Resultsmentioning

confidence: 91%

“…Moriwaki et al. (2020) performed PIV measurements with steady inflow, in sac geometries similar to ours, but attached to straight vessels. For low aspect ratios, they also observed a large area of very low velocity at the tip of the aneurysmal sac.…”

Section: Resultsmentioning

confidence: 94%

“…2018; Moriwaki et al. 2020). The FDS also induced a strong modification of the intra-aneurysmal flow patterns, dependent on geometry.…”

Section: Flow After Treatment With Fdsmentioning

confidence: 99%

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Fluid dynamics in intracranial aneurysms treated with flow-diverting stents: effect of multiple geometrical parameters

Chassagne,

Barbour,

Levitt

et al. 2023

J. Fluid Mech.

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Characterizing the haemodynamics in intracranial aneurysms is of high interest as it impacts aneurysm growth, rupture and treatment, especially with flow-diverting stents (FDS). Flow in these geometries is known to depend on the Dean, Reynolds and Womersley numbers, $De$ , $Re$ , $Wo$ , but is also influenced by geometrical parameters such as the sac shape or the size of the opening. Via particle image velocimetry, this parametric study aimed at evaluating the combined effects of $Re$ , $De$ , $Wo$ and the geometry of the aneurysmal sac on the haemodynamics before and after treatment with FDS. Eight ellipsoidal idealized aneurysm models were created with two curvatures of the parent vessel, two aspect ratios of the sac and two neck sizes. Before treatment, a single counter-rotating vortex, whose strength increases with $Re$ and $De$ , as well as with the neck size and the aspect ratio, was observed in the sac for all but one geometry. After treatment with FDS, four different flow topologies were observed, depending on the geometry: no separation, separation for part of the cycle, two opposing vortices or a single counter-rotating vortex. A linear model with interaction revealed the predominant effect of $De$ and the curvature of the parent vessel on the haemodynamics before and after treatment. This work once more demonstrated the primary role of haemodynamics in the treatment of intracranial aneurysms with FDS. Future work will consider the complexity of patient-specific geometries, and their effects on both the haemodynamics in the sac and the porosity of the FDS.

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Section: Flow After Treatment With Fdscontrasting

confidence: 99%

Section: Resultsmentioning

confidence: 72%

“…In their experimental study with steady inflow in the parent vessel, Moriwaki et al. (2020) also observed an increase in the velocity in the sac as the neck size increased.

Figure 5.Time-averaged circulation in the sac, , as a function of for all curvatures and neck sizes for high ( a ) and low ( b ) .…”

Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 94%

“…2018; Moriwaki et al. 2020). The FDS also induced a strong modification of the intra-aneurysmal flow patterns, dependent on geometry.…”

Section: Flow After Treatment With Fdsmentioning

confidence: 99%

See 3 more Smart Citations

Fluid dynamics in intracranial aneurysms treated with flow-diverting stents: effect of multiple geometrical parameters

Chassagne,

Barbour,

Levitt

et al. 2023

J. Fluid Mech.

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Model blood for simulating red thrombus formation owing to stagnant blood flow using hypercoagulable skim milk solution

TAJIKAWA,

HIRONO,

TANAKA

et al. 2024

JBSE

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The thrombus formation process has yet to be fully simulated, which necessitates the design of a novel method for the quantitative assessment of device thrombogenicity that complements animal experiments/ex vivo experiments using animal blood and computational fluid dynamics analysis. This study aimed to develop a model blood capable of simulating the formation of red thrombus owing to stagnation of blood flow by applying the phenomenon of milk clot formation. To render the rheological properties of skim milk solution used as a model blood closer to those of human blood, the ratio of the amounts of casein in skim milk, calcium chloride, and rennet (constituents of the solution of the model blood) was varied and the rheological properties of the clot formation process of human blood and skim milk solution were measured using a cone-plate viscometer. Comparisons of the rheological properties of human blood and skim milk solutions during clotting revealed that during clot formation of human blood, four characteristic quantities of the time-series change in rheological properties were observed: the viscosity before clotting, coagulation start time, viscosity increase rate, and first yield viscosity. Further, hypercoagulable skim milk solutions with rheological properties similar to those of human blood were prepared by adjusting the solution composition ratio. When this model blood was circulated in a closed-loop circuit with a saccular aneurysm model, the growth rate of skim milk clot formation in the aneurysm model was significantly different in a flow diverter stent model and a micro-porous covered stent. The variation in porosity between these two stent models has a direct impact on the rate of embolisation. The proposed blood model can effectively replicate the formation of red thrombus, providing a valuable means to accurately and quantitatively assess the therapeutic efficacy of embolisation devices.

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<i>In vitro</i> hydrodynamical study on parent vessel curvature for treating intracranial aneurysms using particle imaging velocimetry

Tajikawa,

Hidaka,

Moriwaki

et al. 2023

J Biorheol

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We have developed a micro-porous covered stent (NCVC-CS1) for intracranial aneurysm (IA) treatment. Thrombus formation is locally promoted by flow diversion or isolation in the target IA after stenting, and the IA can be embolised. Despite using the same stent in clinical practice, the therapeutic effect may not be the same because the size and morphology of the IA and the parent vessel flow affect IA flow. Therefore, this study clarifies the influence of flow in a curved parent vessel on the flow diversion/isolation performance of the low-porosity stent using particle imaging velocimetry (PIV). In vitro experiments were conducted under steady flow conditions based on a flow similarity law using a two-dimensional parent vessel model with a saccular IA, a U-shaped parent vessel, and a simplified micro-porous film model. The results indicated that the area mean shear rate was well expressed by a power function using the Dean number. The cross-flow velocity component's root mean square (RMS) perpendicular to the IA neck increased with a sharply curved vessel. In particular, when the curvature-radius ratio was larger than 1/2, the RMS of the cross-flow velocity remarkably increased despite stenting, suggesting that the stenting performance in a sharper-curved vessel is significantly affected.

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In vitro hydrodynamical study on aneurysmal morphology for treating intracranial aneurysms using particle imaging velocimetry

Cited by 3 publications

References 23 publications

Fluid dynamics in intracranial aneurysms treated with flow-diverting stents: effect of multiple geometrical parameters

Fluid dynamics in intracranial aneurysms treated with flow-diverting stents: effect of multiple geometrical parameters

Model blood for simulating red thrombus formation owing to stagnant blood flow using hypercoagulable skim milk solution

<i>In vitro</i> hydrodynamical study on parent vessel curvature for treating intracranial aneurysms using particle imaging velocimetry

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