Does the gravity orientation of saccular aneurysms influence hemodynamics? An experimental study with and without flow diverter stent

Chodzynski, Kamil; Vanrossomme, Axel; Sousa, Daniel Ribeiro de; Coussement, Grégory; Vanhamme, Luc; Dubois, Frank; Bonafé, Alain; Chopard, Bastien; Courbebaisse, Guy; Boudjeltia, Karim Zouaoui

doi:10.1016/j.jbiomech.2016.10.007

Cited by 6 publications

(11 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Final haematocrits, reported in table 1, are significantly lower than the parental vessel haematocrits. Flow of cells into these geometries is qualitatively similar to observations made in in vitro experiments of spherical sidewall aneurysms [49].…”

Section: Empty Initializationsupporting

confidence: 76%

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

Czaja

Závodszky

Tarksalooyeh

et al. 2018

J. R. Soc. Interface.

View full text Add to dashboard Cite

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.

show abstract

Section: Empty Initializationsupporting

confidence: 76%

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

Czaja

Závodszky

Tarksalooyeh

et al. 2018

J. R. Soc. Interface.

View full text Add to dashboard Cite

show abstract

“…This study focused on the ability of the injected sample to fill the cavity and the duration of its washout, mimicking the results obtained with digital subtractive angiography in vivo 25 . www.nature.com/scientificreports www.nature.com/scientificreports/ The optical technique used here was based on the imaging of coloured markers, namely red dye (1 nm diameter) and RBCs (6-8 µm diameter) 26 . Because it is technically difficult to detect markers inside full blood due to its opacity, we tracked markers in the transparent liquid part of blood.…”

Section: Discussionmentioning

confidence: 99%

“…Current methods to study the flow diverter impact over aneurysms included in vivo experimentation in animals 16,18 , in vitro experiments using silicone models 15,22,26 and CFD simulations 7,11,13,20 . In vivo approaches give physiological information on the flow diverter effect such as blood flow alteration, vessel geometry or clot formation in long time range 16,18,25 .…”

Section: Discussionmentioning

confidence: 99%

“…These two markers have different light absorbances, altering the detection of their distribution within the silicone model. The effect of gravity on the RBCs may also play a role 26 . The difference may also be related to the size of the red dye and RBC particles and to the higher energy dissipation of the RBCs on the flow diverter wires because of their larger size.…”

Section: Discussionmentioning

confidence: 99%

“…In vitro test bench settings. The full procedure has been described in previous work by Chodzyński et al 26 .…”

Section: Discussionmentioning

confidence: 99%

See 2 more Smart Citations

The impact of arterial flow complexity on flow diverter outcomes in aneurysms

Chodzynski

Uzureau

Nuyens

et al. 2020

Sci Rep

Self Cite

View full text Add to dashboard Cite

The flow diverter is becoming a standard device for treating cerebral aneurysms. The aim of this in vitro study was to evaluate the impact of flow complexity on the effectiveness of flow diverter stents in a cerebral aneurysm model. The flow pattern of a carotid artery was decomposed into harmonics to generate four flow patterns with different pulsatility indexes ranging from 0.72 to 1.44. The effect of flow diverters on the aneurysm was investigated by injecting red dye or erythrocytes as markers. The recorded images were postprocessed to evaluate the maximum filling of the aneurysm cavity and the washout time. There were significant differences in the cutoff flows between the markers, linked to the flow complexity. Increasing the pulsatility index altered the performance of the flow diverter. The red dye was more sensitive to changes in flow than the red blood cell markers. The flow cutoff depended on the diverter design and the diverter deployment step was crucial for reproducibility of the results. These results strongly suggest that flow complexity should be considered when selecting a flow diverter. Flow diverters are common devices for treating large or complex intracranial aneurysms. As the mechanisms underlying aneurysm occlusion are still not fully understood, the choice of flow diverter is mainly empirical and based on the physician's own experience 1,2. Outcomes range from complete or partial occlusion after varying periods to lack of thrombosis or even haemorrhage 3,4. The factors responsible for occlusion following flow diverter placement are still under debate 3,5. Analysis of the flow inside large aneurysms reveals that, by contrast with small aneurysms where flow is similar to the parent vessel, the flow pattern can be markedly altered 6. Recent studies show that flow complexity is a key factor in flow diverter performance. Computational fluid dynamics (CFD) simulations showed that flow reduction following flow diverter treatment was more noticeable during diastole than systole and that flow diverter performance was related to the flow pattern 7,8. Although blood flow complexity can be fully described using a Fourier decomposition into harmonics, these values are not commonly used in the medical field 9. Instead, the pulsatility index, which can be directly assessed from Doppler or magnetic resonance imaging (MRI) examinations, is more widely used to describe the complexity of patient blood flows 10. The pulsatility index varies within the cerebral arterial tree and within the same artery in different patients, reflecting the diversity of flow patterns that can be encountered within the vessels altered by aneurysms 11,12. Different outcomes are therefore observed when the same flow diverter is used in situations of different flow patterns associated with vessel geometry and position in the cerebral arterial tree, and the physiological state and activity of the patient 13,14. In addition, flow diverter design, including the number of layers, porosity, number of holes, weave angle, wire diameter, a...

show abstract

Experimental and numerical study of the effect of pulsatile flow on wall displacement oscillation in a flexible lateral aneurysm model

et al. 2019

Acta Mech. Sin.

View full text Add to dashboard Cite

Does the gravity orientation of saccular aneurysms influence hemodynamics? An experimental study with and without flow diverter stent

Cited by 6 publications

References 16 publications

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

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

The impact of arterial flow complexity on flow diverter outcomes in aneurysms

Experimental and numerical study of the effect of pulsatile flow on wall displacement oscillation in a flexible lateral aneurysm model

Contact Info

Product

Resources

About