Rest versus Exercise Hemodynamics for Middle Cerebral Artery Aneurysms: A Computational Study

Bowker, Timothy J.; Watton, Paul N.; Summers, Paul; Byrne, James; Ventikos, Yiannis

doi:10.3174/ajnr.a1797

Cited by 28 publications

(22 citation statements)

References 31 publications

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“…This parameter identifies regions of stagnation in the flow. The magnitudes we observed are consistent with those for physiological aneurysms with wide necks (Bowker et al 2010), i.e. up to 1,000.…”

Section: Discussionsupporting

confidence: 92%

Modelling evolution and the evolving mechanical environment of saccular cerebral aneurysms

Watton

Selimovic

Raberger

et al. 2010

Biomech Model Mechanobiol

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A fluid-solid-growth (FSG) model of saccular cerebral aneurysm evolution is developed. It utilises a realistic two-layered structural model of the internal carotid artery and explicitly accounts for the degradation of the elastinous constituents and growth and remodelling (G&R) of the collagen fabric. Aneurysm inception is prescribed: a localised degradation of elastin results in a perturbation in the arterial geometry; the collagen fabric adapts, and the artery achieves a new homeostatic configuration. The perturbation to the geometry creates an altered haemodynamic environment. Subsequent degradation of elastin is explicitly linked to low wall shear stress (WSS) in a confined region of the arterial domain. A sidewall saccular aneurysm develops, the collagen fabric adapts and the aneurysm stabilises in size. A quasi-static analysis is performed to determine the geometry at diastolic pressure. This enables the cyclic stretching of the tissue to be quantified, and we propose a novel index to quantify the degree of biaxial stretching of the tissue. Whilst growth is linked to low WSS from a steady (systolic) flow analysis, a pulsatile flow analysis is performed to compare steady and pulsatile flow parameters during evolution. This model illustrates the evolving mechanical environment for an idealised saccular cerebral aneurysm developing on a cylindrical parent artery and provides the guidance to more sophisticated FSG models of aneurysm evolution which link G&R to the local mechanical stimuli of vascular cells.

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Section: Discussionsupporting

confidence: 92%

Modelling evolution and the evolving mechanical environment of saccular cerebral aneurysms

Watton

Selimovic

Raberger

et al. 2010

Biomech Model Mechanobiol

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“…To this end, we conducted a study comparing simulations with 3DRA-and CTA-based vascular models of 10 aneurysms. Although relatively large discrepancies-exceeding normal physiologic variation 35 -were found between 3DRA and CTA models for quantitative hemodynamic variables, the visual categorization of flow characteristics was mostly reproduced across modalities and observers.…”

Section: Discussionmentioning

confidence: 99%

“…Other studies evaluated the intra-aneurysmal hemodynamics during rest and exercise conditions, which essentially combined the change in waveform shape, flow rate, and heart rate. Bowker et al 35 found that the overall flow patterns did not significantly change with a heart rate increase from 70 to 121 beats per minute and a flow-rate increase of 8%. However, Jiang and Strother 40 increased the heart rate from 60 to 150 beats per minute and the flow rate 21% and reported that the overall flow patterns did change significantly.…”

Section: Discussionmentioning

confidence: 99%

“…27,35,[38][39][40] Hoi et al 41 found differences in ICA and VA waveform shapes between young and older adults but concluded on the basis of a CFD study 39 of the carotid bifurcation that the computed hemodynamics are relatively robust to the assumed waveform shape in comparison with assumptions made on the timeaveraged flow rate, and especially in comparison with geometry-related uncertainties. Venugopal et al 38 similarly stressed the relative importance of the assumed flow rate and the outflow ratios in comparison with the assumed heart rate.…”

Section: Discussionmentioning

confidence: 99%

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Patient-Specific Computational Hemodynamics of Intracranial Aneurysms from 3D Rotational Angiography and CT Angiography: An In Vivo Reproducibility Study

Geers¹,

Larrabide²,

Radaelli³

et al. 2010

AJNR Am J Neuroradiol

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“…Transcranial Doppler has been used as an application of computational fluid dynamics because it can provide a detailed pulse wave form and blood flow velocity for each heart beat 20) . Although the pulse wave form and flow velocity can differ among individuals, there have been very few studies using patient-specific flow data 21) .…”

Section: Conflicts Of Interestmentioning

confidence: 99%

Geometric Analysis and Blood Flow Simulation of Basilar Artery

Lee

Hur

Jeong

2012

JAT

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Aim:The aim of this study was to find a region of low wall shear stress (WSS) in a basilar artery using 3-dimensional (3D) geometric analysis and blood flow simulation. Methods: A 61-year-old patient who underwent follow-up time-of-flight magnetic resonance angiography (TOF-MRA) of the brain was recruited as the subject of the present study. In the basilar artery, the angle of the directional vector was calculated for the region of low WSS. The subject's 3D arterial geometry and blood flow velocity from a transcranial Doppler examination were used for a blood flow simulation study. The regions of low WSS identified by both geometric analysis and blood flow simulation were compared, and these methods were repeated for the basilar arteries of various geometries from other patients.

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Rest versus Exercise Hemodynamics for Middle Cerebral Artery Aneurysms: A Computational Study

Cited by 28 publications

References 31 publications

Modelling evolution and the evolving mechanical environment of saccular cerebral aneurysms

Modelling evolution and the evolving mechanical environment of saccular cerebral aneurysms

Patient-Specific Computational Hemodynamics of Intracranial Aneurysms from 3D Rotational Angiography and CT Angiography: An In Vivo Reproducibility Study

Geometric Analysis and Blood Flow Simulation of Basilar Artery

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