PIV investigation of the flow fields in subject-specific vertebro-basilar (VA-BA) junction

Abstract

Background As the only arterial structure of which two main arteries merged into one, the vertebro-basilar (VA-BA) system is one of the favorite sites of cerebral atherosclerotic plaques. The aim of this study was to investigate the detailed hemodynamics characteristics in the VA-BA system. Methods A scale-up subject-specific flow phantom of VA-BA system was fabricated based on the computed tomography angiography (CTA) scanning images of a healthy adult. Flow fields in eight axial planes and six radial planes were measured and analyzed by using particle image velocimetry (PIV) under steady flow conditions of , . A water–glycerin mixture was used as the working fluid. Results The flow in the current model exhibited highly three-dimensional characteristics. The confluence of VAs flow formed bimodal velocity distribution near the confluence apex. Due to the asymmetrical structural configuration, the bimodal velocity profile skewed towards left, and sharper peaks were observed under higher Reynolds condition. Secondary flow characterized by two vortices formed in the radial planes where 10 mm downstream the confluence apex and persists along the BA under both Reynolds numbers. The strength of secondary flow under is around 8% higher than that under , and decayed nonlinearly along the flow direction. In addition, a low momentum recirculation region induced by boundary layer separation was observed near the confluence apex. The wall shear stress (WSS) in the recirculation area was found to be lower than 0.4 Pa. This region coincides well with the preferential site of vascular lesions in the VA-BA system. Conclusions This preliminary study verified that the subject-specific in-vitro experiment is capable of reflecting the detailed flow features in the VA-BA system. The findings from this study may help to expand the understanding of the hemodynamics in the VA-BA system, and further clarifying the mechanism that underlying the localization of vascular lesions.

Collateral flow at circle of Willis in healthy condition

“…6 Blood flow through ACoA and PCoAs under complete CAC can be related to cerebral autoregulation which brain cells receive glaucose and nutrient at the different lobe sites at the same time that mentioned the hemostasis concept. [17][18][19] The great metabolic plea of neuronal tissue needs enclosed coordination between neuronal activity and blood flow within the brain parenchyma. To maintain neuronal performance, the cerebro-tissue has developed 'neurovascular coupling' pattern to ascend the flow of blood to regions in which neurons are active and by this mechanism cerebral blood flow autoregulation system maintain adequate blood flow to each lobe.…”

Experimental validation of computational fluid dynamics for solving isothermal and incompressible viscous fluid flow

“…Herein, we present an experimental study on an eccentric cylindrical cavity, in which the flow is studied by means of particle image velocimetry (PIV) [25]. This standard technique is often employed for laminar flows [26][27][28], in order to study the transient response [29], or behind an obstacle [30,31]. In this work, fluorescent particles are used both for flow visualization (FV) and PIV at the central plane of a symmetric flow cavity.…”