Blood flow and macromolecular transport in complex blood vessels

Hong, Jinxing; Lan, Wei; Fu, Ceji; Tan, Wenchang

doi:10.1016/j.clinbiomech.2007.07.006

Cited by 15 publications

(10 citation statements)

References 16 publications

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“…2. Under the pulsatile flow condition, the peak Reynolds number was 350, and the lowest Reynolds number was 150. Outlet: At the outlet, the outflow boundary condition was set, that is, the flow at the outlet was set as a fully developed flow (25). The stent and the vessel wall were assumed to be rigid and nonslip.…”

Section: Methodsmentioning

confidence: 99%

A New Way to Reduce Flow Disturbance in Endovascular Stents: A Numerical Study

et al. 2011

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Traditional commercial stents are made of wires with square or semi-circular cross-sections that lead to flow disturbance, which plays an important role in the initiation and progression of restenosis. A new stent with streamlined cross-sectional wires was proposed and researched numerically for its hemodynamic performance. Simplified models of stents with square, semi-circular, or streamlined cross-sectional wires were constructed numerically. Blood flows in the three models were simulated using computational fluid dynamics methods, and compared in terms of flow pattern, wall shear stress (WSS), and oscillating shear index (OSI). The results showed that when compared with the two traditional stents, the new stent with streamlined cross-sectional wires induced almost no flow disturbance, significantly enhanced WSS, and reduced the value of OSI within the stent. The present preliminary study indicates that the optimization of the cross-sectional shape of stent wires ought to be considered in the structural design for endovascular stents.

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Section: Methodsmentioning

confidence: 99%

A New Way to Reduce Flow Disturbance in Endovascular Stents: A Numerical Study

et al. 2011

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“…Lipoprotein concentration polarization and flow field changes appear to lead to the alteration of atherogenic lipid transportation across the arterial luminal surface, causing vascular diseases such as lipoprotein deposition, blood platelet accumulation and intima thickening. Previous in vitro studies have shown that LDL concentration polarization exists in the vascular system [17][18][19][20][33][34][35][36]. In our study, the transparent segment of the rabbit carotid artery was vertically scanned along the z-axis using the computed tomography scanning capability of LSCM.…”

Section: Discussionmentioning

confidence: 99%

“…Several recent studies involving numerical simulations [17,18] or in vitro experiments [19,20] indicate that polarization of LDL concentration is indeed present in the vascular system. However, all the studies published to date have been limited to numerical simulations in computers and in vitro experimental methods, and have not reported the phenomenon of lipoprotein concentration polarization by real-time and quantitative methods in vivo.…”

Section: Introductionmentioning

confidence: 99%

In vitro and in vivo investigations on the effects of low-density lipoprotein concentration polarization and haemodynamics on atherosclerotic localization in rabbit and zebrafish

Xie

Tan

Wei

et al. 2013

J. R. Soc. Interface.

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Atherosclerosis (AS) commonly occurs in the regions of the arterial tree with haemodynamic peculiarities, including local flow field disturbances, and formation of swirling flow and vortices. The aim of our study was to confirm low-density lipoprotein (LDL) concentration polarization in the vascular system in vitro and in vivo, and investigate the effects of LDL concentration polarization and flow field alterations on atherosclerotic localization. Red fluorescent LDL was injected into optically transparent Flk1: GFP zebrafish embryos, and the LDL distribution in the vascular lumen was investigated in vivo using laser scanning confocal microscopy. LDL concentration at the vascular luminal surface was found to be higher than that in the bulk. The flow field conditions in blood vessel segments were simulated and measured, and obvious flow field disturbances were found in the regions of vascular geometry change. The LDL concentration at the luminal surface of bifurcation was significantly higher than that in the straight segment, possibly owing to the atherogenic effect of disturbed flow. Additionally, a stenosis model of rabbit carotid arteries was generated. Atherosclerotic plaques were found to have occurred in the stenosis group and were more severe in the stenosis group on a high-fat diet. Our findings provide the first ever definite proof that LDL concentration polarization occurs in the vascular system in vivo. Both lipoprotein concentration polarization and flow field changes are involved in the infiltration/accumulation of atherogenic lipids within the location of arterial luminal surface and promote the development of AS.

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“…Wall hemodynamic indicators such as wall pressure (WP), wall shear stress (WSS), and their spatial gradients (WPG and WSSG) have been investigated in curved arteries and a relationship between the predisposed sites of atherosclerosis formation and the regions of low WSS and WP or intense WPG and WSSG are proposed. 12,32,33 Rappitsch et al, 28 Hong et al, 14 and Wada et al 38 studied mass transfer in large single and multiple curved arteries in which local elevation of LDL concentration in the bend inner wall are found. The effects of stenosis in curved arteries are studied by Liu 19 and Yao et al 40 They found complex disturbed flow distal to plaque that may contribute to development of current lesions or genesis of new plaques.…”

Section: Introductionmentioning

confidence: 98%

Bend Sweep Angle and Reynolds Number Effects on Hemodynamics of S-Shaped Arteries

Niazmand

Jaghargh

2010

Ann Biomed Eng

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The purpose of this study is to investigate the effects of the Reynolds number and the bend sweep angle on the blood flow patterns of S-shaped bends. The numerical simulations of steady flows in S-shaped bends with sweep angles of 45 degrees , 90 degrees , and 135 degrees are performed at Reynolds numbers of 125, 500, and 960. Hemodynamic characteristics such as secondary flows, vorticity, and axial velocity profiles are analyzed in detail. Flow patterns in S-shaped bends are strongly dependent on both Reynolds number and bend sweep angle, which can be categorized into three groups based on the first bend secondary flow effects on the transverse flow of the second bend. For low Reynolds numbers and any sweep angles, secondary flows in the second bend eliminate the first bend effects in the early sections of the second bend and therefore the axial velocity profile is consistent with the bend curvature, while for high Reynolds numbers depending on the bend sweep angles the secondary vortex pattern of the first bend may persist partially or totally throughout the second bend leading to a four-vortex secondary structure. Moreover, an interesting flow feature observed at the Reynolds number of 960 is that the secondary flow asymmetrical behavior occurred around the second bend exit and along the outflow straight section. This symmetry-breaking phenomenon which has not been reported in the previous studies is shown to be more pronounced in the 90 degrees S-shaped bend as compared to other models considered here. The probability of flow separation as one of the important flow features contributing to the onset and development of arterial wall diseases is also studied. It is observed that the second bend outer wall of gentle bends with sweep angles from 20 degrees to 30 degrees at high enough Reynolds numbers are prone to flow separation.

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Blood flow and macromolecular transport in complex blood vessels

Cited by 15 publications

References 16 publications

A New Way to Reduce Flow Disturbance in Endovascular Stents: A Numerical Study

A New Way to Reduce Flow Disturbance in Endovascular Stents: A Numerical Study

In vitro and in vivo investigations on the effects of low-density lipoprotein concentration polarization and haemodynamics on atherosclerotic localization in rabbit and zebrafish

Bend Sweep Angle and Reynolds Number Effects on Hemodynamics of S-Shaped Arteries

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