Influence of pulsatile flow on LDL transport in the arterial wall.
The accumulation of low-density lipoprotein (LDL) is one of the important factors in atherogenesis. Two different time scales may influence LDL transport in vivo: (1) LDL transport is coupled to blood flow with a pulse cycle of around 1 s in humans; (2) LDL transport within the arterial wall is mediated by transmural flow in the order of 10(-8) m/s. Most existing models have assumed steady flow conditions and overlooked the interactions between physical phenomena with different time scales. The objective of this study was to investigate the influence of pulsatile flow on LDL transport and examine the validity of steady flow assumption. The effect of pulsatile flow on transmural transport was incorporated by using a lumen-free cyclic (LFC) and a lumen-free time-averaged (LFTA) procedures. It is found that the steady flow simulation predicted a focal distribution in the post-stenotic region, differing from the diffuse distribution pattern produced by the pulsatile flow simulation. The LFTA procedure, in which time-averaged shear-dependent transport properties calculated from instantaneous wall shear stress (WSS) were used, predicted a similar distribution pattern to the LFC simulations. We conclude that the steady flow assumption is inadequate and instantaneous hemodynamic conditions have important influence on LDL transmural transport in arterial geometries with disturbed and complicated flow patterns.
Sun
Nanfeng
N
Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK. nanfeng.sun@imperial.ac.uk
Wood
Nigel B
NB
Hughes
Alun D
AD
Thom
Simon A M
SA
Xu
X Yun
XY
D000818:Animals; D001158:Arteries / Q000502:physiology*; D001693:Biological Transport, Active; D001794:Blood Pressure / Q000502:physiology*; D002199:Capillary Permeability / Q000502:physiology; D003198:Computer Simulation; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008955:Models, Cardiovascular; D011673:Pulsatile Flow / Q000502:physiology*
D008077:Lipoproteins, LDL