Augst A D, Ariff B, McG Thom S A G, Xu X Y, Hughes A D
Department of Chemical Engineering, Faculty of Engineering, Imperial College London, UK.
Am J Physiol Heart Circ Physiol. 2007 Aug;293(2):H1031-7. doi: 10.1152/ajpheart.00989.2006. Epub 2007 Apr 20.
Previous clinical studies have observed relationships between increased intima-media thickness (IMT) in the carotid artery, elevated blood pressure, and low wall shear stress (WSS) calculated from the Poiseuille equation. This study used numerical methods to more accurately determine WSS in the carotid artery and to investigate possible determinants of increased IMT.
IMT [common carotid artery (CCA) and bulb], CCA flow velocity, brachial systolic (SBP) and diastolic blood pressure (DBP), and carotid systolic pressure (cSBP) were measured in 14 healthy subjects (aged 44 +/- 16 yr). Flow patterns in the carotid bifurcation were determined by computational fluid dynamics (CFD) based on three-dimensional ultrasound geometry. Instantaneous and time-averaged wall shear stress (WSS(av)), oscillatory shear index (OSI), and wall shear stress angle gradients (WSSAG) were calculated.
IMT was positively related to SBP, DBP, cSBP, and WSSAG and inversely related to WSS(av) in the CCA. In the bulb, IMT was positively related to SBP and cSBP but was not significantly related to WSS(av) or WSSAG. IMT was unrelated to OSI in both the CCA and the bulb.
Increased carotid artery IMT in healthy subjects with no evidence of focal plaques is primarily a response to elevated pressure.
以往的临床研究观察到颈动脉内膜中层厚度（IMT）增加、血压升高与根据泊肃叶方程计算出的低壁面切应力（WSS）之间的关系。本研究采用数值方法更准确地测定颈动脉中的WSS，并探究IMT增加的可能决定因素。
对14名健康受试者（年龄44±16岁）测量了IMT[颈总动脉（CCA）和颈动脉球部]、CCA血流速度、肱动脉收缩压（SBP）和舒张压（DBP）以及颈动脉收缩压（cSBP）。基于三维超声几何结构，通过计算流体动力学（CFD）确定颈动脉分叉处的血流模式。计算了瞬时和时间平均壁面切应力（WSS(av)）、振荡切应力指数（OSI）和壁面切应力角梯度（WSSAG）。
在CCA中，IMT与SBP、DBP、cSBP和WSSAG呈正相关，与WSS(av)呈负相关。在颈动脉球部，IMT与SBP和cSBP呈正相关，但与WSS(av)或WSSAG无显著相关性。在CCA和颈动脉球部，IMT与OSI均无关。
在无局灶性斑块证据的健康受试者中，颈动脉IMT增加主要是对压力升高的一种反应。
