Ku D N, Giddens D P, Zarins C K, Glagov S
Arteriosclerosis. 1985 May-Jun;5(3):293-302. doi: 10.1161/01.atv.5.3.293.
Fluid velocities were measured by laser Doppler velocimetry under conditions of pulsatile flow in a scale model of the human carotid bifurcation. Flow velocity and wall shear stress at five axial and four circumferential positions were compared with intimal plaque thickness at corresponding locations in carotid bifurcations obtained from cadavers. Velocities and wall shear stresses during diastole were similar to those found previously under steady flow conditions, but these quantities oscillated in both magnitude and direction during the systolic phase. At the inner wall of the internal carotid sinus, in the region of the flow divider, wall shear stress was highest (systole = 41 dynes/cm2, diastole = 10 dynes/cm2, mean = 17 dynes/cm2) and remained unidirectional during systole. Intimal thickening in this location was minimal. At the outer wall of the carotid sinus where intimal plaques were thickest, mean shear stress was low (-0.5 dynes/cm2) but the instantaneous shear stress oscillated between -7 and +4 dynes/cm2. Along the side walls of the sinus, intimal plaque thickness was greater than in the region of the flow divider and circumferential oscillations of shear stress were prominent. With all 20 axial and circumferential measurement locations considered, strong correlations were found between intimal thickness and the reciprocal of maximum shear stress (r = 0.90, p less than 0.0005) or the reciprocal of mean shear stress (r = 0.82, p less than 0.001). An index which takes into account oscillations of wall shear also correlated strongly with intimal thickness (r = 0.82, p less than 0.001). When only the inner wall and outer wall positions were taken into account, correlations of lesion thickness with the inverse of maximum wall shear and mean wall shear were 0.94 (p less than 0.001) and 0.95 (p less than 0.001), respectively, and with the oscillatory shear index, 0.93 (p less than 0.001). These studies confirm earlier findings under steady flow conditions that plaques tend to form in areas of low, rather than high, shear stress, but indicate in addition that marked oscillations in the direction of wall shear may enhance atherogenesis.
在人体颈动脉分叉的比例模型中，通过激光多普勒测速仪在脉动流条件下测量流体速度。将五个轴向和四个周向位置处的流速和壁面剪应力与从尸体获得的颈动脉分叉相应位置处的内膜斑块厚度进行比较。舒张期的速度和壁面剪应力与先前在稳定流条件下发现的相似，但这些量在收缩期的大小和方向上都有振荡。在内颈动脉窦的内壁，在分流器区域，壁面剪应力最高（收缩期 = 41 达因/平方厘米，舒张期 = 10 达因/平方厘米，平均值 = 17 达因/平方厘米），并且在收缩期保持单向。该位置的内膜增厚最小。在颈动脉窦外壁内膜斑块最厚的地方，平均剪应力较低（-0.5 达因/平方厘米），但瞬时剪应力在 -7 至 +4 达因/平方厘米之间振荡。沿着窦的侧壁，内膜斑块厚度大于分流器区域，并且剪应力的周向振荡很明显。考虑所有 20 个轴向和周向测量位置，发现内膜厚度与最大剪应力的倒数（r = 0.90，p 小于 0.0005）或平均剪应力的倒数（r = 0.82，p 小于 0.001）之间存在强相关性。一个考虑壁面剪应力振荡的指标也与内膜厚度密切相关（r = 0.82，p 小于 0.001）。当仅考虑内壁和外壁位置时，病变厚度与最大壁面剪应力和平均壁面剪应力的倒数的相关性分别为 0.94（p 小于 0.001）和 0.95（p 小于 0.001），与振荡剪应力指数的相关性为 0.93（p 小于 0.001）。这些研究证实了早期在稳定流条件下的发现，即斑块倾向于在低剪应力而非高剪应力区域形成，但此外还表明壁面剪应力方向的明显振荡可能会促进动脉粥样硬化的发生。
