Dipartimento del Cuore e dei Vasi, Azienda Ospedaliero-Universitaria Careggi, Firenze, Italy.
Atherosclerosis. 2011 Feb;214(2):249-56. doi: 10.1016/j.atherosclerosis.2010.09.008. Epub 2010 Sep 18.
Atherosclerosis is the main cause of morbidity and mortality in the Western world. Inflammation and blood flow alterations are new markers emerging as possible determinants for the development of atherosclerotic lesions. In particular, blood flow exerts a shear stress on vessel walls that alters cell physiology. Shear stress arises from the friction between two virtual layers of a fluid and is induced by the difference in motion and viscosity between these layers. Regions of the arterial tree with uniform geometry are exposed to a unidirectional and constant flow, which determines a physiologic shear stress, while arches and bifurcations are exposed to an oscillatory and disturbed flow, which determines a low shear stress. Atherosclerotic lesions develop mainly in areas of low shear stress, while those exposed to a physiologic shear stress are protected. The presence of areas of the arterial tree with different wall shear stress may explain, in part, the different localization of atherosclerotic lesions in both coronary and extracoronary arteries. The measurement of this parameter may help in identifying atherosclerotic plaques at higher risk as well as in evaluating the efficacy of different pharmacological interventions. Moreover, an altered shear stress is associated with the occurrence of both aortic and intracranial aneurysms, possibly leading to their growth and rupture. Finally, the evaluation of shear stress may be useful for predicting the risk of developing restenosis after coronary and peripheral angioplasty and for devising a coronary stent with a strut design less thrombogenic and more conducive to endothelization.
动脉粥样硬化是西方世界发病率和死亡率的主要原因。炎症和血流改变是新兴的可能决定动脉粥样硬化病变发展的标志物。特别是，血流对血管壁施加切变应力，改变细胞生理学。切变应力源于两层虚拟流体之间的摩擦力，并由这些层之间的运动和粘度差异引起。具有均匀几何形状的动脉树区域暴露于单向和恒定的流动，这决定了生理切变应力，而拱和分叉暴露于振荡和紊乱的流动，这决定了低切变应力。动脉粥样硬化病变主要发生在低切变应力区域，而暴露于生理切变应力的区域则受到保护。动脉树不同壁切变应力区域的存在可能部分解释了冠状动脉和体外动脉中动脉粥样硬化病变的不同定位。该参数的测量有助于识别具有更高风险的动脉粥样硬化斑块，以及评估不同药物干预的疗效。此外，切变应力的改变与主动脉和颅内动脉瘤的发生有关，可能导致其生长和破裂。最后，评估切变应力可能有助于预测冠状动脉和外周血管成形术后再狭窄的风险，并设计具有较低血栓形成和更有利于内皮化的支撑设计的冠状动脉支架。
