Flow patterns and velocity distributions in the human vertebrobasilar arterial system
Flow patterns and velocity distributions in the human vertebrobasilar arterial system
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DOI：
10.3171/2010.1.jns09575
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发表时间：
2010-10-01
影响因子：
4.1
通讯作者：
Karino, Takeshi
中科院分区：
文献类型：
--
作者：
Kobayashi, Nobuaki;Karino, Takeshi
对象。作者对基底动脉（BA）分叉处的血流模式与动脉瘤形成的关系进行了研究。从人的尸体中制备了6个分离的透明椎基底动脉系统，并使用血流可视化和电影显微摄影技术详细研究了血流模式和速度分布。作者发现，如果2条椎动脉（VAs）的直径接近相等，并与BA形成对称的倒y型连接，则BA的流量也是对称的。从2个VAs流入BA的流体元素几乎平行于BA的血管壁而不相互混合，然后它们通过同侧小脑上动脉和大脑后动脉流出。与此相反，如果两个VAs的直径相差很大，或者BA弯曲严重，则BA流动受到干扰，形成旋流和二次流。当倒y结对称时，BA末端分岔处的接近速度曲线变平，当倒y结不对称时，接近速度曲线变尖。因此，在后一种情况下，与对称倒y结的情况相比，流体元件以更大的速度撞击分岔分流器周围的血管壁，从而产生更大的动能，在那里的血管壁上施加高流体压力、壁面剪切应力和壁面张力。正常椎基底动脉系统中倒y结的对称结构提供了BA末端分叉处平坦的接近速度剖面，降低了施加在分叉壁上的血流动力学应力（压力、张力和剪切应力）。这可能是该部位动脉瘤形成发生率相对较低的原因。(DOI: 10.3171 / 2010.1.jns09575)
Object. The authors conducted a study to elucidate the relationship between the flow patterns and the formation of aneurysms at the bifurcation of the basilar artery (BA).Methods. Six isolated, transparent vertebrobasilar arterial systems were prepared from humans postmortem, and flow patterns and velocity distributions were studied in detail using flow visualization and cinemicrographic techniques.Results. The authors found that if the diameters of 2 vertebral arteries (VAs) were nearly equal and they formed a symmetrical inverted Y-shaped junction with the BA, the BA flow was also symmetrical. The fluid elements that flowed into the BA from 2 VAs traveled almost parallel to the vessel wall of the BA without mixing with each other, and then they flowed out through ipsilateral superior cerebellar and posterior cerebral arteries. In contrast to this, if the diameters of 2 VAs were very different or the BA was badly bent, the BA flow was disturbed as a result of the formation of swirling and secondary flows. The approaching velocity profile at the BA's terminal bifurcation was flattened if the inverted Y-junction was symmetrical, and it was sharpened if the junction was asymmetrical. Thus, in the latter case, fluid elements impinged on the vessel wall around the flow divider of the bifurcation with much larger velocities and, hence, larger kinetic energy, compared with the case of a symmetrical inverted Y-junction, exerting high fluid pressures, wall shear stresses, and wall tensions on the vessel wall there.Conclusions. The symmetrical structure of the inverted Y-junction in a normal vertebrobasilar arterial system provides a flattened approaching velocity profile at the terminal bifurcation of the BA, lowering the hemodynamic stresses (pressure, tension, and shear stress) exerted on the wall of the bifurcation. This may account for the relatively low incidence of aneurysm formation at this site. (DOI:10.3171/2010.1.JNS09575)