螺旋型人工血管内的血流动力学数值模拟

Numerical simulation of hemodynamics in spiral artificial blood vessel

针对过低的壁面剪切应力(WSS)会引起小口径人工血管移植后发生再狭窄的问题,探讨了旋动流对WSS等血流动力学因素的影响,构建了螺旋型人工血管与宿主血管的端侧吻合模型,通过有限元数值模拟证实了旋动流的形成,并探讨了吻合角、螺旋半径、螺距等参数对模型脚趾处(易发内膜增生部位)WSS的影响。结果表明:吻合角较小(30°)时,1个周期内的时均壁面剪切应力(TAWSS)最低值为1.2 Pa,高于吻合角为45°和60°时的0.3和0.4 Pa;螺旋半径分别为1.0、1.5、2.0 mm时,TAWSS最低值分别为0.69、0.68、1.06 Pa,较大螺旋半径对提升WSS更有利;螺距从96 mm逐步降低为48、32 mm时,TAWSS最低值从0.77 Pa逐步提升到1.06、1.30 Pa,螺距较小时TAWSS最低值相对较高。

Low wall shear stress(WSS)is one of the mechanical causes for restenosis after vascular transplantation.In order to investigate the effect of swirling flow on hemodynamics such as WSS,an end-to-side anastomotic model between the spiral artificial blood vessel and the host vessel was constructed.The formation of swirling flow was confirmed by finite element numerical simulation,and the effects of anastomotic angle,spiral radius and pitch on WSS in the toe of the model(an area prone to intimal hyperplasia)were discussed.The results show that the lowest value of the time average wall shear stress(TAWSS)in a cardiac cycle is 1.2 Pa when the anastomotic angle is 30°,which are higher than the values of 0.3 Pa(45°)and 0.4 Pa(60°)respectively.When the spiral radius is 1.0,1.5 and 2.0 mm,the corresponding minimum TAWSS is 0.69,0.68 and 1.06 Pa respectively,which shows larger spiral radius is more favorable to improve the WSS.When the pitch gradually decreases from 96 mm to 48 and 32 mm,the minimum TAWSS gradually increases from 0.77 Pa to 1.06 and 1.30 Pa.It shows that when the pitch is small,the minimum TAWSS is high.