血管支架内壁微织构参数对近壁面血流特性的影响

Effects of Micro Texture Parameters on Near Wall Blood Flow Characteristics of Vascular Stent

为了改善血管支架置入后近壁面的血流特性,抑制血管支架内血小板、脂类等物质的黏附,降低支架内出现再狭窄现象的概率,基于仿生学原理,在管状血管支架内表面设计了不同高度的正六边形凸起微织构,采用有限元法探究不同高度微织构在心脏收缩期和舒张期内对近壁面处血流状态的影响。结果表明,相比于无织构支架,内壁带有微织构的支架能够有效改善血流状态:在心脏收缩期,当血液流速达峰值时刻,微织构高度为35μm的支架下血流速度可提高0.78%,微织构高度为50μm的血管支架下血流速度能够提高8.93%;在心脏舒张期血液平稳流动时,微织构高度为35μm的支架下血流速度提高2.20%,微织构高度为50μm的血管支架下血液流速增幅达14.37%。尤其是在血液流速达峰值时,近壁面处的血液出现扰动和停滞区,随着微织构高度的增加,血液扰动的幅度逐渐增大;而当血液流动处于平稳状态,血液在近壁面产生漩涡和回流现象,微织构越高,血液回流量越小,漩涡强度越大。相比于无织构支架,微织构支架能够有效改善近壁面处的血流特性,提高血液流动速度和近壁面处的扰动,减少血液黏附,降低血管支架出现再狭窄的风险。

In order to improve the blood flow characteristics near the wall after vascular stent implantation,inhibit the adhesion of platelets,lipids and other substances in the vascular stent and reduce the probability of restenosis in the stent,regular hexagonal convex micro textures with different heights were designed on the inner surface of the tubular vascular stent based on the principle of bionics.The effects of different height micro textures on the blood flow near the wall during systole and diastole were studied by finite element method.The results show that compared with non textured stents,stents with micro texture on the inner wall can effectively improve the blood flow state.When the blood flow velocity reaches the peak value during cardiac systole,the blood flow velocity under stents with micro texture height of 35μm can be increased by 0.78%,and that under stents with micro texture height of 50μm can be increased by 8.93%;When the diastolic blood flows smoothly,the blood flow velocity under the stent with 35μm micro texture height can be increased by 2.20%,and the blood flow velocity under the stent with 50μm micro texture height can be increased by 14.37%.Especially when the blood velocity reaches the peak,the blood near the wall appears disturbance and stagnation zone.With the increase of micro texture height,the amplitude of blood disturbance increases gradually;When the blood flow is in a stable state,the blood produces vortex and backflow near the wall.The higher the micro texture,the smaller the blood backflow and the greater the vortex intensity.Compared with non textured stents,micro textured stents can effectively improve the blood flow characteristics near the wall,improve the blood flow velocity and disturbance near the wall,and reduce the risk of restenosis.