血流剪切力对支架内新生动脉粥样硬化形成的影响

Effect of Shear Stress on the Formation of In-stent Neoatherosclerosis

目的:探讨血流剪切力对支架内新生粥样硬化斑块形成的影响。方法:在6只新西兰白兔右髂动脉植入金属裸支架,术后高脂喂养8周。将支架按长度均等分为近中远3段,应用多普勒超声测量各支架段血管的血流速度和血管内径,根据Poiseuille定律计算出术后即刻及术后8周时各支架段的平均血流剪切力。应用光学相干断层成像技术(optical coherence tomography,OCT)检测术后8周支架内新生内膜的生长情况及特性。结果:成功建立支架内斑块动物模型。术后即刻近中远支架段的血流剪切力分别为4.25±0.92,2.49±1.07,1.67±0.49Pa(P<0.05);术后8周近中远支架段血流剪切力分别为20.40±6.07,11.09±1.74,7.97±0.26Pa(P<0.05),均较术后即刻明显升高(P<0.001);术后8周近中远支架段的内膜异质性发生率分别为86.67%,53.33%,41.12%(P<0.05);术后8周近中远支架段OCT检测的富含脂质斑块的发生率分别为53.3%,20%,0%(P<0.05)。结论:支架内新生粥样硬化斑块的发生可能与较高的血流剪切力相关。

Objective： To study the impact of shear stress on the formation of in-stent neoatherosclerosis. Methods： The bare-metal stents were implanted in the right iliac arteries of 6 New Zealand White rabbits, which were then fed with a high-fat diet for additional 8 weeks. Each implanted stent was equally divided into 3 segments and the blood flow velocity and blood vessel diameter was measured with Doppler ultrasound. The average shear stress forces were calculated immediately after and 8 weeks after stent implantation according to Poiseuille＇s law. The characteristics of in-stent neointima 8 weeks after stent implantation were evaluated using optical coherence tomography. Results： An experimental animal model of in-stent neoatherosclerosis was successfully established. Shear stress forces of the proximal-, middle-and distal-stent segments were 4.25±0.92, 2.49±1.07, 1.67±0.49 Pa（P〈0.05） immediately after stent implantation, which significantly increased to 20.40 ±6.07, 11.09 ±1.74, 7.97 ±0.26 Pa respectively（P〈0.05） after 8 weeks（the differences between baseline and follow-up, all P〈0.001）.The incidence of neointima heterogeneity of proximal-, middle-, distal-stent segments 8 weeks after stent implantation were 86.67%,53.33%,41.12%（P〈0.05） and the occurrences of in-stent neoatherosclerosis of the 3 segments were 53.3%, 20%, 0% respectively（P〈0.05）. Conclusions： These data suggests that the formation of in-stent neoatherosclerosis may be associated with higher shear stress.