Dolmatch Bart, Dong Yong-Hua, Heeter Zachary
UT Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd, Dallas, TX 75390, USA.
J Vasc Interv Radiol. 2007 Apr;18(4):527-34. doi: 10.1016/j.jvir.2007.02.011.
The authors tested three different porosities of expanded polytetrafluoroethylene (ePTFE)-covered stents and bare stents by using an animal model of restenosis.
Both iliac arteries in 18 female pigs were injured by overdilating 20-mm-long angioplasty balloons. A 40-mm-long bare stent or one of three 44-mm-long ePTFE-covered stents was deployed at the injury site. To determine restenosis, neointimal area measurements were made with intravascular ultrasonography. Histologic analyses were performed at an independent laboratory to determine neointimal attachment.
Neointimal area was greatest at the middle of the bare stent, where balloon injury was centered. When the middle location of the covered stents was evaluated, the neointimal area of both the medium- and high-porosity covered stents was smaller than that of the matched control stents (P = .0018 and P = .0118, respectively). The neointimal area of the low-porosity covered stents was similar to that of the bare stents. Histologic study showed dehiscence of the neointima of the low-porosity covered stents.
The microstructure of the low-porosity covered stents did not provide a suitable surface for neointimal attachment and did not reduce neointimal growth compared to that with the control stents. The microstructure of the medium- and high-porosity covered stents yielded less neointimal growth than both the control stents and the low-porosity covered stents without evidence of neointimal dehiscence. The authors believe that covered stents made with ePTFE with either medium or high porosity could limit restenosis in humans compared to that with bare stents.
作者通过使用再狭窄动物模型，测试了三种不同孔隙率的膨体聚四氟乙烯（ePTFE）涂层支架和裸支架。
对18头雌性猪的双侧髂动脉进行过度扩张20毫米长的血管成形术球囊损伤。在损伤部位植入一个40毫米长的裸支架或三个44毫米长的ePTFE涂层支架之一。为了确定再狭窄情况，采用血管内超声测量新生内膜面积。在独立实验室进行组织学分析以确定新生内膜附着情况。
裸支架中部的新生内膜面积最大，此处为球囊损伤的中心部位。在评估涂层支架的中部位置时，中孔隙率和高孔隙率涂层支架的新生内膜面积均小于匹配的对照支架（分别为P = 0.0018和P = 0.0118）。低孔隙率涂层支架的新生内膜面积与裸支架相似。组织学研究显示低孔隙率涂层支架的新生内膜有裂开。
低孔隙率涂层支架的微观结构未为新生内膜附着提供合适表面，与对照支架相比未减少新生内膜生长。中孔隙率和高孔隙率涂层支架的微观结构导致的新生内膜生长少于对照支架和低孔隙率涂层支架，且无新生内膜裂开迹象。作者认为，与裸支架相比，中孔隙率或高孔隙率的ePTFE制成的涂层支架可能会限制人类的再狭窄。
