Salzmann D L, Yee D C, Roach D J, Berman S S, Williams S K
Department of Surgery, University of Arizona Health Sciences Center, Tucson 85724, USA.
J Biomed Mater Res. 1998 Sep 5;41(3):364-70. doi: 10.1002/(sici)1097-4636(19980905)41:3<364::aid-jbm4>3.0.co;2-a.
Deployment of endovascular grafts composed of a metallic stent surrounded by expanded polytetrafluoroethylene (ePTFE) stretches the polymer beyond its original dimensions, altering the structural characteristics of the ePTFE. We hypothesized this structural modification would alter the healing response associated with the implant. In this study, 4 mm i.d. of ePTFE (30 microns internodal distance) vascular grafts were balloon dilated using angioplasty balloons having final diameters of 6 (1.5X), 8 (2X), 10 (2.5X), 12 (3X), and 18 (4.5X) mm. Following balloon dilatation of the ePTFE, a circular punch (6 mm in diameter) was used to prepare polymer samples for implantation. The ePTFE circular patches were implanted within subcutaneous tissue and epididymal fat pads of male Sprague-Dawley rats. After 5 weeks, the implants were removed and analyzed for fibrous capsule formation, inflammation, and neovascularization associated with the material. Histological analysis revealed the formation of fibrous capsules only with control subcutaneous implants. The inflammatory response associated with subcutaneously implanted ePTFE was decreased significantly following balloon dilatation to at least 2.5 times the original diameter of the graft. In contrast, ePTFE implanted within adipose tissue demonstrated a significantly greater inflammatory response following balloon dilatation when compared to control implants. Only ePTFE balloons dilated to 6 mm and implanted within adipose tissue demonstrated neovascularization to any extent. These data suggest the structural modifications incurred by ePTFE following balloon dilatation dramatically affect the inflammatory response associated with an implant. Therefore, polymeric materials used for endovascular graft technology require designs that consider changes in polymer healing inherent to device design.
由金属支架和周围的膨体聚四氟乙烯（ePTFE）组成的血管内移植物的展开会使聚合物伸展至其原始尺寸之外，从而改变ePTFE的结构特征。我们推测这种结构改变会改变与植入物相关的愈合反应。在本研究中，使用最终直径为6（1.5倍）、8（2倍）、10（2.5倍）、12（3倍）和18（4.5倍）mm的血管成形术球囊对内径为4 mm的ePTFE（节距30微米）血管移植物进行球囊扩张。在对ePTFE进行球囊扩张后，使用直径6 mm的圆形穿孔器制备用于植入的聚合物样本。将ePTFE圆形补片植入雄性Sprague-Dawley大鼠的皮下组织和附睾脂肪垫内。5周后，取出植入物并分析与该材料相关的纤维囊形成、炎症和新生血管情况。组织学分析显示仅对照皮下植入物形成了纤维囊。球囊扩张至移植物原始直径的至少2.5倍后，皮下植入ePTFE相关的炎症反应显著降低。相比之下，与对照植入物相比，脂肪组织内植入的ePTFE在球囊扩张后表现出明显更强的炎症反应。仅球囊扩张至6 mm并植入脂肪组织的ePTFE在一定程度上显示出新生血管形成。这些数据表明，球囊扩张后ePTFE发生的结构改变会显著影响与植入物相关的炎症反应。因此，用于血管内移植物技术的聚合物材料需要设计时考虑到设备设计中聚合物愈合的变化。
