Murphy J G, Schwartz R S, Edwards W D, Camrud A R, Vlietstra R E, Holmes D R
Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, Rochester, Minn. 55905.
Circulation. 1992 Nov;86(5):1596-604. doi: 10.1161/01.cir.86.5.1596.
To test the feasibility of percutaneous deployment of intracoronary polymeric stents, a prototype polyethylene terephthalate (PET) stent and a catheter-based delivery system were developed.
Polymeric stents were deployed in the coronary arteries of 11 Yucatan swine: six stents were placed in the left anterior descending coronary artery, four stents were placed in the circumflex artery, and one stent was placed in the right coronary artery. Stent deployment was achieved by withdrawal of an outer delivery sheath, thus allowing the PET stent to self-expand to a preformed configuration. Two animals died during surgery, one during stent placement and the other several hours after implantation due to intracoronary thrombus formation. Two animals were electively sacrificed within 24 hours of stent implant to examine the adequacy of stent deployment within the coronary vessel. The remaining seven animals survived until the termination of the study 4-6 weeks later. Light microscopic examination of the stented vessels showed an extensive neointimal proliferative response with vessel occlusion in all animals who survived initial stent placement. There were two distinct types of histological responses to the PET stent--a chronic foreign body inflammatory response around the stent tines and a neointimal proliferative response in the center of the occluded vessel lumen. The histological response seen in the central area of the vessel was morphologically similar to that seen in patients with restenosis after successful percutaneous transluminal coronary angioplasty, whereas the morphological response seen at the periphery of the stent tine was similar to that exhibited by a chronic foreign body reaction and was not typical of that seen in a restenosis lesion. A ventricular aneurysm also developed in the area of myocardium that was previously supplied by the occluded vessel.
This study demonstrates that percutaneous deployment of polymeric stents in the coronary arteries is technically feasible. The use of PET polymer was associated with an intense proliferative neointimal response that resulted in complete vessel occlusion. Histological examination of the stented segments of the vessel revealed no evidence that dissection of the vessel wall had occurred at the time of initial stent deployment. Although the PET polymer was of similar quality to that used in the manufacture of balloon angioplasty catheters, a toxic chemical or contaminant effect cannot be completely excluded as the stimulus to intimal proliferation. This finding may have relevance to the selection of materials for use as intravascular devices.
为了测试经皮冠状动脉内植入聚合物支架的可行性，研发了一种聚对苯二甲酸乙二酯（PET）支架原型及基于导管的输送系统。
在11只尤卡坦猪的冠状动脉内植入聚合物支架：6个支架置于左前降支冠状动脉，4个支架置于回旋支动脉，1个支架置于右冠状动脉。通过抽出外部输送鞘实现支架植入，从而使PET支架自行扩张至预成型状态。两只动物在手术过程中死亡，一只在植入支架时死亡，另一只在植入后数小时因冠状动脉内血栓形成死亡。两只动物在植入支架后24小时内被选择性处死，以检查冠状动脉内支架植入的充分性。其余7只动物存活至4 - 6周后研究结束。对植入支架的血管进行光镜检查发现，所有在初次植入支架后存活的动物均出现广泛的新生内膜增殖反应并伴有血管闭塞。对PET支架有两种不同类型的组织学反应——支架尖周围的慢性异物炎症反应和闭塞血管腔中心的新生内膜增殖反应。在血管中心区域观察到的组织学反应在形态上与成功进行经皮腔内冠状动脉成形术后再狭窄患者的反应相似，而在支架尖周边观察到的形态学反应与慢性异物反应相似，并非再狭窄病变中典型的反应。在先前由闭塞血管供血的心肌区域还形成了室壁瘤。
本研究表明经皮冠状动脉内植入聚合物支架在技术上是可行的。使用PET聚合物会引发强烈的新生内膜增殖反应，导致血管完全闭塞。对血管植入支架部分的组织学检查未发现初次植入支架时血管壁发生夹层的证据。尽管PET聚合物的质量与用于制造球囊血管成形术导管的材料相似，但作为内膜增殖的刺激因素，不能完全排除有毒化学物质或污染物的影响。这一发现可能与血管内装置材料的选择有关。
