生物可降解心血管支架与人体相容性的系统评价

背景：冠状动脉支架置入后的再狭窄等并发症越来越引起关注。 目的：系统评价生物可降解心血管支架材料与人体相容性的研究。 方法：计算机检索 EMbase(1980/2011-08)、MEDLINE(1966/2011-08)和中国生物医学文献数据库(CBM,1978/2011-08)、中文学术期刊全文数据库(CNKI),筛查相关文章的参考文献收集发表的生物可降解心血管支架生物相容性的动物实验和临床实验中文献,对可降解心血管支架材料生物相容性的总结。 结果与结论：当血管内皮化完成之后,生物可降解支架如期降解,从而克服了支架本身作为异物的血栓源性,抑制早期血栓形成及晚期新生内膜增生,具有良好的生物相容性,有效降低了再狭窄的发生率。同时,生物可降解支架还可作为药物局部投放的载体,达到有效防止支架置入后血管急性闭塞和降低再狭窄发生率。     

可吸收镁合金支架植入后犬冠状动脉C-反应蛋白、基质金属蛋白酶9和血管性血友病因子的表达

背景:课题组前期研究从宏观角度验证了可吸收镁合金支架的生物安全性。目的:观察可吸收镁合金支架植入后局部血管组织C-反应蛋白、基质金属蛋白酶9及血管性血友病因子的表达情况,从分子表达水平深层次探讨镁合金支架的组织相容性及安全性。方法:将25枚可吸收镁合金支架植入25只防疫杂种犬冠状动脉前降支或左回旋支,未植入支架的5只犬冠状动脉作为正常对照组,支架植入后24 h、3 d、5 d、1周、1个月各处死动物5只,取支架植入后的血管标本做病理切片,应用免疫组织化学染色方法测定冠状动脉局部C-反应蛋白、基质金属蛋白酶9及血管性血友病因子的表达。结果与结论:与正常对照组比较,支架植入后不同时间点冠状动脉局部C-反应蛋白、基质金属蛋白酶9及血管性血友病因子阳性细胞数明显增多(P0.01),A值显著升高(P0.01);与支架植入24 h、3 d、5 d、1周比较,植入1个月后冠状动脉局部C-反应蛋白、基质金属蛋白酶9及血管性血友病因子阳性细胞数明显减少(P0.01),A值显著降低(P0.01)。结果表明可吸收镁合金支架植入后的组织炎症程度轻,持续时间短且无血栓形成,提示可吸收镁合金支架具有较好的组织相容性和安全性。     

冠状动脉支架表面涂层材料对置入效果的影响

目的:阐述冠状动脉内支架的临床应用进展,并探讨冠状动脉支架的表面涂层材料对置入后支架内血栓形成和再狭窄的影响。方法:作者以"冠脉内支架,表面涂层,血栓,再狭窄"为检索词,在中国期刊全文数据库(CNKI:2002/2008)及Medline数据库(PubMed:1974/2006)中,采用电子检索的方式进行文献检索。排除Meta分析及重复性研究,共检索到25篇文献,从冠状动脉内支架置入治疗进展,不同表面涂层材料及其对支架内血栓形成和再狭窄的影响等方面进行探讨。结果:冠状动脉内药物洗脱支架置入是治疗冠心病的常用方法,效果明显,并发症很少。冠状动脉内支架表面涂层材料有雷帕霉素、紫杉醇、肝素、二烯丙基三硫化物、地塞米松以及不可降解的聚合物等,均能促进内皮细胞修复,抑制平滑肌细胞增殖,防治支架内血栓形成和再狭窄,保持支架的通畅。由于残留的涂层材料刺激平滑肌细胞增殖,近年使用的可降解的聚合物涂层能进一步提高支架的通畅率。如肝素化聚氨酯涂层、聚乳酸聚羟基乙酸共聚物雷帕霉素涂层和聚砜-聚氧化乙酸共聚物雷帕霉素涂层具有良好的组织相容性,抑制内膜增生,改善再狭窄,有望成为新的冠状动脉内支架涂层材料。结论:冠状动脉内药物洗脱支架置入和阿司匹林、氯吡格雷联合应用是冠状动脉血运重建的良好方法,随着涂层材料的不断更新,支架的通畅率将得到进一步提高。     

新型生物全降解药物支架置入小型猪冠状动脉的安全性

背景：目前冠状动脉支架的主要研究方向是高生物相容性的全降解生物材料及药物控释体系。 目的：评价2种新型生物全降解药物支架置入小型猪冠状动脉后的安全性。 方法：普通生物全降解支架为在聚左旋乳酸本体中融入抗增殖药物紫杉醇,新型生物全降解支架为在聚左旋乳酸及紫杉醇的基础上融入一种新型纳米材料无定形磷酸钙。①将普通生物全降解支架和新型生物全降解支架各5枚在冠状动脉造影下分别随机置入小型猪的冠状动脉,每种支架5头。于置入前和置入后28 d行血生化及C-反应蛋白水平检测;术后28 d冠状动脉造影观察支架置入段管腔通畅情况。②在微创显微镜辅助下于兔右髂外动脉分别置入普通生物全降解支架和新型生物全降解支架管状半成品(材料成分与上述支架一致),每种支架7只,在术前和术后28 d检测血尿素氮及肌酐水平。 结果与结论：置入后28 d两组猪谷丙转氨酶、谷草转氨酶、三酰甘油、总胆固醇、低密度脂蛋白及C-反应蛋白水平与置入前相比均无明显变化,但尿素氮、肌酐水平均明显高于置入前(P < 0.05);两组支架置入段血管均血流通畅、无血栓迹象和狭窄形成。支架置入前后两组兔肌酐和尿素氮水平无明显变化。表明新型生物全降解药物支架置入健康小型猪冠状动脉后是相对安全的,并且支架具有良好的组织相容性。     

冠状动脉支架置入后的血小板活化及其生物相容性

目的:评价冠状动脉支架置入后的生物相容性,探讨冠状动脉支架置入后血小板活化与支架再狭窄的关系。方法:用计算机检索中国期刊全文数据库(1990/2009)和Pubmed数据库(1990/2009),以"冠状动脉支架,血小板活化,生物相容性"或"coronary artery stent,platelet activation,biocompatibility"为检索词进行检索。纳入主题内容与冠状动脉支架置入后的生物相容性以及支架置入后血小板活化与支架再狭窄关系联系紧密的文章;排除Meta分析及重复性研究。结果:冠状动脉支架置入后损伤血管壁从而激活机体的免疫应答过程。内皮细胞、血小板和炎性白细胞释放的生长因子及细胞因子,最终促使血管平滑肌细胞增殖是导致再狭窄的根本原因。文章研究了冠状动脉支架置入后血小板活化与支架再狭窄的关系及其各种冠状动脉支架置入后的生物相容性评价,并展望了生物可降解支架的发展前景。结论:生物可降解支架不仅能够将再狭窄的可能性降至最小,而且提供了对抗血栓的保护作用,这些都为支架置入后血管再狭窄问题的解决带来了新的希望。     

生物可吸收涂层和永久涂层药物支架治疗冠状动脉粥样硬化性心脏病的Meta分析

背景:生物可吸收涂层药物支架和永久涂层药物支架均广泛应用于冠状动脉粥样硬化性心脏病介入治疗中,由于支架架构、支架药物、药物载体上的差异,多个研究对两种支架疗效和安全性的比较结果不完全一致。目的:比较生物可吸收涂层药物支架和永久涂层药物支架在冠状动脉粥样硬化性心脏病介入治疗的临床结果,评价两类支架在疗效和安全性上的差异。方法:检索Medline(1966-01/2010-07)、Embase(1980-01/2010-07)、Cochrane library(2010-07)、中国生物医学文献数据库(CBM,1990-01/2010-07)及相关参考文献,收集比较生物可吸收涂层药物支架与永久涂层药物支架的对照研究,采用Cochrane的随机方法学评价文献质量,应用RevMan5.0软件进行Meta分析。结果与结论:纳入10个对照研究,共纳入4391例患者,其中生物可吸收涂层药物支架组2429例,永久涂层药物支架组1962例。Meta分析结果显示,生物可吸收涂层药物支架用于冠状动脉粥样硬化性心脏病患者,支架置入后6～12个月内心脏主要不良事件、靶血管血运重建、心脏性死亡、再发心肌梗死、支架内血栓形成和支架内再狭窄与永久涂层药物支架组差异无显著性意义。但生物可吸收涂层药物支架内晚期管腔丢失明显小于永久涂层药物支架组(P0.05)。提示生物可吸收涂层药物支架用于治疗冠状动脉粥样硬化性心脏病安全、有效,并不劣于永久涂层药物支架,且可能在减轻冠状动脉支架置入治疗后内膜过度增生方面更具优势。     

可降解脑血管支架材料生物相容性的系统评价

背景：选择和开发具有良好生物相容性的脑血管支架材料是目前研究的热点。 目的：系统评价可降解脑血管支架材料生物相容性的相关文献,客观分析生物可降解支架置入的安全性及预后。 方法：计算机检索EMbase(1980/2011-08)、MEDLINE(1966/2011-08)、中国生物医学文献数据库(CBM,1978/2011-08)、中文学术期刊全文数据库(CNKI)有关可降解脑血管支架生物相容性的动物实验和临床试验的文献,进行可归纳总结。 结果与结论：共纳入24篇文章,15篇有关可降解脑血管支架材料生物相容性的动物实验结论均显示,多种可降解脑血管支架材料可抑制内膜增生,防止血栓形成,再狭窄发生率低,生物相容性良好;9篇有关可降解脑血管支架材料生物相容性的临床应用文章显示,可降解脑血管支架可减少再狭窄,改善患者预后,其安全性能尚待更长期的观察。提示可降解脑血管支架材料具有良好的生物相容性,作为支架置入材料应用于脑血管疾病的治疗具有较高的安全性及有效性,其减少再狭窄率的长期疗效有待于进一步观察。     

载药复合支架的抗血管组织增生的研究

在氧化钛表面改性的国产不锈钢支架上涂覆一定量药物,制备出新型复合的抗增生载药支架.观察支架植入猪冠状动脉3个月后血管的开通情况及血管的内膜反应.将7枚国产的普通不锈钢支架和7枚制备的新型载药支架植入14头小型猪冠状动脉内,3个月后对支架植入段血管进行血管造影、光镜及电镜检查并进行免疫组织化学分析.冠状动脉造影显示动物处死前支架段血管开通率100%,支架X光下清晰可见,未经特殊抗血栓治疗,支架段血管内无血栓形成.扫描电镜显示两组支架表面都完全被血管内膜覆盖,表面光滑,无血栓形成.覆盖的血管内膜中内皮细胞沿血流方向成典型的铺路石状排列.组织学形态分析显示植入支架3个月后,所有支架植入段血管内膜都有明显的增生,增生内膜主要由细胞外基质和平滑肌细胞构成.结论:含有新型载药支架的冠状动脉血管段内膜增生厚度比普通不锈钢支架的冠状动脉血管段内膜增生厚度小,这种载药复合支架具有良好的应用前景,需扩大样本进行深入研究.     

大蒜素包被支架术后冠状动脉管壁原癌基因c-fos表达的变化

目的：探讨大蒜素（DT）包被支架置入后对血管内膜增生及管壁原癌基因c-fos表达的影响。方法：直接支架置入术建立犬冠状动脉内膜损伤模型，观察血管形态学变化，并用RT-PCR方法检测不同时点冠状动脉壁内c-fos基因的表达丰度。结果：单纯蛋白包被支架置入后4周管壁内膜明显增生，DT包被支架明显抑制内膜增生。对照组c-fos基因在术后1 d有大量的表达，7 d达高峰，以后随时间的推移表达逐渐下降,28 d仍可检出。与对照组相比，各时点DT包被支架均显著抑制c-fos mRNA的表达。结论：DT包被支架具有抑制c-fos基因的表达与内膜增生的作用。     

冠状动脉支架材料与置入后炎症因子的变化

目的：总结冠状动脉支架材料及置入后炎症因子变化的关系。 方法：以“冠状动脉支架,生物相容性,炎症因子,细胞因子,血栓”为关键词,采用计算机检索万方数据网1998-01/2010-12相关文章。纳入冠状动脉支架置入后炎症因子水平变化方面的文献,排除重复研究或Mata分析类文章。 结果：冠状动脉内支架置入有可能会引起冠状动脉血管的损伤,促进体内细胞释放炎症因子,通过炎症因子和细胞因子的表达,能很好的反映支架置入后局部血管损伤程度和炎症水平。药物涂层支架能够显著降低支架置入后再狭窄发生率及靶病变再次血运重建率,但显著增加晚期支架血栓形成。通过凝血系统各因子水平评估,药物涂层支架置入前后充分地抗血小板治疗能够降低支架血栓的发生。 结论：支架置入体内后与血液及血管壁接触可产生炎症和致敏反应,因此支架置入前后应充分控制炎症状态和抗凝血治疗。     

表面磁性膜医用316L不锈钢支架对兔髂动脉内膜增殖的影响

目的 研究表面磁性膜医用316L不锈钢支架对新西兰大白兔髂动脉新生内膜增殖的影响.方法 通过动物体内支架植入,采用定量冠脉造影、光学显微镜图像技术观察不同支架对新生内膜增殖和再狭窄的影响.结果 与普通裸支架相比,表面磁性膜支架可以抑制支架植入后的新生内膜增殖和再狭窄,植入3月后应用表面磁性膜支架和普通裸支架的管腔面积分别为(2.78±0.40)mm2和(2.07±0.62)mm2,再狭窄率分别为3.3%和16.7%,且可能与磁场强度相关.结论 表面磁性膜支架对经皮冠状动脉介入治疗术后的再狭窄可能具有防治作用.     

Approaches for prevention of restenosis

Coronary artery disease is characterized by a narrowing (stenosis) of the arteries that supply blood to the tissue of the heart. Continued restriction of blood flow manifests itself as angina and ultimately myocardial infarction (heart attack) for the patient. Heart bypass was once the only treatment for this condition, but over the years percutaneous coronary intervention (PCI) has become an increasingly attractive alternative to medical therapy and surgical revascularization for the treatment of coronary artery disease. A vascular stent is a medical device designed to serve as a temporary or permanent internal scaffold, to maintain or increase the lumen of a blood vessel. Metallic coronary stents were first introduced to prevent arterial dissections and to eliminate vessel recoil and intimal hyperplasia associated with PCI. Further advancement in the treatment of coronary artery disease is the development of drug-eluting stents that dramatically reduce the incidence of in-stent restenosis to less than 5%. Local drug delivery offers the advantages of allowing a relatively high local concentration of drug at the treatment site while minimizing systemic toxic effect. This review describes approaches for prevention of restenosis. It focuses on drugs for prevention of restenosis, bare metal stents, and drug-eluting stents. It also describes recent advances in bioresorbable stents. One of the chapters is dedicated to our novel composite bioresorbable drug-eluting fibers, designed to be used as basic elements in drug-eluting stents.     

The consequences of the mechanical environment of peripheral arteries for nitinol stenting

The use of stents in peripheral arteries has not been as successful as in coronary arteries, with high rates of restenosis and stent fracture common. Normal joint flexion induces a range of forces on the arteries, which has an unknown effect on the outcomes of stenting. The objective of this study is to determine how physiological levels of vessel bending and compression following stent implantation will influence the magnitude of stent stresses and hence the risks of fatigue fracture. A further objective is to compare how this mechanical environment will influence arterial stresses following implantation of either stainless steel or nitinol stents. To this end, models of both nitinol and stainless steel stents deployed in peripheral arteries were created, with appropriate loading conditions applied. At high levels of bending and compression, the strain amplitude threshold value for fatigue failure is exceeded for nitinol stents. Bending was predicted to induce high stresses in the artery following stenting, with higher arterial stresses predicted following implantation of a stainless steel stent compared to a nitinol stent. Both bending and compression may contribute to stent fracture by increasing the strain amplitude within the stent, with the dominant factor dependant on location within the arterial tree. For the specific stent types investigated in this study, the model predictions suggest that compression is the dominant mechanical factor in terms of stent fatigue in the femoral arteries, whereas bending is the most significant factor in the popliteal artery. To increase fatigue life and reduce arterial injury, location specific stent designs are required for peripheral arteries.     

Angiographic follow-up after placement of a self-expanding coronary-artery stent

BACKGROUND. The placement of stents in coronary arteries after coronary angioplasty has been investigated as a way of treating abrupt coronary-artery occlusion related to the angioplasty and of reducing the late intimal hyperplasia responsible for gradual restenosis of the dilated lesion. METHODS. From March 1986 to January 1988, we implanted 117 self-expanding, stainless-steel endovascular stents (Wallstent) in the native coronary arteries (94 stents) or saphenous-vein bypass grafts (23 stents) of 105 patients. Angiograms were obtained immediately before and after placement of the stent and at follow-up at least one month later (unless symptoms required angiography sooner). The mortality after one year was 7.6 percent (8 patients). Follow-up angiograms (after a mean [+/- SD] of 5.7 +/- 4.4 months) were obtained in 95 patients with 105 stents and were analyzed quantitatively by a computer-assisted system of cardiovascular angiographic analysis. The 10 patients without follow-up angiograms included 4 who died. RESULTS. Complete occlusion occurred in 27 stents in 25 patients (24 percent); 21 occlusions were documented within the first 14 days after implantation. Overall, immediately after placement of the stent there was a significant increase in the minimal luminal diameter and a significant decrease in the percentage of the diameter with stenosis (changing from a mean [+/- SD] of 1.88 +/- 0.43 to 2.48 +/- 0.51 mm and from 37 +/- 12 to 21 +/- 10 percent, respectively; P less than 0.0001). Later, however, there was a significant decrease in the minimal luminal diameter and a significant increase in the stenosis of the segment with the stent (1.68 +/- 1.78 mm and 48 +/- 34 percent at follow-up). Significant restenosis, as indicated by a reduction of 0.72 mm in the minimal luminal diameter or by an increase in the percentage of stenosis to greater than or equal to 50 percent, occurred in 32 percent and 14 percent of patent stents, respectively. CONCLUSIONS. Early occlusion remains an important limitation of this coronary-artery stent. Even when the early effects are beneficial, there are frequently late occlusions or restenosis. The place of this form of treatment for coronary artery disease remains to be determined.     

Intravascular stents to prevent occlusion and restenosis after transluminal angioplasty

Occlusion and restenosis are the most common reasons that transluminal balloon angioplasty may fail to provide long-term benefit. An intravascular mechanical support was therefore developed with the aim of preventing restenosis and sudden closure of diseased arteries after angioplasty. The endoprosthesis consists of a self-expandable stainless-steel mesh that can be implanted nonsurgically in the coronary or peripheral arteries. Experiments in animals showed complete intimal coverage within weeks and no late thrombosis during a follow-up period of up to one year. We performed 10 implantations in 6 patients for iliac or femoral arterial disease; 24 coronary-artery stents were implanted in 19 patients who presented with coronary-artery restenoses (n = 17) or abrupt closure (n = 4) after transluminal angioplasty or deterioration of coronary-bypass grafts (n = 3). We observed three complications in the group with coronary disease. One thrombotic occlusion of a stent resulted in asymptomatic closure, a second acute thrombosis was managed successfully with thrombolysis, and one patient died after bypass surgery for a suspected but unfound occlusion. Follow-up in the patients has continued for nine months without evidence of any further restenoses within the stented segments. Our preliminary experience suggests that this vascular endoprosthesis may offer a useful way to prevent occlusion and restenosis after transluminal angioplasty. Long-term follow-up will be required to validate the early success of this procedure.     

药物洗脱冠状动脉支架系统动物实验研究

目的通过观察在猪动脉中置人心畅可降解聚合物涂层药物洗脱冠状动脉支架（天津百畅公司开发）及对照组支架后的植入后管腔丢失、内皮化、炎症反应、损伤及血栓形成情况来评价国产可降解聚合物涂层药物洗脱支架临床应用的可行性。方法将2种共60枚支架分别置入30头猪冠状动脉的前降支、回旋支以及右冠状动脉。支架植入后的2,5,12,25周,将不同数量的猪处死行组织形态学检查,观察炎症、血栓形成情况和内皮化评价。结果支架置入术后的冠脉通畅,无明显狭窄;支架贴血管内壁良好,血管内腔表面光滑;2种支架均无血栓形成,心畅可降解聚合物涂层药物洗脱支架炎症反应及内皮化与对照组无明显差异,其管腔丢失较对照组轻或无明显差异。结论实验提示心畅可降解聚合物涂层药物洗脱支架置入后有良好的血液相容性,生物性能稳定,支架内表面迅速内皮化,血管有良好的开通率。说明可降解聚合物涂层药物洗脱支架是安全、有效的。     

A comparison of stent-induced stenosis in coronary and peripheral arteries

BACKGROUND AND OBJECTIVES: Restenosis is a complication of interventional procedures such as angioplasty and stenting, often limiting the success of these procedures. Knowledge regarding the relative behaviour of different arteries after these procedures is limited, despite the extensive use of different vascular models. Although the results from studies using different vessels are analysed to predict the behaviour of coronary arteries and other vasculature, direct controlled comparisons between different arteries are necessary for a better understanding of the differential response to restenosis. METHODS: This study examines the response to stenting in coronary and internal iliac arteries as characterised by intimal hyperplasia and restenosis. In a swine model of in-stent stenosis, coronary arteries exhibited higher levels of intimal hyperplasia and per cent stenosis than internal iliac arteries. RESULTS: After normalisation for injury score, coronary arteries were found to undergo 47% more intimal hyperplasia (p<0.05), whereas per cent stenosis normalised for injury score tended to be higher (p = 0.01). Other measurements reflecting post-stenting intimal hyperplasia (maximal intimal thickness, medial area) did not exhibit significant differences between the artery groups. CONCLUSIONS: These results show that coronary vessels are more prone to develop significant intimal hyperplasia and subsequent restenosis than internal iliac vessels. A better insight into how different arteries and arterial components behave is important in understanding and developing newer and better therapeutic measures for restenosis.