静脉桥血管外支架的研究

冠状动脉旁路移植手术(CABG)后,自体大隐静脉桥的再狭窄是亟需解决的问题。血管外支架是预防静脉桥再狭窄的一种可行办法。本文综述了多年来静脉桥血管外支架在材料方面、作用机制、临床应用研究等文献以反映静脉桥血管外支架的研究进展。     

血管外PHA生物支架抑制移植静脉狭窄的应用价值

目的观察血管外聚羟基烷酸酯（PHA）可降解生物支架对移植静脉内膜增生的影响,探讨其应用价值及可能的作用机制,为临床治疗血管再狭窄提供新方法和理论依据。方法采用袖套法将大鼠自体颈外静脉移植入同侧颈动脉,根据有无支架干预分为对照组和支架组。术后1、2、4周分别切除移植静脉,应用病理形态学方法检测移植静脉外膜新生血管密度,计算机图像分析系统测量和计算内膜厚度。免疫组化法检测其增殖细胞核抗原（PCNA）指数、移植静脉局部核转录因子-κB（NF-κB）和转化生长因子-β1（TGF—β1）的表达。结果支架组移植静脉内膜增生程度、PCNA指数、NF-κB和TGF—β1的表达均低于对照组（P〈0．05）,移植静脉外膜新生血管密度明显高于对照组（P〈0．05）。结论血管外PHA可降解生物支架防治移植静脉狭窄有一定作用,其抑制移植静脉狭窄的机制可能与其下调NF—κB、TGF—β1的表达及促进移植静脉外膜血管生成有关。     

VEGF在血管外支架预防移植静脉再狭窄中的作用

冠状动脉旁路移植术后,自体大隐静脉桥的再狭窄是急需解决的问题,应用血管外支架是预防再狭窄的一种可行办法.血管内皮生长因子(VEGF)是一种特异性地直接作用于血管内皮细胞,促进新生血管形成,并能增强毛细血管通透性的细胞因子.本文就近年来VEGF在静脉桥血管外支架预防移植静脉再狭窄中的作用作一综述.     

静脉桥动脉化后桥血管重塑的实验研究

目的探讨静脉动脉化（AVG）对静脉桥血管结构重塑的影响。方法将30只SD大鼠随机分为实验组和对照组。实验组采用改良cuff法构建颈AVG模型,对照组仅模拟手术环境,切开和缝合皮肤、分离动静脉,未进行AVG。分别于术后1、2、4周取出静脉桥及对照组颈静脉,进行形态学分析,研究桥血管内膜和中膜的增生变化。结果 2组模型均无动物死亡。4周时实验组1只闭塞,通畅率93.3%。实验组1、2、4周时内膜及中膜均较对照组增厚（P〈0.05或〈0.01）。结论 AVG使静脉桥血管内膜及中膜增生,加快了静脉桥血管的结构重塑。     

可降解性PDS血管外支架抑制移植静脉内膜增生的动物实验观察

24只新西兰大白兔随机分为对照组和实验组,各12只。对照组单纯行颈外静脉移植,实验组同时移植可降解性聚对二氧环己酮（PDS）血管外支架。术后4周取出移植静脉,测量其内膜、中膜的厚度和面积,检测增殖细胞核抗原（PCNA）．计算细胞增殖率。结果显示,实验组PDS血管外支架与移植静脉壁之间形成了富含毛细血管的新生外膜,移植静脉中膜及内膜厚度、面积皆小于对照组（P均〈0．05）;其细胞增殖率为22％±11％,低于对照组的37％±15％（P〈0．05）。认为可降解性PDS血管外支架具有良好的组织相容性,早期可以明显抑制移植静脉内膜和中膜增生。     

血流剪切力对静脉桥血管再狭窄影响的研究进展

正大隐静脉因其易得、长度足够且较为匹配等特点是冠状动脉搭桥术中广泛使用的血管材料,然而静脉桥具有较高的再狭窄率,术后10年约50%的静脉桥血管发生狭窄或闭塞。造成静脉桥血管再狭窄的因素较多,如获取静脉血管时的操作损伤、缺血再灌注,早期血管内血栓形成,内膜细胞的增殖、血小板及白细胞的黏附及平滑肌细胞的增生等。静脉桥     

预防静脉桥再狭窄的基因治疗研究现状

在外科治疗动脉狭窄或闭塞性疾病中,应用静脉移植使血管重建是一种常用的方法,其中,在冠状动脉疾病中应用较为广泛,尤其是应用自体大隐静脉进行冠状动脉旁路移植手术。短期内其效果非常有效,但远期通畅率欠佳,尽管有一定的预防方法,但是效果不太理想,而基因治疗作为其中的一项,成为一个潜在的治疗选择。基因治疗可以通过减少血栓形成、血管内膜增生、动脉粥样硬化进而改善桥血管通畅率,本文我们将对预防静脉桥再狭窄的基因治疗做一综述。     

冠状动脉旁路移植术后静脉桥血管通畅率的研究进展

<正>冠状动脉旁路移植术(coronary artery bypass grafting,CABG)是现今治疗冠心病最有效的手术方法之一[1],术后5~10年内约25%~50%的桥血管会发生再狭窄或者闭塞[2],评价CABG疗效的最主要指标之一是桥血管近、远期的通畅率。国内外CABG采用最多的移植血管是乳内动脉(internal mammary artery,IMA)和大隐静脉(saphenous vein,SV)。由于IMA长度受限以及冠心病患者大多为多支冠状动脉病变,所以自体SV仍然是CABG术中最常用的桥血管移植材料[3]。如何提高静脉桥血管的远期通畅率已经成为CABG术后的一个研究热点。本文对近年来有关静脉桥血     

冠状动脉旁路移植术后静脉桥血管阻塞病变的经皮介入治疗进展

慢性完全闭塞性冠状动脉（冠脉）病变、分叉病变、支架内再狭窄、冠脉旁路移植术（CABG）后静脉桥血管（saphenous vein bypass graft，SVBG）阻塞的介入治疗，是当今经皮冠脉介入治疗的几个主要难题。伴随CABG术后再次心肌缺血患的增多，已有国内学关注到SVBG病变的介入治疗问题。     

Drug-eluting stents versus bare metal stents for narrowing in saphenous vein grafts

Conflicting data exist regarding an advantage of drug-eluting stents (DES) over bare metal stents (BMS) in catheter-based treatment of saphenous vein graft (SVG) stenoses. This study was undertaken to compare the efficacy of these modalities in that lesion subset. The DES group consisted of 138 cases with 183 lesions (sirolimus-eluting stents, n = 117; paclitaxel-eluting stents, n = 66) and the BMS group consisted of 344 cases with 478 lesions that were followed to 1 year. We examined a composite end point that comprised death, Q-wave myocardial infarction, and target lesion revascularization. More BMS were deployed per patient (p <0.001) and the diameters of BMS deployed was significantly greater (p <0.001). Peak postprocedure values of creatine kinase-MB (p = 0.003) and troponin I (p = 0.05) were higher in BMS. At 1 year there was no significant superiority of DES over BMS with regard to hard end points (death and Q-wave myocardial infarction). In conclusion, this study indicates that both DES and BMS for SVG disease provide acceptably safe and efficacious results, but unlike the case in native coronary arteries, DES use does not reduce the frequency of the need for repeat revascularization.     

New treatment approach for chronic total occlusions of saphenous vein grafts: Thrombolysis and intravascular stents

Balloon dilation of saphenous vein graft (SVG) occlusions has a lower success rate than angioplasty of native coronary arteries. To improve this outcome, a new therapy for chronic total SVG occlusions was developed. In three aortocoronary bypass graft patients with class III-IV angina and chronic occlusion of the SVGs to the left anterior descending artery (age of occlusions: 2–24 wk, age of graft 1–13 yr), standard recanalization was achieved with a guide wire and intracoronary urokinase infusion (0.5–1.0 million unit bolus followed by 100,000 IU/hr for 11–24 hr; mean infusion time: 19.7 hr). In each patient, a residual focal stenosis (average 82.5%) was successfully dilated and stented (single 4.0 mm Pal-maz-Schatz in two patients and a 3.5 mm Strecker stent in the other). All patients had complete relief of symptoms and no sequelae. During a mean 7.7 mon follow-up, 6-mon arteriographic evaluation in two patients showed minimal intra-stent narrowing (26% and 34%). In the Strecker stent patient, the device proved too small for the vein graft, leading to an 89% stent stenosis found on follow-up arteriography at 5 mon. The stent was redilated successfully with a 5% residual narrowing. After urokinase recanalization of chronic total SVG occlusions, intravascular stents may improve the long-term results seen with conventional SVG angioplasty. © 1993 Wiley-Liss, Inc.     

Treatment of totally occluded saphenous vein grafts using self-expanding stents

Patients with saphenous vein graft (SVG) disease represent an increasing proportion of those referred for percutaneous coronary intervention. The success of treatment of occluded SVG with percutaneous intervention has been limited by frequent occurrence of no-reflow phenomenon. Use of self-expanding stents with low pressure pre- and post-dilation may improve success by limiting embolism of atherothrombotic debris. The self-expanding stents provide a meshed design that helps to trap the atherothrombotic debris between the vessel wall and stent struts. Results with two patients are described to illustrate the proposed technique that appears to limit no-reflow during and immediately after the procedure. Adjunctive treatment with a GP IIb-IIIa inhibitor is likely to be of benefit as well. Additional studies are required to demonstrate definitively the potential benefits of this approach.     

A randomized trial of polytetrafluoroethylene-membrane-covered stents compared with conventional stents in aortocoronary saphenous vein grafts

We compared a conventional stent (Jostent Flex, Jomed GmbH, Rangendingen, Germany) with a polytetrafluoroethylene (PTFE)-membrane-covered stent (Jostent Stentgraft) in patients undergoing intervention of a stenosis in an obstructed vein graft.The use of stents improved results of percutaneous revascularization of obstructed vein grafts, but did not demonstrate the reduced elevated restenosis rate. In addition, long-term clinical event rate is still high compared with intervention in native vessels. Observational studies suggested that stents covered with a PTFE membrane might be associated with a low complication and restenosis rate in venous bypass grafts.This prospective multicenter study included a total of 211 patients who were randomly assigned to receive either a Flex stent or Stentgraft. The primary end point was binary restenosis rate at six months by core lab quantitative coronary angiography.Acute success and procedural events were comparable between the two groups. Restenosis rate was not significantly different between the Flex (20%) and the Stentgraft (29%) groups (p = 0.15), although there was a nonsignificant trend toward a higher late occlusion rate in the Stentgraft group (7% vs. 16%, p = 0.069) at follow-up. Likewise, after a mean observation period of 14 months, cumulative event rates (death, myocardial infarction, or target lesion revascularization) were comparable in the two groups (31% vs. 31%, p = 0.93).This controlled trial does not indicate a superiority of the PTFE-membrane-covered Stentgraft compared with a conventional stent with respect to acute results, restenosis, or clinical event rates.     

Self expanding stents for the management of aorto-ostial stenoses in saphenous vein bypass grafts.

OBJECTIVE--To assess the early and follow up results of implantation of a self expanding stent in aorto-ostial stenoses of vein grafts. DESIGN--Prospective, non-randomised, observational study. SETTING--Tertiary referral centre for cardiac diseases. PATIENTS--Nineteen patients with ostial stenoses of saphenous vein grafts. MAIN OUTCOME MEASURES AND RESULTS--Stents were successfully deployed in all 19 patients with satisfactory angiographic results. In one patient this required two attempts. There were no deaths and no major procedural complications related to ostial stenting. Before discharge two (11%) patients had thrombosis of the ostial stent; one patient had a Q wave myocardial infarction. Femoral artery bleeding occurred in three (16%) patients. Angiographic follow up was performed in 18 patients at a mean of seven months. Restenosis within the ostial stent was detected in three (16%) patients. Twelve (63%) patients had an improved functional status at a mean follow up of nine months. One patient died suddenly at three months. Three (16%) patients required additional revascularisation procedures because of symptoms caused by restenosis within the ostial stent during follow up. CONCLUSIONS--Intracoronary stenting is an attractive treatment for the management of patients with vein graft ostial stenoses.     

Implantation of half palmaz-schatz stents in short aorto-ostial lesions of saphenous vein grafts

Two cases are presented in which a half Palmaz-Schatz stent was implanted in a short lesion located in the ostium of a saphenous vein graft. Aorto-ostial stenoses are a technical challenge for balloon angioplasty and stenting. Short stents may offer several advantages as regards deployment, positioning, thrombogenicity, and restenosis. © 1993 Wiley-Liss, Inc.