不同支架置入术后猪冠状动脉内膜增生与血管损伤程度的关系

目的:制作猪冠状动脉支架置入术模型,对行不同类型支架留置术后内膜的增生与血管损伤情况进行研究。方法:把Co il支架及T ubu lar支架分别置入9头猪共36支冠脉血管内,使用血管内超声(IVU S),免疫组织学等方法观察以下项目,(1)第28 d时的内膜肥厚面积;(2)支架对血管壁的损伤程度。结果:(1)用IVU S评价支架置入第28 d时的支架面积,血管内腔面积:T ubu lar支架的明显高于Co il支架的,[分别为(7.74±0.42)mm2∶(6.75±0.56)mm2,P<0.001);(5.27±0.53)mm2∶(4.02±0.76)mm2,P<0.001];(2)用免疫组织学的方法分析支架对血管壁的损伤程度:T ubu lar支架小于Co il支架的[(1.69±0.32)mm2∶(2.00±0.40)mm2,P<0.05];(3)两组支架的损伤程度与内膜肥厚的长度呈良好的正相关(r2分别为0.8198,0.8749)。结论:支架术后再狭窄与血管损伤及冠状动脉内膜增生的厚度有关,减少血管损伤是预防再狭窄的关键之一。     

光学相干断层成像比较猪冠状动脉西罗莫司洗脱支架与佐他莫司洗脱支架置入后早期新生内膜覆盖情况

目的应用光学相干断层成像(OCT)比较西罗莫司洗脱支架(SES)与佐他莫司洗脱支架(ZES)置入后1月内新生内膜覆盖情况。方法 18只中华小型猪平均分为3组,每只猪分别在前降支和右冠状动脉随机置入SES和ZES支架各一枚,3组实验动物分别在第7天、14天、28天进行OCT检查,测量新生内膜厚度、支架内面积、管腔内面积、新生内膜面积、面积狭窄百分比和新生内膜覆盖率,比较ZES与SES置入后1月内新生内膜覆盖情况。结果 OCT测量结果显示,支架置入7天和14天时,ZES与SES两种支架丝表面新生内膜厚度和新生内膜覆盖率均存在显著统计学差异(P<0.001)。同样支架术后28天时ZES与SES支架丝表面新生内膜厚度存在显著统计学差异(244.3±282.3μmvs136.3±91.1μm,P<0.001),新生内膜覆盖率存在显著差异(94.88%±2.93%vs90.96%±4.35%,P=0.008)。结论在支架置入后1个月内,ZES与SES比较新生内膜增生更显著,支架丝表面新生内膜覆盖率更高。     

国产与进口西罗莫司洗脱支架置入后血管内超声随访的对比

目的 利用血管内超声对比观察国产与进口西罗莫司洗脱支架对冠心病患者支架术后新生内膜增生的抑制作用.方法 2003年5月至2007年3月,对215例冠心病患者(317处病变)置入西罗莫司洗脱支架,并在术后1年行冠状动脉造影和血管内超声(IVUS)检查.其中Firebird组108例患者(147处病变)置入国产西罗莫司洗脱支架(Firebird支架),Cypher组107例患者(138处病变)置入进121西罗莫司洗脱支架(Cypher支架).结果 两组患者一般临床情况差异无统计学意义.两组靶病变部位、病变长度、狭窄程度及病变类型差异均无统计学意义,但Firebird组术后最小管腔直径大于Cypher组[(2.88±0.43)mm比(2.78±0.33)mm,P＜0.05].随访定量冠状动脉造影分析显示,Firebird组与Cypher组支架内晚期管腔丢失[(0.17±0.29)mm比(0.16±0.27)mm,P＞0.05]和节段内晚期管腔丢失[(0.18±0.36)mm比(0.20±0.32)mm,P＞0.05]差异均无统计学意义.IVUS分析显示,与Cypher组比较,尽管Firebird组支架面积[(6.99±2.25)mm~2比(6.46±1.71)mm~2,P＜0.05]、管腔面积[(6.89±2.30)nm~2比(6.36±1.73)mm~2,P＜0.05]、支架体积[(162.5±68.9)mm~3比(140.8±57.9)mm~3,P＜0.01]、管腔体积[(160.4±69.5)mm~3比(138.6±57.6)mm~3,P＜0.01]及最小支架面积[(5.40±1.85)mm~2比(4.92±1.43)mm~2,P＜0.05]均较大,但两组的内膜增生容积[(2.09±5.46)mm~3比(2.23±6.50)mm~3,P＞0.05]和内膜增生容积百分数[(1.68±5.84)%比(1.59±4.10)%,P＞0.05]差异均无统计学意义.结论 Firebird支架置人后再狭窄的发生率较低,抑制内膜增生作用与Cypher支架相似.     

新型生物可降解聚合物雷帕霉素靶向洗脱支架预防支架内狭窄的动物实验研究

目的:评价新型的生物可降解聚合物雷帕霉素靶向洗脱支架—Firehawk在小型猪冠状动脉模型预防支架内狭窄的疗效。方法:将Firehawk支架(Firehawk组,n=10)和采用永久聚合物涂层雷帕霉素洗脱支架Firebird 2(Firebird 2组,n=8)置入健康小型猪冠状动脉。术后4周时测定两组支架血管段的平均内膜厚度、新生内膜面积、面积狭窄百分比等参数,以比较其内膜增生的情况。结果:术后4周,Firehawk组和Firebird 2组平均内膜厚度分别为(0.15±0.10)mm和(0.14±0.06)mm,新生内膜面积分别为(1.12±0.57)mm2和(1.04±0.36)mm2,面积狭窄百分比分别为(24.58±14.85)%和(26.80±10.64)%,差异均无统计学意义(P均>0.05)。两组均无支架内狭窄发生。结论:Firehawk支架可有效抑制支架置入后4周时的内膜增生,预防冠状动脉实验性支架内狭窄,效果与传统的永久聚合物涂层药物洗脱支架相当。长期效果有待进一步观察。     

川芎嗪药物涂层支架预防猪冠状动脉再狭窄的实验研究

目的 探讨川芎嗪药物涂层支架(TES)预防冠状动脉再狭窄的作用机制及其有效性.方法 TES为金属管状支架经喷涂川芎嗪单体制成(含川芎嗪200μg).采用随机、双盲实验在14只小型猪的冠状动脉左前降支分别置入TES及金属裸支架(BMS)(实验组7只,对照组7只).支架置入前后均行定量冠状动脉造影(QCA)及血管内超声(IVUS)检查.术后第28天随访行QCA及ⅣUS观察支架内膜增殖及血栓形成情况.实验终点处死动物,获取支架置入段血管及支架前后5 cm处组织行病理学及免疫组化检查.结果 14只动物均成功置入支架,4只动物因手术意外死亡未列入统计.5只动物于左前降支置入TES,5只动物置入BMs.术后第28天随访,QCA检查支架段血管直径狭窄百分比两组分别为实验组(10.0±2.1)%和对照组(60.2±23.5)%(P=0.01).IVUS检查显示,两组支架内面积相似,均未见血栓形成.对照组内弹力膜面积较实验组明显减小(P=0.021),而新生内膜面积明显增大(P=0.004).术后处死动物组织形态学检查显示两组血管损伤评分和支架内面积相近(P>0.05),均无明显的炎症反应,但实验组管腔面积[(4.34±0.93)mm2]较对照组[(1.29±1.02)mm2]明显增加(P=0.011),新生内膜面积[(1.51±0.45)mm2]较对照组[(4.60±1.39)mm2]明显减少(P=0.004).组织病理学检查提示所有支架置入节段均完全内皮化,实验组增殖细胞核抗原染色阳性细胞核明显减少,凋亡细胞较对照组增多.结论 川芎嗪药物涂层支架能有效抑制血管内膜增殖及血栓形成,减少支架内再狭窄.     

二烯丙基三硫化物包被支架预防冠状动脉内膜损伤后再狭窄的实验研究

目的 探讨不同剂量二烯丙基三硫化物(diallyl trisulfide,DT)包被支架对犬冠状动脉支架置入术后再狭窄的预防作用。方法 制作蛋白涂层的DT包被支架,其剂量分别为0 μg(对照组)、60 μg(小剂量组)、130μg(中剂量组)和210μg(大剂量组)。11只杂种犬,其左冠状动脉分别置入过大的单纯蛋白包被支架和DT包被支架。术前、术后即刻及术后6个月冠状动脉造影观察动脉狭窄程度;术后6个月取出血管组织,经Elastic-van Gieson染色,进行形态学观察,通过图像分析系统分析测定管腔面积、内弹力板包绕面积,并计算内膜面积和面积狭窄率。结果 各组平均损伤积分相似。大剂量组平均内膜厚度[(0.18±0.03)mm]小于中剂量组[(0.24±0.03)mm,P=0.008]、小剂量组[(0.46±0.05)mm,P<0.001]和对照组[(0.49±0.06)mm,P<0.001];大、中剂量组内膜面积相似[(2.50±0.49)mm2比(2.78±0.78)mm2,P>0.05],但显著小于小剂量组[(4.65±0.58)mm2,P<0.001]和对照组[(4.87±0.80)mm2,P<0.001]。大、中剂量组的面积狭窄率相似[(30.04±5.43)％比(34.25±7.41)％,P>0.05],但显著小于小剂量组[(53.10±1.93)％,P<0.001]和对照组[(54.62±6.82)％,P<0.001]。结论 DT包被支架呈剂量依赖性抑制新生内膜增生,6个月内预防再狭窄疗效明显。     

西罗莫司洗脱支架与紫杉醇洗脱支架抑制血管内膜增生的血管内超声比较

目的:利用血管内超声(IVUS)方法比较西罗莫司洗脱支架(CypherTM)与紫杉醇洗脱支架(TaxusTM)对冠心病患者新生内膜增生的抑制作用.方法:自2003-05至2007-04,167例冠心病患者(227处病变)行药物洗脱支架术,并在术后1年行冠状动脉造影和IVUS检查.其中107例患者(138处病变)置入CypherTM支架(Cypher组),60例患者(89处病变)置入TaxusTM支架(Taxus组).结果:两组患者基础临床情况及病变特征相似.造影结果分析显示,Cypher组支架内晚期管腔丢失、节段内晚期管腔丢失明显小于Taxos组[分别为(0.16±0.27)mm比(0.43±0.51)mm,P<0.01;和(0.20±0.32)mm比(0.38±0.33)mm,P=0.01],而两组近端和远端参考血管晚期管腔丢失差异无统计学意义[分别为(0.13±0.29)mm比(0.15±0.32)mm,P=0.689;和(0.08±0.12)mm比(0.09±0.16)mm,P=00500].IVUS分析显示,两组平均支架面积、平均管腔面积、最小支架面积、平均支架体积、平均管腔体积差异均无统计学意义,而Cypher组与Taxus组比平均内膜增生面积[(0.33±0.45)mm2比(1.29±1.26)mm2]、平均内膜增生面积百分数[(5.42±7.33)%比(17.38±13.75)%]、内膜增生最大面积百分数[(10.13±13.85)%比(31.56±20.99)%]、平均内膜增生容积[(2.23±6.50)mm3比(13.43±18.59)mm3]和平均内膜增生容积百分数[(1.59±4.10)%比(8.62±9.90)%],Cypher组均较Taxus组明显减小(P<0.0001),差异均有统计学意义.结论:CypherTM支架治疗冠心病一年再狭窄发生率较低,与TzxusTM支架相比,抑制内膜增生作用更显著.     

雷公藤内酯醇涂层支架对猪冠状动脉内皮结构和再狭窄的影响

目的观察雷公藤内酯醇涂层支架（triptolide）置入猪冠状动脉后,血管内膜增殖过程中NF-κB、ki67表达的变化,探讨该药物支架对血管内皮的影响。方法将8只猪进行冠状动脉支架置入术,将雷公藤内酯醇涂层支架和裸支架组对照,置入前降支、回旋支、右冠脉近端。术后12周处死动物,采用光镜观察内膜增生情况,扫描电镜观察内皮修复情况,免疫组织化学法检测平滑肌细胞NF-κB、ki67表达。结果术后12周,triptolide组血管内膜增生[(内膜厚度（0.12±0.05）mm]、内膜面积[（1.17±0.25）mm2]明显小于对照组[内膜厚度[（0.35±0.11）mm,P<0.01],内膜面积[（1.81±0.36）mm2,P<0.05];电镜显示血管内膜表面的内皮细胞较对照组分布更紧密,排列更整齐,覆盖更完整;药物组NF-κB、ki67表达量显著低于对照组。结论雷公藤内酯醇涂层支架可抑制猪冠状动脉平滑肌细胞增殖,有效控制局部炎性活动,抑制内膜增殖。     

抗CD34抗体优化雷帕霉素洗脱支架疗效的实验研究

目的 评价抗CD34抗体对雷帕霉素洗脱支架早期再内皮化以及远期抗再狭窄的影响.方法 将裸金属支架(BMS)、雷帕霉素洗脱支架(SES)和抗CD34抗体与雷帕霉素洗脱联合支架(ASES)随机置入到22头中华小型猪的冠状动脉内(共置入15枚BMS、17枚SES和16枚ASES).10头中华小型猪在置入支架(共置入6枚BMS、7枚SES和7枚ASES)后2周,另外12头中华小型猪在置入支架(共置入9枚BMS、10枚SES和9枚ASES)后3个月,进行冠状动脉造影及冠状动脉内光学相干断层成像( OCT)检查,并在处死动物后对支架段冠状动脉进行病理组织学检查及扫描电镜观察.结果 (1)支架术后2周,冠状动脉造影、OCT图像及支架段冠状动脉的病理组织学的观察均未发现支架内血栓及小的附壁血栓.对OCT图像的分析显示,ASES新生内膜覆盖率显著高于SES[ (55.56±35.27)％比(41.82±23.28)％,P＜0.05];ASES平均内膜覆盖厚度不但显著高于SES[(89.0±5.0)μm比(32.0±4.9) μm,P＜0.01],而且显著高于BMS[( 89.0±5.0) μ,m比(44.0±7.2)μm,P＜0.01].病理组织学观察及扫描电镜观察显示,ASES和BMS新生内膜覆盖水平及质量均优于SES.(2)支架术后3个月,定量冠状动脉造影显示ASES晚期支架内管腔丢失显著低于BMS [(0.18±0.06)mm比(0.35±0.06)mm,P＜0.05];对OCT图像的分析显示,ASES和SES新生内膜增生百分比均显著低于BMS[ (34.75±2.64)％和(35.63±2.07)％比(48.28±3.25)％,均P＜0.01];组织病理学分析显示,ASES和SES面积再狭窄百分比均显著低于BMS组[(28.65±5.64)％和(29.33±6.07)％比(46.18±8.25)％,均P＜0.05].结论 将抗CD34抗体联合应用到雷帕霉素洗脱支架上能够显著抵消后者在支架术后2周对再内皮化的抑制作用,同时没有削弱雷帕霉素洗脱支架术后3个月的抗再狭窄效能.     

Mytrolimus药物洗脱支架预防支架内再狭窄的实验研究

目的评价新型聚烯烃类高分子化合物涂层携载雷帕霉素衍生物-Mytrolimus(CCI-779)洗脱支架在小型猪冠状动脉模型预防再狭窄的疗效。方法小型猪冠状动脉分别置入裸支架、单纯聚烯烃类高分子化合物涂层支架和Mytrolimus洗脱支架(160μg/18mm)。术后4周重复冠状动脉造影后处死动物,测定3组支架血管段的损伤指数、冠状动脉横截面积、管腔面积、支架上平均内膜厚度、支架间平均内膜厚度、新生内膜面积、面积再狭窄百分比,并作比较。结果裸支架组(置入支架数n=10)、单纯聚烯烃类高分子化合物涂层支架组(n=10)和Mytrolimus洗脱支架组(n=8)3组冠状动脉大小和血管损伤程度基本相同,术后4周,单纯聚烯烃类高分子化合物涂层组与裸支架比较多项参数差异均无统计学意义。Mytrolimus药物洗脱支架组和裸支架组的支架上内膜厚度分别为(0.18±0.08)mm和(0.33±0.25)mm(P<0.05);支架间内膜厚度分别为(0.14±0.05)mm和(0.28±0.23)mm(P<0.05);新生内膜面积分别为(1.09±0.24)mm2和(2.44±1.59)mm2(P<0.05)。上述多项参数在Mytroliums洗脱支架组均显著少于裸支架组。Mytrolimus组新生内膜面积比裸支架组少了55.33%,且Mytrolimus组无一例再狭窄。结论Mytrolimus洗脱支架在置入小型猪冠状动脉4周时可有效抑制内膜增生、预防冠状动脉实验性支架内再狭窄。     

雷帕霉素-缬沙坦复方药物洗释支架预防支架内再狭窄的实验研究

目的　探讨雷帕霉素 -缬纱坦复方药物洗释支架 (复方药物洗释支架 )对支架植入术后再狭窄的预防作用。方法　对 2 2只雄性新西兰白兔进行腹主动脉拉伤后分别植入复方药物洗释支架 (复方组 )和普通支架 (裸支架组 )各 11只。两组均在术后 8周行血管内超声检查和腹主动脉行造影检查。结果　支架部位血管腔面积裸支架组小于复方组 (P <0 0 1)、支架内增生内膜面积及内膜增生程度裸支架组大于复方组 (P <0 0 0 1)。结论　复方药物洗释支架在动物实验中具有明显预防支架内再狭窄的作用     

蛋白涂层支架携带质粒介导的一氧化氮 合酶基因预防冠状动脉球囊扩张后 再狭窄的实验研究

目的　为评价蛋白涂层金属支架携带质粒介导的诱导性一氧化氮合酶 (iNOS)基因局部转染血管壁 ,预防冠状动脉内血管成形术后再狭窄的效果。方法　金属支架涂层为胶联明胶制成。载体为去内毒素纯化pcDNA3。采用标准球囊导管技术 ,将吸附有质粒介导的人肝脏的iNOS基因(pcDNA3hepiNOS)涂层支架置入小型猪 (n =9)冠状动脉前降支中段 ,以相同方法置入单纯蛋白涂层支架做为对照组 (n =9) ,支架与血管直径之比为 1.1～ 1.3:1。结果　在支架置入后 7d ,RT PCR检测和免疫组织化学染色 ,证实在pcDNA3hepiNOS转染的血管段有iNOSmRNA的表达和iNOS蛋白生成 ,而远离器官则无基因的表达。 3个月时冠状动脉造影显示 :转染pcDNA3hepiNOS组 (n =5 )无再狭窄发生 ,而对照组均发生显著的再狭窄。组织病理学形态分析结果显示 :pcDNA3hepiNOS组新生内膜面积 (1.7± 0 .8)mm2 、平均百分狭窄面积 (2 6 .5± 7.5 ) %、平均管腔狭窄百分数 (4 1.2± 16 .5 ) % ,均较对照组小 ,对照组分别为 (2 .8± 0 .8)mm2 ,P <0 .0 5 ;(94.2± 14.3) % ,P <0 .0 0 1;(88.0± 16 .6 ) % ,P <0 .0 0 1;比较内膜面积 /中膜面积比值 (I/M)治疗组较对照组减少了 5 9.8%。结论　在小型猪模型使用蛋白涂层支架携带纯化质粒介导的iNOS基因可直接导入血管     

国产西罗莫司洗脱支架与紫杉醇洗脱支架抑制血管内膜增生的血管内超声比较研究

目的利用血管内超声（IVUS）方法比较国产西罗莫司洗脱支架（Firebird^TM）与紫杉醇洗脱支架（Taxus^TM）对冠心病患者新生内膜增生的抑制作用。方法自2003年5月至2007年6月,203例冠心病患者（283处病变）行药物洗脱支架术并在术后1年行冠状动脉造影和血管内超声（IVUS）检查。其中136例患者（185处病变）置入Firebird^TM支架（Firebird组）,67例患者（98处病变）置入TaxusTM支架（Taxus组）。结果203例患者（283处病变）中168例患者（236处病变）接受了一年随访造影和血管内超声检查,其中Firebird组108例患者（147处病变）,Taxus组60例患者（89处病变）。两组患者基础临床情况及造影特征相似。Firebird组支架内晚期管腔丢失（0.17±0.29mm比0.43±0.51mm,P〈0.0001）和节段内晚期管腔丢失（0.18±0.36mm比0.38±0.33mm,P=0.003）明显小于Taxus组,而两组近端参考血管晚期管腔丢失（0.11±0.27mm比0.15±0.32mm,P=0.321）和远端参考血管晚期管腔丢失（0.08±0.10mm比0.09±0.16mm,P=0.483）差异并无统计学意义。IVUS分析显示,两组间平均支架面积、平均管腔面积、最小支架面积、平均支架体积、平均管腔体积比较,差异均无统计学意义。但Firebird组平均内膜增生面积（0.35±0.58mm^2比1.29±1.26mm^2,P〈0.0001）、平均内膜增生面积百分数（5.45%±9.26%比17.38%±13.75%,P〈0.0001）、内膜增生最大面积百分数（9.41%±14.15%比31.56%±20.99%,P〈0.0001）、平均内膜增生容积（2.09±5.46mm^3比13.43±18.59mm^3,P〈0.0001）和平均内膜增生容积百分数（1.68%±5.84%比8.62%±9.90%,P〈0.0001）较Taxus组均明显减少。结论国产西罗莫司洗脱支架（Firebird^TM）置入术后再狭窄发生率较低,与TaxusTM支架相比,抑制内膜增生作用更显著。     

Effect of abciximab-coated stent on in-stent intimal hyperplasia in human coronary arteries

The investigators tested whether abciximab-coated stents prevent neointimal hyperplasia (NIH) formation in coronary de novo lesions. Abciximab-coated stents were compared with control stents. All patients underwent follow-up coronary angiography and intravascular ultrasound (IVUS). All stents were successfully deployed, and patients were discharged home without clinical events. At follow-up coronary angiography, the restenosis rate and late loss were 14% and 0.33 +/- 0.28 mm in the abciximab-coated stent group and 28.6% and 0.64 +/- 0.32 mm in the control stent group (p = 0.099 and p = 0.014, respectively). At follow-up IVUS, the intrastent luminal area and intrastent NIH area were 5.7 +/- 1.6 and 2.0 +/- 1.6 mm(2), respectively, in the abciximab-coated stent group and 4.2 +/- 0.8 and 3.4 +/- 1.7 mm(2), respectively, in the control stent group (p = 0.001 and p = 0.001, respectively). Abciximab-coated stents are feasible and significantly inhibit NIH, with potential therapeutic benefit in preventing stent restenosis.     

Particle debris from a nanoporous stent coating obscures potential antiproliferative effects of tacrolimus-eluting stents in a porcine model of restenosis.

Polymer stent coatings may not be suitable for drug elution because of inherent proinflammatory effects. A previous study suggested a beneficial effect of a stent eluting tacrolimus from a nanoporous ceramic aluminum oxide coating in a rabbit restenosis model. We investigated whether this stent is effective in preventing in-stent restenosis in a porcine restenosis model. Thirty-four juvenile swine underwent balloon overstretch injury and were subjected to implantation of either stainless steel (bare) stents, bare stents coated with nanoporous aluminum oxide alone, and coated stents eluting 50 and 180 mug of tacrolimus (FK506). In-stent restenosis was quantified at 1 and 3 months after stent placement by histomorphometry. A significant increase of neointimal hyperplasia was noted with the stents coated with aluminum oxide alone compared with bare stents (2.92 +/- 1.02 and 1.38 +/- 0.51 mm(2), respectively; P < 0.02). In all arteries containing coated stents, particle debris was found in the media and neointima, resulting in augmented vascular inflammation. In the group of stents coated with aluminum oxide, FK506 elution at a dose 180 mug reduced neointimal hyperplasia vs. no drug elution (1.66 +/- 0.49 vs. 2.92 +/- 1.02 mm(2); 180 mug vs. ceramic alone; P < 0.03). At a dose of 50 mug stent-based delivery of FK506, no reduction of neointimal hyperplasia was found (2.88 +/- 1.31 and 2.92 +/- 1.02 mm(2), respectively; P = NS; FK506 vs. ceramic alone). In summary, particle debris shed from a drug-eluting aluminum oxide coating of a stainless steel stent counteracts potential antiproliferative effects of stent-based tacrolimus delivery in a porcine model of restenosis. We propose that stent coatings eluting drugs need to be routinely tested for being tightly anchored into the stent surface. Alternatively, omission of any coating used as a drug reservoir may eliminate inflammatory particle debris after placement of drug-eluting stents.     

Overlapping Coronary Stents Result in an Increased Neointimal Hyperplasia: Insight from a Porcine Coronary Stent Model

Clinical experience suggests that overlapping coronary stents result in an increased in-stent restenosis. This study investigates the underlying mechanisms in a porcine coronary model. Single or two overlapping self-made stainless steel single wire sinusoidal helical coil stents were randomly deployed in the right coronary artery of 20 cross-bred pigs. The pigs underwent a control angiogram at 6 weeks and were then sacrificed. Quantitative coronary analysis before, immediately after stent implantation, and at 6 weeks was performed using the semiautomated Polytron 1000 system. Morphometry was performed using a computerized morphometric program. Angiographic analysis revealed a decreased recoil in the overlapping group (1% vs 4%: P < 0.02) and a significantly larger minimal stent lumen diameter at follow-up in the single stent group (2.87 ± 0.16 vs 2.58 ± 0.22 mm, P = 0.005). Histopathology showed a significantly increased injury (1.27 ± 0.43 vs 0.83 ± 0.44, P = 0.042) and inflammatory reaction (1.51 ± 0.11 vs 1.09 ± 0.54, P = 0.035) surrounding the stent filaments in the overlapping stent group. Morphometric analysis showed a significantly higher neointimal hyperplasia (3.34 ± 0.68 vs 2.16 ± 1.48 mm², P = 0.034) in the overlapping stent group. Overlapping stents result in a more pronounced coronary vessel injury resulting in more inflammation and neointimal hyperplasia compared to single stents.     

Metallic surface modification.

The potential beneficial effect of metal surface treatment using electrochemical polishing on stent thrombogenicity and neointimal hyperplasia was evaluated in a rat A-V model and a porcine coronary model. Thrombogenicity of polished stents (n=6) was compared to non-polished stents (n=5) in a rat A-V shunt model using 125I-fibrinogen and 51Cr-labelled platelets. Total clot weight after 30 min was significantly lower in the polished stents (32.1+/-2.8 vs 18.1+/-4.4: p<0.001). Also, 125I-fibrinogen deposition was significantly lower in the polished stents (1.30+/-0.07 vs 0.66+/-0.04: p<0.001). Platelet deposition was, however, not significantly reduced (12.7+/-3.4 vs 9.87+/-1.9, NS). Subsequently, the effect of electrochemical polishing on neointimal hyperplasia was evaluated in a porcine coronary model. Polished (n=10) and non-polished stents (n=10) were randomly implanted in the right coronary artery of healthy pigs. Neointimal hyperplasia was significantly decreased in the polished stents (0.56+/-0.28 vs 0.94+/-0.34 mm2: p<0.01).     

Experimental Evaluation of a New Single Wire Tantalum Coil Coronary Stent (Wiktor-iª)

To improve scaffolding properties, a new more densely woven Wiktor stent, the Wiktor-ia stent, was developed. Although the metal coverage remains still low compared to other stents, increased metal/vessel area raises the concern of increased thrombogenicity and neointimal hyperplasia. In this study we evaluated the Wiktor-i stent in a porcine peripheral and coronary model and compared the thrombogenicity and neointimal hyperplasia with the Wiktor-GX coronary stent. In a first study, a Wiktor-i and a Wiktor-GX coronary stent were implanted symmetrically in a preselected side branch of the right and left iliac artery of 10 healthy pigs. Quantitative vessel analysis showed comparable data before, immediately after and at follow-up. Hyperplasia measured by morphometry was also comparable in both groups (Wiktor-GX: 1.43 mm2 vs. Wiktor-i: 1.17 mm2, NS). Also, area stenosis was very similar (Wiktor-GX: 32% vs. Wiktor-i: 29%, NS). In a second study, 20 Wiktor (Wiktor-i: n=10, Wiktor-GX: n=10) coronary stents were implanted in the right coronary artery of 20 healthy pigs. Quantitative coronary analysis before, immediately after and at follow-up was comparable in both stents. The hyperplasia measured morphometrically was also comparable in both stents. (Wiktor-GX: 1.51 +/- 0.47 mm2 vs. Wiktor-i: 1.46 +/- 0.66 mm2, NS). Also the area stenosis was not significantly different (Wiktor-GX: 31% vs. Wiktor-i: 35%). In conclusion, this study shows that the increased metal/vessel area of the Wiktor-i stent does not result in an increased neointimal hyperplasia. Both stents show to be very biocompatible when implanted in porcine coronary and peripheral vessels.