【作者】 宗刚军；

【导师】 秦永文； 赵仙先；

【作者基本信息】 第二军医大学 ， 内科学， 2008， 博士

【摘要】 研究背景:在过去的几年里,经皮瓣膜置换技术得到飞速的发展。目前,一些经皮置换主动脉瓣、肺动脉瓣的方法在国外已经用于临床。2000年9月,Bonhoeffer等首次成功的为一例12岁右心室流出道-肺动脉瓣严重狭窄的患者,经皮通过股静脉入路,在肺动脉瓣位置植入带瓣膜支架进行肺动脉瓣膜置换,开创了人经皮肺动脉瓣膜置换的先河。到目前为止,该技术成为了目前经导管瓣膜置换术中最成功,临床应用经验最多的瓣膜病介入治疗新方法。经皮肺动脉瓣膜置换技术由梦想变成了现实。尽管这项技术目前还面临着这样那样的问题,包括:瓣膜在支架内缝合的合适位置;瓣膜经导管被压缩、释放过程中如何保护瓣膜的功能;瓣膜支架的固定以及如何避免瓣膜周围漏等问题。但是,8年来的临床证据证实,这种非外科的治疗方法不仅可行,而且充满希望。新的带瓣膜支架装置以及不同植入路经的研究一直倍受国内外研究人员的关注。为了克服目前存在的问题,推动带瓣膜肺动脉支架装置的国产化,降低费用,以使该技术在我国的开展和推广,我们与上海形状记忆合金有限公司合作,设计一种新型的自膨胀带瓣膜肺动脉支架装置,进行了经导管植入置换肺动脉瓣的实验研究。研究目的:评价使用新型自膨胀带瓣膜支架装置,经导管植入到实验山羊的肺动脉瓣位置的可行性、安全性和瓣膜支架功能,为临床应用提供依据。研究方法:(1)经导管肺动脉瓣置换的应用解剖研究:分别解剖测量40例经防腐固定的外形大小正常的成人心脏标本,以及20只新鲜的健康山羊心脏标本。先观察肺动脉瓣膜区解剖位置及毗邻关系,然后分别测量肺动脉瓣环的周径;肺动脉瓣游离缘、附着缘长度;窦底到瓣叶游离缘的最大距离;主肺动脉开口到肺动脉分叉的距离。同时,通过彩超、肺动脉瓣上造影测量8只实验山羊的肺动脉瓣膜环直径。(2)带瓣膜肺动脉支架及输送系统研制:我们与上海形状记忆合金有限公司合作,以国产镍钛合金丝为材料,编织自膨胀支架,支架由头部、颈部和体部三个部分组成。人工瓣膜以新鲜的猪心包为材料,先给予0.01%胰蛋白酶中震荡脱细胞处理后24小时,后给予0.6%戊二醛液4℃浸泡36小时,再用2%L-谷氨酸浸泡24小时去除戊二醛毒性。将处理好的心包裁剪成瓣叶,缝合在瓣膜环上,构成人工瓣膜,最后将人工瓣膜固定在支架上,组成带瓣膜肺动脉支架。带瓣膜支架保存在60%的酒精溶液中,使用前换75%酒精浸泡24小时灭菌,在植入前用生理盐水反复冲洗去除酒精。输送系统是由扩张管、外鞘管、连接短鞘以及推送杆组成,使用前肝素水冲洗。(3)经导管肺动脉瓣膜置换实验研究:健康清洁级实验山羊16只,随机分为2组,每组8只,一组为经皮经导管植入带瓣膜支架组(A组),另一组开胸经导管植入带瓣膜支架组(B组)。A组切开股静脉,建立输送轨道,经输送鞘管,将带瓣膜支架植入到肺动脉瓣膜区。B组通过开胸,穿刺右室前壁,经到导管植入带瓣膜肺动脉支架。两组实验山羊术后进行了6个月的影像学、血流动力学随访,同时,在术后12小时和6个月分别进行解剖学和组织学的评估。(4)带瓣膜支架植入治疗肺动脉瓣返流实验研究:健康清洁级实验山羊6只,体重(26.6±3.2)kg,先给予经皮经导管在肺动脉瓣膜区植入直径为0.18 mm镍钛合金丝编织管状支架,支架将原肺动脉瓣膜压在支架与主肺动脉间,建立肺动脉瓣关闭不全模型,观察2周后,经皮植入带瓣膜肺动脉支架,术后给予影像学、血流动力学的随访。(5)经导管带瓣膜肺动脉支架二次植入实验研究:健康清洁级实验山羊6只,体重(26.1±3.7)kg,先给予经皮经导管植入带瓣膜支架置换肺动脉瓣,饲养2个月后,给予二次经皮经导管植入带瓣膜支架置换第一次植入的人工肺动脉瓣膜。术后给予影像学、血流动力学的随访。结果:(1)正常成人和实验山羊测得肺动脉瓣周径分别为(66.5±11.3)mm、(56.4±7.4)mm;瓣膜游离缘长度分别为(27.5+5.2)mm、(20.1±2.4)mm;瓣膜附着缘长度分别为(21.3±4.6)mm、(16.4±2.3)mm;游离缘距窦底的距离分别为(16.5±4.3)mm、(10.9±2.2)mm;主肺动脉长度分别为(33.5±8.2)mm、(28.3±3.2)mm;彩超测实验山羊肺动脉瓣膜环直径(14.9±1.1)mm,造影测肺动脉瓣膜环直径(15.6±1.0)mm。(2)带瓣膜支架设计成类似酒杯状结构,与右室流出道-肺动脉区解剖结构相匹配,可以锚定在肺动脉瓣膜区,不易移位,其颈部直径在18-24mm,可以收入14F的鞘管中,通过血管途径植入。输送鞘管有良好的柔韧性,容易到位,推送装置可靠,推送过程对人工瓣膜无影响。(3)A组8只实验羊中,7只实验羊手术成功;B组8只实验羊中,7只实验羊即时成功,1只羊术后4个月死于肺动脉支架内血栓形成。两组实验山羊术后6个月心脏彩超提示人工肺动脉瓣膜启闭正常,无明显狭窄及关闭不全,心功能与术前比较无明显变化;右心室以及人工肺动脉瓣上造影证实支架的位置及瓣膜功能良好;64排螺旋CT增强扫描发现支架无移位。术后即刻解剖见支架位置良好,肺动脉瓣被压在支架与肺动脉瓣膜环之间,带瓣膜支架锚定牢靠。术后6个月,解剖见支架无移位,透明的内膜组织覆盖支架表面,扫描电镜下见支架上覆盖内皮细胞形态成熟,较饱满,排列致密有序,细胞长轴与血流方向一致。(4)6只实验羊中5只成功的建立肺动脉瓣返流模型,肺动脉瓣被压在支架与肺动脉瓣膜环之间,彩超以及血管造影证实模型成功。1只羊术后1周死于急性肺动脉瓣膜返流,4只肺动脉瓣返流模型羊成功的进行了经皮带瓣膜肺动脉瓣膜支架的植入,术后即刻以及2个月心脏彩超以及血管造影证实植入的人工瓣膜功能良好。(5)6只实验羊成功的进行经皮带瓣膜肺动脉支架的植入。植入2月后,5只羊成功的给予带瓣膜肺动脉支架二次植入,植入过程操作安全,无任何手术相关的并发症。术后即刻以及2个月心脏彩超以及血管造影证实植入的第二次植入的人工瓣膜功能良好。结论:自行研制的新型带瓣膜肺动脉支架装置及相匹配的输送系统,成功的应用于实验山羊的经导管植入,随访效果理想。新型带瓣膜肺动脉支架设计简约、合理,质量稳定,植入过程方便,安全可行,生物相容性好,是可以提供临床试验用的带瓣膜支架。更多还原

【Abstract】 Background:Developmemal efforts to achieve percutaneous catheterbased therapies for cardiac valve replacemem have advanced rapidly over the past several years.A variety of methods to replace aortic and pulmonic valves have already been successfully employed in patients.The first successful human percutaneous implantation of a catheter-based stent valve was accomplished in the pulmonary valve position by Bonhoeffer in 2000.The stent valve was delivered percutaneously via the femoral vein in a 12-year-old boy with a severely stenosed pulmonary valve in a right ventricle-to-pulmonary artery conduit.To date,it also represents the most successful and clinically applicable experience of transcatheter valve technology.Percutaneous pulmonary valve implantation,once considered only a novel idea,has become a reality.This nonsurgical approach has been proven to be feasible and hold promise,although many obstacles still exist.These difficulties include optimal attachment of the valve into the stent,preservation of the function of the valved stent after compression and re-expansion,functional anchoring mechanism,and avoidance of paravalvular regurgitation.To overcome these problems,new stent designs and operative and intervemional hybrid approaches are under investigation.We cooperated with the Shanghai Shape-Memory Alloys Material Limited Company to develop a new-type self-expanding valved stent and device for making it become homemade manufacture and decreasing its price in our country as quickly as possible.We performed serial experiments to investigate the feasibility of transcatheter implamation of this valved stent in pulmonary valve.Objectives:To evaluate the the feasibility,safety and function of transcatheter implanted new-type self-expanding valved stem imo the pulmonary position of sheep.Methods:(1) Applied anatomy of transcatheter pulmonary valve replacement:Forty adult heart specimens and twenty fresh healthy sheep hearts were dissected and measured. Observe the anatomic position of pulmonary valve,and the relationship between the pulmonary valve and adjacem structure firstly.The perimeter of pulmonary valve annulus, the length of free margin and attachmem margin were measured respectively.The distance from free margin to sinus bottom and the long diameter of primary pulmonary artery were measured also.The diameter of pulmonary valve annulus was measured by ultrasound and angiography,respectively.(2) Development of the valved stent and delivery system:We cooperated with the ShangHai Shape-Memory Alloys Material Limited Company to develop a new-type valved stent and delivery system.We applied the homemade nitinol alloy to braid self-expanding stent which consists of three parts.The head,cervical part and caudomedial part are called.A fresh pig pericardium was shaked in a 0.01%trypsin solution for 24 hours then cross-linked with a 0.6%glutaraldehyde solution for 36 hours at 4℃.The pericardium was removed toxicity of glutaraldehyde in 2%L-glutamic acid solution for 24 hours then sutured into a valvular ring that was sutured onto a newly designed nitinol self-expandable stent.After fixation,it was transferred to a 60%ethanol solution for storage.The valve assembly was immersed in a 75%ethanol solution 24 hours for sterilization and carefully soaked in a physiological saline solution to remove the ethanol before implantation.The delivery system consisted of an external sheath,dilated sheath,short connection sheath,a matched cable and was flushed using a heparinized saline solution.(3) Experimental study of transeatheter pulmonary valve replacement: Sixteen sheeps were included.Animals were divided into two groups.In the one(n=8) group(group A),we intended to implant valved stent percutaneously via the femoral vein. In the other(n=8) group(group B),we expected to implant valved stent via the anterior wall of fight ventricle by catheter.Hemodynamic evalution and imaging examination was carried out during the periodical follow up after implantation.Additionally,anatomic and histological evalution were performed at six months after implantation.(4) Transeatheter implantation of nitinol valved stent for treatment of pulmonary regurgitation in sheep model:Six sheeps weighing(26.6±3.2) kg were included.A self-expandable cylindrical stent was constructed from a 0.18mm nitinol wire.The cylindrical stent was implanted in the pulmonary valve position percutaneously.After two weeks,a self-expandable valved stent was implanted in the right ventricle-to-pulmonary artery position percutaneously via the femoral vein.Hemodynamic evalution and imaging examination was carried out during the periodical follow up after implantation.(5) Experimental study of second transeatheter pulmonary valved stent implantion:Six sheeps weighing(26.1±3.7) kg were included.A self-expandable valved stent was implanted in the pulmonary valve position percutaneously via the femoral vein.After 2 months,the otherself-expandable valved stent was implanted in first valved stent position percutaneously.Hemodynamic evalution and imaging examination was carried out during the periodical follow up after implantation.Results:(1) The perimeter of pulmonary valve annulus of adult and sheep were (66.5±11.3) mm and(56.4±7.4) mm respectively.The length of free margin were (27.5±5.2) mm and(20.1±2.4) mm respectively.The length of attachment margin were (21.3±4.6) mm and(16.4±2.3) mm respectively.The distance from free margin to sinus bottom were(16.5±4.3) mm and(10.9±2.2) mm respectively.The long diameter of primary pulmonary artery were(33.5±8.2) mm and(28.3±3.2) mm respectively.The mean diameter of the pulmonary annulus was(14.9±1.1 ) mm and(15.6±1.0) mm as revealed by ultrasound and angiography,respectively.(2) We developed a new-type valved stent like wine cup which matches to right ventricle-to-pulmonary artery conduit morphologies so as to be anchored safely to prevent device dislodgement.The outer diameter of the stent cervical part ranges 18～24 mm.The valved stent inserted into 14F external sheath.The delivery system has high flexibility which assure a geometric adaptation from peripheral vein to pulmonary.(3) In group A,7 of 8 devices were successfully delivered.In group B, the pulmonary valved stent had been implanted in seven sheeps successfully.One sheep died 4 months after the procedure due to thrombosis on stent leading to subtotal stenosis. Echocardiographic imaging also showed that the valved stents were in the desired position after 6 months.No moderate to severe pulmonary regurgitation or stenosis was observed. Angiographic and hemodynamic studies confirmed good position and function of the stents with a competent valve in early and 6 months after the procedure.The 64-slice CT image showed that the stent were good position.At 12 hours after implantation,macroscopic findings at autopsy showed that the pulmonary native valves were stuck between the annulus and stent.The pulmonary valved stent was fully deployed and anchored to the annulus.The stent of the 6 months sheep had been covered by a layer of transparent membranous tissue.Endothelial cell covered the devices smoothly under SEM.The endothelial cell and fibrosis had been mature.(4) Pulmonary regurgitation were successfully created through the implantation of stents in 5 of 6 sheeps with regurgitation documented on pulmonary arteriography and TTE after the procedure.The pulmonary native valves were stuck between the annulus and stent.Acute onset of pulmonary regurgitation was poorly tolerated in one animal.The pulmonary valved stent had been implanted in four pulmonary regurgitation model sheeps successfully.Echocardiographic and angiographic studies confirmed good position and function of the stents with a competent valve in 2 months after the procedure.(5) Six pulmonary valved stents were successfully delivered percutaneously.After 2 months,the other self-expandable valved stent was implanted percutaneously in five sheeps successfully.No complications were noted during the procedure or the follow-up.Echocardiographic and angiographic studies confirmed good position and function of the second valved stents in 2 months after the procedure.Conclusions:The self-manufactured pulmonary valved stent was implanted into the pulmonary position of sheep successfully,which has good structural stability and excellent biocompatibility.The study shows that the new-type valved stent and delivery system were safe,feasible and efficient.The results support the investigation of the valved stent in human clinical trials.更多还原