Kalmár Gábor, Hübner Friederike, Voelker Wolfram, Hutzenlaub Jens, Teubner Joachim, Poerner Tudor, Süselbeck Tim, Borggrefe Martin, Haase Karl K
Department of Medicine I, Universitätsklinikum Mannheim, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany.
J Vasc Interv Radiol. 2002 May;13(5):499-508. doi: 10.1016/s1051-0443(07)61530-9.
Important criteria for optimized stent implantation are high radial force and complete apposition of the stent itself. The aim of this study was to develop a simple method to assess these parameters under controlled experimental conditions and to compare vascular stents of different designs with regard to these parameters.
Five balloon-expandable stents of different designs (Jostent Flex, MAC stent, ML-Tristar, ML-Ultra, and S670) were tested. Fourteen stents of each type were implanted in a curved plastic vessel model (curve radius, 10 mm; lumen diameter, 3.5 mm) with use of a balloon inflation pressure of 12 atm. Part of the model was a nonflexible eccentric stenosis which was 2 mm or 8 mm in length. After stent implantation, a stenosis of 10%-70% was induced and radial force of the stent struts was measured at the site of the stenosis. The apposition of the stent to the vessel wall was imaged by high-resolution radiography.
Analysis of variance showed significant differences of radial force between the tested stents (P <.001). The ML-Tristar and ML-Ultra stents had the highest radial force with maximum mean values of 687 cN and 846 cN at a stenosis of 70% in the model with the long stenosis. The radial force of the S670 stent was the lowest whereas the MAC stents showed an intermediate radial force. Radial force of the ML-Ultra stent was as much as 3.8 times higher than the force of the S670 stent (P <.001). Fifty percent of the ML-Tristar and ML-Ultra stents did not expand sufficiently to touch the vessel surface at the outer curvature. With an inflation pressure of 17 atm, complete apposition of these stents was achieved. The highest number of apposition irregularities was found in the S670 group (13 of 14 stents), whereas the MAC stents revealed the lowest number of irregular appositions (three of 14 stents). A significant correlation was found between the number of interconnecting struts and the number of irregular apposition events (P <.01).
This model allows an accurate in vitro evaluation of different stent parameters, such as apposition to the vessel wall and radial force. None of the investigated stents showed optimal results with respect to both parameters. The apposition behavior was significantly influenced by the architecture of the stents.
优化支架植入的重要标准是高径向力和支架自身的完全贴壁。本研究的目的是开发一种在可控实验条件下评估这些参数的简单方法，并比较不同设计的血管支架在这些参数方面的差异。
测试了五种不同设计的球囊扩张支架（Jostent Flex、MAC支架、ML-Tristar、ML-Ultra和S670）。每种类型的14个支架通过使用12个大气压的球囊膨胀压力植入弯曲的塑料血管模型（弯曲半径10毫米；管腔直径3.5毫米）中。模型的一部分是长度为2毫米或8毫米的非柔性偏心狭窄。支架植入后，诱导出10%-70%的狭窄，并在狭窄部位测量支架支柱的径向力。通过高分辨率射线照相术对支架与血管壁的贴壁情况进行成像。
方差分析显示，测试的支架之间径向力存在显著差异（P<.001）。在长狭窄模型中，当狭窄率为70%时，ML-Tristar和ML-Ultra支架的径向力最高，最大平均值分别为687厘牛和846厘牛。S670支架的径向力最低，而MAC支架的径向力处于中等水平。ML-Ultra支架的径向力比S670支架的力高3.8倍（P<.001）。50%的ML-Tristar和ML-Ultra支架在外侧弯曲处未充分扩张至接触血管表面。在17个大气压的膨胀压力下，这些支架实现了完全贴壁。S670组中发现的贴壁不规则情况数量最多（14个支架中有13个），而MAC支架中发现的不规则贴壁数量最少（14个支架中有3个）。发现连接支柱的数量与不规则贴壁事件的数量之间存在显著相关性（P<.01）。
该模型能够对不同的支架参数进行准确的体外评估，如与血管壁的贴壁情况和径向力。在所研究的支架中，没有一个在这两个参数方面都显示出最佳结果。贴壁行为受到支架结构的显著影响。
