Department of Diagnostic and Interventional Radiology and Nuclear Medicine, Charité Campus Virchow-Klinikum, Charité University Medicine Berlin, Germany.
Department of Vascular Surgery, St Franziskus Hospital Münster, Germany.
J Endovasc Ther. 2019 Dec;26(6):787-794. doi: 10.1177/1526602819866435. Epub 2019 Aug 5.
To investigate 2 generations of balloon-expandable covered stents as potential bridging devices using an in vitro model of stent-graft fenestrations. Twenty BeGraft and 20 BeGraft+ cobalt-chromium stents covered in expanded polytetrafluoroethylene (ePTFE) in 6- and 8-mm diameters were tested in sheets mimicking stent-graft fenestrations. Microscopy and radiography were employed to evaluate stent morphology after flaring. In vitro bench tests measured maximum pullout (perpendicular displacement) and the shear stress (axial displacement) forces needed to dislocate the stents. No alteration of ePTFE coverage was detected in the flared stents. Digital radiography and computed tomography showed marked alteration of the stent geometry, which was more pronounced in the BeGraft group. No fractures were detected. Median (minimum-maximum) pullout forces for the 6-mm stent-grafts were 17.1 N (15.8-19.6) for the BeGraft device and 30.4 N (20.2-31.9) for the BeGraft+ device (p=0.006). Median (minimum-maximum) pullout forces for the 8-mm stent-grafts were 11.3 N (11-12.1) for the BeGraft device and 21.8 N (18.2-25.5) for the BeGraft+ device (p<0.001). The shear stress test showed median forces of 10.5 vs 15.28 N at 150% of the stent diameter for the 6-mm BeGraft and BeGraft+ stent-grafts, respectively, and 15.23 vs 20.72 N at 150% stent diameter for the 8-mm models (p=0.016 and 0.017, respectively). Flaring changed the stent geometry but did not provoke stent fractures. The BeGraft+ is superior to the BeGraft in terms of pullout and shear stress forces, demonstrating greater resilience.
为了研究两代球囊扩张覆膜支架作为潜在的桥接装置，我们使用支架-移植物开窗的体外模型进行了研究。 6 毫米和 8 毫米直径的 20 个 BeGraft 和 20 个 BeGraft+ 钴铬覆膜支架用膨体聚四氟乙烯（ePTFE）覆盖，在模拟支架-移植物开窗的片材上进行测试。显微镜和放射照相术用于评估扩口后的支架形态。体外台架试验测量了使支架脱位所需的最大拔出力（垂直位移）和剪切力（轴向位移）。 扩口后的支架中未检测到 ePTFE 覆盖物的变化。数字放射摄影术和计算机断层扫描显示支架几何形状的明显改变，BeGraft 组更为明显。未检测到骨折。6 毫米支架-移植物的中位（最小-最大）拔出力为 BeGraft 装置 17.1 N（15.8-19.6）和 BeGraft+装置 30.4 N（20.2-31.9）（p=0.006）。8 毫米支架-移植物的中位（最小-最大）拔出力为 BeGraft 装置 11.3 N（11-12.1）和 BeGraft+装置 21.8 N（18.2-25.5）（p<0.001）。在 6 毫米 BeGraft 和 BeGraft+支架-移植物的 150%支架直径处，剪切力试验分别显示出 10.5 与 15.28 N 的中位力，在 8 毫米模型中分别为 15.23 与 20.72 N 的中位力（p=0.016 和 0.017）。扩口改变了支架的几何形状，但没有引起支架断裂。BeGraft+在拔出力和剪切力方面优于 BeGraft，表现出更强的弹性。
