Schmidt Wolfram, Behrens Peter, Brandt-Wunderlich Christoph, Siewert Stefan, Grabow Niels, Schmitz Klaus-Peter
Institute for Biomedical Engineering, University Medicine Rostock, Friedrich-Barnewitz-Strasse 4, D-18119 Rostock-Warnemünde, Germany.
Institute for ImplantTechnology and Biomaterials - IIB e.V., Associated Institute of the University of Rostock, Friedrich-Barnewitz-Strasse 4, D-18119 Rostock-Warnemünde, Germany.
Cardiovasc Revasc Med. 2016 Sep;17(6):375-83. doi: 10.1016/j.carrev.2016.05.001. Epub 2016 May 13.
BACKGROUND/PURPOSE: Biodegradable polymers are the main materials for coronary scaffolds. Magnesium has been investigated as a potential alternative and was successfully tested in human clinical trials. However, it is still challenging to achieve mechanical parameters comparative to permanent bare metal (BMS) and drug-eluting stents (DES). As such, in vitro tests are required to assess mechanical parameters correlated to the safety and efficacy of the device.
METHODS/MATERIALS: In vitro bench tests evaluate scaffold profiles, length, deliverability, expansion behavior including acute elastic and time-dependent recoil, bending stiffness and radial strength. The Absorb GT1 (Abbott Vascular, Temecula, CA), DESolve (Elixir Medical Corporation, Sunnyvale, CA) and the Magmaris (BIOTRONIK AG, Bülach, Switzerland) that was previously tested in the BIOSOLVE II study, were tested.
Crimped profiles were 1.38±0.01mm (Absorb GT1), 1.39±0.01mm (DESolve) and 1.44±0.00mm (Magmaris) enabling 6F compatibility. Trackability was measured depending on stiffness and force transmission (pushability). Acute elastic recoil was measured at free expansion and within a mock vessel, respectively, yielding results of 5.86±0.76 and 5.22±0.38% (Absorb), 7.85±3.45 and 9.42±0.21% (DESolve) and 5.57±0.72 and 4.94±0.31% (Magmaris). Time-dependent recoil (after 1h) was observed for the Absorb and DESolve scaffolds but not for the Magmaris. The self-correcting wall apposition behavior of the DESolve did not prevent time-dependent recoil under vessel loading.
The results of the suggested test methods allow assessment of technical feasibility based on objective mechanical data and highlight the main differences between polymeric and metallic bioresorbable scaffolds.
背景/目的：可生物降解聚合物是冠状动脉支架的主要材料。镁已被研究作为一种潜在的替代品，并在人体临床试验中成功进行了测试。然而，要实现与永久性裸金属支架（BMS）和药物洗脱支架（DES）相当的机械参数仍具有挑战性。因此，需要进行体外测试以评估与器械安全性和有效性相关的机械参数。
方法/材料：体外台架试验评估支架的外形、长度、输送性、扩张行为，包括急性弹性回缩和时间依赖性回缩、弯曲刚度和径向强度。对Absorb GT1（雅培血管，加利福尼亚州特梅库拉）、DESolve（Elixir医疗公司，加利福尼亚州森尼韦尔）以及先前在BIOSOLVE II研究中测试过的Magmaris（百多力公司，瑞士比拉赫）进行了测试。
卷曲外形分别为1.38±0.01毫米（Absorb GT1）、1.39±0.01毫米（DESolve）和1.44±0.00毫米（Magmaris），可兼容6F导管。根据刚度和力传递（推送性）测量可跟踪性。分别在自由扩张和模拟血管内测量急性弹性回缩，结果为5.86±0.76%和5.22±0.38%（Absorb）、7.85±3.45%和9.42±0.21%（DESolve）以及5.57±0.72%和4.94±0.31%（Magmaris）。观察到Absorb和DESolve支架存在时间依赖性回缩（1小时后），而Magmaris支架未出现。DESolve的自校正贴壁行为在血管加载下并不能防止时间依赖性回缩。
所建议测试方法的结果能够基于客观的机械数据评估技术可行性，并突出了聚合物和金属生物可吸收支架之间的主要差异。
