Institute for ImplantTechnology and Biomaterials e.V., Rostock-Warnemuende, Germany.
BIOTRONIK AG, Buelach, Switzerland.
J Mech Behav Biomed Mater. 2019 Mar;91:174-181. doi: 10.1016/j.jmbbm.2018.12.008. Epub 2018 Dec 11.
Resorbable magnesium scaffolds are used for the treatment of atherosclerotic coronary vascular disease and furthermore, for vascular restoration therapy. Recently, the first-in-man clinical studies with Magmaris showed promising results regarding the target lesion failure as well as vasomotion properties after 12 and 24 month. The consistency of in vivo degraded magnesium alloys in a cardiovascular environment is qualitatively described in literature, but only little has been disclosed about the actual change in mechanical properties and the behavior of the magnesium alloy degradation products. In the present study, uncoated magnesium scaffolds 3.0 × 20 mm were implanted in coronary arteries of two healthy Goetinnger mini-swine. The scaffolds were explanted to evaluate the mechanical properties of the degraded magnesium scaffolds after 180 days in vivo. Ex vivo sample preparation and test conditions were adapted to a customized compression test setup which was developed to investigate the micro-scale scaffold fragments (width 225 ± 75 µm, thickness 150 µm). As reference bare undegraded magnesium scaffold fragments were tested. Mechanical parameters relating to force as a function of displacement were determined for both sample groups. The undegraded samples showed no fracturing at the maximum applied force of 8 N, whereas the in vivo degraded test samples showed forces of 0.411 ± 0.197 N at the first fracturing and a maximum force of 0.956 ± 0.525 N. The deformation work, calculated as area beneath the force-displacement curve, of the in vivo degraded test samples was reduced by approximately 87-88% compared to the undegraded samples (5.20 mN mm and 40.79 mN mm, both at 7.5% deformation). The indication for a complete loss of structural integrity through a reduction of mechanical properties after a certain degradation time increases the chance to restore vascular function and physiological vasomotion in the stented vessel compartment.
可吸收镁支架用于治疗动脉粥样硬化性冠状动脉疾病，并且还用于血管修复治疗。最近，Magmaris 的首例人体临床研究显示出有希望的结果，即 12 个月和 24 个月后的靶病变失败和血管运动特性。文献中定性描述了心血管环境中体内降解镁合金的一致性，但仅很少揭示镁合金降解产物的实际机械性能变化和行为。在本研究中，将未涂层的 3.0×20mm 镁支架植入两只健康的 Goetinnger 小型猪的冠状动脉中。将支架取出以评估在体内 180 天后降解的镁支架的机械性能。体外样本制备和测试条件适应于定制的压缩测试装置，该装置旨在研究微尺度支架碎片（宽度 225±75µm，厚度 150µm）。将未降解的镁支架碎片作为参考进行了测试。确定了与力作为位移函数相关的机械参数。未降解的样品在最大应用力 8N 时没有断裂，而体内降解的测试样品在第一次断裂时显示出 0.411±0.197N 的力，最大力为 0.956±0.525N。与未降解的样品相比，体内降解的测试样品的变形功（计算为力-位移曲线下的面积）降低了约 87-88%（分别为 5.20mNmm 和 40.79mNmm，均在 7.5%变形时）。在一定的降解时间后，由于机械性能降低而导致结构完整性完全丧失的迹象增加了恢复支架血管腔中血管功能和生理血管运动的机会。
