Tohfafarosh Mariya, Sevit Alex, Patel Jasmine, Kiel Jonathan W, Greenspon Arnold, Prutkin Jordan M, Kurtz Steven M
School of Biomedical Engineering, Science and Health Systems, Drexel University, Philadelphia, PA.
Exponent, Inc., Philadelphia, PA.
J Long Term Eff Med Implants. 2016;26(3):225-232. doi: 10.1615/JLongTermEffMedImplants.2016016455.
Success of pacemakers and implantable cardioverter defibrillators may be limited by premature lead failure. Lead insulation polymers, such as polyurethane (PU) and polydimethylsiloxane (PDMS), are reported to degrade over time in vivo. PU is known to undergo oxidation, whereas PDMS undergoes surface hydrolysis. Previous studies have characterized polymer degradation in vitro, in animals or in short-term human study; however, complex effects of the biochemical and mechanical environment on the lead insulation can only be fully understood by evaluating long-term-implanted leads. Therefore, we established a retrieval program to systematically characterize the chemical and surface changes in 37 of 104 retrieved pacing and defibrillator leads, implanted for ≥5 yr. Fourier transform infrared (FTIR) spectroscopy was used for chemical analysis, and a scanning electron microscope was used for surface degradation evaluation. PDMS leads were investigated for changes in the ratio of Si-O-Si to Si-C peaks, whereas PU degradation was evaluated by changes in ether (C-O-C), carbonyl (C=O), methylene (C-H), and amino (C-N/N-H) peaks. Under SEM, PDMS showed enhanced roughness but no statistical increase in Si-O-Si bonds. PU showed uniform cracking throughout the lead body and statistical changes in each of the oxidation indicative peaks. Overall, both polymers showed surface changes in the physiological environment, but PU was the only material to show chemical changes. This work is a large-scale characterization study on long-term-implanted leads that confirmed PU oxidation but not hydrolysis of PDMS in vivo. It provides important insight for manufacturers when making design improvements and for surgeons when making decisions about lead implantation.
起搏器和植入式心脏复律除颤器的成功应用可能会受到导线过早失效的限制。据报道，诸如聚氨酯（PU）和聚二甲基硅氧烷（PDMS）等导线绝缘聚合物会在体内随时间降解。已知PU会发生氧化，而PDMS会发生表面水解。先前的研究已在体外、动物或短期人体研究中对聚合物降解进行了表征；然而，只有通过评估长期植入的导线，才能全面了解生化和机械环境对导线绝缘的复杂影响。因此，我们建立了一个回收计划，以系统地表征104根回收的起搏和除颤导线中的37根（植入时间≥5年）的化学和表面变化。采用傅里叶变换红外（FTIR）光谱进行化学分析，并用扫描电子显微镜进行表面降解评估。对PDMS导线研究了Si-O-Si与Si-C峰的比例变化，而通过醚（C-O-C）、羰基（C=O）、亚甲基（C-H）和氨基（C-N/N-H）峰的变化评估PU降解。在扫描电子显微镜下，PDMS显示粗糙度增加，但Si-O-Si键无统计学意义的增加。PU在整个导线体上显示出均匀的开裂，且每个氧化指示峰都有统计学变化。总体而言，两种聚合物在生理环境中均显示出表面变化，但PU是唯一显示化学变化的材料。这项工作是一项关于长期植入导线的大规模表征研究，证实了体内PU的氧化，但未证实PDMS的水解。它为制造商进行设计改进以及外科医生在决定导线植入时提供了重要的见解。
