Rotman Oren M, Kovarovic Brandon, Bianchi Matteo, Slepian Marvin J, Bluestein Danny
From Department of Biomedical Engineering, Stony Brook University, Stony Brook, New York.
Department of Biomedical Engineering, University of Arizona, Tucson, Arizona.
ASAIO J. 2020 Feb;66(2):190-198. doi: 10.1097/MAT.0000000000000980.
Transcatheter aortic valve replacement (TAVR) has emerged as an effective therapy for the unmet clinical need of inoperable patients with severe aortic stenosis (AS). Current clinically used tissue TAVR valves suffer from limited durability that hampers TAVR's rapid expansion to younger, lower risk patients. Polymeric TAVR valves optimized for hemodynamic performance, hemocompatibility, extended durability, and resistance to calcific degeneration offer a viable solution to this challenge. We present extensive in vitro durability and stability testing of a novel polymeric TAVR valve (PolyNova valve) using 1) accelerated wear testing (AWT, ISO 5840); 2) calcification susceptibility (in the AWT)-compared with clinically used tissue valves; and 3) extended crimping stability (valves crimped to 16 Fr for 8 days). Hydrodynamic testing was performed every 50M cycles. The valves were also evaluated visually for structural integrity and by scanning electron microscopy for evaluation of surface damage in the micro-scale. Calcium and phosphorus deposition was evaluated using micro-computed tomography (μCT) and inductive coupled plasma spectroscopy. The valves passed 400M cycles in the AWT without failure. The effective orifice area kept stable at 1.8 cm with a desired gradual decrease in transvalvular pressure gradient and regurgitation (10.4 mm Hg and 6.9%, respectively). Calcium and phosphorus deposition was significantly lower in the polymeric valve: down by a factor of 85 and 16, respectively-as compared to a tissue valve. Following the extended crimping testing, no tears nor surface damage were evident. The results of this study demonstrate the potential of a polymeric TAVR valve to be a viable alternative to tissue-based TAVR valves.
经导管主动脉瓣置换术（TAVR）已成为一种有效的治疗方法，可满足重度主动脉瓣狭窄（AS）无法手术患者未得到满足的临床需求。目前临床上使用的组织TAVR瓣膜耐久性有限，这阻碍了TAVR向更年轻、风险更低的患者群体迅速扩展。针对血流动力学性能、血液相容性、延长耐久性和抗钙化变性进行优化的聚合物TAVR瓣膜为这一挑战提供了可行的解决方案。我们对一种新型聚合物TAVR瓣膜（PolyNova瓣膜）进行了广泛的体外耐久性和稳定性测试，测试内容包括：1）加速磨损测试（AWT，ISO 5840）；2）钙化敏感性（在AWT中）——与临床使用的组织瓣膜进行比较；3）延长的压接稳定性（瓣膜压接到16 Fr，持续8天）。每50M次循环进行一次流体动力学测试。还通过目视评估瓣膜的结构完整性，并通过扫描电子显微镜评估微观尺度上的表面损伤。使用微型计算机断层扫描（μCT）和电感耦合等离子体光谱法评估钙和磷的沉积情况。瓣膜在AWT中通过了400M次循环而未出现故障。有效瓣口面积稳定在1.8平方厘米，跨瓣压差和反流（分别为10.4毫米汞柱和6.9%）呈预期的逐渐下降。与组织瓣膜相比，聚合物瓣膜中的钙和磷沉积显著降低，分别降低了85倍和16倍。经过延长的压接测试后，未发现撕裂或表面损伤。本研究结果表明，聚合物TAVR瓣膜有可能成为组织型TAVR瓣膜的可行替代品。
