Rozeik Monica M, Wheatley David J, Gourlay Terence
Department of Biomedical Engineering, Wolfson Centre, University of Strathclyde, 106 Rottenrow, Glasgow, G4 0NW, UK.
Cardiovasc Eng Technol. 2017 Sep;8(3):357-367. doi: 10.1007/s13239-017-0313-2. Epub 2017 Jun 16.
The current delivery size of transcatheter aortic valves, limited by the thickness of their pericardial leaflets, correlates with a high prevalence of major vascular complications. Polyurethane valves can be developed to a fraction of the thickness of pericardial valves through the addition of carbon nanotubes to reinforce their leaflets. This study investigates the suitability of a novel carbon nanotube reinforced leaflet to reduce the delivery profile of transcatheter aortic valves. Carbon nanotube polyurethane composites were developed with thicknesses of 50 μm and their mechanical properties were determined in relation to various environmental effects. The composites demonstrated improvements to the material stiffness, particularly at increasing strain rates compared to the neat polymer. However, increasing nanotube concentrations significantly decreased the fatigue life of the composites. Key findings highlighted a potential for carbon nanotube reinforcement in valve replacement which experience very high strain rates during the cardiac cycle. Further testing is needed to achieve a strong nanotube-matrix interface which will prolong the cyclic fatigue life and further strengthen tensile properties. Testing on the durability and haemocompatibility of these composite heart valves are ongoing.
目前经导管主动脉瓣的输送尺寸受心包瓣叶厚度限制，与主要血管并发症的高发生率相关。通过添加碳纳米管增强瓣叶，聚氨酯瓣膜的厚度可减小至心包瓣膜的几分之一。本研究调查了新型碳纳米管增强瓣叶对降低经导管主动脉瓣输送轮廓的适用性。开发了厚度为50μm的碳纳米管聚氨酯复合材料，并测定了其与各种环境影响相关的力学性能。与纯聚合物相比，复合材料的材料刚度有所提高，尤其是在应变率增加时。然而，增加纳米管浓度会显著降低复合材料的疲劳寿命。主要研究结果突出了碳纳米管增强在瓣膜置换中的潜力，因为在心动周期中瓣膜会经历非常高的应变率。需要进一步测试以实现强大的纳米管 - 基体界面，从而延长循环疲劳寿命并进一步增强拉伸性能。目前正在对这些复合心脏瓣膜的耐久性和血液相容性进行测试。
