Gabbay S, Bortolotti U, Wasserman F, Factor S M
Eur Heart J. 1984 Oct;5 Suppl D:65-71. doi: 10.1093/eurheartj/5.suppl_d.65.
The haemodynamic characteristics and durability of mitral bioprostheses were evaluated and compared in vitro in a pulse duplicator and in a fatigue test system. Porcine xenografts were shown to be the most stenotic of all bioprostheses, studied at rates simulating both rest and exercise; on the other hand the new generation of biological valves showed a clear improvement in haemodynamics compared with the standard porcine and pericardial prostheses so far used clinically. Durability tests performed at a rate of 1600 to 1800 beats per minute and with a closing pressure ranging from 80 to 100 mmHg showed that the Ionescu-Shiley and Edwards pericardial xenografts last significantly longer than the Hancock and Carpentier Edwards porcine valves and Hancock pericardial bioprosthesis. Correlation between the mode of failure of pericardial and porcine valves in vitro and in vivo clearly demonstrates that a major role in valve failure is played by mechanical stress. This can be either a consequence of the continuous trauma sustained by the tissue hitting against the bare dacron cloth of the sewing ring during the movements of the cusps. or a result of fatigue occurring and the bending points of the leaflets. The results of this study underline the importance of a continued in vitro evaluation of both haemodynamics and durability of bioprostheses, since some of the pericardial valves which had the best haemodynamic performance showed the worst resistance to fatigue-induced failure. A careful selection of the tissue, modification of the stent design and avoidance of a dacron covered frame are suggested to improve long-term durability of biological prostheses.
在体外，使用脉动复制器和疲劳测试系统对二尖瓣生物假体的血流动力学特性和耐用性进行了评估和比较。在模拟静息和运动心率的条件下研究发现，猪异种移植物是所有生物假体中最狭窄的；另一方面，与目前临床上使用的标准猪心包生物假体相比，新一代生物瓣膜在血流动力学方面有明显改善。在每分钟1600至1800次搏动的频率以及80至100 mmHg的关闭压力下进行的耐用性测试表明，Ionescu-Shiley和Edwards心包异种移植物的使用寿命明显长于Hancock和Carpentier Edwards猪瓣膜以及Hancock心包生物假体。心包瓣膜和猪瓣膜在体外和体内的失效模式之间的相关性清楚地表明，机械应力在瓣膜失效中起主要作用。这可能是由于瓣叶运动时组织撞击缝合环裸露的涤纶布而持续受到创伤的结果，或者是小叶弯曲点处出现疲劳的结果。这项研究的结果强调了对生物假体的血流动力学和耐用性进行持续体外评估的重要性，因为一些血流动力学性能最佳的心包瓣膜对疲劳引起的失效表现出最差的抵抗力。建议仔细选择组织、改进支架设计并避免使用涤纶覆盖框架，以提高生物假体的长期耐用性。
