Köhler J, Wirtz R
RWTH Aerodynamic Institute, Aachen, Germany.
Int J Artif Organs. 1991 May;14(5):290-4.
The aim of the project was to develop laboratory test devices for studies of the cinematics and sticking behaviour of technical valve protheses. The second step includes testing technical valves of different types and sizes under static and dynamic conditions. A force-deflection balance was developed in order to load valve rims by static radial forces until sticking or loss of a disc (sticking- and clamping-mould point) with computer-controlled force deflection curves. A second deflection device was developed and used for prosthetic valves in the aortic position of a pulsatile mock circulation loop with simultaneous video-cinematography. The stiffness of technical valve rims varied between 0.20 (St. Jude) and about 1.0 N/micron (metal rim valves). The stiffness decreased significantly with increasing valve size. Sticking under pulsatile flow conditions was in good agreement with the static deflection measurements. Hence, valve sticking with increasing danger of thrombus formation is more likely with a less stiff valve rim. In the case of forces acting perpendicularly to the pendulum axis, the clamping mould-point of the valve can be reached, followed by disc dislodgement.
该项目的目的是开发用于研究技术瓣膜假体的运动学和粘连行为的实验室测试装置。第二步包括在静态和动态条件下测试不同类型和尺寸的技术瓣膜。开发了一种力-挠度平衡装置，以便通过静态径向力加载瓣膜边缘，直到圆盘出现粘连或脱落（粘连和夹紧模具点），同时记录计算机控制的力-挠度曲线。开发了第二种挠度装置，并将其用于脉动模拟循环回路主动脉位置的人工瓣膜，同时进行视频摄影。技术瓣膜边缘的刚度在0.20（圣犹达瓣膜）至约1.0 N/微米（金属边缘瓣膜）之间变化。刚度随着瓣膜尺寸的增加而显著降低。脉动流条件下的粘连与静态挠度测量结果高度一致。因此，瓣膜边缘刚度越小，发生粘连并形成血栓的风险就越高。在垂直于摆轴的力作用下，可能会达到瓣膜的夹紧模具点，随后圆盘会发生移位。
