Jansen J, Reul H
Helmholtz-Institute for Biomedical Engineering, Aachen, Germany.
J Med Eng Technol. 1992 Jan-Feb;16(1):27-33. doi: 10.3109/03091909209021954.
To increase durability and decrease calcification tendencies, the reduction of mechanical leaflet stress is of prime importance. In order to achieve this for a three-leaflet valve, the leaflets of a new design of prosthesis (the J-3) are manufactured in a medium open, almost flat shaped position, whereby the stent posts are expanded by a cone-shaped mold. Owing to this design, the leaflets have stable closed and open positions, the transition succeeds with low opening pressure. Valves are manufactured by dip-coating in polyurethane. Hydrodynamic evaluation of this polyurethane valve shows minimum pressure drop and very low energy losses compared with other commercially available valves. Very low shear stresses in the flow field downstream of the valve are observed by laser-Doppler-anemometry. In durability tests, prototypes have reached lifetimes equivalent to 17 years. For comparative testing of durability and biocompatibility, six bioprostheses and seven J-3 valves were implanted in mitral position of growing Jersey calves. While animal tests are encouraging, they also reveal necessary manufacturing improvements.
为了提高耐用性并降低钙化倾向，降低瓣叶的机械应力至关重要。对于三叶瓣瓣膜而言，为实现这一点，一种新型假体（J-3）的瓣叶在几乎平坦的中等开放位置制造，通过锥形模具扩张支架柱。由于这种设计，瓣叶具有稳定的关闭和打开位置，在低开启压力下成功过渡。瓣膜通过浸涂聚氨酯制造。与其他市售瓣膜相比，这种聚氨酯瓣膜的流体动力学评估显示出最小的压降和极低的能量损失。通过激光多普勒测速仪观察到瓣膜下游流场中的剪切应力非常低。在耐久性测试中，原型的使用寿命已达到相当于17年。为了对耐久性和生物相容性进行对比测试，将六个生物假体和七个J-3瓣膜植入生长中的泽西小牛的二尖瓣位置。虽然动物试验令人鼓舞，但也揭示了必要的制造改进。
