Leat M E, Fisher J
Department of Mechanical Engineering, University of Leeds, UK.
Med Eng Phys. 1994 Nov;16(6):470-6. doi: 10.1016/1350-4533(94)90071-x.
A new geometry for the design of polyurethane leaflet heart valves has been investigated. The geometry termed the 'alpharabola' has a radius of curvature that increases from the centre of the leaflet at the free edge towards the base of the valve and perimeter of the leaflet. The hydrodynamic function and leaflet opening characteristics of the new valve design have been compared to a valve with a spherical leaflet geometry using the same material. The pressure and flow required to open alpharabola leaflets in steady flow tests was markedly lower than for spherical leaflets. Under pulsatile flow conditions with the valve leaflets fully open, the pressure drop across the alpharabola and spherical leaflets was similar, but much lower than in a porcine bioprosthesis. High speed photography showed that the alpharabola leaflets opened in less than 30 ms with the leaflet opening initiating in the base of the leaflet where the radius of curvature was larger. The synthetic leaflet valve has demonstrated short term durability in accelerated fatigue tests to 100 million cycles.
一种用于聚氨酯瓣叶心脏瓣膜设计的新几何形状已被研究。这种被称为“阿拉伯抛物线”的几何形状具有这样的曲率半径：从瓣叶自由边缘处的中心朝着瓣膜基部和瓣叶周边方向增大。已使用相同材料，将这种新瓣膜设计的流体动力学功能和瓣叶打开特性与具有球形瓣叶几何形状的瓣膜进行了比较。在稳定流测试中，打开阿拉伯抛物线形瓣叶所需的压力和流量明显低于球形瓣叶。在瓣膜瓣叶完全打开的脉动流条件下，阿拉伯抛物线形瓣叶和球形瓣叶上的压降相似，但远低于猪生物瓣膜。高速摄影显示，阿拉伯抛物线形瓣叶在不到30毫秒内打开，瓣叶打开从曲率半径较大的瓣叶基部开始。这种合成瓣叶瓣膜在加速疲劳测试中已证明在1亿次循环内具有短期耐久性。
