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Development of a Internationally acceptable fatigue test system for prosthetic heart valve

开发国际认可的人工心脏瓣膜疲劳测试系统

基本信息

批准号：
06557073
负责人：
UMEZU Mitsuo
金额：
$ 5.82万
依托单位：
Waseda University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-06557073/
关键词：
heart valve accelerated fatigue test durability Jellyfish valve creep effect impact force FEM analysis Young's modulus 耐久試験総負荷 Jelly-fish弁弁選択基準循環シミュレータ僧帽弁人工弁置換

项目摘要

The purpose of this study is to establish an internationally-acceptable methodology of fatigue testing for prosthetic heart valves, based on the improvement process of a Chinese-made accelerated fatigue test apparatus. This test system had four parallel water cylinders, in which valves were incorporated. Open and closing motion of each valve was controlled at a repetition speed of 10-20 Hz with a displacement of 1-2mm. The Jerryfish (JF) valve was used in this study. It had the longest implantation record in animal trials. In this case, the polyurethane membrane with the thickness of 50-70 mum was ruptured due to a creep effect observed at the middle portion between two spokes after 300days in goat.First of all, in vitro fatigue test machine has been innovated in order to reproduce the above mentioned in-vivo fatigue test results. Dynamic conditions which enabled the identical forces between accelerated and normal cycles were determined : maximum load during valve closure was 5.2N (inc … More reased by 20% to the normal), and impulse was 2.5*10^<-2>N・s. Under this condition, valves were ruptured for 1.0*10^7 cycles, but no distinct creep was noticed. Secondary, a temperature of the test-fluid was changed from 20ﾟC to 50ﾟC,expecting a creep effect to the membrane shape. Change in shape of the membrane was observed after 3.2*10^6 cycles, however, its distortion value was only 50% of the animal experimental results. For the next step, a material of the membrane was changed from polyurethane to polystirene to achieve bigger change in shape. As a result, the identical distortion level was successfully reproduced, but a location of the ruptured area was different between in vitro and in vivo results. In order to clarify the above mentioned difference, FEM analysis was performed. The calculated result exhibited that there are three major areas of the maximum elastic strain between two spokes. Moreover, it was confirmed that the ruptured areas observed by both in vitro/in vivo results could be fully superimposed to the areas of the calculated maximum elastic strain.Further investigation should by carried out to determine more reliable methodology for fatigue testing, based on the in vitro and FEM analysis data. Less

本研究的目的是在对国产加速疲劳试验机进行改进的基础上，建立一种国际通用的人工心脏瓣膜疲劳试验方法。该测试系统有四个平行的水缸，其中装有阀门。每个瓣膜的开启和关闭运动控制在10~20赫兹的重复速度，位移为1~2 mm。本研究使用的是JerryFish(JF)阀。它是动物试验中植入记录最长的。在这种情况下，山羊在300天后，由于观察到两个辐条之间的中间部分的蠕变效应，导致厚度为50-70微米的聚氨酯薄膜破裂。首先，为了再现上述体内疲劳试验结果，对体外疲劳试验机进行了改进。确定了使加速循环和正常循环之间的作用力相同的动态条件：阀门关闭时的最大载荷为5.2N(Inc.…脉冲值为2.5×10~(-2)N·S。在此条件下，瓣膜破裂了1.0×10~(-7)次，但没有明显的蠕变现象。其次，试验液的温度从20ﾟC改变到50ﾟC，期望对膜的形状产生蠕变效应。3.2×10~(-6)循环后，膜形态发生改变，但其变形值仅为动物实验结果的50%。下一步，将膜的材料由聚氨基甲酸酯改为聚苯乙烯，以实现更大的形状变化。结果，成功地复制了相同的扭曲程度，但体外和体内结果中破裂区域的位置不同。为了澄清上述差异，对其进行了有限元分析。计算结果表明，轮辐之间存在三个主要的最大弹性应变区域。此外，还证实了由体外和活体结果观察到的断裂区域可以完全叠加到计算的最大弹性应变区域。基于体外和有限元分析数据，需要进行进一步的研究以确定更可靠的疲劳试验方法。较少