胎儿脐静脉移植材料的应力松弛特性

Stress relaxation properties of fetal umbilical cord vein grafts

背景:人脐静脉是动脉移植物的良好替代材料,在移植时除了考虑脐静脉与宿主动脉相匹配外,还应注意其顺应性。目的:检测胎儿脐静脉近胎盘段和远胎盘段试样的应力松弛特性。方法:取22-28岁、胎龄38-40周、自然分娩产妇的正常胎儿脐静脉近胎盘段和远胎盘段各10个试样,在电子万能实验机上进行应力松弛实验,在(36.5±0.5)℃的温度场下,以0.1%/s的应变增加速度对试样施加应变,设定时间为7200s。采集100个数据,采用归一化分析的方法计算两组试样的归一化应力松弛方程。结果与结论:脐静脉近胎盘段组7200s应力下降了0.275MPa,脐静脉远胎盘段组7200s应力下降了0.203MPa,两组7200s应力下降量差异有显著性意义(P<0.05)。两组试样应力松弛曲线是以对数关系变化的,并且胎儿脐静脉近胎盘段和远胎盘段具有不同的应力松弛特性。

BACKGROUND：Human umbilical cord vein can serve as a good substitute for arterial grafts. Compliance of graft materials is a key problem during the transplantation expect for the matching between the umbilical cord vein and host’s artery. OBJECTIVE：To detect the stress relaxation properties of fetal umbilical vein samples proximal and distal to the placenta. METHODS：Fetal umbilical vein samples at the gestational age of 38-40 were taken from spontaneous delivery parturient women aged 22-28 years. Ten proximal placenta segments and 10 distal placenta segments were taken and placed on the electronic universal testing machine to do the stress relaxation test at （36.5±0.5） ℃. The strain was applied to the samples at a strain increases speed of 0.1%/s, and the setting time was 7 200 seconds. Total y 100 data were col ected;and then, the normalized analysis method was employed to calculate the normalized stress relaxation equation. RESULTS AND CONCLUSION：The stress at 7 200 seconds was decreased by 0.275 MPa in the proximal placenta segment group and 0.203 MPa in the distal placenta segment group. There was a significant difference between the two segment samples （P〈0.05）. The stress relaxation curves of the two groups were changed with logarithmic relationship, and the proximal placenta segment and the distal placenta segment of fetal umbilical cord vein had different stress relaxation properties.