增龄变化对血管移植材料脐带静脉顺应性的影响

背景血管重建术中内径小于6 mm的人工合成血管替代人体小动脉或静脉一直未获得满意的效果,因而目前小动脉及静脉代用品成为亟待解决的问题.目的观察不同胎龄脐带静脉压力-容积关系,为血管移植材料脐带静脉的生物力学性质上提供实验数据.设计非随机对照实验.材料实验于2004-06在郧阳医学院医用生物力学实验室完成,湖北省十堰市太和医院妇产科收集胎龄在24～42周自然流产或分娩的正常胎儿脐带静脉50条(经产妇许可),产妇年龄20～30岁.其中胎龄24～27周8例,28～32周7例,33～36周8例,37周4例,38周5例,39周5例,40周5例,41周4例,42周4例.干预取胎儿脐带50条,测量一段脐带长度(2 cm)并标记两端点后,切下脐带置于生理盐水中.仔细地对脐带静脉进行机械剥离后,将试件两端标记点固定在软组织生物力学试验台上,测定其压力-容积关系,计算出顺应性.主要观察指标不同脐带静脉的压力、容积及顺应性.结果50条脐带全部进入结果分析.①37～40周脐带静脉压力-容积曲线比较接近,而28周,42周脐带静脉压力-容积曲线幅度明显下降,经二次回归分析可见38周胎龄压力-容积曲线回归系数绝对值最大.②脐带静脉顺应性随胎龄增加而增大[24～27周(2.22-±0.34)×10-4mL/(kP·cm),28～32周(3.65±0.46)×10-4 mL/(kPa·cm),33～36周(4.22±0.55)×10-4mL/(kPa·cm),37周(7.63±0.48)×10-4 mL/(kPa·cm),38周(8.32±0.76)×10-4mL/(kPa·cm)],但39周以后又降低[39周(7.61±0.46)×10-4 mL/(kPa·cm),40周(7.53±0.72)×10-4 mL/(kPa·cm),41周(4.13±0.35)×10-4 mL/(kPa·cm),42周(2.25±0.62)×10-4 mL/(kPa·cm)].37～40周脐带静脉的顺应性较相近,而42周及28周以下脐带静脉的顺应性与37～40周比较(F=65.84-86.52,P＜0.01).结论人脐带静脉是动脉移植物的良好替代材料,在移植时除了考虑脐带静脉与宿主动脉相匹配外,还应注意其顺应性与胎龄的关系,实验结果提示,胎龄在37～40周的脐带静脉作为临床应用的移植材料较为理想.

Effects of aging changes on the compliance of human umbilical cord vein as the material for vascular grafting

BACKGROUND: So far it has not achieved satisfactory effects to use synthetic blood vessels (diameter＜ 6 mm) as the substitutes for human small arteries or veins when clinical reconstructive vascular operations are performed. So, study on the substitutes for small arteries and veins has been a problem demanding prompt solution at present.OBJECTIVE: To observe the pressure-volume (P-V) relationship of umbilical cord vein of different gestational ages so as to provide theoretical basis of biomechanical properties for the clinical application of human umbilical cord vein as material for vascular grafting.DESIGN: Non-randomized controlled experiment.PARTICIPANTS: The experiment was completed in the Laboratory of Medical Biomechanics, Yunyang Medical College in June 2004. Umbilical cord veins of 50 normal fetuses were collected on spontaneous miscarriage or labor with the pregnant women's permission by the Department of Obstetrics and Gynecology, Shiyan Taihe Hospital. The gestational age of the fetuses ranged from 24 to 42 weeks and the pregnant women aged 20to 30 years. Among them, 8 cases with gestational age of 24-27 weeks,7cases 28-32 weeks,8 cases 33-36 weeks,4 cases 37 weeks,5 cases 38weeks, 5 cases 39 weeks , 5 cases 40 weeks , 4 cases 41 weeks and 4cases 42 weeks.INTERVENTIONS:Umbilical cord veins of 50 normal fetuses were collected. A 2-cm long segment of each umbilical cord was measured and labeled at both ends. Then they were cut off and put into normal saline (NS). The umbilical veins were carefully stripped from the cord; its two ends were fixed on the biomechanical experiment stand of soft tissues. The P-V relationship of fetal umbilical cord vein was measured, and then the compliance calculated.MAIN OUTCOME MEASURES: Pressure, volume and compliance of different umbilical cord veincurve of pressure-volume relationship of the umbilical cord vein was similar at week 37 to 40 but decreased significantly at week 28 and week 42. After regression analysis twice, it was found that the absolute value of regression vein increased with the increasing of gestational age[24-27 weeks (2.22±0.34)cord vein collected at 37 to 40 weeks of gestational age was similar. When the umbilical cord veins older than 42 weeks or under 28 weeks were compared, there was significant difference in their compliance (F=65.84-86.52, P＜ 0.01).CONCLUSION: Human umbilical cord veins are good substitutes for The relationship between compliance and gestational age. Our studies suggest that the umbilical cord vein, whose gestational ages range from 37to 40 weeks, is a material of choice for the transplantation.