血管移植中不同段脐带静脉的生物力学特性研究

背景临床施行血管重建术,内径小于6mm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的研制成为亟待解决的问题.目的为脐带静脉作为小口径移植材料的临床应用提供理论依据.设计非随机分组对照研究.地点和对象实验在郧阳医学院解剖学教研室完成,对象为湖北省十堰市太和医院妇产科收集胎龄在3740周自然分娩正常胎儿脐带静脉20例,产妇年龄在20～30岁.干预取胎儿脐带静脉20例,依胎盘端为近端,胎儿端为远端分为近、中、远3段.在生物软组织力学试验机上测定近、中、远段脐带静脉的压力-直径关系,计算出弹性模量.横断取材,冷冻切片,苏木精-伊红法染色,用计算机图像分析系统测量其几何形态学指标.主要观察指标脐带静脉的血管各相同性增量弹性模量(Einc)、血管压力-应变弹性模量(Ep)、血管容积弹性模量(Ev)、直径和壁厚.结果近、中、远段脐带静脉的Einc,Ep和Ev均随压力的上升而增大,近段3种弹性模量(Einc26.98±3.21,Ep16.58±2.12,Ev8.31±2.35)均低于远段(Einc33.20±4.21,Ep119.45±2.87,Ev9.71±1.32)(F=95.74～126.52,P＜0.05),由近段到远段呈增大趋势.中膜厚度[(0.30±0.05)mm,(0.24±0.03)mm]及直径[(3.07±0.12)mm,(2.30±0.13)mm]值从近段到远段逐渐减小(F=12.76,P＜0.01).结论脐带静脉作为小口径动脉移植的替代材料是可行的,在血管移植时,应注意选择不同段脐带静脉,使作为移植材料的脐带静脉与宿主血管材料间的生物力学特性尽量相近,以提高移植血管的远期通畅率.

Biomechanicalcharacteristics of different segments of human umbilical cord vein in vascular grafts

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 provide a theoretical basis for the clinical application of umbilical cord veins used as small-caliber grafts.DESIGN: A nourandomIzed grouping and controlled study was conducted.SETTING and PARTICIPANTS: The experiment was completed in the Department of Anatomy, Yunyang Medical College. Umbilical cord veins of 20 normal fetuses of spontaneous labor were collected by the Department of Obstetrics and Gynecology, Taihe Hospital in Shiyan, Hubei Province. The fetuses aged 37 -40 weeks old and the parturient aged 20 -30 years old.INTERVENTIONS: Umbilical cord veins of the 20 fetuses were used and the placenta ends were treated as proximal ends while the fetal ends as distal ends. The fetal ends were divided into three segments: proximal segments,middle segments and distal segments. The relationship between the pressure of umbilical cord veins of proximal, middle and distal segments and the diameters was measured on the biomechanical experiment stand for soft tissues, and then the elastic modulus was calculated. The materials were transversely extracted,refrigerated and sliced up before HE staining. The geometrical morphology indexes were measured by the computer image analysis system.MAIN OUTCOME MEASURES: Incremental elastic modulus(Einc);pressure-strain elastic modulus (Ep); volume elastic modulus( Ev); diameter;wall thickness.RESULTS: Einc, Ep and Ev of umbilical cord veins of proximal segments,middle segments and distal segments increased with the pressure elevated. The three kinds of elastic modulus of proximal segments( Enic: 26.98 ±3.21, Ep: 16.58 ±2. 12, Ev: 8.31 ±2. 35) were all lower than those of distal segments( Einc: 33.20 ±4.21, Ep: 119.45 ±2. 87, Ev: 9.71 ± 1.32)(F=95.74-126.52, P ＜0.05) and an increase tendency was showed from proximal segments to distal segments. Media thickness[ (0.30 ± 0. 05)mm, (0.24 ± 0.03) mm] and the diameters[ (3.07 ± 0. 12) mm, (2.30 ±0. 13) mm] decreased gradually from proximal segments to distal segments (F= 12.76, P ＜0.01).CONCLUSION: It is feasible to use umbilical cord veins as substitutes for the transplantation of small-caliber arteries. On vascular grafting, different segments of umbilical cord veins should be chosen cautiously so that the biomechanical characteristics of umbilical cord veins used as grafts could be accorded with those of most blood vessels as far as possible so as to increase the long-term patency rate of transplanted blood vessels.