Bekler Halil Ibrahim, Rosenwasser Melvin P, Akilina Yelena, Bulut Güven
Department of Orthopedics and Traumatology, Medicine Faculty of Yeditepe University, Ankarayolu, Kozyataği, Istanbul, Turkey.
Acta Orthop Traumatol Turc. 2010;44(2):157-61. doi: 10.3944/AOTT.2010.2298.
Autologous interpositional vein grafts are used in peripheral arterial bypass procedures. Sudden exposure of vein grafts to arterial blood pressure is associated with increased wall tension leading to overdistension of the graft and changes in flow patterns. Overdistension of vein grafts often results in anastomotic leaks, thrombosis, and loss of patency. This study was designed to evaluate the use of a biodegradable collagen cover as a means of preventing overdistension of venous bypass grafts in a rat model.
Twenty-two Sprague-Dawley female rats weighing 250-350 g were randomly assigned to two groups: study group (n= 15) and control group (n=7). In all the rats, a 10-mm segment of the left femoral vein was harvested and used as a graft in repair of a right femoral artery injury. Following this procedure, control rats remained untreated. After completion of the femoral artery repair in the study group, the graft was wrapped with a collagen cover of appropriate length (NeuraWrap Nerve Protector) and sutured to form a tube around the vein graft. At the end of the procedure, the intensity and duration of bleeding, and vessel patency were recorded and the proximal and distal arterial segments were examined by Doppler ultrasonography. All observations and measurements were repeated at 1 and 2 hours after surgery. After the second hour, all the rats were sacrificed and vein graft samples with the arterial portions were removed for histological study.
After removal of the vascular clamps of the control group, a sudden distension was observed in all the vein grafts. In this group, bleeding at the anastomosis site lasted for 1 to 3 minutes and was followed by ballooning of the grafts. In the study group, however, none of the samples exhibited distension and ballooning. There was no bleeding in 11 samples at all, and bleeding time was less than one minute in the remaining four samples. In the control group, only one graft was patent at two hours, one of the grafts was occluded after only three minutes. In the study group, all the grafts were patent and no thrombosis was noted. The mean blood flow velocity of the control group measured at 0 hour by Doppler ultrasonography was 0.93+/-0.33 cm/sec in the proximal artery, and 0.73+/-0.44 cm/sec in the distal artery. The mean blood flow velocities in the proximal and distal arteries of the study group were as follows, respectively: at 0 hour: 0.45+/-0.27 and 0.46+/-0.22 cm/sec; at 1 hour: 0.40+/-0.22 and 0.62+/-0.40 cm/sec; and at 2 hours: 0.55+/-0.22 and 0.64+/-0.37 cm/sec.
Prevention of overdistension of vein grafts with the use of an external cover decreases anastomotic leaks, protects the intimal media, maintains blood flow, reduces the incidence of thrombosis, and thus provides a higher patency rate.
自体静脉移植常用于外周动脉搭桥手术。静脉移植物突然暴露于动脉血压下会导致壁张力增加，进而导致移植物过度扩张和血流模式改变。静脉移植物过度扩张常导致吻合口漏血、血栓形成和通畅性丧失。本研究旨在评估在大鼠模型中使用可生物降解的胶原蛋白覆盖物作为预防静脉搭桥移植物过度扩张的一种方法。
将22只体重250 - 350 g的雌性Sprague-Dawley大鼠随机分为两组：研究组（n = 15）和对照组（n = 7）。在所有大鼠中，取一段10 mm长的左股静脉作为移植物用于修复右股动脉损伤。此操作后，对照组大鼠不做处理。研究组完成股动脉修复后，用适当长度的胶原蛋白覆盖物（NeuraWrap神经保护器）包裹移植物，并缝合形成围绕静脉移植物的管子。手术结束时，记录出血强度和持续时间以及血管通畅情况，并用多普勒超声检查近端和远端动脉段。所有观察和测量在术后1小时和2小时重复进行。2小时后，处死所有大鼠，取出带有动脉部分的静脉移植物样本进行组织学研究。
对照组去除血管夹后，所有静脉移植物均出现突然扩张。该组吻合口部位出血持续1至3分钟，随后移植物膨胀。然而，研究组中没有样本出现扩张和膨胀。11个样本完全没有出血，其余4个样本出血时间少于1分钟。对照组中，2小时时只有1个移植物保持通畅，其中1个移植物仅3分钟后就闭塞了。研究组中，所有移植物均保持通畅，未发现血栓形成。对照组在0小时通过多普勒超声测量的近端动脉平均血流速度为0.93±0.33 cm/秒，远端动脉为0.73±0.44 cm/秒。研究组近端和远端动脉的平均血流速度分别如下：0小时：0.45±0.27和0.46±0.22 cm/秒；1小时：0.40±0.22和0.62±0.40 cm/秒；2小时：0.55±0.22和0.64±0.37 cm/秒。
使用外部覆盖物预防静脉移植物过度扩张可减少吻合口漏血，保护内膜中层，维持血流，降低血栓形成发生率，从而提供更高的通畅率。
