Experimental Study of Staged Increase in Shunt Flow for Systemic to Pulmonary Arterial Shunts using vascular grafts

我们实验了一种新的技术，即用可吸收材料狭窄血管移植物，并减少分流，以防止使用血管移植物进行体动脉到肺动脉分流术后急性期的过度血流。在9只比格犬身上建立了使用5 mm膨胀聚四氟乙烯(EPTFE)管的改良Blalock-Taussig分流术。用聚二氧杂环己酮可吸收夹夹住分流管，减少分流流量。术后4周，将分流通畅的犬分为A、B两组。A组采用球囊血管成形术扩张受压部位。分流术后12周处死动物，取出移植物。B组：处死犬，摘除移植物。除上述三组外，C组(n=3)在分流手术时未夹住分流管。分流术后12周处死动物，取出移植物。A…分流术后4周以上，3条犬分流道血流量分别减少30.1%、40.7%和44.6%。而流量减少66.8%~85.4%的6只犬分流管通畅。A组夹闭分流管后，分流流量下降率分别为30.1%、40.7%和44.6%。球囊成形术使受压部位完全扩张，分流流量增加率分别为54.1%、33.2%和30.7%。A组移植血管光镜下可见管腔被纤维蛋白和纤维组织组成的假性内膜覆盖。B组夹伤部位覆盖纤维蛋白层，夹闭部位有白细胞。C组移植血管中段被纤维纤维组织构成的假性内膜覆盖。A组和B组的假性内膜增厚程度均大于C组。结论：使用该技术阶段性增加分流流量是可行的，可防止使用血管移植物进行体动脉到肺动脉分流后的过度分流。然而，需要进一步的研究来预防假性内膜增生和延迟血管移植物的愈合机制。较少

We experimented with a new technique in which the vascular graft was stenosed by an absorbable material and the shunt flow was decreased to prevent excessive flow in the acute postoperative stage for systemic to pulmonary arterial shunts using vascular grafts.Left modified Blalock-Taussig shunts using 5-mm expanded polytetrafluoroethylene (ePTFE) tubes were created in 9 beagle dogs. The shunt was pinched by polydioxanone absorbable clips and the shunt flow was decreased. At 4 weeks after the operation, the dogs whose shunts had been patent were classified into group A or B.In group A,the pinched site was dilated by means of balloon angioplasty. At 12 weeks after the shunt operation, the dogs were sacrificed and the grafts were removed. In group B,the dogs were sacrificed and the grafts were removed. In addition to these groups, in group C (n=3), the shunt was not pinched at the shunt operation. The dogs were sacrificed and the grafts were removed at 12 weeks after the shunt operation.A … More t 4 weeks after the shunt operation, three dog's shunts whose flow had been decreased of 30.1,40.7 and 44.6% were occluded. But six dog's shunts whose flow had been decreased of 66.8 to 85.4% were patent. Three of the six dogs were classified into group A.In group A,when the shunts were pinched by clips, a rate of decrease in the shunt flow were 30.1,40.7 and 44.6%, respectively. Balloon angioplasty dilated the pinched sites completely and a rate of increase in the shunt flow were 54.1,33.2 and 30.7%, respectively. In group A,light microscopic examination of the grafts showed that the lumens were covered with a pseudointima organized by fibrin and cellulofibrous tissues. In group B,these sites were covered with a fibrin layr with leukocytes at the pinched sites. In group C,the lumens were covered with a pseudointima organized by cellulofibrous tissues in the middle of each graft. The extent of pseudointimal thickening was greater in groups A and B than in group C.In conclusion, a staged increase in shunt flow is feasible using this technique and prevents excessive shunt flow after systemic to pulmonary arterial shunts using vascular grafts. However, further investigation is needed to prevent pseudointimal hyperplasia and a delay in healing mechanism of vascular grafts. Less