Anastomotic Stenosis is a Cause of Intimal Hyperplasia at the Middle Portion of Arterial Graft

背景：动脉移植物已成为冠状动脉搭桥手术的首选材料。然而，动脉移植物的通畅取决于吻合的质量，吻合口狭窄是搭桥失败的原因之一。吻合口狭窄不仅在吻合口附近，而且在移植物的中间部分也可能通过改变内皮功能导致内膜增生（IH）。方法与结果：将新鲜制备的RT11大鼠胸主动脉移植至同种大鼠腹主动脉。对近端或远端吻合部位进行绑扎，使管腔大小为原移植物的50-75%。近端狭窄（PS）组（0.78+/-0.18）和远端狭窄（DS）组（0.53+/-0.03）与无狭窄（NS）组（0.19+/-0.09）相比，吻合口附近宿主腹主动脉流速（M/m2）与移植物中部的差异显著（p < 0.05）。PS组（48.3+/-6.7）和DS组（21.3+/-4.3）明显高于NS组（6.0+/-2.5）。各组狭窄程度与IH程度呈显著负相关。然而，在吻合口狭窄程度相同的情况下，PS产生的IH明显高于DS。免疫组化分析显示，PS组和DS组一氧化氮合酶3型（NOS3）阳性内皮细胞数量明显少于NS组。PS组nos3阳性内皮细胞明显少于PD组。结论：这些结果表明，动脉移植物的近端或远端吻合口狭窄是移植物中部IH的重要决定因素。然而，在吻合口狭窄严重程度相同的情况下，PS的IH程度比PD更突出。内皮细胞的一氧化氮合成受损与血流速度降低和其他未确定的机械力的调节有关，可能参与了这一发病机制。少

Background : Arterial grafts have become a choice of materials for coronary artery bypass surgery. However, patency of arterial grafts depends on the quality of anastomosis, and anastomotic stenosis is a cause of bypass failure. Anastomotic stenosis alterflow conditions within the grafts not only at the proximity of anastomosis but also at the middle portion of the graft that may leads to intimal hyperplasia (IH) by modifying endothelial functio. Methods and Results : Freshly prepared thoracic aorta from RT11 rats were transplanted to the abdominal aorta of the same strain. Proximal or distal anastomotic site was banded to create a luminal size of 50-75% of the original graft. The difference in flow velocity (M/m2) between the host abdominal aorta at the proximity of the anastomosis and the middle portion of the graft was significantly greater in proximal stenosis (PS) group (0.78+/-0.18) and in distan stenosis (DS) group (0.53+/-0.03) than in no-stenosis (NS) group (0.19+/-0.09). IH a … More s assessed by the ratio of intimal/medial are (%) at the middle portion of the graft 30 days after surgery was significantly reater in PS group (48.3+/-6.7) and in DS group (21.3+/-4.3) than in NS group (6.0+/-2.5). There was a significant negative correlation between the severity of stenosis and the degree of IH in each group. However, PS produced significantly greater IH compared with DS when the degree of anastomotic stenosis was identical. Immunohistochemical analysis revealed significantly less number of nitric oxide synthase type 3 (NOS3)-positive endothelial cells in PS and DS groups than in NS group. NOS3-positive endothelial cells were significantly less in PS group tha in PD group.Conclusions : These results suggest that anastomotic stenosis of arterial grafts either proximal or distal is an important determinant for IH at the middle portion of the graft. However, the degree of IH is more prominent in PS than in PD when the severity of anastomotic stenosis is identical. Impaired nitric oxide synthesis by endothelial cells associated with reduced flow velocity and modulation of other undertermined mechanical forces may be involved in this pathogenesis. Less