The Effect Of Post-operative Irradiation With High Dose External Beam Radiation On The Neointima Of Vascular Graft After Inferior Vena Cava Prosthetic Vessel Replacement In Canine

ObjectiveTo observe the effect of post-operative irradiation with high dose on the neointima proliferation of vascular graft,as well as covering of vascular endothelial cell to the neointima after inferior vena cava prosthetic vessel replacement.MethodsSixteen dogs were randomly divided into two groups including the radiotherapy group and the control group.Inferior vena cava replacement with a 6-mm ePTFE vascular graft was carried out in each group.The radiotherapy group was irradiated with a dose of external radiation(35Gy) on the ePTFE vascular and the distal end-to-side anastomosis at two weeks after surgery while the other not.All the dogs were sacrificed at eight weeks after operation for histological and immunohistochemical examination of the neointima of the venous prosthetic vascular graft and observe the coverage of vascular endothelial cell of the venous prosthetic vascular graft.Results1.All dogs of the control group survived.2.Eight cases of radiotherapy group and 6 cases of control group patency of artificial blood vessels are good.Apart from two cases in the control group were infection,the radiotherapy group artificial vascular patency rate is 8/8,the control group patency rate is 6/8.3.Histological examination shows that intact neointima had formed completely in 8 cases in the radiotherapy group and 6 cases in the control group.4.The thickness of neointimal of vascular prosthesis was measured. The result shows that the intimal thickness of the proximal anastomosis (610.69±32.90μm),the middle of the vascular graft(530.51±32.14μm)and the distal anastomosis(544.52±41.99μm)were significantly smaller in radiotherapy groupthan in control group(753.39±10.36μm,636.55±20.23μm,710.39±30.92μm)(all P＜0.01).The neointima near the proximal anastomosis(753.39±10.36μm) was significantly thicker than the middle of the vascular graft(636.55±20.23μm ) in the control group(P＜0.01).5.The PCNA proliferation in radiotherapy group(45.1%±7.5%) was significantly less than control group(56.3%±7.8%) at the proximal anastomosis(P＜0.01).In the radiotherapy group,the PCNA proliferation at the middle of vascular graft(29.5%±4.3%) was significantly less than the proximal anastomosis(45.1%±7.5%)(P＜0.01). In the control group,near the distal anastomosis(38.9%±8.1%)was significantly less than near the proximal anastomosis(56.3%±7.8%)(P＜0.01);And that in the middle of vascular graft(34.9%±6.5%)was significantly less than at the proximal anastomosis(56.3%±7.8 %)(P＜0.01).6.The difference of the number of vascular endothelial cells in both groups did not reach statistical significance.Conclusions1.No disunion,rupture was found at the anastomosis of the venous prosthetic vascular graft after postoperative radiotherapy at a dose of 35 Gy in our study.2.Postoperative external segmental radiotherapy at the dose of 35 Gy does has no negative effect in the patency rate of prosthetic vascular graft.3.Postoperative external segmental radiotherapy at the dose of 35Gy can inhibit the intima hyperplasia and PCNA expression.4.Postoperative external segmental radiotherapy at the dose of 35Gy doses not affect the vascular endothelial cell coverage rate obviously.