Effect Of Adjuvant Radiotherapy And Chemotherapy On Vascular Graft After Prosthetic Replacement Of The Abdominal Aorta In Canine

Objective:To establish canine models after reconstruction of infrarenal abdominal aorta by expanded Polytetrafluoroethylene (ePTFE) grafts, in order to mimic reconstruction of abdominal aorta after combined resection of malignant tumor and vital vessels which have been involved.Methods:Operations were performed in 40 mongrel canines with the body weight of 8?12 kg. By a median abdominal incision, the infrarenal abdominal aorta was exposed carefully. After intravenous administration of heparin (0.5mg/kg), both proximal and distal sides of the infrarenal abdominal aorta were clamped, thereafter a segment of about 2.5 cm was resected and quickly reconstructed with an ePTFE graft (diameter:6 mm) by running suture. After operation, medical treatment including antibiotics, anticoagulation and anti-platelet measures were routinely carried out.Results:All the surgical procedures were completed successfully. During and after operation,5 cases suffered from chyle vessel injury, operative incision infection, respiratory tract infection or diarrhea, of which 1 case died 5 days postoperatively, and the others recovered quickly. The survive rate is 97.5%(39/40).Conclusions:Reconstruction of infrarenal abdominal aorta by ePTFE grafts is a good method to establish canine models to mimic the settings after combined resection of malignant tumor and vital vessels involved, with a high rate of success, low incidence of complications, stable performance and satisfying quality. This canine model can be used for further researches.Objective:To study the effect of postoperative external fractionated irradiation on the ePTFE vascular grafts in mongrel canine models.Methods:After the infrarenal abdominal aorta was replaced by ePTFE prosthesis graft, twenty-six canine models were randomly divided into radiotherapy group (group F, n=13) and control group (group D, n=13), according to which the postoperative external fractionated irradiation (7Gy×5d) was administrated or not. The animals were sacrificed and graft specimens were harvested at 4 weeks (subgroup F1 and D1) or 12 weeks (subgroup F2 and D2) after radiotherapy. Physiological parameters during radiotherapy were recorded and H-E staining of the neointima inside the grafts, immunohistochemistry test of CD34 and PCNA were carried out.Results:The average body weight of each group decreased more or less (group F:0.8±0.5kg; group D:0.3±0.2kg). Two cases died in group F (2/13,15.4%), while all survived in group D. Inflammation of the tissues around the grafts was more severe in group F, but no evidence of increasing possibility of graft obstruction, infection or anastomotic pseudoaneurysm was observed. There is no statistical significance about difference of the intima thickness between subgroup D1 and F1 (p>0.05), while significant difference exists between subgroup D2 and F2. Except the middle segment of the grafts, no statistical difference exists on the coverage of vascular endothelial cells (percentage of CD34+ cells) between group F and group D (P>0.05). Comparing to group D, lower expression of PCNA in group F was observed, especially in subgroup F2 (p<0.05).Conclusions:Postoperative external fractionated irradiation (7Gy×5d) after prosthetic vessel replacement of abdominal aorta may result in severe inflammation of tissues around the grafts, but does not increase the incidence of graft obstruction, infection or anastomotic pseudoaneurysm in 12 weeks. It does not significantly influence the growth and coverage of vascular endothelial cells, but can inhibit neointima proliferation and PCNA expression inside the grafts.Chapter 3. Effect of Adjuvant Chemotherapy on Vascular Graft After Prosthetic Replacement of the Abdominal Aorta in CanineObjective:To study the effect of postoperative combined intravenous chemotherapy on the ePTFE vascular grafts in mongrel canine models.Methods:After the infrarenal abdominal aorta was replaced by ePTFE prosthesis graft, twenty-six canine models were randomly divided into chemotherapy group (group H, n=13) and control group (group D, n=13), according to which the postoperative intravenous combined chemotherapy (5-FU:10mg/kg, cis-platinum:1mg/kg) was administrated or not. The animals were sacrificed and graft specimens were harvested at 4 weeks (subgroup H1 and D1) or 12 weeks (subgroup H2 and D2) after chemotherapy. Physiological parameters during chemotherapy were recorded, and H-E staining of the neointima inside the grafts, immunohistochemistry test of CD34 and PCNA were carried out and analysed. Results:The average body weight decreased in each group (group H: 1.0±0.7kg; group D:0.3±0.2kg). Three cases died in group H (3/13, 23.1%), while no one died in group D. No evidence of increasing the possibility for blood vessel prosthesis obstruction, infection or anastomotic pseudoaneurysm was observed, but inflammatory response of the tissues around the grafts was more obvious in group H. Small amount of mural thrombus formation were observed in some grafts (H1: 2/5; H2:3/5; D1:0/6; D2:2/7). There is no statistical significance about the intima thickness difference between subgroup D1 and F1 (p>0.05), or between subgroup D2 and F2. No statistical difference exists on the coverage of vascular endothelial cells (percentage of CD34+cells) between group H and group D, except the very middle segment of the grafts in subgroup D1 and H1. No statistical difference exists on the expression of PCNA between group F and D (p>0.05). However, in each subgroup, the percentage of CD34+ cells and expression of PCNA were the lowest in the middle of the grafts.Conclusions:Postoperative combined intravenous chemotherapy (5-FU and cis-platinum) after prosthetic vessel replacement of abdominal aorta may result in obvious inflammatory response of tissues around the prosthesis, without increasing the incidence of graft obstruction, infection or anastomotic pseudoaneurysm in 12 weeks. It may increase the possibility of mural thrombus formation, while not significantly influence the vascular endothelial cells coverage, neointima proliferation or PCNA expression inside the grafts. Further researches are needed for long-term results.