Novel Esophageal Stent For Treatment Of Anastomotic Leakage:an Experimental Study In Rabbits

Objective: To assess the safety and effectiveness of the biodegadeble stent in the management of esophageal anastomotic leakage.Methods: All operations were performed under conscious sedation,with intravenous injection of pentobarbital sodium(1ml/kg)for general anesthesia.A total of 20 rabbits,weighing between 2-3 kg,underwent esophageal incision anastomosis and insert rubber hose which outer diameter is 8F,as nutrient canal,resulting in experimental esophageal anastomotic fistula.fifteen rabbit models were randomly divided into A?B?C groups at one week after the esophageal incision anastomosis,a control group(A group,control,no stent insertion,n=5),a plastic stent group(B group,n=5)and biodegradable stent group(C group,n=5).Esophagography was performed under general anesthesia every week to evaluate the stent position until 8 weeks after the stent placement.Then all stent extraction was performed.8 weeks after stent implantation,air embolism is executed with the rabbits to pathology observation.HE and VB staining to study the fistula part formation and structure of organization,compare the stoma site changes of extracellular matrix.A pathologist was blinded to the animal randomization and treatment procedure to review all the specimens and conduct the analysis.Results: 1.Esophageal anastomotic fistula model was successfully established in 17 rabbits after esophageal incision anastomosis,as indicated by gastrografin esophagram examination and 3 rabbits died of infection and malnutrition.2.There was no esophageal perforation occurred during the stent insertion.All stents were successfully covered at the fistula,esophagram showed that gastrografin through the esophagus smoothly and no leakage.3.No immediate stent migration occurred after stent placement in the all groups.After 8 weeks of placement,B group of rabbit esophageal stents without displacement,there were 3 cases of decomposition,and the stents into the stomach about 5-8weeks in C group.4.all the rabbits of A group died at 4-6 weeks after modeling,and the weight was decreased significantly.After dissection,a large amount of gastric contents and fistula were found around esophageal fistula.at B group,2 rabbits died(1 fistula was not closed with severe infection,1 refused to eat and drinking led to systemic exhaustion),the mortality rate was 2/5.at C group,there was 1 death(1 refused to eat and drinking,led to systemic exhaustion),the mortality rate was 1/5,the difference between the two groups was not statistically significant(P> 0.05).at B group,3 rabbits' fistula were completely closed(closing rate 3/5),C group had 4 animals,anastomotic fistula completely closed(closing rate of 4/5).There was no significant difference between the two groups(P> 0.05).5.Tissue reaction were compared between B group and C group.At B group,Both ends of the stent embedded into the esophageal wall,and the hyperplasia was obvious,The main body of the stent was closely connected with the esophageal and removal difficulty.However,after 8 weeks of stent implantation,the anatomical observation of the undecomposed stents showed that there were slightly proliferated at both ends of the stent of the esophageal,and the scaffolds were decomposed,broken and incomplete,part of stents monofilament were still connected.6.B group fistula site of the esophageal wall tissue HE staining found uneven thickness of squamous epithelium,uneven arrangement,local squamous epithelial loss,local squamous cell necrosis.There is a hyperplasia and protrusion,and the hyperplasia is mainly composed of connective tissue and squamous epithelium.In the cortical connective tissue,there is a large number of neutrophils and focal lymphocyte infiltrates.The myofibrinolysis atrophy of muscle layer is replaced by connective tissue.C group HE staining showed squamous epithelium thickness is more uniform,showing a proliferation and protrusion,hyperplasia of the outer layer of uniform thickness of the squamous epithelium,mainly for connective tissue and a small amount of muscle fibers;no obvious inflammatory response.EVG staining suggested that B group,C group fistula parts are visible a small amount of regular cord-like collagen fibers filled and closed fistula.Conclusions: Esophageal biodegradable stents could provide reliable support,with acceptable migration rates and provide a new method for treatment of anastomotic leaks.