Animal Experimental Study Of The Treatment Of Esophageal Stricture With A New Decomposable Esophageal Stent

PartⅠThe establishment of a esophageal benign stricture rabbit modelObjective:To establish a rabbit model of esophageal benign stricture,to to do the groundwork for the decomposable esophageal stent research.Methods:Thirty-five rabbits weighing 3.0±0.5kg were used as experimental animals.Each rabbit was weighed,anesthetized by intravenous injection of pentobarbital sodium(30mg/kg),and placed in a left recumbent position.A #10 Foley plastic catheter was passed into inferior segment of the esophagus,and then inflate the saccule(15cm inferior to the maxillary incisors).1ml 4%sodium hydroxide was injected above the saccule,saved 30s,then deflate the saccule,20ml water was slowly injected over 1 minute to wash out the esophagus.Esophagographies were made to evaluate the model,the successful model standard:The minimal diameter of the constrictive segment measured by esophagography is smaller than half of the maximal diameter of the dilated segment.Two rabbit models were evaluated by utra-slim gastroscope and histological analysis at 2^th week after alkaline injury.Results:Esophagography showed that stricture formed in inferior segment of the esophagus,and the proximal lumen dilated,contrast agent could go through the constrictive segment,but not smoothly.At 2^th week after alkaline injury,32 in 35 rabbits reached the model standard.The utra-slim gastroscopy showed that scar formed in inferior segment of esophagus(15cm inferior to the maxillary incisors),so that the esophagus lumen narrowed,and the endoscope couldn't go through.Hyperaemic section about 1.5-2.0cm long 2-3cm away the cardia was revealed after rabbits' esophagus was dissected,but the outer layer was smooth.After esophagus was splitted longitudinally,the inner layer was rough and ulcerative scar shaped in inferior segment,and the tube wall became thicker than other areas.Histological analysis showed that partial ulceration,fibrosis,and inflammation in epithelium,submucosa and superficial muscular layers,slight inflammation in deep muscular layer.Conclusion:The alkaline injury method assisted with Foley's tube can cause regional cauterization.This is a good method of establishing esophageal benign stricture.PartⅡThe therapeutic effect of a decomposable esophageal stent on esophageal benign stricture in the rabbit modelObjective:To observe the therapeutic effect of decomposable esophageal stent on esophageal benign stricture model,and the decomposability in rabbit.Methods:Thirty rabbit models were randomly divided into A,B,C groups.No esophageal stents were inserted in Group A rabbits,The common esophageal stents and the new decomposable esophageal stents were inserted into Group B and C rabbits at 2^th week after alkaline injury,respectively.The stents' location and shape were detected by ultra-slim gastroscope and X-ray examination.At 8^th week after stents implantation,rabbits were killed,and esophagus were dissected to observe.Results:Five rabbits in group A died between 4 and 6 weeks after alkaline injury.The stents in group B rabbits remained in position for the full study period,but one rabbit died at 6^th week after stent implantation.Seven stents in group C rabbits decomposed and immigrated into stomach at 5^th and 6^th week after stent implantation,and no death happened in group C.When the rabbits in Group A were dissected,there was some fluid,no solid food in their stomach,perhaps it's related to the worse stricture which ulcerative scar caused.In Group B,the hyperplasia both sides of the stent was so obvious that the stent couldn't been taken out easily,and in the natural dead one,we could find some small perforation both sides of the stent.In Group C,slight hyperplasia emerged,and the degradable filament fractured,but linked still in some case.Conclusion:The new decomposable esophageal stents are therapeutic in the benign esophageal stricture models,and can decompose in rabbits.