Empirical Study Of A New Integrated Style Stent-graft For Treating Stanford B Aortic Dissection In Canine

Objective:To design and manufacture a new device combined proximal stent-grafting with distal bare stenting for treating Stanford B aortic dissection.To research the feasibility and effectiveness of the new device in canine model of aortic dissection.With the data and experience gained from animal experiments,to develop a new integrated stent-graft device for treating human Stanford type B aortic dissection in the future.Methods:1.Integrated stent-graft device designment and Manufacture:the device was made of medical memory nickel titanium wire by heat as the skeleton support,with polyethylene terephthalate(PET)as a stent coating,using the PET stitches connect the skeleton and coating,using nickel titanium wire to make bare stents and connect with the stent-graft body.2.Canine model of aortic dissection creation:An incision was made by a left thoracotomy at the the third and fourth intercostal space to expose the descending aorta.The descending aorta was totally cross-clamped at both ends of the area suspended to surgery.Then the descending aorta wsa incised transversely along half of the aortic circumference.The distal margin aortic wall was dvided into inner and outer layer.The entry tear was mobilized approximately 5cm distally to make the dissection.After suturing the middle of the inner layer to opposite aortic wall,suture all layers of proximal and the outer layer distal to the incision together to keep blood flow into the false lumen.Finally,remove aortic clamps and increase the blood pressure to 160mmHg for 10 minutes.3.Stent-graft placement in vivo experiment:New integrated stent-graft device was transported through abdominal aorta exposed by open operation in 12 canine models of aortic dissection.The stent-graft released in the descending aorta,with covered stent covering the proximal entry tear and bare stent covering the branches of abdominal aorta.Endoleak,morphology,migration,branch vessel patency,stent endothelialization,aortic injury and inflammation were observed after the procedure.Results:1.Creation of aortic dissection model in canine:a total of 6 dogs underwent surgery,4 dogs successfully developed aortic dissection.The technical success rate was 66.7%.The dissection developed to abdominal aortic branch area in 2 dogs.2.Results of TEVAR:The success rate of integrated stent-graft device placement was 100%.The morphology,position and radiography were satisfied.All abdominal aortic branches kept patency at 3 months followed by DSA.3.Histological examination of aorta specimens:Aortic remodeling was observed Canine model of aortic dissection after TEVAR.At the covered stent and bare stent segment,the stent was patent,with the vascular endothelialization of the stent inner surface;the media of the aorta had no tear;visible new small vessels can be seen while there was no inflammation in neointimal.At the proximal and distal segment of the stent,there was no hyperplasia of the three layers of aorta,and there was no internal elastic plate and external elastic plate injury.Conclusions:The design of new integrated stent-graft device is reasonable,its easy and feasible to operate.The stent-graft showed good biocompatibility,safety and effectiveness in the canine model.This animal experiment provided valuable experience for the next clinical trials.