Animal Experiment Research Of Self-made Left Atrial Appendage Occluders Implanted By Tercutaneous And By Thoracotomy

Background:Atrial fibrillation is one of common arrhythmia in clinic.The follow-up research of patients with atrial fibrillation shows that the incidence of stroke is up to nearly20%in five years.The reason of stroke resulting of atrial fibrillation is thrombosis in left atrial appendage (LAA) and thrombus off. The main reason of thrombosis and embolism is LAA’s special anatomical structure.LAA is the remnant of primitive germ of left atrium formation in the third week of pregnancy, with rich toilet muscle and trabecular, and uneven. When atrial fibrillation happens hemodynamics abnormality and atrial unrhythmic contraction lead to that blood flow velocity of diastolic left atrial slow down obviously, and blood stasis brings about thrombosis in the end. At present, the most effective therapy of the prevention and control of thromboembolic events are anticoagulation. The clinic use of anticoagulant drugs is severely limited because of constant monitoring of blood coagulation function and bleeding complications. Especially the elderly and the patients with hemorrhagic disease can not receive therapy of anticoagulation, then how to prevent stroke? It is a clinical problem. In theory to remove LAA can reduce the incidence of thrombosis rooting in AF. At present the method of removing LAA include surgery and the transcatheter implantation of occluder. The surgical method is difficult to ensure the ligation surface smooth, without sag and folds, otherwise surgical method can not reach the purpose of treatment. While transcatheter implantation method requires anatomy of opening of LAA strictly.The smaller openings of LAA are easy to be implanted, but the bigger openings of LAA are hard to be implanted, and the success of occluding LAA is associated with the occluder’s shape and structure. The nickel titanium alloy LAA occlusion devices for basic and clinical applications have made progress in domestic and foreign, and demonstrated that occludering LAA is an effective therapeutic method of thrombus prevention of atrial fibrillation.But the applications of occlusion device and technology of occlusion are in the study.Objective:To observe the feasibility, efficacy, and safety of the transcatheter or thoracotomy implantation of a self-made left atrial appendage occlude in animal models, and to give some experimental evidence for the clinical research and application.Methods:We selected22healthy and majority dogs which were divided into the experimental group A(A group) and experimental group B (B group)randomly. A group with12dogs established dog model by percutaneous fossa ovalis of atrial septal puncture to implant with self-made left atrial appendage occlude. B group with10dogs establish dog model by thoracotomy to implant with self-made left atrial appendage occlude. Implantation of occluder is guided by DSA and TTE. Dogs were sacrificed in1week and1,3,6month respectively after device implantation,while tissue samples were obtained for gross examination, histological examination, and SEM examination, to evaluate the endothelialization after implanted the new type occlude,to observe complications such as residual shunt and superficial thrombus formation.Results:A group, success rate of implantation by transcatheter was82%。One died of acute cardiac tamponade because of percutaneous fossa ovalis of atrial septal puncture.One was not implanted the occlude because LAA didn’t conform to the size of occlude.One died in24hour postoperation, because the occlude fell off. B group, success rate of implantation by thoracotomy was89%. One died of bleeding in operation.One died of VF because of air embolism after implantation.(2)17dogs were sacrificed in1week and1,3month respectively after device implantation,and the tissue samples showed that two groups were not dislocation.The nitinol wires were not fractured.There was no superficial thrombus formation or ecptoma.In two groups, the surface of LA-disk of the occluder was not covered with tissue in1week,and covered mainly with smooth lamellar lucency tissue in1month.Histological and SEM examinations revealed that the surface was fibrous tissue and endothelial cells. The edge of the occluder confluenced partly with the surrounding of the endocardium of the atrial wall. In two groups, the flat surface covering on the LA-disk of the occluder was thickened, and the edge of the occluder confluenced completely with the surrounding of the endocardium of the atrial wall in3month.Conclusion:The way of implantation of a self-made left atrial appendage occluder by transcatheter or by thoracotomy in animal models is feasible, safe, and effient. If the anatomical feature of LAA is not suitable for implantation by transcatheter, we can choose the way by thoracotomy implantation.