Numerical Analysis Of Graft Stent For Stanford B-type Aortic Dissection Of Thoracic Endovascular Aortic Repair

In recent years,with the rapid development of economy and the great improvement of people's living standards,cardiovascular and cerebrovascular diseases have become a common disease,and thoracic aortic dissection has become a major problem endangering human health.Thoracic Endovascular Aortic Repair(TEVAR),as a new therapeutic approach for Thoracic Aortic aneurysm and Thoracic Aortic dissection,was developed in 1999 by applying graft stents.The rupture of the vessel is prevented by implantation of a graft stent in the lumen.For more than a decade,thoracic aortic endovascular therapy has been minimally invasive,and more importantly,the introduction of membrane materials is more conducive to the formation of a sealed cavity at the site of hemangioma.It avoids further impact of blood flow on the weak vessel wall and has become the preferred treatment for thoracic aortic disease.As the main instrument for treatment of thoracic and abdominal aortic lumen,most of the graft stents have the property of self-expansion.After release,they deformed in response to the curvature of the aorta,resulting in a resultant force interaction between the thoracic aorta and the stent.Further study of its interaction is of great value in understanding the mechanism of major postoperative complications in thoracic aortic endovascular therapy,formulating corresponding prevention and treatment methods,and guiding graft stents design.Numerical simulation has the advantages of high accuracy,fast operation and convenient parameter adjustment,etc.In recent years,it has been gradually applied to the study of digital model of thoracic aorta,vascular hemodynamics,and the interaction between graft stents and peripheral arteries.However,there are few reports on the numerical simulation of the graft stent used in thoracic aortic cavity repair.The brief steps of numerical simulation analysis on the service process of intracavity repair with graft stent are as follows :(1)The geometric model of thoracic aorta combined with stent was established by using the CT or MRI images of patients after intracavitary repair;(2)Modeling was performed according to the real graft stent structure implanted in vivo,and then a straight stent and a curved stent were established.(3)The compression implantation process of two kinds of graft stents was simulated numerically,and the stress of each structure during the compression implantation process was analyzed.(4)The results of fatigue strength analysis were carried out to verify the safety of the implantable bent graft stent after applying pulsating load." The background and parameters of the simulation are as close as possible to the real situation inside the human body " is the key to obtain accurate results.The geometric model is based on the patient's own image.In this study,two types of graft stents suitable for the treatment of Standford B type aortic dissection were studied and analyzed by using the finite element analysis method.Finite element models of two kinds of graft stents were established and simulated by Abaqus software.In the whole process,the study of the force of the graft and the analysis of the bending graft stent under the action of pulsating load is the focus of simulation.Through the analysis of the simulation results,the law of force influence of two kinds of graft stents in the application of intracavity repair was obtained.It is crucial to understand the characteristics of each structure of the graft stent,reasonably select different stents for different lesion sites,successfully perform Stanford B type aortic dissection intracavity repair,and reduce postoperative complications.