Computer Aided Optimization Of Thoracic Endovascular Aortic Repair

Cardiovascular diseases have been the number one killer of human health.The number of deaths from cardiovascular diseases ranks first in China and has exceeded 40% of the total deaths from diseases,which is higher than that of tumors and other diseases.The prevention and treatment of cardiovascular diseases have become the focus of research.The heart is the "power pump" of the human blood circulation,while the aorta is like the "main conduit" of the cardiovascular system.The aorta directly connected to the heart is responsible for the important function of distributing blood.Hemodynamics is conducive to evaluate the health of the aorta and predict disease risk.Common aortic diseases include aortic dissection,aortic aneurysm and so on.The conventional clinical treatment method is thoracic endovascular aortic repair(TEVAR).However,it is impossible for current clinical measurement technology to accurately obtain comprehensive hemodynamics and effectively assist clinicians in the decision-making process.A human aortic blood flow model was established in the present study.Based on the computational fluid dynamics method,the blood is simplified to a single-phase non-Newtonian fluid and the Windkessel model is coupled to obtain physiological pressure waveforms.Two-way coupling method is used to capture the interaction of blood flow with the aortic wall.Our model was used to quantitatively study the effect of complex TEVAR on aortic hemodynamics.The contents of this thesis can be divided into three parts.In the first part,the efficacy of TEVAR with left subclavian artery(LSA)coverage was explored.To obtain an adequate landing area,the LSA was blocked by the endograft.Threedimensional geometric aortic models were reconstructed based on clinical medical images.Blood flow simulations were carried out before and after TEVAR.The effects of LSA coverage on aortic hemodynamics were analyzed.Besides,a postoperative aortic model with LSA was virtually constructed and the hemodynamic significance of LSA was accessed.It is recommended to reconstruct the blocked LSA clinically from the perspective of hemodynamics.We performed the investigation of TEVAR with a single in situ fenestration(ISF)in the second part.When the LSA is blocked by the endograft,the target vessel can be reconstructed using in situ fenestration technology.Firstly,a real clinical patient was selected and postoperative hemodynamics was obtained,where the abnormal distribution of blood flow and pressure were observed.Subsequently,two postoperative aortic models were virtually constructed and we demonstrated the impact of the protruding length of the LSA stent on hemodynamics,while the risk of postoperative complications was also compared.Finally,based on an ideal aortic geometric model,the effects of protruding length and angle on postoperative hemodynamics were comprehensively analyzed,and the results were consistent with that of patient-specific cases.The shortcomings and long-term risks of ISF-TEVAR were discovered,providing a theoretical basis for clinicians to improve the surgical plan.In the last part,the efficacy of TEVAR surgery with in situ double-fenestration was revealed.We reconstructed two representative postoperative aortic models.The blood flow model established in this thesis was applied to obtain hemodynamic parameters.The simulation results provide evidence for the harmful effects of the typical double-fenestration morphology on the blood flow field of the aortic arch.