Prediction Model Of Postoperative Thrombosis And Vascular Remodeling Based On Blood Flow Simulation

BackgroundSignificant clinical heterogeneities were often observed among difficult and severe aortic cases.Unconventional and complicated surgery strategies were frequently needed depending on the individual case.Framework for systemic and individualized diagnosis and treatment for complex aortic diseases is of great importance and yet to be established.Intraluminal thrombosis and the dynamic regulation of vessel diameter and wall thickness are closely related to blood flow conditions within aorta.A myriad of morphological remodeling of aorta is expected after aortic surgery due to alterations in patterns of blood flow.Panoramic models for evaluation and prediction of postoperative aortic remodeling is still in its infant,pending further investigation and elaboration.Objective1.To perform longitudinal follow-up and sequential aortic blood flow simulations after complicated aortic surgery,and to explore the relationship between postoperative remodeling and evolution of blood flow patterns;2.To evaluate and predict the dynamic process of intraluminal thrombosis during follow-ups using modified low-shear related thrombosis model;3.To construct an integrated framework for simulations of thrombosis and intimal hyperplasia,and to perform panoramic simulation of the mid-to-long-term postoperative aortic remodeling process based on data collected from short-term follow-up.Methods1.Radiological follow-ups were performed in a patient with middle aortic syndrome complicated with aortic rupture and right renal aneurysm,at 1,3,and 6 months after receiving hybrid aortic surgery of extra-anatomic bypass and endovascular reconstruction of aorta and bilateral renal arteries.Blood flow simulations were carried out and compared with patterns of aortic remodeling.Reliability of modified low-shear related thrombosis model in predicting the dynamic thrombosis formation was validated.2.According to the correlation between postoperative aortic remodeling and characteristics of the blood flow,integrated framework for simulations of thrombosis and intimal hyperplasia was constructed based on the diffusion-convection-response equation of fluid substance transport.Simulation was performed to reproduce the course of postoperative aortic remodeling.Results1.Stenosis of the aorta progressed during follow-up.Aortic segments without stent coverage between the proximal and distal anastomotic sites of aortic bypass showed narrowing of the diameter and relative thickening of the wall.Irregular small filling defects appear in the distal and proximal segment of aortic stent at 6 to 8 months postoperative,suggesting focal thrombus formation.2.Flow competitions between aortic stenotic site and the aortic bypass were observed in the abdominal aorta shortly after surgery.With the progression of aortic stenosis,reversed and stabilized abdominal blood flow was gradually established.Increased reverse perfusion and reduction in diameter synergistically restored wall shear stress of the abdominal aorta to a physiological level.Model of thrombus formation can effectively predict the dynamic evolution of intraprosthetic thrombosis.3.The integrated simulation model of thrombosis and intimal hyperplasia could accurately reproduce the progress of postoperative aortic remodeling and blood flow redistribution.Fidelity and accuracy of the simulation could be further obtained through titration of values of model parameters.ConclusionsPatterns of postoperative aortic remodeling is closely related to hemodynamic factors of the aorta.Based on the representative remodeling mechanism,an integrated simulation model could be established,which can perform panoramic simulation of the mid-to-long-term postoperative aortic remodeling process based on data collected from short-term follow-up.The predictive model of vascular remodeling can be applied to clinical individualized diagnosis and treatment,and guide the design and development of novel strategies for aortic surgery.