Three Dimensional Modeling And Finite Element Analysis Of Bioprosthetic Heart Valves Based On CT Images

With a rapid aging population the incidence of cardiovascular disease had also increased. Among these disease, valvular heart pathological change is very common in China, which might seriously threaten the life of every patient as well as his/her whole family welfare. Causes of such dysfunctions are mainly considered to be degradation of structure, fatigue failure and valve calcification. Patients in severe condition need timely replacement of heart valves. Bioprosthetic heart valves (BHVs)share similar hemodynamic performance with native valves, both of them have little effects on blood. Compared with other measures, this approach cause less complications even without anticoagulation. But there are several limitations with BHVs, the worst is its durability, under, constant blood flowing accompanied with tissue degradation, calcification and leaflets tear. It is of great significance to find out the failure mechanism of BHVs. Effort to design substitute with great fatigue property are need.In this paper we extracted data from continuous 2D computed tomography (CT)images of heart. A series of preprocess were did with those images including threshold extraction, edit, modify, regional growth and secondary grid generation, arriving at 3D reconstruction of heart valves and aortic vascular. Further optimization was done to get a model precisely described the structure of native heart valves. This is a good resource for finite element analysis after cloud points disposing, polygon process and surface analysis. Information about stress and strain from simulation is a strong supplement of vitro tests.In finite element analysis software package ANSYS Workbench, we did dynamic analysis of BHVs by applying constant pressure to leaflets. Settings such as material properties of blood, leaflets and vessels were all from clinic dada. We could found that leaflets tear are related to maximum stress and the degree of stress focus. The most likely parts to be tore apart are sections showed Max-stress. Actually they were suturing positions of separate leaflet. Generally, the thickness of a single leaflet ranges from 0.25 to 0.5 mm. We define it as a variable, simulations with distinct values showed that the BHVs performed best when its thickness is 0.4 mm, which might be a reference for the choice of thickness to BHVs designers. With 3D models of heart valves and aortic vascular based on CT data, we could gain the maximum equivalent stress, the maximum principal stress and the maximum shear stress change with the thickness of the BHV more obvious. This is a rewarding explore that provides useful reference for optimal design of BHVs design.