ABSTRACT
Objective To investigate filtration efficiency of convertible vena cava filters on treating pulmonary embolism under the condition of different thrombus diameter and content. Methods Three kinds of convertible vena cava filter models with different filtering unit structures (L-style, S-style, W-style) were constructed to numerically simulate hemodynamics based on computational fluid dynamic (CFD) methods, and their filtration efficiency were comparatively analyzed under the condition of different thrombus diameter (5, 10, 15 mm) and content (10%, 15%, 20%). Results With the increasing of thrombus diameter and content, the volume fraction of thrombus distributed on the filter bars increased and filtration efficiency of the filter became better. When the thrombus diameter was 5 mm, the S-style filter’s filtration efficiency was the best as compared with the other two styles of filters. When the thrombus diameter was 10 mm, the W-style filter showed the best filtration efficiency. When the thrombus diameter was 15 mm, the S-style and W-style filter showed the same filtration efficiency, which was better than the L-style filter. Conclusions The implantation of vena cava filters will cause hemodynamic changes, and its filtration efficiency is not only related to filtering unit structures, but also closely related to the diameter and content of thrombus. These results provide a theoretical reference basis for the design and clinical choice of the novel convertible vena cava filter.
ABSTRACT
Objective To investigate filtration efficiency of convertible vena cava filters on treating pulmonary embolism under the condition of different thrombus diameters and contents.Methods Three kinds of convertible vena cava filter models with different filtering unit structures (L-style,S-style,W-style) were constructed to numerically simulate hemodynamics based on computational fluid dynamic (CFD) methods,and their filtration efficiency was comparatively analyzed under the condition of different thrombus diameters (5,10,15 mm) and contents (10％,15％,20％).Results With the increasing of thrombus diameter and content,the volume fraction of thrombus distributed on the filter bars increased and the filtration efficiency of the filter became better.When the thrombus diameter was 5 mm,the S-style filter's filtration efficiency was the best as compared with the other two kinds of filters.When the thrombus diameter was 10 mm,the W-style filter showed the best filtration efficiency.When the thrombus diameter was 15 mm,the S-style and W-style filter showed the same filtration efficiency,which was better than the L-style filter.Conclusions The implantation of vena cava filters will cause hemodynamic changes,and its filtration efficiency is not only related to filtering unit structures,but also closely related to the diameter and content of thrombus.These results provide a theoretical reference basis for the design and clinical choice of the novel convertible vena cava filter.
ABSTRACT
Objective To investigate filtration efficiency of convertible vena cava filters on treating pulmonary embolism under the condition of different thrombus diameters and contents.Methods Three kinds of convertible vena cava filter models with different filtering unit structures (L-style,S-style,W-style) were constructed to numerically simulate hemodynamics based on computational fluid dynamic (CFD) methods,and their filtration efficiency was comparatively analyzed under the condition of different thrombus diameters (5,10,15 mm) and contents (10％,15％,20％).Results With the increasing of thrombus diameter and content,the volume fraction of thrombus distributed on the filter bars increased and the filtration efficiency of the filter became better.When the thrombus diameter was 5 mm,the S-style filter's filtration efficiency was the best as compared with the other two kinds of filters.When the thrombus diameter was 10 mm,the W-style filter showed the best filtration efficiency.When the thrombus diameter was 15 mm,the S-style and W-style filter showed the same filtration efficiency,which was better than the L-style filter.Conclusions The implantation of vena cava filters will cause hemodynamic changes,and its filtration efficiency is not only related to filtering unit structures,but also closely related to the diameter and content of thrombus.These results provide a theoretical reference basis for the design and clinical choice of the novel convertible vena cava filter.
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Objective To analyze and compare the effects of structure parameters on synchronous motor ability between the blood vessel and stent after stent implantation by using finite element method and grey correlation theory. Methods The magnesium alloy stent of S closed-loop type was selected, and 9 models of such stents with different materials, numbers of support in circumferential direction, support lengths and initial diameters were established by using SolidWorks, and these stent models were meshed by using HyperMesh. The synchronous motor ability between the blood vessel and stent after stent implantation was simulated by using ABAQUS, and the influencing factors of different structure parameters on bending stiffness were investigated and compared by using grey correlation theory. Results The effect of materials on stent flexibility was obvious. The flexibility of magnesium alloy stent was the best, and the bending stiffness was 0.958 N•(rad•mm)-1; the best flexibility of stents were those with 5-support in circumferential direction, 1.0 mm-support length, and 1.4 mm-initial diameter, and their bending stiffness was 0.853,0.829 and 1.024 N•(rad•mm)-1, respectively. Conclusions The flexibility of magnesium alloy stent is the best, followed by stainless steel stent, and cobalt-chromium stent ranks last. With the increase of support numbers in circumferential direction, support length and initial diameter, the stent flexibility shows the decreasing tendency; the grey correlation analysis shows that the effect of materials on stent flexibility is the most significant, followed by support numbers in circumferential direction and support length, while initial diameter exerts the smallest influence. The analysis of structure parameter effects on stent flexibility will provide more scientific guidance for stent design and development as well as its intervention treatment in clinic.
ABSTRACT
Objective To investigate the interaction between vessel and vena cava filter (VCF) with different numbers of support poles and the influence on blood flow during its implantation by using finite element method and computational fluid dynamics method, so as to provide more scientific guidance for intervention treatment and design & development of the filter. Methods Three kinds of VCF models with 4, 6, 8 support poles were established by using Solidworks, respectively. The stress distribution and radial support stiffness of the vessel and filter under working condition were then simulated and analyzed by using ABAQUS. The distributions of blood flow velocity, pressure and shear stress after VCF implantation were simulated by using Fluent. Results All the mechanical and fluid properties of the three kinds of VCFs were within the scope of security. The comprehensive mechanical performance of the 6-pole filter was better, while for the 8 pole-filter, it showed larger stress under working condition, larger support intensity, higher exit velocity, larger shear stress on the filter mesh, and the trail of the flow was changed from laminar to transition flow, which might cause some damage to the vessel wall. The 4 pole-filter under working condition had a larger stress on the vessel, while its exit velocity was lower, which could be likely to cause local damage on the vessel wall, and disadvantageous to accurately positioning the filter in diseased region of the vessel. Conclusions The 6 pole-filter has a superior hemodynamic effect and comprehensive mechanical properties, which reduces the potential possibility of damage to the vessel wall caused by implantation of the filter. The simulation analysis on VCF provides a good reference for design of the filter and its intervention treatment in clinic.