Design And Study Of A Novel Biodegradable Inferior Vena Cava Filter

Blood coagulates abnormally in the deep vein,which called Deep Vein Thrombosis,which is a lower extremity venous reflux disorder.The falling thrombosis of venous flow through the heart to reach the lungs with the venous blood,blocking the pulmonary artery,affecting the exchange of oxygen and carbon dioxide,causing suffocation,which is called pulmonary embolism.Pulmonary Embolism is one of the three fatal cardiovascular diseases.Placing the inferior vena cava filter is commonly used in clinical prevention of pulmonary embolism,inferior vena cava filters are almost metal filters.Metal filters can filter thrombus,achieve the purpose of prevent the pulmonary embolism,but which must face occlusive deep vein thrombosis,displacement,removal of the second surgery and so on.It is based on this,the topic studies and designs a new type of complete biodegradable inferior vena cava filter.In the premise of thromboprophylaxis thrombosis,it can meet the premise of biological complete degradation,will not affect the blood flow without the removal of the second surgery.After referring to a large number of domestic and foreign literatures,and discussing,analyzing and summarizing,we design two new types of biodegradable IVC filters,and draws them separately with professional drawing software Solidworks.After processing the mold,we use 0.5mm high molecular polylactic acid fiber to hand knit the filter body respectively and the supporting structure,and 0.15 mm polylactic acid silk was used as the filter part of the filter.After weaving the finished samples,the samples were subjected to analyze structural,finite element and degradation experiments.During the degradation experiments,the change of the investigate topography,the change thermodynamic,the change of the molecular weight,the change of the viscosity and radial support strength are followed up.At the same time,the crimp expansion test under the conditions of 37 ? and the capture experiments in vitro thrombus are performed.After analyzing the structure of different filters,the final design of the filter is a one-piece filter with double-layer.The supporting structure was crimped to 5.5mm,6.0mm,7.0mm,comparative analysis of finite element data.It was concluded that the maximum radial support strength of the support structure did not exceed the maximum strength of the polylactic acid filaments when crimped to 5.5 mm,6.0 mm,7.0 mm,When crimped to 5.5 mm and 6.0 mm,the support structure circle has begun to contact.During the press-grip process,the squeezing action between the circles causes the support structure to vary greatly in radial support force during expansion and rebound.The maximum rate of expansion of the support structure was achieved at 7.0 mm.In vitro degradation process,with the degradation time increases,the sample surface morphology damage,molecular weight decreases,the radial strength of support decreased.The sample hold-back springback experiment at 37 ° C showed that the shorter the hold-up time,the longer the release time,the better the support structure's recovery.In vitro thrombus capture experiments,the double-layer filter structure of the average thrombus filtration rate of 85%,single-layer filter structure thrombosis average rate of 65%,so a comprehensive comparison,the selection of double-layer filter structure can be more effective to capture thrombus,so the design of the filter structure is an integrated double filter.