A Newly Designed Retrievable IVC Filter: Experimental Study

【Purpose】:To evaluate the efficacy ,feasibility and safety of a newly designed retrievable inferior vena cava filter in vitro and vivo experiment.【Method】:In vitro, thrombus capture rate and stability of the new IVC filter and the Recovery retrievable filter were tested in varied thrombus diameters, tube diameters and positions, and the experiment was repeated by using a piece of cow aorta in stead of the silica gel tube. In vivo,7 swine were used for acute study for testing the deployment and retrievability, also including the emboli trapping ability in vivo for preventing pulmonary embolism. Another 19 were used for long term study, the animals were divided into two groups, group A and B,A=5,B=14. stability, thrombus formation tendency, retrievability and the gross and histological IVC changes at different time intervals(10-60day) were studied.【Result】:In the vitro flow model, the emboli capture rate of different embolism diameter were 91.5%,96.5%,99.5%;different tube diameter were 98%,93.67%; and the two directions were 94.33%,97.33%, the total capture rate was 95.83%, the capability of the new filter was better than Recovery filter(91.5%,81%)(P<0.05).when using cow aorta, the capture rate, respectively, were 88.5%, 94%,98%; 94.67%,92.33%; 91.33%,95.67%, and total rate was 93.5%, in larger diameter aorta, there was no significant difference with the corresponding silica gel tube(P>0.05). In vivo study, 19 deployment and 15 retrievement were finished smoothly in acute study,for 1,the position of filter was a little higher, one leg of the filter entered the left renal vein, and the filter was deflected obviously, other filters were normal during manipulating. All the filter during 60D were successfully retrieved and no vena cava injury and retroperitoneal abnormality were found, the endomembrane turned thickened mildly after 10-day dwelling; the filter legs were covered by the intima after 20-day dwelling, and the membrane was obviously thickened after 40-60 day dwelling.【Conclusion】:The newly designed IVC filter was safe and effectively prevent the happening of PE, it can be reliably and safely retrieved acutely and as long as 60 day after implantation in swine.