An experimental study on a new type of biodegradable vena cava filter

Objective To evaluate a new biodegradable inferior vena cava(IVC) filter by in vitro and in vivo experiments. Methods The biodegradable filter consisted of metal stent and absorbable suture, which acts as a degradable deformable switch of the filter. When the suture of the proximal metal filter degrades and lost its tension, the metal filter will change into a stent. In vitro experiments were performed to test the influence of the sterilization method and the tension of absorbable sutures to the filter′s self-convertible time, animal experiments were conducted to evaluate the effectiveness of emboli capture and to observe the in vivo self-convertible time of the filter. IVC stenosis , pulmonary embolus and intimal hyperplasia and inflammation were evaluated. Results Ethylene oxide sterilization did not have an adverse effect on the self-convertible time of the filters. The tension did not affect the degradation rates of the suture significantly. In animal experiments, the VCFs were successfully implanted via femoral vein approach. Not any tilt, migration or structural damage of the filters was found during the follow-up time. Postoperative fluoroscopy and autopsy confirmed that there was no stenosis or thrombosis, IVC perforation. After implantation large thrombi were captured.The sutures degraded and filters transformed into stents in 3 weeks. After 90 days IVC was patent with mild intimal hyperplasia and no thrombosis. Conclusions This study demonstrated the effectiveness and safety of the biodegradable filter we designed. Key words: Venous thrombosis; Pulmonary embolism; Biodegradable vena cava filter; Self-convertible time