Cause analysis and removal strategy of difficult retrieve filters

Objective To study the causes of difficult retrievable inferior vena cava filter and its removal strategies. Methods A retrospective analysis was made of 405 DVT patients admitted to Taizhou Hospital of Zhejiang Province from January 2017 to October 2018. Among them, 232 cases underwent filter implantation in the simple filter implantation group, 173 cases were treated in the endovascular treatment group. One hundred and one cases in the filter implantation group and 160 cases in the endovascular treatment group underwent filter removal treatment. There were 30 cases with inferior vena cava filter implantation could not be successfully removed by conventional trap technique in these two groups. Ten cases with tilted filter or adherent filter, and 2 cases with thrombus captured were found in the simple filter implantation group. In the endovascular treatment group, 17 cases were found filter tilted or displaced and 1 case was found with thrombus captured in the filter. For patients captured thrombus in filter, catheter thrombolysis assisted with conventional trap technique and catheter suction assisted with conventional trap technique were used to remove filers. For the patients with tilted filter or adherent filter, catheter assisted with conventional trap technique and Ring-assisted stiff wire pulling hook end method were used to retrieve filters. Results One case was removed by catheter thrombolysis assisted with conventional trap technique, 2 cases by catheter suction assisted with conventional trap technique, 24 cases by catheter assisted with conventional trap technique, and 2 cases by Ring-assisted stiff wire pulling hook end method, 1 case with filter adhered severely to the vena cava could not remove the filter. Successfully retrieved 29 filters, the technical success rate was 96.7%. Conclusion Inclination, adherence and thrombus capture are the main causes for the difficulty of removal of inferior vena cava filters. The recovery rate can be improved by using various assistant trapping techniques.