Evaluation of the retrievability of the OptEase IVC filter in an animal model

PURPOSE: A new inferior vena cava filter was evaluated in vivo to determine the percutaneous retrievability after an implantation period of up to 18 days. MATERIALS AND METHODS: The inferior venae cavae of six goats were percutaneously implanted with three filters, and one animal received two filters. To assess filter stability, a plain radiograph was obtained after 7-9 days and on the day of retrieval. After cavography, filter retrieval with an endovascular snare and retrieval catheter was performed in three animals after 12 days and in three others after 14 days. In one animal, retrieval of one filter was performed after 18 days, and one filter was intended to be permanent. Twenty-eight days after filter retrieval, cavography was performed before inferior vena cava removal for gross and histologic examination. RESULTS: All filters (N = 20) were implanted without complications. There was no migration during the implantation period. Preretrieval cavography demonstrated all filters to be patent and centered. Filters intended for retrieval (n = 19) were all successfully extracted at 12 (nine filters), 14 (nine filters), and 18 days (one filter). For the animal with the filter extracted at 18 days, one filter remained in situ intentionally. Postretrieval cavography showed no visible signs of vessel wall anomalies. There were no complications during the 28 days of follow-up after retrieval. Presacrifice cavography showed no evidence of caval wall abnormalities. In all animals, gross examination of the inner wall of the explanted vena cava showed only minimal macroscopic changes. The struts of the filter in situ for 46 days (18 days with 28 days of follow-up) were overgrown with neointima. Histological study of the 19 filter retrieval sites revealed no to moderate intima proliferation, minimal residual signs of hemorrhages, and no or only occasional slight inflammatory reaction. CONCLUSIONS: In this animal model, the new vena cava filter demonstrated event-free retrieval, without postretrieval complications, up to 18 days postimplantation. After implantation of 46 days, the filter showed neointima overgrowth of the struts