Thrombosis of Vena Cava Filters: an Analysis of Explanted Filters

摘要

Thrombosis of the inferior vena cava (IVC) following implantation of a filter is one major drawback of this endovascular treatment. Reduction of the thrombosis rate would increase the widespread application of IVC filtration, especially in younger patients. Hypotheses concerning thrombus formation in filters include thrombogenicity of the filter material, hemodynamic alterations and entrapped clots. To sort out these possible causes, we analyzed Gtinther-Tulip (Cook) retrievable inferior vena cava filters removed from patients up to three weeks after implantation. Analyses included observation of biological tissue attached to the filters (light microscopy and histological analysis) and physico-chemical analysis of the cleaned filter's surface (SEM, AES, XPS). Light microscopy examination showed two main types of thrombi. Light beige fibrous thrombi are mainly found in the apex of the filter and at the junction of the struts and the petal -shaped branches (thereafter called "junctions"). Dark less brittle ones are mostly present at junctions. Preliminary results didn't show histological differences between thrombus from different types and filters. Initial SEM observations showed irregularities on surface of non-implanted filters and various degrees of corrosion on implanted ones. AES showed an oxide layer thickness of typically 10 nm for non-implanted filters.