December 12, 2008

Absorbable Inferior Vena Cava filters (VCF): An In-Vivo Porcine model

Axel Thors, DO, Patrick Muck, MD.
Good Samaritan Hospital, Cincinnati, OH, USA.

OBJECTIVES: The use of vena caval filters (VCF) in the acute care surgical patient continues to expand. This increased use has lead to further product development pertaining to the type of device that is inserted. This study is the first of a multi-part series to determine the efficacy and feasibility of an absorbable VCF in an in-vivo porcine model.
METHODS: A total of 10 hand-made, dual filtration level, absorbable VCF’s were produced and gas sterilized. Operative insertions using paramedian incisions, infra-renal vena cava dissection, venotomy, and device insertion using 8F rigid sheath was performed on 10 pigs (>50lbs). Six-weeks after implantation, the VCF’s were operatively removed en-bloc and the pigs euthanized. The filters were grossly inspected for measure of absorption, retained residual material, migration, and clot burden. Subsequently the inferior vena cava (IVC) specimens were examined under microscopy to assess for degree of inflammatory response to the present foreign body.
RESULTS: All devices were completely dissolved (100%), with no signs of migration, residual material, or clot burden. The non-absorbable Z-stent portion of the design was completely incorporated into the vena cava wall with complete neointimalization of the vena cava lumen. There was no evidence for residual knots or strands in the caval wall, nor was there evidence of IVC narrowing. One pig (10%) developed a post-operative wound infection requiring treatment. Filter and vena cava specimens were preserved in formaldehyde and sent for histology.
CONCLUSIONS: To date there are no commercially available absorbable VCF devices, nor has this concept been published in the medical literature. The application of such a device could fit a specific subset of patients.

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