Resorbable inferior vena cava filters: trial in an in-vivo porcine model.

PURPOSE

To determine the feasibility, effects, and complications of a resorbable inferior vena cava (IVC) filter in a porcine model.

MATERIALS AND METHODS

Ten handmade, dual-filtration level, resorbable IVC filters were produced and gas sterilized. A dual-filtration cone was constructed using polyglycolic acid polymer strands oriented in a staggered cone formation with the apex of the cone in a cephalad orientation in relation to the IVC. IVC fixation was accomplished using a nitinol Z-stent, which was not resorbable. Operative insertion employing a paramedian incision, infrarenal vena caval dissection, venotomy, and device insertion using an 8-F rigid sheath was performed on 10 Yorkshire-type pigs (> 50 lb). Percutaneous delivery was not performed because of cost constraints. The IVC filters were operatively removed en bloc 6 weeks after implantation, and the pigs were euthanized. The IVC specimens were subsequently analyzed grossly and using light microscopy.

RESULTS

In 9 (90%) of the 10 retrieved devices, the filtration cones were completely dissolved. One device (10%) had a retained strand of filtration cone material completely incorporated into the caval wall, excluded from luminal flow. Significant inflammatory response was appreciated from the specimen histology, and significant collagen deposition was observed, especially on trichrome staining. The intima and media of 9 of 10 specimens were two to three times normal thickness. Significant reactive change was also appreciated in the pericaval lymph nodes that were taken in the specimen. One pig (10%) developed a postoperative wound infection requiring treatment.

CONCLUSIONS

Resorbable IVC filters are feasible and could be used for specific patient populations. This study outlines the need for further research of bioabsorbable polymers, absorption mechanics in the vascular system, absorption times, efficacy models, and practical application.