[Vena cava umbrella filter: complications and treatment]

Increasing numbers of vena canal filters are being implanted to prevent pulmonary embolism, which are mainly the consequence of deep vein and pelvic vein thrombosis. Can a filter be removed again in case of complications arising from it? What is the risk of such operative explantation? What is the subsequent risk of pulmonary embolism?

In nine patients (5 males, 4 females; mean age 45 (30-39 years) who had vena caval filters implanted because of thromboembolism despite anticoagulation, complications due to the filter required its operative removal and thrombectomy of the large veins 3 days to 48 months after implantation in the inferior vena cava (IVC). One inguinal arteriovenous fistula (due to perforation of rods of a displaced filter) were closed. The patients' case note were retrospectively analysed and eight of the nine patients' were reexamined according to a standardized procedure a mean of 20 months after removal of the filter.

Explantation of the filter had been successful in all patients. But there were two nonfatal postoperative complications: a pulmonary embolus and a paradoxical cerebral embolus. In one patient a segmental stenosis of the IVC with retroperitoneal collateral circulation was found at operation. All but one of 16 pelvic veins that had thrombectomies performed at the time of filter explanation were patent, as were the IVCs in seven of the eight re-examined patients. None of the patients had evidence of postoperative pulmonary embolism.

Vena caval filters can be explanted with a low operative risk. After removal and venous thrombectomy, implantation of another caval filter is unnecessary. As anticoagulation properly monitored is almost always an effective measure in the prevention of pulmonary thromboembolism, filter implantation should be performed only on the strictest indication, as an ultimate step.