FOLLOW-UP AFTER INSERTION OF BIRDS-NEST INFERIOR VENA-CAVAL FILTERS

OBJECTIVE: To determine the long-term clinical and radiographic outcom e of patients who undergo insertion of a Gianturco-Roehm Bird's Nest v ena caval filter (Cook Inc., Bloomington, Ind.). PATIENTS AND METHOD: The medical records of 40 patients who, over a 34-month period, underw ent insertion of a Bird's Nest filter were reviewed and the reasons fo r filter insertion determined. The causes of any subsequent deaths wer e noted, and the autopsy findings, when available, were reviewed. Surv iving patients were contacted, and 12 were wiping to return for follow -up imaging, which consisted of plain radiography, real-time ultrasono graphy, colour Doppler imaging and contrast-enhanced computed tomograp hy. Changes in filter position, the presence of thrombus and perforati on of the vessel wall by the biter struts were documented. RESULTS: Al l 10 patients who underwent filter insertion while in an intensive car e unit (ICU) died, an average of 22 days after the procedure. Eleven o ther patients also died. Recurrent pulmonary embolism was not suspecte d in any of these patients, and five autopsies revealed no caval throm bosis. Imaging studies in 12 of the surviving patients revealed no occ lusion of the inferior vena cava and no filter migration; however, the vena caval wall was perforated in all of these patients. Nonocclusive intrafilter thrombus was detected by colour Doppler imaging in three patients. CONCLUSIONS: In this small group of patients the Bird's Nest filter was effective in preventing recurrent pulmonary embolism and c aused less caval thrombosis than has previously been suspected, althou gh intrafilter clot was found in 25% of the patients who underwent fol low-up imaging. Colour Doppler imaging is the method of choice for det ecting nonocclusive thrombus with this type of filter. Perforation of the caval wall was universal but not clinically symptomatic. Finally, guidelines should be established to ensure the cost-effective use of i nferior vena caval filters in ICU patients.