The Troublesome Filter

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Filter placement in the inferior vena cava (IVC) for the prevention of pulmonary embolism (PE) from lower limb and/or pelvic deep venous thrombosis is an established and safe treatment option (1Joels C.S. Sing R.F. Heniford B.T. Complications of inferior vena cava filters.Am Surg. 2003; 69: 654-659PubMed Google Scholar). Complications, including filter migration or IVC wall penetration by filter arms, are infrequent occurrences. Herein, we present an unusual case in which a Recovery filter (Bard, Mississauga, Canada) successfully placed in the IVC was complicated by apparent IVC wall perforation and subsequent migration. There have been few case reports involving the migration of this particular filter or of a broken wire migrating to the heart (2Saeed I. Garcia M. McNicholas K. Right ventricular migration of a recovery IVC filter’s fractured wire with subsequent pericardial tamponade.Cardiovasc Intervent Radiol. 2006; 29: 685-686Crossref PubMed Scopus (40) Google Scholar). A 54-year-old man presented to the emergency department with signs and symptoms suggestive of acute PE. The patient was admitted to the hospital and started on a regimen of low-molecular-weight heparin. Computed tomographic (CT) pulmonary angiography helped confirm the presence of multiple segmental PE, consistent with acute PE. No thrombus was demonstrated at lower-extremity Doppler ultrasonography (US). Despite adequate anticoagulation, the patient’s condition deteriorated and repeat CT pulmonary angiography showed evidence of further PE. A decision was made to proceed to IVC filter placement. After obtaining informed consent, access to the IVC was obtained via the right common femoral vein with US guidance. An inferior vena cavogram was obtained to evaluate the relative positions of the renal veins and iliac vein confluence and to assess the size of the IVC (approximately 1.9 cm). An incidental true retroaortic left renal vein was noted (no preaortic left renal vein component). A Recovery filter was placed within the IVC between the left and right renal veins due to the low insertion point of the retroaortic left renal vein (Fig 1). The patient’s condition improved and he was discharged home. The patient subsequently developed acute, severe right flank pain approximately 2 weeks after IVC filter placement. Abdominal CT showed a large right psoas and paraaortic hematoma. In addition, the metal arms of the filter appeared to have perforated through the wall of the IVC (Fig 2) at the level of hematoma formation. There had been no migration of the filter. The administration of Coumadin (Bristol-Myers Squibb Co, Princeton, NJ) was stopped as the international normalized ratio measured 4.0. Repeat abdominal CT performed 4 days later showed a resolving hematoma and no change in the appearance and/or position of the IVC filter. The patient’s condition deteriorated markedly 4 days later, and a repeat CT pulmonary angiogram showed extensive pulmonary thrombus. Unfortunately, it was not appreciated at the time that the IVC filter was seen protruding into the inferior right atrium on the most caudal sections. This was later appreciated (Fig 3), and the filter was removed uneventfully with placement of a Günther-Tulip filter (Cook, Stouffville, Canada) at the original lower IVC position. The patient remains well without any further complications.Figure 3Coronal maximum intensity projection CT scan shows filter migration.View Large Image Figure ViewerDownload Hi-res image Download (PPT) It is interesting that, despite the appearances of caval penetration at CT, the filter was still able to migrate into the inferior right atrium and/or IVC junction. Proctor et al (3Proctor M.C. Greenfield L.J. Cho K.J. Moursi M.M. James E.A. Assessment of apparent vena caval penetration by the Greenfield filter.J Endovasc Surg. 1998; 5: 251-258Crossref PubMed Scopus (30) Google Scholar) found in animal models that despite convincing CT evidence of IVC wall perforation at 1-year follow-up, these findings were not confirmed at necropsy. Although it is uncertain whether the filter barb penetration resulted in the psoas hematoma, it is entirely feasible given the close proximity of hemorrhage to barb position. Woodward et al (4Woodward E.B. Farber A. Wagner W.H. et al.Delayed retroperitoneal hemorrhage after inferior vena cava (IVC) filter insertion: case report and review of caval perforations by IVC filters.Ann Vasc Surg. 2002; 16: 193-196Abstract Full Text PDF PubMed Scopus (62) Google Scholar) reported an unusual case in which a penetrating barb lacerated a lumbar artery, resulting in substantial hemorrhage. If we hypothesize that the filter did play a role in the retroperitoneal hemorrhage due to IVC wall penetration by a barb and/or arm, the fact that it was later able to migrate is even more puzzling.