Single institution prospective evaluation of the over-the-wire Greenfield vena caval filter.

PURPOSE: To assess the technical and clinical success of the over-the-wire (OTW) Greenfield inferior vena caval (IVC) filter. MATERIALS AND METHODS: Prospective evaluation of the OTW Greenfield filter in 47 patients was performed during the course of 18 months. Technical success and deployment problems were documented. Caval perforation, leg asymmetry, and tilt were evaluated with a postprocedure, noncontrast computed tomographic (CT) scan. Follow-up was performed at 6- and 12-month intervals after the procedure and included a clinical history, chart review, and magnetic resonance (MR) imaging examination of the IVC. RESULTS: Ninety-one percent of filters were placed without technical difficulties and 100% were successfully deployed. Technical difficulties included sheath kinking prior to deployment (n = 3), initial incomplete filter opening (n = 1), and wire entrapment within the filter (n = 1). Of 38 patients evaluated with CT, there was no case of caval perforation. Twenty-one patients (55%) demonstrated tilt and 14 (37%) had leg asymmetry. Tilting occurred more frequently when the filter was placed from a femoral approach (51%) than from a jugular approach (12%). Of patients with leg asymmetry, the vena cava was narrow in anteroposterior (AP) dimension in five (36%). Of 13 deaths, none were attributed to pulmonary embolism. One patient (2%) had a recurrent pulmonary embolus. Two of 16 patients (12%) with MR imaging follow-up had documented IVC thrombosis. CONCLUSIONS: The OTW Greenfield filter has an effective delivery system, with few difficulties encountered during deployment. Filter tilt and leg asymmetry are common. The etiology of leg asymmetry is likely multifactorial but is often associated with a cava with a small AP diameter. Because OTW deployment appears to offer no benefit in centering the filter, the authors have elected to remove the wire prior to filter deployment to avoid possible entanglement. MR imaging follow-up reveals an acceptable incidence of IVC thrombosis.

Effect of anatomic distribution of pulmonary emboli on interobserver agreement in the interpretation of pulmonary angiography.

OBJECTIVE: This study examines the anatomic distribution of emboli on pulmonary angiography and attempts to determine the relationship of vessel size to interobserver agreement, two factors having important implications in comparing pulmonary angiography with cross-sectional imaging for pulmonary embolism. MATERIALS AND METHODS: One hundred twenty-five consecutive pulmonary angiograms were reviewed retrospectively by three interventional radiologists. Initial interpretations were recorded and compared to determine interobserver agreement on a per-patient and per-embolus basis. Discordant interpretations were reviewed by all radiologists for a consensus interpretation. RESULTS: Unanimous per-patient agreement occurred in 91% (114/125) of initial interpretations. The largest artery containing acute pulmonary embolism was segmental or larger in 24 patients (83% of patients with acute positive findings, 19% of all patients) and subsegmental in only five patients (17% and 4%, respectively). On a per-patient basis, initial interobserver agreement averaged 45% and unanimous consensus agreement was achieved for 79% of patients having isolated subsegmental pulmonary embolism. Consensus readings altered initial per-patient interpretations for 30% of patients having only subsegmental pulmonary embolism; per-embolus interpretations were altered for 37% of all subsegmental emboli. CONCLUSION: Subsegmental emboli occurring as isolated findings are relatively rare. Approximately one third of subsegmental emboli and one third of patients having isolated subsegmental emboli may be initially misdiagnosed on pulmonary angiography. Objections to cross-sectional imaging for pulmonary embolism based on the inability to detect subsegmental pulmonary embolism when compared with pulmonary angiography should be reexamined with this data in mind.