title: Vena cava filter performance based on hemodynamics and reported thrombosis and pulmonary embolism patterns.
abstract: OBJECTIVE
  Three inferior vena cava (IVC) filters of different designs were studied to identify the potential links between published clinical results for thrombosis and recurrent pulmonary embolism (PE) rates and in vitro hemodynamics patterns in the region of the filters.
  
  
  METHODS
  The filters studied were the Greenfield over-the-wire filter (Medi-tech/Boston Scientific, Watertown, Mass), TrapEase filter (Cordis Europa, Roden, the Netherlands), and Mobin-Uddin umbrella filter (Edwards Laboratories, Santa Ana, Calif). To assess hemodynamics, velocity contour maps were generated for each filter by using the in vitro photochromic flow visualization technique. Results were obtained for both the unoccluded and partially occluded states. Steady flow (R(e) = 600) was used to model physiologic conditions. To estimate the rates of IVC occlusion and recurrent PE, the authors analyzed published clinical studies spanning more than 30 years and a U.S. Food and Drug Administration database.
  
  
  RESULTS
  For both the unoccluded and partially occluded Mobin-Uddin and TrapEase filters, regions of flow stagnation and/or recirculation and turbulence developed downstream of the filter. The Greenfield filter did not produce any prothrombotic flow patterns for either the unoccluded or partially occluded states. Results of published clinical studies supported the hemodynamic findings, with the TrapEase and Mobin-Uddin filters having high rates of IVC occlusion and recurrent PE compared with those of the Greenfield filter.
  
  
  CONCLUSIONS
  Flow stagnation or recirculation and turbulence have been linked to thrombosis and thrombus and/or PE formation. Thus, the hemodynamic results from this study may help explain the relatively higher rates of filter thrombosis and PE for the Mobin-Uddin and TrapEase filters versus the Greenfield filter.
authors.affiliation: Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Aneal
authors.initials: A
authors.lastname: Harlal
authors.forename: Matadial
authors.initials: M
authors.lastname: Ojha
authors.forename: K Wayne
authors.initials: KW
authors.lastname: Johnston
mesh_terms: D001783:Blood Flow Velocity; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D011655:Pulmonary Embolism / Q000209:etiology / Q000517:prevention & control*; D013927:Thrombosis / Q000209:etiology*; D016306:Vena Cava Filters / Q000009:adverse effects