title: Complex retrieval of fractured, embedded, and penetrating inferior vena cava filters: a prospective study with histologic and electron microscopic analysis.
abstract: OBJECTIVE
  To evaluate clinical outcomes, characterize adherent tissue, and analyze inferior vena cava (IVC) filter fractures in patients undergoing complex retrieval for management of filter-related complications. To elucidate mechanisms of filter fracture by radiographic and electron microscopic (EM) evaluation.
  
  
  METHODS
  Over 2.5 years, 50 consecutive patients with fractured and/or penetrating filter components were prospectively enrolled into a single-center study. There were 19 men and 31 women (mean age, 42 y; range, 15-73 y). All patients underwent complex filter retrieval after failure of standard methods, and retrieval indications along with resultant clinical outcomes were evaluated. Specimens with adherent tissue underwent histologic analysis, and all fractured components were studied with EM.
  
  
  RESULTS
  Retrieval was successful in all 50 cases (mean implantation, 815 d; range, 20-2,599 d) among the following filters: G2X (n = 23),G2 (n = 9), Eclipse (n = 3), Recovery (n = 4), ALN (n = 1), Celect (n = 7), OptEase (n = 2), and Simon Nitinol (n = 1). Mean indwell time in fractured filters (n = 31) was 1,082 days, versus 408 days in nonfractured filters (n = 19; P = .00169). Neointimal hyperplasia/fibrosis was seen in 46 of 48 specimens with adherent tissue (96%). Among 61 fractured components from conical filters, 35 had extravascular penetration whereas 26 remained intravascular (11 free-floating in IVC, 15 embolized centrally), and EM revealed fracture modes of high-cycle fatigue (n = 53), overload (n = 6), and indeterminate (n = 2). Following retrieval, previously prescribed lifelong anticoagulation was discontinued in 30 of 31 patients (97%). Filter-related symptoms from IVC occlusion, component embolization, and penetration-induced abdominal pain, duodenal injury, and/or small-bowel volvulus were alleviated in all 26 cases (100%). There were no long-term complications at a mean follow-up of 371 days (range, 67-878 d).
  
  
  CONCLUSIONS
  The risk of filter fracture increases after 408 days (ie,>1 y) of implantation and is associated with symptomatic extravascular penetration and/or intravascular embolization. Complex methods can be used to safely remove these devices, alleviate filter-related morbidity, and allow cessation of anticoagulation.
authors.affiliation: Division of Vascular and Interventional Radiology/Department of Radiology, Stanford University Medical Center, Stanford, CA 94305, USA. wkuo@stanford.edu
authors.forename: William T
authors.initials: WT
authors.lastname: Kuo
authors.forename: Scott W
authors.initials: SW
authors.lastname: Robertson
authors.forename: Justin I
authors.initials: JI
authors.lastname: Odegaard
authors.forename: Lawrence V
authors.initials: LV
authors.lastname: Hofmann
mesh_terms: D000293:Adolescent; D000328:Adult; D020878:Device Removal / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000293:injuries* / Q000473:pathology; D011655:Pulmonary Embolism / Q000150:complications / Q000473:pathology / Q000601:surgery*; D016896:Treatment Outcome; D057772:Vascular System Injuries / Q000209:etiology* / Q000473:pathology / Q000601:surgery*; D016306:Vena Cava Filters / Q000009:adverse effects*; D014950:Wounds, Penetrating / Q000209:etiology* / Q000473:pathology; D055815:Young Adult