title: Removal of the OptEase retrievable vena cava filter is not feasible after extended time periods because of filter protrusion through the vena cava.
abstract: BACKGROUND
  Therapeutic and prophylactic vena cava filters (VCFs) are used to prevent pulmonary embolism. Concerns exist over placing a permanent filter in a young trauma patient. Recently, retrievable VCFs have become available. One such filter is the OptEase, which has a recommended time of removal of up to 23 days after insertion. Data supporting this recommendation are sparse. Many trauma patients will need filters for more than 2 weeks, and there are no data evaluating the safety of removal after extended time periods. The purpose of this study was to determine the safety, feasibility, and reaction of the vena cava when removing the OptEase retrievable VCF at different time intervals.
  
  
  METHODS
  Twenty Yorkshire cross pigs (80-113 kg) underwent general anesthesia with tiletamine and zolazepam. Filters were placed in the infrarenal vena cava (VC) through the femoral vein under fluoroscopic guidance. Animals were then divided into four groups. In group 1, filters were removed at 14 days; in group 2, at 30 days; in group 3, at 60 days; and in group 4, at 90 days. Removal was attempted using a snare-and-sheath technique through the femoral vein. Animals with successful filter removal were allowed to recover; then, the animals underwent autopsy (gross and microscopic VC examination) 2 months later. Animals with unsuccessful filter removal underwent autopsy immediately after attempted removal. Venacavograms were taken at filter insertion, at removal, and before autopsy to evaluate any VC abnormalities.
  
  
  RESULTS
  Successful removal of the filter in all five pigs (100%) was reliably performed only in the 14-day group. In this group, the initial VC transverse diameter was 19.4 +/- 0.8 mm and was significantly reduced to 9.8 +/- 1.1 mm (p < 0.05) immediately after removal. Sixty days later, before autopsy, VC diameter had increased to 15.3 +/- 1.9 mm, which was significantly larger than at removal (p < 0.05) but not different from the initial value. In the 30-day group, removal was successful in only one of five animals. Although removal was successful in the one pig, autopsy at 2 months postremoval revealed total occlusion of the VC. Filters could not be removed from 60- and 90-day groups. At autopsy, the VCF struts were embedded or protruded through the VC wall. Microscopic examination of the VC revealed significant scarring underneath and between the struts.
  
  
  CONCLUSIONS
  Removal of the retrievable OptEase VCF may be successfully performed up to 14 days after insertion. Strut protrusion through the VC wall prohibited successful and safe removal at extended time intervals.
authors.affiliation: Medical Center of Central Georgia, Fort Valley State University, Mercer University School of Medicine, Macon, 31201, USA. Ashley.dennis@mccg.org
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Ashley
authors.forename: J William
authors.initials: JW
authors.lastname: Mix
authors.forename: Benjamin
authors.initials: B
authors.lastname: Christie
authors.forename: Charles G
authors.initials: CG
authors.lastname: Burton
authors.forename: Frank K
authors.initials: FK
authors.lastname: Lochner
authors.forename: George W
authors.initials: GW
authors.lastname: McCommon
authors.forename: George C
authors.initials: GC
authors.lastname: Matoy
authors.forename: Maurice M
authors.initials: MM
authors.lastname: Solis
authors.forename: Robert S
authors.initials: RS
authors.lastname: Donner
authors.forename: Martin L
authors.initials: ML
authors.lastname: Dalton
authors.forename: Clary S
authors.initials: CS
authors.lastname: Tyson
authors.forename: Walter H
authors.initials: WH
authors.lastname: Newman
mesh_terms: D000818:Animals; D004868:Equipment Failure; D011655:Pulmonary Embolism / Q000209:etiology / Q000517:prevention & control*; D013552:Swine; D013997:Time Factors; D016306:Vena Cava Filters; D014682:Vena Cava, Inferior / Q000293:injuries* / Q000473:pathology; D020246:Venous Thrombosis / Q000150:complications*