title: A new optional vena cava filter: retrieval at 12 weeks in an animal model.
abstract: OBJECTIVE
  To test the feasibility and safety of percutaneous retrieval of a new inferior vena cava (IVC) filter, the Recovery Filter (RF), acutely and after 12-week implantation in sheep.
  
  
  METHODS
  The RF is a bilevel filter with stabilizing arms and elastic hooks that allow retrieval with a unique retrieval cone after incorporation into the wall of the IVC. Twenty-four filters were placed in the infrarenal IVCs of 18 sheep. In six sheep, two filters were placed and then removed immediately; three sheep were killed acutely and three were killed after a healing period of 3 weeks. In 12 sheep, a single filter was placed and then removed 12 weeks later; six were killed after retrieval and six were killed after an 8-week healing period.
  
  
  RESULTS
  The mean (+/-SD) transverse vena caval diameter was 15.3 mm +/- 2. All filters were deployed as intended and retrieved without difficulty. At sacrifice, there was no evidence of IVC perforation or retroperitoneal abnormality. The IVCs of the animals in the acute retrieval group showed minimal acute superficial injury that was largely reversed at 3 weeks. At 12 weeks, there was evidence of transmural incorporation of filter elements with narrowing of the IVCs. Solitary fibrotic abnormalities were present in the aorta adjacent to IVC lesions in nine of the 12 animals in the 12-week group. The IVC and aortic abnormalities were largely healed, with reversal of IVC narrowing after 8 weeks.
  
  
  CONCLUSIONS
  The recovery filter can be reliably and safely retrieved acutely and 12 weeks after implantation in sheep.
authors.affiliation: Second Department of Radiology, Medical School, University of Athens, Greece.
authors.forename: Elias N
authors.initials: EN
authors.lastname: Brountzos
authors.forename: John A
authors.initials: JA
authors.lastname: Kaufman
authors.forename: Anthony C
authors.initials: AC
authors.lastname: Venbrux
authors.forename: P Rand
authors.initials: PR
authors.lastname: Brown
authors.forename: Jason
authors.initials: J
authors.lastname: Harry
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Kinst
authors.forename: Stephen
authors.initials: S
authors.lastname: Kleshinski
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Ravenscroft
mesh_terms: D000818:Animals; D001011:Aorta / Q000473:pathology / Q000601:surgery; D020878:Device Removal; D004195:Disease Models, Animal; D004869:Equipment Safety; D005240:Feasibility Studies; D005260:Female; D005500:Follow-Up Studies; D008955:Models, Cardiovascular; D010690:Phlebography; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000209:etiology / Q000503:physiopathology; D011474:Prosthesis Design; D019919:Prosthesis Implantation; D012756:Sheep; D013997:Time Factors; D014654:Vascular Patency / Q000502:physiology; D016306:Vena Cava Filters; D014682:Vena Cava, Inferior / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery