title: Placement of a spring filter during interventional treatment of deep venous thrombosis to reduce the risk of pulmonary embolism.
abstract: OBJECTIVE
  To assess the efficacy of the Spring filter during interventional treatment of deep venous thrombosis in vivo.
  
  
  METHODS
  A model of inferior vena cava thrombosis was used. Part I: The thrombus was treated by the pulse-spray technique (PT) (urokinase 250,000 IU; n=7) or a rotatory basket catheter, Thrombolizer (MT) (activated with compressed air at 7 atm; n=5). Part II: Following placement of a Spring filter, the animal underwent PT (n=5) or MT (n=5). Based on the results of part I, the treatment protocol was modified (PT, urokinase 500,000 IU; MT, compressed air at 8 atm). Embolus volumes trapped by the filter and found in the lungs were calculated and the filtering efficacy quantified.
  
  
  RESULTS
  Part I: Pulmonary emboli (1 to 4 mm in diameter) were observed in 3 animals in the PT group and 1 animal in the MT group, respectively. Median reduction in thrombus volume was 21% and 4% by PT and MT, respectively. Part II: In the PT group, 58% and 100% of the total embolus load was trapped in 2 animals, while the filter failed to trap emboli (1 to 1.5 mm in diameter) in 1 animal. In the remaining 2 animals, no embolus was found trapped by the filter or in the lungs. In the MT group, 55 97% (median 83%) of the embolus load was trapped. Emboli found in the lungs did not exceed 4 mm in diameter.
  
  
  CONCLUSIONS
  Preceding interventional treatment of venous thrombosis with placement of the Spring filter reduced the embolic burden on the lungs.
authors.affiliation: Section for Experimental Radiology, Institute for Surgical Research, The National Hospital, Oslo, Norway.
authors.forename: J
authors.initials: J
authors.lastname: Hosaka
authors.forename: S
authors.initials: S
authors.lastname: Roy
authors.forename: K
authors.initials: K
authors.lastname: Kuroki
authors.forename: Z
authors.initials: Z
authors.lastname: Xian
authors.forename: K
authors.initials: K
authors.lastname: Kvernebo
authors.forename: I
authors.initials: I
authors.lastname: Enge
authors.forename: F
authors.initials: F
authors.lastname: Laerum
mesh_terms: D000792:Angiography; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage; D007275:Injections, Intravenous; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D013552:Swine; D017131:Thrombectomy / Q000379:methods*; D015912:Thrombolytic Therapy / Q000379:methods*; D016896:Treatment Outcome; D016306:Vena Cava Filters; D014682:Vena Cava, Inferior; D020246:Venous Thrombosis / Q000150:complications / Q000000981:diagnostic imaging / Q000628:therapy*
chemical_list: D005343:Fibrinolytic Agents