title: Mechanisms of Günther Tulip filter tilting during transfemoral placement.
abstract: OBJECTIVE
  The purpose of this study was to characterize the mechanisms of Günther Tulip filter (GTF) tilting during transfemoral placement in an experimental model with further validation in a clinical series.
  
  
  METHODS
  In an experimental study, 120 GTF placements in an inferior vena cava (IVC) model were performed using 6 configurations of pre-deployment filter position. The angle between the pre-deployment filter axis and IVC axis, and the proximity of the constrained filter legs to IVC wall prior to deployment were evaluated. The association of those pre-deployment factors with post-deployment filter tilting was analyzed. The association noted in the experimental study was then evaluated in a retrospective clinical series of 21 patients.
  
  
  RESULTS
  In the experimental study, there was a significant association between the pre-deployment angle and post-deployment filter tilting (P<0.0001). With a low pre-deployment angle (≤5°), a significant association was noted between filter tilting and the proximity of the constrained filter legs to the far IVC wall (P=0.001). In a retrospective clinical study, a significant association between the pre-deployment angle and post-deployment filter tilting was also noted with a linear regression model (P=0.026).
  
  
  CONCLUSIONS
  Significant association of the pre-deployment angle with post-deployment GTF tilting was shown in both the experimental and clinical studies. The experimental study also showed that proximity of filter legs is relevant when pre-deployment angle is small. Addressing these factors may result in a lower incidence of filter tilting.
authors.affiliation: Dotter Interventional Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA; Department of Radiology, Okayama University Medical School, 2-5-1 Sikata-cho, Kita-ku, Okayama 700-8558, Japan. Electronic address: y-matsui@okayama-u.ac.jp.
authors.forename: Y
authors.initials: Y
authors.lastname: Matsui
authors.affiliation: Dotter Interventional Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA.
authors.forename: M
authors.initials: M
authors.lastname: Horikawa
authors.affiliation: Dotter Interventional Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA; Department of Radiology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Ohta
authors.affiliation: Dotter Interventional Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Jahangiri Noudeh
authors.affiliation: Dotter Interventional Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Kaufman
authors.affiliation: Dotter Interventional Institute, Oregon Health and Science University, 3181 SW Sam Jackson Park Rd, Portland, OR 97239, USA.
authors.forename: K
authors.initials: K
authors.lastname: Farsad
keywords: Experimental studies; Inferior vena cava; Inferior vena cava filter; Interventional imaging