title: [Experimental study of esophageal covered stent for prevention of migration: use of clay to simulate stenosis of the esophagogastric junction or anastomosis site].
abstract: OBJECTIVE
  An inner-covered Spiral Z-stent (IC-SZ) developed by our group was examined for its effectiveness in preventing migration by experimental comparison with commercially available esophageal covered stents.
  
  
  METHODS
  The following six types of stents were used: inner-covered Spiral Z-stents with diameters of 16 mm (small IC-SZ) and 19 mm (large IC-SZ), outer-covered Spiral Z-stent (OC-SZ), covered Wallstent, covered Ultraflex stent, and Cook Z-stent. Experimental models were prepared using clay to simulate stenosis of the esophagogastric junction or anastomosis site due to tumor, and each stent was placed in the clay. After the stent had been fully expanded with a balloon catheter, one of its ends was pulled until the stent migrated out of the clay, and the traction force was measured. The inner cavity of the stent placed in the clay was observed using an endoscope.
  
  
  RESULTS
  The mean maximal traction force required to pull the stents out of the clay were as follows, in decreasing order: 4.14 +/- 0.39 kg for the large IC-SZ, 4.12 +/- 0.83 kg for the small IC-SZ, 3.64 +/- 0.44 kg for the Cook Z-stent (p < 0.05), 3.34 +/- 0.62 kg for the covered Ultraflex stent (p < 0.05), 1.53 +/- 0.43 kg for the OC-SZ (p < 0.01), and 0.56 +/- 0.16 kg for the covered Wallstent (p < 0.01). The force required to pull out the large IC-SZ stent was the greatest, showing a significant difference from the values for the other four types of stents (excluding the small IC-SZ). Observation using an endoscope revealed that the wire of the IC-SZ stent was almost entirely embedded in the clay, whereas the wires of other stents were not.
  
  
  CONCLUSIONS
  The IC-SZ stent may be less likely to migrate than other esophageal covered stents.
authors.affiliation: Department of Radiology, Higashiosaka City General Hospital.
authors.forename: S
authors.initials: S
authors.lastname: Makutani
authors.forename: T
authors.initials: T
authors.lastname: Yoshioka
authors.forename: H
authors.initials: H
authors.lastname: Uchida
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.forename: H
authors.initials: H
authors.lastname: Yoshimura
authors.forename: H
authors.initials: H
authors.lastname: Ohishi
authors.forename: S
authors.initials: S
authors.lastname: Iwasaki
authors.forename: K
authors.initials: K
authors.lastname: Ide
authors.forename: K
authors.initials: K
authors.lastname: Ueda
authors.forename: M
authors.initials: M
authors.lastname: Maeda
mesh_terms: D001696:Biomechanical Phenomena; D004940:Esophageal Stenosis / Q000503:physiopathology / Q000628:therapy*; D004943:Esophagogastric Junction; D006801:Humans; D008567:Membranes, Artificial; D008953:Models, Anatomic; D011095:Polyethylenes; D011475:Prosthesis Failure; D012828:Silicones; D015607:Stents
chemical_list: D008567:Membranes, Artificial; D011095:Polyethylenes; D012828:Silicones