title: Impact of reducing duodenobiliary reflux on biliary stent patency: an in vitro evaluation and a prospective randomized clinical trial that used a biliary stent with an antireflux valve.
abstract: BACKGROUND
  The mechanisms leading to occlusion of plastic biliary stents (PBS) are not known.
  
  
  OBJECTIVE
  To evaluate the impact of reducing duodenobiliary reflux on stent patency rate.
  
  
  METHODS
  A newly designed antireflux PBS (AR-PBS) was tested in vitro by using ox bile. A prospective randomized trial in human beings was conducted.
  
  
  METHODS
  Tertiary medical center.
  
  
  METHODS
  Patients with malignant bile-duct strictures were studied.
  
  
  METHODS
  A PBS or an AR-PBS stent was placed by using standard techniques, and the patients were followed at regular intervals. Patients presenting with stent occlusion underwent re-stent placement with either a PBS or a metal stent.
  
  
  METHODS
  In vitro: resistance to retrograde flow and comparison of the basal and peak antegrade flow pressures between the 2 stents. In vivo: stent patency rates, complications, and the efficacy of the stents in improving the liver test.
  
  
  RESULTS
  The AR-PBS stent could withstand a retrograde pressure gradient of >320 mm Hg compared with <1 mm Hg for the PBS. Secondary to the siphon effect of the valve, the antegrade flow resistance offered by the AR-PBS was on the negative side for all flow rates compared with PBS (P < .001). The median patency of the AR-PBS in human studies was 145 days (range, 52-252 days) compared with 101 days (range, 41-210 days) for the PBS (P = .002). Both stents were equally effective in improving the liver test, and complication rates were similar in the 2 groups.
  
  
  CONCLUSIONS
  The occluded stents were not examined microscopically.
  
  
  CONCLUSIONS
  The antireflux biliary stent remains patent for a longer time and hence duodenobiliary reflux may be contributing to stent occlusion.
authors: Pancreatico-biliary Center, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors: Kulwinder S
authors: KS
authors: Dua
authors: Nageshwar D
authors: ND
authors: Reddy
authors: Venkat G
authors: VG
authors: Rao
authors: Rupa
authors: R
authors: Banerjee
authors: Bidyut
authors: B
authors: Medda
authors: Ivan
authors: I
authors: Lang
mesh_terms: D000818:Animals; D001655:Bile Reflux / Q000601:surgery*; D001659:Biliary Tract / Q000503:physiopathology; D002417:Cattle; D002779:Cholestasis / Q000601:surgery*; D003251:Constriction, Pathologic; D004322:Drainage / Q000295:instrumentation; D004867:Equipment Design; D004868:Equipment Failure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012212:Rheology; D015607:Stents / Q000009:adverse effects / Q000592:standards