title: Evaluation of a Polymeric Flap Valve-Attached Ureteral Stent for Preventing Vesicoureteral Reflux in Elevated Intravesical Pressure Conditions: A Pilot Study Using a Porcine Model.
abstract: OBJECTIVE
  To evaluate the effectiveness of a polymeric flap valve-attached ureteral stent for preventing vesicoureteral reflux (VUR) in an animal model.
  
  
  METHODS
  One female Yorkshire pig was included in this study. A flap valve-attached and a conventional stent was inserted in the right and left ureters, respectively. The bladder was filled with contrast medium until the intravesical pressure reached 20 cm H2O. Subsequently, simulated voiding cystourethrography (VCUG) was performed 50 times by manually compressing the suprapubic area until the intravesical pressure reached 50 cm H2O. Intravenous pyelography (IVP) was performed thereafter to evaluate the urinary drainage. In addition, an in vitro durability test of the function of the flap valve was conducted under continuous hydrostatic pressure for 24 h.
  
  
  RESULTS
  The volume of contrast medium needed to achieve an intravesical pressure of 20 cm H2O was 1740 mL. In the repeated simulated VCUG for the right ureter, VUR grades of 0 and I were recorded in 82.0 (n = 41) and 18.0% (n = 9) tests, respectively, whereas for the left ureter, grades of I, II, and III were recorded in 14.0 (n = 7), 82.0 (n = 41), and 4.0% (n = 2), respectively. Thus, a significantly lower VUR grade was recorded for the right ureter than for the left ureter (p < 0.001). In the bilateral VUR condition, the pressure for VUR occurrence was significantly greater in the right ureter than in the left ureter (p = 0.007). No urinary obstruction was caused by the flap valve-attached ureteral stent according to the IVP findings. The in vitro durability test demonstrated slightly enhanced antireflux function and slightly decreased intraluminal drainage at 12 h, and these findings sustained thereafter.
  
  
  CONCLUSIONS
  A flap valve-attached ureteral stent effectively prevented VUR under conditions of elevated intravesical pressure without urinary obstruction.
authors.affiliation: 1 Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju, South Korea .
authors.forename: Hyeon Woo
authors.initials: HW
authors.lastname: Kim
authors.affiliation: 1 Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju, South Korea .
authors.forename: Chang-Ju
authors.initials: CJ
authors.lastname: Park
authors.affiliation: 2 School of Mechatronics, Gwangju Institute of Science and Technology (GIST) , Gwangju, South Korea .
authors.forename: Seungwan
authors.initials: S
authors.lastname: Seo
authors.affiliation: 1 Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju, South Korea .
authors.forename: Yangkyu
authors.initials: Y
authors.lastname: Park
authors.affiliation: 3 Department of Urology, Pusan National University Hospital , Busan, South Korea .
authors.forename: Jeong Zoo
authors.initials: JZ
authors.lastname: Lee
authors.affiliation: 3 Department of Urology, Pusan National University Hospital , Busan, South Korea .
authors.forename: Dong Gil
authors.initials: DG
authors.lastname: Shin
authors.affiliation: 4 Department of Urology, Hanyang University Guri Hospital , Guri, South Korea .
authors.forename: Hong Sang
authors.initials: HS
authors.lastname: Moon
authors.affiliation: 1 Department of Medical System Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju, South Korea .|2 School of Mechatronics, Gwangju Institute of Science and Technology (GIST) , Gwangju, South Korea .
authors.forename: Jong-Hyun
authors.initials: JH
authors.lastname: Lee
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D010865:Pilot Projects; D011312:Pressure; D015607:Stents; D013552:Swine; D014513:Ureter / Q000601:surgery; D014516:Ureteral Neoplasms / Q000601:surgery*; D014567:Urography; D014718:Vesico-Ureteral Reflux / Q000601:surgery*