title: Viscoelastic property mapping along encrusted polymeric urinary catheters.
abstract: OBJECTIVE
  Mapping of the material viscoelastic property variation along the length axis of polymeric stents.
  
  
  METHODS
  Five pigtail ureteral stents and five percutaneous stents placed in vivo for different periods were studied. Viscoelastic property changes along the length of polymeric stents were measured using the dynamic mechanical analysis technique. The type of encrustations was identified using FT-IR spectroscopy and their morphology by scanning electron microscopy (SEM).
  
  
  RESULTS
  Variations in viscoelastic stiffness were confirmed for both types of stents. In a few cases, the variation was quite large (400%). Various encrustation types and/or organic sheathing of the salt were found to be responsible for this effect. In detail, calcium oxalate monohydrate (COM) plaques for percutaneous and COM/organic layer for pigtail stents were recognized by FT-IR spectroscopy and SEM observation to invoke reinforcing effects along the stent axes.
  
  
  CONCLUSIONS
  The phenomenon of stiffness variation along the stent axes requires further study to understand the mechanism behind it and consequently to improve the biomaterial and design of specific areas of stents as well as to avoid encrustations. This further research might lead in the near future to the development of new types of polymer stents for drug-eluting specialized areas.
authors: Department of Material Science, University of Patras, Patras, Greece.
authors: Dionysios E
authors: DE
authors: Mouzakis
authors: Nikolaos
authors: N
authors: Bouropoulos
authors: Panagiotis
authors: P
authors: Kallidonis
authors: Dimitrios
authors: D
authors: Karnabatidis
authors: Konstantinos
authors: K
authors: Katsanos
authors: Constantinos
authors: C
authors: Constantinidis
authors: Petros
authors: P
authors: Perimenis
authors: Dimitrios
authors: D
authors: Siamblis
authors: Evangelos N
authors: EN
authors: Liatsikos
mesh_terms: D000818:Animals; D004548:Elasticity; D006801:Humans; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D015607:Stents; D013552:Swine; D014546:Urinary Catheterization; D014783:Viscosity
chemical_list: D011108:Polymers