Viscoelastic Property Mapping along Encrusted Polymeric Urinary Catheters.

PurposeMapping of the material viscoelastic property variation along the length axis of polymeric stents.Materials and MethodsFive 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).ResultsVariations in viscoelastic stiffness were confirmed for both types of stents. In a few cases, the variation was quite large (400). Various encrustation types andor organic sheathing of the salt were found to be responsible for this effect. In detail, calcium oxalate monohydrate (COM) plaques for percutaneous and COMorganic layer for pigtail stents were recognized by FT-IR spectroscopy and SEM observation to invoke reinforcing effects along the stent axes.ConclusionsThe 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. [ABSTRACT FROM AUTHOR]