A new SWL titanium stent (Zebra Stent): resistance to shockwave exposure.
OBJECTIVE
Recently, a new-concept lumen-less Teflon-coated double-J wire stent (Zebra stent) has been introduced to facilitate residual stone clearance, in particular after SWL. Its metal core expresses highly mismatched acoustic impedance. It was the aim of this study to exclude damage to the stent through shockwaves. Also, its Teflon coating should to some degree prevent encrustation, and stents removed from stone formers were examined for encrustation.


METHODS
Series of 2000 shockwaves of an average and a maximum energy were applied to defined areas of Zebra stents in a waterbath on a Siemens Multiline Lithotriptor. Stents were then examined for core and sheath damage by digital photography, scanning electron microscopy, and microradiography. In addition, two Zebra stents and one conventional double-J stent from two stone formers were assessed in the same way for damage and encrustation.


RESULTS
There was no damage whatsoever to either of the stents. Whereas there was considerable encrustation on the conventional double-J stent, there was none on the Zebra stents after 4 and 5 weeks in situ.


CONCLUSIONS
Zebra stents resist shockwaves to a maximum number and energy sufficiently to be applied safely under SWL. Whether they resist encrustation to a higher degree in the short term than conventional stents remains to be established.
Departments of Urology, Barts and The London NHS Trust, London, UK. nielspeter@yahoo.com
Noor N P
NN
Buchholz
Clive
C
Cannaby
Ruby
R
Fong
Andrew
A
Gray
Henry O
HO
Andrews
Malcolm J
MJ
Birch
D006801:Humans; D066298:In Vitro Techniques; D008096:Lithotripsy; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D011138:Polytetrafluoroethylene; D015607:Stents; D014025:Titanium; D014545:Urinary Calculi / Q000628:therapy*
D011138:Polytetrafluoroethylene; D014025:Titanium