Materials and methods

We report on an experimental study with ten female pigs weighing between 25 and 30kg. The stents were randomly placed in either the right or left ureter in each of 10 study animals, for a total of 20 stented ureters. Ten ureters were stented with an R-Stent (Orbus Medical Technologies, Hoevelaken Netherlands), and ten with a Paclitaxel-Eluting Coronary Stent (Boston Scientific, Natick, MA, USA). Patency was measured by radiograph of the nephrostomy tract, intravenous urography and virtual endoscopy at 24hours and 21 days after the initial procedure, respectively.

Results

Free flow of urine through the stents into the bladder was documented in all stented ureters 24hours after stent insertion by radiograph of the nephrostomy tract. At the 21 day follow-up examination, 5 R-Stents were found to be completely occluded and two partially stenosed, whereas no occluded stent was detected in the Paclitaxel-DES group. Pathology examination of the stents at 21 days follow-up showed that the obstructed R-Stents generated severe inflammation with metaplasia of the urothelium. The Paclitaxel-Eluting MS generated a mild inflammatory response within the ureteral lumen at the site of the stent, without hindering ureteral patency. R-stents proved to develop more hyperplasia compared to the Paclitaxel-Eluting MS.

Conclusions

Paclitaxel-DES, when compared with the standard R- Stent BMS, generated less inflammation and/or hyperplasia of the surrounding tissues, thus maintaining ureteral patency. Long-term animal trials are required to further validate our results.

Evangelos N. Liatsikos^a, Dimitrios Karnabatidis^b, George C. Kagadis^c, Kostantinos Rokkas^a, Costas Constantinides^d, Nikolaos Christeas^b, Nikolaos Flaris^e, Theodore Voudoukis^a, Chrisoula D. Scopa^f, Petros Perimenis^a, Kriton S. Filos^e, George C. Nikiforidis^c, Jens-Uwe Stolzenburg^g, Dimitrios Siablis<sup>b

a</sup> Department of Urology, University of Patras, School of Medicine, Patras, Greece
^b Department of Radiology, University of Patras, School of Medicine, Patras, Greece
^c Department of Medical Physics, University of Patras, School of Medicine, Patras, Greece
^d First Department of Urology, University of Athens Medical School, ‘Laikon’ General Hospital, Athens, Greece
^e Department of Anesthesiology and Critical Care Medicine, University of Patras, School of Medicine, Patras, Greece
^f Department of Pathology, University of Patras, School of Medicine, Patras, Greece
^g Department of Urology, University of Leipzig, Germany

Accepted 31 May 2006 published online 15 June 2006.