title: Obstruction of the lacrimal system: treatment with a covered, retrievable, expandable nitinol stent versus a lacrimal polyurethane stent.
abstract: OBJECTIVE
  To compare the clinical effectiveness of a covered nitinol stent with that of a polyurethane stent for treatment of lacrimal system obstructions.
  
  
  METHODS
  A nitinol stent was knit from a single thread of 0.1-mm nitinol wire in a tubular configuration and was covered by dipping the stent into a polyurethane solution. The stent was 4 mm in diameter and 30 or 35 mm long. With fluoroscopic guidance, a covered nitinol stent (n = 33, group A) or a polyurethane stent (n = 35, group B) was placed in 68 patients. The following items were evaluated retrospectively: technical success, procedure time, cumulative patency rate, and complications. An unpaired Student t test was used to analyze the difference between the procedure times. Kaplan-Meier survival curves and a log-rank test were used to compare the cumulative patency rates.
  
  
  RESULTS
  Stent placement was technically successful in 31 (94%) of 33 patients in group A and in all 35 (100%) patients in group B. After stent placement, all patients showed resolution of epiphora. Average procedure time was 400 seconds (range, 270-900 seconds) in group A and 260 seconds (range, 150-900 seconds) in group B. The difference between the procedure times was statistically significant (P =.0003). During the mean follow-up period of 40 months, there was recurrence of epiphora in 30 of 31 patients in group A and 26 of 35 patients in group B. The difference of the cumulative patency rates was statistically insignificant (P =.2).
  
  
  CONCLUSIONS
  Although the polyurethane stent used for treatment seemed to be more effective than the nitinol stent, selection of these stents for placement should be made with caution, because the long-term patency rates are not encouraging.
authors.affiliation: Department of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1 Poongnap-Dong, Songpa-Ku, Seoul 138-736, Korea.
authors.forename: Gi-Young
authors.initials: GY
authors.lastname: Ko
authors.forename: Ho-Young
authors.initials: HY
authors.lastname: Song
authors.forename: Tae-Seok
authors.initials: TS
authors.lastname: Seo
authors.forename: Tae-Hyung
authors.initials: TH
authors.lastname: Kim
authors.forename: Kyu-Bo
authors.initials: KB
authors.lastname: Sung
authors.forename: Hyun-Ki
authors.initials: HK
authors.lastname: Yoon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000497:Alloys; D004867:Equipment Design; D004868:Equipment Failure; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007767:Lacrimal Duct Obstruction / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D011140:Polyurethanes; D012008:Recurrence; D015607:Stents
chemical_list: D000497:Alloys; D011140:Polyurethanes; C013616:nitinol