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Title: Evaluation of Polyurethane Nasolacrimal Duct Stents: In Vivo Studies in New Zealand Rabbits

Abstract

The purpose of this study was to evaluate the radiographic and biological effects of different polyurethane nasolacrimal duct stents in an animal model. Fifteen polyurethane nasolacrimal duct stents (n = 5 mushroom-type stents, n = 5 newly designed S-shaped TearLeader stents without hydrophilic coating, and n = 5 S-shaped TearLeader stents with hydrophilic coating) were implanted in the nasolacrimal ducts of eight unaffected New Zealand rabbits. One nasolacrimal system served as control. Clinical and radiographic follow-up was performed at 1-, 2-, and 4-week intervals, then after a 3-month interval, after which the animals were euthanized. All stents were implanted without major periprocedural complications. The stents proved to be patent by the end of the procedure. During follow-up, all mushroom-type stents were occluded at 4 weeks. None of these stents opened to forced irrigation. Clinically, all rabbits demonstrated severe dacryocystitis. Three out of five TearLeader stents without hydrophilic coating were blocked at 4 weeks; one out of five was open to irrigation. Best results were observed in the stent group with hydrophilic coating. Follow-up dacryocystography demonstrated patent stents in nasolacrimal ducts of all animals after 4 weeks. In only one of five cases, the coated stent became partially occluded after 2more » months. These animals were free of clinical symptoms. After 3 months, at least three out of five stents still opened to forced irrigation and only one stent was completely blocked. Dislocation of the stents was not observed. Refinement of the stent surface and stent design improves the results of nasolacrimal duct stenting in this animal model. Implantation of hydrophilic-coated S-shaped stents is highly superior to conventional mushroom-type stents and noncoated stent types. Hydrophilic coating seems to prevent foreign-body reactions, resulting in maximized stent patency.« less

Authors:
; ;  [1];  [2];  [1];  [3]
  1. University Hospital Bonn, Department of Radiology (Germany)
  2. Clinics of the University of Bonn, Haus fuer Experimentelle Therapie (Germany)
  3. Martin Luther University of Halle-Wittenberg, Department of Anatomy and Cell Biology (Germany)
Publication Date:
OSTI Identifier:
21091137
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cardiovascular and Interventional Radiology; Journal Volume: 29; Journal Issue: 5; Other Information: DOI: 10.1007/s00270-005-0232-8; Copyright (c) 2006 Springer Science+Business Media, Inc.; www.springer-ny.com; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BIOLOGICAL EFFECTS; DISLOCATIONS; DUCTS; EVALUATION; IN VIVO; MUSHROOMS; POLYURETHANES; RABBITS

Citation Formats

Wilhelm, K.E., E-mail: wilhelm@uni-bonn.de, Grabolle, B., Urbach, H., Tolba, R., Schild, H., and Paulsen, F. Evaluation of Polyurethane Nasolacrimal Duct Stents: In Vivo Studies in New Zealand Rabbits. United States: N. p., 2006. Web. doi:10.1007/S00270-005-0232-8.
Wilhelm, K.E., E-mail: wilhelm@uni-bonn.de, Grabolle, B., Urbach, H., Tolba, R., Schild, H., & Paulsen, F. Evaluation of Polyurethane Nasolacrimal Duct Stents: In Vivo Studies in New Zealand Rabbits. United States. doi:10.1007/S00270-005-0232-8.
Wilhelm, K.E., E-mail: wilhelm@uni-bonn.de, Grabolle, B., Urbach, H., Tolba, R., Schild, H., and Paulsen, F. 2006. "Evaluation of Polyurethane Nasolacrimal Duct Stents: In Vivo Studies in New Zealand Rabbits". United States. doi:10.1007/S00270-005-0232-8.
@article{osti_21091137,
title = {Evaluation of Polyurethane Nasolacrimal Duct Stents: In Vivo Studies in New Zealand Rabbits},
author = {Wilhelm, K.E., E-mail: wilhelm@uni-bonn.de and Grabolle, B. and Urbach, H. and Tolba, R. and Schild, H. and Paulsen, F.},
abstractNote = {The purpose of this study was to evaluate the radiographic and biological effects of different polyurethane nasolacrimal duct stents in an animal model. Fifteen polyurethane nasolacrimal duct stents (n = 5 mushroom-type stents, n = 5 newly designed S-shaped TearLeader stents without hydrophilic coating, and n = 5 S-shaped TearLeader stents with hydrophilic coating) were implanted in the nasolacrimal ducts of eight unaffected New Zealand rabbits. One nasolacrimal system served as control. Clinical and radiographic follow-up was performed at 1-, 2-, and 4-week intervals, then after a 3-month interval, after which the animals were euthanized. All stents were implanted without major periprocedural complications. The stents proved to be patent by the end of the procedure. During follow-up, all mushroom-type stents were occluded at 4 weeks. None of these stents opened to forced irrigation. Clinically, all rabbits demonstrated severe dacryocystitis. Three out of five TearLeader stents without hydrophilic coating were blocked at 4 weeks; one out of five was open to irrigation. Best results were observed in the stent group with hydrophilic coating. Follow-up dacryocystography demonstrated patent stents in nasolacrimal ducts of all animals after 4 weeks. In only one of five cases, the coated stent became partially occluded after 2 months. These animals were free of clinical symptoms. After 3 months, at least three out of five stents still opened to forced irrigation and only one stent was completely blocked. Dislocation of the stents was not observed. Refinement of the stent surface and stent design improves the results of nasolacrimal duct stenting in this animal model. Implantation of hydrophilic-coated S-shaped stents is highly superior to conventional mushroom-type stents and noncoated stent types. Hydrophilic coating seems to prevent foreign-body reactions, resulting in maximized stent patency.},
doi = {10.1007/S00270-005-0232-8},
journal = {Cardiovascular and Interventional Radiology},
number = 5,
volume = 29,
place = {United States},
year = 2006,
month =
}
  • Purpose: To present our experience in the treatment of nasolacrimal occlusion by means of polyurethane stents. Methods: Forty polyurethane stents were placed under fluoroscopic guidance in 35 consecutive patients with epiphora due to total or partial obstruction of the nasolacrimal system. The set designed by Song was used in all patients. The procedure was performed by introducing a guidewire through the superior punctum into the canaliculus and advancing it across the obstruction into the inferior meatus of the nasal cavity. After pulling out the guidewire, the stent was advanced in retrograde fashion and released into the sac and the nasolacrimalmore » duct.Results: The technical success rate was 100%. The average time for the procedure was 25 min (range 10-60 min). Immediate complications were: mild pain (n= 5), severe pain (n= 1), minimal epistaxis (n= 7), and moderate epistaxis (n= 1). No major complications occurred. The last clinical control revealed complete resolution of epiphora in 35 eyes and partial resolution in four; one patient did not improve. Conclusion: This technique for treatment of obstruction of the nasolacrimal system is simple and safe, and may obviate the use of more invasive procedures.« less
  • Purpose: Prototypes of Gianturco-Rosch Z-stents coated with polycarbonate urethane (PCU) were placed in the biliary tree of pigs, in order to test their biomechanical behavior, stability, and biocompatibility. Methods: The stents were surgically implanted in the common bile duct of three pairs of pigs, which were killed after 1, 3, and 6 months respectively. Explanted livers from pigs of the same race, age, and size were used to provide comparative data. The bile ducts were radiologically and histopathologically examined; the stents were processed and examined by scanning electron microscopy. Results: No complications occurred and the animals showed a normal weightmore » gain. The main bile duct appeared radiologically and macroscopically dilated, but the stents proved to be in place. Histologically, the bile duct epithelium was destroyed, but neither hyperplastic nor inflammatory fibrotic reactions of the wall were evident. Both the metallic structure and the polymeric coating of the stents were intact. A layer of organic material with a maximum thickness of approximately 3 {mu}m was evident on the inner surface of the stents. Conclusion: The present in vivo study demonstrates the biocompatibility, efficacy, and stability of PCU-coated Gianturco-Rosch stents in the biliary environment.« less
  • Purpose: To evaluate initial results in patients with epiphora secondary to obstruction of the nasolacrimal duct treated by placement of a polyurethane stent, and to discuss the technical problems and complications arising during the procedure, with visualization of the anatomy of the drainage apparatus using computed tomography (CT). Methods: We inserted 20 polyurethane Song stents under fluoroscopic guidance after dacryocystography in 19 patients with grade 3-4 epiphora caused by idiopathic obstruction of the nasolacrimal duct. CT scans were obtained following stent placement in all patients. Results: We focus on the technical problems and complications that arose during these procedures. Duringmore » negotiation of the guidewire past the obstruction at the level of the junction of the duct with the lacrimal sac, the guidewire created a false passage in a posterior suborbital direction in two cases and towards the posterior midline in another. In all cases the guidewire was withdrawn and reinserted through the proper anatomic route without further difficulty or complications. In two cases the stent was improperly positioned wholly or partially outside the nasolacrimal system (one medially, one posteriorly). In one case the stent was removed and reinserted; in the other it remains in place and functional. CT was performed in all these cases to ensure proper anatomic alignment and determine what had gone wrong. The epiphora was completely resolved in 13 cases and partially relieved in four; there were three cases of stent obstruction. Epistaxis of short duration (1 hr) occurred in seven patients and headache in one. Conclusions: Treatment of epiphora with polyurethane stents is a technique that is well tolerated by patients and achieves a high success rate, yet problems in placement may be encountered. Though no major consequences for patients are involved, cognizance of such difficulties is important to avoid incorrect positioning of stents.« less
  • Purpose: To evaluate the long-term mechanical behavior in vivo of expandable endobronchial wire stents, we imaged three different prostheses in the treatment of tracheobronchial disease. Methods: Six patients with bronchial stenoses (three benign, three malignant) underwent insertion of metallic stents. Two self-expandable Wallstents, two balloon-expandable tantalum Strecker stents and two self-expandable nitinol Accuflex stents were used. Measurements of deformation properties were performed during voluntary cough by means of fluoroscopy, at 1 month and 7-10 months after implantation. The procedures were videotaped, their images digitized and the narrowing of stent diameters calculated at intervals of 20 msec. Results: After stent implantationmore » all patients improved with respect to ventilatory function. Radial stent narrowing during cough reached 53% (Wallstent), 59% (tantalum Strecker stent), and 52% (nitinol Accuflex stent) of the relaxed post-implantation diameter. Stent compression was more marked in benign compared with malignant stenoses. In the long term permanent deformation occurred with the tantalum Strecker stents; the other stents were unchanged. Conclusion: Endobronchial wire stents can be helpful in the treatment of major airway collapse and obstructing bronchial lesions. However, evidence of material fatigue as a possible effect of exposure to recurrent mechanical stress on the flexible mesh tube may limit their long-term use. This seems to be predominantly important in benign bronchial collapse.« less