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Title: Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters

Abstract

The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30-40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15more » weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted.« less

Authors:
; ;  [1];  [2];  [3];  [4]; ;  [5]
  1. Ansan Hospital, Korea University College of Medicine, Department of Radiology (Korea, Republic of)
  2. Korea University, Ansan Hospital, Department of Urology (Korea, Republic of)
  3. Korea University, Ansan Hospital, Department of Pathology (Korea, Republic of)
  4. Ewha Women's University, Mokdong Hospital, Department of Radiology (Korea, Republic of)
  5. Stanford University Medical Center, Department of Vascular and Interventional Radiology (United States)
Publication Date:
OSTI Identifier:
21094170
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cardiovascular and Interventional Radiology; Journal Volume: 31; Journal Issue: 3; Other Information: DOI: 10.1007/s00270-007-9087-5; Copyright (c) 2008 Springer Science+Business Media, LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; BIOMEDICAL RADIOGRAPHY; DOGS; PHENOBARBITAL; POLYTETRAFLUOROETHYLENE; URETERS; VASCULAR DISEASES

Citation Formats

Chung, Hwan-Hoon, E-mail: chungmic@korea.ac.kr, Lee, Seung Hwa, Cho, Sung Bum, Park, Hong Suk, Kim, Young Sik, Kang, Byung Chul, Frisoli, Joan K., and Razavi, Mahmood K. Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters. United States: N. p., 2008. Web. doi:10.1007/S00270-007-9087-5.
Chung, Hwan-Hoon, E-mail: chungmic@korea.ac.kr, Lee, Seung Hwa, Cho, Sung Bum, Park, Hong Suk, Kim, Young Sik, Kang, Byung Chul, Frisoli, Joan K., & Razavi, Mahmood K. Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters. United States. doi:10.1007/S00270-007-9087-5.
Chung, Hwan-Hoon, E-mail: chungmic@korea.ac.kr, Lee, Seung Hwa, Cho, Sung Bum, Park, Hong Suk, Kim, Young Sik, Kang, Byung Chul, Frisoli, Joan K., and Razavi, Mahmood K. 2008. "Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters". United States. doi:10.1007/S00270-007-9087-5.
@article{osti_21094170,
title = {Comparison of a New Polytetrafluoroethylene-Covered Metallic Stent to a Noncovered Stent in Canine Ureters},
author = {Chung, Hwan-Hoon, E-mail: chungmic@korea.ac.kr and Lee, Seung Hwa and Cho, Sung Bum and Park, Hong Suk and Kim, Young Sik and Kang, Byung Chul and Frisoli, Joan K. and Razavi, Mahmood K.},
abstractNote = {The aim of this study was to determine the feasibility of using a newly designed polytetrafluoroethylene (PTFE)-covered metallic stent in the ureter by comparing its effectiveness with that of the noncovered stent in a canine model. We placed 14 stents in the ureters of seven mongrel dogs that weighed 30-40 kg each. The covered and noncovered stents were deployed in the right and left ureters, respectively, of six dogs. In the seventh dog, a covered stent and a double-J catheter were inserted in the right ureter, and a covered stent only was inserted in the left ureter. The first six dogs were sacrificed at 5, 10, and 15 weeks after deployment of the stents (two for each follow-up period), and the seventh dog was sacrificed at 30 weeks. There was no migration or poor expansion of any of the stents observed on plain radiography. On intravenous pyelogram and retrograde pyelogram, all of the covered stents at each follow-up period had patent lumens at the stented segments without hydronephrosis, and the passage of contrast material through it was well preserved. The noncovered stents in the dogs sacrificed at 5 and 10 weeks and one of the two dogs sacrificed at 15 weeks showed near-complete occlusion of the stent lumen due to ingrowth of the soft tissue, and severe hydronephrosis was also noted. The noncovered stent in the other dog sacrificed at 15 weeks showed the passage of contrast material without hydronephrosis, but the lumen of the stent was still nearly occluded by the soft tissue. There was no evidence of hydronephrosis or passage disturbance of the contrast material in both ureters of the dog sacrificed at 30 weeks. We conclude that the newly designed PTFE-covered stent effectively prevented the luminal occlusion caused by urothelial hyperplasia compared to the near-total occlusion of the noncovered stents, and no migration of the covered stents was noted.},
doi = {10.1007/S00270-007-9087-5},
journal = {Cardiovascular and Interventional Radiology},
number = 3,
volume = 31,
place = {United States},
year = 2008,
month = 5
}
  • The purpose of this study was to compare performance of small intestinal submucosa (SIS)-covered endografts (SCEs) to polytetra-fluoroethylene (PTFE)-covered endografts (PCEs) and to bare nitinol stents (BSs) in injured sheep femoral artery (FA). Bare Zilver 6 mm x 40 mm nitinol stents (n = 6), Zilver stents covered with SIS (n = 6), and Palmaz stents 6 mm x 37 mm covered with PTFE (n = 6) were implanted in the balloon-injured FAs of nine female sheep. Follow-up arteriograms were obtained before animal sacrifice at 1, 3 and 6 months, with three animals at each time point. The FAs withmore » the implanted device were explanted for histologic studies and morphologic measurements. Stent implantation was technically successful in all sheep. All BS and SCEs were patent at each time point. Five BSs and five SCEs exhibited formation of progressive eccentric intimal hyperplasia (IH) that was more advanced in SCE at 6 months. Cross-sectional area narrowing averaged 60% for BSs and 67% for SCEs. One BS, one SCE and two patent PCEs exhibited mild-to-moderate formation of concentric IH. Four PCS occluded one at 1 month, two at 3 months and one at 6 months. Performance of the devices placed into sheep FAs depended on their relation to the curving peri-articular portion of the FA during extremity flexion. BSs and SCEs placed in this portion exhibited progressive growth of eccentric IH while PCEs placed in this portion occluded.« less
  • Purpose: To test the vascular wall response to an expanded polytetrafluoroethylene-covered stent, compared with conventional stenting, up to 6 months after deployment in the vascular district of a swine model.Methods: Fourteen minipigs underwent implantation of expanded polytetrafluoroethylene-covered stents (CS) and bare stents (BS) in five peripheral arteries. Animals were killed at different time points (from 1 to 180 days). Histopathologic assessment by morphologic and morphometric analysis and by scanning electron microscopy (SEM) were used to assess the incorporation characteristics and re-endothelialization extent of the two types of stents.Results: A total of 70 stents (14 CS and 14 BS in themore » renal arteries; 28 CS in the iliac arteries, and 14 CS in the aorta) were implanted. Microscopic examination confirmed the absence of occlusive thrombi in both the CS and BS groups. Microthrombi were observed in 10 of 13 CS (77% of cases) and in four of four BS (100% of cases, p < 0.05). Inflammation was mild in 69% of segments in which a CS was implanted and in 74% of segments in which a BS was implanted (p= NS), while a severe inflammatory reaction was observed in 6% of CS segments and in 8% of BS segments (p= NS). No differences were detected at the long-term analysis between neointimal thickness in CS compared with BS segments (0.46 {+-} 0.18 mm vs 0.42 {+-} 0.26 mm at 90 days and 0.36 {+-} 0.08 mm vs 0.35 {+-} 0.04 mm at 180 days; pNS, respectively). At SEM analysis, re-endothelization was evident 15 days after the implant in both CS and BS starting from the stent edges.Conclusion: CS implantation did not elicit a more severe thrombotic deposition compared with that of BS. A similar inflammatory reaction of the arterial wall was present in the two stent groups 3 and 6 months following the implant. In addition, CS implantation did not stimulate excessive neointimal formation when compared with BS.« less
  • No abstract prepared.
  • Four children, three boys and one girl, with a median age of 9 years 8 months, underwent transjugular intrahepatic portosystemic shunt creation with an expanded polytetrafluoroethylene (e-PTFE)-covered nitinol stent. The stent-graft was successfully placed in all four patients without any complication. Clinical and biochemical improvement was noted in all four patients during follow-up. Radiological follow-up with use of duplex ultrasound showed a recurrent stenosis of the shunt 180 days after stent-graft implantation in one patient. This was treated with placement of an additional stent-graft, re-expanding completely the recurrent stenosis. In the other three patients, the stent-graft remained fully patent untilmore » the end of the study or until orthotopic liver transplantation. These preliminary results suggest that use of the Viatorr ePTFE-covered stent-graft in children is safe and feasible, with potentially the same high patency rate and improved clinical outcome as reported in adult patients.« less
  • We assessed, in a prospective study, the efficacy of multidetector spiral computed tomography (MDCT) in the evaluation of transjugular intrahepatic portosystemic shunt (TIPS) patency in patients treated with the Viatorr (Gore, Flagstaff, AZ) expanded-polytetrafluoroethylene (e-PTFE)-covered stent-graft. Eighty patients who underwent TIPS procedure using the Viatorr self-expanding e-PTFE stent-graft were evaluated at follow-up of 1, 3, 6, and 12 months with clinical and laboratory tests as well as ultrasound-color Doppler (USCD) imaging. In case of varices, upper gastrointestinal endoscopy was also performed. In addition, the shunt was evaluated using MDCT at 6 and 12 months. In all cases of abnormal findingsmore » and discrepancy between MDCT and USCD, invasive control venography was performed. MDCT images were acquired before and after injection of intravenous contrast media on the axial plane and after three-dimensional reconstruction using different algorithms. MDCT was successfully performed in all patients. No artefacts correlated to the Viatorr stent-graft were observed. A missing correlation between UCSD and MDCT was noticed in 20 of 80 (25%) patients. Invasive control venography confirmed shunt patency in 16 (80%) cases and shunt malfunction in 4 (20%) cases. According to these data, MDCT sensitivity was 95.2%; specificity was 96.6%; and positive (PPV) and negative predictive values (NPV) were 90.9 and 98.2%, respectively. USCD sensitivity was 90%; specificity was 75%; and PPV and NPV were 54.5 and 95.7%, respectively. A high correlation (K value = 0.85) between MDCT and invasive control venography was observed. On the basis of these results, MDCT shows superior sensitivity and specificity compared with USCD in those patients in whom TIPS was performed with the Viatorr stent-graft. MDCT can be considered a valid tool in the follow-up of these patients.« less