Evaluation of Zotarolimus-Eluting Metal Stent in Animal Ureters (original) (raw)
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Metallic stent in the treatment of ureteral obstruction: Experience of single institute
Journal of the Chinese Medical Association, 2011
Background: The ResonanceÒ metallic stent has been reported to be sufficient for the management of malignant extrinsic ureteral obstructions within a 12-month time period. To determine the effectiveness in each specific patient group, we report our experience using the ResonanceÒ stent in the treatment of ureteral obstructions. Methods: We retrospectively reviewed 20 patients (23 stents) who successfully received the ResonanceÒ metallic stents and divided them into a patent group (n ¼ 19) and an obstructive group (n ¼ 4) according to the treatment results. Twenty-one stents were inserted via cystoscopy or ureteroscopy in a retrograde fashion. The remaining two were inserted via percutaneous nephrostomy in an antegrade manner. Follow-up serum creatinine measurements and sonography were performed. The overall ureteral patency rate and the risk of stent failure were evaluated. Results: The overall ureteral patency rate was 82.6% (19/23). Patients with previous radiotherapy had a 50% (4/8) patency rate which was significantly lower than non-radiotherapy patients (100%, 15/15, p ¼ 0.028). Malignant obstructions in those other than radiotherapy patients had a 100% patency rate (5/5). Benign obstructions in those other than radiotherapy patients had a 100% patency rate (10/10). In the radiotherapy patients, the mode of therapy did not dominate the stent outcome. Conclusion: Patients with ureteral obstructions can be treated sufficiently with the ResonanceÒ metallic stent. Patients who had gynecological malignancies and received radiotherapy had a higher failure rate after ResonanceÒ metallic stent insertion.
Metal Stents in the Urinary Tract{A figure is presented}
2007
Introduction: The successful use of metal stents (MSs) in the vascular and biliary systems led several investigators to propose their use in urology. Methods: In the present study, we review the current literature and present the latest developments with the application of MSs in the urinary tract. Results: The application of MSs in the urinary tract has improved clinical outcome in the treatment of urinary tract strictures and is currently thought to be a useful tool in urology practice. Conclusions: Considerable efforts are being made to optimise stent biomaterial, the coating, and, in general, the ureteral stent design. Continuing the research interest seems to be essential for further clinical improvement, aiming to minimise stent-related morbidity.
Metallic stents for malignant and benign ureteric obstruction
BJU International, 2001
To report our experience of using metallic stents to treat ureteric obstruction caused by malignant or benign disease. Nine patients with obstruction in 11 ureters caused by malignant or benign disease (mean age 61 years, range 35-82, mean follow-up 7 months, range 3-11) were treated using metallic stents. A balloon-expandable metallic stent was used in one patient and self-expandable metallic stents in the remaining eight. All stents were inserted via a percutaneous antegrade approach. Of the 11 ureters, nine remained patent with no further manipulation during the follow-up of 3-11 months. An additional stent was placed in continuity with the first in two ureters of two patients at 4 and 5 weeks after the first procedure because of persistent obstruction. After the second intervention, their obstruction was improved. Transient vesico-ureteric reflux occurred in two of three stented distal ureters, but the reflux resolved spontaneously within 2 months after stent implantation. Ureteric patency was maintained in all patients and no major complications related to stenting occurred during the follow-up. Two patients died from cervical cancer at 3 and 5 months after stenting. In patients with difficult ureteric obstructions a metallic stent provides a safe and effective alternative to an indwelling double-pigtail catheter or percutaneous nephrostomy.
Metallic ureteric stents: early experience
BJU International, 1998
Objective To report our experience with metallic self-quality of life was improved and symptoms such as loin pain were ameliorated. Renal function was pre-expanding stents in the palliative care of patients with ureteric obstruction caused by advanced pelvic served; the mean serum creatinine level before and after stenting was 636 and 263 mmol/L, respectively). malignancy.
Ureteral Metal Stents: 10-Year Experience With Malignant Ureteral Obstruction Treatment
The Journal of Urology, 2009
Purpose: Ureteral patency in malignant ureteral obstruction cases is a therapeutic challenge. We report our long-term experience with palliative treatment for extrinsic malignant ureteral obstruction with percutaneous placement of metal mesh stents. Materials and Methods: From January 1996 to December 2005, 90 patients with a mean age of 59 years (range 35 to 80) with ureteral obstruction due to extrinsic ureteral compression and/or encasement by primary or metastatic tumors, or retroperitoneal lymphadenopathy underwent implantation of self-expandable metal mesh stents. A total of 119 ureters were managed. Followup included urinalysis, blood biochemistry tests and transabdominal ultrasound or intravenous urography. Results: The technical success rate of percutaneous antegrade insertion of ureteral self-expandable metal mesh stents was 100%. Renal biochemistry normalized and hydronephrosis gradually resolved 1 to 2 weeks after stent insertion. Median followup was 15 months (range 8 to 38). Hyperplastic reaction and/or encrustation, or tumor ingrowth developed in 45 stents. Secondary intervention, such as repeat balloon dilation and coaxial stenting, was done to improve patency. Migration was observed in 13 metal stents. The primary and secondary patency rates during followup were 51.2% and 62.1%, respectively. A double pigtail or external-internal stent was inserted in 45 cases in which secondary interventions did not ensure patency. Conclusions: Internal drainage of extrinsic malignant ureteral obstruction with metal mesh stents provides long-term decompression of the upper urinary tract in select cases. Certain problems limit the application of metal mesh stents in the ureter. Further studies are warranted to identify independent predictors of ureteral patency after the application of metal stents for malignant obstruction.
The Journal of Urology, 2011
We assessed the therapeutic value of a new treatment option for ureteral strictures that may avoid urothelial hyperplasia, which is the main cause of metallic stent failure. Materials and Methods: We used 24 pigs in this study. An experimental model of ureteral stricture was induced in all animals. Obstruction was confirmed by ultrasound and retrograde ureteropyelogram 6 weeks after model creation. The pigs were then randomly allocated to 2 experimental groups. Therapy involved placement of a 6 ϫ 30 mm metallic ureteral covered stent in the ureteral stricture in group 1 and subsequent endoureterotomy at the ureteral segments adjacent to the 2 ends of the stent in group 2. A double pigtail stent was then deployed for 3 weeks. Completion studies 6 months after therapy included retrograde ureteropyelogram, endoluminal ultrasound and ureteroscopy to assess urothelial hyperplasia formation. Results: At the end of the study evidence of urothelial hyperplasia was seen in 50% of the pigs in group 1 and in 29% in group 2. Four and 2 cases of cranial stent migration in groups 1 and 2, respectively, were seen at 6 months. Hyperplasia and renal involvement were statistically significantly different between the groups with more damage in group 1 than in group 2. Conclusions: Hyperplasia was markedly reduced when ureteral peristalsis was inhibited by endoureterotomy at the area of interaction between the stent and the ureter.
Journal of Vascular and Interventional Radiology, 2005
PURPOSE: To determine if the deployment of metallic ureteral stents in benign ureteral stricture is more effective than endoureterotomy. MATERIALS AND METHODS: Twenty pigs were randomly divided in two groups to be treated with endoureterotomy or metallic stents. The internal ureteral diameter 2 cm distal to the ureteropelvic junction, histopathologic changes, ultrasonographic and fluoroscopic studies, urine culture, and serum urea and creatinine levels were analyzed during the phases of the study. The study was divided into three phases. The first included premodel documentation of normal urinary tract and laparoscopic ureteral stricture induction. In the second phase 1 month later, diagnosis and endoureteral treatment were carried out. Twelve weeks after stricture treatment, follow-up imaging studies and postmortem evaluation of all animals were performed. RESULTS: The success rates were 80% for endoureterotomy and 70% for metallic stent implantation. In all animals in the latter group, a ureteral hyperplasic reaction took place that affected the zone of stent implantation. One difference between the groups was the presence of urinary infection in 30% of animals in the endoureterotomy group and in no animals treated with metallic stents. Statistically significant differences in ureteral diameter between the first and second study phases were found within both groups (P < .0001), but not between groups (P ؍ .021). Results from pathologic analysis revealed statistically significant differences between groups (P ؍ .0029). CONCLUSIONS: The interaction among the distal end of the metallic stent, the urothelium, and peristalsis might be the origin of the failure of these devices. Although the deployment of metallic stents is attractive compared with other endourologic techniques like endoureterotomy in cases of benign strictures, certain problems must be resolved to prevent hyperplasia. Until then, this technique will not be a fully reliable therapeutic option for ureteral disorders.