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Khan SA, Rahman ZU, Javed A, Ahmad Z, Cai Z, Jiang O, Xu G. Natural biopolymers in the fabrication and coating of ureteral stent: An overview. BIOMATERIALS ADVANCES 2024; 165:214009. [PMID: 39216319 DOI: 10.1016/j.bioadv.2024.214009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 08/26/2024] [Accepted: 08/27/2024] [Indexed: 09/04/2024]
Abstract
Ureteral stents are indwelling medical devices that are most commonly used in treating different urinary tract complications like ureteral obstruction, kidney stones, and strictures, and allow normal urine flow from the kidney to the bladder. Tremendous work has been done in ureteral stent technology to meet the clinical demands, however, till-date a gold standard material for ureteral stents has not yet been developed. Many materials such as metal, and synthetic polymers have been published, however, the role of natural biopolymers has not yet been summarized and discussed. There is no detailed review published to explain the role of natural biopolymers in ureteral stent technology. This is the first review that explains and summarizes the role of natural polymer in ureter stent technology. In this review alginate and chitosan polymers are discussed in detail in the fabrications and coating of ureteral stents. It was summarized that alginate polymer alone or in combination with other polymers have been successfully used by many researchers for the manufacturing of ureteral stents with satisfactory results in vitro, in vivo, and clinical trials. However, alginate is rarely used to coat the surface of ureteral stent. On the other hand, only two reports are available on chitosan polymers for the manufacturing of ureteral stents, however, chitosan is largely used to coat the existing ureteral stents owing to their good antibacterial characteristics. Coating procedures can inhibit encrustation and biofilm formation. Nevertheless, the lack of antibacterial efficiency and inadequate coating limit their applications, however, natural biopolymers like chitosan showed significant promises in coating. Overall, the renewable nature, abundant, biocompatible, and biodegradable potential of natural polymer can be established with significant aspects as the ideal ureteral stent. To fully utilize the potential of the natural biopolymers in the ureteral stent design or coatings, an in-depth study is required to understand and identify their performance both in vitro and in vivo in the urinary tract.
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Affiliation(s)
- Shahid Ali Khan
- Department of Urology, Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510700, China; Department of Chemistry, School of Natural Sciences, National University of Science and Technology (NUST), Islamabad 44000, Pakistan
| | - Zia Ur Rahman
- Department of Chemistry, University of Swabi, Anbar 23561, Khyber Pakhtunkhwa, Pakistan
| | - Aimen Javed
- Department of Chemistry, School of Natural Sciences, National University of Science and Technology (NUST), Islamabad 44000, Pakistan
| | - Zubair Ahmad
- Department of Chemistry, University of Swabi, Anbar 23561, Khyber Pakhtunkhwa, Pakistan
| | - Zhiduan Cai
- Department of Urology, Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510700, China
| | - Ouyang Jiang
- School of Biomedical Engineering, Guangzhou Medical University, Guangzhou 511436, China
| | - Guibin Xu
- Department of Urology, Key Laboratory of Biological Targeting Diagnosis, Therapy and Rehabilitation of Guangdong Higher Education Institutes, The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou Medical University, Guangzhou 510700, China.
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Zhang Y, Yu CF, Zhang JH, Qiao LD, Yan W, Qin CP. Establishment and Evaluation of Patient-Specific Virtual Ureteroscopy in Assisting Flexible Ureteroscopy for Urolithiasis. Surg Innov 2017; 24:440-445. [PMID: 28494641 DOI: 10.1177/1553350617708075] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objectives. To establish virtual ureteroscopy (VU) through computed tomography urography (CTU) data from patients with upper urinary tract (UUT) stones indicated for flexible ureteroscopy (fURS) and to validate its effectiveness. Methods. Patient-specific VU generation was accomplished through incorporating CTU data into specialized software (Crusher) developed on the open access Visualization Tools Kit (VTK). These were then presented to fURS experts and novice urologists for evaluation and comparison using modified Likert-type questionnaire of 10-point rating scales (1 = not at all useful/not at all realistic/poor, 10 = very useful/very realistic/ excellent). Results. Face and content validation of VU from 5 fURS experts in 3 different centers: overall usefulness 7.4 ± 0.5, graphics 7.4 ± 0.5, intrarenal anatomy 8.4 ± 0.5, stone details 7.8 ± 0.4, usefulness in surgical planning and training 7.6 ± 0.9. Significant increase of detection in the number of calyces and stones was found from using CTU only to CTU-VU combined in the novice group ( P = .000). Before VU observation, novices found much fewer calyces and stones than experts ( P = .004 and .000, respectively). However, this gap disappeared after VU observation ( P = .327 and .292, respectively). VU feedback from the novices was superb. Conclusions. Establishing patient-specific VU through CTU data from renal stone patients is feasible. The present VU can significantly improve novice urologists’ comprehension of intrarenal anatomy and stone information before fURS procedures. Face and content validity is also proved. This novel modality may serve as an important tool for fURS surgical planning, navigation, and training.
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Affiliation(s)
- Yi Zhang
- Peking University International Hospital, Beijing, China
| | - Cheng-fan Yu
- Peking University International Hospital, Beijing, China
| | - Jun-hui Zhang
- Chaoyang Hospital of Capital Medical University, Beijing, China
| | - Lu-dong Qiao
- Tongren Hospital of Capital Medical University, Beijing, China
| | - Wei Yan
- Tongren Hospital of Capital Medical University, Beijing, China
| | - Cai-peng Qin
- Peking University International Hospital, Beijing, China
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Endoscopic Removal of a Nitinol Mesh Stent from the Ureteropelvic Junction after 15 Years. Case Rep Urol 2015; 2015:273614. [PMID: 26697258 PMCID: PMC4678068 DOI: 10.1155/2015/273614] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2015] [Accepted: 11/24/2015] [Indexed: 11/18/2022] Open
Abstract
We report a rare case of a patient with a large stone encrusted on a nitinol mesh stent in the ureteropelvic junction. The stent was inserted in the year 2000 after failure of two pyeloplasty procedures performed due to symptomatic ureteropelvic junction stenosis. By combining minimally invasive urinary stone therapies-extracorporeal shock wave lithotripsy, semirigid ureterorenoscopy with laser lithotripsy, and percutaneous nephrolithotomy-it was possible to completely remove the encrusted stone and nitinol mesh stent that was implanted for 15 years, rendering the patient symptom and obstruction free.
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Liatsikos E, Kallidonis P, Stolzenburg JU, Karnabatidis D. Ureteral stents: past, present and future. Expert Rev Med Devices 2014; 6:313-24. [DOI: 10.1586/erd.09.5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Liatsikos E, Kyriazis I, Kallidonis P, Tsamandas A, Karnabatidis D, Sakellaropoulos G, Flaris N, Kalogeropoulou C, Filos K, Stolzenburg JU, Kardamakis D. Ureteric response to abdominal radiotherapy and metallic double-pigtail ureteric stents: a pig model. BJU Int 2009; 104:862-6. [PMID: 19389017 DOI: 10.1111/j.1464-410x.2009.08507.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE To examine the safety and compatibility of full-length metal ureteric stents with abdominal radiotherapy. MATERIALS AND METHODS Four ureteric stents (Resonance(TM), Cook Urological, Ireland) (RS) and four RSs specially modified to contain thermocouples were placed unilaterally in eight pigs. The contralateral ureters of the same pigs served as their controls, and contained two polymeric ureteric catheters and two similar specially modified to contain thermocouples, while the remaining four control ureters remained intact. All pigs were exposed to abdominal radiotherapy. The dose rate was approximately 5.3 Gy/min and a total radiation dose of 10 Gy was administered. Throughout the treatment the temperature was monitored by the RSs and catheters containing the thermocouples. The pigs were killed at 1 day (four), 7 days (two) and 15 days (two) after treatment, and all ureters examined histologically. RESULTS There was no statistically significant increase in RS and catheter temperature throughout the treatment in any of the treated pigs (P > 0.05). All histological lesions reported were due to radiation treatment. There were no differences in histology between the ureters containing RSs and controls. CONCLUSION RS usage is unrelated to any increase in stent temperature during abdominal radiotherapy and does not cause any further deterioration in the histology of the ipsilateral ureter, additional to that caused by the initial treatment.
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Li X, He Z, Yuan J, Zeng G, He Y, Lei M. Long-term results of permanent metallic stent implantation in the treatment of benign upper urinary tract occlusion. Int J Urol 2007; 14:693-8. [PMID: 17681057 DOI: 10.1111/j.1442-2042.2007.01802.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM The management of complicated benign upper urinary tract occlusion is extremely challenging, especially in patients unable to undergo an open operative procedure. We report the long-term results of a permanent metallic stent for benign upper urinary tract occlusion. METHODS From October 1995 to December 1998, 13 patients (8 men and 5 women, with a mean age of 43 years) with benign upper tract occlusion have been treated by metallic stent implantation. All patients had a nephrostomy tube to relieve the obstruction and the average time of the nephrostomy tube stay was 27 months, ranging from 3 to 131 months. The average length of occlusion was 2.7 cm, ranging from 1 to 3.6 cm. Ultrasonography, urography, diuresis renography and urine culture were performed every 3 months after stent insertion. Ureteroscopy was done when needed. RESULTS The mean follow-up was 92 months (12-132 months). Ureteral patency was achieved in six patients and assisted patency with a Double-J stent was achieved in three patients. In two patients the kidney had to be removed because of progressive malfunction and in two patients the metal stent had to be extracted with the Holmium: YAG laser, burning it down due to the uncontrollable pyonephrosis. In three patients the ipsilateral flank pain recurred. One of these patients experienced urine leakage due to the initial nephrostomy tract: a ureteroscopy revealed a complete hyperplastic urothelial response. Proximal stone formations were found in 2 patients and all were removed by percutaneous nephrolithotomy (PCNL). No stent migration or fragmentation was observed. CONCLUSION The implantation of metal stent is a safe and effective treatment for benign upper urinary tract occlusion, and has satisfying long-term outcome in selected cases. A further investigation is needed for its impact on the urodynamics of upper urinary tract.
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Affiliation(s)
- Xun Li
- Department of Urology, Minimally Invasive Surgery Center, The First Affiliated Hospital of Guangzhou Medical College, Guangzhou, China
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Koletsis EN, Kalogeropoulou C, Prodromaki E, Kagadis GC, Katsanos K, Spiropoulos K, Petsas T, Nikiforidis GC, Dougenis D. Tumoral and non-tumoral trachea stenoses: evaluation with three-dimensional CT and virtual bronchoscopy. J Cardiothorac Surg 2007; 2:18. [PMID: 17430592 PMCID: PMC1950485 DOI: 10.1186/1749-8090-2-18] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2007] [Accepted: 04/12/2007] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND We evaluated the ability of 3D-CT and virtual bronchoscopy to estimate trachea stenosis in comparison to conventional axial CT and fiberoptic bronchoscopy, with a view to assist thoracic surgeons in depicting the anatomical characteristics of tracheal strictures. METHODS Spiral CT was performed in 16 patients with suspected tracheal stenoses and in 5 normal subjects. Tracheal stenoses due to an endoluminal neoplasm were detected in 13 patients, whilst post-intubation tracheal stricture was observed in the other 3 patients. Multiplanar reformatting (MPR), volume rendering techniques (VRT) and virtual endoscopy (VE) for trachea evaluation were applied and findings were compared to axial CT and fiberoptic bronchoscopy. The accuracy of the procedure in describing the localization and degree of stenosis was tested by two radiologists in a blinded controlled trial. RESULTS The imaging modalities tested showed the same stenoses as the ones detected by flexible bronchoscopy and achieved accurate and non-invasive morphological characterization of the strictures, as well as additional information about the extraluminal extent of the disease. No statistically significant difference was observed between the bronchoscopic findings and the results of axial CT estimations (P = 1.0). No statistically significant differences were observed between bronchoscopic findings and the MPR, VRT and VE image evaluations (P = 0.705, 0.414 and 0.414 respectively). CONCLUSION CT and computed generated images may provide a high fidelity, noninvasive and reproducible evaluation of the trachea compared to bronchoscopy. They may play a role in assessment of airway patency distal to high-grade stenoses, and represent a reliable alternative method for patients not amenable to conventional bronchoscopy.
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Affiliation(s)
- Efstratios N Koletsis
- Department of Cardiothoracic Surgery, School of Medicine, University of Patras, Greece
- Department of Medical Physics, School of Medicine, University of Patras, Greece
| | | | - Eleni Prodromaki
- Department of Pneumonology, School of Medicine, University of Patras, Greece
| | - George C Kagadis
- Department of Pneumonology, School of Medicine, University of Patras, Greece
| | | | | | - Theodore Petsas
- Department of Radiology, School of Medicine, University of Patras, Greece
| | | | - Dimitris Dougenis
- Department of Cardiothoracic Surgery, School of Medicine, University of Patras, Greece
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Liatsikos EN, Karnabatidis D, Kagadis GC, Rokkas K, Constantinides C, Christeas N, Flaris N, Voudoukis T, Scopa CD, Perimenis P, Filos KS, Nikiforidis GC, Stolzenburg JU, Siablis D. Application of Paclitaxel-Eluting Metal Mesh Stents within the Pig Ureter: An Experimental Study. Eur Urol 2007; 51:217-23. [PMID: 16814926 DOI: 10.1016/j.eururo.2006.05.054] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2006] [Accepted: 05/31/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVE The purpose of the present study is to compare the standard bare metal stents (BMS) with the Paclitaxel-Drug Eluting Stent (DES) in the ureter of a pig model. MATERIALS AND METHODS We report on an experimental study with ten female pigs weighing between 25 and 30 kg. 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 24 hours 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 24 hours 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.
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Eller RL, Livingston WJ, Morgan CE, Peters GE, Sillers MJ, Magnuson JS, Rosenthal EL. Expandable tracheal stenting for benign disease: worth the complications? Ann Otol Rhinol Laryngol 2006; 115:247-52. [PMID: 16676820 DOI: 10.1177/000348940611500401] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVES To characterize the limitations of self-expandable stents in the management of benign tracheal stenosis, we performed a retrospective review at a tertiary care medical center. METHODS Patients who underwent tracheal stenting were assessed for the cause and severity of tracheal stenosis, comorbidities, stent-related complications, and follow-up airway procedures. RESULTS Sixteen adults (12 women, 4 men; mean age, 47 years) had a total of 26 stents placed for benign disease. Intubation-related stenoses were most frequent (81%). The average follow-up time was 20 months (range, 1 to 40 months). Each stent remained functional for an average of 12.4 months. In the study group, 87% had a complication that required surgical intervention to maintain a patent airway. The most common problem was granulation tissue formation at the ends of the stent causing airway restenosis (81%), and 5 patients (31%) required tracheotomy as a result of restenosis around the stent. Fourteen of the stents (56%) were removed or expelled from the patients. CONCLUSIONS The implantation of self-expandable stents is a minimally invasive method of managing benign tracheal stenosis. Although a small subset of patients may benefit from placement, the majority of patients have complications that require intervention to maintain a patent airway. Thoughtful discretion is critical in selecting patients for this intervention.
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Affiliation(s)
- Robert L Eller
- Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of Alabama School of Medicine, Birmingham, Alabama, USA
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Chew BH, Denstedt JD. Technology insight: Novel ureteral stent materials and designs. ACTA ACUST UNITED AC 2006; 1:44-8. [PMID: 16474466 DOI: 10.1038/ncpuro0014] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Accepted: 09/18/2004] [Indexed: 11/09/2022]
Abstract
Ureteral stents are an important tool for aiding upper urinary tract drainage, but can cause significant patient morbidity. Common problems include stent-induced pain, hematuria, dysuria, infection, and encrustation. From a urologist's perspective, stents must be easy to maneuver in the urinary tract, radiopaque, and affordable. Since the development of the modern day stent in 1978, stents have evolved to include softer biomaterials that are more resistant to encrustation and infection. An ideal biomaterial is one that is not affected by its environment and does not elicit reactive changes in surrounding tissues. To date, the ideal biomaterial or stent does not exist. This review discusses developments that address the issues of infection, biofilm formation, encrustation, and patient comfort. Stent materials including polyurethane, silicone, biodegradable substances and new combination polymers are reviewed, in addition to novel stent coatings such as heparin, hydrogel, and silver nitrate. Ureteral stent technologies currently lag behind vascular stents, particularly drug-eluting stents, but new developments will continue to improve these essential urological tools.
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Affiliation(s)
- Ben H Chew
- University of Western Ontario, London, Ontario, Canada
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Alberti C, Tizzani A. Ureteropelvic Junction Obstruction: Some new Acquisitions about Etiology, Pathophysiology and Diagnostics. Urologia 2003. [DOI: 10.1177/039156030307001-402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The etiopathogenesis of uretero-pelvic junction obstruction (UPJO) has been the subject of many speculations and it remains, in some ways, a debatable matter. Some recently reported thorough research refer to neuro-mediated pathogenetic mechanisms rather than (or together with) myogenic ones.Advances in US, radioisotopic functional imaging, CT and RM contribute to differentiate the obstructive conditions from the non-obstructive ones and to afford today a better assessment of renal functional damage. Particularly, diuretic renography is a non-invasive test for characterization of the renal functional abnormalities resulting from UPJO. Helical CT with angiography is a useful technique for identification of crossing vessels (pyelo-vascular tangle) which can be used for the pre-surgical planning of endopyelotomy. Endoluminal ultrasonography can be used to guide the position of the incision for endopyelotomy (US-guided endopyelotomy).Laboratory examinations are important to determine the overall renal function (serum creatinine, acid-base balance, serum electrolytes, etc.), urinary MCP-1 and NAG (markers of tubular damage), and to rule out urinary tract infections.The management of UPJO (watchful waiting; either open or laparoscopic dismembered pyeloplasty; endoluminal procedures) is greatly influenced by the diagnostic evaluation.The paper aims to outline the advances in both physiopathology and diagnostics of UPJO on the basis of a review of the literature.
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Affiliation(s)
- C. Alberti
- Ia Clinica Urologica dell'Università degli Studi di Torino, Torino
| | - A. Tizzani
- Ia Clinica Urologica dell'Università degli Studi di Torino, Torino
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