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Janssen P, Tailly T. New Stent Technologies. Urol Clin North Am 2021; 49:185-196. [PMID: 34776051 DOI: 10.1016/j.ucl.2021.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Ureteral stents are an indispensable part of any (endo-) urologic practice. Despite the widely demonstrated advantages of stents, they also carry a considerable risk of side effects and complications, such as urinary symptoms, pain, hematuria, decreased quality of life, stent-related infection, and encrustation. Multiple pathways in preventing or mitigating these side effects and complications and improving stent efficacy have been and are being investigated, including stent architecture and design, biomaterials, and coatings. This article provides an update on currently researched and available stents as well as future perspectives.
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Affiliation(s)
- Pieter Janssen
- Department of Urology, University Hospital Ghent, Corneel Heymanslaan 10, 9000 Ghent, Belgium
| | - Thomas Tailly
- Department of Urology, University Hospital Ghent, Corneel Heymanslaan 10, 9000 Ghent, Belgium.
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Zheng S, Carugo D, Mosayyebi A, Turney B, Burkhard F, Lange D, Obrist D, Waters S, Clavica F. Fluid mechanical modeling of the upper urinary tract. WIREs Mech Dis 2021; 13:e1523. [PMID: 34730288 DOI: 10.1002/wsbm.1523] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Revised: 02/01/2021] [Accepted: 02/02/2021] [Indexed: 12/20/2022]
Abstract
The upper urinary tract (UUT) consists of kidneys and ureters, and is an integral part of the human urogenital system. Yet malfunctioning and complications of the UUT can happen at all stages of life, attributed to reasons such as congenital anomalies, urinary tract infections, urolithiasis and urothelial cancers, all of which require urological interventions and significantly compromise patients' quality of life. Therefore, many models have been developed to address the relevant scientific and clinical challenges of the UUT. Of all approaches, fluid mechanical modeling serves a pivotal role and various methods have been employed to develop physiologically meaningful models. In this article, we provide an overview on the historical evolution of fluid mechanical models of UUT that utilize theoretical, computational, and experimental approaches. Descriptions of the physiological functionality of each component are also given and the mechanical characterizations associated with the UUT are provided. As such, it is our aim to offer a brief summary of the current knowledge of the subject, and provide a comprehensive introduction for engineers, scientists, and clinicians who are interested in the field of fluid mechanical modeling of UUT. This article is categorized under: Cancer > Biomedical Engineering Infectious Diseases > Biomedical Engineering Reproductive System Diseases > Biomedical Engineering.
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Affiliation(s)
- Shaokai Zheng
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Dario Carugo
- Department of Pharmaceutics, UCL School of Pharmacy, University College London, London, UK
| | - Ali Mosayyebi
- Bioengineering Sciences, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
| | - Ben Turney
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, UK
| | - Fiona Burkhard
- Department of Urology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Dirk Lange
- The Stone Centre at Vancouver General Hospital, Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Dominik Obrist
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Sarah Waters
- Oxford Centre for Industrial and Applied Mathematics, Mathematical Institute, University of Oxford, Oxford, UK
| | - Francesco Clavica
- ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
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Sali GM, Joshi HB. Ureteric stents: Overview of current clinical applications and economic implications. Int J Urol 2019; 27:7-15. [PMID: 31549458 DOI: 10.1111/iju.14119] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 09/01/2019] [Indexed: 12/16/2022]
Abstract
Ureteric stents are one of the most crucial tools used for various clinical conditions in the urological field. Placement of a ureteric stent, for short- or long-term use, remains one of the commonest urological interventional procedures. In the past few decades, ureteral stents have undergone notable technological advancements. However, an ideal stent without significant side-effects is yet to be engineered. Indwelling ureteric stents are often accompanied by physical distress to the patient and clinical complications, such as bacterial adhesion, encrustation, malpositioning, stent fracture and forgotten stent syndrome, that influence patients' health-related quality of life. In the market, different stent types are available, designed to reduce infections, and improve patient symptoms and tolerance. In this review, we have emphasized the recent developments that have taken place in stent design, size, materials and coating. This overview looks at current practices and problems related to stents, along with clinical and economic considerations. Few trial studies have been enumerated in the context of utilization of a ureteral stent symptom questionnaire and various stent models to compare their effects in patients.
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Beysens M, Tailly TO. Ureteral stents in urolithiasis. Asian J Urol 2018; 5:274-286. [PMID: 30364608 PMCID: PMC6197553 DOI: 10.1016/j.ajur.2018.07.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 04/29/2018] [Accepted: 05/25/2018] [Indexed: 02/08/2023] Open
Abstract
Ever since the ureteral stent design was fitted with a curl on both sides to prevent it from migrating up or down the ureter some 40 years ago, its use has gained tremendous momentum, aiding in the rise and evolution of endourology and has confidently kept its place in modern time urology. Over the past four decades, several designs, coating and biomaterials have been developed, trying to reduce infection, encrustation and other stent related symptoms. As the ideal stent has not yet been discovered, different ways of helping patients with their complaints have been researched. This review will cover these aspects of stent use in urolithiasis.
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Affiliation(s)
| | - Thomas O. Tailly
- Department of Urology, University Hospital Ghent, Ghent, Belgium
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Kang TW, Chandrasekaran G, Hwang EC, Kim HS, Lakshmanan VK. Characterization and antibacterial activity of PVA–PVP–CS carvacrol-loaded polymer composite films for urinary catheter. INT J POLYM MATER PO 2018. [DOI: 10.1080/00914037.2017.1417286] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Taek Won Kang
- Department of Urology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | | | - Eu Chang Hwang
- Department of Urology, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Hye Su Kim
- Premedical Sciences, Chonnam National University Medical School, Gwangju, Republic of Korea
| | - Vinoth-Kumar Lakshmanan
- Department of Biomedical Sciences, Chonnam National University Medical School, Gwangju, Republic of Korea
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Fluid Structural Analysis of Urine Flow in a Stented Ureter. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:5710798. [PMID: 27127535 PMCID: PMC4830759 DOI: 10.1155/2016/5710798] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/04/2015] [Accepted: 02/29/2016] [Indexed: 11/17/2022]
Abstract
Many urologists are currently studying new designs of ureteral stents to improve the quality of their operations and the subsequent recovery of the patient. In order to help during this design process, many computational models have been developed to simulate the behaviour of different biological tissues and provide a realistic computational environment to evaluate the stents. However, due to the high complexity of the involved tissues, they usually introduce simplifications to make these models less computationally demanding. In this study, the interaction between urine flow and a double-J stented ureter with a simplified geometry has been analysed. The Fluid-Structure Interaction (FSI) of urine and the ureteral wall was studied using three models for the solid domain: Mooney-Rivlin, Yeoh, and Ogden. The ureter was assumed to be quasi-incompressible and isotropic. Data obtained in previous studies from ex vivo and in vivo mechanical characterization of different ureters were used to fit the mentioned models. The results show that the interaction between the stented ureter and urine is negligible. Therefore, we can conclude that this type of models does not need to include the FSI and could be solved quite accurately assuming that the ureter is a rigid body and, thus, using the more simple Computational Fluid Dynamics (CFD) approach.
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Abstract
Ureteral stents are commonly used in urology. Every urologist is familiar with the problems that are associated with stents including infection, encrustation, and bothersome symptoms. These problems limit and affect the use of ureteral stents which are necessary, even in light of the problems they can cause. New designs such as a helically cut ureteral stent which is designed to stretch and conform to the ureter is designed to improve comfort. Drug-eluting designs with an antimicrobial (triclosan) are designed to reduce bacterial adherence to ureteral stents. Chlorhexidine, an antiseptic, has been incorporated into a stent and held in place by a slow release varnish to prevent biofilm formation. Combinations of antibiotics coated directly on the stent and administered systemically have been shown to reduce stent colonization both in vitro and in vivo. Gel-based ureteral stents were also showed to reduce bacterial infection and colonization. Bioabsorbable materials have also been designed to reduce infection, symptoms and prevent the forgotten stent syndrome. Newer designs including stents based on guidewire technology, gels, and a combination of self-expanding wire stents with polymer films are reviewed. There is hope on the horizon that new stents will be able to effectively tackle problems that are often seen with ureteral stents.
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Affiliation(s)
- Hilary Brotherhood
- Department of Urologic Sciences, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
| | - Dirk Lange
- Department of Urologic Sciences, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
| | - Ben H Chew
- Department of Urologic Sciences, University of British Columbia, Vancouver, BC V5Z 1M9, Canada
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Del Junco M, Yoon R, Okhunov Z, Abedi G, Hwang C, Dolan B, Landman J. Comparison of Flow Characteristics of Novel Three-Dimensional Printed Ureteral Stents Versus Standard Ureteral Stents in a Porcine Model. J Endourol 2015. [PMID: 26196704 DOI: 10.1089/end.2014.0716] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
PURPOSE We compared the flow characteristics of novel three-dimensional (3D) printed ureteral stents with four conventional double-pigtail stents in an ex vivo porcine model. MATERIALS AND METHODS In six ex vivo porcine urinary systems with kidneys and ureters intact, we deployed a 5F occlusion catheter in an interpolar calix. We tested each system with antegrade irrigation with a 0.9% saline bag placed 35 cm above the renal pelvis. We evaluated four standard stents (6F Universa® Soft, 7F Percuflex,™ 7/10F Applied Endopyelotomy, 8.5F Filiform Double Pigtail) and compared them with a 9F 3D printed prototype stent. For each stent, we measured the total, extraluminal, and intraluminal flow rates. RESULTS The mean total flow rates for 3D printed stents were significantly higher than the 6F, 7F, and 7/10F stents (P<0.05). No significant difference was seen in the total flow rate for the 3D printed stent and the 8.5F stent. The mean extraluminal flow rates for the 3D stents were similar to those of 7F stents, but significantly lower than 6F stents (P<0.001) and 8.5F stents (P<0.05) and higher than 7/10F stents (P<0.001). The mean intraluminal flow rates for the 3D printed stents were significantly higher than the 6F, 7F, 7/10F, and 8.5F stents (P<0.05). CONCLUSIONS In this pilot study, 3D printed stents manifested a mean total flow rate comparable to the flow rates of contemporary stents. Continued advances in technology and material may permit functionally feasible 3D printed ureteral stents.
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Affiliation(s)
- Michael Del Junco
- 1 Department of Urology, University of California , Irvine, Orange, California
| | - Renai Yoon
- 1 Department of Urology, University of California , Irvine, Orange, California
| | - Zhamshid Okhunov
- 1 Department of Urology, University of California , Irvine, Orange, California
| | - Garen Abedi
- 1 Department of Urology, University of California , Irvine, Orange, California
| | - Christina Hwang
- 1 Department of Urology, University of California , Irvine, Orange, California
| | - Benjamin Dolan
- 2 Department of Engineering, University of California , Irvine, Orange, California
| | - Jaime Landman
- 1 Department of Urology, University of California , Irvine, Orange, California
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