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McCormack B, Hampton HL, Speich JE, Radley SC, Burkett LS, Klausner AP. Ultrasound Urodynamics: A Review of Ultrasound Imaging Techniques for Enhanced Bladder Functional Diagnostics. CURRENT BLADDER DYSFUNCTION REPORTS 2024; 19:263-271. [PMID: 39185020 PMCID: PMC11343893 DOI: 10.1007/s11884-024-00758-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/10/2024] [Indexed: 08/27/2024]
Abstract
Purpose of Review Invasive urodynamics are currently used to diagnose disorders of bladder function. However, due to patient discomfort as well as artifacts induced by catheters and non-physiologic filling, less invasive screening tools that can improve diagnostic information, such as ultrasound are required. The purpose of this review is to assess different modalities of ultrasound as applied to functional bladder imaging. This information will help guide future studies in the use of ultrasound during urodynamics. Recent Findings Recently, multiple studies have employed ultrasound to evaluate bladder volume, wall thickness, shape, vibrometry, elastography, compliance, biomechanics, and micromotion during urodynamics. These new techniques have used both 2D and 3D ultrasound techniques to evaluate bladder changes during filling. Continued research is needed to confirm ongoing findings prior to widespread incorporation into clinical practice. Summary This review demonstrates the potential use of ultrasound as an adjunct to urodynamics for the diagnostic evaluation of functional bladder disorders.
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Affiliation(s)
- Brendan McCormack
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA USA
| | - Hailey L. Hampton
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA USA
| | - John E. Speich
- Department of Mechanical & Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA USA
| | - Stephen C. Radley
- Department of Urogynaecology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Linda S. Burkett
- Department of Obstetrics and Gynecology, Virginia Commonwealth University School of Medicine, Richmond, VA USA
| | - Adam P. Klausner
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA USA
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Hennig G, Saxena P, Broemer E, Herrera GM, Roccabianca S, Tykocki NR. Quantifying whole bladder biomechanics using the novel pentaplanar reflected image macroscopy system. Biomech Model Mechanobiol 2023; 22:1685-1695. [PMID: 37249760 PMCID: PMC10511590 DOI: 10.1007/s10237-023-01727-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 05/10/2023] [Indexed: 05/31/2023]
Abstract
Optimal bladder compliance is essential to urinary bladder storage and voiding functions. Calculated as the change in filling volume per change in pressure, bladder compliance is used clinically to characterize changes in bladder wall biomechanical properties that associate with lower urinary tract dysfunction. But because this method calculates compliance without regard to wall structure or wall volume, it gives little insight into the mechanical properties of the bladder wall during filling. Thus, we developed Pentaplanar Reflected Image Macroscopy (PRIM): a novel ex vivo imaging method to accurately calculate bladder wall stress and stretch in real time during bladder filling. The PRIM system simultaneously records intravesical pressure, infused volume, and an image of the bladder in five distinct visual planes. Wall thickness and volume were then measured and used to calculate stress and stretch during filling. As predicted, wall stress was nonlinear; only when intravesical pressure exceeded ~ 15 mmHg did bladder wall stress rapidly increase with respect to stretch. This method of calculating compliance as stress vs stretch also showed that the mechanical properties of the bladder wall remain similar in bladders of varying capacity. This study demonstrates how wall tension, stress and stretch can be measured, quantified, and used to accurately define bladder wall biomechanics in terms of actual material properties and not pressure/volume changes. This method is especially useful for determining how changes in bladder biomechanics are altered in pathologies where profound bladder wall remodeling occurs, such as diabetes and spinal cord injury.
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Affiliation(s)
- Grant Hennig
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Pragya Saxena
- Department of Pharmacology and Toxicology, Michigan State University College of Osteopathic Medicine, East Lansing, MI, 48824, USA
| | - Eli Broemer
- Department of Mechanical Engineering, Michigan State University College of Engineering, East Lansing, MI, 48824, USA
| | - Gerald M Herrera
- Department of Pharmacology, University of Vermont Larner College of Medicine, Burlington, VT, 05405, USA
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University College of Engineering, East Lansing, MI, 48824, USA
| | - Nathan R Tykocki
- Department of Pharmacology and Toxicology, Michigan State University College of Osteopathic Medicine, East Lansing, MI, 48824, USA.
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Tuttle T, McClintock D, Roccabianca S. Effects of swelling and anatomical location on the viscoelastic behavior of the porcine urinary bladder wall. J Mech Behav Biomed Mater 2023; 143:105926. [PMID: 37269604 DOI: 10.1016/j.jmbbm.2023.105926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 05/18/2023] [Accepted: 05/21/2023] [Indexed: 06/05/2023]
Abstract
The ability of the urinary bladder to perform its physiological function depends largely on its mechanical characteristics. Understanding the mechanics of this tissue is crucial to the development of accurate models of not just this specific organ, but of the pelvic floor overall. In this study, we tested porcine bladder to identify variations in the tissue's viscoelastic characteristics associated with anatomical locations and swelling. We investigated this relationship using a series of stress-relaxation experiments as well as a modified Maxwell-Wiechert model to aid in the interpretation of the experimental data. Our results highlight that tissue located near the neck of the bladder presents significantly different viscoelastic characteristics than the body of the organ. This supports what was previously observed and is a valuable contribution to the understanding of the location-specific properties of the bladder. We also tested the effect of swelling, revealing that the bladder's viscoelastic behavior is mostly independent of solution osmolarity in hypoosmotic solutions, but the use of a hyperosmotic solution can significantly affect its behavior. This is significant, since several urinary tract pathologies can lead to chronic inflammation and disrupt the urothelial barrier causing increased urothelial permeability, thus subjecting the bladder wall to non-physiologic osmotic challenge.
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Affiliation(s)
- Tyler Tuttle
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, 48823, USA
| | - Dillon McClintock
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, 48823, USA
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, 48823, USA.
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Saxena P, Broemer E, Herrera GM, Mingin GC, Roccabianca S, Tykocki NR. Compound 48/80 increases murine bladder wall compliance independent of mast cells. Sci Rep 2023; 13:625. [PMID: 36635439 PMCID: PMC9837046 DOI: 10.1038/s41598-023-27897-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Accepted: 01/10/2023] [Indexed: 01/13/2023] Open
Abstract
A balance between stiffness and compliance is essential to normal bladder function, and changes in the mechanical properties of the bladder wall occur in many bladder pathologies. These changes are often associated with the release of basic secretagogues that in turn drive the release of inflammatory mediators from mast cells. Mast cell degranulation by basic secretagogues is thought to occur by activating an orphan receptor, Mas-related G protein-coupled receptor B2 (Mrgprb2). We explored the effects of the putative mast cell degranulator and Mrgprb2 agonist Compound 48/80 on urinary bladder wall mechanical compliance, smooth muscle contractility, and urodynamics, and if these effects were mast cell dependent. In wild-type mice, Mrgprb2 receptor mRNA was expressed in both the urothelium and smooth muscle layers. Intravesical instillation of Compound 48/80 decreased intermicturition interval and void volume, indicative of bladder overactivity. Compound 48/80 also increased bladder compliance while simultaneously increasing the amplitude and leading slope of transient pressure events during ex vivo filling and these effects were inhibited by the Mrgprb2 antagonist QWF. Surprisingly, all effects of Compound 48/80 persisted in mast cell-deficient mice, suggesting these effects were independent of mast cells. These findings suggest that Compound 48/80 degrades extracellular matrix and increases urinary bladder smooth muscle excitability through activation of Mrgprb2 receptors located outside of mast cells. Thus, the pharmacology and physiology of Mrgprb2 in the urinary bladder is of potential interest and importance in terms of treating lower urinary tract dysfunction.
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Affiliation(s)
- Pragya Saxena
- Department of Pharmacology and Toxicology, Michigan State University College of Osteopathic Medicine, East Lansing, MI, USA
| | - Eli Broemer
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, USA
| | - Gerald M Herrera
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Gerald C Mingin
- Division of Urology, University of Vermont Larner College of Medicine, Burlington, VT, USA
| | - Sara Roccabianca
- Department of Mechanical Engineering, Michigan State University, East Lansing, MI, USA
| | - Nathan R Tykocki
- Department of Pharmacology and Toxicology, Michigan State University College of Osteopathic Medicine, East Lansing, MI, USA.
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Jaskowak D, Nunez R, Ramachandran R, Alhajjar E, Yin J, Guidoboni G, Danziger ZC. Mathematical modeling of the lower urinary tract: A review. Neurourol Urodyn 2022; 41:1305-1315. [PMID: 35753055 PMCID: PMC9891477 DOI: 10.1002/nau.24995] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 05/31/2022] [Accepted: 06/09/2022] [Indexed: 02/03/2023]
Abstract
AIMS Understand what progress has been made toward a functionally predictive lower urinary tract (LUT) model, identify knowledge gaps, and develop from them a path forward. METHODS We surveyed prominent mathematical models of the basic LUT components (bladder, urethra, and their neural control) and categorized the common modeling strategies and theoretical assumptions associated with each component. Given that LUT function emerges from the interaction of these components, we emphasized attempts to model their connections, and highlighted unmodeled aspects of LUT function. RESULTS There is currently no satisfactory model of the LUT in its entirety that can predict its function in response to disease, treatment, or other perturbations. In particular, there is a lack of physiologically based mathematical descriptions of the neural control of the LUT. CONCLUSIONS Based on our survey of the work to date, a potential path to a predictive LUT model is a modular effort in which models are initially built of individual tissue-level components using methods that are extensible and interoperable, allowing them to be connected and tested in a common framework. A modular approach will allow the larger goal of a comprehensive LUT model to be in sight while keeping individual efforts manageable, ensure new models can straightforwardly build on prior research, respect potential interactions between components, and incentivize efforts to model absent components. Using a modular framework and developing models based on physiological principles, to create a functionally predictive model is a challenge that the field is ready to undertake.
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Affiliation(s)
- Daniel Jaskowak
- Department of Biomedical Engineering, Florida International University, Miami, Florida, USA
| | - Roberto Nunez
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, Missouri, USA
| | - Rahul Ramachandran
- Department of Chemical and Biological Engineering, Wisconsin Institute for Discovery, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Elie Alhajjar
- Department of Mathematical Sciences, United States Military Academy, New York, New York, USA
| | - John Yin
- Department of Chemical and Biological Engineering, Wisconsin Institute for Discovery, University of Wisconsin–Madison, Madison, Wisconsin, USA
| | - Giovanna Guidoboni
- Department of Electrical Engineering and Computer Science, University of Missouri, Columbia, Missouri, USA
- Department of Mathematics, University of Missouri, Columbia, Missouri, USA
| | - Zachary C. Danziger
- Department of Biomedical Engineering, Florida International University, Miami, Florida, USA
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Maddra KM, Li R, Nagle AS, Klausner AP, Speich JE. Repeatability of Ultrasound-Defined Bladder Shape Metrics in Healthy Volunteers. Res Rep Urol 2022; 14:185-192. [PMID: 35572816 PMCID: PMC9091689 DOI: 10.2147/rru.s351347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Accepted: 04/16/2022] [Indexed: 11/23/2022] Open
Abstract
Purpose Patients and Methods Results Conclusion
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Affiliation(s)
- Kaitlyn M Maddra
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Rui Li
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USA
| | - Anna S Nagle
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USA
| | - Adam P Klausner
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USA
- Correspondence: John E Speich, Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, VA, USA, Tel +1 804 827 7036, Fax +1 804 827 7030, Email
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Rosen DP, Larson NB, Alizad A, Fatemi M. Non-invasive measurement of the internal pressure of a pressurized biological compartment using Lamb waves. IEEE Trans Biomed Eng 2021; 69:1860-1869. [PMID: 34807817 DOI: 10.1109/tbme.2021.3129652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
In this study, we propose a mechanical analysis for estimating the internal pressure of a finitely deformed spherical compartment from Lamb wave measurements. The proposed analysis produces a dispersion relation associating Lamb wave speed with pressure using limited material parameters (only a strain stiffening term). The analysis was validated on ultrasound bladder vibrometry (UBV) experiments collected from 9 ex vivo porcine bladders before and after formalin cross-linking. Estimated pressures were compared with pressures measured directly by a pressure transducer. The proposed analysis proved broadly effective at estimating pressure from UBV based Lamb wave without calibration as demonstrated by the observed concordance between estimated and measured pressures (Lins CCC = 0.82 (0.66-0.91). Theoretical limitations and potential refinements to improve the accuracy and generality of the approach are discussed.
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8
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A Data-Driven Memory-Dependent Modeling Framework for Anomalous Rheology: Application to Urinary Bladder Tissue. FRACTAL AND FRACTIONAL 2021. [DOI: 10.3390/fractalfract5040223] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We introduce a data-driven fractional modeling framework for complex materials, and particularly bio-tissues. From multi-step relaxation experiments of distinct anatomical locations of porcine urinary bladder, we identify an anomalous relaxation character, with two power-law-like behaviors for short/long long times, and nonlinearity for strains greater than 25%. The first component of our framework is an existence study, to determine admissible fractional viscoelastic models that qualitatively describe linear relaxation. After the linear viscoelastic model is selected, the second stage adds large-strain effects to the framework through a fractional quasi-linear viscoelastic approach for the nonlinear elastic response of the bio-tissue of interest. From single-step relaxation data of the urinary bladder, a fractional Maxwell model captures both short/long-term behaviors with two fractional orders, being the most suitable model for small strains at the first stage. For the second stage, multi-step relaxation data under large strains were employed to calibrate a four-parameter fractional quasi-linear viscoelastic model, that combines a Scott-Blair relaxation function and an exponential instantaneous stress response, to describe the elastin/collagen phases of bladder rheology. Our obtained results demonstrate that the employed fractional quasi-linear model, with a single fractional order in the range α = 0.25–0.30, is suitable for the porcine urinary bladder, producing errors below 2% without need for recalibration over subsequent applied strains. We conclude that fractional models are attractive tools to capture the bladder tissue behavior under small-to-large strains and multiple time scales, therefore being potential alternatives to describe multiple stages of bladder functionality.
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9
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Salem SA, Rashidbenam Z, Jasman MH, Ho CCK, Sagap I, Singh R, Yusof MR, Md Zainuddin Z, Haji Idrus RB, Ng MH. Incorporation of Smooth Muscle Cells Derived from Human Adipose Stem Cells on Poly(Lactic-co-Glycolic Acid) Scaffold for the Reconstruction of Subtotally Resected Urinary Bladder in Athymic Rats. Tissue Eng Regen Med 2020; 17:553-563. [PMID: 32583275 DOI: 10.1007/s13770-020-00271-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 04/12/2020] [Accepted: 05/06/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The urinary tract can be affected by both congenital abnormalities as well as acquired disorders, such as cancer, trauma, infection, inflammation, and iatrogenic injuries, all of which may lead to organ damage requiring eventual reconstruction. As a gold standard, gastrointestinal segment is used for urinary bladder reconstruction. However, one major problem is that while bladder tissue prevents reabsorption of specific solutes, gastrointestinal tissue actually absorbs them. Therefore, tissue engineering approach had been attempted to provide an alternative tissue graft for urinary bladder reconstruction. METHODS Human adipose-derived stem cells isolated from fat tissues were differentiated into smooth muscle cells and then seeded onto a triple-layered PLGA sheet to form a bladder construct. Adult athymic rats underwent subtotal urinary bladder resection and were divided into three treatment groups (n = 3): Group 1 ("sham") underwent anastomosis of the remaining basal region, Group 2 underwent reconstruction with the cell-free scaffold, and Group 3 underwent reconstruction with the tissue-engineered bladder construct. Animals were monitored on a daily basis and euthanisation was performed whenever a decline in animal health was detected. RESULTS All animals in Groups 1, 2 and 3 survived for at least 7 days and were followed up to a maximum of 12 weeks post-operation. It was found that by Day 14, substantial ingrowth of smooth muscle and urothelial cells had occurred in Group 2 and 3. In the long-term follow up of group 3 (tissue-engineered bladder construct group), it was found that the urinary bladder wall was completely regenerated and bladder function was fully restored. Urodynamic and radiological evaluations of the reconstructed bladder showed a return to normal bladder volume and function.Histological analysis revealed the presence of three muscular layers and a urothelium similar to that of a normal bladder. Immunohistochemical staining using human-specific myocyte markers (myosin heavy chain and smoothelin) confirmed the incorporation of the seeded cells in the newly regenerated muscular layers. CONCLUSION Implantation of PLGA construct seeded with smooth muscle cells derived from human adipose stem cells can lead to regeneration of the muscular layers and urothelial ingrowth, leading to formation of a completely functional urinary bladder.
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Affiliation(s)
- Salah Abood Salem
- Urology Unit, Department of Surgery, UKM Medical Centre, Kuala Lumpur, Malaysia.,Tissue Engineering Centre, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, 56000, Kuala Lumpur, Malaysia
| | - Zahra Rashidbenam
- Tissue Engineering Centre, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, 56000, Kuala Lumpur, Malaysia
| | | | | | - Ismail Sagap
- Urology Unit, Department of Surgery, UKM Medical Centre, Kuala Lumpur, Malaysia
| | - Rajesh Singh
- Department of Orthopaedics and Traumatology, UKM Medical Centre, Kuala Lumpur, Malaysia
| | - Mohd Reusmaazran Yusof
- Material Technology Group, Malaysian Nuclear Agency, Kajang, Selangor Darul Ehsan, Malaysia
| | | | - Ruszymah Bt Haji Idrus
- Tissue Engineering Centre, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, 56000, Kuala Lumpur, Malaysia.,Department of Physiology, UKM Medical Faculty, Kuala Lumpur, Malaysia
| | - Min Hwei Ng
- Tissue Engineering Centre, Universiti Kebangsaan Malaysia Medical Centre, Jalan Yaacob Latif, 56000, Kuala Lumpur, Malaysia.
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Gray T, Phillips L, Li W, Buchanan C, Campbell P, Farkas A, Abdi S, Radley S. Evaluation of bladder shape using transabdominal ultrasound: Feasibility of a novel approach for the detection of involuntary detrusor contractions. ULTRASOUND : JOURNAL OF THE BRITISH MEDICAL ULTRASOUND SOCIETY 2020; 27:167-175. [PMID: 32549896 DOI: 10.1177/1742271x19834062] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 02/03/2019] [Indexed: 11/17/2022]
Abstract
Conventional assessment of overactive bladder syndrome uses invasive pressure-measuring catheters to detect bladder contractions (urodynamics). We hypothesised that bladder shape changes detected and measured using transabdominal ultrasound scan could provide a non-invasive and clinically useful alternative investigation of bladder contractions. This feasibility study evaluated a novel transabdominal ultrasound scan bladder shape test during conventional urodynamics and physiological bladder filling. The aim was to initially evaluate and refine a non-invasive approach for detecting and quantifying bladder shape changes associated with involuntary bladder contractions. To develop measurement techniques and characterise bladder shape changes during bladder filling, healthy female volunteers (n=20) and women with overactive bladder symptoms who had previously undergone urodynamics (n=30) completed symptom questionnaires and bladder diaries. The bladder shape test protocol included consumption of 1 l water before undergoing serial transabdominal ultrasound scan imaging of the bladder during physiological bladder filling and during episodes of urgency. In a further group of women with overactive bladder (n=22), serial transabdominal ultrasound scan images were captured during urodynamics so that shape changes occurring with bladder contractions could be characterised. In both healthy volunteers and women with overactive bladder, the transverse view of the bladder provided the most reliable plane to characterise and measure bladder shape changes. A sphericity index derived from the ratio between maximum inscribed and minimum circumscribed ellipses (πac2(inner)/πac2(outer)) offered a reliable and reproducible measurement system. Of participants undergoing transabdominal ultrasound scan during urodynamics, there were significant measurable differences in sphericity index between patients with bladder contractions (n=12) and patients with acontractile bladders (p < 0.001). Bladder shape changes detected during physiological filling and urodynamics have provided preliminary evidence to support further research into bladder shape test as a non-invasive diagnostic tool to identify involuntary bladder contractions in patients with overactive bladder syndrome.
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Affiliation(s)
- Thomas Gray
- Department of Urogynaecology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | | | - Weiguang Li
- University of Sheffield Medical School, Sheffield, UK
| | - Charlotte Buchanan
- Department of Urogynaecology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | | | - Andrew Farkas
- Department of Urogynaecology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Shahram Abdi
- Department of Radiology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
| | - Stephen Radley
- Department of Urogynaecology, Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
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11
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A computational analysis of the effect of supporting organs on predicted vesical pressure in stress urinary incontinence. Med Biol Eng Comput 2020; 58:1079-1089. [PMID: 32152891 DOI: 10.1007/s11517-020-02148-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 02/19/2020] [Indexed: 10/24/2022]
Abstract
Stress urinary incontinence (SUI) or urine leakage from urethra occurs due to an increase in abdominal pressure resulting from stress like a cough or jumping height. SUI is more frequent among post-menopausal women. In the absence of bladder contraction, vesical pressure exceeds urethral pressure leading to urine leakage. The main aim of this study is to utilize fluid-structure interaction techniques to model bladder and urethra computationally under an external pressure like sneezing. Both models have been developed with linear elastic properties for the bladder wall while the patient model has also been simulated utilizing the Mooney-Rivlin solid model. The results show a good agreement between the clinical data and the predicted values of the computational models, specifically the pressure at the center of the bladder. There is 1.3% difference between the predicted vesical pressure and the vesical pressure obtained from urodynamic tests. It can be concluded that the accuracy of the predicted pressure in the center of the bladder is significantly higher for the simulation assuming nonlinear material property (hyperelastic) for the bladder in comparison to the accuracy of the linear elastic model. The model is beneficial for exploring treatment solutions for SUI disorder. Graphical abstract 3D processing of bladder deformation during abdominal pressure of a the physiological model and b the pathological model (starting from left to right and up to down, consecutively).
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12
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Sheen D, Kolli H, Nagle AS, Cullingsworth Z, Vinod NN, Naimi HA, De Wachter SG, Mazzeo SE, Stothers L, Speich JE, Klausner AP. Validation of a real-time bladder sensation meter during oral hydration in healthy adults: Repeatability and effects of fill rate and ultrasound probe pressure. Low Urin Tract Symptoms 2019; 11:224-231. [PMID: 31298501 DOI: 10.1111/luts.12275] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 06/06/2019] [Accepted: 06/17/2019] [Indexed: 11/26/2022]
Abstract
OBJECTIVES A non-invasive protocol was previously developed using three-dimensional ultrasound and a sensation meter to characterize real-time bladder sensation. This study the protocol by measuring the effects of fill rateand ultrasound probe pressure during oral hydration. METHODS Healthy volunteers with no urinary symptoms (based on International Consultation on Incontinence Questionnaire on Overactive Bladder surveys) were recruited into an oral hydration study. Throughout two complete fill-void cycles, participants drank 2 L Gatorade G2 (The Gatorade Company, Inc., Chicago, Illinois) and used a touch-screen sensation meter to record real-time bladder sensation (0%-100%). The study was repeated three times, once per week (Visits A, B, and C). In Visits A and B, ultrasound was used to measure bladder volume every 5 minutes. Ultrasound was not used in Visit C except at 100% capacity. Volume data from Visit B were used to estimate volumes throughout the fills in Visit C. Sensation-capacity curves were generated for each fill for comparative analysis. RESULTS Ten participants completed three visits (60 total fills). Increased fill rate led to decreased sensation throughout filling, andultrasound probe pressure led to increased sensation. Participants reported higher sensation at low volumes during Fill 1 of Visit A before training with the sensation meter. Sensation curves with intermittent ultrasound showed repeatability for Fill 2 in Visits A and B. Fill rate and ultrasound probe pressure affect real-time bladder sensation during oral hydration. CONCLUSIONS This study demonstrated repeatability of real-time bladder sensation during a two-fill oral hydration protocol with ultrasound.
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Affiliation(s)
- Derek Sheen
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Hiren Kolli
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Anna S Nagle
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, Virginia
| | - Zachary Cullingsworth
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, Virginia
| | - Naomi N Vinod
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Hameeda A Naimi
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Stefan G De Wachter
- Department of Urology, University Hospital Antwerpen, Edegem, Belgium.,Department of Urology, University of Antwerpen, Wilrijk, Belgium
| | - Suzanne E Mazzeo
- Department of Psychology, Virginia Commonwealth University, College of Humanities and Sciences, Richmond, Virginia
| | - Lynn Stothers
- Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - John E Speich
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University College of Engineering, Richmond, Virginia
| | - Adam P Klausner
- Department of Surgery/Division of Urology, Virginia Commonwealth University School of Medicine, Richmond, Virginia
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13
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De Pascalis R, Parnell WJ, Abrahams ID, Shearer T, Daly DM, Grundy D. The inflation of viscoelastic balloons and hollow viscera. Proc Math Phys Eng Sci 2018; 474:20180102. [PMCID: PMC6237490 DOI: 10.1098/rspa.2018.0102] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 09/19/2018] [Indexed: 10/13/2023] Open
Abstract
For the first time, the problem of the inflation of a nonlinear viscoelastic thick-walled spherical shell is considered. Specifically, the wall has quasilinear viscoelastic constitutive behaviour, which is of fundamental importance in a wide range of applications, particularly in the context of biological systems such as hollow viscera, including the lungs and bladder. Experiments are performed to demonstrate the efficacy of the model in fitting relaxation tests associated with the volumetric inflation of murine bladders . While the associated nonlinear elastic problem of inflation of a balloon has been studied extensively, there is a paucity of studies considering the equivalent nonlinear viscoelastic case. We show that, in contrast to the elastic scenario, the peak pressure associated with the inflation of a neo-Hookean balloon is not independent of the shear modulus of the medium. Moreover, a novel numerical technique is described in order to solve the nonlinear Volterra integral equation in space and time originating from the fundamental problem of inflation and deflation of a thick-walled nonlinear viscoelastic shell under imposed pressure.
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Affiliation(s)
- Riccardo De Pascalis
- Dipartimento di Matematica e Fisica ‘E. De Giorgi’, Università del Salento, Via per Arnesano, 73100 Lecce, Italy
- School of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - William J. Parnell
- School of Mathematics, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - I. David Abrahams
- Isaac Newton Institute, University of Cambridge, 20 Clarkson Road, Cambridge CB3 0EH, UK
| | - Tom Shearer
- School of Materials, University of Manchester, Oxford Road, Manchester M13 9PL, UK
| | - Donna M. Daly
- School of Pharmacy and Biomedical Science, University of Central Lancashire, Preston PR1 2HE, UK
| | - David Grundy
- Department of Biomedical Science, University of Sheffield, Sheffield S10 2TN, UK
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Use of Ultrasound Urodynamics to Identify Differences in Bladder Shape Between Individuals With and Without Overactive Bladder. Female Pelvic Med Reconstr Surg 2018; 26:635-639. [PMID: 30256268 DOI: 10.1097/spv.0000000000000638] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
OBJECTIVES The objective of this study was to identify differences in bladder shape changes between individuals with overactive bladder (OAB) and unaffected individuals during ultrasound urodynamics. METHODS A prospective urodynamic study was performed with concurrent transabdominal ultrasound (ultrasound urodynamics) on individuals with and without OAB based on validated International Consultation on Incontinence Questionnaire - OAB survey scores. Three-dimensional ultrasound images were acquired at 1-minute increments during filling and used to measure bladder diameters in the height, width, and depth orientations. The engineering strain for each diameter was compared between participants with OAB and controls during urodynamic filling. The height-to-width ratio at capacity was used to determine if individuals were shape outliers. RESULTS A total of 22 subjects were enrolled, including 11 with OAB and 11 without OAB. During urodynamic filling in both groups, the greatest degree of geometric strain was found in the height orientation, indicating that bladders generally fill in a craniocaudal shape. The mean ± SD height-to-width ratio of the control group was 1.06 ± 0.12 yielding a 95% confidence interval of 0.82 to 1.30. Five (45.5%) of 11 OAB subjects had height-to-width ratios outside this interval as compared with none of the control subjects, identifying a potential shape-mediated subgroup of OAB. CONCLUSIONS Three-dimensional ultrasound urodynamics can be used to identify differences in bladder shape comparing individuals with and without OAB. This method may be used to identify a subset of OAB patients with abnormal bladder shapes which may play a role in the pathophysiology of their OAB symptoms.
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Ajalloueian F, Lemon G, Hilborn J, Chronakis IS, Fossum M. Bladder biomechanics and the use of scaffolds for regenerative medicine in the urinary bladder. Nat Rev Urol 2018; 15:155-174. [DOI: 10.1038/nrurol.2018.5] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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16
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Fagerquist MA, Sethi V, Skytteren E, Oden A. Intra-observer repeatability when assessing the foetal urinary bladder volume by the Virtual Organ Computer-aided AnaLysis and SUM-OF-CYLINDERS methods: A pilot study. ULTRASOUND (LEEDS, ENGLAND) 2018; 25:156-165. [PMID: 29410691 DOI: 10.1177/1742271x17709854] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 04/19/2017] [Indexed: 11/17/2022]
Abstract
Introduction The aim of this study was to compare the intra-observer repeatability when using two different methods for estimating the volume of foetal urinary bladders. Method The urinary bladders of 20 foetuses were documented by three-dimensional ultrasound. Standard deviation was compared when the volumes of identical bladder images were repeatedly estimated using the Virtual Organ Computer-aided AnaLysis and the experimental SUM-OF-CYLINDERS methods. Results No systematic deviation was found between the estimated volumes when using these two methods. Standard deviation was smaller for the SUM-OF-CYLINDERS compared to the Virtual Organ Computer-aided AnaLysis method (p < 0.0001). In relation to bladder volumes of 5-25 ml, standard deviation was 11-14% for the Virtual Organ Computer-aided AnaLysis and 4-5% for the SUM-OF-CYLINDERS method. Conclusions Using three-dimensional ultrasound images adapted for the Virtual Organ Computer-aided AnaLysis method, foetal urinary bladder volumes can also be estimated using the SUM-OF-CYLINDERS method. The SUM-OF-CYLINDERS method employs technical advances which may result in a lower standard deviation and therefore higher intra-observer repeatability.
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Affiliation(s)
- Mats A Fagerquist
- Department of Obstetrics and Gynecology, Innlandet Hospital Trust, Kongsvinger Hospital, Norway.,Department of Obstetrics and Gynecology, North Elfsborg County Hospital, Trollhattan, Sweden
| | - Vivek Sethi
- Department of Obstetrics and Gynecology, Akershus University Hospital, Lorenskog, Norway
| | - Eli Skytteren
- Department of Obstetrics and Gynecology, Innlandet Hospital Trust, Kongsvinger Hospital, Norway
| | - Anders Oden
- Chalmers University of Technology, Gothenburg, Sweden
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Sugi M, Kinoshita H, Yoshida T, Taniguchi H, Mishima T, Yoshida K, Yanishi M, Komai Y, Watanabe M, Matsuda T. The narrow vesicourethral angle measured on postoperative cystography can predict urinary incontinence after robot-assisted laparoscopic radical prostatectomy. Scand J Urol 2018; 52:151-156. [DOI: 10.1080/21681805.2018.1428683] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Motohiko Sugi
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
| | - Hidefumi Kinoshita
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
| | - Takashi Yoshida
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
| | - Hisanori Taniguchi
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
| | - Takao Mishima
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
| | - Kenji Yoshida
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
| | - Masaaki Yanishi
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
| | - Yoshihiro Komai
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
| | - Masato Watanabe
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
| | - Tadashi Matsuda
- Department of Urology and Andrology, Kansai Medical University, Osaka, Japan
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18
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Modelling Creep (Relaxation) of the Urinary Bladder. SERBIAN JOURNAL OF EXPERIMENTAL AND CLINICAL RESEARCH 2017. [DOI: 10.1515/sjecr-2016-0067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Abstract
We first present the results of an experiment in which the passive properties of the urinary bladder were investigated using strips of rabbit bladder. Under the assumption that the urinary bladder had orthopaedic characteristics, the strips were taken in the longitudinal and in the circumferential directions. The material was subjected to uniaxial tension, and stress-stretch curves were generated for various rates of deformation. We found that the rates did not have a significantly effect on the passive response of the material. Additionally, the stress-stretch dependence during relaxation of the material when exposed to isometric conditions was determined experimentally.
Next, we measured nonlinear stress-stretch dependence to determine the coefficients for this dependence in analytical form using a standard fitting procedure. The same approach was used to obtain the coefficients for the relaxation curves from the experimental data. Two constitutive laws, the nonlinear model for passive response and the creep model, were introduced within the shell finite element for geometrically and materially nonlinear analysis. We provide descriptions of the numerical procedures that were performed by considering the urinary bladder as a thin-walled shell structure subjected to pressure loading.
The developed numerical algorithm for the incremental-iterative solution was implemented into the finite element program, PAK. The response of the urinary bladder was calculated for continuous filling, and the numerical and experimental results were compared through cystometrograms (pressure-volume relationships). We also present comparisons of the shapes and volumes of the urinary bladder obtained numerically and experimentally. Finally, the numerical results of the creep response, when placed under constant internal pressure, are provided for various stages of deformation.
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Quantification of bladder wall biomechanics during urodynamics: A methodologic investigation using ultrasound. J Biomech 2017; 61:232-241. [PMID: 28835340 DOI: 10.1016/j.jbiomech.2017.07.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 06/20/2017] [Accepted: 07/22/2017] [Indexed: 01/22/2023]
Abstract
Overactive bladder is often characterized by biomechanical changes in the bladder wall, but there is no established method to measure these changes in vivo. The goal of this study was to develop a novel method to determine detrusor wall biomechanical parameters during urodynamics through the incorporation of transabdominal ultrasound imaging. Individuals with overactive bladder (OAB) underwent ultrasound imaging during filling. The fill rate was 10% of the cystometric capacity per minute as determined by an initial fill. Transabdominal ultrasound images were captured in the midsagittal and transverse planes at 1min intervals. Using image data and Pves, detrusor wall tension, stress, and compliance were calculated. From each cross-sectional image, luminal and wall areas along with inner perimeters were measured. In the sagittal and transverse planes, wall tension was calculated as Pves∗luminal area, wall stress as tension/wall area, and strain as the change in perimeter normalized to the perimeter at 10% capacity. Elastic modulus was calculated as stress/strain in the medial-lateral and cranial-caudal directions. Patient-reported fullness sensation was continuously recorded. Data from five individuals with OAB showed that detrusor wall tension, volume, and strain had the highest correlations to continuous bladder sensation of all quantities measured. This study demonstrates how detrusor wall tension, stress, strain, and elastic modulus can be quantified by adding ultrasound imaging to standard urodynamics. This technique may be useful in diagnosing and better understanding the biomechanics involved in OAB and other bladder disorders.
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Moulton DE, Sulzer V, Apodaca G, Byrne HM, Waters SL. Mathematical modelling of stretch-induced membrane traffic in bladder umbrella cells. J Theor Biol 2016; 409:115-132. [PMID: 27590325 DOI: 10.1016/j.jtbi.2016.08.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 03/21/2016] [Accepted: 08/24/2016] [Indexed: 12/11/2022]
Abstract
The bladder is a complex organ that is highly adaptive to its mechanical environment. The umbrella cells in the bladder uroepithelium are of particular interest: these cells actively change their surface area through exo- and endocytosis of cytoplasmic vesicles, and likely form a critical component in the mechanosensing process that communicates the sense of 'fullness' to the nervous system. In this paper we develop a first mechanical model for vesicle trafficking in umbrella cells in response to membrane tension during bladder filling. Recent experiments conducted on a disc of uroepithelial tissue motivate our model development. These experiments subject bladder tissue to fixed pressure differences and exhibit counterintuitive area changes. Through analysis of the mathematical model and comparison with experimental data in this setup, we gain an intuitive understanding of the biophysical processes involved and calibrate the vesicle trafficking rate parameters in our model. We then adapt the model to simulate in vivo bladder filling and investigate the potential effect of abnormalities in the vesicle trafficking machinery on bladder pathologies.
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Affiliation(s)
- D E Moulton
- Mathematical Institute, University of Oxford, Oxford, UK.
| | - V Sulzer
- Mathematical Institute, University of Oxford, Oxford, UK
| | - G Apodaca
- Departments of Medicine and Cell Biology, University of Pittsburgh, USA
| | - H M Byrne
- Mathematical Institute, University of Oxford, Oxford, UK
| | - S L Waters
- Mathematical Institute, University of Oxford, Oxford, UK
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21
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Shao IH, Chou CY, Huang CC, Lin CF, Chang YH, Tseng HJ, Wu CT. A Specific Cystography Pattern Can Predict Postprostatectomy Incontinence. Ann Surg Oncol 2015; 22 Suppl 3:S1580-6. [DOI: 10.1245/s10434-015-4847-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Indexed: 11/18/2022]
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22
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Abstract
Narrowing of the anastomotic area between the bowel segment and urinary bladder is known as "hourglass bladder." This report describes a rare case of hourglass bladder deformity occurring post-ileocystoplasty in a 14-year-old male. We describe the essential steps that should be taken during bladder augmentation to avoid such a complication, along with a discussion of the relevant literature. This case emphasizes the need to strictly adhere to the steps of augmentation cystoplasty to avoid this technical complication.
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Affiliation(s)
- Hamdan H. Alhazmi
- From the Division of Urology, Department of Surgery, College of Medicine and King Khalid University Hospital, King Saud University, Saudi Arabia
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23
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An Anatomical and Functional Perspective of the Pelvic Floor and Urogenital Organ Support System. ACTA ACUST UNITED AC 2015. [DOI: 10.1097/jwh.0000000000000033] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Abstract
Many urological studies rely on models of animals, such as rats and pigs, but their relation to the human urinary system is poorly understood. Here, we elucidate the hydrodynamics of urination across five orders of magnitude in body mass. Using high-speed videography and flow-rate measurement obtained at Zoo Atlanta, we discover that all mammals above 3 kg in weight empty their bladders over nearly constant duration of 21 ± 13 s. This feat is possible, because larger animals have longer urethras and thus, higher gravitational force and higher flow speed. Smaller mammals are challenged during urination by high viscous and capillary forces that limit their urine to single drops. Our findings reveal that the urethra is a flow-enhancing device, enabling the urinary system to be scaled up by a factor of 3,600 in volume without compromising its function. This study may help to diagnose urinary problems in animals as well as inspire the design of scalable hydrodynamic systems based on those in nature.
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Spirka T, Kenton K, Brubaker L, Damaser MS. Effect of material properties on predicted vesical pressure during a cough in a simplified computational model of the bladder and urethra. Ann Biomed Eng 2013; 41:185-94. [PMID: 22907256 PMCID: PMC3677772 DOI: 10.1007/s10439-012-0637-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 08/03/2012] [Indexed: 10/28/2022]
Abstract
Stress urinary incontinence is a condition that affects mainly women and is characterized by the involuntary loss of urine in conjunction with an increase in abdominal pressure but in the absence of a bladder contraction. In spite of the large number of women affected by this condition, little is known regarding the mechanics associated with the maintenance of continence in women. Urodynamic measurements of the pressure acting on the bladder and the pressures developed within the bladder and the urethra offer a potential starting point for constructing computational models of the bladder and urethra during stress events. The measured pressures can be utilized in these models to provide information to specify loads and validate the models. The main goals of this study were to investigate the feasibility of incorporating human urodynamic pressure data into a computational model of the bladder and the urethra during a cough and determine if the resulting model could be validated through comparison of predicted and measured vesical pressure. The results of this study indicated that simplified models can predict vesical pressures that differ by less than 5 cmH(2)O (<10%) compared to urodynamic pressure measurements. In addition, varying material properties had a minimal impact on the vesical pressure and displacements predicted by the model. The latter finding limits the use of vesical pressure as a validation criterion since different parameters can yield similar results in the same model. However, the insensitivity of vesical pressure predictions to material properties ensures that the outcome of our models is not highly sensitive to tissue material properties, which are not well characterized.
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Affiliation(s)
- Thomas Spirka
- Department of Biomedical Engineering, Cleveland Clinic Lerner Research Institute, Cleveland Clinic Main Campus, Mail Code ND20, 9500 Euclid Avenue, Cleveland, OH 44195, USA
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26
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Fry C, Sadananda P, Wood D, Thiruchelvam N, Jabr R, Clayton R. Modeling the urinary tract-computational, physical, and biological methods. Neurourol Urodyn 2011; 30:692-9. [DOI: 10.1002/nau.21131] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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27
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Novel Approach to Segment the Inner and Outer Boundaries of the Bladder Wall in T2-Weighted Magnetic Resonance Images. Ann Biomed Eng 2011; 39:2287-97. [DOI: 10.1007/s10439-011-0324-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Accepted: 05/03/2011] [Indexed: 10/18/2022]
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28
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Krywonos J, Fenwick J, Elkut F, Jenkinson I, Liu Y, Brunt J, Scott A, Malik Z, Eswar C, Ren X. MRI image-based FE modelling of the pelvis system and bladder filling. Comput Methods Biomech Biomed Engin 2010; 13:669-76. [DOI: 10.1080/10255840903446961] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Parekh A, Cigan AD, Wognum S, Heise RL, Chancellor MB, Sacks MS. Ex vivo deformations of the urinary bladder wall during whole bladder filling: contributions of extracellular matrix and smooth muscle. J Biomech 2010; 43:1708-16. [PMID: 20398903 DOI: 10.1016/j.jbiomech.2010.02.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2009] [Revised: 01/21/2010] [Accepted: 02/19/2010] [Indexed: 11/19/2022]
Abstract
As the complete understanding of urinary bladder function requires knowledge of organ level deformations, we conducted ex vivo studies of surface strains of whole bladders during controlled filling. The surface strains derived from displacements of surface markers applied to the posterior surface of excised rat bladders were tracked under slow filling with pressure and volume simultaneously recorded in the passive and completely inactivated states (i.e. with and without smooth muscle tone, respectively). Bladders evaluated in the passive state exhibited spontaneous contractions and larger average peak pressures (16.7 mm Hg compared to 6.4 mm Hg in the inactive state). Overall, the bladders exhibited anisotropic deformations and were stiffer in the circumferential direction, with average peak stretch values of approximately 2.3 and approximately 1.9 in the longitudinal and circumferential directions, respectively, for both states. Although bladders in the passive state were stiffer, they had similar average peak areal stretches of 4.3 in both states. However, differences early in the filling process as a result of a loss in smooth muscle tone in the inactive state resulted in longitudinal lengthening of 36%. Idealizing the bladder as a prolate spheroid, we estimated the wall stress-strain relation during filling and demonstrated that the intact bladder exhibited the classic stress-stretch relation, with a significantly protracted low stress region and peak stresses of 36 and 51 kPa in the longitudinal and circumferential directions, respectively. The present study fills a major gap in the urinary bladder biomechanics literature, wherein knowledge of the pressure-volume-wall stress-wall strain relation was explored for the first time in a functioning organ ex vivo.
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Affiliation(s)
- Aron Parekh
- Department of Bioengineering, Swanson School of Engineering, McGowan Institute, School of Medicine, 300 Technology Drive, Pittsburgh, PA 15219, USA
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WANG CC, NAGATOMI J, TOOSI KK, YOSHIMURA N, SACKS MS, CHANCELLOR MB. Biomechanics of Diabetic Bladders. Low Urin Tract Symptoms 2009. [DOI: 10.1111/j.1757-5672.2009.00041.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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31
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Affiliation(s)
- Margot S. Damaser
- From the Rehabilitation R & D Center, Hines VA Hospital, Hines, IL, USA, Urology Department, Loyola University Medical Center, Maywood, IL, USA
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Wang CC, Nagatomi J, Toosi KK, Yoshimura N, Hsieh JH, Chancellor MB, Sacks MS. Diabetes-induced alternations in biomechanical properties of urinary bladder wall in rats. Urology 2009; 73:911-5. [PMID: 19168204 DOI: 10.1016/j.urology.2008.11.026] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2008] [Revised: 11/24/2008] [Accepted: 11/26/2008] [Indexed: 11/26/2022]
Abstract
OBJECTIVES To determine whether diabetes mellitus and the associated changes in bladder function will trigger bladder wall tissue remodeling and concomitant alterations in the mechanical properties. We investigated the time course of changes in function and mechanical properties of diabetic and diuretic rat bladders using both in vivo and in vitro techniques METHODS Cystometry was performed at 2, 4, and 8 weeks on female Sprague-Dawley rats that had received either a single injection of streptozotocin (65 mg/kg intraperitoneally) or 5% sucrose in drinking water for the duration of the experiments. At each point, the biaxial mechanical properties of 10 x 10-mm tissue specimens obtained from the posterior part of bladder wall were quantified. The changes in overall tissue compliance and mechanical anisotropy as a function of time were examined RESULTS Both diabetic and diuretic conditions led to increases in bladder weight, bladder capacity, and in vivo compliance compared with the controls at all points tested. Under biaxial loading, all bladder wall tissues exhibited a nonlinear stress-strain relationship and mechanical anisotropy, with greater tissue compliance in the circumferential direction than in the longitudinal direction. Although the compliance of the bladder wall increased progressively and synchronously in both diabetic and diuretic bladders for < or = 4 weeks, only the diabetic bladders continued to increase the compliance for < or = 8 weeks (diabetic 0.64 +/- 0.04 vs diuretic 0.48 +/- 0.05, P = .03) CONCLUSIONS The results of our study have shown that diuresis mainly contributes to the "early" changes of mechanical properties of the bladder, with diabetes inducing additional "late" changes of mechanical properties of the rat bladders after 4 weeks.
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Affiliation(s)
- Chung Cheng Wang
- Department of Urology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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Regional biomechanical and histological characterisation of the passive porcine urinary bladder: Implications for augmentation and tissue engineering strategies. Biomaterials 2008; 30:266-75. [PMID: 18926570 DOI: 10.1016/j.biomaterials.2008.09.034] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Accepted: 09/11/2008] [Indexed: 02/01/2023]
Abstract
The aim of this study was to identify and quantify potential regional and directional variations in the quasistatic uniaxial mechanical properties of the passive urinary bladder wall. Overall, the lower body and trigone regions demonstrated the highest degree of directional anisotropy, whereas the ventral region demonstrated the least directional anisotropy. Significant regional anisotropy was found only along the apex-to-base direction. The dorsal and ventral regions demonstrated a significantly increased distensibility along the apex-to-base direction compared to the other bladder regions, whereas the trigone and lower body regions demonstrated the least distensibility. The trigone, lower body and lateral regions also demonstrated the highest tensile strength both at regional and directional levels. The study detected significant regional and directional anisotropy in the mechanical properties of the bladder and correlated this anisotropy to the distended and non-distended tissue histioarchitecture and whole organ mechanics. By elucidating the inhomogeneous nature of the bladder, the results from this study will aid the regional differentiation of bladder treatments in terms of partial bladder replacement with suitable natural or synthetic biomaterials, as well as the development of more realistic constitutive models of bladder wall biomechanics and improved computational simulations to predict deformations in the natural and augmented bladder.
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Abstract
We review mathematical and physical models of physiology of the organs of the urinary tract and their functions of producing, excreting, and voiding urine. Models for urine concentration in the kidney, urine flow in the ureters, bladder filling and emptying, urethral function during micturition, pelvic floor muscles, and neural control are reviewed in the context of their application to the development of new diagnostic and therapeutic techniques. The focus of this review is on modeling of physiology and function at the tissue and organ level, as almost all research to date has been done in those areas. Although physiological models of the lower urinary tract are in their infancy, they have the long-term potential to improve our understanding of physiological mechanisms, as well as to provide environments for simulation or testing in silico of new therapies and techniques.
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Affiliation(s)
- Thomas A Spirka
- Department of Biomedical Engineering, Cleveland Clinic Foundation, Cleveland, Ohio 44118, USA
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35
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Affiliation(s)
- Wendy M. Fallis
- Wendy M. Fallis is the director of research and evaluation at Victoria General Hospital, Winnipeg, Manitoba. Previously she was the clinical instructor in the intensive and postanesthetic care units
- Her area of research is thermoregulation and temperature measurement, with a focus on adult critical care patients
- She is a member of the research committee of the Canadian Association of Critical Care Nurses and the recipient of the Sigma Theta Tau 2003 Research Dissertation Award. The concerns expressed in this article arose during her doctoral research at the University of Washington in Seattle
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Schroder A, Uvelius B, Capello SA, Longhurst PA. Regional differences in bladder enlargement and in vitro contractility after outlet obstruction in the rabbit. J Urol 2002; 168:1240-6. [PMID: 12187275 DOI: 10.1016/s0022-5347(05)64633-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PURPOSE Bladder outlet obstruction leads to bladder enlargement and subsequent decreases in contractile function in vivo and in vitro. We determined whether there were regional differences in bladder wall properties and in vitro contractile responses after 2 weeks of bladder outlet obstruction. MATERIALS AND METHODS Male rabbits underwent cystometry. The bladder was then filled to 40 ml. and the surface was marked with 2-zero silk knots placed approximately 1 cm. apart. The distance between the knots was measured at 20, 40 and 80 ml. The animals then underwent the creation of surgical obstruction. After 2 weeks the obstruction was removed. Cystometry and measurements were repeated and strips were obtained from defined dorsal and ventral areas. Contractile responses to electrical field stimulation, adenosine triphosphate, carbachol and KCl were determined and compared with strips from unobstructed controls. RESULTS In vivo expansion during bladder filling occurred evenly throughout the bladder wall in controls and the contractile response to all stimuli was similar in ventral and dorsal strips. After 2 weeks of bladder outlet obstruction the upper dome expanded to a significantly higher degree than the lower bladder body. The response to all stimuli was significantly reduced after bladder outlet obstruction and there was a significantly decreased response to all stimuli in dorsal compared with ventral strips. Strips from the dorsal midline showed a relaxation response to electrical field stimulation at low frequencies, whereas all ventral strips contracted. CONCLUSIONS Functional remodeling after bladder outlet obstruction is a process that does not occur to the same extent throughout the bladder. The obstructed bladder is an inhomogeneous organ with significant regional differences in mechanical and pharmacological properties.
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Affiliation(s)
- Annette Schroder
- Department of Basic and Pharmaceutical Sciences, Albany College of Pharmacy and Division of Urology, Albany Medical College, Albany, New York, USA
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Regional Differences In Bladder Enlargement And In Vitro Contractility After Outlet Obstruction In The Rabbit. J Urol 2002. [DOI: 10.1097/00005392-200209000-00096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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van Duin F, Rosier PF, Rijkhoff NJ, van Kerrebroek PE, Debruyne FM, Wijkstra H. A computer model of the neural control of the lower urinary tract. Neurourol Urodyn 2000; 17:175-96. [PMID: 9590470 DOI: 10.1002/(sici)1520-6777(1998)17:3<175::aid-nau3>3.0.co;2-a] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Better understanding of the underlying working mechanism of the neural control of the lower urinary tract will facilitate the treatment of dysfunction with a neurogenic cause. We developed a computer model to study the effect of a neural control system on lower urinary tract behavior. To model the mechanical properties and neural control, assumptions had to be made. These assumptions were based, as much as possible, on knowledge and hypotheses taken from the literature. With valid assumptions, it should be possible to simulate normal as well as pathological behavior. To test the computer model, first, normal behavior of the lower urinary tract was simulated, and secondly, the known features of bladder outlet obstruction were simulated after the properties of the urethra were changed. The simulation results are comparable with measured data, so the assumptions on which the model is based could be valid. If the assumptions are valid, the feedback loops used in the model are also important feedback loops in vivo, and the model can be used to gain insight into the underlying mechanism of neural control.
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Affiliation(s)
- F van Duin
- Department of Urology, University Hospital Nijmegen, The Netherlands
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39
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40
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Damaser MS, Arner A, Uvelius B. Partial outlet obstruction induces chronic distension and increased stiffness of rat urinary bladder. Neurourol Urodyn 1996; 15:650-65. [PMID: 8916117 DOI: 10.1002/(sici)1520-6777(1996)15:6<650::aid-nau6>3.0.co;2-e] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
In order to identify the passive properties of the bladder during filling, we measured cystometrograms (CMGs) of rat urinary bladders that had been outlet obstructed for 6 weeks and age-matched controls in conscious, unrestrained animals and in fully relaxed whole bladders in an organ bath. In the organ bath, each bladder was allowed to empty passively at zero transmural pressure. The volume remaining was labelled zero pressure volume (ZPV) and was used as the reference volume to normalize contained volume, deriving wall stretch. Increased ZPV implies that the bladder contains more urine at low stresses and therefore is more distended. In awake animals, the obstructed bladder CMGs showed spontaneous contractions. The pressures between contractions were similar to those in CMGs performed in the organ bath, suggesting that passive properties determine the minimum pressures during filling in vivo. The ZPV of the obstructed and control bladders was 1.07 +/- 0.12 ml and 0.07 +/- 0.01 ml, respectively. The differences were significant (P < 0.01). The ZPV correlated with bladder weight and thus with degree of hypertrophy. Under conditions when weight cannot be determined, e.g., clinically, ZPV may provide a useful measure of the degree of chronic distension and bladder hypertrophy. The pressure-volume curves of the obstructed bladder CMGs in vitro varied between preparations. However, when pressure-volume was converted to stress-stretch using the law of Laplace, the obstructed bladders were all significantly stiffer than the controls. We confirmed this result by step-stretching relaxed bladder strips. The obstructed bladder strips again demonstrated stiffer stress-stretch curves than the controls.
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Affiliation(s)
- M S Damaser
- Department of Physiology, University of Lund, Sweden
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