title: A pilot study to measure dynamic elasticity of the bladder during urodynamics.
abstract: Previous studies using isolated strips of human detrusor muscle identified adjustable preload tension, a novel mechanism that acutely regulates detrusor wall tension. The purpose of this investigation was to develop a method to identify a correlate measure of adjustable preload tension during urodynamics.
  
  
  
  Patients reporting urgency most or all of the time based on ICIq-OAB survey scores were prospectively enrolled in an extended repeat fill-and-empty urodynamics study designed to identify a correlate of adjustable preload tension which we now call "dynamic elasticity." Cystometric capacity was determined during initial fill. Repeat fills to defined percentages of capacity with passive emptying (via syringe aspiration) were performed to strain soften the bladder. A complete fill with active voiding was included to determine whether human bladder exhibits reversible strain softening.
  
  
  
  Five patients completed the extended urodynamics study. Intravesical pressure (pves) decreased with subsequent fills and was significantly lower during Fill 3 compared to Fill 1 (P = 0.008), demonstrating strain softening. Active voiding after Fill 3 caused strain softening reversal, with pvesin Fill 4 returning to the baseline measured during Fill 1 (P = 0.29). Dynamic elasticity, the urodynamic correlate of adjustable preload tension, was calculated as the amount of strain softening (or its reversal) per %capacity (Δaverage pvesbetween fills/Δ%capacity). Dynamic elasticity was lost via repeat passive filling and emptying (strain softening) and regained after active voiding regulated the process (strain softening reversal).
  
  
  
  Improved understanding of dynamic elasticity in the human bladder could lead to both improved sub-typing and novel treatments of overactive bladder. Neurourol. Urodynam. 36:1086-1090, 2017. © 2016 Wiley Periodicals, Inc.
authors.affiliation: Division of Urology/Department of Surgery, Virginia Commonwealth University School of Medicine, Richmond, Virginia.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Colhoun
authors.affiliation: Division of Urology/Department of Surgery, Virginia Commonwealth University School of Medicine, Richmond, Virginia.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Klausner
authors.affiliation: Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University School of Engineering, Richmond, Virginia.
authors.forename: Anna S
authors.initials: AS
authors.lastname: Nagle
authors.affiliation: Department of Obstetrics and Gynecology, Virginia Commonwealth University School of Medicine, Richmond, Virginia.
authors.forename: Ashley W
authors.initials: AW
authors.lastname: Carroll
authors.affiliation: Departments of Emergency Medicine and Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, Virginia.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Barbee
authors.affiliation: Departments of Biochemistry and Molecular Biology and Pediatrics, Virginia Commonwealth University School of Medicine, Richmond, Virginia.
authors.forename: Paul H
authors.initials: PH
authors.lastname: Ratz
authors.affiliation: Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University School of Engineering, Richmond, Virginia.
authors.forename: John E
authors.initials: JE
authors.lastname: Speich
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D004548:Elasticity; D005260:Female; D006801:Humans; D059411:Lower Urinary Tract Symptoms / Q000503:physiopathology*; D008875:Middle Aged; D009130:Muscle, Smooth / Q000503:physiopathology; D009929:Organ Size / Q000502:physiology; D010865:Pilot Projects; D011312:Pressure; D013314:Stress, Mechanical; D001743:Urinary Bladder / Q000503:physiopathology*; D053201:Urinary Bladder, Overactive / Q000503:physiopathology*; D014563:Urodynamics
keywords: biomechanics; compliance; overactive detrusor function; urinary bladder; urodyanmics