title: Low amplitude rhythmic contraction frequency in human detrusor strips correlates with phasic intravesical pressure waves.
abstract: OBJECTIVE
  Low amplitude rhythmic contractions (LARC) occur in detrusor smooth muscle and may play a role in storage disorders such as overactive bladder and detrusor overactivity. The purpose of this study was to determine whether LARC frequencies identified in vitro from strips of human urinary bladder tissue correlate with in vivo LARC frequencies, visualized as phasic intravesical pressure (pves) waves during urodynamics (UD).
  
  
  METHODS
  After IRB approval, fresh strips of human urinary bladder were obtained from patients. LARC was recorded with tissue strips at low tension (<2 g) and analyzed by fast Fourier transform (FFT) to identify LARC signal frequencies. Blinded UD tracings were retrospectively reviewed for signs of LARC on the pvestracing during filling and were analyzed via FFT.
  
  
  RESULTS
  Distinct LARC frequencies were identified in 100% of tissue strips (n = 9) obtained with a mean frequency of 1.97 ± 0.47 cycles/min (33 ± 8 mHz). Out of 100 consecutive UD studies reviewed, 35 visually displayed phasic pveswaves. In 12/35 (34%), real pvessignals were present that were independent of abdominal activity. Average UD LARC frequency was 2.34 ± 0.36 cycles/min (39 ± 6 mHz) which was similar to tissue LARC frequencies (p = 0.50). A majority (83%) of the UD cohort with LARC signals also demonstrated detrusor overactivity.
  
  
  CONCLUSIONS
  During UD, a subset of patients displayed phasic pveswaves with a distinct rhythmic frequency similar to the in vitro LARC frequency quantified in human urinary bladder tissue strips. Further refinements of this technique may help identify subsets of individuals with LARC-mediated storage disorders.
authors.affiliation: Department of Surgery/Division of Urology, VCU Medical Center, West Hospital, Virginia Commonwealth University School of Medicine, 7th Floor, Room 7205, 1200 East Broad Street, PO Box 980118, Richmond, VA, 23298-0118, USA.
authors.forename: Andrew F
authors.initials: AF
authors.lastname: Colhoun
authors.affiliation: Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University School of Engineering, Richmond, VA, USA.
authors.forename: John E
authors.initials: JE
authors.lastname: Speich
authors.affiliation: Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Lauren F
authors.initials: LF
authors.lastname: Cooley
authors.affiliation: Department of Surgery/Division of Urology, VCU Medical Center, West Hospital, Virginia Commonwealth University School of Medicine, 7th Floor, Room 7205, 1200 East Broad Street, PO Box 980118, Richmond, VA, 23298-0118, USA.
authors.forename: Eugene D
authors.initials: ED
authors.lastname: Bell
authors.affiliation: Department of Emergency Medicine, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: R Wayne
authors.initials: RW
authors.lastname: Barbee
authors.affiliation: Department of Surgery/Division of Urology, VCU Medical Center, West Hospital, Virginia Commonwealth University School of Medicine, 7th Floor, Room 7205, 1200 East Broad Street, PO Box 980118, Richmond, VA, 23298-0118, USA.
authors.forename: Georgi
authors.initials: G
authors.lastname: Guruli
authors.affiliation: Departments of Biochemistry and Pediatrics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Paul H
authors.initials: PH
authors.lastname: Ratz
authors.affiliation: Department of Surgery/Division of Urology, VCU Medical Center, West Hospital, Virginia Commonwealth University School of Medicine, 7th Floor, Room 7205, 1200 East Broad Street, PO Box 980118, Richmond, VA, 23298-0118, USA. adam.klausner@vcuhealth.org.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Klausner
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D009130:Muscle, Smooth / Q000502:physiology* / Q000503:physiopathology; D011312:Pressure; D001743:Urinary Bladder / Q000502:physiology* / Q000503:physiopathology; D053201:Urinary Bladder, Overactive / Q000503:physiopathology; D014563:Urodynamics
keywords: Fourier analysis; Overactive; Smooth muscle; Urinary bladder