Login to Access Video or Poster Abstract: MP63-07
Sources of Funding: Support provided by NIH grant R01DK101719 and the VCU Presidential Research Quest Fund.

Introduction

Human detrusor smooth muscle (DSM) can exhibit low amplitude rhythmic contractions (LARC) which may contribute to overactive bladder (OAB) in some patients. The aim of this study was to develop an objective method to identify LARC during urodynamics (UD), categorize patients with significant LARC, and potentially begin to characterize a LARC-mediated OAB/detrusor overactivity subtype.

Methods

An algorithm was developed to analyze UD filling data in low volume (1st 410 seconds) and high volume (final 410s) regions. Fast Fourier Transform (FFT) analysis identified the frequency (F) in the 1-6 cycle/min range associated with the maximum amplitude of the vesical pressure (P_ves) in each region (Fig 1). A patient-specific range of interest corresponding to F ± 0.5 cycles/min was determined. P_ves and P_abd amplitudes were analyzed separately to identify both significant (higher than average) and independent (distinct from P_abd) P_ves signals. To be significant, P_ves amplitude must be > 1.35 standard deviations (SD) above average P_ves amplitude. To be independent, the P_abd amplitude must be < 1.35 SD above the average P_abd amplitude. SD of 1.35 was chosen using an iterative process in 0.05 SD increments to identify the maximum number of significant and independent signals.

Results

This algorithm was used to retrospectively analyze 43 consecutive UD studies which included 25 (14 neurogenic, 11 idiopathic) with detrusor overactivity (58%). The average age of the entire group was 55±2 years and included 14 men and 29 women. FFT analysis identified a significant and independent P_ves signal in 12/43 patients (28%) of which 8/12 (67%, 5 neurogenic, 3 idiopathic) had detrusor overactivity. The average age of patients with significant and independent signals was 54±5 years and included 6 men and 6 women.

Conclusions

Analysis of LARC during UD testing identified a subset of patients with a significant and independent slow wave frequency in P_ves. Further refinements of this technique may help identify subsets of individuals with LARC-mediated OAB/detrusor overactivity.

Funding

Support provided by NIH grant R01DK101719 and the VCU Presidential Research Quest Fund.