Can the use of different parameters and waveforms improve the results of intravesical electrical stimulation: a pilot study in the rat.

AIM

Intravesical electrical stimulation (IVES) with square wave pulses, low frequencies and short pulse durations has been used for decades in diagnosis and treatment of lower urinary tract dysfunction. The results are not always satisfying. Several parameters have been studied before but not the use of other waveforms and the effect of electrical charge. This study compares the effect of changing waveforms, frequencies, pulse durations, amplitudes and derived parameters in IVES.

METHODS

IVES, performed in seven female Sprague-Dawley rats, was given for 10 sec with constant current unipolar square or sawtooth pulses with different pulse durations (10, 20, or 100 msec), frequencies (5, 20, or 10 Hz) and amplitudes (2, 4, 6, and 8mA). Bladder pressure was recorded. Electrical charge and power were calculated.

RESULTS

Stimulation with the same frequency, same pulse duration and same amplitude showed significantly higher maximal pressure rises (max DeltaP) for square wave (all P < 0.05). Stimulation with the same frequency, same pulse duration and same electrical charge, gave no different max DeltaP for both waveforms (all P > 0.05). The charge and power could be reduced without changing max DeltaP, by lowering frequencies and/or shortening pulse durations.

CONCLUSIONS

Sawtooth pulses are equally effective as square pulses for inducing detrusor contraction during IVES with the same electric charge. Frequency and pulse duration had, in this study, a minor influence on the efficacy of IVES. Lower frequency and/or shorter pulse duration results in lower charge and power without changing stimulation efficacy. This finding can be important for the battery life of implanted stimulators and for patient's comfort.