The influence of electrode shape on the performance of electrohydraulic lithotripters

This study was performed to determine the advantages and disadvantages of the two shapes of electrodes (flat and conical) commonly used in electrohydraulic extracorporeal shock wave lithotripters. Hundreds of measurements made on profiles obtained from a piezoelectric pressure gauge in an underwater shock wave research device showed that conical electrodes are more convenient than flat electrodes, since they produce shock waves with larger compressional amplitudes, less misfires and a better reproducibility, having similar widths and rise times. In an attempt to improve the effectiveness and duration of the electrode tips, a new shape was designed that proved to be more reliable and suitable for lithotripsy than the conventional flat or conical electrodes. Experiments with calculi models placed in the focal region of the shock wave generator seem to confirm the results obtained from pressure measurements.