Features and Acoustic Output of Five Electrohydraulic Lithotripters for Endoureteral Stone Treatment

Abstract

Five electrohydraulic lithotripters with probes of 3.3F or smaller were surveyed with special regard to endoureteral lithotripsy: the Walz Lithotron EL 23, the Storz Calcutript 27080 B, the Circon AEH-2A, the Wolf Riwolith 2038, and a prototype of a new Wolf lithotripter. Measurements were made using a PVDF needle-hydrophone in 0.9% NaCl at 10 mm from the probe. The results were recorded and computed by a digital oscilloscope. Peak pressure, rise time, and pulse width were registered, and the slope of the shock front and the pulse intensity integral were calculated. The applied energy ranged from 60 mJ to 1382 mJ per pulse. All four commercial lithotripters generate shock waves that cannot be varied in peak pressure or slope of the shock front. Three of the commercial lithotripters offer one or a few standard energy settings when a smaller probe is used. However, more energy is simply transferred by a broader pulse. With one device, more or less energy was transferred solely by varying the frequency of pulses within a selected time interval. The Wolf prototype was the only one provided with an infinitely variable setting within a wide range of energy, leading to pulses with higher peak pressures and steeper shock fronts.