Does the rate of extracorporeal shock wave delivery affect stone fragmentation?

Objectives. To evaluate the effect of the rate of shock wave delivery on st one fragmentation, because the optimal rate of shock wave administration ha s not yet been established. Methods. Standard phantom, ball-shaped, ceramic stones were placed in a net -like basket with a hole size of 2.2 mm and immersed in a specially designe d water bath coupled with the Econolith 2000 lithotripter. One hundred eigh teen stones (mean diameter 9.5 mm) were used. Shock waves were delivered at rates of 30, 60, 90, 120, and 150 shocks/min and at intensities of 15, 20, and 22.5 kV (electrohydraulic). The number of shocks required for complete fragmentation, determined by all fragmented particles falling through the basket holes, was recorded. Results. The most effective (fewer shocks needed for complete stone fragmen tation) rate of shock wave delivery was 60 shocks/min. A statistically sign ificant difference was demonstrated between the mean number of shocks requi red for complete stone fragmentation at the rate of 60 shocks/min and faste r rates at all energy levels (P < 0.01) but not between the rate of 60 shoc ks/min and the rate of 30 shocks/min at all energy levels. Conclusions. The rate of shock wave administration during extracorporeal sh ock wave lithotripsy seems to influence stone disintegration. We demonstrat ed that extracorporeal shock wave lithotripsy is most effective when waves are delivered at 60 shocks/min. (C) 1999, Elsevier Science Inc.