Shock wave physics.

Extracorporeal shock wave lithotripsy has significantly altered the management of symptomatic renal and ureteral calculi. Yet in an effort to limit the potentially harmful effects of shock waves, while still maintaining or maximizing stone fragmentation, one must understand basic shock wave physics. This report presents a brief overview of the physical properties of shock waves and describes three different areas of shock wave physics investigation: measurement of shock wave pressures, assessment of stone fragmentation, and development of a stone phantom to allow the comparison of various lithotripsy devices. It is only through additional study of the basic physics of high-energy shock waves that we will be able to further enhance the clinical benefits of extracorporeal shock wave lithotripsy. Further understanding of the individual characteristics of a shock wave pressure field such as peak positive pressure, peak negative pressure, pulse duration, and size/shape of the focal region will allow the subsequent enhancement of stone fragmentation while minimizing the potential for shock wave injury to surrounding tissues.