Physics and technique of shock wave lithotripsy (SWL)

Abstract

Extracorporeal shock wave lithotripsy (SWL) is a gentle and noninvasive treatment procedure suitable for a wide range of kidney and ureteral stones. The technique makes use of extremely short transient (<1 m s) pressure pulses with pressure amplitudes up to 100 MPa (1,000 bars). Brittle stone material breaks into small pieces, whereas biological tissue passes shock waves without signi fi cant damage. Different shock wave generation principles (electrohydraulic, piezoelectric and electromagnetic) are presented, and basic shock wave parameters are discussed with regard to stone fragmentation and side effects. Modern lithotripsy devices utilize fl uoroscopic and/or echographic imaging methods for stone localization and targeting. As with all sophisticated technologies, SWL requires comprehensive technical and anatomical skills to fully bene fi t from this exciting treatment method.