Acoustic characterization and assessment of renal injury with a broad focal width electrohydraulic lithotripter

This study provides an independent assessment of a novel lithotripter (LG-380, Tissue Regeneration Technologies), marketed as having a long-life self-adjusting spark gap electrode and producing a low-pressure, broad-focal-zone acoustic field. For acoustic characterization we coupled the therapy head of the lithotripter to a water tank and mapped the field using a fiber-optic hydrophone (FOPH-500, RP Acoustics). At the target point of the lithotripter, the peak positive pressure (P +) remained relatively stable (~19±5 MPa at power level 9) during the 6000 shock waves (SWs) lifetime of the electrode. The position of maximum P + (~35 MPa at PL9) was 35mm distal to target point and shifted progressively toward the therapy head as the electrode aged, reaching the target point (while reducing to P + ~20 MPa) after ~5000 SWs. This was likely due to a slight movement in position of the self-adjusting spark gap—changing the focus of the shock wave and the dimensions of the focal volume of the lithotripter. Kidney ...