Initial experience using a new type extracorporeal lithotripter with an anti-misshot control device.

Initial clinical trials using a new overhead piezoelectric extracorporeal lithotripter is presented. The advantages of this machine are the installation of an anti-misshot control device (AMCD) to prevent misshots to renal tissue, simplicity for ultrasound stone localization by the overhead type applicator, and elimination of necessity for anesthesia. Thirty patients with upper urinary tract calculi were treated by this machine with a success rate of 77% and stone destruction rate of 93%. No serious complication was observed. The AMCD functioned in such a manner that shock waves were generated only when the stone was in the focal region. Although there were AMCD nonfunctioning cases (small and deeply located stones), it is indicated that this machine is favorable for safe, extracorporeal lithotripsy.