Clinical experience using the Wolf Piezolith device at 2 British stone centers.

Machines using the principle of piezoelectric extracorporeal shock wave lithotripsy have been developed. This has allowed the prospect of painless treatment for renal and ureteral calculi. The experience with use of 2 Wolf Piezolith machines for 1 year is presented. Different second generation lithotriptors have varying techniques of production of shock waves and different imaging methods. The Wolf Piezolith device uses ultrasound imaging and piezoelectric crystals for shock wave generation. Between June 1987 and May 1988, 545 patients 5 to 84 years old were treated with the Wolf Piezolith device. Of these patients 2-month followup data are available for 367 (398 renal units). Outpatient treatment was used routinely. For renal calculi complete fragmentation (into particles less than 2 mm. in size) was achieved in 94 per cent of the patients, with 53 per cent being completely free of stone at 2 months. For ureteral stones treated in situ the best results were obtained in the upper and lower ureter. Over-all, 62 per cent of the patients required more than 1 treatment, with the number of treatment sessions required increasing with the size of the stone treated. Morbidity was low. Ultrasound imaging has proved to be as effective as x-ray imaging. Compared to Dornier HM-3 lithotripsy, installation and running costs were low. The machine offers a favorable alternative to first generation lithotriptors.