Evaluation of a synchronous twin-pulse technique for shock wave lithotripsy: a prospective randomized study of effectiveness and safety in comparison to standard single-pulse technique.

OBJECTIVE: To asses the efficacy and safety of bidirectional synchronous twin-pulse extracorporeal shock wave lithotripsy (ESWL) compared with standard ESWL. PATIENTS AND METHODS: Between March 2003 and December 2006, 240 patients with a radio-opaque single renal stone of 10 mm the rate for the failure of disintegration was 13.3% for the DLS vs 1.4% for the TH (P = 0.009). For stones of 10 mm it was 78.1% and 66.7%, respectively (P = 0.14). The median (range) number of sessions in both groups was 2 (1-5). After ESWL urinary NAG levels were increased significantly in both groups; in the TH group it declined below the level before ESWL after 2 days, while in the DLS group it remained high after 7 days. In the DLS group four patients developed subcapsular or parenchymal haematoma after ESWL, vs none in the TH group. There was loss of corticomedullary differentiation after ESWL in three patients in the DLS group and only one in the TH group. In the DLS group there was a statistically significantly decrease in bilateral renal perfusion after ESWL, but no changes in the TH group. CONCLUSIONS: Synchronous twin-pulse ESWL has clinical advantages over standard ESWL in terms of safety and efficacy.