In vitro study concerning the efficiency of the frequency-doubled double-pulse Neodymium : YAG laser (FREDDY) for lithotripsy of calculi in the urinary tract

Background and Objectives: In a preclinical study we have tested both in vi tro and in vivo, a new type of pulsed solid-state laser system that has not been applied in urology so far and has been developed for optimized intrac orporal lithotripsy of biliary, salivary, and urinary calculi. Study Design/Materials and Methods: Sixty one calculi from the human urinar y tract were split in vitro into fragments with a remaining particle size o f less than or equal to 2 mm using the prototype of a short;pulsed passivel y Q-switched and frequency-doubled double pulse Neodymium:YAG laser. In a s upplementary animal test, the bladder mucosa of five rabbits was directly e xposed to a highly rated laser beam to be able to assess the tissue lesion potential of the system. Results: All the 61 urinary calculi with different composition were success fully split in vitro within a short period of time (2.5 +/- 4.6 minutes). D uring histopathologic examination of the exposed bladder walls of the rabbi ts only a small tissue lesion potential with urothelium changes exclusively at the surface was ascertained. Conclusion: The high degree of fragmentation efficiency, the purchase and m aintenance costs, which due to its design are substantially lower in compar ison to other laser lithotriptors, and the high degree of safety during app lication make this new laser a real alternative not only to the present las er lithotripsy systems but also to common ballistic lithotriptors. Lasers S urg. Med. 25:38-42, 1999. (C) 1999 Wiley-Liss, Inc.