Laser induced shock wave lithotripsy--biologic effects of nanosecond pulses

Laser energy of a Nd-YAG laser (1064 nm. wave length, 8 nsec pulse duration) was directed against various tissue cultures and the urothelium of the ureter, bladder and kidney parenchyma in pigs. Single pulse energy was 50 to 120 mJ with a repetition rate of 20 Hz. Urothelium and kidney parenchyma were irradiated in seven pigs. Tissue samples were examined histologically and electron microscopically directly, two, four, eight and 12 days after irradiation. No macroscopic lesion could be found. Maximum energy caused a small 'rupture cone' of 40 micron. depth. No thermic effects or necrosis resulted, so that no harm is to be expected with unintentional irradiation during laser stone disintegration.