Lithotripsy with a Q-switched alexandrite laser system. Preliminary in vivo and in vitro results.

An alexandrite laser system which emits a wavelength of 750 nm, has recently been proposed as a substitute for the pulsed-dye laser (504 nm) for laser lithotripsy. We have carried out in vitro lithotripsy trials in order to evaluate the efficiency of a flashlamp pumped Q-switched alexandrite laser. In the first experiment, we compared the Q-switched alexandrite laser to the pulsed-dye laser with respect to their effectiveness in fragmentizing urinary and model stones (HMT target stones). In the second experiment, we evaluated the effect of Q-switched alexandrite radiation on the urinary wall (bladder, ureter, renal pelvis and liver) of animals (Wistar rats and rabbits) under general anesthesia. In conclusion, the alexandrite laser system is comparable to the pulsed dye laser. The 750-nm wavelength involves minimal risk of damage to the urinary tract and constitutes a safe alternative, especially during blind lithotripsy. It is a compact solid-state system, with no toxic chemical agents as laser material.