Laser induced shock wave lithotripsy

Abstract

AbstractLaser induced shock wave lithotripsy has the potential to become a standard procedure in the endourologic management of urinary stone disease. To date, there are two fairly well established laser systems for laser induced shock wave lithotripsy in clinical practice, the Q‐switched Nd: YAG and the flashlamp pumped dye laser. —The Q‐switched Nd: YAG Laser (20 ns pulses) is distinguished by the high stone selectivity of its coupler systems, but the necessity of a coupler and its fairly small rate of conversion of light into mechanical energy present a grievous draw back. Furthermore, the minimal outer diameter of the transmission system is 1.8 mm, limiting its range of application. —By using longer pulses in the range of 1–2 μs that can be produced with both a flashlamp pumped dye or a low‐gain solid state laser with the same pulse energies (∽ 50 mJ) these disadvantages can be overcome. —Pulses of the dye laser can be passed through a highly flexible and uncomplicated 200 μm quarz fiber. Laser lithotripsy is performed with the bare fiber tip placed directly in contact with the stone at repetition rates of up to 10 Hz. The quality of the fiber tip in contact with the stone is uncritical. —Biological evaluation of damage caused by direct irradiation shows that both laser systems cause minor damage of different degree. —Our newest development is a optical feedback regulation system to avoid damage to adjacent tissue even under direct contact, enabling intracorporeal lithotripsy without endoscopic control.