Abstract
Laser-induced shock wave generation with a high-intensity Q-switched Nd:YAG laser depends on a laser-induced breakdown in a liquid with formation of an oscillating plasma bubble and cavitational effects. No thermal lesions in porcine urothelium so treated could be found. A new multifunctional laser for shock wave creation (20-nsec pulse duration) for urinary calculi and a free-running mode with millisecond pulses for biliary stones and coagulation of tissue has been developed for use with 320-, 400-, and 600-μm quartz fibers. In 118 patients with 120 calculi treated with laser-induced shock wave lithotripsy (LISL), complete fragmentation of 114 stones was obtained. In the remaining six calculi, laser disintegration was too slow. The efficacy of LISL can be augmented with highly dilute metallic solutions (iron-Ill dextran or magnesium chloride) by a self-focusing effect of the laser beam. With small (320-400 μm) quartz fibers, however, these solutions are not necessary for destruction of hard stones, as the laser focus is minimized.
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