INTERSPERSION OF FRAGMENTED FIBERS SPLINTERS INTO TISSUE DURING PULSED ALEXANDRITE LASER LITHOTRIPSY

Laser induced shockwave lithotripsy (LISL) on artificially inserted human renal calculi was realized in explanted pig ureters. A pulse stretched Alexandrite solid state laser was used at 750nm. Pulses of 350ns and 1-mu-s duration were transmitted through a 250-mu-m all silica fiber onto a stone surface, keeping the fiber tip in contact with a stone close to the ureter wall. The high power density of the 350ns pulses lead to an optical breakdown inside the distal fiber tip causing fiber fragmentation of about 28mm/100 pulses. Deep penetration of the fiber fragments into the ureter wall was proven histologically. Fiber fragmentation was avoided by increasing the pulse duration up to 1-mu-s. Risks for patient treatment caused by short pulse lithotripsy are discussed.