INTERDISCIPLINARY EXPERIENCE WITH THE LITHOGNOST - IMPACT OF OPTICAL FEEDBACK-CONTROLLED STONE DETECTION IN LASERTRIPSY

We report on the first experience with a new lasertripsy system, the Lithognost, a rhodamine G dye laser with a wavelength of 595 nm, a pulse duration of 3-mu-sec, a fiber tip energy of 50 to 120 mj/pulse, a repetition rate of 1 to 10 Hz, and a core diameter of 200 to 340-mu-m. The main feature of this laser is the automatic stone detection device. The intensity of the reflected laser light is analyzed, and the pulse energy is automatically blocked when the neighboring ureteral tissue is targeted. To date, 36 patients with ureteral calculi and 8 patients with bile duct calculi have been treated. All ureteral stone patients had undergone at least one previous unsuccessful session of extracorporeal lithotripsy (SWL). In 29 cases, lasertripsy (LISL) was performed under ureteroscopic vision (7.0F-9.5F), whereas in 7 cases, "blind" fluoroscopy-controlled LISL was carried out with a specially designed ureteral catheter. All patients were stented after each procedure. Six calculi were pushed up during ureteroscopy and treated successfully by SWL. Of the 30 remaining stones, 25 (83%) were fragmented by the laser: in 11 patients solely with the laser ("smash and go" technique) and in 14 cases with adjuvant use of forceps or the Dormia basket. Forceps extraction of nonfragmented calculi was necessary in only five cases. No laser-related complications were observed. The feedback-controlled stone-detection device, together with the high efficacy of this dye laser system, proved to be the decisive factors for successful and safe treatment, even on blind application.