CLINICAL-EXPERIENCE WITH ELECTROMECHANICAL IMPACTOR

The electromechanical impactor is a 3.0F electrohydraulic electrode wi thin a stainless steel sheath attached to a distal compression spring with a conical titanium tip. Eac electrical discharge causes a 2.7 mm. tip extension and a kinetic impact energy of 900 bar. It is 5F, flexi ble and placed within the straight working port of a 9.5F to 10.OF rig id or semirigid ureteroscope. A clinical trial was performed and 15 pa tients (16 ureters with calculi) were treated with this device. An upp er ureteral stone partially fragmented and migrated cephalad, 1 stone failed to break and was basket extracted, and there was 1 machine fail ure. The 13 other calculi were successfully broken to fragments less t han 5 mm. In 2 patients baskets were also used to remove the larger mo nohydrate fragments. A secondary procedure was required to basket a 4 mm. calcium oxalate monohydrate fragment in a patient with 3 ureteral calculi. The average size of the calculi was 14 mm. in largest diamete r. Excluding the machine failure, the average number of pulses require d for fragmentation was 764. The life of each device was 600 to 800 pu lses. Of the 15 cases 1 electrode was used in 10, 2 in 3 and 3 in 2. T here was no evidence of ureteral wall injury, abrasion or perforation. The electromechanical impactor is a safe and effective method of uret eral stone fragmentation.