Development and testing of second generation extracorporeal shock-wave lithotriptor.
The Northgate SD-3 extracorporeal shock-wave lithotriptor is a second generation device that utilizes an ultrasound-guided computer-assisted system for calculus localization. Focused electrohydraulic shock waves are generated in a movable membrane-covered ellipsoidal reflector. Pressure wave characteristics and energy output of the SD-3 and the Dornier HM-3 were tested and found to be comparable. The ultrasound unit was capable of identifying radiolucent calculi as well as calculus fragments 2-3 mm in size. The computer-assisted aiming system was found to be accurate to within 1 mm. The overall successful calculus fragmentation rate using an animal model was 80 percent with an 87.5 percent rate following machine modifications resulting in increased energy output.