In vitro fragmentation of gallstones: comparison of electrohydraulic, electromagnetic and piezoelectric shockwave lithotripters.

To compare the fragmentation efficiency of three different shockwave systems, 63 human gallstone triplets were disintegrated in vitro using an electrohydraulic (MPL 9000, Dornier), an electromagnetic (Lithostar Plus, Siemens) and a piezoelectric (Piezolith 2300, R. Wolf) lithotripter. Since each stone triplet was obtained from the same gallbladder, the concrements of one such set were identical in physicochemical parameters. According to the maximal diameter, the calculi were divided into group A (6 to 15 mm) and group B (16 to 30 mm). Shockwave application was terminated when residual fragments measured 4 mm or less. Forty-five triplets were fragmented at energy settings mainly used in clinical treatment of patients with gallbladder stones (MPL 9000: 20 kV; Lithostar Plus: setting 9 (maximal); Piezolith 2300: setting 3). The fragmentation endpoint was achieved in group A (n = 3 x 36) with the Piezolith 2300 after median 150 (range = 50 to 500) pulses and with the Lithostar Plus after 150 (50 to 750) pulses compared with 500 (50 to 1,500) pulses using the MPL 9000 (p less than 0.01). In group B (n = 3 x 9) the Lithostar Plus (median = 750, range = 250 to 1,250 pluses) required fewer discharges than the Piezolith 2300 (1,250, 250 to 2,500 pulses; p less than 0.05) and the MPL (1,500, 500 to 1,600 [upper limit] pulses; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)