A new Piezoelectric Power Source and First Animal Experiments

Abstract

The disintegration efficacy of a new piezolectric power source has been measured in vitro using a Standard plaster model stone. Shock wave pressure profiles were determined in the focal area by a PVDF-membrane hydrophone. Compared to the Standard piezoelectric source the disintegration efficacy has been improved by about 50%. 11 beagle dogs with 21 renal units were treated with 2000 shocks in a Single session at the highest energy level by focusing the renal pelvis. Histopathological examinations were performed in 7 kidneys immediately after shock wave application, in 7 kidneys 6 weeks and in 7 kidneys 12 weeks after. Simultaneously CT-examinations and angiographies were performed. CT-findings and angiographies showed circumscribed intrarenal hematoma, perirenal edema but no larger perirenal injuries immediately after reatment. Corresponding to these findings histopathologically different early renal alterations were found like hematopyelon, intrarenal and subcapsular hematoma, papillary necroses, and vascular lesions. Despite the significant damage immediately after application of shock waves, only subtle alterations were observed 6 and 12 weeks after treatment: all kidneys showed small cordlike superficial and intrarenal scars along the pathway of the shock wave, only 1 of 14 kidneys showed a necrosis of the papillary apex. No vascular lesions could be found 6 and 12 weeks after treatment. With respect to further examinations the new generator with an improved efficacy of disintegration seems not to leave serious and permanent damage renal parenchyma. In comparison to the to the experimental data collected by the Standard piezogenerator comparable results have been achieved with the new power source.