SHOCK WAVE-INDUCED RENAL LESION IN THE CANINE MODEL - INFLUENCE OF GENERATOR VOLTAGE AND SHOCK-WAVE NUMBER IN THE ACUTE STUDY

Using the newly-developed electromagnetic shock wave source of the Modulith, the shock wave-induced kidney trauma was systematically evaluated by acute studies with a kidney model. Shock waves generated by a laboratory lithotripter coupled to a waterbath were applied to 38 kidneys under ultrasound localization. The generator voltage varied between 11 and 20 kV, the shock wave number between 25 and 2500. The generator voltage correlated with the extent of renal lesion, which was classified into 4 grades (at a constant shock wave number of 1500/2500): no macroscopical trauma (grade 0) could be detected at 11 - 12 kV. Petechial bleeding was observed in the renal medulla as a typical grade 1 lesion at 13 kV. At 14 - 16 kV, a grade 2 lesion occurred, characterized by a cortical and subcapsular hematoma or by perirenal ecchymosis. A perirenal hematoma, representing a grade 3 lesion, was induced- by a generator voltage between 17 and 20 kV The shock wave number also showed a correlation with the degree of trauma: 25 - 300 shock waves (20 kV) caused a grade 2 lesion, 900 - 2500 impulses a grade 3 lesion. Independent of the shock wave number, an arterial rupture was detected at this high generator voltage. Concerning the morphology of the shock wave-induced renal trauma, bleeding is most predominant. Necrosis of parenchymal cells seems to be a secondary effect. Real-time ultrasound scanning proved to be a sensitive tool for detection of kidney lesions during shock wave application. Experimental results are confirmed by clinical findings.