Effect of piezoelectric energy on porcine kidneys using the EDAP LT.02

EDAP International (Cambridge, Massachusetts) has developed a new piezoelectric lithotripter (LT.02) that differs from their earlier model (LT.01) in two important respects: method of stone visualization and available power. The LT.02 provides both in-line fluoroscopy as well as real time ultrasound. The maximum energy is 1400 Bar (compared with 1100 Bar in the LT.01). The purpose of this study was to determine whether treatment with the EDAP LT.02 piezoelectric lithotripter would cause significant renal injury in minipigs. Accordingly, 18 minipigs were divided into 3 groups of 6. Each group received a treatment of 20, 40 or 60 minutes; the power level and shock wave frequency were kept at maximal levels throughout the treatment period. Three pigs from each group were sacrificed at 72 hours (acute). The remaining 9 pigs were sacrificed 1 month following LT.02 treatment (chronic). Histopathologic analysis of the treated kidney revealed that 33% of the 9 acute pigs developed a small capsular hematoma, whereas 66% showed only a small parenchymal contusion ( < or = 1% of total renal volume). Among the chronic pigs, 66% had a small cortical scar, whereas 33% had no macroscopic pathology. Despite the differences in the number of shock waves delivered, these changes were evenly distributed among the 3 groups. Histologic acute changes included circumscribed areas of hemorrhagic infarction, vascular thrombosis with recanalization and focal tubular obstruction and damage. At 30 days, however, these acute injuries had completely resolved in 3 pigs and were only notable as minute areas of focal tubular loss in 6 pigs.