Morphological changes following ESWL in the rat kidney.

Fifty four Wistar rats were treated with 500, 1,000 or 2,000 shock waves, using the modified DORNIER HM 3 system with the new SG40 shock wave generator. The animals were sacrificed after a period of 24 hours, 7 days or 35 days. Histological examination, scanning electron microscopy (SEM) and magnetic resonance imaging (MRI) were used to evaluate acute and long term effects after extracorporeal shock-wave lithotripsy (ESWL). Acute morphological changes such as glomerular bleeding, tubular dilatation, atrophy and partial necrosis occurred immediately after ESWL throughout the kidney. SEM revealed a tubular loss of microvilli and cilia. There was restitutio ad integrum of these diffuse lesions. The extent of the long term lesions was determined by the following mechanism: venous rupture occurred during ESWL, especially in thin arcuatae veins which are, tortuous their and run between two different tissue densities. This resulted in interstitial haematoma, demonstrable by MRI; in the long term groups, the haematomas progressed to interstitial fibrosis with segmental retraction of renal convexity. The blood supply in these areas was reduced and secondary changes such as glomerular-tubular atrophy and sclerosis followed. The degree to which long-term renal lesions resulted was determined by the extent of these changes, which were shock-wave dose dependent up to a dose of 2,000 shock waves.