Morphological correlates of urinary enzyme loss after extracorporeal lithotripsy

Effect of shock wave reapplication on urinary n-acetyl-beta-glucosaminidase in canine kidney

OBJECTIVE

Renal tubular damage can be assessed with the aid of urinary dosing of N-acetyl-beta-glucosaminidase (NAG) and it is possible to demonstrate a significant correlation between shock wave and damage to renal parenchyma. The objective of this study was to assess the effect of shock wave reapplication over urinary NAG in canine kidney.

MATERIALS AND METHODS

The authors submitted 10 crossbred dogs to 2 applications of 2000 shock waves in a 24-hour interval in order to assess urinary NAG values after 12, 24, 36 and 48 hours.

RESULTS

Twelve hours following the first shockwave application there was an increase in NAG of 6.47 +/- 5.44 u/g creatinine (p < 0.05). Twelve hours and 24 h following the second application there was no increase in the urinary enzyme, -2.56 +/- -7.36 u/g creatinine and 2.89 +/- -7.27 u/g creatinine, respectively (p > 0.05).

CONCLUSION

Shock wave reapplication with a 24-hour interval did not cause any increase in urinary NAG.

Evaluation of heat shock protein 70 expression in renal parenchyma subjected to shockwave lithotripsy

PURPOSE

In this experimental study in a rabbit model, renal parenchymal heat shock protein 70 (hsp70) levels were assessed in an attempt to evaluate the traumatic effects of high-energy shockwaves (HESW), which have been found to induce transient ischemia during the procedure.

MATERIALS AND METHODS

Eighteen white New Zealand rabbits, each weighing 3 to 5 kg, were included in the study. The animals were divided into three groups, and various numbers of shockwaves (1000, 1500, or 2000) were applied to the same kidney of all animals under fluoroscopic localization with a Stonelith V5 lithotripter. Untreated contralateral kidneys were evaluated as controls. Following HESW application, the treated and untreated kidneys were removed surgically after 24 hours or 7 days. Tissue hsp70 levels were assessed by an immunohistochemistry method.

RESULTS

During early follow-up (24 hours), both treated and untreated kidneys demonstrated moderate to severe hsp70 positivity. The number of positive tubules increased as the number of shockwaves increased, and positivity became more evident, possibly because of a higher degree of tissue damage. Contralateral kidneys demonstrated a limited degree of hsp70 positivity, although it was not as evident as in the treated kidneys. Assessment of tissue hsp70 levels during late follow-up (7 days) demonstrated moderate or limited degrees of positivity in the treated kidneys. Limited or no positivity could be demonstrated in the untreated kidneys during this period.

CONCLUSIONS

Taking the known traumatic effects of HESW and the results of this study into account, the increasing positivity of hsp70 in parallel with the increasing number of shockwaves led us to think about a possible limited degree of ischemia induced by this procedure, as the traumatic effects of HESW were pronounced, as judged by tissue hsp70 positivity.

The effect of discharge voltage on renal injury and impairment caused by lithotripsy in the pig

The present study was designed to determine the effects of shock wave voltage (kV) on lesion size and renal function induced by shock wave lithotripsy (SWL) in the 6- to 8-wk-old pig. Each SWL-treated pig received 2000 shock waves at 12, 18, or 24 kV to the lower pole calyx of one kidney. A group of sham SWL pigs served as time controls. Bilateral GFR, renal plasma flow (RPF), and para-aminohippurate (PAH) extraction were measured 1 h before and 1 and 4 h after SWL in all treated and sham animals. The kidneys were removed at the end of each experiment for morphometric analysis. The SWL-induced lesion increased significantly in size as shock wave energy was increased from 12 to 24 kV. PAH extraction, a measure of tubular function, was not significantly affected at 12 kV, was transiently reduced at 18 kV, and was reduced for the duration of the experiment at 24 kV. GFR and RPF, however, were significantly and similarly reduced at the 1 h post-SWL period at all three kilovolt levels. At the 4-h post-SWL period, both GFR and RPF had returned to baseline levels. Lesion size and tubular injury were correlated with changes in kilovoltage, while changes in renal hemodynamics were already maximal at the lowest discharge voltage. These findings suggest that renal microvessels are highly sensitive to shock waves and that frank injury to tubules and vessels may be more closely related to discharge energy than is renal blood flow.