Prevention of shockwave induced functional and morphological alterations: an overview

Experimental as well as clinical findings reported in the literature suggest that treatment with shock wave lithotripsy (SWL) causes renal parenchymal damage mainly by generating free radicals through ischaemia/reperfusion injury mechanism. Although SWL-induced renal damage is well tolerated in the majority of healthy cases with no permanent functional and/or morphologic side effects, a subset of patients with certain risk factors requires close attention on this aspect among which the ones with pre-existing renal disorders, urinary tract infection, previous lithotripsy history and solitary kidneys could be mentioned. It is clear that in such patients lowering the number of shock waves (per session) could be beneficial and has been applied by the physicians as the first practical step of diminishing SWL induced parenchymal damage. On the other hand, taking the injurious effects of high energy shock wave (HESW) induced free radical formation on renal parenchyma and subsequent histopathologic alterations into account, physicians searched for some protective agents in an attempt to prevent or at least to limit the extent of the functional as well as the morphologic alterations. Among these agents calcium channel blocking agents (verapamil and nifedipine), antioxidant agents (allopurinol, vitamin E and selenium) and potassium citrate have been used to minimize these adverse effects. Additionally, therapeutic application of these agents on reducing stone recurrence particularly after SWL will gain more importance in the future in order to limit new stone formation in these cases. Lastly, as experimental and clinical studies have demonstrated, combination of anti-oxidants with free radical scavengers may provide superior renal protection against shock wave induced trauma. However, we believe that further investigations are certainly needed to determine the dose-response relationship between the damaging effects of SWL application and the protective role of these agents.