Bioeffects of extracorporeal shock wave lithotripsy: a worry or not?

Update on shock wave lithotripsy technology

PURPOSE OF REVIEW

Since the first patient was successfully treated with extracorporeal shock wave lithotripsy in 1980, its rapid acceptance and widespread use have championed this form of stone therapy as the treatment of choice for the majority of renal and ureteral calculi. Worldwide clinical series have documented the efficacy and safety of shock wave lithotripsy.

RECENT FINDINGS

Shock wave lithotripters have undergone modifications of the source for generation of shock waves, focusing, and even localization techniques since the introduction of the original Dornier HM3 lithotripter. Yet the basic concepts remain the same: to produce an acoustic wave that can be focused at a specific location for stone fragmentation. Safety and efficacy of the different generations of lithotripters is well documented. Indications and utilization of shock wave lithotripsy have expanded, with clinical efficacy approaching or exceeding that of other modalities of minimally invasive surgery. Complications, however, can arise as a result of shock wave therapy.

SUMMARY

This review provides an update of the latest shock wave technology, reviewing the clinical indications and efficacy of treatment and discussing the potential adverse events associated with shock wave lithotripsy.

Management of lower pole nephrolithiasis: a critical analysis

The results of extracorporeal shock wave lithotripsy (ESWL*) and percutaneous nephrostolithotomy for the treatment of lower pole nephrolithiasis were examined in 32 consecutive patients undergoing percutaneous nephrostolithotomy at the Methodist Hospital of Indiana and through meta-analysis of publications providing adequate stratification of treatment results. Of 101 cases managed with percutaneous nephrostolithotomy 91 (90%) were stone-free, a result significantly better than that achieved with ESWL (1,733 of 2,927 stone-free, 59%). Stone-free rates with percutaneous nephrostolithotomy were independent of stone burden, whereas stone-free rates with ESWL were inversely correlated to the stone burden treated. The morbidity of patients undergoing percutaneous nephrostolithotomy at our hospital was minimal, with a mean hospital stay of 4.7 +/- 2.8 days. No blood transfusions were required. All patients became stone-free. The percentage of urolithiasis patients with lower pole calculi is increasing. Because of the significantly greater efficacy of percutaneous nephrostolithotomy for lower pole calculi, particularly stones larger than 10 mm. in diameter, further consideration should be given to an initial approach with percutaneous nephrostolithotomy.

Renal stone disease in autosomal dominant polycystic kidney disease

Nephrolithiasis is an important manifestation of autosomal dominant polycystic kidney disease (ADPKD), which occurs in approximately 20% of patients. It should always enter the differential diagnosis of flank pain in patients with ADPKD. The diagnosis is hindered by the distorted anatomy of the polycystic kidneys and the frequent occurrence of parenchymal and cyst wall calcifications, and requires demonstration of the relationship to the collecting system by intravenous urography and/or computed tomography. Computed tomography is the most sensitive imaging technique for detection of stones or calcifications, whereas intravenous urography is the most sensitive for visualization of the intrarenal collecting system. Precaliceal tubular ectasia can be detected in 15% of patients with ADPKD and nephrolithiasis, but this association may not be specific to ADPKD. The composition of the stones is most frequently uric acid and/or calcium oxalate. Metabolic factors are important in their pathogenesis. Distal acidification defects may be important in a few patients, while an abnormal transport of ammonium, low urine pH, and hypocitruria are the most common abnormalities. The treatment of nephrolithiasis in patients with ADPKD is not different from that in patients without ADPKD. Extracorporeal shock wave lithotripsy and percutaneous nephrostolithotomy in patients with early disease and normal renal function are not contraindicated.