[Extracorporeal shockwave biliary lithotripsy. Physical basis and clinical application].

Extracorporeal shock waves lithotripsy is a new procedure discovered and applied in the present decade to treat urinary and biliary stones. Shock waves are acoustic waves similar to sonic waves which follow the acoustic laws and therefore the shock waves can be refracted or reflected depending on the medium interface. Due to the high water content, the human body can be crossed by shock waves which eventually may be focused on the target stone. There are several commercially available shock waves generators, i.e. the spark gap emisors which were the first ones, and the piezoceramic and electromagnetic emisors. To focus the shock waves on a biliary stone the machines are provided with fluoroscopic or ultrasound devices or with both in the most advanced machines. Using an electromagnetic emisor (Lithostar plus) our group has treated 78 patients with biliary stones without analgesia or anesthesia. Total stone fragmentation was achieved in 85% of the cases. In patients with cholesterol gallstones who undergo lithotripsy, an adjuvant treatment with oral cholesterol solvent is mandatory. Extracorporeal biliary lithotripsy is free of mortality, and the morbidity is less than 5%.