ENDOSCOPIC ELECTROHYDRAULIC LITHOTRIPSY FOR CHOLEDOCHOLITHIASIS : DOG EXPERIMENTS AND PRELIMINARY CLINICAL EXPERIENCE

Abstract

Removal of a huge and hard common bile duct stone is often difficult even with the aid of retrograde basket extraction. Electrohydraulic surge current may be used to crush such a stone and facilitate the removal. An experimental study was undertaken in 12 dogs to investigate its effects and hazards using LITHORON (Walz Elektronik GmbH, West Germany) as an electrohydraulic surge current generator (Figure 1). After an in vitro study to choose an appropriate energy level (Table 2), cholesterol pigment calcium stones were crushed in the canine bile duct dilated by one-or two-week distal ligation. No single case of perforation was encountered (Table 3). Gross observation demonstrated localized redness of the bile duct mucosa in four of six animals where "ligation cholangitis" was minimal (Figure 4), which corresponded to an area of edema, submucosal hemorrhage and congestion revealed by a histological examination (Figure 5). Mucosal damage could not be identified in the remaining four due to diffuse cholangitic changes. Bile duct pressure monitored by infusion manometry via a cystic duct catheter unexpectedly showed a transient decrease on crushing the stone (Figure 6). Surge current ignition alone caused no remarkable pressure change. After the experimental study, the method was applied to a 36-year-old woman with a residual stone left unremoved even after repeated basket extraction procedures. The stone was crushed into several fragments and later easily removed. Electrohydraulic surge current is effective and relatively safe for endoscopic lithotripsy in the common bile duct, although care should be taken to avoid possible bile duct injury and the basket of the lithotripsy probe currently available needs to be improved to facilitate intraductal manipulatton.