Comparison of a pulsed dye laser and electrohydraulic lithotripsy on porcine gallbladder and common bile duct in vitro.

With the advent of minimal access biliary procedures there is a need for a safe intracorporal lithotripsy technique that can be used through small flexible endoscopes. Currently, the two techniques available are electrohydraulic lithotripsy and laser induced shock wave lithotripsy. In this study we compare the effect of a 504 nm coumarin pulsed dye laser and electrohydraulic lithotripsy on in vitro porcine gallbladder and common bile duct. Electrohydraulic lithotripsy at the lowest energy the generator would deliver caused perforation of both tissues in only a few pulses when a 1.9-F probe was placed in direct contact with the tissue. Energy from a 504 nm coumarin pulsed dye laser delivered through a 320-microns fiber placed in light contact with the tissue caused an energy-dependent perforation after 50 pulses in from none to 44% of tissues. It was also found that there was a higher incidence of perforation in more vascular than non-vascular tissue. When the EHL probe and the laser fiber were held 1-2 mm from the tissue surface, discharge of each resulted in no perforation. On histological examination of the tissues, the perforations were found to be very small with laser lithotripsy and considerably larger with the electrohydraulic lithotripsy. It was felt that laser lithotripsy in the clinical situation was likely to be much safer than electrohydraulic lithotripsy.