In vitro comparison of thulium-holmium-chromium: YAG and argon ion lasers for welding of biliary tissue

Laser welding offers several potential advantages over suture closure, including improved healing, lack of a nidus for stone formation, and greater speed and ease. We examined in vitro gallbladder cystic duct welds created by two different systems, the thulmium-holmium-chromium (THC):YAG (2,150 nm) and argon ion (488-514 nm) lasers, in an effort to define suitable parameters for tissue fusion. Mean bursting pressures for argon welds were 95 mm Hg at 1.5 W CW and 26 mm Hg at 1.5 W, 50 msec chopped delivery. For the THC:YAG laser, the mean bursting pressure for welds created with 300 mJ pulses was 45 mm Hg. Full-thickness tissue fusion and limited collateral thermal damage were observed histologically for both the CW argon and pulsed THC:YAG welds. Examination of the suggested mechanisms of tissue fusion for these photothermal lasers suggests that increased duration of tissue heating at the appropriate temperature results in more extensive collagen crosslinking and a stronger weld.