Argon Laser Vascular Welding: The Thermal Component

Various mechanisms have been proposed for laser induced vascular welding. The conflict is partly due to the different laser parameters being used, different techniques, and the possible dual thermal and photochemical effects of lasers on tissues. This study examines the thermal aspects of welding medium diameter (4-8 mm) blood vessels. Six canine arteriovenous (A-V) fistulas were created by argon laser vessel fusion. Thermal images were concurrently recorded with a AGA thermal camera and computer analyzed. The welding was done at an energy fluence of 1100 J/cm 2 , using continuous saline irrigation for cooling. The thermal profiles revealed a maximum temperature of 48° C. In previous experiments, welding of microvessels has been achieved with CO 2 , Na:YAG and argon lasers. In our experience, welding of medium diameter arteriotomies and A-V fistulas was possible only with argon lasers. The thermal component induced by different laser wavelengths may be partly accountable for these observed differences in welding properties. Further studies are required to delineate the role of photochemical and thermal reactions in vascular tissue fusion by lasers.