TEMPERATURE FEEDBACK AND COLLAGEN CROSS-LINKING IN ARGON-LASER VASCULAR WELDING

A preliminary single-animal study of in vivo argon laser vascular weld ing was conducted using a canine model. The effects of temperature fee dback control and saline drip cooling on patency and collagen cross-li nking were investigated. The surface temperature at the centre of the laser spot was monitored using a two-colour infrared thermometer. The surface temperature was limited by either a saline drip or feedback co ntrol of the laser. Acute patency was evaluated and collagen cross-lin k assays were performed. Though both protocols yielded successful tiss ue fusion, welds maintained at a surface temperature of 50 degrees C u sing feedback control had an elevated cross-link count compared to con trols, whereas tissues irradiated without feedback control experienced a cross-link decrease. Simulations using the LATIS (LAser-TISsue) com puter code suggest that drip-cooled procedures achieve significantly h igher temperatures beneath the tissue surface than temperature feedbac k-controlled procedures. Differences between the volumetric heating as sociated with drip-cooled and feedback-controlled protocols may accoun t for the different effects on collagen cross-links. Covalent mechanis ms may play a role in argon laser vascular fusion.