INFLUENCE OF CARBON-DIOXIDE GAS PERFUSION TO THERMAL DISTRIBUTION OF SAPPHIRE PROBE - A COMPARATIVE-STUDY WITH SALINE

RATIONALE AND OBJECTIVES. A previous study confirmed that the direct l aser-thermal conduction of the sapphire probe with carbon dioxide gas perfusion increased the width of the laser-recanalized channel. This c aused us to further investigate the thermal distribution characteristi cs of the sapphire probe when lasing with CO2 gas perfusion. METHODS. The surface temperature of a sapphire probe in a circulation model usi ng 37 degrees C flowing whole blood was measured. Two hundred and sixt een measurements were obtained by directly contacting a flexible therm ocouple wire onto the sapphire probe at different sites: 1) metal conn ector; 2) lateral side of the sapphire crystal; 3) top of the sapphire crystal; and 4) 3 mm in front of the sapphire probe. During lasing wi th a neodymium-yttrium-aluminum garnet (Nd-YAG) laser, the CO2 gas or saline was infused through the sapphire probe at different flow rates. RESULTS. The lateral side of the sapphire crystal was heated up to 75 degrees C when lasing without any perfusion, but up to 220 degrees C when lasing with CO2 gas perfusion. At all four sites, the mean temper ature increases were statistically higher (P < .01) with CO2 gas than with saline perfusion. The mean peak temperatures increased with incre asing flows of CO2 gas perfusion and decreased with increasing flows o f saline perfusion. CONCLUSIONS. The thermal conduction from the sapph ire probe can be significantly enhanced by increasing flows of CO2 gas perfusion. This may play an important role in creating a greater diam eter of the recanalized channel and in better delaying the formation o f restenosis or re-occlusion after laser recanalization of atheromatou s arteries.