Effect of CO₂ and blood media on laser probe temperature

Abstract

Blood may limit laser ablation of arterial plaque by decreasing thermal energy transfer from metal-capped probes to arterial occlusions. Since a gas is a good insulator of heat, CO2 may be a better medium for laser recanalization. To study this possibility, a metal-capped fiber was positioned in a segment of blood-filled polyethylene tubing and activated with an argon laser. Probe temperatures were measured in blood and as the blood was displaced by flowing CO2 gas. Probe temperatures were higher at all powers studied in CO2 gas than in blood. Maximum probe temperatures averaged 518 +/- 24 degrees C after CO2 infusion versus 320 +/- 7 degrees C in blood, (P less than 0.0001). Blood aggregate formation was noted on the probe surface in blood but not in CO2 medium. Thus CO2 gas may be a preferable medium for laser recanalization, since higher probe temperatures are achieved, and the probe surface remains free of insulating blood coagulate.

Carbon Dioxide in Vascular Imaging and Intervention

“…Our previous study also demonstrated that C 0 2 gas perfusion facilitated more effective and safer ablation of human atheromatous plaques than did saline perfusion, even though the latter is usually infused in clinical laser angioplasty when using the sapphire probes (45). The greater laser ablation efficiency was related to 1) better insulation by C 0 2 gas than by saline, resulting in a stronger photothermal effect of laser heat-tissue interaction; 2) more effective removal of blood from the laser irradiation site by C 0 2 gas perfusion; and 3) better penetration of direct laser light through C 0 2 gas than through saline (37,44). Endovascular angioscopy.…”

Carbon Dioxide in Vascular Imaging and Intervention

“…Our previous study also demonstrated that CO 2 gas perfusion facilitated more effective and safer ablation of human atheromatous plaques than did saline perfusion, even though the latter is usually infused in clinica11aser angioplasty when using the sapphire probes (45). The greater laser ablation efficiency was related to 1) better insulation by CO 2 gas than by saline, resulting in a stronger photothermal effect of laser heat-tissue interaction; 2) more effective removal of blood from the laser irradiation site by CO 2 gas perfusion; and 3) better penetration of direct laser light through CO 2 gas than through saline (37,44). Endovascular angioscopy.…”