Enhancement of pulsed-dye laser ablation of arterial tissues with blood medium: effects of laser-induced shock waves.

The influence of blood medium on tissue ablation by a pulsed dye laser and its selectivity for atheroma were investigated. The role of shock waves on tissue ablation was also evaluated. Normal and atherosclerotic human aortas were irradiated by a 480 nm pulsed dye laser activated at 5 Hz. The laser was coupled with a single 0.2 mm fiber (Uni-guide) (40 mjoules/pulse) or a multifiber catheter (14 x 150 microns) (100 mjoules/pulse). Shock waves were measured using a fluid-filled catheter connected to a strain gauge manometer. With the Uni-guide, pulse-dye lasing resulted in greater ablation of atheroma in blood (11.6 x 10(-3) mm3/joule, p less than 0.001 versus atheroma measured in saline and normal tissue in blood) followed by normal tissue in blood (2.5 x 10(-3)mm3/joule), atheroma in saline (1.71 x 10(-3)mm3/joule, p less than 0.05 versus normal tissue in saline), and normal tissue in saline (0.54 x 10(-3) mm3/joule). With the multifiber catheter, laser ablation was the greatest in atheroma in blood (0.55 +/- 0.26 mm3/joule p less than 0.001 versus atheroma in saline and normal tissue in blood), followed by normal tissue in blood (0.27 +/- 0.12 mm3/joule), atheroma in saline (0.14 +/- 0.15 mm3/joule, p less than 0.001 versus normal tissue in saline), and normal tissue in saline (0 mm3/joule). The ablation efficiency of the multifiber catheter was greater than that of the Uni-guide (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)