Selective pulsed dye laser thrombus ablation : Can contrast media replace fiberoptics in pulsed dye laser delivery system?

ABSTRACT

BACKGROUND: The absorption coefficient of the arterial thrombus is 7~10 fold greater than that of arterial wall for the wave lengths of 480~510nm. This fact suggest that selective laser thrombus ablation could be possible without ablation of surrounding vessel wall in this wavelengths. METHODS: Pulsed dye laser(488nm, 2.2micros, 10Hz) thrombus ablation was investigated in viro. Ablation threshods of whole blood clot and normal aortic tissue were measured using a 1.5mm multifiber laser catheter(14x150microm). Whole blood clot samples were lasered to determine the ablation efficiency. The operative fluence was 80mJ/mm2. The transmission efficiencies of 488nm wave length through various transmission media(including contrast media of saline solution) were observed using a upsilon Fr arterial sheath filled with transmission medium. RESULTS: The ablation threshold for fresh whole blood clot in saline solution was 36.5+/-2.4mJ/mm2(9.0+/-0.6mJ/pulse) as compared with that for normal human aortic tissue which was over 405mJ/mm2(>100mJ/pulse)(p<0.05). Pulsed dye laser ablated whole blood clot with the efficiency at 0.026+/-0.009gm/J. The role of thrombus ablation was 0.154+/-0.056gm/min. This experiment also revealed that cotrast media(Ultravist(R) 370, Schering, France) allows light tramission of 488nm wave length at relatively high efficiency. CONCLUSIONS: These facts suggested that selective pulsed dye laser ablation of fresh intravascular thrombi can be obtained at relatively low energy fluence without damaging the surrounding vascular tissue. A new pulse dye laser delivery system such as catheter system or native coronary artery filled with contrast media, which has large area of frontfiring face, may facilitate a safe and effective thrombus ablation.