Feasibility of clinical laser angioplasty will depend upon safe and efficacious removal of obstructing intravascular atheroma. However, different laser sources (visible, infrared, or ultraviolet) and variable lasing parameters (pulsed vs continuous) result in different tissue effects due to different mechanisms of tissue ablation. Since particulate debris after atheroma removal may result in hemodynamically important intraarterial embolic events, it becomes necessary to characterize the photo-products of laser ablation before these techniques can be considered for clinical application. Thus, we determined the size distribution of particular debris after laser ablation of full thickness holes in normal necropsy aorta under saline using a pulsed ultraviolet excimer laser and a continuous argon laser. For both laser sources, more than 80% of particulate debris was less than 3 microns in size, suggesting that the majority of photo-products are too small to cause microvascular obstruction. Interestingly, the excimer laser, despite less thermal tissue injury, caused a 5- 10 fold greater number of particles which are greater than 5 microns in size. Since pulsed excimer laser tissue ablation creates shock waves, this mechanism of tissue ablation may result in a larger particle size distribution which may be disadvantageous.
