Intravascular delivery of laser energy with metal-capped optical fibers: the potential hazard of distal embolism.

To assess the risk of embolism resulting from plaque fragmentation during laser angioplasty with metal-capped optical fibers, laser energy of 4, 8, and 12 W for 10 or 20 seconds was delivered through these fibers to 60 coronary endarterectomy segments fitted in a silicone tube filled with saline solution. Twenty specimens manipulated in the same way but without delivering laser energy were used as controls. The effluent was filtered through in-line filters of 225, 70, and 25 microns. Treatment with laser energy resulted in weight loss and shortening of the specimens compared to control specimens (23 +/- 4 mg versus 5.4 +/- 0.8 mg; p less than 0.001 and 0.2 +/- 0.02 mm versus 2.5 +/- 0.5 mm; p less than 0.001). However, this also produced significant debris formation for all combinations of power and time (up to 275 +/- 38 micrograms versus 155 +/- 21 micrograms in controls). Results of scanning electron microscopy showed the presence of fragments up to 300 microns in diameter. Another potential hazard of laser angioplasty with metal-capped optical fibers in thromboembolism. This was studied by delivering laser energy through metal-capped fibers during perfusion with aliquots of blood at 5 or 40 ml/min. At each flow rate nine aliquots were treated with either 4, 8, or 12 W for 3, 6, or 9 seconds and a tenth was used as a control aliquot. The effluent was filtered with five filters between 225 microns and 25 microns.(ABSTRACT TRUNCATED AT 250 WORDS)