Absence of distal emboli during in vivo laser recanalization

We used an argon laser to recanalize occluded arteries in vivo and to determine the extent of any particulate matter resulting from the procedure that might cause embolization. Thrombosis was achieved by balloon de-endothelialization and thrombin injection in 12 canine femoral or carotid arteries in six dogs. The resulting totally occlusive thrombi (2.5-8.5 cm in length) were laser treated in situ 2-29 days after formation, using laser tip power outputs of 0.8-3.4 W. The treated arterial segment was perfused before, during, and after the recanalization procedure with 1,000 ml of heparinized saline. All saline passing through the artery was collected and studied by filtration through 20-micron pore filter paper; 50-ml unfiltered aliquots were studied by automated, calibrated cell counting and microscopically after centrifugation and staining. All vessels except one were completely recanalized. Filtration yielded a thin reddish, dust-like residue. No large fragments were found in 11 of 12 effluents. The residue after centrifugation was almost entirely composed of erythrocytes plus one to four 20-30-micron strands of amorphous cellular material per high-power field. Cell counting showed that 99.1% of the material in the effluents was smaller than 9.37 micron. These results demonstrate the presence of some filterable debris following laser recanalization of intraarterial thrombi, but it probably lacks any physiologic significance. Further study of this effect of laser recanalization is needed.