Comparison of continuous-wave lasers for endarterectomy of experimental atheromas.

The standard surgical lasers, argon ion, neodymium-yttrium aluminum garnet, and carbon dioxide, are often operated as continuous wave lasers with specific uses. Clinical trials of laser therapy for arteriosclerotic cardiovascular disease are underway with all three lasers. Therefore, we compared these three lasers under controlled experimental conditions. A thoracoabdominal exploration was performed in 17 arteriosclerotic rabbits. The aorta was isolated, heparin administered, and multiple endarterectomies were performed in each rabbit with each of the lasers. A line of laser craters was created at the proximal and distal ends of an atheroma. Continuous-wave laser radiation was used to connect the craters and thereby form proximal and distal end points. The plaques were dissected free from the aorta with laser light and the end points were fused by laser. The aortas were removed for light microscopy and the animals were killed. The endarterectomy surfaces and end points were serially sectioned and graded according to light microscopic findings (1 = worst, 4 = best). Argon ion laser endarterectomy (N = 16) required 106 +/- 10 J/cm2. The surface score was 3.5 and end point score 3.4. Neodymium-yttrium aluminum garnet laser endarterectomy (N = 13) required 1,289 +/- 115 J/cm2 with a surface score of 2.4 (p less than 0.001 from argon ion) and an end point score of 1.3 (p less than 0.001 from argon ion). Carbon dioxide laser endarterectomy (N = 9) required 30 +/- 5J/cm2 with a surface score of 2.0 (p less than 0.001 from argon ion) and and end point score of 1.6 (p less than 0.001 from argon ion). Perforation occurred in one of 16 argon ion studies (technical error, not laser), in 11 of 13 neodymium-yttrium aluminum garnet studies, and in six of nine carbon dioxide studies. This study demonstrates that of the currently available clinical continuous-wave lasers, the argon ion laser is superior for endarterectomy of experimental atheromas.