Morphological and surface temperature changes in femoral arteries following laser irradiation

A low-power carbon dioxide laser was to irradiate rat femoral arteries under the same conditions required to anastomose severed human arteries by thermal coagulation. Mean surface temperature changes were measured at the site of laser impact with the artery to evaluate the resultant histopathological changes as a function of laser power. More severe thermal coagulative changes, necrosis, and swelling resulted with increased laser power. Comparison of the temperature-time relationships showed that the peak surface temperature rise at the surface of these arteries was about 25°C for one pulse at 200 mW laser power, compared to an approximate 7°C rise for one pulse at 120 or 150 mW laser power. Increase in the surface temperature resulted in an increased severity of histopathological injury. These results showed that necrosis of medial layer smooth muscle cells occurred beyond the laser exposure site, suggesting that heat conduction could result in significant damage to reconnected vessel and could be a factor in the formation of a weak bond or an aneurysm.