Abstract
Laser angioplasty, for example XeCl excimer laser angioplasty, has gained more attention in addition to conventional
methods of surgical and interventional treatment of atherosclerotic diseases such as bypass operation and balloon
dilatation. Low degrees of thermal damage after ablation of atherosclerotic lesions have been achieved by XeCl excimer
laser at 308 nm. However, in most cases, laser ablation is not selective and normal arterial wall is also damaged. To
avoid complications such as severe dissections or perforation of the arterial wall in an angioplasty, a laser light source
with high ablation efficiency but low arterial wall injury is desirable. At atherosclerotic lesions, cholesterol accumulates
on the tunica intima by establishing an ester bond with fatty acids such as oleic acid, and thus cholesterol ester is the
main component of atherosclerotic plaques. Mid-infrared pulsed laser at 5.75 μm is selectively well absorbed in C=O
stretching vibration mode of ester bonds. The purpose of this study is to determine the effectiveness of nanosecond
pulsed laser at 5.75 μm irradiation of cholesterol ester in atherosclerotic plaques. In this study, we used a mid-infrared
tunable solid-state laser which is operated by difference frequency generation method, with a wavelength of 5.75 μm, a
pulse width of 5 nsec and a pulse duration of 10 Hz. It was confirmed that non-invasive interaction to normal thoracic
aortas could be induce by the parameters, the wavelength of 5.75 μm, the average power densities of 35 W/cm2 and the
irradiation time under 10 sec. This study shows that nanosecond pulsed laser irradiations at 5.75 μm provide an
alternative laser light source as an effectively cutting, less traumatic tool for removal of atherosclerotic plaque.
