Thermal ablation of WHHLMI rabbit atherosclerotic plaque by quantum cascade laser in the 5.7-μm wavelength range

Abstract

We evaluated the utility of a compact and high-power quantum cascade laser (QCL) in the 5.7 μm wavelength range for less-invasive laser angioplasty. Atherosclerotic plaques mainly consist of cholesteryl esters. The wavelength of 5.75 μm is well absorbed in C=O stretching vibration mode of cholesteryl esters. Our previous study achieved to make cutting differences between a normal tunica intima of an artery and an atherosclerotic lesions using a nanosecond pulsed laser by difference-frequency generation (DFG laser) at the wavelength of 5.75 μm. For realizing a clinical application of this technique, a compact laser device is required. In this study, QCL irradiation effects to a porcine normal aorta were compared with DFG laser. In addition QCL irradiation effects to an atherosclerotic aorta of myocardial infarction-prone Watanabe heritable hyperlipidemic rabbit (WHHLMI rabbit) and a normal aorta were observed. As a result, the QCL could make cutting difference between the rabbit atherosclerotic aorta and the normal aorta. On the other hand, the QCL induced more thermal damage to porcine normal aorta than the DFG laser at the irradiation condition of comparable ablation depth. In conclusion, the possibility of less-invasive and selective treatment of atherosclerotic plaques using the QCL in the 5.7 μm wavelength range was revealed, although improvement of QCL was required to prevent the thermal damage of a normal artery.