Selective removal of atherosclerotic plaque with a quantum cascade laser in the 5.7 µm wavelength range

Abstract

Atherosclerotic plaques consist mainly of cholesteryl esters, and the C=O stretching vibration mode of cholesteryl esters strongly absorbs radiation at a wavelength of 5.75 µm. For clinical application of less-invasive laser angioplasty with 5.75 µm, a compact laser is required. Quantum cascade lasers (QCLs) are semiconductor lasers that can emit radiation in the mid-IR range. In this study, the potential of the QCL for less-invasive laser angioplasty was evaluated. At the average power density of 180 W/cm2, the atherosclerotic aorta was ablated for the irradiation time of 1 s or more, whereas the normal aorta was ablated for more than 10 s. This demonstrates that selective ablation of the atherosclerotic aorta was achieved. However, strong coagulation and carbonization were observed. For reducing thermal effects, improving the pulse structure is required. In conclusion, the QCL achieved the selective ablation of the atherosclerotic lesions, which indicates the potential of the QCL.