Purpose: Carotid artery stenting (CAS) has become a widely used option for treatment of carotid stenosis. Although
technical improvements have led to a decrease in complications related to CAS, distal embolism continues to be a
problem. The purpose of this research was to investigate the usefulness of optical methods (Time-Resolved Laser-
Induced Fluorescence Spectroscopy [TR-LIFS] and reflection spectroscopy [RS] as diagnostic tools for assessment of
vulnerable atherosclerotic lesions, using rabbit models of vulnerable plaque.
Materials & Methods: Male Japanese white rabbits were divided into a high cholesterol diet group and a normal diet
group. In addition, we used a Watanabe heritable hyperlipidemic (WHHL) rabbit, because we confirmed the reliability
of our animal model for this study. Experiment 1: TR-LIFS. Fluorescence was induced using the third harmonic wave of
a Q switch Nd:YAG laser. The TR-LIFS was performed using a photonic multi-channel analyzer with ICCD
(wavelength range, 200 - 860 nm). Experiment 2: RS. Refection spectra in the wavelength range of 900 to 1700 nm
were acquired using a spectrometer.
Results: In the TR-LIFS, the wavelength at the peak was longer by plaque formation. The TR-LIFS method revealed a
difference in peak levels between a normal aorta and a lipid-rich aorta. The RS method showed increased absorption
from 1450 to 1500 nm for lipid-rich plaques. We observed absorption around 1200 nm due to lipid only in the WHHL
group.
Conclusion: These methods using optical analysis might be useful for diagnosis of vulnerable plaques.
Keywords: Carotid artery stenting, vulnerable plaque, Time-Resolved Laser-Induced Fluorescence
KEYWORDS: Ultraviolet radiation, Simulation of CCA and DLA aggregates, Arteries, Animal model studies, Angiography, Helium cadmium lasers, Blood, Silicon, Laser therapeutics, Modulation
We studied whether prophylactic low-intensity ultraviolet light (UV) irradiation reduces development of delayed cerebral vasospasm in rabbit model. Eleven rabbits had carotid angiography and placement of silicon sheaths around the right common carotid artery (CCA). Just before the placement, CCAs of 6 in the 11 animals were adventitiously exposed to UV (10 mJ/mm2) emitted from a helium-cadmium laser (wavelength equals 325 nm). Sheaths were filled with autologous blood in all of 11 animals. Vasospasm developed 24 to 48 hours (Day 2) later. The CCA luminal diameter without UV irradiation was 77% of the Day 0 state. The prophylactic laser treatment reduced the development of vasospasm, 90% of the Day 0 state. Histological examination of the treated CCA revealed extended smooth muscle cells. There was no endothelial damage. These results suggest that UV is effective for prophylaxis of cerebral vasospasm.
We investigated the photovasorelaxation with intravascular transluminal irradiation using in vivo model. A 2.5 Fr. catheter was inserted in the femoral artery of a rabbit under anesthesia. A 400 micrometers diameter quartz fiber was inserted through the catheter. The catheter was withdrawn from the distal end to the proximal end of the exposed femoral artery without laser irradiation in order to observe the mechanical dilation by the procedure. The femoral artery lumen was irradiated by a Helium-Cadmium(He-Cd) laser (wavelength; 325 nm) with 8 mW through the fiber during 30 s. We carried out that the laser irradiation produced vasorelaxation (185% on the average) compared with mechanical vasodilation (150% on the average) with angiography. The results suggest that intravascular transluminal irradiation with low-power UV laser might be applicable to the relief of acute arterial vasospasm.
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