Change in laser‐induced arterial fluorescence during ablation of atherosclerotic plaque

Abstract

Analysis of the change in arterial fluorescence during plaque ablation may provide the basis for developing a fluorescence-guided ablation system capable of selective plaque ablation without risk of vessel perforation. Accordingly, fluorescence spectra were recorded from 91 normal and 91 atherosclerotic specimens of cadaveric human aorta. The ratio of the laser-induced fluorescence intensity at 382 nm to 430 nm (LIF ratio) was capable of classifying these specimens with an 89% accuracy with a threshold value of 1.8 (atherosclerotic greater than or equal to 1.8, normal less than 1.8). To characterize the change in fluorescence during plaque ablation, mechanical plaque ablation with a cold microtome was performed on 16 atherosclerotic aortic specimens. Fluorescence spectra were recorded serially after each 100 microns of plaque ablation; recordings revealed a change in fluorescence spectra from atherosclerotic to a normal pattern. With an LIF ratio of 1.8 to signal termination of plaque ablation, 15 of the atherosclerotic plaques had a residual plaque thickness less than 200 microns; one specimen had a residual plaque thickness of 300 microns. No specimen demonstrated ablation of the media. There was a statistically significant correlation between LIF ratio and plaque thickness (r = .73, P less than .001), but considerable variation in LIF ratio existed at each thickness. Therefore, laser-induced fluorescence spectroscopy is capable of discriminating atherosclerotic from normal aorta and of signaling completion of plaque ablation.

Photobleaching of Arterial Fluorescent Compounds: Characterization of Elastin, Collagen and Cholesterol Time‐resolved Spectra during Prolonged Ultraviolet Irradiation

“…Fading of the 390 nm fluorescence exceeded 50% when the total fluence was 12 mJ/mm2. Fluorescence spectroscopy has been widely investigated for quantification of artery tissue composition using pulsed and continuous-wave laser sources with excitation at 306-476 nm (4,5,21,26). Table 2 summarizes the conditions of irradiation for representative studies of artery tissue and fluorescent compounds.…”

Autofluorescence spectroscopy using a XeCl excimer laser system for simultaneous plaque ablation and fluorescence excitation

“…In 1985, Kittrell and colleagues [26] reported normal arterial wall in vitro by analyzing autoa spectrofluorimeter. Subsequently, various lasers were used as light Sources for the in vitro excitation of arterial fluorescence: an argon ion laser operating at 458 nm [27], a nitrogen laser at 337 nm [28, 291, a dye laser emitting between 305 and 310 nm [301 or at 476 nm ~311, or a H~-c~ laser operating at 325 nm [32][33][34][35][36]. The H~-c~ A two-laser system with a dye laser emitting at a of480 nm for tissue ablation and autofluorescence has been evaluated in patients with peripheral vascular disease of the lower ex-and for lipid plaques were essentially the Same as according to algorithm (I1) for media and lipid that a fibrous plaque could be differentiated from fluorescence spectra after excitation a t 480 nm in lesions in cave knee, there was a peak at 470 nm followed by laser was also used in viva on humans [37].…”

Excimer laser spectroscopy: Influence of tissue ablation on vessel wall fluorescence

“…Laser-light induced tissue fluorescence has been studied extensively in the past [1][2][3][4][5] and has been shown to be dependent on the severity of the histologic alterations and the intimal thickness of the vessel wall. A close correlation between the atherosclerotic changes and the fluorescence of the vessel wall has been reported by Bosshart et al in necropsy tissue specimens.…”