SINGLE-LASER APPROACH FOR FLUORESCENCE GUIDANCE OF EXCIMER-LASER ANGIOPLASTY AT 308 NM - EVALUATION IN-VITRO AND DURING CORONARY ANGIOPLASTY

Background and Objective: Spectroscopic guidance of laser angioplasty has been attempted using a diagnostic He-Cd laser in addition to the t herapeutic laser system. This study evaluated a single-laser approach for simultaneous ablation and fluorescence excitation. Study Design/Ma terials and Methods: A spectroscopy system was coupled to a clinical X eCl excimer laser. Ablation of 162 human aortic samples in saline and blood with 45 mJ/mm(2) per pulse yielded 676 fluorescence spectra vali dated histologically. The same equipment was used in 16 patients for a ngioplasty of 18 coronary stenoses applying 500 to 1,725 pulses with 4 5 to 60 mJ/ mm under saline flushing. A total of 783 spectra were reco rded and validated by intracoronary ultrasound (categories: atheroma, fibrous plaque, calcified lesion). Results: In vitro, 5 types of spect ra could be differentiated: (1) atheroma, (2) fibrous plaque, (3) calc ified lesion in saline, (4) media, and (5) calcified lesion in blood. Discriminant analysis prospectively classified 576 validation spectra with the following sensitivity and specificity for each type: (1) 83.5 and 97.1%, (2) 85.7 and 96.8%, (3) 100 and 98.5%, (4) 98.1 and 99.3%, (5) 98.9 and 100%, respectively. In vivo, type 1, 2, 3, and 5 spectra were also observed, but not the media spectrum. The predominant sonog raphic category also prevailed in spectroscopy. Calcified lesions yiel ded type 3 and 5 as well as mixed spectra. Conclusions: Using an excim er laser for angioplasty allows combining ablation and fluorescence ex citation without a diagnostic laser. Principal types of atheroscleroti c lesions and the media can be differentiated spectroscopically with t his approach. (C) 1997 Wiley-Liss, Inc.