In order to develop a reliable, laser-induced, fluorescence-guided, angioplasty system, fluorescence spectra were recorded during exposure of normal and atherosclerotic cadaveric aortic tissue to argon ion laser irradiation. A characteristic increase in the fluorescence signal in the 520-560 nm spectral region for atheromatous tissue was observed after treatment of the samples with a tetracarboxylate ion dye (BTC). This allowed the development of a simple algorithm (based on the intensity difference) and a subsequent index of discrimination between normal and atheromatous tissue. Our results suggest that monitoring of this index through the catheter could enhance selective ablation.