Influence of mineral components on laser-induced fluorescence spectra of calcified human heart-valve tissues

Laser-induced fluorescence (LIF) spectra of calcified human heart-valve tis sue and LIF spectra of macroscopic calcinosis fragments dissected from huma n heart valves were compared with LIF spectra of pig myocardium tissues. Ex citation was provided by an excimer laser with wavelength lambda = 248 nm. Fluorescence bands that were due to mineral and organic tissue components w ere identified by measurement of LIF spectra of macroscopic fragments of ca lcified tissues that had been heat treated at 700 degrees C. The studies sh owed that LIF spectra of calcified tissues include fluorescence emission fr om tryptophan, collagen, elastin, and a mineral component of tissue, hydrox ylapatite. The observed differences in LIF spectra of normal and calcified tissues with different pathologies may result not only from calcification-i nduced changes in relative collagen and elastin concentrations but also fro m additional (absent in normal heart tissue) fluorescence of hydroxylapatit e. The calcification-induced changes in the LIF spectra of human heart-valv e tissues, characterized by a 330/450 Mn ratio, were found to be quite appr eciable, which suggests that this ratio can be used with LIF measurements t o evaluate the degree of heart-tissue calcification. (C) 2000 Optical Socie ty of America OCIS codes: 300.2530, 140.2180, 170.6510.