Laser-induced fluorescence (LIF) recognition of the structural compositionof porcine heart valves

Reconstruction and replacement of heart valves with grafts from pig tissue is a common procedure. However, bioprosthetic valves wear out in a shorter time span than mechanical valves. Bioprosthetic valve structure may contrib ute to degenerative changes that lead to valve failure, There is, at presen t, no method to examine the structure of a tissue valve prior to implant. L aser-induced fluorescence (LIF) of natural fluorophores is an elegant metho d developed for the detection of tumors, dermal lesions and atherosclerosis . We have studied LIF as a potential diagnostic technique for analysis of v alvular tissue. Using excimer laser excitation, we examined natural fluores cence recorded from porcine aortic, mitral and pulmonary valves. All three valve outflow surface tissue layers are less fluorescent at 390-450 nn than the inflow layers. Immunohistochemical analysis of collagen I and elastin content in inflow and outflow surface layers of all three valves correlated well with LIF intensities and dI/d lambda values at selected wavelengths, In conclusion, the differences observed in emitted LIF from valve surface l ayers are found to correlate well with diversity in the structural protein content. The LIF spectroscopic measurements may provide an appropriate tool for examination of tissue valve structure prior to use for implantation.