Time-resolved fluorescence spectroscopy of the heart tissues

Abstract

During the heart surgery there is a possibility to harm the conduction system of the heart (HCS), which may cause dangerous obstruction of the heart functionality. The muscular origin makes it complicated to distinguish HCS from the surrounding tissues; therefore, there is an immense necessity to visualise HCS during the operation time. Optical methods carry information about intrinsic properties of the tissue and provide the unique possibility to study the objects non-invasively. The experiments were performed on the human heart tissue specimens ex vivo. HCS, myocardium (MC), and connective tissue (CT) were preliminary marked by a pathologist and histologically approved after the spectral measurements. The spectrometer FLS920 (Edinburgh Instruments) was used for steady state and time-resolved fluorescence registration. Fluorescence was exited using a 405 nm pulsed laser. Spectral analysis revealed that at least three fluorophores are responsible for the emission in the region of 430-550 nm. According to the lifetimes, the fluorescing constituents in all tissues should be the same. The fractional components of fluorescence intensity revealed a similar composition of MC and HCS; however, quantitative differences were observed between HCS and CT.

Application of time-resolved autofluorescence to label-free in vivo optical mapping of changes in tissue matrix and metabolism associated with myocardial infarction and heart failure

“…We report the application of a compact optical fiber based instrument, which combines single point time-resolved spectrofluorometry and steady-state diffuse reflectance spectroscopy, to investigate the diagnostic potential of autofluorescence and reflectance in cardiac tissue. Although autofluorescence lifetime measurements have already been applied to studies of isolated cardiac cells [4,42] and in a number of other cardiovascular applications [21,43,44], its application to measurements of the whole heart remains limited [45]. To the best of our knowledge, this is the first in vivo application of TRFS to the study of cardiac tissue.…”