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.