Optical micromapping in cardiac tissues and cells

The authors have developed an optical micromapping system which consists of two individual setups with one common laser as excitation light source. One setup is designed to monitor excitation spread in cardiac tissue preparations in the mm-range, the other one is capable to monitor excitation phenomena in single cardiomyocytes. The time resolutions achieved are about 100 μs for the tissue setup (256 pixels, spatial resolution down to 84 μm), and about 20 μs for the cell setup (24 pixels, spatial resolution down to 14 μm). The green line of an argon ion laser (514 nm, up to 2 W) was used to excite fluorescence of various cardiac preparations of rats and guinea pigs which were stained with the potential sensitive dye di-4-ANEPPS. The authors´ measurements revealed discontinuous propagation occurring in microscopic areas in cardiac tissues as well as complex excitation phenomena in single cardiomyocytes when stimulated by extracellular electrical fields