Preliminary study of a dual CCD based ratiometric optical mapping system

A customized dual CCD based optical mapping system is designed and constructed for the purpose of applying ratiometry to the study of cardiac arrhythmia mechanisms. The system offers 490 frames per second data acquisition speed, 128 by 128 detector elements and 12 bits digitization. Each CCD camera is dedicated to imaging a specific region of the di-4-ANEPPS emission spectrum, through the use of appropriate filtering, the red region (635 +/- 27.5nm) and the green region (532nm +/- 19nm). The resulting two dimensional images collected from each spectrum region behaved consistently with the spectrum shift characteristics of di-4-ANEPPS, with the fluorescence intensity of the red region decreasing during action potential and the fluorescence intensity of the green region increasing during action potential. By taking the ratio of the two images, a ratiometric signal is constructed that offered improved uniformity in fluorescence intensity distribution, compared to the individual regional images.