Development of optical mapping system with real-time feedback stimulation in the heart

Recent studies showed that electrical stimuli in the excitable gaps during ventricular fibrillation (VF) are important for defibrillation requiring low electrical energy. We developed an optical mapping system that measures action potentials and controls the timings and sites of electrical stimulus to verify the effectiveness of electrical stimulation in the excitable gaps. In this paper, the time delay of feedback algorithms with our optical mapping system was evaluated and the feedback stimulation protocols were operated using isolated rabbit hearts. We optically mapped electrical activity from a surface of Langendorff-perfused rabbit hearts stained with a voltage sensitive dye using high-speed video cameras. Acquiring image data triggered a timing pulse after 5.5ms using LED. In the experiment using isolated rabbit hearts, the timing delay was 10.2 ms. The velocity and direction of wave propagation was calculated in real-time using two reference points on a field of view. The two electrical stimulating points was selected by the action potentials on electrical stimulation points. The electrical shock was delivered on the point that was triggered earlier than the other point.