Introduction: Cardiac arrhythmias mechanism can be challenging to diagnose hampering effective treatment. A comprehensive understanding of the intricate dynamics of cardiac electrical activity is essential to unravel the complexities associated with arrhythmias. In this study, we aimed to characterize arrhythmias through frequency biomarkers obtained from high density panoramic optical mapping in Langendorff perfused rabbit hearts.
Methodology: 6 New Zealand White rabbits (3.44±0.36 kg) were employed in the study. Isolated rabbit hearts were extracted and perfused by Krebs solution through a Langendorff perfused system. Panoramic optical map-ping (dye Di-4-ANBDQPQ, 3 cameras HB-1800-S, Emergent technologies, 6 deep-red 650 nm LEDs, 500 FPS, 1600 x 1000 pixels) allows high density mapping of the entire heart during episodes of atrial arrhythmias, induced electrically, by a S1-S2 protocol, after infusion of carbachol (1µM). Spec-tral analysis allowed determination of DF at each pixel. DF was defined as the frequency with highest amplitude within the physiological relevant range (1 to 12 Hz) using 4-second-long windows (spectral resolution was 0.05 Hz). We used 12 biomarkers extracted from the DF maps to study cardiac arrhythmias.
Results: The visual analysis of the 3D DF mapping in those across the rhythms showed that DF evolves its size and position in time. The HDF values (its average size and the number of HDFs) during the sinus rhythm (SR), sinus tachycardia, atrial tachycardia (AT), atrial fibrillation (AF), ventricular tachycardia (VT) and ventricular fibrillation (VF) were, respectively: 1.74 Hz (100%, 1), 4.80 Hz (100%, 1), 7.10 Hz (38.8%, 1), 7.80 Hz (63.7%, 3), 8.10 Hz (100%, 1), and 7.50 Hz (41.7%, 2). An overall, the mean OI values decrease from organized to disorganized rhythms: 0.94 (SR), 0.88 (ST), 0.45 (TA), 0.50 (AF), 0.80 (VT) and 0.50 (VF).