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 as-sociated with arrhythmias. In this study, we aimed to characterize atrial ar-rhythmia through frequency biomarkers obtained from high density panoramic optical mapping in Langendorff perfused rabbit hearts.
Methodology: 8 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 (4 to 12 Hz) using 4-second-long windows (spectral resolution was 0.05 Hz). Atrio-ventricular node ablation was performed to reduce ventricu-lar influence. We used 11 biomarkers extracted from the DF maps to study the atrial arrhythmias.
Results: The visual analysis of the 3D DF mapping in those across the atrial 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), atrial tachycardia (AT), atrial flutter (AF) and atrial fibrillation (AF) were, respectively: 2.9±0,0 Hz (99,6%, 1), 6.5±0,2 (78,8%, 2), 8.0±0,0 (94,77%, 1) and 7.5±0,1 Hz (35,51%, 4). The mean OI values decrease since from organized lower and higher frequency of activation to disorganized high frequency of activation, spanning from 0.93 during SR, to 0,61 (AT) and 0,71 (AFL), and reducing to 0.28 during AF.