Key result
Computational optical flow approach locates simulated AF mechanisms with 100% accuracy.
Why the study?
AF has different underlying activation mechanisms, including functional rotors and ectopic foci, requiring methods for locating them in potential maps.
A computational method using Farneback optical flow and curl/divergence operators can locate functional rotors and ectopic foci in mathematical phantoms of atrial fibrillation, though accuracy depends on spatial resolution.
Promising for simulated AF rotor detection; leaves open clinical translation and requires in vivo validation.
Atrial Fibrillation (AF) is the most common supraventricular arrhythmia and has different underlying activation mechanism, including functional rotors (FR) and ectopic foci (EF).In this work we propose an approach for locating FR and EF in potential maps, which were tested with mathematical phantoms.12 phantoms were created (128x128 array, 4 s, Fs 500 Hz), simulating the motion of: FR (4 maps), EF (4 maps) and superpositions of these (4 maps).These were downsampled to different grids from 16x16 to 8x8, simulating electrode acquisition.Noise (SNR from 2 to 60) was added.To locate the mechanism, the signals were filtered and interpolated.Farneback optical flow was applied to compute the motion vector field (MVF).The MVF was normalized and its temporal average was calculated.Finally, we computed curl and divergence, by using a x and y oriented 11 11 Sobel filter as a estimation of the of the partial derivatives.The location of extrema in the curl and divergence maps were used for locating FR and EF respectively.Method robustness was tested by comparing the algorithm performance on different grid sizes and SNR.The mechanism was considered to be detected accurately if the position was within a normalized error of 5% from its respective phantom location.The results showed that our approach was able to locate both mechanisms, but revealed a dependency on spatial resolution.
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Oliveira et al. (2022) studied Atrial Fibrillation (simulated) (n=12). Computational method using Farneback optical flow, curl, and divergence operators vs. Different grid sizes and signal-to-noise ratios was evaluated on Location accuracy (normalized error < 5% from phantom location). A computational approach using Farneback optical flow and vector field operators successfully located simulated atrial fibrillation mechanisms, achieving 100% accuracy at a 16x16 grid resolution.
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