A fixed point algorithm for extracting the atrial activity in the frequency domain

In this work we present a fixed point algorithm to extract the atrial rhythm in atrial tachyarrhythmias from the surface electrocardiogram (ECG). In the frequency domain the atrial signal is characterized by a concentration of power around a main peak in the bandwidth 3–10 Hz. The proposed algorithm exploits this discriminative property of the atrial component in combination with the decoupling of the atrial and other components superposed in the ECG. It recovers only the interesting atrial rhythm in a simple, fast and reliable way using the information contained in all the leads and reducing the average computational time from 0.902 s (FastICA) to 0.023 s (the proposed method). The algorithm is applied successfully to synthetic and real data. In simulated ECGs, the correlation index obtained was 0.792. In real ECGs, the accuracy of the results was validated using spectral and temporal parameters. The average peak frequency and spectral concentration obtained were 5.354 Hz and 59.4%, respectively, and the kurtosis was 0.065.