System identification of atrial activation during chronic atrial fibrillation in man

To further clarify the mechanisms maintaining chronic atrial fibrillation (CAF), a method for system identification of activation patterns of the atria was developed. Data were obtained as repeated recordings of 8 s duration, each of 56 atrial bipolar electrograms, simultaneously acquired during open-heart surgery at multiple sites in the right atrial free wall in 12 patients with stable sinus rhythm (SR) and during artificial pacing and 16 patients with chronic atrial fibrillation (AF). Realization theory was applied to fit and reproduce the multivariate electrograms corresponding to individual beats during SR and type I activations during AF, respectively-in all cases and for all subjects tested with good accuracy. The local electrogram was a predictable signal in all cases tested and the proposed method may be used for further investigations concerning the deterministic and predictive nature of atrial activation during atrial fibrillation.