System identification of atrial activation during chronic atrial fibrillation in man

To clarify the mechanisms maintaining chronic atrial fibrillation (CAF), a method for system identification of activation patterns of the atria during sinus rhythm (SR), artificial atrial pacing and atrial fibrillation, was developed. Data were obtained as repeated recordings of 8 sec in 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 SR and during artificial pacing and 16 patients with CAF. The realization theory was applied to fit the multivariate electrograms corresponding to individual beats during SR and type-I activations during AF, respectively. It was concluded that the local electrogram is a predictable signal during SR, artificial pacing, as well as during type-I atrial activation, and the proposed method may be used for further investigations concerning the deterministic and predictive nature of atrial activation during atrial fibrillation.