Deterministic patterns and coupling of bipolar recordings from the right atrium.

The presence of organization of atrial activation processes during atrial fibrillation has been investigated to assess whether the activation sequences are wholly random or are governed by deterministic mechanisms. We performed a linear analysis based on the cross correlation function and a non linear analysis based on two algorithms. The first one detects and qualifies recurrent patterns of the coupling between atrial period time series by means of the recurrence plot quantification approach; the second one estimates the non linear coupling between activation sequences in two sites following a multivariate embedding approach. The detection of spatio-temporal recurrent patterns and of non linear coupling together with the surrogate data results indicate that during atrial fibrillation a certain degree of local organization exists, likely caused by deterministic mechanisms of activation.