Correlation Dimension as a Measure of the Atrial Fibrillation Capture during Atrial Septal Pacing
In the present model-based study, the correlation dimension (D2) was used as a measure of the effectiveness of atrial septal pacing during atrial fibrillation (AF). From ongoing simulated atrial fibrillation, instantaneous transmembrane potential maps were used as initial conditions for a rapid pacing from the septum area at pacing cycle length (PCL) expressed as a percentage of the AF cycle length. During the pacing, transmembrane potentials time series at four sites on the right/left atrial (RA/LA) walls were recorded and D2 was separately computed. The results indicated a lower D2 value (2.17±0.42) for PCL in the range 85-95% of AFCL compared to D2 (3.53±0.31) obtained for the other PCL values. Moreover, for PCL in the range 85-95% of AFCL the results indicated a better capture in the RA than in the LA (p<0.005). The overall results suggest that D2 can discriminate between different levels of atrial activity organization during AF pacing therapies. This makes possible the assessment of suitable PCL values leading to appropriate AF capture.