Key result
In a canine model of atrial fibrillation, signals in the dominant area just before drug-induced termination had lower frequencies and longer cycle lengths compared with other areas (P<0.05).
A dominant area near the SA node with lower frequencies and longer cycle lengths may play an important role in drug-induced AF termination in a canine model.
Hypothesis-generating for dominant frequency sites in AF termination; leaves open clinical translation from this canine model.
The coherence mapping was used in frequency analysis of atrial fibrillation (AF). Unipolar electrograms were recorded at AF and during infusion of antiarrhythmic drug, using a 120-electrode array (electrode spacing is 3 mm) placed on the right atrial free wall of canine. We used magnitude-squared coherence in frequency (MSCF) maps to show the frequency distribution during AF. The spectra were limited to 2-15 Hz for AF signals. We chose each site as a reference and established its MSC spectra with other sites in the array. Dominant frequency (DF) was defined by maximum power of spectrum from reference. MSC spectrum was calculated for every point in the array relative to the reference site. If the MSC value of DF is greater than or equal to 0.5, the frequency at this site is set to DF, otherwise it is set to zero. The majority of these values was assigned as the DF of that position. The spatial distribution of DFs was presented as a map, MSCF map. The dominant area (DA) was chosen from the isochronal maps. We developed the MSCF maps for four episodes: (1) normal sinus rhythm: (2) AF without drug infusion: (3) just before AF termination by drug infusion: (4) sinus rhythm following termination. The results show that MSCF map in DA just before AF termination has a uniform pattern. The signals in DA have lower frequencies and longer cycle lengths compared with those in other areas (P < 0.05). In conclusion, this mapping study of the epicardial surface during induced atrial fibrillation in canine right atrial wall has demonstrated that a dominant area near SA node may have an important role for drug-induced AF termination.
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Tso et al. (2003) studied Atrial fibrillation. Antiarrhythmic drug infusion vs. AF without drug infusion was evaluated on Frequency and cycle length in the dominant area just before AF termination (p=<0.05). In a canine model of atrial fibrillation, signals in the dominant area just before drug-induced termination had lower frequencies and longer cycle lengths compared with other areas (P<0.05).
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