In isolated sheep hearts, accelerating atrial fibrillation increased dominant frequency domains (R=0.81, P<0.0001), and the left atrium was faster and more organized than the right atrium (P<0.00001).
In a sheep heart model, atrial fibrillation is characterized by multiple domains with distinct dominant frequencies, with the left atrium being faster and more organized than the right atrium, suggesting localized sources.
p-value: p=<0.0001
INTRODUCTION: Atrial fibrillation (AF) is characterized by complex wave propagation, yet periodic excitation suggesting a high degree of organization may be revealed during sustained AF. We provide a systematic quantification of the spatial distribution of dominant frequencies (DFs) of local excitation on the epicardium of the right atrial (RA) free wall and left atrial (LA) appendage of the isolated sheep heart during AF. The data reveal, for the first time, hidden organization, independent of the activation sequences or nature of electrograms. METHODS AND RESULTS: In 13 Langendorff-perfused sheep hearts, AF was induced in presence of 0.1 to 0.6 microM acetylcholine. Video movies (potentiometric dye di-4-ANEPPS) of the RA and LA (>30,000 and >20,000 pixels, respectively) were obtained at 120 frames/sec and a biatrial electrogram was recorded. Spectral analyses were performed on movies with DF maps constructed. During AF, the activity formed stable discrete domains with uniform DFs within each domain. Acceleration of AF increased the number of domains (R = 0.81, P < 0.0001) and the DF variance (R = 0.63, P < 0.001), indicating a decrease in organization. Also, the LA was faster and more homogeneous, with smaller number of DF domains, compared to the RA (P < 0.00001). CONCLUSION: In this model, AF is characterized by multiple domains with distinct DFs on the atrial epicardium. The decrease in domain area with increased rate suggests that AF results from high-frequency impulses that undergo spectral transformations. The LA is generally faster and more organized than the RA, suggesting that the sources for the impulses are localized to the LA.
Berenfeld et al. (Tue,) conducted a other in Atrial fibrillation (n=13). Acetylcholine was evaluated on Spatial distribution of dominant frequencies (DFs) of local excitation (p=<0.0001). In isolated sheep hearts, accelerating atrial fibrillation increased dominant frequency domains (R=0.81, P<0.0001), and the left atrium was faster and more organized than the right atrium (P<0.00001).