Key result
Rapid atrial pacing-induced sustained atrial fibrillation in pigs was associated with shorter mean effective refractory period (107 vs 142 ms; P<0.001) and greater dispersion of refractoriness.
Why the study?
What electrophysiologic characteristics of the right atrium are associated with the persistence of atrial fibrillation after its induction in a porcine model?
What electrophysiologic characteristics of the right atrium are associated with the persistence of atrial fibrillation after its induction in a porcine model?
p-value: p=<0.001
In a porcine model, the persistence of atrial fibrillation is associated with shorter effective refractory period and wavelength, as well as greater dispersion of refractoriness and electrical remodeling.
Supports atrial remodeling research in animal AF models; leaves open human electrophysiologic translation.
BACKGROUND: The electrophysiologic mechanisms of the persistence of atrial fibrillation (AF) after its initiation are not well understood. Therefore, the electrophysiologic characteristics of the right atrium were evaluated in an acute, pacing-induced model of AF in the pig in order to identify parameters associated with persistence of AF. METHODS AND RESULTS: AF was induced by rapid atrial pacing in 30 anesthetized, open-chest, juvenile pigs. Sustained (S) AF was defined as that lasting >10 minutes, nonsustained (NS) AF <10 minutes but >30 seconds, and no (N) AF <30 seconds. Activation mapping and programmed stimulation (S1S1 = 200 ms) was performed at 56 electrodes on the right atrial free wall, to determine ERP (mean and minimum), dispersion of refractoriness (ERPdisp, ELEdisp), conduction velocity (CV), wavelength, AF cycle length (mean of 10 beats), and AF cycle length/time (electrical remodeling). SAF was induced in 10 pigs, NSAF in 9, and NAF in 11. AF cycle length was shorter in SAF and/vs NS vs NAF (P <.001). Mean ERP (107 +/- 9 and/vs 122 +/- 5 vs 142 +/- 9, p <.001) and wavelength (7 +/- 1 and/vs 9 +/- 1 vs 11 +/- 1, P <.001) were shorter in SAF and/vs NSAF vs NAF. Minimum ERP was shorter in SAF and NSAF vs NAF (P <.001). CV at cycle lengths of 200 and 150 msec was not different between groups. Dispersion of ERP was greater in SAF and/vs NSAF vs NAF (8 +/- 1 and/vs 11 +/- 1 vs 19 +/- 4, P <.001). CONCLUSIONS: Persistence of AF correlated with shorter ERP and wavelength, and greater dispersion of ERP and electrical remodeling. There was no correlation with CV.
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Rahme et al. (1999) studied Atrial fibrillation (n=30). Rapid atrial pacing vs. No AF or nonsustained AF was evaluated on Mean effective refractory period (ERP) (p=<0.001). Rapid atrial pacing-induced sustained atrial fibrillation in pigs was associated with shorter mean effective refractory period (107 vs 142 ms; P<0.001) and greater dispersion of refractoriness.
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