Abstract 10607: Atrial Fibrillation in Post Open Heart Surgery: Is There a Driver?
Background: Post operative atrial fibrillation (POAF) is a common complication of open heart surgery. The canine sterile pericarditis (CSP) model of AF provides an experimental counterpart to POAF. We have shown that AF in this model is frequently due to a rapid, regular, stable left atrial (LA) reentrant circuit (driver) causing fibrillatory conduction to most of the rest of the atria. The primary purpose of this study was to evaluate the characteristics of atrial electrograms (AEGs) recorded during spontaneous POAF. We hypothesized that areas of rapid, regular activity would be recorded in the LA, consistent with the presence of a driver.
Methods: Based on studies in the CSP model, AEGs were recorded from 3 pairs of epicardial wire electrodes placed on the right atrium, left side of Bachmann's bundle and postero-inferior LA at time of surgery. Up to 110 seconds of simultaneous, continuous recordings were obtained during each AF episode. Ten second periods of data were analyzed for dominant frequency (DF), and cycle lengths (CLs) were measured to obtain their mean and standard deviation (SD). The regularity at each site was assessed based on AEG morphology, DF, and the regularity index, which was defined as: (SD of CL) / (10% of the mean AEG CL). An episode was regular if AEG morphology was constant, DF correlated with the measured mean CL, and the regularity index was < 1.
Results: Twenty-two patients (70 ± 10 yrs) were prospectively enrolled. Ten patients developed AF (45%) on post operative days 1 - 6 (peak incidence days 2 - 4). Eight AF episodes (in 7/10 patients) were recorded. One or more sites of stable, regular activity occurred in 4/8 episodes (mean CL 162 ms, range 144 - 191 ms). Periods of transient regularity lasting < 2 seconds occurred in an additional 3 episodes. Only 1/8 AF episodes, which was recorded on post operative day 1, had no regularity. All episodes of regularity, both stable and transient, were present in the LA, with the mean LA CL shorter than the mean right atrial CL.
Conclusion: AEGs during spontaneous POAF demonstrated rapid and regular LA activity consistent with a driver mechanism. While regularity was not present in all AF episodes, existence of regular activity could not be excluded, as we only recorded AEGs from 3 sites.
- © 2011 by American Heart Association, Inc.