AI Article Synopsis
- The study investigates the differences in electrical signals (electrograms) between the outer (epicardial) and inner (endocardial) layers of the heart during normal rhythm to better understand their roles in atrial arrhythmias.
- Researchers recorded and analyzed electrograms from 26 patients and found that the upper part of the right atrium often exhibited delayed electrical activation, indicating an occurrence of endo-epicardial asynchrony (EEA) and increased fractionation.
- The results suggest that while most electrogram fractionation is linked to remote activation rather than EEA, local differences in electrograms are significant and could play a larger role during arrhythmic events.
Article Abstract
Background: Endo-epicardial asynchrony (EEA) and the interplay between the endocardial and epicardial layers could be important in the pathophysiology of atrial arrhythmias. The morphologic differences between epicardial and endocardial atrial electrograms have not yet been described, and electrogram morphology may hold information about the presence of EEA.
Objective: The purpose of this study was to directly compare epicardial to endocardial unipolar electrogram morphology during sinus rhythm (SR) and to evaluate whether EEA contributes to electrogram fractionation by correlating fractionation to spatial activation patterns.
Methods: In 26 patients undergoing cardiac surgery, unipolar electrograms were simultaneously recorded from the epicardium and endocardium at the inferior, middle, and superior right atrial (RA) free wall during SR. Potentials were analyzed for epi-endocardial differences in local activation time, voltage, RS ratio, and fractionation. The surrounding and opposite electrograms of fractionated deflections were evaluated for corresponding local activation times in order to determine whether fractionation originated from EEA.
Results: The superior RA was predisposed to delayed activation, EEA, and fractionation. Both epicardial and endocardial electrograms demonstrated an S-predominance. Fractionation was mostly similar between the 2 sides; however, incidentally deflections up to 4 mV on 1 side could be absent on the other side. Remote activation was responsible for most fractionated deflections (95%) in SR, of which 4% could be attributed to EEA.
Conclusion: Local epi-endocardial differences in electrogram fractionation occur occasionally during SR but will likely increase during arrhythmias due to increasing EEA and (functional) conduction disorders. Electrogram fractionation can originate from EEA, and this study demonstrated that unipolar electrogram fractionation can potentially identify EEA.
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| http://dx.doi.org/10.1016/j.hrthm.2018.02.020 | DOI Listing |
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