Simultaneous Endo‐Epicardial Mapping of the Human Right Atrium: Unraveling Atrial Excitation

Figures

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  Figure 1. Simultaneous endo‐epicardial mapping of the right atrium. A, Two spatulas with 128‐electrode arrays (Ø electrode=0.4 mm, interelectrode distance=2 mm) are fixed together, 1 spatula is introduced into the right atrium through the incision for venous cannulation and one spatula is positioned on the opposite epicardial surface. Unipolar electrogram recordings are recorded at 3 mapping locations: (1) the superior caval vein (superior), (2) the inferior caval vein (inferior) and in between, (3) the terminal crest (mid). B, In the mapping clamp with endo‐ and epicardial electrode arrays, exact opposite electrodes are marked with yellow or red dots. The surrounding 8 electrodes are marked with black or blue squares. These electrodes are enlarged in C. C, The local activation times of direct opposite and its 8 surrounding electrodes are shown. Differences in local activation time between the reference electrode and the 9 opposite electrodes are calculated for the endo‐ and epicardium. Endo‐epicardial asynchrony was defined as a median time delay ≥15 ms. D, The arrows in the activation maps of the epi‐ and endocardium indicate the main direction of the propagating wavefronts. The…

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  Figure 2. Spatial distribution of atrial conduction disorders. Upper panel: Amount of CB for all endo‐ and epicardial mapping locations separately. The highest amount of CB at the endo‐ and epicardium was, respectively, 21.6% and 19.2%. No CB in either the endo‐ or epicardium occurred in, respectively, 17.2% and 24.1% of all patients. Lower panel: Amount of CB in the endo‐ and epicardial plane for each mapping location separately. The endocardium had significant more CB at each mapping location. CB indicates conduction block; and IQR, interquartile range.

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  Figure 3. Endo‐epicardial activation patterns. Examples of color coded activation maps demonstrating differences in activation between the endo‐ and epicardium including differences in local electrograms. The arrows display that the main wave trajectories and local activation times are depicted near the head and tail. Thick black lines indicate lines of conduction block. The endo‐epicardial asynchrony map (delay ≥15 ms), shows the time delay assessed at every coupled recording site. CB indicates conduction block; EEA, endo‐epicardial asynchrony; and SR, sinus rhythm.

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  Figure 4. Characteristics of atrial conduction disorders. Upper panel: Distribution of all conduction times measured at the 3 mapping locations. Of all 598.808 conduction times, only 3% (n=17.965) was ≥12 ms (cut‐off value for CB). The maximal conduction time between 2 neighboring electrodes measured in our population was 86 ms. Lower panel: Distribution of maximal conduction times, indicating the severity of conduction block, for each mapping location separately. Conduction block was most severe at the superior right atrial location (28 ms [IQR, 21–40.5], P<0.001). CB indicates conduction block; and CT, conduction time.

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  Figure 5. Prevalence and degree of endo‐epicardial asynchrony. Left panel: Relative distribution of all endo‐epicardial delays (n=161 650) of all local mapping sites, ranked according to degree of endo‐epicardial delay; 5% of all measurements were above the cut‐off value of 15 ms. Right panel: The pie chart shows the percentage of all locations with endo‐epicardial asynchrony in the entire study population. EEA indicates endo‐epicardial asynchrony.