In vivo human sock‐mapping validation of a simple model that explains unipolar electrogram morphology in relation to conduction‐repolarization dynamics

Figures

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  Figure 1. Schematic representation of the model. UEG were recorded using a multielectrode sock measuring 240 UEGs. A, Activation (AT, circle) and repolarization times (RT, cross) were measured from the unipolar electrogram (UEG). B, For each cardiac site, a local action potential (red line) was generated by adjusting a stylized action potential to fit AT and RT measured in vivo. C, The position‐independent component (blue bold line) representing remote activity was computed as the mean of all APs (only a representative subset of the local APs is shown dashed black lines). D, The simulated UEGs, generated as a rescaled difference between the remote and local components, shows similar morphology as the corresponding recorded one shown in panel A [Color figure can be viewed at http://wileyonlinelibrary.com]

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  Figure 2. Top: UEGs recorded in one patient at sites P1–P3 showing different morphologies. Middle: Local (bold line) and remote position‐independent (blue bold line) components from the simple model. Bottom: Simulated UEGs generated as a rescaled difference between the remote and local components are similar to the recorded one (top panels). From left to right, a UEG shows QS‐, RS‐, or R‐waves when the local component precedes, intersects, or follows the remote one, respectively. Similarly, a UEG shows a positive, biphasic, or negative T‐wave when the local component precedes, intersects, or follows the remote one, respectively. The occurrence of QRS complexes and T‐waves with different morphologies depends on activation and repolarization sequences, respectively, and any combination is possible. Figures adapted from (7) [Color figure can be viewed at http://wileyonlinelibrary.com]

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  Figure 3. A, Distribution of the correlation coefficients indicating the morphological similarity between recorded and simulated UEGs. Correlations were considered within the entire signal (indicated as UEG in the figure) as well as within the QRS and the T‐wave, separately. B, Representative examples of recorded (red) and simulated (black) UEGs corresponding to correlation coefficients equal to the first (Q1), second (MED), and third (Q3) quartile. The correlation coefficients are calculated within the entire signal (left), within the QRS (middle), and the T‐wave (right), and the panels are adjusted to highlight the correlation within these intervals [Color figure can be viewed at http://wileyonlinelibrary.com]

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  Figure 4. Representative example of morphological similarity between recorded and simulated unipolar electrograms (UEG). Color maps show the area under the QRS complexes (left) and T‐waves (right) of UEGs recorded in one patient (top, anterior view on the left, inferior view on the right) and in the corresponding simulated UEGs (below). The black line on the ventricular mesh indicates the approximate location of the LAD. On the bottom, the scatterplots indicate high correlation between the recorded and simulated QRS area (left) and T‐waves (right) (correlation coefficient cc ≥ 0.91) [Color figure can be viewed at http://wileyonlinelibrary.com]

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  Figure 5. Spatial interaction between activation/repolarization dynamics and the morphology of the unipolar electrograms. A, Strong positive correlation between the area under the QRS complex of the local unipolar electrogram (UEG) and local activation (AT) measured at the same site. Gray circles and white diamonds indicate results from recorded and simulated UEGs, respectively. Bottom: examples of QRS complexes from recorded UEGs corresponding to AT equal to the 10th, 50th, and 90th percentile (white circles). B, Strong negative correlation between the area under the T‐wave of the local unipolar electrogram (UEG) and local repolarization time (RT) measured at the same site. Gray circles and white diamonds indicate results from recorded and simulated UEGs, respectively. Bottom: examples of T waves from recorded UEGs corresponding to RT equal to the 10th, 50th, and 90th percentile (white circles)