Directed graph mapping shows rotors maintain non-terminating and focal sources maintain self-terminating Torsade de Pointes in canine model

Figures

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  FIGURE 1. Schematic representation of the positioning of the needles (black lines) and their electrode terminals (black dots) inside one layer of the ventricular wall (gray area). Configuration 1 was used for dog 1 and configuration 2 for dogs 2–5. The whole ventricles are represented by stacking 6 of these layers on top of one another spaced 1.2 cm apart. Figure reproduced from Vandersickel et al. (2017).

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  FIGURE 2. Result of DGM analysis during one episode of TdP in dog 1. Every coloured sphere represents the location of a needle electrode (cf. configuration 1 from Figure 1) Blue arrow show loops detected by DGM. Orange arrows point to a bi-ventricular loop, green arrow to a localized re-entry. (A) Top-down view. (B) Anterior view.

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  FIGURE 3. Visual explanation of (A) core, border and noise points and (B) density reachability. This figure is reproduced from Hahsler et al. (2019) under CC-BY licence.

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  FIGURE 4. Example for reentry episode Dog 1: ST 1, taking place between 606 s and 611 s after administration of dofetilide. Each blue block represents one distinct reentry loop. In the row underneath the reentry, the start of the focal sources are indicated with red stars. Three distinct reentries were detected between 1,000 ms and 2,400 ms, with at most 2 concurrently present. One loop is present from 1,000 ms to 2,400 ms, a second reentry from 1,300 ms to 1,450 ms and the last one from 1800 ms to 2,100 ms. Following the reentry, 5 more focal beats are detected before termination of the episode.

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  FIGURE 5. For every reentry episode, the total reentry duration was split into parts, based on the number of simultaneous reentry loops present. These parts are indicated with different colours. The designations of the ST episodes are coloured green, of NT episodes in red. NT episodes reach higher numbers of simultaneous loops compared to the ST group. Average and maximum number of simultaneous loops during the episodes were significantly different between NT and ST groups.

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  FIGURE 6. The episodes from Figure 5 are added to their respective groups (NT: green, ST: red). Subsequently, the averages were calculated for each colour in Figure 5, corresponding to a certain number of simultaneous loops. This resulted in the heights of the bars.

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  FIGURE 7. Box plot of the average number of simultaneous loops in each episode. ** indicate a significant difference with p <0.01 (Mann–Whitney U test, p=˙0.003 ).

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  FIGURE 8. For each reentry episode, the percentage of time that a reentry proved to be either holo- or bi-ventricular is observed. The duration percentages of the ST (Green) and NT (Red) episodes can subsequently be compared. We can see that this type of reentry is barely present in the ST group (Green), only in 1 of the 4 episodes. In contrast to the ST group, all 9 NT episodes show presence of this type of reentry. In addition, all NT episodes developed (bi-)ventricular reentry to a higher degree that any episode in the ST group. The percentages of time during which holo- or biventricular reentry is present are significantly different between ST and NT groups (Mann–Whitney U test, p=˙0.024 ).

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  FIGURE 9. Focal source location results within one dog. (A) Heatmap, representing the ventricles of dog 1 in which 120 focal sources were discovered over 18 TdP episodes, including those that degenerated into reentry. These sources are distributed over a total of 173 electrodes. The colour of an area indicates the amount of focal sources. The Y-axis is oriented from the anterior wall (Y =0) to the posterior wall (Y =60). (B) Barchart counting all electrodes (y-axis) containing a certain amount of focal sources (x-axis). The embedded table shows the expected distribution of amount of focal sources if they would be randomly distributed.