Figure 1.
A: Simulated episode of chronic AF in a 3D model of human atria. A local activation time map was constructed as an alternative method for detecting rotors. A pseudo-EGM signal was calculated from the 3D model. ApEn was calculated in pseudo-EGM signals recorded over the whole atrial surface. ApEn maps were constructed in order to observe the relation between ApEn values and rotor locations. B: Examples of EGM signals of DB-CZ-DE. Representatives from the four levels of complexity proposed for the purposes of the study are shown from C0 to C3. These signals were used for ApEn parameter optimization.
Figure 2.
Comparison between tools for rotor mapping.
A. Action potential wavefront delimited by contour lines over the 3D Human Atria Model extracted from the interval between 1 s and 2 s of simulation. The spinning wavefronts around one point define stable rotors R1 and R2. Line block B1 can be seen at the right inferior pulmonary vein. B. Dynamic ApEn map calculated using standard parameters and unipolar EGM. C. Dynamic ApEn map calculated from the optimized parameters obtained in our work, using unipolar EGM. D. Shannon entropy map, using unipolar EGM. Note that map C shows better sensitivity for localizing rotor tips. E. Dynamic ApEn map calculated from optimized parameters using bipolar EGM with horizontal and vertical orientation. The region corresponds to the vicinity of rotor R1. F. ShEn map calculated using the bipolar EGM obtained from the vicinity of rotor R1.
Figure 3.
Localization of stable rotors.
A: Results of the optimization procedure. Boxplots of ApEn normalized values using optimized parameters: (left) and
(right). The Spearman correlation coefficient calculated over DB-CZ-GE for each boxplot is shown. B: Activation isochronic maps corresponding to R1 (below) and R2 (top). The rotor tip is indicated where the colors converge. C: EGM generated by the model in the areas of stable rotors and the block for the time interval between 2 s and 3 s. EGM corresponding to the R1, R2, B1 and plane activation wavefront areas. D: Bipolar EGM corresponding to R1 and plane activation wavefront area. ApEn values for each EGM are shown.
Table 1.
Spatial rotor localization.
Figure 4.
The left and centre snapshots in A, B and C show the evolution of the action potential at three time instants. Meandering rotational activity is present in A and C. The snapshot on the right corresponds to the dynamic ApEn(3,0.30,500) maps. High ApEn values (red color) correspond to the presence of a meandering rotor. EGM is also shown. The star marks the 500-point interval corresponding to the evolution of the action potential. Fragmentation is generated in the presence of a rotor (A and C).