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. 2008 Jan 31;10(1):015004.
doi: 10.1088/1367-2630/10/1/015004.

Epicardial wavefronts arise from widely distributed transient sources during ventricular fibrillation in the isolated swine heart

Affiliations

Epicardial wavefronts arise from widely distributed transient sources during ventricular fibrillation in the isolated swine heart

J M Rogers et al. New J Phys. .

Abstract

It has been proposed that VF waves emanate from stable localized sources, often called "mother rotors." However, evidence for the existence of these rotors is conflicting. Using a new panoramic optical mapping system that can image nearly the entire ventricular epicardium, we recently excluded epicardial mother rotors as the drivers of Wiggers' stage II VF in the isolated swine heart. Furthermore, we were unable to find evidence that VF requires sustained intramural sources. The present study was designed to test the following hypotheses: 1. VF is driven by a specific region, and 2. Rotors that are long-lived, though not necessarily permanent, are the primary generators of VF wavefronts. Using panoramic optical mapping, we mapped VF wavefronts from 6 isolated swine hearts. Wavefronts were tracked to characterize their activation pathways and to locate their originating sources. We found that the wavefronts that participate in epicardial reentry were not confined to a compact region; rather they activated the entire epicardial surface. New wavefronts feeding into the epicardial activation pattern were generated over the majority of the epicardium and almost all of them were associated with rotors or repetitive breakthrough patterns that lasted for less than 2 s. These findings indicate that epicardial wavefronts in this model are generated by many transitory epicardial sources distributed over the entire surface of the heart.

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Figures

Figure 1
Figure 1
A simple wavefront graph. Each arrow represents a wavefront. The horizontal positions of a wavefront’s endpoints place the wavefront in time. The vertical positions are not significant. Wavefront a fragments into wavefronts b and c; wavefronts c and d collide and coalesce to form wavefront e, which later fragments into wavefronts f and g.
Figure 2
Figure 2
Geometric models used to compute ChL. A. Complete epicardial model. B. Lateral half of the model in A. C. Apical half of the model in A. These geometries contained 4326, 2387, and 2233 triangles, respectively. The ChL values were 34.04 mm, 26.61 mm, and 22.89 mm, respectively.
Figure 3
Figure 3
Independence of characteristic length on the size of the set used to compute it. The bars show characteristic length averaged over 10 trials for each set size. The error bars are standard deviations. There was no significant difference between groups (p>0.6). The ChL of the full set from which the test samples were drawn was 34.04 mm.
Figure 4
Figure 4
Wavefronts during VF. Snapshots are from the same episode and are separated by 1 s. The geometry is displayed with a Hammer map projection so that the entire epicardium is visible. The black lines in panel A indicate the approximate boundaries between the right and left ventricles. The wide colored lines are wavefronts: the perennial wavefronts are cyan, the remaining wavefronts from the dominant component are yellow, and wavefronts from other components are red. The entire 4-second episode is animated in supplemental movie S1.
Figure 5
Figure 5
Distribution of root sites (white triangles) from one VF episode. Some white triangles may have been the root site for more than one root wavefront. The geometry is displayed with a Hammer map projection. The anatomic orientation is similar to Figure 4. The normalized source site ChL is 0.96.

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