Optical imaging of voltage and calcium in isolated hearts: Linking spatiotemporal heterogeneities and ventricular fibrillation initiation

Figures

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  Fig 1. Experimental setup used. (A) Diagram of the optical mapping system. (B) Schematic diagram of the experimental protocol. (C) Representation of APD and CaT alternans maps and signals that compose them during a spatially discordant stage: (1) a short-long pattern with positive coupling, (2) a long-short pattern with positive coupling, (3) a negative coupling and (4) a nodal line region without alternans.

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  Fig 2. Rate-dependent development of electrophysiological features obtained at different pacing cycle length in basal conditions. (A) Distribution of local CV through the trajectory of propagation over isochrones fragmented in steps of 5 ms (black). (B) Maps of APD alternans obtained between successive wavefronts. (C) Maps of CaT alternans obtained between successive propagations. (D) Recordings of optical voltage and calcium signals.

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  Fig 3. Sequence of VF induction. (A) Recordings of optical voltage and calcium signals of induction of VF, belonging to point 1 in panel B. (B) Distribution of APD and CaT alternans during two beats previous to the VF onset, the marked shaded line indicates the region with the highest alternans. (C) Sequence of isochronal maps corresponding to the traces depicted in panel A. Notice how during the second propagation (i.e. 125ms) a line of block was formed. This line of block allowed the appearance of reentrant patterns in the following isochrones and the perpetuation of the VF. A possible pathway of reentrant pattern is suggested by white arrows.

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  Fig 4. Effect of verapamil administration on alternans and CV. (A) Distribution of APD and CaT alternans maps together with the mean local CV at baseline, compared to same maps computed at the same pacing rate after administration of verapamil. (B) Normalized voltage and calcium optical signals of points A and B labeled on alternans maps.

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  Fig 5. Rate-dependent development of electrophysiological features obtained at different pacing cycle length after verapamil administration. (A) Distribution of local CV through the trajectory of propagation over isochrones fragmented in steps of 5 ms (black). (B) Maps of APD alternans obtained between successive wavefronts. (C) Maps of CaT alternans obtained between successive propagations. (D) Recordings of optical voltage and calcium signals.

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  Fig 6. Rate-dependent changes of APD, voltage and calcium alternans for the entire dataset. (A) Progression of APD (top panel), magnitude of APD alternans computed (middle panel) and magnitude of CaT alternans (bottom panel). (B) Percentage of area of APD (top panel) and CaT alternans (bottom panel) that covers the ventricular surface recorded during the application of the protocol of increasing rhythms during basal conditions and after verapamil administration. * Means p< 0.05.

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  Fig 7. Maximal and minimal CV recorded previously to the induction of VF. (A) Maximal and (B) minimal CV measured in the optical mapping with the fastest pacing rate previously to the induction of VF, both during basal conditions and after verapamil administration. * Means p< 0.01.