Figure 3. Consecutive focal discharges with Ca_i prefluorescence at the onset of ventricular fibrillation.

A, shows the mapped region. B, shows dominant frequency map during ventricular fibrillation. C, shows an example of optical recording. D, shows the rise of Ca_i (orange) preceding the elevation of V_m in beats 5, 6, 7 and 10 (downward blue arrows) at site labelled a during the onset of ventricular fibrillation. E, shows isochronal maps of beats 2–7 and beat 10, which included the paced beat before ventricular fibrillation (beat 2) and beats during the development of ventricular fibrillation. These isochronal maps were drawn based on optical recordings of V_m. White arrows indicate the direction of wavefront propagation (beats 2–4) or focal discharges (beats 5–7 and 10) from the peri-infarct zone. F, shows Ca_i and V_m maps that demonstrated Ca_i prefluorescence in beats 2–4 at onset of ventricular fibrillation. DF, dominant frequency; OM, obtuse marginal branch of left circumflex artery; LAD, left anterior descending artery.