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Figure 1 Measurements of the dispersion of repolarization (DR) between the right ventricular outflow tract (RVOT) and the right ventricular apex (RVA) following an electrical shock. Simultaneous recordings of the surface electrocardiogram (ECG), the monophasic action potential (MAP) in the RVOT and the MAP in the RVA. The coupling interval (CI) is the time between the upstroke of the MAP and the shock artifact. The post-shock repolarization time (PSRT) is the time between the shock artifact and the full repolarization following the shock. Post-shock DR (PSDR) is the difference between the PSRTs in the RVOT and RVA (time between the two dashed lines). This is an example of a successful induction of ventricular fibrillation (VF) by a T wave shock. Post-shock repolarization time in the RVA is 180 ms; PSRT in the RVOT is 90 ms. PSDR is 90 ms and is followed by VF.