Figure 1  .

Representative example of pause dependent torsade de pointes. The R-R intervals (shown in milliseconds) gradually increase due to sinus arrhythmia until a sinus cycle of 790 ms is followed by the first premature depolarisation. This extrasystole generates a longer pause (a postextrasystolic pause of 960 ms), which is followed by a sinus complex with postextrasystolic U wave augmentation (arrow) and a new premature depolarisation. The long-short sequence is perpetuated, leading to longer and faster runs of torsade de pointes. Fortuitously, the longest run is followed by a relatively short sinus cycle (arrowhead) and the vicious cycle (long-short sequence) terminates.