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Figure 1 The measurement of QT end and T-wave peak to T-wave end (TPE) intervals as well as the T2/T1-wave amplitude ratio in cases with bifid T waves. Vertical lines show the peak and the end of the T wave; see text for details. In the top panel, with an interpeak difference of 0.08 s, the second peak is a part of the T-wave. In the middle panel, with an interpeak difference of 0.2 s, the second peak is a U wave. In the bottom panel the interpeak difference is 0.18 s, but because the second peak is higher it is interpreted as a T2-wave with a T2/T1-wave amplitude ratio of 3.7.