10.1371/journal.pone.0175087.g001 Peter R. Rijnbeek Peter R. Rijnbeek Marten E. van den Berg Marten E. van den Berg Gerard van Herpen Gerard van Herpen Henk J. Ritsema van Eck Henk J. Ritsema van Eck Jan A. Kors Jan A. Kors Example of a simulated QT-interval change. Public Library of Science 2017 QT variability STV estimates QT interval variability Background QTV measurement procedures QTV measurement techniques FSA algorithm signal length beat-to-beat QT-interval durations QTV measurement algorithm P-QRS-T ECG QTV measurement approach validation 2017-04-12 18:18:40 Figure https://plos.figshare.com/articles/figure/Example_of_a_simulated_QT-interval_change_/4870130 <p>The black line indicates the original ECG signal with the vertical line denoting the end of the T wave as determined by the MEANS program. The grey line indicates the signal with a shifted end of the T wave. The horizontal bars below the signals mark symmetric windows of 180 ms around the end of the T wave in which the signal is not deformed. The signal segment from QRS end till the start of the window is extended, whereas the signal segment from the end of the window till the onset of the next P wave is compressed.</p>