OBJECTIVE: The instant of maximum slope (Tup) of the T wave in the unipolar electrogram is a well-established measure of repolarisation time (TR). Nevertheless, recent observations on positive T waves have caused a renewed debate. The purpose of this study was to elucidate the mechanism that leads to positive and negative T waves and to investigate which electrogram feature best predicts TR. METHODS: We simulated propagating action potentials (AP) and electrograms with a bidomain reaction-diffusion model of the human heart including heterogeneous ion-channel properties. To explain positive T waves we compared results with those of a much simpler model, which predicts T waves from local and remote AP. RESULTS: Repolarisation time was defined as the instant of steepest downstroke of the AP. T wave polarity was mostly determined by TR. Positive T waves occurred at early-repolarising sites. Correlation between Tup and TR was >0.99, in both negative and positive T waves. T wave area and peak value also correlated highly with TR. CONCLUSION: The polarity of the T wave is primarily determined by TR. Positive T waves occur at early-repolarising sites. Local TR is best estimated by Tup, also in positive T waves.
OBJECTIVE: The instant of maximum slope (Tup) of the T wave in the unipolar electrogram is a well-established measure of repolarisation time (TR). Nevertheless, recent observations on positive T waves have caused a renewed debate. The purpose of this study was to elucidate the mechanism that leads to positive and negative T waves and to investigate which electrogram feature best predicts TR. METHODS: We simulated propagating action potentials (AP) and electrograms with a bidomain reaction-diffusion model of the human heart including heterogeneous ion-channel properties. To explain positive T waves we compared results with those of a much simpler model, which predicts T waves from local and remote AP. RESULTS: Repolarisation time was defined as the instant of steepest downstroke of the AP. T wave polarity was mostly determined by TR. Positive T waves occurred at early-repolarising sites. Correlation between Tup and TR was >0.99, in both negative and positive T waves. T wave area and peak value also correlated highly with TR. CONCLUSION: The polarity of the T wave is primarily determined by TR. Positive T waves occur at early-repolarising sites. Local TR is best estimated by Tup, also in positive T waves.
Authors: Malcolm C Finlay; Akbar K Ahmed; Alan Sugrue; Justine Bhar-Amato; Giovanni Quarta; Antonis Pantazis; Edward J Ciaccio; Petros Syrris; Srijita Sen-Chowdhry; Ron Ben-Simon; Anthony W Chow; Martin D Lowe; Oliver R Segal; William J McKenna; Pier D Lambiase Journal: PLoS One Date: 2014-07-11 Impact factor: 3.240