What does the QT interval on a normal ECG primarily represent?
Ventricular depolarisation and repolarisation
The QT interval is measured from the start of the QRS complex to the end of the T wave, so it encompasses the whole electrical systole of the ventricles — both ventricular depolarisation (QRS) and ventricular repolarisation (ST-T).
Atrial contraction/depolarisation is reflected by the P wave, atrial repolarisation is hidden within the QRS, and ventricular contraction alone is a mechanical event — not the full QT.
Hence, Ventricular depolarisation and repolarisation.
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