T wave

Last reviewed 01/2018

T waves represent repolarisation of the heart, and undergo temporary or permanent change.

Normal: T waves down in V1, V2, never V3, sometimes in III and aVF (1). The T wave may be normally inverted or upright in III and in V1 (and in V2 in young people, and also in V3 in some Afro-Caribbeans).

The T wave may be lengthened or made taller by electrolyte imbalances, especially potassium. Hypokalaemia flattens the T wave and prolongs the QT interval (the duration from the Q wave to the end of the T wave) to more than 0.4 seconds.

Click here for example ECGs and further information relating to T wave changes and myocardial ischaemia

Reference:

  • Hampton J (1993).Interpreting the ECG. Medicine International, 21, 318-24.