ECG Basics
 

The T Wave

 
 
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Overview

  • The T wave on an ECG trace is indicative of ventricular repolarisation.
    • Look For

    • A deflection following the QRS complex that is normally asymmetrical, with a slow upslope and a rapid downslope. Usually positive, though negative T waves are normal in aVR and V1.
    •  

T Wave Flattening

    • Look For

    • Flat T waves with amplitude between +1mm to -1mm.
    • Causes of T Wave Flattening

    • Myocardial ischaemia
    • Hypokalaemia
    • Example

    • ST depression, flattened T waves and prolonged QT interval associated with hypokalaemia:
    • T Wave Flattening
       

T Wave Inversion

    • Look For

    • Negative T waves with amplitude >1mm.
    • T Wave Inversion
       
    • Causes of T Wave Inversion

    • Myocardial ischaemia / infarctionNarrow, symmetric, ‘coved’ T wave inversion
    • Physiological in children
    • Pulmonary embolism
    • Myocarditis
    • Pericarditis
    • Bundle branch block
    • Left ventricular hypertrophy
    • Hypertrophic cardiomyopathy
    • Stroke

Tall T Waves

    • Look For

    • T wave prominence. Note whether the T waves are symmetrical or asymmetrical.
    • Causes of Tall T Waves

    • Hyperkalaemia
    • Benign early repolarisation
    • Myocardial infarction
    • Interpretation

    • Narrow, symmetrical ‘tented’ T waves - suggestive of hyperkalaemia
    • Tall T waves with concave ST elevation in the precordial leads - suggestive of benign early repolarisation
    • Prominent, symmetrical and pointed (‘hyperacute’) T waves - suggestive of myocardial infarction
    • Example

    • “Tented” T waves associated with mild hyperkalaemia:
    • Tall T Waves
       
 
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