T and U waves

T waves represent ventricular repolarisation. They occur after the QRS complex. T waves are normally concordant (in the same direction) with the QRS complex, which means that in most leads they are usually upright except for in leads aVR and V1. Normal T wave height is <5mm (limb leads) or <15mm (chest leads).

U waves, if present, occur just after the T wave.

T wave changes have many possible causes, including ischemia / infarction, hypertrophy, pericarditis, myocarditis, raised intracranial pressure and medication effects.