Lesson 6 of 21 · Waves & Intervals

The T Wave

The T wave is ventricular repolarization and the most sensitive (and least specific) part of the EKG. Ischemia, electrolytes, drugs, and conduction problems all change it.

01Normal T wave

Same direction as the QRS in most leads (concordant)
Upright in I, II, V3–V6; inverted in aVR
May be inverted in III, aVF, and V1 normally
Asymmetric: slow upstroke, faster downstroke

02Abnormal T waves

Peaked, narrow-based, symmetric T waves: hyperkalemia.

Broad, bulky hyperacute T waves: the earliest sign of STEMI.

Deep symmetric T inversion in V2 (Wellens type B): critical proximal LAD stenosis.

Clinical pearl. Hyperkalemia T waves are tall and narrow ('tented'); hyperacute ischemic T waves are tall and broad ('bulky').

03Secondary T-wave changes

When depolarization is abnormal (BBB, LVH, paced, WPW), repolarization is abnormal too. The T points opposite the main QRS deflection (discordant). This is expected and not ischemia by itself.

Key takeaways

Normal T follows the QRS direction
Tall + narrow = hyperK; tall + broad = hyperacute
Discordant T in BBB/LVH is expected