T wave

T wave Overview

The T wave is the positive deflection after each QRS complex. It represents ventricular repolarisation.

ECG basics: waves, segments and intervals LITFL ECG library

Normal T wave characteristics
  • Upright in all leads except aVR and V1
  • Amplitude < 5mm in limb leads, < 10mm in precordial leads (10mm males, 8mm females)
  • Duration relates to QT interval

T wave abnormalities

  • Peaked T waves
  • Hyperacute T waves
  • Inverted T waves
  • Biphasic T waves
  • ‘Camel Hump’ T waves
  • Flattened T waves

Peaked T waves

ECG Peaked T waves hyperkalemia
Tall, narrow, symmetrically peaked T-waves are characteristically seen in hyperkalaemia

Hyperacute T waves (HATW)

Broad, asymmetrically peaked or ‘hyperacute’ T-waves (HATW) are seen in the early stages of ST-elevation MI (STEMI), and often precede the appearance of ST elevation and Q waves. Particular attention should be paid to their size in relation to the preceding QRS complex, as HATW may appear ‘normal’ in size if the preceding QRS complex is of a small amplitude.

They are also seen with Prinzmetal angina.

Hyperacute T waves due to anterior STEMI
Prinzmetal angina
Loss of precordial T-wave balance

Loss of precordial T-wave balance occurs when the upright T wave is larger than that in V6. This is a type of hyperacute T wave.

  • The normal T wave in V1 is inverted. An upright T wave in V1 is considered abnormal — especially if it is tall (TTV1), and especially if it is new (NTTV1).
  • This finding indicates a high likelihood of coronary artery disease, and when new implies acute ischemia

Inverted T waves

Inverted T waves are seen in the following conditions:

  • Normal finding in children
  • Persistent juvenile T wave pattern
  • Myocardial ischaemia and infarction (including Wellens Syndrome)
  • Bundle branch block
  • Ventricular hypertrophy (‘strain’ patterns)
  • Pulmonary embolism
  • Hypertrophic cardiomyopathy
  • Raised intracranial pressure

** T wave inversion in lead III is a normal variant. New T-wave inversion (compared with prior ECGs) is always abnormal. Pathological T wave inversion is usually symmetrical and deep (>3mm).


Paediatric T waves

Paediatric T waves Normal T waves 2 year old boy
Inverted T-waves in the right precordial leads (V1-3) are a normal finding in children, representing the dominance of right ventricular forces

Persistent Juvenile T-wave Pattern

Juvenile-T-wave-inversion Persistent Juvenile T-wave Pattern
  • T-wave inversions in the right precordial leads may persist into adulthood and are most commonly seen in young Afro-Caribbean women
  • Persistent juvenile T-waves are asymmetric, shallow (<3mm) and usually limited to leads V1-3

Myocardial Ischaemia and Infarction

T-wave inversions due to myocardial ischaemia or infarction occur in contiguous leads based on the anatomical location of the area of ischaemia/infarction:

  • Inferior = II, III, aVF
  • Lateral = I, aVL, V5-6
  • Anterior = V2-6

NOTE:

  • Dynamic T-wave inversions are seen with acute myocardial ischaemia
  • Fixed T-wave inversions are seen following infarction, usually in association with pathological Q waves
Inferior T wave inversion due to acute ischaemia
Inferior T wave inversion due to acute ischaemia

Inferior T wave inversion with Q waves
Inferior T wave inversion with Q waves – prior myocardial infarction

Lateral; leads T wave inversion acute ischaemia
T wave inversion in the lateral leads due to acute ischaemia

Anterior T wave inversion with Q waves
Anterior T wave inversion with Q waves due to recent MI

Bundle Branch Block

In bundle branch block, T-wave inversion is an expected finding, even in the absence of ischaemia:

  • Appropriate discordance refers to the fact that abnormal depolarisation (such as in bundle branch block) should be followed by abnormal repolarisation, which appears discordant to the preceding QRS complex in the form of ST-depression and T-wave inversion
Left Bundle Branch Block
Left bundle branch block with T-wave inversion

Right Bundle Branch Block (RBBB)
Right bundle branch block with T-wave inversion

Ventricular Hypertrophy

Left Ventricular Hypertrophy (LVH)
Left ventricular hypertrophy with T-wave inversion
  • Left ventricular hypertrophy (LVH) produces T-wave inversion in the lateral leads I, aVL, V5-6 (left ventricular ‘strain’ pattern), with a similar morphology to that seen in LBBB

Right Ventricular Hypertrophy (RVH)
Right ventricular hypertrophy with T-wave inversion
  • Right ventricular hypertrophy produces T-wave inversion in the right precordial leads V1-3 (right ventricular ‘strain’ pattern) and also the inferior leads (II, III, aVF)

Pulmonary Embolism
  • Acute right heart strain (e.g. secondary to massive pulmonary embolism) produces a similar pattern to RVH
  • T-wave inversions in the right precordial (V1-3) and inferior (II, III, aVF) leads
massive pulmonary embolism ECG T wave inversion

Acute massive PE with s! Q3 T3 RBBB TWI V1-3

SI QIII TIII
  • Pulmonary embolism may also produce T-wave inversion in lead III as part of the SI QIII TIII pattern
  • S wave in lead I, Q wave in lead III, T-wave inversion in lead III
SI QIII TIII pattern in acute PE
Acute massive PE with SQIII TIII RBBB TWI V1-3

Hypertrophic Cardiomyopathy (HCM)
Hypertrophic Cardiomyopathy (HCM)

Raised intracranial pressure (ICP)
ECG TWI Raised intracranial pressure (ICP) SAH
  • Events causing a sudden rise in intracranial pressure (e.g. subarachnoid haemorrhage) produce widespread deep T-wave inversions with a bizarre morphology

Biphasic T waves

There are two main causes of biphasic T waves:

The two waves go in opposite directions:

Biphasic T waves due to ischaemia – T waves go UP then DOWN

Biphasic T waves due to ischaemia

Biphasic T waves due to Hypokalaemia – T waves go DOWN then UP

Biphasic T waves due to hypokalaemia

Wellens Syndrome

Wellens syndrome is a pattern of inverted or biphasic T waves in V2-3 (in patients presenting with/following ischaemic sounding chest pain) that is highly specific for critical stenosis of the left anterior descending artery.

There are two patterns of T-wave abnormality in Wellens syndrome:

  • Type A = Biphasic T waves with the initial deflection positive and the terminal deflection negative (25% of cases)
  • Type B = T-waves are deeply and symmetrically inverted (75% of cases)

Note: The T waves evolve over time from a Type A to a Type B pattern

Wellens Type A
Wellens Type B

‘Camel hump’ T waves

Camel hump’ T waves is a term used by Amal Mattu to describe T-waves that have a double peak. There are two causes for camel hump T waves:

  • Prominent U waves fused to the end of the T wave, as seen in severe hypokalaemia
  • Hidden P waves embedded in the T wave, as seen in sinus tachycardia and various types of heart block
Prominent U waves due to severe hypokalaemia
Prominent U waves due to severe hypokalaemia

Hidden P waves in sinus tachycardia
Hidden P waves in sinus tachycardia

Hidden P waves in marked 1st degree heart block
Hidden P waves in marked 1st degree heart block

Hidden P waves in 2nd degree
Hidden P waves in 2nd degree heart block with 2:1 conduction

Flattened T waves

Flattened T waves are a non-specific finding, but may represent

  • Ischaemia (if dynamic or in contiguous leads) or
  • Electrolyte abnormality, e.g. hypokalaemia (if generalised)

Ischaemia

Dynamic T-wave flattening due to anterior ischaemia (above). T waves return to normal once the ischaemia resolves (below).

Dynamic T wave flattening due to anterior ischaemia
Dynamic T wave flattening due to anterior ischaemia

T waves return to normal as ischaemia resolves
T waves return to normal as ischaemia resolves

Hypokalaemia

Note global T-wave flattening in hypokalaemia associated with prominent U waves in the anterior leads (V2 and V3).

T-wave flattening in hypokalaemia


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Emergency Physician in Prehospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education | ECG Library |

MBBS (UWA) CCPU Emergency Medicine Advanced Trainee based in Melbourne, Australia. Co-author of the LITFL ECG Library. Likes Ultrasound, Echo, ECGs, and anything and everything with caffeine. Part of the 2021 ANZCEN Clinician Educator Incubator Programme | @rob_buttner | ECG Library |

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