Introduction
The U wave is a small (0.5 mm) deflection immediately following the T wave.
Etiology
The mechanism is questionable, but it is assumed:
- delayed repolarization of the ventricular septum
- delayed repolarization of some parts of the ventricles
- repolarization of Purkinje fibers
ECG features
- U wave is concordant with the T wave (has the same polarity as a T wave)
- Amplitude is approx. 0.5 - 2mm
- Best visible in V2-V3
- Is present in bradycardia
Prominent U wave
- The amplitude is> 1-2mm or > 25% T wave
- The most common causes:
- Bradycardia
- Hypokalaemia
- Uncommon causes
- Hypocalcaemia
- Hypomagnesemia
- Hypothermia
- Increased intracranial pressure
- Left ventricular hypertrophy
- Digoxin
Inverted U wave
- It is highly specific for myocardial ischemia
- It may be the first marker of acute coronary syndrome
- Causes of inverted U wave
- Myocardial ischemia
- Cardiomyopathy
- Hyperthyroidism
ECG 1 U wave in a patient with severe hypokalemia (best seen in V1-V3)
References
- Girish MP, Gupta MD, Mukhopadhyay S, Yusuf J, Sunil Roy TN, Trehan V. U wave: an important noninvasive electrocardiographic diagnostic marker. Indian Pacing Electrophysiol J. 2005 Jan 1;5(1):63-5. PMID: 16943944; PMCID: PMC1502069.
- https://www.techmed.sk/u-vlna/
- https://litfl.com/u-wave-ecg-library/
Published by
Assoc. Prof. Michal Pazderník, MD, Ph.D. FESC
Introduction
The U wave is a small (0.5 mm) deflection immediately following the T wave.
Etiology
The mechanism is questionable, but it is assumed:
- delayed repolarization of the ventricular septum
- delayed repolarization of some parts of the ventricles
- repolarization of Purkinje fibers
ECG features
- U wave is concordant with the T wave (has the same polarity as a T wave)
- Amplitude is approx. 0.5 - 2mm
- Best visible in V2-V3
- Is present in bradycardia
Prominent U wave
- The amplitude is> 1-2mm or > 25% T wave
- The most common causes:
- Bradycardia
- Hypokalaemia
- Uncommon causes
- Hypocalcaemia
- Hypomagnesemia
- Hypothermia
- Increased intracranial pressure
- Left ventricular hypertrophy
- Digoxin
Inverted U wave
- It is highly specific for myocardial ischemia
- It may be the first marker of acute coronary syndrome
- Causes of inverted U wave
- Myocardial ischemia
- Cardiomyopathy
- Hyperthyroidism
ECG 1 U wave in a patient with severe hypokalemia (best seen in V1-V3)
References
- Girish MP, Gupta MD, Mukhopadhyay S, Yusuf J, Sunil Roy TN, Trehan V. U wave: an important noninvasive electrocardiographic diagnostic marker. Indian Pacing Electrophysiol J. 2005 Jan 1;5(1):63-5. PMID: 16943944; PMCID: PMC1502069.
- https://www.techmed.sk/u-vlna/
- https://litfl.com/u-wave-ecg-library/
Published by
Assoc. Prof. Michal Pazderník, MD, Ph.D. FESC
