Last update: April 2020


Definition

  Beat to beat alternating amplitudes or the configuration of the P, QRS and/or T waves.

 
QRS alternans is the most common among them.

  If P, QRS and T waves are all involved, it is called as
total alternans.



Causes of electrical alternans

  Massive pericardial effusion.

  Myocardial failure.

  Narrow QRS tachycardia (independent of the tachycardia mechanism).

  Myocardial ischemia.

  Long QT interval syndrome (congenital or acquired).

  ST segment alternans has been reported in association with the Brugada pattern.

  Gastric volvulus.



Significance of T-wave alternans

  T wave alternans is a marker of electrical instability and regional heterogeneity of repolarization.

  Patients with T wave alternans have an increased risk of cardiac events.




References

  Clin Med (Lond) 2019 Nov;19:528-529.

  Circ Arrhythm Electrophysiol. 2016 Feb;9(2):e003206. doi: 10.1161/CIRCEP.115.003206.

  Cardiovasc J Afr 2013 Mar 23;24(2):e1-3. doi: 10.5830/CVJA-2012-065.

  Am J Crit Care 2012;21:365-366.

  J Am Coll Cardiol. 1994 Jun;23(7):1541-6.

  J Am Coll Cardiol 1987;9:489-499.

  Ann Intern Med, 1974; 814: 51-54.





ECG 1. QRS
aLtE rNaNc E is seen in a patient with pericarditis and pericardial effusion.

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ECG 2. QRS alternance in a patient with pericarditis and massive pericardial effusion.

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ECG 3. This ECG is from a patient with pericardial effusion. QRS amplitude
increases and decreases : QRS alternance.

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ECG 4. The above ECG shows T wave alternans in a patient with long QT syndrome.

Pediatric cardiologist Prof. Dr. Birgul Varan has donated the above ECG to our website.

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ECG 5a. The ECG above is from a middle-aged hypertensive man and was recorded during retrosternal chest pain.
He was diagnosed as having unstable angina pectoris and coronary angiography was performed immediately after this ECG.
QRS amplitude is changing during myocardial ischemia.
Also, inferior leads and the V6 show T wave negativity, and the lead V5 shows T wave flattening.
According to Gubner criteria, this ECG is compatible with left ventricular hypertrophy.

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ECG 5b. Two hours later, ECG was recorded again. This time, the patient had no chest pain.
No angina, no QRS alternance.
T wave negativity in inferior leads persist.
Now the T wave in lead V5 is upright and the negative T wave in lead V6 has disappeared.

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ECG 5c. Next day, another ECG was recorded during angina pectoris (above).
QRS amplitude is changing again due to myocardial ischemia.
Now many leads show ST segment depression while leads V1 and aVR show ST segment elevation.

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ECG 5d. On the same day with ECG 6c, another ECG was recorded but now the patient does not have chest pain.
No ischemia, no QRS alternance.

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ECG 6a. The ECG above is from a 55 years-old man with a diagnosis of unstable angina pectoris.
It was recorded while the patient was being prepared for the coronary artery surgery.
Coronary angiography showed 2 significant stenoses in the proximal Left ANterior Descending (LAD) coronary artery.
Subtle
T wave alternans is seen in the lead V3.

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ECG 6b. After 3 hours, a new ECG showed that the T wave negativity in precordial leads became more diffuse.
T wave alternans is more clear now.

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ECG 6c. Precordial rhythm strip of the same patient at a calibration of 10 mm/mV and 25 mm/second shows
T wave alternans.

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ECG 6d. Precordial rhythm strip of the same patient at a calibration of 20 mm/mV and 25 mm/second shows
T wave alternans.

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ECG 6e. Precordial rhythm strip of the same patient at a calibration of 20 mm/mV and 50 mm/second shows
T wave alternans.

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Figure 6a. In the left coronary arteriogram of the same patient, anteroposterior caudal view showed
significant stenosis in the LAD . There were no si,gnificant stenosis in the
left main coronary artery and Circumflex (Cx) coronary artery.




Figure 6b. No significant stenosis was observed in the right coronary arteriogram of the same patient.





ECG 7. The ECG above is from a middle-aged woman with supraventricular tachycardia.
QRS alternans is especially evident in leads C1 and C3.

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ECG 8a. The rhythm tracing above is from a 58 years-old man with moderate aortic valve stenosis and normal coronary arteries.
Sinus rhythm with left bundle branch block is present. The above tracing was recorded
while the patient was breathing deeply.
Echocardiography showed normal left ventricular function. Pericardial effusion was not observed.
The QRS amplitudes in leads V3 to V6 change progresively. QRS amplitudes may vary during deep breathing.

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ECG 8b. The rhythm tracing above was recorded
while the patient was holding his breath.
QRS amplitudes do not change anymore.

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ECG 9a. The ECG above is from a 13 years-old girl with supraventricular tachycardia and QRS alternans.
Her ECHOcardiographic examination was normal.

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ECG 9b. The ECG above belongs to the same girl.
It was recorded after termination of the tachycardia with intravenous Metoprolol.
Beat to beat QRS amplitude change (alternans) is not seen any more.

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ECG 10. The above ECG is from an old-man with dilated cardiomyopathy and normal coronary arteries.
The rhythm is ventricular tachycardia.
QRS alternans is best seen in leads V2 and V3.

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