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Monday 6 July 2026

Peer Reviewed

ECG education

Is this a junctional tachycardia?

Vivienne Miller

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Abstract

An ECG showing a narrow-QRS suggests the presence of a junctional tachycardia.

Key Points

Junctional tachycardias present with a rapid heart rate (usually between 140 and 250 bpm) and are due to an abnormal re-entrant circuit near the AV node and the bundle of His. Typically, the abnormal impulses are conducted retrogradely to the atria and anterogradely to the ventricles.
Both AVJRT and accessory pathway-mediated tachycardias (such as Wolff–Parkinson–White syndrome) can typically be terminated using adenosine, and often respond to carotid massage or other forms of vagal stimulation.
Atrial tachycardias and flutters are not usually terminated by adenosine or vagal manoeuvres, and continue with AV block and dissociation (especially after use of adenosine).