Is a premature beat originating from the AV node before the expected sinus impulse reaches it.

  On the contrary, the nodal beat in junctional escape comes late regarding to the expected sinus impulse.

  Since the impulse originates from the AV node, they usually lack a P wave preceding them.

  Less frequently, a P wave may preceede the narrow QRS complex with a P wave duration and a PR interval

      shorter than those of the sinus P wave.






ECG 1. Above is the ECG of a middle-aged man with normal coronary arteries.
Junctional premature beat is seen.
QRS complex has no preceding P wave.

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ECG 2. Above is the ECG of a 59 years-old man with coronary artery disease and heart failure.
Junctional premature beat is seen.
The P wave preceding the junctional beat is followed by a short PR interval.
This PR interval shortening is not due to accesory pathway, there is no delta wave.
This short PR interval is just due to coincidental timing of the junctional premature beat.
This is not an atrial premature beat since PP intervals and P wave configurations are the same.

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