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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