Atrial Fusion Beats

Report:

Sinus arrhythmia 64 – 80/min

Junctional rhythm 58/min

Atrial fusion beats

Nonspecific ST/T changes

Comment:

Three P waves in the middle of the tracing are clearly intermediate in shape between sinus P waves and the junctional retrograde ones; because of the same rate at the time, their transition to “pure” P waves is gradual.

The first sinus cycle is rather short, projecting a rate of 80/min. This is either an atypical sinus arrhythmia or a sinus extrasystole terminating the cycle. Different repolarisation suggests that the second beat may be premature and provides the subsequent pause for the junctional focus to take over.

Below (Fig 91a) are two more examples, from different patients, of atrial fusion.

The junctional rhythm seen here used to be called high nodal rhythm once. The term is now abandoned since it is neither high nor nodal.

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