Atrial Pacemaker: Failure to Sense

Report:

Sinus rhythm 89/min 1

PR interval 0.20 sec 1

Atrial demand pacemaker 3

Intermittent failure to sense 4

Right bundle branch block 1

Comment:

There are three atrial pacemaker beats. All three have a very early spike, always in the same spot. They fail to sense the preceding P wave and its QRS and are presumably escaping from the one before: hence the fixed coupling.

The unusual feature here is that there no other spikes in the trace – only three but all three successful.

In the tracing shown below, there is more widespread failure to sense – but not to pace; the only spike finding the atria responsive produces a “SVEB” identical to the three in the original tracing.

This patient does not appear to need pacing any more.

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