The Disappearing Palpitations

Philip J. Podrid, MD

Disclosures

August 30, 2018

Figure 2. Courtesy of Dr Podrid

Discussion

The diagnosis is normal sinus rhythm, dual AV nodal pathways, nonconducted (blocked) PAC, escape junctional complex.

There is a regular rhythm at a rate of 72 beats/min. There is a pause or long RR interval (↔), and just prior to this pause a nonconducted premature P wave is seen in the ST segment (↑). This is a blocked or nonconducted premature atrial complex. The QRS complex duration is narrow (0.08 sec) and there is a normal morphology, although only three leads are shown. There is a P wave before each QRS complex (+), and the P-wave morphology is the same throughout. However, the PR intervals are not the same. Prior to the pause, the PR intervals are constant at 0.36 sec, while after the pause the PR intervals are also constant but shorter (0.22 sec). This is consistent with dual AV nodal pathways (one faster, the other slower conducting). The PR interval of the eighth QRS complex immediately following the pause (*) is even shorter (0.16 sec) and different from the other two PR intervals. This suggests that the P wave is not conducted and that the QRS complex is an escape junctional complex, resulting from the long pause. The QT/QTc intervals are normal (360/395 msec).

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