Strip 27

sinus rhythm with conduction aberrancy


First Glance:

From across the room it looks like sinus rhythm with a regular wide complex.

Discussion:

The upper lead is ‘V’, a chest lead, and shows a subtle positive P wave with a normal PR interval (at 50% voltage calibration) and a wide complex QTS with a subtle rSr’ pattern. The lower lead is II and shows a positive bifid P at 50% voltage calibration, with a wide rSr’ as well. This bifid P might spark some suggestion of left atrial enlargement, but its relatively small size, short interval, and the fact that its peaks are 40ms or slightly less apart mean this is not a strong finding- especially on a tele strip.

With the predominantly negative forces in lead II we wonder whether there is some axis deviation here. With the rSr’ in V we wonder whether there is a RBBB (if the chest lead is in the classic septal distribution) or whether it is just nonspecific intraventricular conduction delay.

Wide complexes are generally signs of cardiac pathology, and new widening of the QRS suggests either pharmacologic widening or dysfunction of the conduction pathways secondary to ischemia, injury, or electrolyte abnormalities.

Wide complex QRS’s still pump blood however, and their major management issue is concern for progressive conduction disease that could result in a high-grade block, and that they provide evidence of cardiac disease.

Final Impression?

Sinus rhythm @ 85 bpm with wide complexes with unspecified conduction delay.

Management implications:

Check leads, evaluate with 12L.

 The Take-home Point:

A RBBB classically shows an rSR’ pattern in the septal leads, or possibly a broad R or qR. A LBBB classically shows a broad S wave in the lateral and/or high lateral leads. Neither require axis deviation to make the diagnosis, although LAD is common with LBBB. RBBB is not associated with any specific axis changes, and either right or left axis changes in the setting of RBBB should be investigated for the presence of an additional left bundle branch fascicular block.

 

 

1purple_starOne star strip. Students should identify the rhythm correctly.

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