What Do You Think 20

39-year old one single-handed, one-eyed, musketeer with congenital dislocation of the hips.

Holter monitor.

Report says: Atrial and multifocal ventricular ectopics 

What do you think?

The rhythm is sinus (red arrows) with atrial bigeminy (blue arrows).

The atrial ectopics are conducted with ventricular aberration.

To summarize:

•       Aberrant conduction results from intermittent uneven physiologic refractoriness in the ventricular conducting system from an early supraventricular beat.

•      There is QRS widening usually with a right bundle branch block configuration, consequent to a delay or block in that bundle or a more peripheral branch.

Let us review the action potentials in the bundle branches.

With frequent atrial ectopy, search for normal and aberrant conduction.

With a coupling interval of 640 ms, the atrial ectopic is conducted normally (red highlight). A slightly shorter coupling interval and there is aberrant ventricular conduction with a right bundle branch block (yellow highlight).

Although aberrancy is usually conducted with a right bundle branch block, a left bundle branch block can also occur even within the same tracing.

Atrial fibrillation with a rapid ventricular response. There is right bundle branch block aberration (RBBB, red highlight) after a “long-short” period and left bundle branch block aberration (LBBB, yellow highlight) also after a “long-short” period.

Our case:

Each of the atrial ectopics in the bigeminal run has a different conduction.

Normal (red highlight), right bundle branch block (yellow highlight) and left bundle branch block (blue highlight).

Easy!