What Do You Think 8

32-year old professional elite footballer with previous palpitations and a syncopal episode after scoring a goal. 

Holter monitor the next day:

Recovering well since implantation of an ICD.

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What do you think?

This may be the most important ECG I have ever presented.

Let us relook at the Holter recording.

• The reported diagnosis is V-Run(ventricular tachycardia) (red highlight).
• The background rhythm is atrial fibrillation with a rapid ventricular response (yellow and green highlight).
• There is a run of a broad QRS tachycardia(blue highlight), marginally faster than the atrial fibrillation ventricular response, but still irregular (R-R intervals at the top of the tracing).
• There are a number of recognised Holter monitor lead configurations that are used. When the narrow QRS is negative as in the middle tracing, it is V1 and thus the tracing shows a right bundle branch block configuration.

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The diagnosis is NOT ventricular tachycardia, but rather atrial fibrillation with a rapid ventricular response, conducted intermittently with aberration.

I regularly see runs of ventricular aberration almost always reported as ventricular tachycardia.I often wonder how many ICDs are implanted due to an incorrect interpretation?

‍I had planned to finish here, but the topic is so important, I will repeat it for the 100^th time.

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What is aberration?

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

Aberration may occur for a single complex (atrial ectopic) or many.

Here are the classic features with an isolated atrial ectopic:

The rsR’/rSR’ in V1 or V2 are called rabbit’s ears.

With atrial ectopy, search for ectopics where the R to R prematurity is slightly longer than the ectopic with aberration (red highlight) resulting in normal conduction (yellow highlight).

Note that with aberration the QRS width and appearance is more normal in V6.

Aberration was first described in atrial fibrillation by Gouaux and Ashman in 1947 and frequently referred to as the Ashman phenomenon (easier to say or remember than Gouaux). Because the refractory periods are dependent on the cycle length of the preceding cycle, they often demonstrate a long cycle(red highlight), short cycle (yellow highlight) appearance. Again a narrower QRS in V6.

With irregular atrial tachyarrhythmias, because of the varying R-R intervals, there may be different levels of aberration (red highlight). Once again, the diagnosis of ventricular tachycardia is incorrect (yellow highlight).

Aberrant conduction may also occur with supraventricular tachycardia (red highlight).

Aberration can still be diagnosed even if V1 is not available.

The rhythm is atrial fibrillation with a rapid ventricular response. The middle lead has at all R wave (red highlight) and is therefore not V1. The aberrant complexes have deep S waves (yellow highlight).

Left bundle branch block aberration (red highlight) is much harder to diagnose except at electrophysiology studies. Here is an ECG example:

V1 is present and there are long-short sequences. Again ventricular tachycardia (yellow highlight).

To be absolutely sure, look for right bundle branch block aberration in the same tracings (yellow highlight).