ECG of the Week: ECG of the Week - 17th October 2016

Wednesday, 19 October 2016

ECG of the Week - 17th October 2016 - Interpretation

The following ECG is from a 76 yr old male who had an episode of syncope whilst gardening. This is an ECG that was faxed from a rural location for specialist advice and highlights the difficulties faced when interpreting an ECG of less than ideal quality.

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Rate:

90 bpm

Rhythm:

Regular
Sinus rhythm

Axis:

Intervals:

PR - Prolonged (~220ms)
QRS - Prolonged (140ms)
QT - 400ms

Additional:

RBBB Morphology

rSR' V1

Interpretation:

Bifascicular block (RBBB + LAFB) with PR Prolongation
Clinical setting of syncope

So it's a trifasicular block ?

Well yes and no.

Many people refer to the combination of bifasicular block with a 1st or 2nd degree AV block as a 'trifasicular block', this term is obviously incorrect as a block of all three fasicles should result in complete heart block.
Further to the inaccurate nature of the term the AHA 2009 Recommendations for the Standardization and Interpretation of the Electrocardiogram specifically recommended the term 'trifasicular block' not be used due to the variation in anatomy and pathology producing the pattern.
On this surface ECG it isn't possible to tell whether all three fasicles are affected as the pr prolongation may be due to disease at the AV node, the left posterior fasicle, or the His bundle.
The AHA 2008 guidelines for PPM insertion are clear that an incidental bifasicular block with pr prolongation in the asymptomatic patient does not warrant PPM insertion (LoE: B, Class III recommendation) but in the setting of syncope are an indication for PPM insertion.

What happened ?

The patient was transferred to a tertiary center and underwent an uneventful PPM insertion.

References / Further Reading

Life in the Fast Lane

Textbook