|Click to enlarge|
- 90 bpm
- Sinus rhythm
- PR - Prolonged (~220ms)
- QRS - Prolonged (140ms)
- QT - 400ms
- RBBB Morphology
- rSR' V1
- 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
- Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.