ECG of the Week – 25th April 2016 – Interpretation

The following ECG is from an 89 yr old male who presented to the Emergency Department complaining of dizziness.


Click to enlarge

Rate:
  • 54 bpm
Rhythm:
  • Sinus arrhythmia
Axis:
  • LAD (-73 deg)
Intervals:
  • PR - Prolonged(~280ms)
  • QRS - Prolonged (~150ms)
  • QT - 480-500ms (QTc Bazette 450-470 ms)
Segments:
  • Discordant ST depression leads I, aVL, V1-2
  • Concordant ST depression lead V4
Additional:
  • RBBB Morphology
  • Broad P wave with notching 
  • T wave inversion leads I, aVL, V1-4
Interpretation:
  • PR Prolongation
  • Bifasicular block
    • RBBB with LAFB
So it's a trifasicular block ?

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. 
Those patients with bifasciular block, pr prolongation and a history of syncope or likely arrhythmia, should be referred to cardiology team for telemetry, review of current medications, and consideration for PPM insertion.
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).


References / Further Reading

Life in the Fast Lane

Textbook
  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.

ECG of the Week – 18th April 2016 – Interpretation

The following ECG is from an 84 yr old male who presented with chest pain and dizziness. He had a dual chamber pacemaker in-situ inserted for symptomatic bradycardia.

 

Click to enlarge

Rate:
  • Mean ventricular rate 78 bpm
Rhythm:
  • Nil p waves visible
  • Bigemny
    • V-paced complex followed by premature ventricular complex
V-Paced Complexes (#2,4,6,8,10,12)


Axis:
  • LAD
Intervals:
  • QRS - Prolonged (150ms)
Segments:
  • Appropriate discordant ST segment change
    • Note ST depression in V2 as mentioned in comments but this is discordant to positive QRS (not typical LBBB morphology) and as such should be considered Sgarbossa negative
Premature Ventricular Complexes (#1,3,5,7,9,11,13)


Axis:
  • Normal
Intervals:
  • QRS - Prolonged (130ms)
Segments:
  • Discordant ST / T wave changes

Interpretation:
  • V-paced rhythm with bigemny
  • Underlying sinus node dysfunction - nil native p waves
What happened ?

Despite a mean ventricular rate the patient's pulse rate was only ~40 bpm, i.e. the PVC's were not resulting in 'mechanical' capture. 
The patient had minor electrolyte abnormalities corrected and rate modulating drugs were reduced with resultant decrease in PVC frequency and increased mechanical pulse rate.
Pacemaker interrogation revealed no setting issues and serial troponins were negative.
The patient was discharged with ongoing cardiology follow-up.

References / Further Reading
Life in the Fast Lane

Textbook
  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.