Saturday, 20 June 2015

ECG of the Week - 15th June 2015 - Interpretation

This week's ECG is from an 82 yr old male who presented with worsening heart failure.

Click to enlarge
  • 60 bpm
  • Regularly irregular
  • Alternating Atrial (A) and Ventricular (V) pacing
  • LAD for both A-paced & V-paced complexes
  • QRS - Prolonged (160-180ms)

  • Discordant ST segment and T wave changes
  • Native ventricular complexes are Sgarbossa negative


  • A-pacing associated with native LBBB ventricular morphology
  • V-pacing associated with RBBB morphology
    • Frontal QRS axis ~-75 degrees with transition at V6


  • Alternating A & V pacing
  • Native LBBB
  • V-paced rhythm associated with RBBB morphology

Is RBBB morphology during right ventricular pacing always due to lead malposition ?

The short answer to this is no. There are cases in which an RBBB morphology can occur with appropriate right ventricular apical pacing.

In this case the patient had a chest x-ray which showed appropriate lead placement, for an example of RBBB morphology associated with lead malposition check out this case here.

Features which may assist in differentiating between lead malposition and correct placement are:
  • Frontal plane axis
  • Precordial transition point
  • Repositioning of leads V1-2

I would recommend the following freely available papers which both include a review of RBBB morphology during right ventricular pacing.
  • Erdogan O, Aksu F. Right bundle branch block pattern during right ventricular permanent pacing: Is it safe or not? Indian Pacing Electrophysiol J. 2007 Aug 1;7(3):187-91. PMID: 17684578   Full text here
  • Almehairi M, Baranchuk. Right Bundle Branch Block Morphology During Apical Right Ventricular Pacing. The Journal of Innovations in Cardiac Rhythm Management, 4 (2013), 1303–1304. Full text here

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.

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