ECG of the Week – 10th September 2018 – Interpretation

The following ECG is from a 95 year old male who presented following an episode of syncope.




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Rate:

  • Atrial rate 79 bpm
  • Pacemaker rate 79 bpm
  • Ventricular rate 12 bpm

Rhythm:

  • Regular atrial activity
  • Pacing spike following every PPM
  • Only 2 episodes of ventricular capture

Axis:

  • Likely LAD

Intervals:

  • QRS – Prolonged

Additional:

  • Abnormal QRS morphology in leads V1-3 not typical LBBB

Interpretation:

  • Loss of ventricular capture

Causes of pacemaker failures

In broad terms there is either a problem with the pacemaker signal generator, the connection to the patient or the patient. These can be further expanded:

  • Signal generator problems
    • End-of-life
    • Battery failure
    • Programming issue
    • Over or under sensing
  • Connection between unit and patient
    • Lead fracture
    • Lead malposition
    • Lead migration
    • Lead fibrosis
  • Patient factors
    • Progression of underlying disease
    • Ischaemia
    • Electrolyte / acid-base disturbance
    • Drug toxicity

What happened ?

The patient was stabilised with a combination of transcutaneous pacing and isoprenaline infusion. Pacemaker interrogation revealed increased impedance in the RV lead and increasing the voltage resulted in ventricular capture, this was likely due to early lead failure and the patient was transferred for PPM replacement.

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.

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