ECG Case 107

86 yr old male referred by his General Practitioner with worsening renal failure. He has a history of atrial fibrillation with bradycardia for which he had a PPM inserted. His medications include metoprolol.

ECG Case 107 LITFL Top 100 EKG

Describe and interpret this ECG

ECG ANSWER and INTERPRETATION

Rate:

  • Mean ventricular rate ~24 bpm

Rhythm:

  • Irregular ventricular rhythm
  • No visible P waves
  • Irregular pacing spikes mean rate of 43 bpm
  • No evidence of capture

Axis:

  • Normal

Intervals:

  • QRS – Prolonged

Additional:

  • ST depression with T wave inversion leads II, III, aVF

Interpretation:

  • Pacemaker failure to capture
  • Underlying marked slow atrial fibrillation

CLINICAL PEARLS

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

Further reading:


CLINICAL OUTCOME

What happened next?

The patient had moderate renal failure with a normal potassium.

CXR showed no lead abnormality and lead placement appeared unaltered.

His metoprolol was ceased and the pacemaker threshold was reprogrammed with resultant 100% capture.


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Emergency Medicine Specialist MBChB FRCEM FACEM. Medical Education, Cardiology and Web Based Resources | @jjlarkin78 | LinkedIn |

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