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This post is an answer to the ECG Case 241

• Rate: Mean ventricular rate 24 bpm
• Rhythm: 
  • Pair ventricular beats without fixed R-R intervals 
  • Absent P waves
  • Regularly undulating baseline best seen lead aVL
• Axis: Normal
• Intervals:
  • QRS – Prolonged (120ms)
  • QT – 580ms (measured in V2 but T wave end difficult to see in other leads)

• Additional / Segments:
  • Paucity of QRS complexes
    • Nil ventricular beats seen in leads aVR, aVL, aVF, V4-6
  • T wave inversion in leads II and III

Interpretation

• Severe bradycardia 
• Atrial fibrillation
• Associated hypotension and altered GCS

General differentials for this ECG would include:

• Sinus node dysfunction
• Ischaemia
• Hypothermia
• Drug toxicity – calcium channel blockers, beta blockers, digoxin
• Electrolyte abnormality

The patient had a normal core temperature, was on two potential culprit drugs metoprolol and digoxin and had an underlying dysrhythmia (chronic AF). 

What happened next ?

Thankfully the patient responded quickly to a bolus of atropine and iv crystalloid whilst an urgent VBG was obtained and external pacing pads were applied. The patient had a normal potassium, calcium, magnesium and essentially normal pH.

The patient was treated with 2 vials of digoxin Fab with consistent improvement in heart rate and blood pressure following Fab therapy. Further bloods revealed new renal impairment likely secondary to recent GI illness and nephrotoxic drugs.

The patient was admitted to the HDU for ongoing cardiac monitoring and iv fluid replacement. His renal function improved within 24 hours, digoxin was ceased and his medications were revised to remove unnecessary and potentially toxic drugs.

READ MORE: Pearls in Syncope ECG Interpretation