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This post is an answer to the ECG Case 329

• Rate: Mean rate 66 bpm
• Rhythm:
  • Irregular
  • Complexes #1-3, 5-6, 8-10
    • Sinus rhythm
  • Complex #4
    • PVC
  • Complexes #7 & 9
    • No convincing preceding P wave
    • Similar morphology as sinus complexes
    • Potential junctional escape during period of sinus arrest / pause

• Axis: Normal
• Intervals:
  • PR – Normal
    • During sinus conduction
  • QRS – Prolonged (120ms)
  • QT – 520ms (QTc Bazette 565 ms)
    • Calculated in lead II using consecutive sinus complexes
• Additional:
  • Absence of typical BBB pattern
  • ST Depression in leads II, III, aVF, V3-6
  • Biphasic (down-up) T wave in inferior leads
  • Baseline artifact
  • Notching in ST segment in complexes #6,8,10
  • Precedes period of sinus pause and junctional escape
  • ? Increased sinus automaticity during ventricular refractory period

Interpretation

• QT Prolongation
• ST Depression
• Increased automaticity
  • PVC, Rhythm disturbance, PJC, possible increased sinus acitivty

Favors hypokalemia and/or hypomagnesemia as the likely cause.

What happened next ?

The patient’s biochemistry results were:

• Na 131 mmol/L
• K 2.2 mmol/L
• Cl 73 mmol/L
• Bicarb 44 mmol/L
• Urea 20.3 mmol/L
• Creat 153 umol/L

Both calcium and magnesium were within normal limits. The patient was on a combination angiotensin II receptor antagonist and thiazide diuretic which was ceased and following electrolyte correction her confusion resolved.

READ MORE: Hypokalemia ECG Changes [With Examples]

SIMILAR CASES:

• ECG Case 189: Hypokalemia
• Hypokalemia in a Man With Generalized Weakness
• Hypokalemia as a result of Anorexia Nervosa and Diarrhea