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This post is an interpretation of the ECG Case 205

• Rate: ~42 bpm
• Rhythm:
  • Regularly irregular
    • Complexes occurring in paired group
  • Flat baseline without atrial activity
• Axis:
  • 1st Complex in pair
    • Normal (70 deg)
  • 2nd Complex in pair
    • LAD(-45 deg)

• Intervals:
  • 1st Complex in pair
    • QRS – Normal (80ms)
    • QT – 520ms
  • 2nd Complex in pair
    • QRS – Normal in limb leads, Prolonged in V1-3 (80-120ms)
    • QT – 440ms
• Segments:
  • 1st Complex in pair
    • ST Depression in leads II, aVF
  • 2nd Complex in pair
    • Minimal ST elevation in lead aVR
• Additional:
  • 1st Complex in pair
    • T wave inversion in II, III, aVF
    • Biphasic T in lead V3
  • 2nd Complex in pair
    • RsR’ Morphology in V1-3
    • Inverted notching terminal portion QRS in II, III, aVF also positive notching in aVL
      • ? Retrograde P waves ? Secondary to conduction delay

Interpretation

Escape bigeminy in setting of sinus arrest / sinus exit block

Differential of causes:

• Ischaemia
• Electrolyte disturbance
• Acid-base disturbance
• Cardiotoxic drugs
• Sinus node dysfunction
• Hypothermia
• Multifactorial combination of above

What happened next ?

Bloods showed:

• Acute on chronic renal failure
• Metabolic acidosis – pH 7.0 Bicarb 7.0
• K 6.0

Therapy with isoprenaline, sodium bicarb, cessation of cardiotoxic medication, and dialysis.

Following acute episode found to have sinus pauses on telemetry necessitating pacemaker insertion.

READ MORE: ECG Interpretation: All you need to know