Wednesday, 24 April 2013

ECG of the Week - 22nd April 2013 - Interpretation


This ECG is from a 78 yr old male who presented with a 2 day history of lethargy and dizziness

He has a history of ischaemic heart disease, type 2 DM, hypertension, and chronic renal failure. 
Medications include calcium-channel blocker, beta-blocker, and ACE-inhibitor.

Conscious with systolic BP of 70 !





Click to enlarge


Rate:
  • ~42
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 V1-3 (80-120ms)
    • QT - 440ms
Segments:

  • 1st Complex in pair
    • ST Depression leads II, aVF
  • 2nd Complex in pair
    • Minimal ST elevation lead aVR

Additional:

  • 1st Complex in pair
    • T wave inversion II, III, aVF
    • Biphasic T lead V3
  • 2nd Complex in pair
    • RsR' Morphology V1-3
    • Inverted notching terminal portion QRS II, III, aVF also positive notching aVL
      • ? Retrograde P waves ? Secondary to conduction delay

Interpretation:

  • Escape bigeminy
    • In setting of sinus arrest / sinus exit block
  • Non-specific ST / T wave changes
Differential of causes:
  • Ischaemia
  • Electrolyte disturbance
  • Acid-base disturbance
  • Cardiotoxic drugs
  • Sinus node dysfunction
  • Hypothermia
    • Multifactorial combination of above


What happened ?

Bloods showed:
  • Acute on chronic renal failure
  • Metabolic acidosis - pH 7.0 Bicarb 7.0
  • K 6.0
Tx with isoprenaline, sodium bicarb, cessation of cardiotoxic medication, and dialysis.

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

References / Further Reading

Life in the Fast Lane

  • Sinus Arrest here
  • Sinoatrial exit block here
Textbook
  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.