ECG of the Week – 13th January 2014 – Interpretation

By | 15 januari 2014

This week’s ECG is from a 72yr old with known atrial fibrillation and a PPM in situ. He presents with several days of atypical chest pain. Medications include metoprolol, frusemide, and low molecular weight heparin (intolerant of warfarin).




Click to enlarge

Rate:

  • Mean ventricular rate ~78 bpm

Rhythm:

  • Irregularly irregular native ventricular activity
  • Nil clear p waves
    • Irregularity to baseline in leads II, III, V1-2
  • Single ventricular paced complex
    • Complex #6

Axis:

  • Normal

Intervals Native Complexes:

  • QRS – Normal (~70ms)
  • QT – 380ms
Intervals Paced Complex:
  • QRS – Prolonged (120ms)
  • QT – 420ms

Segments:

  • ST Elevation aVR
  • ST Depression leads I, II, V4-6
  • Discordant ST segment change in paced complex

Additional:

  • Paced complex occurs 1000ms following R wave peak of preceding complex
  • T wave inversion leads II, III, aVF, aVL, V4-5
  • Undulating baseline in inferior and precordial leads 
    • ? flutter vs U waves vs artifact

Interpretation:

  • Rate controlled atrial fibrillation
  • Single paced complex
  • ST / T wave changes non-diagnostic, consider
    • Ischaemia
    • Drug effects esp. digoxin
    • Electrolyte abnormality
    • Doesn’t quite meet voltage criteria for LVH


What happened ?

Serial ECG’s showed no dynamic changes, and serial troponins were negative.
Medication review confirmed the patient was not on digoxin.
He was discharged from the Emergency Department with planned out-patient cardiology follow-up with his usual specialist.

Sorry for the anti-climactic ending but the truth is that this is what happens to a significant portion of the patients we see with chest pain, non-dynamic longstanding ECG abnormalities, and negative cardiac biomarkers.

References / Further Reading

Life in the Fast Lane

  • Digoxin and the ECG here
  • Left ventricular hypertrophy here

Textbook

  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.

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