Wednesday, 15 January 2014

ECG of the Week - 13th January 2014 - Interpretation

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).
Check out the comments on the original post here.




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.