Wednesday, 9 July 2014

ECG of the Week - 7th July 2014 - Interpretation

This week's ECG comes from the same patient as last weeks case (ECG of the Week - 30th June). You'll remember we had a 70yr old male who presented with chest pain, palpitations and hypotension. He underwent DC cardioversion and this is his post cardioversion ECG.
Check out the comments on our original post here.


Click to enlarge
Rate:
  • 78
Rhythm:
  • Regular
  • Sinus rhythm
Axis:
  • Normal
Intervals:
  • PR - Normal (~180ms)
  • QRS - Normal (100ms)
  • QT - 320ms (QTc Bazette 370 ms)
Segments:

  • ST Elevation leads V1 & V3 ?? aVF
  • ST Depression leads II, III, aVF, V5-6
  • ST segment analysis difficult due to baseline wander

Additional:

  • Deep symmetrical T wave inversion leads II, III, aVF, V5-6 
Interpretation:

Without more clinical information on the case including prior medical history, findings on serial ECG's, old ECG's, and result of further investigations post this episode e.g. echo or angio it's difficult to give a clear conclusion to this case and ECG.

The broad differentials for the findings on this ECG are:

  • Ischemia
  • Structural Heart Disease
  • Cardiac T-wave Memory

T-wave memory is an interesting phenomenon that could explain the marked T wave changes seen on this ECG. It results in transient T wave changes following a period of abnormal ventricular conduction e.g. ventricular tachycardia, paced rhythms, intermittent bundle branch block or aberrant conduction. There is a recent paper by Vakil that is freely available (linked to below) that contains a nice overview of T-wave memory, proposed mechanisms, and a case example.The deep T wave inversion on this ECG correspond to the leads in which a negative QRS was seen in the patients pre-cardioversion ECG (case here) a finding consistent with T-wave memory. Patient's often require work-up to exclude underlying ischaemia or structural disease but cardiac T-wave memory is a benign and self-resolving condition in itself.

References / Further Reading

Article

  • Vakil K, Gandhi S, Abidi KS, et al. Deep T-Wave Inversions: Cardiac Ischemia or Memory? JCvD 2014;2(2):116-118. Full text here.

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