Wednesday, 3 July 2013

ECG of the Week - 1st July 2013 - Interpretation

I don't have any clinical information on this ECG unfortunately.





Click to enlarge

Rate:
  • 60
Rhythm:
  • Regular
  • Atrial pacing throughout
Axis:
  • Normal (20 deg)
Intervals:
  • Pacing cycle length 960 ms
  • PR - Normal (~160ms)
  • QRS - Normal (100ms)
  • QT - 440ms (QTc Bazette ~ 450 ms)
Segments:

  • ST Elevation lead V1 (1mm)
  • Up-sloping ST segment aVR
  • ST Depression leads I, II, III, aVF, V4-6

Additional:

  • Early R wave transition
  • Prominent R wave V2
    • Height difficult to see
    • Suggestion R wave V2 > V3 possibility of lead misplacement but unlikely given local lead configuration
  • Voltage criteria Left Ventricular Hypertrophy
    • R wave lead I + S wave lead III > 25mm
    • R wave V5 31mm
    • R wave V5 + S wave V1 ~54mm

Interpretation:

  • Atrial pacing with capture
    • No clinical information on case so reason for PPM unknown
    • Large amplitude of pacing spikes suggests unipolar pacing
  • ECG features of LVH
  • Diffuse ST segment & T wave changes

The differential based on this ECG alone is broad and many of our commenter's recognised the need for clinical correlation and comparison with old ECG's to be fully able to interpret this ECG.

Some potential causes include:
  • LVH with 'strain pattern'
  • Post pacing cardiac memory
    • Likely dual chamber PPM
    • Read more in our recommended article below
  • Ischaemia
  • Cardiomyopathy 
  • Pulmonary Embolism

Cardiac Memory ?

Dr Razak has highlighted an article on post pacing T wave changes which includes a nice explaination of cardiac memory by Shvilkin et al which is freely available here.


References / Further Reading

Life in the Fast Lane

  • 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.