Friday, 6 June 2014

ECG of the Week - 2nd June 2014 - Interpretation

This ECG is from a 65 yr old female who presented to the Emergency Department complaining of chest pain.
Check out the comments on our original post here.

Click to enlarge

  • 72 bpm
  • Regular
  • A-V Sequential pacing
    • Nil p wave visible
  • Nil native atrial or ventricular activity noted
  • Extreme / NW axis (-110 deg)
  • QRS - Prolonged (200ms)
  • QT - 560ms (QTc Bazette 380-400 ms)
  • Discordant ST segment change
    • Some commenters were concerned about potential ST elevation in aVR. I think the J-point in this lead is subtly depressed
    • I think the significant QRS prolongation and fragmentation is causing some confusion as to the J-point location
    • The image below shows leads aVR and aVL with the green lines denoting the end of the QRS complex and the blue line the baseline to help show the relative positions of the QRS complex, J-point, and ST segment.
Click to enlarge

  • Ventricular pacing consists of 2 spikes ~20-40 apart
    • Best seen in right precordial leads
    • Like LV pacing (small spike) followed by RV pacing (large spike)
    • Referred to as LV-RV Offset
  • Negative QRS vector leads I, II, III, aVF, V2-6
    • Due to infero-apical lead positioning
  • Wide tall R wave lead V1
    • Predominant LV capture
  • Notching within QRS complex
    • Likely reflects significant myocardial scarring and injury as does QRS prolongation

  • Cardiac Resynchronization Pacing
    • Bi-ventricular pacing

This patient had ischaemic dilated cardiomyopathy with old ECGs showing same pacing morphology as seen here.
I've included the patient's chest x-ray below as we don't encounter many bi-vent pacemakers and I thought it was worth sharing.

Click to enlarge

Click to enlarge

For more on Cardiac Resynchronization Therapy (CRT) check out the following resources:

References / Further Reading

Life in the Fast Lane

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

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