Wednesday, 17 December 2014

ECG of the Week - 15th December 2014 - Interpretation

This week's ECG is from a 76yr old male who presented to the Emergency Department following an episode of syncope at home. He has a past history of ischaemic cardiac disease, prior CABG and hypertension. He reported no chest pain pre- or post-event, nil recent symptoms and 'was back to normal' when reviewed in the ED. His medications were aspirin, low dose slow release calcium channel blocker and clopidogrel. All vital signs were within normal limits. 
Check out the comments from our original post here.
His ECG is below:




Click to enlarge


Rate:

  • 66 bpm
Rhythm:
  • Sinus Arrhythmia
Axis:
  • Normal
Intervals:
  • PR - Normal (~160ms)
  • QRS - Normal (100ms)
  • QT - 400ms
    • The end of the T wave should be used to measure the Q-T interval as the U waves can be identified separately. In cases of T-U fusion the QT interval is artificially prolonged, this is commonly seen in hypokalaemia.
Segments:
  • PR & ST depression leads I, II, aVF, V4-6
  • Minimal PR & ST elevation lead aVR

Additional:
  • U waves leads II, aVF, V1-5
  • T-U depression precordial leads
Interpretation:
  • ECG features suggestive of hypokalaemia / hypomagnesaemia
  • Non-diagnositc ECG

What happened ?

The patient had normal cardiac biomarkers and normal electrolytes including potassium, calcium and magnesium. During his Emergency Department stay he complained of episodic feelings of dizzy and diaphoresis, a copy of his rhythm strip during one episode is shown below.

Click to enlarge
The rhythm strip shows two episodes of significant ventricular pauses, duration 6.2 sec and 6.7 seconds. Some non-conducted atrial activity can be seen, the apparent pacing spikes on the strip are artifact. Given his telemetry findings he was taken for pacemaker insertion from the Emergency Department. This case highlights how non-specific the ECG features can be in patients with significant underlying dysrhythmia and the need to utilize telemetry monitoring. 

Some other questions to consider:

  • Which patient's do you place on telemetry in your Emergency Department / hospital?
  • Who looks at the telemetry monitor ?
  • Do you know how to retrieve information from your telemetry system ?


References / Further Reading

Life in the Fast Lane

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