Saturday, 2 July 2016

ECG of the Week - 27th June 2016 - Interpretation

The following ECG is from an elderly female who presented with malaise, weight loss and chest pain.


Click to enlarge

Rate:
  • 72 bpm
Rhythm:
  • Regular
Axis:
  • Right axis deviation
Intervals:
  • QRS - Prolonged (120ms)
  • QT - Measured in lead aVL 440ms
  • QT - Measured in leads V4-5 620-640ms
Segments:
  • ST Elevation leads aVR, aVL, V1-3
  • ST Depression leads II, III, aVF, V4-6
Additional:
  • U waves best seen in precordial leads
  • Associated apparent QT prolongation in precordial leads vs limb leads due to T-U fusion
  • T wave inversion leads II, III, aVF, V4-6
  • LVH criteria
    • V4 R >26mm
    • Largest Precordial S + R wave >45mm
    • R wave in aVF ~20mm
Interpretation:

  • Features of hypokalaemia
    • Prominent U waves
    • Apparent QT prolongation due to T-U fusion in precordial leads
    • Cause of / or contributing to T wave inversion & ST depression
  • T wave & ST segment changes could be due to LVH
  • Potential for ACS
    • Needs serial ECG's

What happened ?

Patient's potassium was 2.1 mmol/L. Serial troponins were negative. Partial resolution of ST segment depression and resolution of U waves once K was corrected. 

Hypokalemia ECG's on the Web

  • ECG of the Week - We've had some examples of hypokalemia previous check them out here here.
  • Dr Smith's ECG Blog - multiple great examples of hypokalaemic ECGs here.
  • Dr Ken Grauer's ECG Interpretation - A great walk through of ECG changes in hypokalaemia here.
  • Amal Mattu's ECG Video - ECG findings in severe hypokalaemia here.
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.