ECG of the Week - 14th March 2016 - Interpretation

The following ECG is from a 34 yr old female who presented to the Emergency Department complaining of progressive weakness. She has known Gitelman syndrome and recently had several medications changed.

Click to enlarge

Rate:

• 78 bpm

Rhythm:

• Regular
• Sinus rhythm

Axis:

• RAD (-33 deg)

Intervals:

• PR - Normal (~170ms)
• QRS - Normal (80ms)
• Apparent QT - 560ms (QTc Bazette 640 ms)
• Due to T-U fusion
• See labelled image below

Additional:

• Massive U waves
• Mimic T waves - see labelled image below
• Nearly merging into subsequent P waves
• T wave inversion leads V1-2

T & U Waves Labelled in leads V2-3
Click to enlarge

Interpretation:

• ECG features consistent with hypokalaemia

What happened ?

The patient had urgent electrolytes which showed:

• K              1.7                [3.4 - 5.5 mmol/L ]
• Cor Cal     2.45             [2.20 - 2.55 mmol/L]
• Mg            0.73             [0.70 - 1.20 mmol/L]

She was admitted to the HDU and a PICC line inserted due to high K replacement requirements.
The patient made an uneventful recovery and was discharges once her potassium reached a consistently safe level.
For a bit more information check out:

• LitFL - You Can Beat the Feeling - A Rare Cause of  (& Review of) Hypokalaemia
• NCBI - Gitelman Syndrome

References / Further Reading

Life in the Fast Lane

• Hypokalaemia ECG Library

Textbook

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