ECG of the Week - 5th June 2017 - Interpretation

The following ECG is from a 66 yr old female who presented to the Emergency Department complaining of dizziness and pre-syncope. She is awaiting an out-patient colonoscopy and had just completed her bowel prep.

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Rate:

• 66 bpm

Rhythm:

• Regular

Axis:

• Normal

Intervals:

• PR - Normal (~200ms)
• QRS - Normal (80ms)
• QT - 400ms (QTc Bazette 420 ms)

Additional:

• Partial RBBB Morphology
• Prominent U waves leads I, II, aVF, V4-6
• T-U fusion in lead III & V2
• Causing pseudo QT prolongation if these leads are used to measure QT

Interpretation:

• Features favor hypokalaemia
• U waves
• T-U fusion
• Clinical scenario of likely large fluid shifts secondary to bowel prep

What happened ?

The patients had a combination of hyponatraemia and hypokalaemia (2.4 mmol/L) and following electrolyte / volume correction her symptoms resolved. Repeat ECG showed resolution of U waves.

References / Further Reading

Life in the Fast Lane

• Hypokalaemia - ECG features
• Hypokalaemia - Case Overview
• Hyponatraemia - Cause and Diagnostic Approach

Textbook

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