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

• You Can Beat the Feeling - A Rare Cause of (& Review of) Hypokalaemia
• Hypokalaemia ECG Library
• LVH

Textbook

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