ECG of the Week - 24th July 2017 - Interpretation

The following ECG is from a 52 yr old female who was referred by her General Practitioner with confusion and abnormal biochemistry results.

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Rate:

• Mean rate 66 bpm

Rhythm:

• Irregular
• Complexes #1-3, 5-6, 8-10
• Sinus rhythm
• Complex #4
• PVC
• Complexes #7 & 9
• Nil convincing preceding P wave
• Similar morphology as sinus complexes
• Potential junctional escape during period of sinus arrest / pause

Axis:

• Normal

Intervals:

• PR - Normal
• During sinus conduction
• QRS - Prolonged (120ms)
• QT - 520ms (QTc Bazette 565 ms)
• Calculated in lead II using consecutive sinus complexes

Additional:

• Absence of typical BBB pattern
• ST Depression leads II, III, aVF, V3-6
• Biphasic (down-up) T wave in inferior leads
• Baseline artifact
• Notching in ST segment in complexes #6,8,10
• Precedes period of sinus pause and junctional escape
• ? Increased sinus automaticity during ventricular refractory period

Interpretation:

• QT Prolongation
• ST Depression
• Increased automaticity
• PVC, Rhythm disturbance, PJC, possible increased sinus acitivty

Favors hypokalaemia +/- hypomagnesaemia as the likely cause.

What happened ?

The patient's biochemistry results were:

• Na 131 mmol/L
• K 2.2 mmol/L
• Cl 73 mmol/L
• Bicarb 44 mmol/L
• Urea 20.3 mmol/L
• Creat 153 umol/L

Both calcium and magnesium were within normal limits. The patient was on a combination angiotensin II receptor antagonist and thiazide diuretic which was ceased and following electrolyte correction her confusion resolved.

References / Further Reading

Life in the Fast Lane

• Hypokalaemia

Textbook

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