Wednesday, 22 March 2017

ECG of the Week - 20th March 2017 - Interpretation

The following ECG is from a 24yr old female who presented with dysponea. Background history of SLE with known cardiac and renal involvement.

Click to enlarge
Key features:
  • Bradycardia rate ~42bpm
  • Irregular rhythm
  • Atrial activity visible but unrelated to QRS complexes
  • 2 distinct QRS morphologies
    • Complexes #1,2,4,5,7
    • Complexes #3,6
  • Marked QRS Prolongation
  • Massive T waves in leads I, aVF, V4-6
  • Deep T wave inversion leads V1-3

Looking at the ECG in isolation the major life-threatening concern for these features would be hyperkalaemia. This would be consistent with the patient's history of renal disease secondary to SLE. Contributing factors could also be severe acid/base disturbance, again consistent with renal failure. Given known cardiac SLE involvement it is possible the patients baseline ECG may have QRS prolongation and longstanding ST / T wave changes.
An urgent blood gas was performed which showed a potassium of 9.2 mmol/L and pH 7.1 !
The patient was also acutely fluid overloaded as the cause of her dysponea.

What happened ?
Following initial treatment of salbutamol nebuliser, iv calcium gluconate, iv dextrose / insulin and sodium bicarb' there was significant improvement in the ECG.
Click to enlarge
 The ECG now shows restoration of sinus rhythm with narrowing of QRS and classically peaked T waves.The patient's potassium was now 8.6 mmol/L with no change in pH !She was taken for urgent dialysis.
References / Further Reading
Life in the Fast Lane
  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.

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