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This post is an answer to the Case – ECG Case 218

• Rate: Mean ventricular rate ~66 bpm
• Rhythm:
  • Sinus rhythm
    • Complexes # 1, 5, 6, 7, 9, 11
    • P waves difficult to see but best appreciated in leads V1 & V2
  • Ventricular Ectopics
    • Complexes # 2, 3, 8, 10
  • Premature Junctional Complex
    • Complex #4

• Axis: Normal
• Intervals for Sinus Complexes:
  • PR – Normal (~130ms)
  • QRS – Prolonged (140ms)
  • QT – 490ms (QTc Bazette ~ 500 ms) – Prolonged
• Segments:
  • Discordant ST / T wave changes with ventricular ectopic complexes
• Additional:
  • T wave inversion sinus complexes in leads I, II, II, aVL, V6
  • Ventricular ectopics occur close to T wave especially in complexes # 2 & 10

Interpretation

• Life-threatening electrolyte abnormalities
• ECG manifestations consistent with hypomagnesaemia and hypocalcaemia
  • QT Prolongation
  • QRS Prolongation
  • Multiple ectopic complexes
• Risk of Torsades de Pointes

What happened next ?

Biochemistry Results on admission:

• Creatinine 421 umol/L [70-150]
  • Patient’s baseline creatinine ~300 umol/L
• Mg 0.17 mmol/L [0.65-1.10]
  • Note K was normal
• Cor Cal 1.35 mmol/L [2.15-2.55]
• Ionised Ca 0.66 mmol/L [1.12 – 1.30]
• Phos 2.0 mmol/L [0.7-1.5]
• Alb 31 g/L [34-45]

The patient was admitted to the Critical Care Unit for cardiac monitoring and electrolyte replacement. Further biochemistry revealed an elevated Parathyroid Hormone 20.9 pmol/L [1.5 – 8.0], and mild vitamin D deficiency, consistent with secondary hyperparathyroidism due to chronic renal disease. With rehydration and electrolyte replacement the patient’s clinical condition improved and he was discharged.

Biochemistry on discharge showed:

• Creatinine 270 umol/L [70-150]
• Mg 0.76 mmol/L [0.65-1.10]
• Cor Cal 2.08 mmol/L [2.15-2.55]

SIMILAR CASE: Hyperkalemia and Hypocalcemia on ECG