- Normal serum magnesium = 0.8 – 1.0 mmol/L.
- Hypomagnesaemia = <0.8 mmol/L
ECG changes in Hypomagnesaemia
- The primary ECG abnormality seen with hypomagnesaemia is a prolonged QTc.
- Atrial and ventricular ectopy, atrial tachyarrhythmias and torsades de pointes are seen in the context of hypomagnesaemia, although whether this is a specific effect of low serum magnesium or due to concurrent hypokalaemia is uncertain.
- Nevertheless, correction of serum magnesium to >1.0 mmol/L (with concurrent correction of serum potassium to >4.0 mmol/L) is often effective in suppressing ectopy and supraventricular tachyarrhythmias, while a rapid IV bolus of magnesium 2g is a standard emergency treatment for torsades de pointes.
- Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography
- Hampton, JR. The ECG In Practice, 6e
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric, 6e
- Wagner, GS. Marriott’s Practical Electrocardiography 12e
- Chan, TC. ECG in Emergency Medicine and Acute Care
- Wang, K. Atlas of Electrocardiography
- Mattu, A. ECG’s for the Emergency Physician
LITFL Further Reading
- ECG BASICS — Waves, Intervals, Segments and Clinical Interpretation
- ECG A to Z by diagnosis –alphabetical diagnostic approach to the ECG
- ECG CLINICAL CASES — ECG’s placed in clinical context with a challenging Q&A approach
- 100 ECG Quiz — Self-assessment tool for examination practice
- ECG Reference SITES and BOOKS — the best of the rest
- LITFL ECG IMAGE Database — Searchable database of LITFL ECG’s
- ECG and Cardiology Eponymous Syndromes — Cheats guide to eponymous emancipation
- ECG Exam Template — a framework for answering ECG exam questions.