This document discusses various electrolyte abnormalities and their ECG manifestations. Hyperkalemia causes widened and low amplitude P-waves, widened QRS complex with potential fusion of the QRS-T segment and loss of the ST segment, and tall tented T-waves. Hypokalemia results in ST depression and flattened T-waves and possible negative T-waves. Hypercalcemia speeds repolarization, causing tall peaked T-waves at mild levels and extremely wide QRS complex with low R-waves and disappearance of P-waves at severe levels. Hypocalcemia causes a narrowed QRS complex, reduced PR interval, flattened and inverted T-waves, and prolonged QT and ST intervals. Hypomag

1. Electrolyte and metabolic
ECG abnormalities
Mr. Aby Thankachan,M.Sc(N), Ph.D (N)
Asst Professor
HICON, CBE

2. HYPERKALEMIA
Normal range - 3.6 to 5.2 millimoles per liter
(mmol/L)
ECG characteristics of hyperkalemia, high blood
potassium:
• P-waves are widened and of low amplitude due to
slowing of conduction
• QRS complex:
– QRS widening
– fusion of QRS-T

3. – loss of the ST segment
• Tall tented T waves
The initial part of the QRS complex is often spared as
purkinje fibers are less sensitive to hyperkalemia.
These changes can also occur in acidosis (via the
same mechanism) and during Class IC anti-
arrhythmic intoxication.
• At concentrations > 7.5 mmol/L atrial and ventricular
fibrillation can occur.

6. ECG 1

7. ECG 2

8. After Potassium Correction

9. Potassium of 9.4 mmol/L

10. Hypokalemia
Hypokalemia, low blood potassium, results in:
• ST depression and flattening of the T wave
• Negative T waves
• A U-wave may be visible

14. Potassium level of 1.5

16. Hypercalcemia
Normal Range 8.5 to 10.5 milligrams per
deciliter (mg/dL)
Hypercalcemia, high blood calcium, speeds
repolarization.
Characteristics of hypercalcemia:
• Mild: broad based tall peaking T waves
• Severe: extremely wide QRS, low R wave,
disappearance of p waves, tall peaking T
waves.

18. Calcium – 4.6 mmol/L

19. Hypocalcemia
ECG-characteristics of hypocalcemia, low
blood calcium:
• Narrowing of the QRS complex
• Reduced PR interval
• T wave flattening and inversion
• Prolongation of the QT-interval
• Prominent U-wave
• Prolonged ST and ST-depression

21. Hypocalcaemia prolongs the ST segment
causing QT prolongation

22. Hypermagnesaemia
• The normal range for blood magnesium
level is 1.7 to 2.2 mg/dL (0.85 to 1.10
mmol/L).

24. Hypomagnesaemia
• ECG changes in isolated hypomagnesaemia
– Prolonged PR interval
– Prolonged QT interval

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