Electrolyte Disorders

Author(s)	J.S.S.G. de Jong
Moderator	T.T. Keller
Supervisor
some notes about authorship

Hypercalcemia

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.

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

Hyperkalemia

ECG characteristics of hyperkalemia, high blood potassium:

• Tall peaked T waves
• Flattening p-waves. In extreme hyperkalemia p-waves may disappear altogether.
• Prolonged depolarization leading to QRS widening (nonspecific intraventricular conduction defect) sometimes > 0.20 seconds

At concentrations > 7.5 mmol/L atrial and ventricular fibrillation can occur.

• 
  Consecutive ECGs of a patient with hyperkalemia. ECG1
• 
  Consecutive ECGs of a patient with hyperkalemia. ECG2
• 
  Consecutive ECGs of a patient with hyperkalemia. After correction of potassium levels. ECG3
• 
  Another patient, potassium of 9.4 mmol/L

Hypokalemia

Hypokalemia, low blood potassium, results in:

• ST depression and flattening of the T wave
• Negative T waves
• A U-wave may be visible

• 
  patient A
• 
  patient A
• 
  patient B
• 
  Patient C, Potassiumlevel of 1.5