Characteristics:

• Positive inotropic substance

Mechanism of action:

• Blockade of sodium–potassium–ATPase, causing an increase in intracellular calcium
  
• Among other features, slowing of conduction at the AV node

ECG characteristics:

• Trough-shaped ST segment depression

ECG characteristics:

ECG characteristics:

Etiology:

• Chronic laxative abuse, vomiting, diarrhea
  
• Diuretic treatment, hyperaldosteronism (Conn syndrome, liver cirrhosis, hepatic coma), renal potassium loss
  
• Diabetic coma
  
• Idiopathic hypokalemia

Mechanism of action:

• Hyperpolarization of the cell membrane via increase of the intracellular/ extracellular gradient
  
• Acceleration of phase 0
  
• Prolongation of phase 3
  
• Increase in the speed of electrical conduction

ECG characteristics:

• No changes in the QRS complex
  
• Depression of the ST segment
  
• Prolongation of the QT interval
  
• TU amalgamation