What are the symptoms of digoxin toxicity?

Symptoms of Digoxin Toxicity

Digoxin toxicity presents with characteristic cardiac arrhythmias, gastrointestinal symptoms, and neurological disturbances, with severity depending on serum concentration and individual factors. 1

Cardiac Manifestations

• Typical arrhythmias include enhanced atrial, junctional, or ventricular automaticity (with ectopic beats or tachycardia) often combined with atrioventricular block 1
• Ventricular tachycardia that is fascicular or bidirectional in origin is highly suggestive of digoxin toxicity 1
• Various rhythm disturbances may occur, including:
  • First-degree, second-degree (Wenckebach), or third-degree heart block (including asystole) 2
  • Atrial tachycardia with block 2
  • AV dissociation 2
  • Accelerated junctional (nodal) rhythm 2
  • Unifocal or multiform ventricular premature contractions (especially bigeminy or trigeminy) 2
  • Ventricular tachycardia and ventricular fibrillation 2
• Severe digoxin overdose can cause hyperkalemia and cardiac standstill 1

Gastrointestinal Manifestations

• Anorexia 1, 2
• Nausea 1, 2
• Vomiting 1, 2
• Diarrhea 2
• Abdominal pain (rare) 2

Neurological Manifestations

• Visual disturbances (blurred or yellow vision) 1, 2
• Changes in mentation/confusion 1, 2
• Headache 2
• Weakness 2
• Dizziness 2
• Apathy 2
• Mental disturbances (anxiety, depression, delirium, hallucination) 2

Diagnostic Considerations

• Diagnosis is established by the combination of:
  • Characteristic rhythm disturbances 1
  • Ancillary symptoms (visual disturbances, nausea, changes in mentation) 1
  • Elevated serum concentrations 1
• Overt digoxin toxicity is commonly associated with serum digoxin levels greater than 2 ng/mL, but toxicity may occur at lower levels 1, 2
• Toxicity can occur even when serum concentration is within therapeutic range (0.5-1.2 ng/mL) 1, 3

Risk Factors and Potentiating Conditions

• Hypothyroidism 1
• Hypokalemia 1
• Hypomagnesemia 1
• Renal dysfunction 1, 4
• Advanced age 1
• Low lean body mass 1
• Concomitant medications that increase digoxin levels:
  • Amiodarone 1, 4
  • Clarithromycin 1, 4
  • Erythromycin 1, 4
  • Itraconazole 1, 4
  • Cyclosporine 1, 4
  • Verapamil 1, 4
  • Quinidine 1, 4
  • Propafenone 1
  • Dronedarone 1

Differences in Children and Infants

• In children, cardiac arrhythmias are typically the earliest manifestation of toxicity, rather than gastrointestinal or CNS symptoms 2
• Most common arrhythmias in children include:
  • Sinus bradycardia (may be a sign of impending toxicity) 2
  • Conduction disturbances 2
  • Supraventricular tachyarrhythmias (atrial tachycardia with or without block) 2
  • Junctional (nodal) tachycardia 2
• Ventricular arrhythmias are less common in children 2

Management Considerations

• For mild cases: discontinue medication, monitor rhythm, and maintain normal serum potassium 1
• For severe intoxication (serum digoxin concentrations >4 ng/mL with serious arrhythmias): administer digoxin-specific Fab antibodies 1, 5
• Intravenous magnesium is often administered if ventricular arrhythmias are present 1
• Temporary pacing may be needed for atrioventricular block or asystole 1

Clinical Pearls

• Digoxin toxicity can occur during long-term therapy or after an overdose 3
• PR prolongation and ST segment depression alone should not be considered digoxin toxicity 2
• Early recognition of warning signs (bradycardia, gastrointestinal or neurological disorders) is essential 4
• Serum digoxin level monitoring is unreliable after administration of digoxin-specific Fab antibodies 1