What are the symptoms of digitalis toxicity?

Symptoms of Digitalis Toxicity

Digitalis toxicity presents with characteristic cardiac and non-cardiac manifestations that require prompt recognition and management to prevent life-threatening complications.

Cardiac Manifestations

• Arrhythmias - The most common and dangerous symptoms:
  • Enhanced atrial, junctional, or ventricular automaticity 1
  • Ectopic beats (atrial, junctional, ventricular) 1
  • Ventricular tachycardia 1
  • Bidirectional ventricular tachycardia (highly specific for digitalis toxicity) 2
  • Atrioventricular (AV) block (including advanced AV block) 1
  • Atrial fibrillation with slow ventricular response 1
  • Atrial tachycardia with block 2
  • Junctional tachycardia 2
  • Accelerated junctional rhythm 2
  • Multiple simultaneous arrhythmias (highly suggestive of digitalis toxicity) 2
  • Asystole (in severe cases) 1

Non-Cardiac Manifestations

• Gastrointestinal symptoms:

  • Anorexia 1
  • Nausea 1
  • Vomiting 1

• Neurological symptoms:

  • Visual disturbances (yellow-green halos around objects, blurred vision) 1
  • Disorientation 1
  • Confusion 1
  • Altered mental status 3

• General symptoms:

  • Fatigue 4
  • Weakness 4

Severity Classification

Mild Toxicity

• Isolated ectopic beats 1
• Mild gastrointestinal or neurological symptoms 1
• Serum digoxin levels usually <2 ng/mL 1

Severe Toxicity

• Sustained ventricular arrhythmias 1
• Advanced AV block 1
• Asystole 1
• Serum digoxin levels often >2 ng/mL, though toxicity can occur at lower levels with predisposing factors 1

Risk Factors for Toxicity

• Hypokalemia 1
• Hypomagnesemia 1
• Hypothyroidism 1
• Renal dysfunction 1
• Advanced age 1
• Low lean body mass 1
• Drug interactions (amiodarone, clarithromycin, erythromycin, verapamil, quinidine, itraconazole, cyclosporine) 1

Diagnostic Considerations

The diagnosis of digitalis toxicity is established by the combination of:

1. Characteristic rhythm disturbances
2. Ancillary symptoms (visual disturbances, nausea, changes in mentation)
3. Elevated serum digoxin concentrations (though toxicity can occur at therapeutic levels) 1

Important Caveats

• Multiple simultaneous arrhythmias strongly suggest digitalis toxicity 2
• Toxicity can occur even at therapeutic serum levels, especially with predisposing factors 1
• Overt toxicity is commonly associated with serum levels >2 ng/mL, but can occur at lower levels 1
• The presence of both AV block and increased automaticity (e.g., PVCs) is highly suggestive of digitalis toxicity 1
• Visual disturbances (especially yellow-green halos) are relatively specific for digitalis toxicity 3

Early recognition of these symptoms is crucial for prompt management and prevention of life-threatening complications associated with digitalis toxicity.