Management of Digoxin Toxicity
Digoxin-specific antibody fragments (digoxin-Fab) are the first-line treatment for digoxin toxicity with life-threatening manifestations, including serious arrhythmias, hyperkalemia, or hemodynamic compromise. 1
Clinical Manifestations
Cardiac Manifestations
- Arrhythmias including enhanced atrial, junctional, or ventricular automaticity often combined with atrioventricular block 2
- Ventricular tachycardia that is fascicular or bidirectional in origin is highly suggestive of digoxin toxicity 2
- Severe digoxin overdose can cause hyperkalemia and cardiac standstill 2
Non-Cardiac Manifestations
- Gastrointestinal: anorexia, nausea, and vomiting 2
- Neurological: changes in mentation/confusion, visual disturbances (blurred or yellow vision) 2
Diagnosis
- Diagnosis is established by the combination of characteristic rhythm disturbances, ancillary symptoms, and elevated serum concentrations 2
- Toxicity is commonly associated with serum digoxin levels >2 ng/mL, but can occur at lower levels within the therapeutic range (0.5-1.2 ng/mL) 2
- Hyperkalemia (>5.0 mEq/L) is a marker of severity in acute digoxin poisoning 3
Management Algorithm
Step 1: Assess Severity
- Mild toxicity: Minor symptoms without significant arrhythmias or hemodynamic compromise 3
- Moderate to severe toxicity: Serious arrhythmias, hyperkalemia >5.0 mEq/L, or hemodynamic instability 3
Step 2: Initial Management
- Discontinue digoxin immediately in all cases 4
- Monitor cardiac rhythm continuously 4
- Check serum potassium, magnesium, and calcium levels 3
- Maintain serum potassium between 4.0-5.5 mmol/L 4
Step 3: Treatment Based on Severity
For Mild Toxicity
- Discontinuation of digoxin may be all that is required 4
- Correct electrolyte abnormalities, particularly hypokalemia or hypomagnesemia 2
For Moderate to Severe Toxicity
Administer digoxin-specific antibody fragments (digoxin-Fab) for: 1
- Life-threatening arrhythmias
- Serum digoxin concentrations >4 ng/mL
- Hyperkalemia >5.0 mEq/L
- Hemodynamic instability
Dosing of digoxin-Fab:
For Specific Arrhythmias While Awaiting Digoxin-Fab
Bradyarrhythmias: 1
- Atropine may be reasonable
- Temporary pacing may be needed (though complications are common)
Ventricular dysrhythmias: 1
- Lidocaine, phenytoin may be reasonable until digoxin-Fab can be administered
Important Considerations
Electrolyte Management
- Hypokalemia increases the risk of digoxin toxicity - correct before administering digoxin 2
- In acute massive overdose, hyperkalemia may occur and should not be treated with potassium supplements 4
- Hyperkalemia caused by massive digitalis toxicity is best treated with digoxin-Fab 4
Ineffective Treatments
- Hemodialysis, hemofiltration, hemoperfusion, or plasmapheresis are not recommended for digoxin toxicity 1
Monitoring After Treatment
- Digoxin concentration monitoring becomes unreliable after antidigoxin antibody administration 3
- Monitor for potential rebound toxicity after digoxin-Fab treatment 5
Resumption of Therapy
- If digoxin therapy must be continued after levels normalize, use lower doses (0.125 mg daily or every other day) for patients with risk factors 2
- Avoid loading doses when reinitiating therapy 2
Risk Factors for Digoxin Toxicity
- Advanced age and low lean body mass 2
- Renal dysfunction 2
- Hypothyroidism, hypokalemia, and hypomagnesemia 2
- Concomitant medications that increase digoxin levels: amiodarone, clarithromycin, erythromycin, itraconazole, cyclosporine, verapamil, quinidine, propafenone, and dronedarone 2
By following this algorithm, clinicians can effectively manage digoxin toxicity while minimizing morbidity and mortality associated with this potentially life-threatening condition.