Clinical features of Digoxin Toxicity
- GIT: Nausea, vomiting, anorexia, diarrhoea
- Visual: Blurred vision, yellow/green discolouration, haloes
- CVS: Palpitations, syncope, dyspnoea
- CNS: Confusion, dizziness, delirium, fatigue
ECG Features of Digoxin Toxicity
Digoxin can cause a multitude of dysrhythmias due to:
- increased automaticity (increased intracellular calcium)
- decreased AV conduction (increased vagal effects at the AV node)
The classic digoxin toxic dysrhythmia combines:
- supraventricular tachycardia (due to increased automaticity)
- slow ventricular response (due to decreased AV conduction)
Other common dysrhythmias associated with digoxin toxicity include:
- Frequent PVCs (the most common abnormality), including ventricular bigeminy and trigeminy
- Sinus bradycardia
- Slow Atrial Fibrillation
- Any type of AV block (1st degree, 2nd degree & 3rd degree)
- Regularised AF = AF with complete heart block and a junctional or ventricular escape rhythm
- Ventricular tachycardia, including polymorphic and bidirectional VT
- Sinus rhythm with frequent PVCs in a pattern of ventricular bigeminy
Paroxysmal atrial tachycardia with block
- Atrial tachycardia with high-grade AV block and PVCs
- Coarse atrial fibrillation with 3rd degree AV block and a junctional escape rhythm.
- Another example of regularised AF.
“Paroxysmal” atrial tachycardia with block and frequent PVCs
- This is a classic ECG of digoxin toxicity showing atrial tachycardia (P waves at 150 bpm), high-grade 2nd degree AV block (A:V ratio of 4:1) with frequent premature ventricular complexes.
Atrial flutter with AV block
- Atrial flutter with a slow ventricular rate due to digoxin toxicity.
Bidirectional Ventricular Tachycardia (VT)
- Example of Bidirectional VT.
- There is a broad complex tachycardia with a frontal-plane axis that alternates by 180 degrees with each successive beat.
LITFL Further Reading
- ECG Library Basics – Waves, Intervals, Segments and Clinical Interpretation
- ECG A to Z by diagnosis – ECG interpretation in clinical context
- ECG Exigency and Cardiovascular Curveball – ECG Clinical Cases
- 100 ECG Quiz – Self-assessment tool for examination practice
- ECG Reference SITES and BOOKS – the best of the rest
- Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric
- Wagner GS. Marriott’s Practical Electrocardiography 12e
- Chan TC. ECG in Emergency Medicine and Acute Care
- Rawshani A. Clinical ECG Interpretation
- Mattu A. ECG’s for the Emergency Physician
- Hampton JR. The ECG In Practice, 6e