Clinical features
- GIT: Nausea, vomiting, anorexia, diarrhoea
- Visual: Blurred vision, yellow/green discolouration, haloes
- CVS: Palpitations, syncope, dyspnoea
- CNS: Confusion, dizziness, delirium, fatigue
Electrocardiographic Features
- Digoxin can cause a multitude of dysrhythmias, due to increased automaticity (increased intracellular calcium) and decreased AV conduction (increased vagal effects at the AV node)
- The classic dysrhythmia associated with digoxin toxicity is the combination of a supraventricular tachycardia (due to increased automaticity) with a slow ventricular response (due to decreased AV conduction), e.g. ’atrial tachycardia with block’.
Other arrhythmias associated with digoxin toxicity are:
- Frequent PVCs (the most common abnormality), including ventricular bigeminy and trigeminy
- Sinus bradycardia or slow AF
- 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
ECG Examples
Example 1 – Bigeminy
- Sinus rhythm with frequent PVCs in a pattern of ventricular bigeminy
Example 2 – “Paroxysmal” atrial tachycardia with block
- Atrial tachycardia with high-grade AV block and PVCs
Example 3 – Regularised AF
- Coarse atrial fibrillation with 3rd degree AV block and a junctional escape rhythm.
Example 4 – Regularised AF
- Another example of regularised AF.
Example 5 – “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.
Example 6 – Atrial flutter with AV block
- Atrial flutter with a slow ventricular rate due to digoxin toxicity.
Example 7 – Bidirectional VT
- This is a great example of bidirectional ventricular tachycardia. There is a broad complex tachycardia with a frontal-plane axis that alternates by 180 degrees with each successive beat.
Related Topics
Further Reading
- ECG BASICS – Waves, Intervals, Segments and Clinical Interpretation
- ECG CLINICAL CASES – Your favourite ECG’s placed in clinical context with a challenging Q&A approach
- ECG and Cardiology Eponymous Syndromes – Cheats guide to eponymous emancipation
- ECG Reference Sites on the WEB – the best of the rest
Author Credits
References
- Chan TC, Brady WJ, Harrigan RA, Ornato JP and Rosen PR. ECG in Emergency Medicine and Acute Care. Elsevier 2005
- Mattu A, Brady W. ECGs for the Emergency Physician 2, BMJ Books 2008.
- Murray L, Daly F, Little M, Cadogan M. Toxicology Handbook (second edition). Elsevier, 2011.
About Edward Burns
