Digoxin Toxicity

ECG Features of Digoxin Toxicity

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

Pathophysiology

Digoxin can cause a multitude of dysrhythmias due to:

• Increased automaticity (increased intracellular calcium)
• Decreased AV conduction (increased vagal effects at the AV node)

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 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 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.

Related reading

• Digoxin effect
• Bidirectional VT

Advanced Reading

Online

• Wiesbauer F, Kühn P. ECG Mastery: Yellow Belt online course. Understand ECG basics. Medmastery
• Wiesbauer F, Kühn P. ECG Mastery: Blue Belt online course: Become an ECG expert. Medmastery
• Kühn P, Houghton A. ECG Mastery: Black Belt Workshop. Advanced ECG interpretation. Medmastery
• Rawshani A. Clinical ECG Interpretation ECG Waves
• Smith SW. Dr Smith’s ECG blog.
• Wiesbauer F. Little Black Book of ECG Secrets. Medmastery PDF

Textbooks

• Zimmerman FH. ECG Core Curriculum. 2023
• Mattu A, Berberian J, Brady WJ. Emergency ECGs: Case-Based Review and Interpretations, 2022
• Straus DG, Schocken DD. Marriott’s Practical Electrocardiography 13e, 2021
• Brady WJ, Lipinski MJ et al. Electrocardiogram in Clinical Medicine. 1e, 2020
• Mattu A, Tabas JA, Brady WJ. Electrocardiography in Emergency, Acute, and Critical Care. 2e, 2019
• Hampton J, Adlam D. The ECG Made Practical 7e, 2019
• Kühn P, Lang C, Wiesbauer F. ECG Mastery: The Simplest Way to Learn the ECG. 2015
• Grauer K. ECG Pocket Brain (Expanded) 6e, 2014
• Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric 6e, 2008
• Chan TC. ECG in Emergency Medicine and Acute Care 1e, 2004

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