ECG Features demonstrating the Digoxin Effect
Other Digoxin effect features
- Mild PR interval prolongation of up to 240 ms (due to increased vagal tone).
- Prominent U waves.
- Peaking of the terminal portion of the T waves.
- J point depression (usually in leads with tall R waves).
QRS complex / ST segment changes
- The morphology of the QRS complex / ST segment is variously described as either “slurred”, “sagging” or “scooped” and resembling either a “reverse tick”, “hockey stick” or (my personal favourite) “Salvador Dali’s moustache”!
- TThe most common T-wave abnormality is a biphasic T wave with an initial negative deflection and terminal positive deflection. This is usually seen in leads with a dominant R wave (e.g. V4-6). The first part of the T wave is typically continuous with the depressed ST segment. The terminal positive deflection may be peaked, or have a prominent U wave superimposed upon it.
- Shortening of the atrial and ventricular refractory periods — producing a short QT interval with secondary repolarisation abnormalities affecting the ST segments, T waves and U waves.
- Increased vagal effects at the AV node — causing a prolonged PR interval.
NB. The presence of digoxin effect on the ECG is not a marker of digoxin toxicity. It merely indicates that the patient is taking digoxin.
- This is the classic picture of digoxin effect with the “sagging” ST segments and T waves taking on the appearance of “Salvador Dali’s moustache”.
This is a slight variation on the classic digoxin pattern:
- There is still downsloping ST depression but it is slightly more angular, in comparison to the “sagging” ST segments from the previous example.
- Also, there is J-point depression in V4-6, which mimics the appearance of left ventricular hypertrophy.
- The short QT interval, the “sagging” appearance in the inferior leads and the lack of voltage criteria for LVH indicates that this is digoxin effect rather than LVH.
- Brady WJ, Truwit JD. Critical Decisions in Emergency and Acute Care Electrocardiography
- Hampton, JR. The ECG In Practice, 6e
- Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice: Adult and Pediatric, 6e
- Wagner, GS. Marriott’s Practical Electrocardiography 12e
- Chan, TC. ECG in Emergency Medicine and Acute Care
- Mattu, A. ECG’s for the Emergency Physician
LITFL Further Reading
- ECG BASICS — Waves, Intervals, Segments and Clinical Interpretation
- ECG A to Z by diagnosis –alphabetical diagnostic approach to the ECG
- ECG CLINICAL CASES — ECG’s placed in clinical context with a challenging Q&A approach
- 100 ECG Quiz — Self-assessment tool for examination practice
- ECG Reference SITES and BOOKS — the best of the rest
- LITFL ECG IMAGE Database — Searchable database of LITFL ECG’s
- ECG and Cardiology Eponymous Syndromes — Cheats guide to eponymous emancipation
- ECG Exam Template — a framework for answering ECG exam questions.