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Home | ECG Library | Digoxin Effect

Digoxin Effect

by Dr Ed Burns, last update February 6, 2019

↪  ECG Library Homepage

ECG Features demonstrating the Digoxin Effect

Digoxin effect refers to the presence on the ECG of:

  • Downsloping ST depression with a characteristic “Salvador Dali sagging” appearance
  • Flattened, inverted, or biphasic T waves.
  • Shortened QT interval.

Other Digoxin effect features

Additional ECG 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”!

Digoxin effect reverse tick salvador dali moustache

T-wave changes

The 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.

Digoxin Effect T waves

Mechanism

The ECG features of digoxin effect are seen with therapeutic doses of digoxin and are due to:

  • 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.


ECG Examples

Example 1
Digoxin effect 1

Digoxin effect:

  • 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“.

Example 2
Digoxin effect Atrial Fibrillation 2

Digoxin effect:

  • Sagging ST segments are most evident in the lateral leads V4-6, I and aVL.

Example 3

Digoxin effect AF fibrillatory waves V1 2

Digoxin effect:

  • The sagging morphology is most evident in V6 and in the lead II rhythm strip.

Example 4
Digoxin effect 4

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.

Example 5
Digoxin effect and Digoxin toxicity

Digoxin effect:

  • Sagging ST depression is clearly evident in leads I, II, III, aVF and V5-6.
  • Frequent premature ventricular complexes (PVCs) suggest the possibility of digoxin toxicity.

Related Topics

  • Digoxin toxicity
  • The QT interval

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

Advanced Reading

  • 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

ECG LIBRARY 700

ECG LIBRARY

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About Dr Ed Burns

Dr Ed Burns . Emergency Physician in Pre-hospital and Retrieval Medicine in Sydney, Australia. He has a passion for ECG interpretation and medical education.

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