Digoxin Effect

Electrocardiographic Features

Digoxin effect refers to the presence on the ECG of:

  • Downsloping ST depression with a characteristic “sagging” appearance (see below).
  • Flattened, inverted, or biphasic T waves.
  • Shortened QT interval.

Other features of digoxin effect

  • 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).

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”!

Click image for source

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. 

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:

  • 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:

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

 

Example 3

Another example of digoxin effect:

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

 

Example 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:

 

Related Topics

Further Reading

Author Credits

References

  • Chan TC, Brady WJ, Harrigan RA, Ornato JP, Rosen P. ECG in Emergency Medicine and Acute Care. Elsevier Mosby 2005.
  • Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice (6th edition), Saunders 2008.
  • Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.
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  1. [...] Abstract This case report from Oman describes at 66-year-old woman (inexplicably described as “elderly”) who presented to hospital with one day of nausea, vomiting, abdominal distress, and palpitations. Her medications included furosemide, spironolactone, digoxin, carvedilol, lisinopril, metformin, and calcium. Initial EKGs showed evidence of junctional tachycardia and digoxin effect. [...]

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