Digoxin toxicity

Source: Wikipedia, the free encyclopedia.
Digoxin toxicity
Other namesDigoxin poisoning, digoxin overdose
digoxin-specific antibody fragments[2][1]
Frequency~2,500 cases per year (US)[2]

Digoxin toxicity, also known as digoxin poisoning, is a type of

irregular heartbeat, which can be either too fast or too slow.[1]

Toxicity may occur over a short period of time following an

electrocardiogram is a routine part of diagnosis.[2] Blood levels are only useful more than six hours following the last dose.[1]

digoxin-specific antibody fragments.[1] Its use is recommended in those who have a serious dysrhythmia, are in cardiac arrest, or have a potassium of greater than 5 mmol/L.[1] Low blood potassium or magnesium should also be corrected.[1] Toxicity may reoccur within a few days after treatment.[1]

In Australia in 2012 there were about 140 documented cases.[1] This is a decrease by half since 1994 as a result of decreased usage of digoxin.[1] In the United States 2500 cases were reported in 2011 which resulted in 27 deaths.[2] The condition was first described in 1785 by William Withering.[4]

Signs and symptoms

Digoxin toxicity is often divided into acute or chronic toxicity. In both of these toxicity, cardiac effects are of the greatest concern. With an acute ingestion, symptoms such as nausea, vertigo, and vomiting are prominent. On the other hand, nonspecific symptoms are predominant in chronic toxicity. These symptoms include fatigue, malaise, and visual disturbances.[5]

The classic features of digoxin toxicity are nausea, vomiting, abdominal pain, headache, dizziness, confusion, delirium, vision disturbance (blurred or

irregular heartbeat, ventricular tachycardia, ventricular fibrillation, sinoatrial block and AV block.[6]

Diagnosis

In individuals with suspected digoxin toxicity, a serum digoxin concentration, serum potassium concentration, creatinine, BUN, and serial electrocardiograms is obtained.[7]

ECG

An ECG showing digoxin toxicity with the classic "scooped out" ST segment

In digoxin toxicity, the finding of frequent premature ventricular beats (PVCs) is the most common and the earliest dysrhythmia.

ECG changes that suggest digoxin toxicity include bigeminal and trigeminal rhythms, ventricular bigeminy, and bidirectional ventricular tachycardia.[5]

Blood test

The level of digoxin for treatment is typically 0.5-2 ng/mL.[8] Since this is a narrow therapeutic index, digoxin overdose can happen. A serum digoxin concentration of 0.5-0.9 ng/mL among those with heart failure is associated with reduced heart failure deaths and hospitalizations.[9] It is therefore recommended that digoxin concentration be maintained in approximately this range if it is used in heart failure patients.

High amounts of the electrolyte potassium (K+) in the blood (hyperkalemia) is characteristic of digoxin toxicity.[6] Digoxin toxicity increases in individuals who have kidney impairment. This is most often seen in elderly or those with chronic kidney disease or end-stage kidney disease.[10]

Treatment

Digoxin immune Fab used to treat digoxin toxicity

The primary treatment of digoxin toxicity is

immunoglobulin fragments. This antidote has been shown to be highly effective in treating life-threatening signs of digoxin toxicity such as hyperkalemia, hemodynamic instability, and arrhythmias.[11] Fab dose can be determined by two different methods. First method is based on the amount of digoxin ingested whereas the second method is based on the serum digoxin concentration and the weight of the person.[10]

Other treatment that may be used to treat life-threatening arrhythmias until Fab is acquired are magnesium, phenytoin, and lidocaine. Magnesium suppresses digoxin-induced ventricular arrhythmias while phenytoin and lidocaine suppresses digoxin-induced ventricular automaticity and delay afterdepolarizations without depressing AV conduction. In the case of an abnormally slow heart rate (bradyarrhythmias), Atropine, catecholamines (isoprenaline or salbutamol), and/or temporary cardiac pacing can be used.[8]

References

  1. ^
    PMID 27041802
    .
  2. ^
    PMID 24883458. Archived
    from the original on 2014-05-14.
  3. PMID 16735690
    .
  4. ISBN 9781405172530. Archived
    from the original on 2017-09-10.
  5. ^
    PMID 11207409
    .
  6. ^
    PMID 12007081
    .
  7. ^ Dugdale, David. "Digitalis toxicity". MedlinePlus. Archived from the original on 1 November 2014. Retrieved 30 October 2014.
  8. ^
    PMID 3529634
    .
  9. PMID 16339157
    .
  10. ^
    S2CID 7538601
    .
  11. PMID 2188752
    .

External links

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