A complication of digitalis therapy, or an acute ingestion of digitalis.
Causes, incidence, and risk factors
Digitalis toxicity is the result of the body accumulating more digitalis than it can tolerate at that time. That can be caused by high levels of digitalis in the body, or it can be caused by "normal" levels but decreased tolerance by the body. Digitalis toxicity can occur from a single exposure, chronic over-medication, or can be precipitated with normal or therapeutic blood levels of digitalis if other risks are present. Risks include taking digitalis medications such as digoxin or digitoxin, particularly if also taking medications that interact with digitalis such as quinidine, verapamil, amiodarone, and others. People with heart failure are commonly given diuretics ("water pills," medications to pull excess fluid from the body) along with digoxin. Many diuretics can cause potassium loss. Low levels of potassium in the body increases the risk of digitalis toxicity. Digitalis toxicity can also be precipitated by low levels of magnesium in the body. Reduced kidney function will cause digitalis to accumulate in the body rather than being disposed of normally through the urine. Therefore, any disorders that disrupt kidney functioning (including dehydration ) make digitalis toxicity more likely.
Signs and tests
The heart rate may be rapid or slow and it may be irregular.
ECG may show any of a variety of arrhythmias .
Serum levels of digoxin or digitoxin may be high or normal ( digoxin - test , digitoxin - test ).
A blood chemistry test to determines the levels of potassium and magnesium; creatinine and BUN are performed to evaluate kidney functioning.
Treatment
In an emergency, assist breathing as needed (see CPR ). Obtain professional medical assistance. Arrhythmias are treated according to which arrhythmia develops. If toxicity is from a recent, acute single exposure, gastric lavage (pumping the stomach) may be performed, and charcoal is given. Digitoxin levels may reduce with repeated doses of charcoal. Lavage is recommended over inducing vomiting because vomiting can aggravate slow heart rhythms. Medications such as digoxin specific antibodies may be prescribed. Hemodialysis may be required to reduce the levels of digitalis in the body.
Expectations (prognosis)
The outcome varies depending on the extent of toxicity and arrhythmias that develop.
Prevention
Digitalis levels should be monitored regularly when on digitalis medications. Blood chemistries should also be monitored to detect conditions that make digitalis toxicity more common. Potassium supplements may be prescribed if diuretics and digitalis are used simultaneously, or a "potassium sparing" diuretic may be prescribed.