Acute and chronic digitalis toxicity: presentation and treatment

Chronic Digoxin Toxicity: An Evaluation of Digoxin-Specific Antibodies and Other Management Options

Chronic digoxin toxicity comprises the bulk of digoxin poisonings and can be more difficult to manage than acute intoxications. A 60-year-old lady presented with severe chronic digoxin toxicity after ingesting digoxin 250mcg twice a day (BD) for two weeks. Due to hemodynamic instability on presentation, she was treated with digoxin-specific antibodies and admitted to the coronary care unit. This case of chronic digoxin toxicity did not respond to digoxin-specific antibodies and required intensive cardiac therapy with isoprenaline and intravenous electrolyte replacement, highlighting the complexities in the management of toxicity. Our patient has since recovered and remains stable. There are newer, novel therapies being trialed for the treatment of digoxin toxicity, including dextrose-insulin infusions, therapeutic plasma exchange, and rifampicin, but these require more research and investigation in this cohort of patients.

Mechanisms, manifestations, and management of digoxin toxicity in the modern era

Because of the common use of digoxin and because of its narrow therapeutic index, digoxin toxicity has been prevalent historically and, therefore, most clinicians are well aware of the classical dose/concentration-related signs and symptoms of toxicity. Yet, in the modern era the incidence of digoxin toxicity has been declining for a variety of reasons, including a new (lower) therapeutic range, the development of more effective drug therapies for heart failure, and more accurate dosing methods. In addition, digoxin toxicity, once commonly fatal, can now be quickly and effectively treated by the emergency administration of antidigoxin Fab fragments. Indeed, it may be possible to expand the use of Fab fragments to select patients with non-life-threatening digoxin toxicity, in order to save costs and improve patient comfort. Most cases of digoxin toxicity are caused by inappropriately high dosages, which are usually prescribed in the setting of renal dysfunction, while other cases can be attributed to system errors such as multiple prescriptions, poor patient counseling, or errors in transcribing. With modern computerized prescribing systems, such as direct physician order entry and prompts that alert the clinician to the potential for error, it is possible to decrease the incidence of digoxin toxicity even further. A realistic goal is to nearly eradicate once commonplace digoxin toxicity or at least make its occurrence a rare event.

Electrocardiographic manifestations: digitalis toxicity

Toxicity from the digitalis family of cardiac glycoside medications remains common. Successful treatment depends on early recognition; however, the diagnosis of potentially life-threatening toxicity remains difficult because the clinical presentation is often nonspecific and subtle. The hallmark of cardiac toxicity is increased automaticity coupled with concomitant conduction delay. Though no single dysrhythmia is always present, certain aberrations such as frequent premature ventricular beats, bradydysrhythmias, paroxysmal atrial tachycardia with block, junctional tachycardia, and bidirectional ventricular tachycardia are common. Treatment depends on the clinical condition rather than serum drug level. Management varies from temporary withdrawal of the medication to administration of digoxin-specific Fab fragments for life-threatening cardiovascular compromise.

Recognition and management of digitalis intoxication: implications for emergency medicine

Digitalis intoxication is among the most common serious adverse drug reactions in clinical medicine. While the recent development of a radioimmunoassay to accurately measure serum concentrations of digoxin has been of assistance, digitalis intoxication remains a difficult diagnosis to make with certainty. The difficulty in diagnosing digitalis intoxication arises from the nonspecificity of its associated signs and symptoms. The most common symptoms include fatigue, weakness, nausea, and anorexia. These symptoms can occur with many illnesses other than digitalis intoxication. Similarly, the electrocardiographic disturbances caused by cardiac glycosides may be nondiagnostic. The arrhythmias commonly associated with digitalis toxicity are often nonspecific and can be a reflection of the patient's underlying heart disease. The measurement of serum digoxin levels is useful, but studies have demonstrated overlap of the levels between groups with and without toxicity. Due to the modulation of the cardiac effects of digitalis glycosides by such clinical variables as underlying myocardial or renal disease, electrolyte and acid-base imbalances, and other factors, the correlation of toxicity with particular serum digoxin concentrations may vary. Because of the inherent difficulties in confirming the diagnosis of digitalis intoxication in some cases, digoxin-specific Fab antibodies may play a role as a diagnostic tool. Certainly, digoxin-specific Fab antibodies play a significant part in the treatment of digitalis intoxication. Fab antibodies have been successfully used to reverse the effects of digoxin, digitoxin, and oleander poisoning. These antibodies are useful in the treatment of acute and chronic digitalis intoxication in all age groups, including geriatric and pediatric populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute digoxin overdose: use of digoxin-specific antibody fragments

An acute ingestion of 6 to 7 mg digoxin as a suicidal gesture in a 76-year-old man with chronic heart disease is presented. The patient arrived in the emergency department approximately 5 hours after ingestion with a normal serum potassium and increasing numbers of multifocal premature ventricular contractions. Digoxin-specific antibody fragments were administered. The patient developed ventricular tachycardia and ventricular fibrillation and was eventually stabilized 35 minutes after the Fab fragments were infused. A review of the pharmacology and indications for use of digoxin-immune Fab fragments is also presented.

Fatal digoxin poisoning: an unsuccessful resuscitation with use of digoxin-immune Fab

A 1-month-old infant suffered cardiac arrest shortly after presentation to the emergency department. The child had a history of heart disease treated with digoxin. The infant died despite intensive resuscitative efforts, including the use of digoxin-specific Fab antibodies. A brief discussion of this case and the use of digoxin-specific antibodies is presented.

Digoxin levels in prehospital sudden-death syndrome

Digitalis toxicity is common and has been associated with ventricular dysrhythmias. Digoxin levels in patients who suffer prehospital sudden death have never been studied. This study measured digoxin levels in a population of sudden-death patients. During the 15-week study period, 252 patients in cardiac arrest were seen by an urban paramedic system. During daytime hours, paramedics were requested to obtain a blood sample from sudden-death patients; the samples were subsequently analyzed for digoxin by means of radioimmunoassay. Thirty-nine patients had measured digoxin levels drawn; 28 (71.8%) were in the therapeutic range (0.5-2.1 ng/mL), and four (10.2%) were in the toxic range (greater than 2.1 ng/mL). The patients with toxic dogoxin levels and those with nontoxic levels had similar resuscitation rates (50.0% vs. 34.3%, P = NS), but none were found in ventricular fibrillation. Emergency medical services personnel should consider digoxin toxicity as a potential etiology of arrest.

Herbal poisoning: a case report of a fatal yellow oleander poisoning from the Solomon Islands

A fatal yellow oleander herbal poisoning is reported in a 2 1/2-year-old Melanesian boy, who had persistent vomiting,bradycardia caused by complete heart block, hyperkalemia and cardiac glycosides detected in his serum. This is one of the few recognized clinical pictures of illness from herbal poisoning, yet herbal poisoning in infants in some Pacific and African countries is common and has a high mortality.

Acute massive digoxin overdose: survival without use of digitalis-specific antibodies

Acute massive digoxin overdose may result in life-threatening arrhythmias, with reported mortality of up to 20% prior to the introduction of digitalis-specific antibodies. Digitalis-specific Fab antibody fragments remain under experimental protocol and are not widely available. Interpretation of serum digoxin levels and indications for the use of Fab are not clearly established. The authors report a case of massive digoxin overdose in an 18-month-old child with the highest reported digoxin level (48 ng/ml) with which a victim survived without the need for Fab administration. She developed only mild manifestations of digitalis intoxication, and her serum potassium never exceeded 5.2 mEq/l. Her course may be explained by the distribution kinetics of digoxin, which follows a two-compartment model, and the relative resistance of children to digitalis intoxication. This case emphasizes the need for better criteria than the digoxin level for the administration of Fab. The serum potassium concentration, which is usually elevated in acute type digitalis intoxication, may be a better predictor of the need for Fab in acute massive digitalis ingestion.

Therapeutic and toxic effects of digitalis: William Withering, 1785

William Withering's classic description of the effects of digitalis was published in 1785. Although he was largely unaware of the drug's cardiac effects, he successfully treated many patients with congestive heart failure. He also recorded many striking examples of digitalis toxicity. This review highlights Withering's experience with "the foxglove," and summarizes modern concepts of digitalis efficacy and toxicity.

Acute digitalis poisoning: the role of intravenous magnesium sulfate

Acute digitalis poisoning is a complex emergency with a reported mortality rate of 3% to 25%. In severe overdose, the sodium, potassium-adenosine triphosphatase system is severely inhibited, leading to cardiac dysrhythmias and an elevation of the serum potassium. Magnesium, a cofactor regulating this ion transport system, can successfully treat acute digitalis-induced rhythm disturbances and restore the transmembrane potassium gradient. This paper discusses the cellular mechanism involved in digitalis toxicity and reviews the literature concerning the use of magnesium in acute cardiac glycoside poisoning.

Oleander tea: herbal draught of death

A woman died after drinking herbal tea prepared from oleander (Nerium oleander) leaves. This case demonstrates the cross-reactivity between the cardiac glycosides in oleander and the digoxin radioimmunoassay. Digoxin-specific Fab antibody fragments have not been used in oleander poisoning, but these might prove to be lifesaving. Treatment of oleander toxicity is aimed at controlling arrhythmias and hyperkalemia; inactivation of the Na-K ATPase pump, however, can make treatment difficult.