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Digitalis Toxicity

Digitalis Poisoning

Digitalis toxicity may occur either acute or chronic. Digitalis is a cardiac glycoside frequently used in the therapy of chronic heart failure, reentrant supraventricular tachycardia and atrial fibrillation.


Presentation

In cases of pediatric digitalis, majority are as a result of unintentional ingestion. Therefore it is necessary to get a good social history with emphasis on available medications and the extent of home child proofing.

For patients who have been on digoxin for some time, the addition of a new drug to their medication must be noted. Some drugs that can increase the level of digoxin include: Paroxetine, tetracycline, erythromycin, Dilitiazem and paroxetine [5]. On the other hand, rifampin increases the metabolism of digitalis through enzymatic simulation. This helps in decreasing the digoxin level.

Symptoms of digitalis toxicity that affect the central nervous system include: drowsiness, lethargy, fatigue, neuralgia, headache, dizziness, seizures, hallucinations, confusion or giddiness, paresthesias and neuropathic pain.

One of the early signs of digitalis toxicity is visual aberration. Yellow-green distortion is the most common but red, white, blue, brown distortions can also occur [6]. Drug intoxication can also bring about the following: photopsia, photophobia, snowy vision, transient amblyopia or scotomata, yellow halos around lights (xanthopsia) and decreased visual acuity.

Some gastrointestinal symptoms that can be seen with acute or chronic toxicity include the following: Weight loss, anorexia, vomiting, nausea, abdominal pain, diarrhea and mesenteric ischemia.

Some cardiac symptoms of the condition include: syncope, shortness of breath, palpitations, hypotension, swelling of lower extremities and Bradycardia

Congestive Heart Failure
  • They have been the treatment of choice for congestive heart failure for many decades, and recently their clinical utility has been redefined.[ncbi.nlm.nih.gov]
  • heart failure (CHF) and underlying coronary atherosclerosis who are not receiving a cardiac glycoside.[ncbi.nlm.nih.gov]
  • Digitek – also known as “digoxin” – is used by very ill patients with congestive heart failure or abnormal heart rhythms. In April 2008, Digitek tablets were recalled by the manufacturer, Actavis Totowa.[attorneystrialgroup.com]
  • There were only 14 patients with adverse events considered to possibly or probably have been caused by Fab; the most common events were rapid development of hypokalemia and exacerbation of congestive heart failure.[circ.ahajournals.org]
  • It’s often used to treat congestive heart failure and is also used to treat certain arrhythmias Toxicity to digitalis can be associated with heart block.[allnursingnotes.com]
Fatigue
  • Digoxin toxicity Cardiology Clinical findings of digoxin overdose Clinical Loss of appetite, N&V, defects in color vision–reds and greens, or seeing halos around lights, psychotic changes, weakness, fatigue, or dizziness; new onset of arrhythmias typical[medical-dictionary.thefreedictionary.com]
  • Symptoms of digitalis toxicity that affect the central nervous system include: drowsiness, lethargy, fatigue, neuralgia, headache, dizziness, seizures, hallucinations, confusion or giddiness, paresthesias and neuropathic pain.[symptoma.com]
  • Other symptoms include fatigue, drowsiness, general muscle weakness, and visual disturbances such as blurring of vision, yellow-green or white halos around visual images, light flashes, photophobia, and diplopia.[medical-dictionary.thefreedictionary.com]
  • Neurologic symptoms—including headache, fatigue, confusion, delirium, seizures, or visual color disturbance—are mediated by the effects of excess digitalis on the chemoreceptors of the medulla of the brain.[calsprogram.org]
  • Pathophysiology Digoxin Inotropic NA /K ATPase pump causing in intracellular Ca , Na and in intracellular K Chronotropic Slows conduction in AV node (but increased spontaneous firing by Purkinje tissues) Toxic effect mainly ATPase pump effects History Fatigue[emed.ie]
Nausea
  • In a review of the records of 81 patients with the discharge diagnosis of digitalis toxicity, I found a preponderance of very old patients, many of whom had anorexia, nausea, and prerenal azotemia.[ncbi.nlm.nih.gov]
  • Some gastrointestinal symptoms that can be seen with acute or chronic toxicity include the following: Weight loss, anorexia, vomiting, nausea, abdominal pain, diarrhea and mesenteric ischemia.[symptoma.com]
  • Digitalis toxicity can cause a heart attack, stroke, kidney failure, nausea, vomiting, dizziness, low blood pressure and an unstable or slow heart rate. Digitalis toxicity can also lead to death.[attorneystrialgroup.com]
  • Signs of toxicity include nausea, vomiting, and an irregular heartbeat. To prevent DT, monitor your intake of digitalis to make sure you’re not taking too much of the medication.[healthline.com]
  • Nausea and vomiting, sometimes with abdominal pain and increased salivation, usually appear 1 to 2 days later.[medical-dictionary.thefreedictionary.com]
Vomiting
  • Nausea and vomiting, sometimes with abdominal pain and increased salivation, usually appear 1 to 2 days later.[medical-dictionary.thefreedictionary.com]
  • Some gastrointestinal symptoms that can be seen with acute or chronic toxicity include the following: Weight loss, anorexia, vomiting, nausea, abdominal pain, diarrhea and mesenteric ischemia.[symptoma.com]
  • Digitalis toxicity can cause a heart attack, stroke, kidney failure, nausea, vomiting, dizziness, low blood pressure and an unstable or slow heart rate. Digitalis toxicity can also lead to death.[attorneystrialgroup.com]
  • Signs of toxicity include nausea, vomiting, and an irregular heartbeat. To prevent DT, monitor your intake of digitalis to make sure you’re not taking too much of the medication.[healthline.com]
  • Methods to cause vomiting are usually not done because vomiting can worsen slow heart rhythms. In severe cases, medicines called digoxin-specific antibodies may be prescribed. Dialysis may be needed to reduce the level of digitalis in the body.[medlineplus.gov]
Diarrhea
  • Some gastrointestinal symptoms that can be seen with acute or chronic toxicity include the following: Weight loss, anorexia, vomiting, nausea, abdominal pain, diarrhea and mesenteric ischemia.[symptoma.com]
  • The patient is advised about conditions such as diarrhea, which may deplete the body of potassium or contribute to dehydration and renal insufficiency.[medical-dictionary.thefreedictionary.com]
  • Symptoms of Digitalis toxicity include: nausea, vomiting, diarrhea, loss of appetite, confusion, heart palpitations, irregular heartbeat, halos or rings of light around objects, and blind spots or blurred vision.[attorneystrialgroup.com]
  • Symptoms of digitalis include the following: Vomiting Diarrhea Irregular pulse Nausea Loss of appetite Palpitations Confusion Visual changes If you or someone you know is taking Digitek and experiences any of these symptoms, it is important to see a doctor[yourlegalguide.com]
  • Clinical manifestations are nonspecific but usually include gastrointestinal events (nausea, vomiting, diarrhea, and abdominal pain) along with circulatory effects (hemodynamic instability, dizziness or lightheadedness, and syncope).[dialnet.unirioja.es]
Abdominal Pain
  • Some gastrointestinal symptoms that can be seen with acute or chronic toxicity include the following: Weight loss, anorexia, vomiting, nausea, abdominal pain, diarrhea and mesenteric ischemia.[symptoma.com]
  • Clinical manifestations are nonspecific but usually include gastrointestinal events (nausea, vomiting, diarrhea, and abdominal pain) along with circulatory effects (hemodynamic instability, dizziness or lightheadedness, and syncope).[dialnet.unirioja.es]
  • Nausea and vomiting, sometimes with abdominal pain and increased salivation, usually appear 1 to 2 days later.[medical-dictionary.thefreedictionary.com]
  • The commonest symptoms and ECG signs in the subtherapeutic group were abdominal pain and atrial fibrillation (16.4% and 12.6%) respectively.[omicsonline.org]
  • Acute ingestion: GI symptoms (anorexia, nausea, vomiting, abdominal pain), neurologic manifestations of confusion and weakness Chronic toxicity: Less GI symptoms, more prominent neurologic manifestations (lethargy, fatigue, delirium, confusion, disorientation[ucsfmed.wordpress.com]
Loss of Appetite
  • Digoxin toxicity Cardiology Clinical findings of digoxin overdose Clinical Loss of appetite, N&V, defects in color vision–reds and greens, or seeing halos around lights, psychotic changes, weakness, fatigue, or dizziness; new onset of arrhythmias typical[medical-dictionary.thefreedictionary.com]
  • Symptoms of Digitalis toxicity include: nausea, vomiting, diarrhea, loss of appetite, confusion, heart palpitations, irregular heartbeat, halos or rings of light around objects, and blind spots or blurred vision.[attorneystrialgroup.com]
  • Symptoms of digitalis include the following: Vomiting Diarrhea Irregular pulse Nausea Loss of appetite Palpitations Confusion Visual changes If you or someone you know is taking Digitek and experiences any of these symptoms, it is important to see a doctor[yourlegalguide.com]
  • Some early warning signs of overdose are confusion, loss of appetite, nausea, vomiting, diarrhea, or vision problems.[mayoclinic.org]
  • Over time, a patient may begin to experience loss of appetite. Difficulties linked with blood have also been related with digoxin toxicity.[primehealthchannel.com]
Tachycardia
  • 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[ncbi.nlm.nih.gov]
  • ., sinus bradycardia, atrioventricular block, nonparoxysmal atrioventricular junctional tachycardia, and ventricular tachycardia.[ncbi.nlm.nih.gov]
  • The electrocardiogram revealed supraventricular bidirectional tachycardia, a rare but characteristic arrhythmia associated with digitalis toxicity. Upon withdrawal of digoxin, the clinical and ECG signs disappeared.[ncbi.nlm.nih.gov]
  • Atrial tachycardia with block is less specific and less frequent.[ncbi.nlm.nih.gov]
  • But when rapid control of the ventricular rate is required to arrhythmias such as atrial fibrillation, atrial flutter, or paroxysmal atrial tachycardia, a slow infusion of verapamil is the agent of choice.[ncbi.nlm.nih.gov]
Hypotension
  • Some cardiac symptoms of the condition include: syncope, shortness of breath, palpitations, hypotension, swelling of lower extremities and Bradycardia In patients with possible digitalis toxicity studies generally carried out include: Renal function studies[symptoma.com]
  • […] children Chronic Digoxin Toxicity with significant dysrhythmia or Hyperkalemia Dosing One vial or 40 mg binds 0.5 mg Digoxin Acute toxicity: 5 vials (repeat as needed) Chronic toxicity: 3-6 vials for adults (1-2 for children) Adverse effects Postural Hypotension[fpnotebook.com]
  • These may vary from nausea, vomiting and hypotension to more subtle non-specific symptoms.[btgplc.com]
  • METABOLIC: hyperkalaemia (early sign of significant toxicity) CVS: enhanced automaticity (atrial tachycardias (e.g. flutter, AF) with AV block, VF, VT, ventricular ectopic beats), bradyarrhythmias (Conduction delays / blocks, slow or regularised AF), hypotension[lifeinthefastlane.com]
  • […] patients) Nausea Vomiting Abdominal pain Diarrhea Mesenteric ischemia (a rare complication of rapid IV infusion) Cardiac symptoms Cardiac symptoms include the following: Palpitations Shortness of breath Syncope Swelling of lower extremities Bradycardia Hypotension[emedicine.medscape.com]
Ventricular Bigeminy
  • Rhythms that especially suggest digitalis toxicity include paroxysmal atrial tachycardia with block, non-paroxysmal accelerated junctional tachycardia, bi-directional VT, new onset ventricular bigeminy, and regularized AF.[calsprogram.org]
  • Most common finding: PVCs Other arrhythmias: bradycardia, atrial tachyarrhythmias with AV block, ventricular bigeminy, junctional rhythm, various degrees of AV nodal blockade, VT, VF Bidirectional ventricular tachycardia is encountered in rare instances[ucsfmed.wordpress.com]
  • Other ECG changes that suggest digoxin toxicity include bigeminal and trigeminal rhythms, ventricular bigeminy, and bidirectional ventricular tachycardia. [5] Blood test [ edit ] The level of digoxin for treatment is typically 0.5-2 ng/mL. [8] Since this[en.wikipedia.org]
Slow Pulse
Irregular Heart Rhythm
  • How well a person does depends on the severity of the toxicity and if it has caused an irregular heart rhythm. Call your provider if you are taking a digitalis medicine and you have symptoms of toxicity.[medlineplus.gov]
Muscle Weakness
  • Other symptoms include fatigue, drowsiness, general muscle weakness, and visual disturbances such as blurring of vision, yellow-green or white halos around visual images, light flashes, photophobia, and diplopia.[medical-dictionary.thefreedictionary.com]
Blurred Vision
  • Symptoms of Digitalis toxicity include: nausea, vomiting, diarrhea, loss of appetite, confusion, heart palpitations, irregular heartbeat, halos or rings of light around objects, and blind spots or blurred vision.[attorneystrialgroup.com]
  • Chronotropic Slows conduction in AV node (but increased spontaneous firing by Purkinje tissues) Toxic effect mainly ATPase pump effects History Fatigue Palpitations, DOE rare Pre-syncope or light headed Confusion Changes in colour vision Diplopia or blurred[emed.ie]
  • Here are some of the signs and symptoms of digitalis toxicity: includes: Confusion Nausea, vomiting, diarrhea Blurred Vision Halos or rings of light around objects It is important for the NCLEX to know that clients with digitalis toxicity would often[allnursingnotes.com]
  • Digoxin toxicity Synonyms Digoxin poisoning, digoxin overdose Drawings of Digitalis purpurea Specialty Emergency medicine Symptoms vomiting, loss of appetite, confusion, blurred vision, changes in color perception, decreased energy [1] Complications Heart[en.wikipedia.org]
  • Lack of appetite, nausea, vomiting, or diarrhea Headache, confusion, anxiety, or hallucinations Restlessness, weakness, or depression Changes in vision such as blurred vision or seeing halos around bright objects A fast, slow, or irregular heartbeat,[drugs.com]
Photophobia
  • Drug intoxication can also bring about the following: photopsia, photophobia, snowy vision, transient amblyopia or scotomata, yellow halos around lights (xanthopsia) and decreased visual acuity.[symptoma.com]
  • Other symptoms include fatigue, drowsiness, general muscle weakness, and visual disturbances such as blurring of vision, yellow-green or white halos around visual images, light flashes, photophobia, and diplopia.[medical-dictionary.thefreedictionary.com]
  • […] confusion and weakness Chronic toxicity: Less GI symptoms, more prominent neurologic manifestations (lethargy, fatigue, delirium, confusion, disorientation) Visual changes are varied and may include chromatopsia (alterations in color vision), diplopia, photophobia[ucsfmed.wordpress.com]
  • Photophobia can also occur with digoxin toxicity. A case of severe digoxin toxicity with visual disturbances has been reported recently in a 91 year old female [5].[cardiophile.org]
  • Drug intoxication also may cause the following: Snowy vision Photophobia Photopsia Decreased visual acuity Yellow halos around lights (xanthopsia) Transient amblyopia or scotomata GI symptoms in acute or chronic toxicity include the following: Anorexia[emedicine.medscape.com]
Diplopia
  • Other symptoms include fatigue, drowsiness, general muscle weakness, and visual disturbances such as blurring of vision, yellow-green or white halos around visual images, light flashes, photophobia, and diplopia.[medical-dictionary.thefreedictionary.com]
  • […] intracellular K Chronotropic Slows conduction in AV node (but increased spontaneous firing by Purkinje tissues) Toxic effect mainly ATPase pump effects History Fatigue Palpitations, DOE rare Pre-syncope or light headed Confusion Changes in colour vision Diplopia[emed.ie]
  • […] manifestations of confusion and weakness Chronic toxicity: Less GI symptoms, more prominent neurologic manifestations (lethargy, fatigue, delirium, confusion, disorientation) Visual changes are varied and may include chromatopsia (alterations in color vision), diplopia[ucsfmed.wordpress.com]
Scotoma
  • Less GI symptoms, more prominent neurologic manifestations (lethargy, fatigue, delirium, confusion, disorientation) Visual changes are varied and may include chromatopsia (alterations in color vision), diplopia, photophobia, decreased visual acuity, scotomas[ucsfmed.wordpress.com]
Confusion
  • The normal features of digitalis toxicity include: delirium, confusion, dizziness, headache, abdominal pain, diarrhea, vomiting, nausea and anorexia. It is equally commonly associated with cardiac arrhythmias.[symptoma.com]
  • Symptoms of Digoxin Toxicity overdoses could include: Nausea Vomiting Dizziness Weakness Confusion Vision Changes Low Blood Pressure Cardiac Instability Bradycardia Sudden Death The primary Digitalis Toxicity treatment is Digoxin Immune Fab (Ovine), made[youhavealawyer.com]
  • Symptoms of Digitalis toxicity include: nausea, vomiting, diarrhea, loss of appetite, confusion, heart palpitations, irregular heartbeat, halos or rings of light around objects, and blind spots or blurred vision.[attorneystrialgroup.com]
  • Symptoms of digitalis include the following: Vomiting Diarrhea Irregular pulse Nausea Loss of appetite Palpitations Confusion Visual changes If you or someone you know is taking Digitek and experiences any of these symptoms, it is important to see a doctor[yourlegalguide.com]
  • Confusion, difficulty in breathing, appearance of bright spots, blurring of vision or experiences of blind spots are also some symptoms which may have been reported.[overdoseinfo.com]
Dizziness
  • The normal features of digitalis toxicity include: delirium, confusion, dizziness, headache, abdominal pain, diarrhea, vomiting, nausea and anorexia. It is equally commonly associated with cardiac arrhythmias.[symptoma.com]
  • Digoxin toxicity Cardiology Clinical findings of digoxin overdose Clinical Loss of appetite, N&V, defects in color vision–reds and greens, or seeing halos around lights, psychotic changes, weakness, fatigue, or dizziness; new onset of arrhythmias typical[medical-dictionary.thefreedictionary.com]
  • Symptoms of Digoxin Toxicity overdoses could include: Nausea Vomiting Dizziness Weakness Confusion Vision Changes Low Blood Pressure Cardiac Instability Bradycardia Sudden Death The primary Digitalis Toxicity treatment is Digoxin Immune Fab (Ovine), made[youhavealawyer.com]
  • Digitalis toxicity can cause a heart attack, stroke, kidney failure, nausea, vomiting, dizziness, low blood pressure and an unstable or slow heart rate. Digitalis toxicity can also lead to death.[attorneystrialgroup.com]
  • Clinical manifestations are nonspecific but usually include gastrointestinal events (nausea, vomiting, diarrhea, and abdominal pain) along with circulatory effects (hemodynamic instability, dizziness or lightheadedness, and syncope).[dialnet.unirioja.es]
Lethargy
  • Symptoms of digitalis toxicity that affect the central nervous system include: drowsiness, lethargy, fatigue, neuralgia, headache, dizziness, seizures, hallucinations, confusion or giddiness, paresthesias and neuropathic pain.[symptoma.com]
  • Acute ingestion: GI symptoms (anorexia, nausea, vomiting, abdominal pain), neurologic manifestations of confusion and weakness Chronic toxicity: Less GI symptoms, more prominent neurologic manifestations (lethargy, fatigue, delirium, confusion, disorientation[ucsfmed.wordpress.com]
  • (early sign of significant toxicity) CVS: enhanced automaticity (atrial tachycardias (e.g. flutter, AF) with AV block, VF, VT, ventricular ectopic beats), bradyarrhythmias (Conduction delays / blocks, slow or regularised AF), hypotension, shock CNS: lethargy[lifeinthefastlane.com]
  • CNS CNS symptoms include: 7 Drowsiness Lethargy Fatigue Headache Dizziness Confusion Ocular Visual aberration often is an early indication of digitalis toxicity. Yellow-green distortion is most common, but red, brown, blue and white also occur.[btgplc.com]
  • Neurologic manifestations, such as lethargy, fatigue, confusion, and weakness, are common. Hyperkalemia or hypokalemia can be observed.[clinicaladvisor.com]
Altered Mental Status
  • Management: Anti-Digoxin antibodies DigiFab (preferred over Digibind) Mechanism Binds free Digoxin and complexes are renally excreted Indications Digoxin Toxicity (dysrhythmia, Serum Potassium 5.5, Altered Mental Status ) Acute Digoxin ingestion 10 mg[fpnotebook.com]
  • The signs and symptoms of chronic digoxin exposure warranting antidotal therapy include digoxin-associated dysrhythmias such as ventricular tachycardia/fibrillation and progressive bradydysrhythmias, as well as altered mental status.[pharmacytimes.com]
  • mental status attributed to digoxin toxicity. serum digoxin level greater than 10 ng/mL in adults at steady state (ie, 6-8 h post acute ingestion or at baseline in the clinical setting of chronic toxicity). ingestion greater than 10 mg in adults (40[ozemedicine.com]
  • Life-threatening arrhythmia, hyperkalemia and altered mental status are mentioned, but the article in UpToDate recommends that digoxin antibodies be used in every poisoning, because there is no therapy with a comparable efficacy and safety.[derangedphysiology.com]
  • mental status attributed to digoxin toxicity Rapidly progressive signs and symptoms of toxicity Management of dysrhythmias In hemodynamically stable patients, bradyarrhythmias and supraventricular arrhythmias may be treated with supportive care Short-acting[emedicine.medscape.com]
Vertigo
  • With an acute ingestion, symptoms such as nausea, vertigo , and vomiting are prominent. On the other hand, nonspecific symptoms are predominant in chronic toxicity.[en.wikipedia.org]

Workup

In patients with possible digitalis toxicity studies generally carried out include: Renal function studies, serum digoxin level, electrolytes and electrocardiogram [7].

The serum digoxin level is often used as a guide to right medication dosing and also to monitor compliance and assess toxicity. The relationship between serum digoxin level and digoxin toxicity still remains complex [8].

Clinical toxicity arises from the interactions between digitalis, general electrolyte abnormalities and the general effect they have on the the sodium-potassium adenosine triphosphatase pump.

Sinus Arrest
  • The rhythms prior to pacemaker insertion in group 1 included sinus arrest with junctional bradyarrhythmias (n 9), atrial fibrillation with a slow ventricular rate (n 11), and high-degree atrioventricular block (n 4).[emcrit.org]
  • 9.7%) 4(4.5%) 4(15.3%) Electrocardiographic Changes Atrial Fibrillation 13 (12.6%) 8(9%) 7 (26.9%) Bradycardia (ᐸ50 beats/min) 5 (4.9%) 3(3.4) 2(7.6%) Junctional Tachycardia 0(0.0%) 1(1.3%) 0(0%) Sustained ventricular tachycardia 1(0.97%) 0(0%) 0(0%) Sinus[omicsonline.org]
  • Life threatening arrhythmias (ventricular tachycardia, ventricular fibrillation , high degree A-V block, bradyarrhythma, sinus arrest) or hyperkalemia requires administration of Digoxin Immune Fab.[rxlist.com]
Ventricular Bigeminy
  • Rhythms that especially suggest digitalis toxicity include paroxysmal atrial tachycardia with block, non-paroxysmal accelerated junctional tachycardia, bi-directional VT, new onset ventricular bigeminy, and regularized AF.[calsprogram.org]
  • Most common finding: PVCs Other arrhythmias: bradycardia, atrial tachyarrhythmias with AV block, ventricular bigeminy, junctional rhythm, various degrees of AV nodal blockade, VT, VF Bidirectional ventricular tachycardia is encountered in rare instances[ucsfmed.wordpress.com]
  • Other ECG changes that suggest digoxin toxicity include bigeminal and trigeminal rhythms, ventricular bigeminy, and bidirectional ventricular tachycardia. [5] Blood test [ edit ] The level of digoxin for treatment is typically 0.5-2 ng/mL. [8] Since this[en.wikipedia.org]
Nodal Tachycardia
  • The most common are conduction disturbances or supraventricular tachyarrhythmias, such as atrial tachycardia (with or without block) and junctional (nodal) tachycardia. Ventricular arrhythmias are less common.[rxlist.com]
Flattened T Wave
  • Electrocardiographic signs of digitalis toxicity include first-degree atrioventricular (A-V) block with depressed S-T segments, shortened Q-T intervals, and flattened T waves.[medical-dictionary.thefreedictionary.com]

Treatment

Treatment of digitalis toxicity inculdes discontinuing digoxin therapy, digoxin-specific Fab antibody fragments, cardiac pacing, antiarrhythmic drugs, magnesium and hemodialysis and should be administered depending on the patient’s symptoms.

Prognosis

In digitalis toxicity, prognosis worsens with increase in age and other conditions that are comorbid. So children have the best outcome, followed by adults and older individuals [9]. Mortality rate will increase if the patient has new instances of dysrhythmia, advanced AV block or other major ECG abnormality.

When the minimal effective dose of a glycoside is multiplied 5-10 times, it becomes lethal. Double the minimal effective dose leads to minor toxic manifestations. Morbidity is usually 5-10% in many cases but it can be over 50% in individuals with digoxin level higher than 6 ng/mL.

Etiology

This condition generally arises as a result of complex interaction between various electrolyte, renal abnormalities and digoxin. A patient with severe hypokalemia or renal insufficiency will show more serious cardiotoxicity with normal levels of digoxin than a patient without renal or electrolyte disturbances and high levels of digoxin [3].

Acute toxicity arises with acute overdose or accidental exposure to plants that contain cardiac glycosides. Some of the factors that precipitate chronic toxicity include drug interactions, electrolyte disturbances, dehydration and deteriorating renal function.

Depletion of potassium stores is one of the most common precipitating causes of digitalis intoxication. This is common in patients with heart failure as a result of secondary hyperaldosteronism and diuretic therapy [4].

Some other causes of digitalis toxicity include: hypercalcemia, renal insufficiency, hyperthyroidism, myocardial infarction or ischemia, hypothyroidism, advanced age, hypoxemia, alkalosis, myocardial disease and acidosis.

Epidemiology

In the United States, 0.4% of all hospital admissions are closely linked to digitalis toxicity. 10-18% of people in nursing homes and 1.1% of outpatients taking the digoxin medication develop this condition [2].

In 2011, the AAPCC (American Association of Poison Control Centers) reported 1,601 single exposures to drug cardiac glycosides and 1,336 single exposures to plant cardiac glycosides.

Generally, pediatric poisoning from any substance is more common in males but for digitalis toxicity, there is no difference in occurrence between males and females. Again, women may be more susceptible to adverse effects of the condition than men.

Sex distribution
Age distribution

Pathophysiology

In the vascular smooth muscle, digoxin and other cardiac glycosides cause direct vasoconstriction in the arterial and venous system. The 2 components that make up the inotropic effect of digitalis are as follows:

  • Direct inhibition of membrane-bound sodium- and potassium-activated adenosine triphosphatase. This leads to increase in intracellular concentration of calcium.
  • Associated increase in a slow inward calcium current during the action potential. This current is the result of movement of calcium into the cell, and it contributes to the plateau of the action potential.

Digitalis glycosides work by binding specifically to adenosine triphosphate thereby inhibiting its enzymatic activity. It proceeds to impair the active transport of potassium into the fibres. This brings about a gradual increase in intracellular sodium and a gradual decrease in intracellular potassium.

The major electrolytic complication in acute, massive digoxin poisoning is hyperkalemia. However, Hyperkalemia is seen in pediatric patients with acute toxicity.

Prevention

There are no guidelines for prevention of digitalis toxicity.

Summary

Digitalis toxicity is a poisoning that occurs when excess doses of digoxin are consumed either acutely or over an extended period of time. Digoxin is found in foxglove plants of the genus Digitalis, hence the name. Digoxin is a cardiac glycoside and it is commonly used in the treatment of reentrant supraventricular tachycardia, atrial fibrillation and chronic heart failure [1].

The normal features of digitalis toxicity include: delirium, confusion, dizziness, headache, abdominal pain, diarrhea, vomiting, nausea and anorexia. It is equally commonly associated with cardiac arrhythmias.

Patient Information

All patients taking digoxin must be fully aware of the symptoms of digitalis toxicity. Also, there is need to fully understand drug interactions while maintaining proper hydration. Parents with child patients need to understand the importance of home child proofing as well as other preventive measures [10].

References

Article

  1. Slaughter RJ, Beasley DM, Lambie BS, Wilkins GT, Schep LJ. Poisonous plants in New Zealand: a review of those that are most commonly enquired about to the National Poisons Centre. The New Zealand Medical Journal 2012 125 (1367): 87–118. 
  2. Ahmed A, Rich MW, Love TE, Lloyd-Jones DM, Aban IB, Colucci WS, Adams KF, Gheorghiade M. Digoxin and reduction in mortality and hospitalization in heart failure: A comprehensive post hoc analysis of the DIG trial. European Heart Journal 2005 27 (2): 178–186.
  3. Bronstein AC, Spyker DA, Cantilena LR Jr, Rumack BH, Dart RC. 2011 Annual report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 29th Annual Report. Clin Toxicol (Phila). Dec 2012;50(10):911-1164.
  4. Litovitz TL, Klein-Schwartz W, White S, Cobaugh DJ, Youniss J, Drab A, et al. 1999 annual report of the American Association of Poison Control Centers Toxic Exposure Surveillance System. Am J Emerg Med. Sep 2000;18(5):517-74.
  5. Bronstein AC, Spyker DA, Cantilena LR Jr, Green JL, Rumack BH, Giffin SL. 2008 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 26th Annual Report. Clin Toxicol (Phila). Dec 2009;47(10):911-1084.
  6. Eisner DA, Kashimura T, Venetucci LA, Trafford AW. From the ryanodine receptor to cardiac arrhythmias. Circ J. Sep 2009;73(9):1561-7.
  7. Eichhorn EJ, Gheorghiade M. Digoxin. Prog Cardiovasc Dis 2002; 44:251.
  8. Hussain Z, Swindle J, Hauptman PJ. Digoxin use and digoxin toxicity in the post-DIG trial era. J Card Fail 2006; 12:343.
  9. Brubacher JR, Lachmanen D, Ravikumar PR, Hoffman RS. Efficacy of digoxin specific Fab fragments (Digibind) in the treatment of toad venom poisoning. Toxicon 1999; 37:931.
  10. Bronstein AC, Spyker DA, Cantilena LR Jr, et al. 2007 Annual Report of the American Association of Poison Control Centers' National Poison Data System (NPDS): 25th Annual Report. Clin Toxicol (Phila) 2008; 46:927.

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Last updated: 2018-06-22 05:32