Cardiac glycosides poisoning is an acute drug intoxication provoked by at least twice the dose of the drug. The main clinical manifestations include bradycardia, extrasystole, decreased myocardial contractility, nausea, weakness, change in color perception, abdominal and cardiac pain, diarrhea. It is diagnosed according to the data obtained during the collection of anamnesis, information provided by relatives of the victim, the results of laboratory and hardware examination. The main directions of therapy: removal of poison from the stomach, antidotes, correction of water-electrolyte disorders, symptomatic treatment.
T46.0 Cardiac glycosides poisoning and drugs of similar action
Cardiac glycosides poisoning (digitalis intoxication) develops with a relatively small excess of permissible dosages, and sometimes when using the drug in accordance with clinical recommendations. Symptoms of digoxin poisoning occur after taking 1.2-2 mg per day, corglikon — after simultaneous administration of 0.8-1 mg. These drugs have a small therapeutic range. Adults are more sensitive to overdose. Risk groups include elderly people, patients with renal insufficiency, receiving cardiac glycosides for coronary pathology, patients with mental illnesses living at home.
The main reason is taking the drug without taking into account factors that require a reduction in dosage. The drug accumulates in plasma and tissues, which leads to the development of a toxic effect. The phenomenon occurs in patients with creatinine clearance less than 50-80 ml / minute, chronic heart failure. The risk of overdose is increased in school-age patients (it is difficult to choose the dose and therapy regimen). Other situations that provoke poisoning:
- Suicide. Suicide attempts with cardiotonic medications are relatively rare. They account for about 8% of the total number of cases of suicidal attempts using medications. The mortality rate is 13%. The risk group consists of patients who are at the stage of recovery from depression, patients with psychiatric diseases, cancer patients.
- Random reception. Cardiac glycosides may be taken unintentionally instead of another medication. This happens if the tablets are not stored in their original packaging. There may be situations when an elderly person forgets that he has already drunk the prescribed drug and uses it again. With the availability of medicines, young children may eat pills out of curiosity.
- Non-drug poisoning. Occur when ingested berries of the May lily of the valley, oleander, rhododendron. These plants contain alkaloids that can affect the cardiovascular system. Exotoxicosis is mainly affected by young and middle-aged children who tend to taste berries growing in the wild.
- Non-traditional treatment. Some preparations of Chinese medicine to enhance potency contain bufadienolide, a cardioactive steroid derived from the glands of the Colorado toad bufo. Taking a large dose of the drug provokes the development of digitalis intoxication. Several similar cases were reported by the American Academy of Clinical Toxicology in 1993 and 1995.
CG inhibits the activity of the membrane Na+/K+-ATPase by 60%, thereby disrupting the process of polarization and repolarization of the myocardium. Some of the missing potassium ions are replaced by hydrogen ions, which contributes to the development of intracellular acidosis and extracellular alkalosis. The contractility of the heart decreases, hyposystole occurs. The ATP of the conducting system is more than twice as sensitive to the influence of cardiac glycosides compared to a similar enzyme in the myocardium. Therefore, against the background of a digitalis lesion, blockages of intracardiac impulse transmission are expressed.
In addition to the direct cardiotoxic effect, the drug acts on the central nervous system. Under its influence, the function of neurotransmitters is disrupted. Visual and mental disorders occur. The lesion of the peripheral nervous system is characterized by an increase in the excitability of the vagus nerve, which causes a sharp bradycardia. Hyperkalemia develops due to the deterioration of the return of potassium ions to skeletal muscle cells. It additionally provokes a weakening of the heart rate and hemodynamics.
The division is made taking into account the type of drug used (short, medium, long-acting), the mechanism of cardiac glycosides poisoning (suicidal, accidental, iatrogenic), the presence of complications (complicated, uncomplicated), a set of medications consumed (monointoxication with cardiac glycosides, combined poisoning with a complex of drugs), phase (toxicogenic, somatogenic). In clinical practice, a classification variant based on the severity of exotoxicosis is more often used:
- Easy. Occurs if the dosage of the drug has been exceeded 2-2.5 times. The symptoms are moderately pronounced, there is an AV blockade of the I degree, which does not pose a threat to the life of the victim. There are no significant neurological disorders. It occurs in patients who mistakenly took an increased dose of medication.
- Medium. The condition is deteriorating significantly. There are signs of damage to the central and peripheral nervous structures. Conduction blockade reaches grade II (more often Mobitz I). There is a violation of hemodynamics. Pathology occurs in people receiving digoxin on the background of kidney failure, children who accidentally drank pills.
- Heavy. All symptoms are expressed as much as possible. Intracardiac blockade can be subtotal or total. Dissociation in the work of the ventricles and atria is noted. The general condition is significantly disturbed. Death often occurs within the first 6-24 hours after taking the toxicant. It is observed mainly in suicide attempts.
The severity of cardiac glycosides poisoning directly depends on the dose taken by the victim. Mild intoxication is characterized by nausea, diplopia, a change in color perception according to the type of Van Gogh paints. There are complaints of loose stools, an unpleasant feeling in the heart area, weakness. On examination, the abdomen is soft, slightly painful in the projection area of the small intestine. The blood pressure is preserved, the pulse of normal tension and filling, the skin is moderately moist, of normal color. The total peripheral vascular resistance is increased.
With moderate exotoxicosis, neurological and mental disorders come to the fore. There is a headache, disorientation in space and time, hallucinations. All mild symptoms are present. Pronounced hyperhidrosis, pallor of the skin is determined. The pulse becomes more rare, but does not reach critical values. Blood pressure decreases moderately. The patient complains of the fear of death, a feeling of interruptions in the work of the heart.
Severe intoxication is accompanied by a picture of cardiac disorders. The clinical signs characteristic of less pronounced poisoning are repeatedly amplified. Bradycardia is diagnosed, a sharp decrease in blood pressure, symptoms of impaired cerebral blood flow (dizziness, depression of consciousness, coma). The patient is covered with a sticky cold sweat, peripheral veins subside, acrocyanosis is detected. When the respiratory center of the medulla oblongata is affected, respiratory insufficiency occurs.
A common complication – total AV block occurs in 25-30% of cases of severe digitalis lesion. At the same time, the work of the upper and lower parts of the heart becomes uncoordinated, which makes it impossible to maintain acceptable hemodynamic parameters. The ventricles contract with a frequency of 20-45 beats / minute due to the activation of ectopic foci. There is a high risk of fibrillation and asystole. Total-type AV blockade requires the patient to stay in cardiological intensive care and the installation of a pacemaker.
3-5% of the victims develop arrhythmogenic shock, which is manifested by the centralization of blood circulation, coma, pathological type of breathing. 5-7% of patients have seizures of Morgan-Adams-Stokes. With a prolonged and significant decrease in blood perfusion in the brain at the somatogenic stage, signs of cortical damage may be detected, accompanied by impaired thinking abilities, behavior and memory, headaches. It is detected in 1-2% of cases.
The diagnosis is made by the doctor of the ambulance team, confirmed in the hospital where the patient will be taken. Differentiation is carried out with FOS poisoning, other antiarrhythmic drugs, heroin. The consultation of a cardiologist, therapist, gastroenterologist, neurologist is required. The immediate management of the victim is usually handled by a resuscitator. The examination is carried out using the following methods:
- Physical. Blood pressure is maintained or reduced. In severe processes, this indicator can reach 70/40 mm Hg and lower. The pulse is less than 60-70 beats / min, sometimes tachycardia is detected. There are clinical signs of digitalis intoxication. During auscultation of the heart, interruptions and deafness of tones are detected.
- Laboratory. The plasma concentration of the toxicant is 3-10 ng/ml. The potassium content is higher than 5.3 mmol/l. There are acidosis phenomena, pH is below 7.3. There may be an increase in creatinine and urea, an increase in the activity of microsomal liver enzymes. In case of respiratory disorders, there is an increase in the partial pressure of carbon dioxide, a decrease in blood oxygenation.
- Hardware. The main method of hardware diagnostics is electrocardiography. In patients with a healthy heart, depression of the ST segment in the form of a bucket occurs under the influence of CG. In the presence of previous myocardial lesions, its sharp arcuate rise is noted. Other pathological phenomena may be present: QRS prolapse, two-phase P wave, extrasystoles.
Acute poisoning always requires hospitalization of the victim. This is due to the high risk of fatal complications. Patients with severe intoxication and pronounced clinical manifestations need resuscitation aid. Mild exotoxicoses can be stopped in the conditions of a therapeutic or toxicological department of a general profile. Therapy is aimed at removing the non-absorbed and absorbed poison, enhancing natural excretion, binding the toxicant with antidotes, correction of electrolyte disorders.
Regardless of the time that has elapsed since taking the toxic substance, a probe gastric lavage is performed. To do this, clean water is used, the volume of which can reach 10-15 liters per 1 procedure. After complete purification, a suspension of crushed activated carbon is injected, which helps to bind both the non-absorbed part of the drug and the toxicant circulating in the enterohepatic cycle. The sorbent dose is calculated according to the formula 1 g / kg of weight. In the presence of severe arrhythmia, manipulation is not performed.
At the prehospital stage, the patient may be prescribed diphenine, which has an antiarrhythmic effect without slowing down atrioventricular conduction. Bradycardia is stopped with the help of atropine. Infusion and symptomatic therapy is required. If necessary, the patient is transferred to a ventilator, the infusion of pressor amines begins. The dose of the latter is selected empirically by slow titration under the control of blood pressure. Atrial fibrillation is an indication for the start of cardiopulmonary resuscitation.
As an antidote, the patient receives unithiol 5% 1 ml per 10 kg of weight. The first 3 days require three intramuscular injections daily, then 1-2 injections. The general course is 7-10 days. Sodium citrate or trilon B is used . To eliminate hyperkalemia, glucose infusion with insulin and magnesium sulfate is necessary. The mixture promotes the entry of K+ into the cells. Sodium bicarbonate has a similar effect. Saline laxatives, loop diuretics are used. The latter should be used with caution. In addition to potassium, they remove magnesium from the body, contribute to the development of hypotension.
With a pronounced decrease in heart rate, atropine is administered to the patient, against the background of extrasystole, intravenous infusion of lidocaine is advisable. Diphenin is shown to displace CG from tissues. There is an unconfirmed opinion of a number of scientists that this drug improves the results of extracorporeal cleansing. An effective method is the infusion of fragments of antibodies to CG, which allows you to quickly restore the heart rate, eliminate the phenomena of intoxication. The dose of the drug is selected according to the amount of the toxic substance taken.
The patient is connected to an anesthesiological monitor for constant monitoring of the coronary rhythm. Forced diuresis and hemodialysis as a means of active excretion of a toxicant are considered ineffective, but can be used as part of a restorative complex. Pharmacological therapy does not differ from the one described above. The work of the heart with significant conduction blockages is provided with the help of an external or endocardial stimulator. It may require a ventilator, the installation of a central venous catheter, electric pulse action.
Prognosis and prevention
Cardiac glycosides poisoning has a positive prognosis for moderate and minor intoxication. Adverse prognostic factors include hyperkalemia resistant to the introduction of glucose-insulin mixture, II-III degree conduction blockade, chronic heart failure. The greatest number of deaths occurs in the first 24 hours after the onset of symptoms of exotoxicosis. The total mortality, according to various sources, is 2-10%. 85% of the dead were people who attempted suicide.
Prevention of drug poisoning consists in careful control of medications. Medicines should be stored where children, the elderly and patients with mental disabilities do not have access. Elderly patients receiving treatment with cardiac glycosides are required to have a pillbox, which prevents repeated administration of the drug. People suffering from depression and having suicidal tendencies need constant monitoring of relatives.