Morgagni-Adams-Stokes syndrome.

Morgagni-Adams-Stokes syndrome (MAC) is a syncopal condition developing against the background of asystole, with subsequent development of acute cerebral ischemia. Most often, it develops in children with atrioventricular block grades II-III and sick sinus syndrome with a ventricular rate of less than 70-60 per minute in young children and 45-50 in older children.

Bradycardia and bradyarrhythmia lead to low cardiac output syndrome if the heart rate is less than 70% of the age norm. Normally, the lower limit of heart rate per minute in awake children over 5 years old is 60, under 5 years - 80; for children in the first year of life - 100, the first week of life - 95. During sleep, these limits are lower: less than 50 per minute in children over 5 years old and less than 60 for young children.

In children, the most common and dangerous, but relatively favorable to treatment, conduction disorders are sinus bradycardias, caused by increased tone of the vagus nerve against the background of hypoxia.

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Symptoms of Morgagni-Adams-Stokes syndrome

The child suddenly turns pale, loses consciousness, breathing becomes rare and convulsive, followed by cessation and increasing cyanosis. Pulse and blood pressure are not determined, heart rate is 30-40 per minute. Convulsions, involuntary urination and defecation may develop.

The duration of an attack can range from a few seconds to several minutes. Most often, the attack passes on its own or after appropriate treatment, but a fatal outcome is possible.

Treatment of Morgagni-Adams-Stokes syndrome

Treatment of hypoxemia in combination with single or double administration of age-related doses of atropine intravenously or into the muscles of the floor of the mouth, as a rule, quickly leads to restoration of the heart rate. More active treatment is required for bradycardias that have arisen against the background of various poisonings (poisons of some fly agarics, organophosphorus substances, beta-blockers, opiates, barbiturates, calcium channel blockers). In these cases, the dose of atropine is increased by 5-10 times and isoprenaline infusion is performed.

Emergency care for recurrent asystolic MAC attacks begins with a precordial blow (not recommended for young children), followed by intravenous administration of 0.1% atropine at a rate of 10-15 mcg/kg or 0.5% isoprenaline solution by jet stream at a dose of 0.1-1 mcg/kg x min) to 3-4 mcg/kg x min), and in older children - 2-10 mcg/kg x min). Atropine can be re-administered every 3-5 minutes (depending on the effect) until a total dose of 40 mcg/kg (0.04 mg/kg) is reached. If drug therapy is insufficiently effective, transesophageal, external percutaneous or intravenous cardiac electrical stimulation is performed under electrocardiographic control.

In pediatric practice, 0.1% epinephrine solution at a dose of 10 mcg/kg is rarely used, since in severe conduction disorders there is a risk of developing ventricular fibrillation. Epinephrine is administered intravenously by jet stream during the initial therapy of ventricular fibrillation or pulseless ventricular tachycardia, after which defibrillation is performed with a charge energy of 360 J. Epinephrine administration can be repeated every 3-5 minutes. The drug is also used in the presence of pulseless electrical activity of the heart and asystole. In symptomatic bradycardia that is not sensitive to atropine and transcutaneous electrical cardiac pacing, epinephrine is administered intravenously by drip at a rate of 0.05-1 mcg/kg x min).

The most appropriate method for preventing cardiac arrest in severe hyperkalemia is to slowly administer 10% calcium chloride solution intravenously at a dose of 15-20 mg/kg. If ineffective, it is administered again after 5 minutes. Sodium bicarbonate should not be administered after administration of the drug, as it increases the content of non-ionized calcium. The effective action of calcium chloride lasts for 20-30 minutes, so it is necessary to infuse 20% dextrose solution (4 ml/kg) with insulin (1 U per 5-10 g of dextrose) to increase the rate of potassium entry into cells.

It is important to take into account that calcium preparations in children enhance the toxic effect of cardiac glycosides on the myocardium, and therefore it is necessary to exercise great caution when prescribing them. In case of intoxication with cardiac glycosides, it is advisable to administer a 25% solution of magnesium sulfate at a dose of 0.2 ml / kg and a 5% solution of dimercaprol at a rate of 5 mg / kg. To increase the excretion of potassium, it is necessary to administer furosemide at a dose of 1-3 mg / kg x day). Cation-exchange resins are also used to remove potassium (sodium polystyrene sulfonate, caexylate are prescribed at 0.5 g / kg in 30-50 ml of 20% sorbitol solution orally or 1 g / kg in 100-200 ml of 20% dextrose solution into the rectum. The most effective means of reducing the level of potassium in the serum is hemodialysis.