Paroxysmal tachycardia in children

This type of heart rhythm disorder is understood as a sudden, sharp increase in heart rate, manifested in the form of specific changes on the ECG, lasting from several seconds to many hours (sometimes days) with a characteristic sudden end to the attack and normalization of the rhythm.

Paroxysmal tachycardia in children is a fairly common type of arrhythmia, occurring with a frequency of 1:25,000 of the child population. Among other types of heart rhythm disorders, paroxysmal tachycardia is detected in 10.2% of all arrhythmias.

Paroxysmal tachycardia is a heart rhythm disorder that manifests itself in sudden attacks of palpitations with specific electrocardiographic manifestations (heart rate over 150-160 beats per minute in older children and over 200 beats per minute in younger children), lasting from several minutes to several hours.

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Causes of paroxysmal tachycardia:

• disturbances of autonomic regulation of heart rhythm;
• organic heart disease;
• electrolyte disturbances;
• psycho-emotional and physical stress.

Paroxysmal tachycardia in most cases occurs in children without organic heart disease and is considered equivalent to a panic attack. In terms of age, attacks of paroxysmal tachycardia are observed in older children, adolescents, and infants. The maximum frequency of attacks is established at the age of 4-5 years.

The intracardiac mechanisms of initiation and implementation of an attack of paroxysmal tachycardia have been studied in sufficient detail. The electrophysiological basis of paroxysmal tachycardia is the occurrence of a circular wave (re-entry) from the sinoatrial, atrioventricular node or atrium, or a sharp increase in intrinsic automatism in the ectopic focus.

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Symptoms of paroxysmal tachycardia

In clinical terms, children with paroxysmal tachycardia attacks have both predisposing and provoking factors. Unfavorable pregnancy and childbirth are observed in almost all mothers. As a rule, families of children with paroxysmal tachycardia have a high percentage of people with autonomic dysfunction, psychosomatic diseases, and neuroses.

Features of the constitution, structure of the conduction system of the heart can serve as the basis for the development of paroxysmal tachycardia. The existence of accessory conduction pathways (ACP) contributes to the development of WPW syndrome, predisposing to attacks of paroxysmal tachycardia and aggravating them. In WPW syndrome, attacks of paroxysmal tachycardia occur in 22-56% of children, which confirms the importance of a thorough ECG examination of this category of patients. In general, the somatic status of children with attacks of paroxysmal tachycardia is characterized by the presence of foci of chronic infection (chronic tonsillitis, chronic diseases of the paranasal sinuses, etc.), dyshormonal disorder (delayed puberty, irregular menstruation in girls, etc.), dyskinetic manifestations from the gastrointestinal tract and biliary tract. The body weight of children with paroxysmal tachycardia is usually within the normal range, but children with low weight are often encountered, especially at the age of over 10-12 years.

In the neurological status, 86% of children have individual organic microsigns. In 60% of children, signs of hypertensive-hydrocephalic syndrome are detected. Children have pronounced vegetative lability of the vasomotor apparatus, manifested by persistent, red diffuse dermographism, acrohyperhidrosis of the hands, and increased vascular pattern of the skin. In the vegetative status, most have vagotonic initial tone and hypersympathetic-tonic reactivity. Vegetative support of activity is usually insufficient, manifested by a hyperdiastolic variant of the wedge-orthostatic test.

In general, we can talk about the insufficiency of the sympathetic division of the autonomic nervous system in patients with paroxysmal tachycardia, which is combined with increased parasympathetic tone.

Anxiety-depressive and phobic experiences are a characteristic component of the mental status of this group of patients. This is especially true for older children who have a fairly long history of unsuccessful treatment for attacks of paroxysmal tachycardia, especially if they occur frequently and require intravenous administration of antiarrhythmic drugs by an ambulance team to stop them. In addition to this type of mental trauma, the microsocial environment of a child with paroxysmal tachycardia is often unfavorable (single-parent families, chronic alcoholism of parents, conflicts in the family, etc. are common), which contributes to the formation of a pathocharacterological anxious radical of personality.

The most characteristic manifestations are observed during a paroxysm of paroxysmal tachycardia. An attack of paroxysmal tachycardia mainly occurs against the background of emotional stress, and only in 10% of cases is physical activity the provoking factor. Some children may have a premonition of an approaching attack. Most older children and adolescents can determine the moment of the onset and end of an attack with complete accuracy. An attack of paroxysmal tachycardia is accompanied by noticeable changes in hemodynamics: stroke output decreases, peripheral resistance increases, as a result of which regional blood supply to the brain, heart, and other internal organs worsens, accompanied by painful, distressing sensations. During an attack of paroxysmal tachycardia, attention is drawn to increased pulsation of the neck vessels, pallor, sweating of the skin, slight cyanosis of the lips, mucous membranes of the oral cavity, a possible increase in temperature to subfebrile numbers and chill-like hyperkinesis. After the attack, a large amount of light urine is excreted. The child's reaction to the attack is determined by his age and emotional and personal characteristics. Some children tolerate the attack of tachycardia quite calmly, and can continue doing their usual activities (playing, reading). Sometimes only attentive parents can detect the presence of short attacks of paroxysmal tachycardia by some subjective signs. If the attack is long (hours, days), then the children's health noticeably worsens. Patients attract attention to themselves with anxious behavior, restlessness, complain of severe tachycardia ("the heart jumps out of the chest"), a feeling of pulsation in the temples, dizziness, weakness, dark circles in the eyes, a feeling of lack of air, nausea, and the urge to vomit.

Some children have developed skills that allow them to stop an attack by holding their breath and straining (i.e. vagal reflexes), sometimes vomiting helps, after which the attack ends. In 45% of children, attacks occur in the evening and at night, in 1/3 - only during the day. Evening attacks of paroxysmal tachycardia are the most severe. The average duration of an attack is 30-40 minutes.

It is necessary to carry out differential diagnosis between chronic (non-paroxysmal) tachycardia and paroxysmal tachycardia if the paroxysm of tachycardia lasts for several days. The first attack of paroxysmal tachycardia is stopped on its own in 90% of cases, while repeated ones - only in 18%. Vagal tests (oculocardial reflex, Valsalva test, Thomas-Roux solar reflex - pressing with a clenched fist in the solar plexus area) are used to stop an attack of paroxysmal tachycardia. Children, who have a widened QRS complex on the ECG during the attack, tolerate paroxysmal tachycardia worse; in this variant, regional hemodynamic disorders are possible.

ECG changes of a secondary nature due to a decrease in stroke volume during paroxysmal tachycardia and deterioration of coronary blood flow may be observed even several days after the attack. EEG shows signs of insufficiency of the mesodiencephalic structures of the brain in 72% of cases, with a decrease in the threshold of seizure readiness upon provocation in 66%. No epileptic activity is observed.

Types of paroxysmal tachycardia

Most authors distinguish two main forms of paroxysmal tachycardia: supraventricular and ventricular.

• Paroxysmal supraventricular tachycardias. In children, in most cases, they are functional in nature and often occur as a result of changes in the autonomic regulation of cardiac activity.
• Ventricular paroxysmal tachycardias. They occur rarely. They are considered life-threatening conditions. As a rule, they occur against the background of organic heart diseases.

The following criteria are used to diagnose an attack of paroxysmal tachycardia:

1. heart rate more than 200 beats per 1 min in young children and more than 150 beats per 1 min in older children and adolescents, while the rhythm is stable;
2. unusual P wave different from the sinus wave;
3. a paroxysm is defined as the presence of at least 3 contractions in a row;
4. the ventricular QRS complex is preceded by a P wave;
5. PR interval is usually normal or prolonged;
6. secondary ST-T changes are noted;
7. the use of vagal tests (Dagnini-Aschner, solar reflex) leads to the cessation of the attack (with the ectopic variant of paroxysmal tachycardia, the effect is often absent).

Treatment of paroxysmal tachycardia

Paroxysmal supraventricular tachycardia

In the treatment of paroxysmal supraventricular tachycardia, vagal tests are performed, drugs that affect the central nervous system and antiarrhythmic drugs are prescribed.

• Vagal tests (reflex action on the vagus nerve).
• Carotid sinus massage. Each sinus is acted upon in turn for 10-15 seconds, starting with the left one as it has more vagus nerve endings.
• Valsalva's test - straining with maximum inhalation while holding the breath for 30-40 seconds.
• Mechanical irritation of the pharynx - provocation of the gag reflex. In younger children, these procedures are replaced by strong pressure on the abdomen, which often causes a straining reflex or a "diving" reflex. This complex reflex can also be induced by irritating the child's head and/or face with ice water. It is necessary to be prepared to treat severe bradycardia and even asystole, which can occur due to a sharp increase in vagal tone with such interruption of supraventricular arrhythmias.
• Drugs that affect the central nervous system.

The relief of an attack of paroxysmal supraventricular tachycardia should begin with the prescription of drugs that normalize cortical-subcortical relationships. You can prescribe phenibut (from 1/2 to 1 tablet), carbamazepine (10-15 mg/kg per day), valerian tincture (1-2 drops per year of life), peony tincture (1-2 drops per year of life), hawthorn tincture (1-2 drops per year of life), as well as potassium and magnesium preparations (potassium and magnesium aspartate).

• Antiarrhythmic drugs

If the above therapy is ineffective, antiarrhythmic drugs are prescribed after 30-60 minutes, which are used sequentially (if there is no effect on the previous one) at intervals of 10-20 minutes. At first, it is recommended to use a 1% solution of triphosadenine without dilution at an age dose of 0.5 mg/kg intravenously by jet stream quickly (in 2-3 seconds). If necessary, the drug can be administered again in a double dose after 5-10 minutes. If the QRS complex on the electrocardiogram is narrow, and the use of triphosadenine did not lead to the cessation of the attack, it is recommended to use a 0.25% solution of verapamil intravenously in a 0.9% solution of sodium chloride at a dose of 0.1-0.15 mg/kg. Contraindications for its use include atrioventricular block, arterial hypotension, Wolff-Parkinson-White syndrome, severe impairment of myocardial contractility, and beta-blocker therapy. If necessary, after verapamil, 0.1-0.3 ml of 0.025% digoxin solution is slowly administered intravenously for supraventricular tachycardia.

Termination of an attack of supraventricular tachycardia can be achieved with beta-blockers (propranolol is prescribed at a dose of 0.01-0.02 mg/kg with its increase to a maximum total of 0.1 mg/kg, esmolol - at a dose of 0.5 mg/kg and others intravenously). However, in children, drugs of this group are rarely used.

• Paroxysmal tachycardia with wide QRS complexes

Stopping an attack of tachycardia after using triphosadenine is first carried out with giluritmal, amiodarone or procainamide together with phenylephrine, and only if there is no effect is lidocaine used in the form of a 1% solution intravenously by slow jet stream in a 5% dextrose solution at a rate of 0.5-1 mg/kg.

• Treatment when electrocardiogram recording is not possible

Slow intravenous administration of a 2.5% giluritmal solution at a dose of 1 mg/kg is indicated. In addition, a 5% amiodarone solution is used intravenously slowly in a 5% dextrose solution at a dose of 5 mg/kg. If there is no effect, a 10% procainamide solution in 0.9% sodium chloride solution is administered intravenously slowly at a rate of 0.15-0.2 ml/kg with simultaneous intramuscular administration of a 1% phenylephrine solution at a dose of 0.1 ml per year of life.

• Electropulse therapy

If drug treatment is ineffective, the attack persists for 24 hours, or if signs of heart failure increase, electropulse therapy is performed.

The prognosis for paroxysmal tachycardia is good, unless, of course, organic heart disease is added. Treatment of paroxysmal tachycardia, in addition to the attack, when antiarrhythmic drugs are used (in case of failure of reflex action by vagal tests), is carried out in the interictal period. The use of finlepsin (in an age-appropriate dose) in combination with psychotropic (sedative) drugs, the appointment of acupuncture, vegetotropic drugs, psychotherapy are effective.