Supraventricular tachyarrhythmias in children

Supraventricular (supraventricular) tachyarrhythmias include tachyarrhythmias with localization of the electrophysiological mechanism above the bifurcation of the bundle of the Hyis - in the atria, AV-connection, and arrhythmias with circulation of the excitation wave between the atria and ventricles. In the broadest sense, supraventricular tachyarrhythmias include sinus tachycardia due to acceleration of normal automatism of the sinus node, supraventricular extrasystole and supraventricular tachycardia proper (CBT). SVT represents the largest part of clinically significant supraventricular tachyarrhythmias in childhood.

Sinus tachycardia is diagnosed when recording sinus rhythm of high frequency (heart rate at 95th percentile and above) on all ECG quiescence. If sinus tachycardia is recorded for 3 months or more, it is regarded as chronic. Sinus tachycardia occurs with increased psychoemotional excitement, accompanies hyperthermic reactions, hypovolemia, anemia, thyrotoxicosis, occurs due to the use of a number of medications. Chronic sinus tachycardia can be a manifestation of persistent impairment of neurohumoral regulation of the heart rhythm. The frequency of chronic sinus tachycardia in childhood is unknown.

The term supraventricular heterotopic tachycardia refers to the atrial rhythm of high frequency (a minimum of three consecutive heartbeats) that results from abnormal myocardial stimulation. The source of the rhythm is localized above the bifurcation of the bundle of His. Supraventricular tachyarrhythmias originating from the atria or including atrial tissues as part of the arrhythmogenic substrate are most common in childhood. They are rarely accompanied by the development of life-threatening conditions (with the exception of prolonged attacks of paroxysmal tachycardia), but are often clinically significant. Children complain of a feeling of palpitations, a disturbance of well-being. With prolonged existence, this condition leads to heart remodeling with the expansion of its cavities, the development of arrhythmogenic myocardial dysfunction and arrhythmogenic cardiomyopathy. Supraventricular tachycardia in the children's population is met with a frequency of 0.1-0.4%. The most common electrophysiological mechanisms of supraventricular tachycardia in children are AV-reciprocal tachycardia (ventricular pre-excitation syndrome), AV-node reciprocal tachycardia (20-25% of all supraventricular tachycardias), atrial (10-15% among all supraventricular tachycardias) and AV-node ectopic tachycardia. Atrial fibrillation is rarely seen in childhood.

From 30 to 50% of supraventricular tachycardias detected in the neonatal period can spontaneously disappear by the age of 18 months as a result of maturation of the structures of the conduction system of the heart. When arrhythmias occur at a later age, spontaneous recovery occurs extremely rarely.

In 95% of cases, supraventricular tachycardias are found in children with a structurally normal heart. Among the extracardiac factors provoking the development of supraventricular tachycardia in children are vegetative disorders with a predominance of parasympathetic reactions, connective tissue dysplasia, hereditary predisposition (a burdened family history of cardiac arrhythmias and conduction), psychoemotional instability, central nervous system diseases, endocrine pathology, metabolic diseases, acute and chronic infectious diseases, and excessive NCA exercise (especially those associated with increased parasympathetic effects on the heart - swimming, diving, martial arts). Age-related risk periods for clinically significant supraventricular tachycardias in children - the period of the newborn and the first year of life, 5-6 years, the pubertal period.

Pathogenesis

Intracardial mechanisms for the development of supraventricular tachyarrhythmias include the anatomical and electrophysiological conditions for the onset of abnormal electrophysiological mechanisms of cardiac excitation: the presence of additional pathways for the impulse, foci of abnormal automatism, and trigger zones. The basis of sinus tachycardia is the increased automatism of the pacemaker's pacemakers themselves. The occurrence of abnormal electrophysiological processes in the myocardium can be caused by anatomical causes (congenital heart anomalies, postoperative scars). For the formation of the electrophysiological substrate of heterotopic arrhythmia in childhood, the preservation of embryonic rudiments of the conducting system is of importance; the role of mediators of the autonomic nervous system has been shown experimentally.

The pathogenesis of supraventricular tachyarrhythmias

Classification of supraventricular tachyarrhythmias

Classify supraventricular tachyarrhythmias, taking into account the localization and features of the electrophysiological mechanism and clinical-electrocardiographic manifestations.

• Supraventricular extrasystole is divided into a typical extrasystole and parasystole.
• Extrasystolia is divided into the atrial (left and right) and nodal.
• Isolate monomorphic (one morphology of the ventricular complex) and polymorphic (polytopic) extrasystole.
• In terms of severity, single, pair (two consecutive extrasystoles), interpolated, or intercalary (extrasystoles occur in the middle between two sinus contractions in the absence of compensatory pause), allorrhythmia (extrasystole occurs after a certain number of sinus complexes) -bigimia (every second contraction is an extrasystole ) and trembling (every third contraction is extrasystoles), etc.

Classification of supraventricular tachyarrhythmias

Symptoms of supraventricular tachyarrhythmias

Clinical manifestation of chronic sinus tachycardia can be a feeling of palpitation, which increases with exercise. This arrhythmia is typical for school-age children, it is often met during puberty. Despite the constantly increasing heart rate (100-140 per minute), children experience palpitations with emotional and physical exertion. Other symptoms include sleep disturbances, sleep and sleep, neurotic reactions, tics, stammering, increased sweating of the palms and feet. Girls suffer this type of rhythm disturbance 3 times more often than boys. In ECG, craniocaudal (sinus) morphology of the R wave is recorded . Chronic sinus tachycardia should be differentiated from heterotopic tachycardia from the upper part of the right atrium, in which, as a rule, there are no complaints of palpitation and the rigidity of the rhythm.

Symptoms and Diagnosis of Supraventricular Tachyarrhythmias

Treatment of supraventricular tachyarrhythmias

Emergency treatment of paroxysmal supraventricular tachycardia is aimed at interrupting the paroxysm of tachycardia and normalizing hemodynamics.

Stopping the attack begins with vagal tests: upside down, stand on hands, Aschner's test, Valsalva test, carotid sinus massage, pressing the root of the tongue. In young children, the most effective is upside down for a few minutes.

The tactics of emergency medication depend on the electrophysiological substrate of paroxysmal supraventricular tachycardia. Emergency therapy of paroxysmal supraventricular tachycardia with a narrow QRS complex and also with a wide QRS as a result of functional blockade of the bundle of the bundle are started with intravenous adenosine phosphate (1% solution in / in strumno: up to 6 months - 0.5 ml, from 6 months to 1 year - 0.8 ml, from 1 to 7 years - 1 ml, 8-10 years - 1.5 ml, over 10 years - 2 ml). If the ineffectiveness of the introduction can be repeated twice more with an interval of at least 2 minutes. Adenosine phosphate slows down through the AV node, interrupts the re-entry mechanism and helps restore sinus rhythm. The drug can cause cardiac arrest, so it should be administered under conditions that allow resuscitation if necessary.

Treatment of supraventricular tachyarrhythmias

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