Heart rhythm disorders in children

Heart rhythm disturbances occupy one of the leading positions in the structure of morbidity and mortality of the child population. They can be presented as a primary pathology or develop against the background of an existing disease, usually a congenital heart defect. Cardiac arrhythmias often develop at the height of infectious diseases, complicate diseases of other organs and systems of the body - CNS lesions, systemic diseases of connective tissue, metabolic diseases, endocrine pathology. Heart rhythm disturbances often act as one of the symptom complexes of many hereditary diseases. The importance of arrhythmias is due to their prevalence, tendency to chronic course, high risk of sudden death. The intensive development of childhood arrhythmology was facilitated by the development and introduction into clinical practice of highly informative research methods: Holter monitoring, high-resolution electrocardiography, surface mapping, Doppler echocardiography and electrophysiological studies of the heart. In the absence of signs of organic defects, the basis of rhythm disturbances is considered to be so-called idiopathic changes in the electrophysiological properties of the cardiac conduction system; understanding their essence is the subject of numerous scientific studies.

Identification of the pathogenetic bases of arrhythmias required expansion of our knowledge in the field of cardiac electrophysiology, features of autonomic regulation of cardiac rhythm, state of extra- and intracardiac sensory receptors, role of circulating mediators of the autonomic nervous system, cellular metabolism, stress-limiting systems, molecular-genetic bases of electrogenesis, autoimmune mechanisms. Such a comprehensive understanding of the problem has led to significant progress in the field of treatment and prevention of cardiac arrhythmias and sudden cardiac death. The main electrophysiological mechanisms of rhythm disturbances in childhood are abnormal automatism, re-entry mechanism with participation of additional impulse conduction pathways or trigger mechanisms. Genetic mechanisms play a particularly important role in development of a number of life-threatening arrhythmias - long QT syndrome, polymorphic ventricular tachycardia, Brugada syndrome. Currently, a certain spectrum of mutations responsible for development of life-threatening arrhythmias has been established. Changes in neurovegetative regulation of the heart are also of great importance, especially in cases of rhythm disturbances in children without signs of organic heart disease. All of the above mechanisms are specific to each type of heart rhythm disturbance, they are not isolated from each other, but interact. Thus, for the occurrence and maintenance of the electrophysiological substrate of arrhythmia, the preservation of the embryonic rudiments of the conduction system, disturbance of the neurovegetative regulation of the rhythm are important, in some cases the main role can be played by anatomical conditions, for example, surgical interventions. The neurovegetative basis of arrhythmias is caused in childhood by disturbances or features of the maturation of the vegetative centers of rhythm regulation, a certain role can be played by hereditary predisposition.

Unlike adults, children often have asymptomatic arrhythmia and in 40% of cases it is an accidental finding, which makes it impossible to accurately determine the duration and age of the child at the onset of arrhythmia. In some cases, for example, with long QT syndrome, the doctor's and parents' ignorance of the disease leads to tragic consequences: the first and only syncopal attack in life can lead to sudden cardiac death. Chronic arrhythmia is often diagnosed too late, when no therapy can prevent a fatal outcome. Certain difficulties exist in the clinical diagnosis of arrhythmia in newborns and young children. During this period of childhood, arrhythmia is most often complicated by the development of heart failure.

There are many known variants of cardiac arrhythmias differentiated on the basis of the leading clinical and electrophysiological phenomenon, since several types of arrhythmias are often detected in the same child. In childhood, it is advisable to distinguish supraventricular and ventricular tachyarrhythmias, sick sinus syndrome, supraventricular and ventricular extrasystoles. High degrees of AV block are also accompanied by rhythm disturbances. All existing rhythm disturbances are conditionally divided into two groups - tachyarrhythmias and bradyarrhythmias. Tachyarrhythmias are the most polymorphic, and their differential diagnosis is quite difficult. In recent years, a separate group of primary electrical diseases of the heart has been distinguished, combining hereditary forms of life-threatening arrhythmias - long and short QT syndrome, Brugada syndrome, polymorphic ventricular tachycardia.

In most cases, with the exception of paroxysmal tachycardia (sudden onset and end of an attack) and long QT syndrome (repeated syncope), children present numerous but non-specific complaints. However, there are also patterns in the clinical polymorphism of various types of rhythm disturbances, which must be identified and taken into account when prescribing treatment and determining the prognosis.

The problem of differential diagnostics of syncopal conditions in childhood is relevant. They are often caused by cardiac arrhythmia, most often by ventricular tachycardia, sick sinus syndrome and high degrees of AV block. Among cardiogenic causes of attacks of loss of consciousness, one of the leading places is occupied by primary electrical diseases of the heart, of which the most common is the syndrome of the long QT interval (CYHQ-T). In the diagnostics of many types of arrhythmia, the role of family electrocardiographic examination should not be underestimated; its results often become an important argument in making a diagnosis. Currently, much attention is paid to molecular genetic studies.

The choice of treatment tactics depends on many factors, including the mechanism of development of cardiac arrhythmias, age of manifestation, frequency, severity of clinical symptoms, presence of structural changes in the heart. Treatment of children with arrhythmias includes emergency and chronic pharmacotherapy, interventional methods, including implantation of antiarrhythmic devices (pacemakers and defibrillators). Children with supraventricular (supraventricular) paroxysmal tachycardias, life-threatening ventricular tachyarrhythmias (ventricular tachycardia, ventricular fibrillation, CYMQ-T) and bradyarrhythmias (sick sinus syndrome, complete AV blocks) require emergency therapy. Chronic pharmacotherapy of cardiac arrhythmias in children includes correction of neurovegetative disorders of cardiac rhythm regulation, control of abnormal electrophysiological mechanism of myocardial excitation using antiarrhythmic drugs of classes I-IV, as well as symptomatic therapy, if indicated. In the last decade, the development of the catheter ablation method has supplanted the role of pharmacological methods of therapy. However, in young children who do not have organic heart disease, as well as in patients with cardiac arrhythmias against the background of severe disorders of the autonomic regulation of cardiac rhythm, drug treatment methods have an advantage. In the treatment of life-threatening cardiac arrhythmias, an important resource is implantable antiarrhythmic devices: pacemakers and cardioverter-defibrillators. However, when implanting a cardioverter-defibrillator in children with life-threatening arrhythmias, adequate selection of antiarrhythmic therapy is of great importance.

[ 1 ], [ 2 ], [ 3 ]