Sinus node weakness syndrome in children

Sick sinus syndrome (SSS) is one of the most polymorphic cardiac rhythm disorders in children, associated with the risk of developing syncope.

The basis of the syndrome is changes in the functional state of the main source of cardiac rhythm, which, due to various reasons, cannot, from a certain point on, fully perform the role of the leading pacemaker and exercise control over the pacemaker.

ICD-10 code

In ICD 10, sick sinus syndrome corresponds to code 149.5 in the category “Cardiac rhythm disorders”.

Epidemiology of sick sinus syndrome

The prevalence of sick sinus syndrome in childhood is quite high and, according to various authors, ranges from 1.5 to 5 per 1000, reaching 1% among patients with cardiac pathology. In surgical clinics, about 10% of all heart rhythm disorders are associated with sick sinus syndrome. Sick sinus syndrome accounts for up to 30% of all heart rhythm disorders in children. Up to 50% of patients requiring a pacemaker have some kind of dysfunction of the sinus node. When examining children considered healthy, signs of dysfunction of the sinus node are detected in 2% with a standard ECG, and in 2.7% with Holter monitoring. Sinus bradycardia (the most common manifestation of sinus node dysfunction) is found in 3.5% of healthy schoolchildren. According to the population ECG screening of children in Russia, including ECG data from 5441 children, the prevalence of rhythm migration is 1.9%, escape and replacement supraventricular rhythms - 0.7%, and sinoatrial block - 0.3%. During Holter monitoring of children aged 1 year, 19% have escape and replacement idioventricular rhythms, 7% have episodes of sinus node arrest, and 11% have sinoatrial blocks. Thus, certain phenomena that are part of the symptom complex of sick sinus syndrome are common in the population, and a fairly significant part of the population has electrophysiological features from an early age that probably predispose to the subsequent formation of sinus node dysfunctions when exposed to various unfavorable factors.

Causes of Sick Sinus Syndrome

While sick sinus syndrome in adults is predominantly of ischemic origin and manifests itself as atrial fibrillation, in most cases in children it develops in the absence of organic pathology of the cardiovascular system. Disturbances of the pacemaker in childhood are often caused by vegetative imbalance with a predominance of parasympathetic influences and age-related involution of the sinus node, as a consequence of inflammatory lesions of the myocardium, metabolic pathologies, autoimmune damage by specific antibodies to the cardiac conduction system. According to etiological factors, the following types of sick sinus syndrome are distinguished.

Causes of Sick Sinus Syndrome

Classification of sick sinus syndrome

Most often, the classifications of sick sinus syndrome suggested using the presence or absence of clinical manifestations, ECG patterns on a standard ECG or during Holter monitoring, and an increase in heart rate during exercise tests. Since the early 1990s, pediatric cardiology practice has been dividing this pathology into clinical and electrocardiographic variants of sick sinus syndrome in children depending on the nature, sequence of increase, and severity of changes in the cardiac conduction system, taking into account a stable combination of ECG manifestations, circadian rhythm changes according to Holter monitoring, heart rate response to exercise, and concomitant lesions of the cardiac conduction system.

Classification of sick sinus syndrome

Symptoms and Diagnosis of Sick Sinus Syndrome

In half of the patients, the disease is asymptomatic, and manifestations characteristic of the sick sinus syndrome are detected by chance. The reason for visiting a doctor in the remaining patients are complaints of syncope, dizziness, attacks of weakness, a feeling of interruptions and pain in the heart, headaches. In those cases where it was possible to obtain previously registered ECGs, it was found that 4-5 years before visiting the clinic, the children already had at least sinus bradycardia or pacemaker migration. Thus, in the absence of treatment, i.e. with the natural course of the disease, sinus node dysfunction gradually progresses from sinus bradycardia and pacemaker migration to the appearance of sinoatrial block in 40% of cases, as well as substitution rhythms against the background of complete failure of the sinus node.

Symptoms and Diagnosis of Sick Sinus Syndrome

Treatment of sick sinus syndrome

Emergency therapy for the development of dizziness, syncope, and severe asystole against the background of bradycardic rhythm disturbances includes the administration of vagolytic drugs (atropine) or drugs with pronounced beta-adrenergic activity (isoprenaline).

The tactics for bringing a child out of a syncopal state are indirect heart massage and artificial respiration. The administration of one of the following drugs is indicated:

• epinephrine at a dose of 0.05 mg/year intramuscularly or intravenously once;
• isoprenaline IM 0.5-1.0 ml (0.1-0.2 mg) IM or IV once;
• atropine 0.1% solution intravenously at a dose of 0.01-0.02 mg/kg, no more than 2.0 mg;
• phenylephrine 1% solution intramuscularly 0.1 ml/year of life (no more than 1.0 ml).

Treatment of sick sinus syndrome

Forecast

Unfavorable prognostic signs in children with sick sinus syndrome are considered to be attacks of loss of consciousness, progressive decrease in average daytime, maximum and minimum daytime and nighttime heart rate indicators according to Holter monitoring data, increase in the number and duration of rhythm pauses, occurrence of additional rhythm and conduction disturbances, inadequate increase in sinus rhythm heart rate during a test with dosed physical activity, aggravation or provocation of additional rhythm disturbances during tests. Familial cases of the disease are prognostically unfavorable. Sudden cardiac death in families in direct relatives at a young age (up to 40 years) is considered an unfavorable prognostic factor.