Symptoms and diagnosis of sick sinus syndrome

In half of the patients, the syndrome of weakness of the sinus node proceeds asymptomatically, and manifestations characteristic of the sinus node weakness are randomly detected. The reason for going to the doctor in other patients are complaints about syncopal conditions, dizziness, fits of weakness, a sense of interruption and pain in the heart, headaches. In cases where it was possible to obtain previously registered ECG, it was found that 4-5 years before the treatment in the clinic, children already had at least sinus bradycardia or migration of the pacemaker. Thus, in the absence of treatment, i.e. In the course of the natural course of the disease, sinus node dysfunctions progressively progress from sinus bradycardia and pacemaker migration to the appearance of a sinoatrial blockade in 40% of cases, as well as replacement rhythms against a complete failure of the sinus node. All this allows us to doubt the innocuous nature of the initial electrophysiological phenomena. In most patients in childhood, despite the asymptomatic course, the sinus node weakness syndrome progresses. The conjugation of the degree of damage to the sinus node and the AV node was established. Such a generalized inclusion of different levels of the conducting system in the pathological process is due to the generality of embryonic development, the genetic program of morphogenesis, and the development of autonomic innervation of the conducting structures. ECG manifestations of the syndrome include a wide range of disorders: bradycardia, rhythm migration, sinus node stops and rhythm pause, sinoatrial block, slipping rhythms, supraventricular tachycardias, ventricular and supraventricular extrasystoles, abnormalities of AV conduction of various degrees.

I variant of the syndrome (dysfunction of the sinus node) is characterized by the least pronounced deviations from the norm from the rhythm and AV-conduction. Up to 30% of children complain of syncopal or pre-syncopal conditions (vasovagal mechanism of syncope).

With natural course at the next stage, it is possible to form both II and III variants of the syndrome of weakness of the sinus node. It depends on the specific electrophysiological situation of each child. In the presence of latent additional pathways and other conditions for the formation of an abnormal electrophysiological mechanism for the excitation of the myocardium, the third variant develops - tachycardia-bradycardia syndrome. Both variants (II and III) are characterized by similar parameters of the basal sinus rhythm, including mean daytime and mean night values of the heart rate, the duration of the rhythm pauses, the reactivity of the sinus rhythm under the conditions of medicinal and stress tests. With each of these variants compensatory substitution rhythms appear. Only in some cases they are represented by single contractions or slow rhythms from the underlying parts of the conduction system of the heart (variant II), while in others they are usually re-entry and ectopic tachycardias (variant III).

For the IV version of the syndrome of weakness of the sinus node, the most pronounced disorders are characteristic. They manifest a persistent bradycardia of about 40 per minute or less, periods of asystole more than 2 seconds. In some cases, the pause of the rhythm can reach 7-8 seconds or more. In some children (IV variant) the sinus rhythm does not register or single sinus complexes are detected. This option includes a constant bradycardic form of atrial fibrillation-flutter. In these cases, it is important to evaluate the ECG recorded on the sinus rhythm for the diagnosis of the syndrome. The diagnosis is valid for the detection of bradycardia, asystole or sinoatrial blockade. Virtually all children with the IV variant of the syndrome have signs of lesion of the underlying parts of the conduction system of the heart and electrical instability of the myocardium: prolongation of the QT interval, alternative to the T wave, depression of the ST segment. Ventricular extrasystole. This group of children has the most severe course of the syndrome of weakness of the sinus node. 44% of children notice dizziness, attacks of severe weakness with blackout, in 50% of cases they are accompanied by severe disorders of cerebral circulation - syncopal conditions. Unlike children with I variant of the syndrome, fits of consciousness loss in the IV variant are caused by sudden cessation or sharp slowing down of the heart - Morgany-Adams-Stokes attacks. They are accompanied by a sudden sudden pallor, sometimes with a stop in breathing, with convulsions. The duration of attacks ranges from several seconds to several minutes. If it is impossible to stop, they lead to a sudden cardiac death of the child. The prevalence of the lesion, which includes all levels of the conduction system of the heart and the working myocardium, under conditions of a gross violation of neurovegetative regulation of the heart rhythm, allows the IV variant to be classified as cardioneuropathies.

[1], [2], [3], [4], [5], [6], [7], [8]