Reasons for the development of sick sinus syndrome

While the syndrome of weakness of the sinus node in adults predominantly has ischemic genesis and manifests with atrial fibrillation, in most cases in children it develops in the absence of an organic pathology of the cardiovascular system. Disorders of the pacemaker in childhood are often due to vegetative imbalance with predominance of parasympathetic influences and age involution of the sinus node, as a consequence of inflammatory myocardial lesions, metabolic pathologies, autoimmune lesions by specific antibodies to the conduction system of the heart. For etiologic factors, the following types of sinus sinus weakness syndrome are distinguished.

• Syndrome of weakness of the sinus node of an organic nature (with collagenosis, cardiomyopathies, amyloidosis, coronary heart disease, heart tumors, surgical traumas of the sinus node area, hormone-exchange cardiotoxic disorders and other pathological conditions).
• Regulatory (vagus) dysfunctions of the sinus node (vegetative-vascular dystonia with predominance of parasympathetic effects on the heart, hypervagonia with increased intracranial pressure, edema of the brain, vasovagal reflexes in organ pathology).
• Syndrome of weakness of the sinus node as a consequence of toxic effects (antiarrhythmic drugs, cardiac glycosides, tricyclic antidepressants, hypnotics, carbophos poisoning and other compounds blocking cholinesterase).
• Violation of the functions of the sinus node in children after surgical operations on the heart.
• Congenital impairment of sinus node functions.
• Autoimmune disorders of sinus node functions.
• Idiopathic disorders (cause not established).

In the first four cases, there is a so-called secondary syndrome of weakness of the sinus node, its elimination is directly dependent on the effectiveness of therapy of the underlying disease. The development of the syndrome in children who underwent surgery for the heart, most often has a progressive nature and requires interventional treatment (implantation of the pacemaker).

In pediatric cardiac practice, it is not often possible to detect any disease that can again lead to a disruption of the function of the sinus node. In these cases, it is customary to talk about the primary or idiopathic variant.

It is often extremely difficult to draw a line between an organic and functional change without having a morphological confirmation. This syndrome is fully described. The criterion of differential diagnosis, in addition to the degree of severity of the lesion, the evaluation of which is often quite arbitrary, is considered to be a reversible and irreversible nature of the changes. For a long time, apart from the term "syndrome of weakness of the sinus node", the concept of "sinus node dysfunction" was widely used, implying irreversibility in the first case and reversibility of the pathological process in the second. It can be assumed that the so-called idiopathic syndrome of weakness of the sinus node in children is a slowly current degenerative lesion of the conduction system of the heart, in which the earliest and most pronounced changes occur, apparently, in the innervation of the sinus node. Hereditary predisposition can concern both the formation of vegetative pathology, and the primary electrophysiological changes in the conduction system of the heart.

[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12]