Although several variables were associated with the development of sick sinus syndrome (e.g, higher body mass index, hypertension, prior cardiovascular event), advancing age was the most significant risk factor for sick sinus syndrome (hazard ratio 1.73 for each additional 5 years of age) 6). Only a few epidemiologic studies have been published.Ī pooled analysis of 20,572 patients from 2 large epidemiology studies (the Atherosclerosis Risk in Communities and Cardiovascular Health Study trials) who were followed for an average of 17 years, 291 incident cases of sick sinus syndrome were noted, yielding an incidence rate of 0.8 cases per 1000 person-years 5). Symptomatic patients are generally older, in seventh or eighth decade of life, with frequent comorbidities. Due to its relationship with advanced age, sick sinus syndrome is more prevalent in countries where citizens have a longer life expectancy. It is estimated that the incidence of sick sinus syndrome in the United States is approximately 1 in 600 cardiac patients older than 65 years 4). The epidemiology of sick sinus syndrome is difficult to study, given its nature and varying manifestations, including nonspecific symptoms and electrocardiographic (ECG) findings. Supraventricular tachycardia (eg, atrial fibrillation, atrial flutter, and atrial tachycardia as part of the tachycardia-bradycardia syndrome) 3).Inadequate heart rate response to physiologic demands during activity (chronotropic incompetence).However, sinus node dysfunction and sick sinus syndrome are often used interchangeably.Ī conglomeration of electrocardiogram (ECG) abnormalities represent manifestation of sinus node dysfunction, including 2) : When sinus node dysfunction is associated with symptoms such as dizziness or syncope, sick sinus syndrome is a more clinically representative term. Sinus node dysfunction is characterized by dysfunction of the sinoatrial (SA) node that is often associated with senescence of the node and surrounding atrial myocardium 1). Parasympathetic input via the vagus nerves decreases the sinoatrial (SA) nodal pacemaker and is the dominant input at rest, wheras sympathetic nerve input, as well as the adrenal medullary release of catecholamines, increases the sinus rate during exercise and stress. The sinoatrial (SA) node is innervated by the parasympathetic and the sympathetic nervous systems the balance between these systems controls the pacemaker rate. Many people with sick sinus syndrome eventually need a pacemaker to keep the heart in a regular rhythm.
Cardiac surgery, especially to the atria, is a common cause of sick sinus syndrome in children. Sick sinus syndrome is more common in elderly adults, where the cause is often a non-specific, scar-like degeneration of the conduction system. Sick sinus syndrome is relatively uncommon, but the risk of developing sick sinus syndrome increases with age. In sick sinus syndrome, these signals are abnormally paced.Ī person with sick sinus syndrome may have heart rhythms that are too fast, too slow, punctuated by long pauses - or an alternating combination of all of these rhythm problems. Normally, the sinoatrial (SA) node produces a steady pace of regular electrical impulses. The sinus node is an area of specialized cells in the upper right chamber of the heart that controls the rhythm of your heart (see Figures 1). Although the term “sick sinus syndrome” was first used to describe the sluggish return of sinoatrial (SA) nodal activity following electrical cardioversion, it is now commonly used to describe the inability of the sinoatrial (SA) node to generate a heart rate commensurate with the physiologic needs of an individual.
Sick sinus syndrome is a group of abnormal heartbeats (arrhythmias) presumably caused by malfunction of the sinus node, the heart’s “natural” pacemaker. Sick sinus syndrome - also known as sinus node disease or sinus node dysfunction - is the name for a group of heart rhythm problems (arrhythmias) in which the sinus node - the heart’s natural pacemaker - doesn’t work properly.
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