• Clinical science

Sick sinus syndrome (Sinus node dysfunction)


Sick sinus syndrome (SSS) refers to the dysfunction of the sinoatrial node and is responsible for several types of arrhythmia. It comprises bradyarrhythmias (e.g., sinus bradycardia, sinoatrial pauses, blocks, and arrest), and may alternate with supraventricular tachyarrhythmias, in which case it is referred to as tachycardia-bradycardia syndrome. The most common SSS arrhythmias are sinus bradycardia and non-respiratory sinus arrhythmia. SSS typically occurs in the elderly. Depending on the extent of bradycardia or tachycardia, the condition may be asymptomatic or present with symptoms such as palpitations or dyspnea. More serious manifestations, such as lightheadedness and syncope, are indications for pacemaker placement.



Clinical features

Symptoms vary or may be entirely absent depending on the extent of bradycardia or tachycardia.



Symptoms or ECG findings may be inconclusive if considered on their own. Therefore, it is very important to establish a correlation between the underlying rhythm and symptom manifestation.



Management depends on the symptoms of each patient, most notably on the length of sinus pauses.