Sick sinus syndrome: Difference between revisions

'''Sick sinus syndrome''' (SSS) or '''sinus node dysfunction''' (SND) refers to any condition where the [[Sinoatrial node|SA node]] is dysfunctional. This causes intermittent [[sinus bradycardia]] (< 40 bpm when awake), sinus pauses (pauses <3 seconds), [[sinus arrest]] (pauses >3 seconds), tachycardia-bradycardia syndrome, [[chronotropic incompetence]], or [[Sinoatrial block|SA block]]. Patients present with intermittent complaints of fatigue, dizziness, palpitations, syncope, etc.  

'''Tachycardia-bradycardia syndrome''', usually called simply '''tachy-brady syndrome''', refers to when a patient both has alternating atrial tachyarrhythmias (like [[atrial fibrillation]]) and symptomatic sinus bradycardia. This occurs in 50% of those with SSS. The atrial tachyarrhythmia may spontaneously convert to sinus rhythm, but because the sinus node is sick, there may be a pause before the sinus node kicks in, which can be symptomatic.  

The syndrome can cause dizziness, syncope, palpitations, and chest pain. Pacemaker implantation is usually necessary, especially if the atrial tachyarrhythmia has a rapid ventricular response. The ideal treatment would be rate-limiting drugs, like [[beta blockers]] or [[calcium channel blockers]], but these would worsen the sinus bradycardia when it occurs. Implantation of a pacemaker (which prevents symptomatic bradycardia) can allow for administration of rate-limiting drugs to reduce the rapid ventricular response of the tachyarrhythmia, alleviating the symptoms.