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2288 pages added, reviewed or updated during the last month (last updated: 19/4/2021)

2288 pages added, reviewed or updated during the last month (last updated: 19/4/2021)

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sick sinus syndrome

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This is a condition that is commonly seen in the elderly

  • sick sinus syndrome is an irreversible dysfunction of the sinus node
  • sick sinus syndrome is characterised by impaired impulse formation, which is often the result of chronic fibrotic degeneration or calcification of the sinus node and/or the surrounding atrial tissues
  • prevalence of sick sinus syndrome is thought to be about 0.03% of the whole population, and increases with age
  • characteristic of this condition are long intervals between consecutive P waves (greater than 2 seconds) on the ECG. The pauses between P waves may be an exact multiple of the basic sinus interval (sino-atrial block) or not (sinus-arrest). The prognosis of both conditions is similar.

The sinus pauses and sinus bradycardia may allow cardiac tachyarrhythmias to emerge. The TACHY-BRADY syndrome occurs when there is a combination of fast and slow supraventricular rhythms.

Sick Sinus (Bradycardia-Tachycardia) Syndrome and the ECG (2)

  • in patients with sick sinus syndrome, various types of arrhythmias may be observed at different times
  • a single ECG is generally inadequate for the diagnosis of sick sinus syndrome
  • definitive diagnosis is made by electrophysiologic study. However, several ECGs recorded at different times may strongly suggest the diagnosis of sick sinus syndrome
  • ECG abnormalities in patients with Sick Sinus Syndrome

For more information and example ECGs in Sick Sinus Syndrome then click here


  1. NICE (February 2005).Dual-chamber pacemakers for symptomatic bradycardia due to sick sinus syndrome and/or atrioventricular block
  2. (Accessed 11/6/2020)


Last edited 06/2020