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Bradycardia - tachycardia syndrome

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

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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


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)


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