Sick sinus syndrome

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
  • inappropriate sinus bradycardia (not related to medication use or the patient's physiological status)
  • sinus arrest.
  • sinoatrial exit block.
  • atrial arrhythmias: atrial flutter, atrial fibrillation
  • consecutive atrial tachycardias and bradycardias (bradycardia-tachycardia syndrome)
  • Atrioventricular (AV) blocks
  • inadequate increase of heart rate: failure to increase heart rate despite pain, fever, etc
  • failure to increase heart rate during exercise.

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

Reference:

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