Sick sinus syndrome

Sick sinus syndrome — also known as sinus node disease or sinus node dysfunction — is the name for a group of heart rhythm problems (arrhythmias) in which the sinus node — the heart's natural pacemaker — doesn't work properly.

The sinus node is an area of specialized cells in the upper right chamber of the heart that controls the rhythm of your heart. Normally, the sinus node produces a steady pace of regular electrical impulses. In sick sinus syndrome, these signals are abnormally paced.

A person with sick sinus syndrome may have heart rhythms that are too fast, too slow, punctuated by long pauses — or an alternating combination of all of these rhythm problems. Sick sinus syndrome is relatively uncommon, but the risk of developing sick sinus syndrome increases with age.

Many people with sick sinus syndrome eventually need a pacemaker to keep the heart in a regular rhythm.

Symptoms Causes Risk factors Complications

Most people with sick sinus syndrome initially have few or no symptoms. In some cases, symptoms may come and go.

When they do occur, sick sinus syndrome symptoms may include:

  • Slower than normal pulse (bradycardia)
  • Fatigue
  • Dizziness or lightheadedness
  • Fainting or near fainting
  • Shortness of breath
  • Chest pains
  • A sensation of rapid, fluttering heartbeats (palpitations)

Many of these signs and symptoms are caused by reduced blood flow to the brain when the heart beats too fast or too slowly.

When to see a doctor

If you have spells of lightheadedness, dizziness, fainting, fatigue, shortness of breath or palpitations, talk to your doctor. Many medical conditions can cause these signs and symptoms — including sick sinus syndrome — and it's important to identify the problem.

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