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by Borowski M
(SSS; Bradycardia-Tachycardia Syndrome; Sinus Node Dysfunction)


The sinus node is a group of cells in the heart that make the heart beat (contract) in a regular pattern. Sick sinus syndrome is a group of symptoms that suggest the sinus node is not working properly. Sick sinus syndrome can lead to:

  • Bradycardia —abnormally slow heart rate
  • Tachycardia —abnormally fast heart rate
  • Bradycardia-tachycardia—the heart alternates between fast and slow rates
  • Missed or skipped beats

Sick sinus syndrome usually worsens over time, though some may never know they have it. However, sick sinus syndrome can eventually lead to major heart health complications.

Anatomy of the Heart
Copyright © Nucleus Medical Media, Inc.


The sinus node is the pacemaker of the heart. It creates and sends electrical signals that stimulate the heart to contract in a regular pattern. The sinus nodes ability to function may be disrupted by:

  • Problems within the heart tissue—such as damage of the sinus node, long-term illness, or surgical injury
  • Outside factors acting on the heart tissue—such as exposure to toxins or certain drugs/medications

Risk Factors

Sick sinus syndrome is fairly rare. It occurs most often in elderly people and those who have had damage to the heart tissue. It can rarely occur in infants and children due to congenital abnormalities in the heart.


At first, sick sinus syndrome may not have symptoms or the symptoms may come and go. Since the syndrome can cause a variety of problems, symptoms will be different from person to person.

Some people can feel irregular heart beats as flutters in their chest, very rapid heart beats, or missed beats. If the irregular heart patterns are severe enough to affect blood flow to the body symptoms may include:

  • Chest pain
  • Fainting
  • Confusion or lightheadedness
  • Facial flushing
  • Fatigue

These symptoms may be caused by other, less serious health conditions. If you experience any one of them, see your doctor.


Sick sinus syndrome may go undetected for some time if it is not causing symptoms. Your doctor will ask about your symptoms and medical history. A physical exam will be done. To examine the electrical activity of your heart your doctor order one or more of the following test:

  • ECG —can detect abnormal heart rhythms during testing
  • Holter monitoring—a device is placed for 24 to 48 hours while you move through your normal day to look for temporary abnormal heart patterns
  • Electrophysiology study (EPS)—invasive test that passes electrical wires to the heart to measure activity, used more often with severe problems


For people with no symptoms, treatment may not be needed. Sick sinus syndrome can eventually increase the risk of other cardiovascular issues such as atrial fibrillation , heart failure , heart attack, or stroke. As a result, your doctor will monitor your overall heart health.

Treatment may be needed if the irregular heart patterns are disrupting the flow of blood through the heart. The exact treatment will depend on the individual's needs. Options include the following:

  • Pacemaker —A device may be inserted that sends electrical impulses to the heart to stimulate a normal rhythm when needed. Often used with slow heart rhythm.
  • Medication—May help to control fast heart rates or stimulate slow rates.


For most people, sick sinus syndrome is not preventable.


American Heart Association 

Heart Rhythm Society 


Canadian Heart Rhythm Society 

Heart and Stroke Foundation of Canada 


Semelka M, Gera J, Usman S. Sick sinus syndrome: a review. Am Fam Physician. 2013;87(10):691-696.

Sick sinus syndrome. EBSCO DynaMed Plus website. Available at:  . Updated December 8, 2015. Accessed November 28, 2017.

Sick sinus syndrome. Heart Rhythm Society website. Available at: Accessed November 28, 2017.

Sinus node dysfunction. Merck Manual Professional Version website. Available at: Updated September 2017. Accessed November 28, 2017.

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