Sick Sinus Syndrome

(SSS; Bradycardia-Tachycardia Syndrome; Sinus Node Dysfunction)


Sick sinus syndrome (SSS) is not one specific disease. It is the term is used to describe several heart rhythm disorders. Sick sinus syndrome disorders include:
  • Bradycardia —abnormally slow heart rate
  • Tachycardia —abnormally fast heart rate
  • Bradycardia-tachycardia—the heart alternates between too fast and too slow
Anatomy of the Heart
Copyright © Nucleus Medical Media, Inc.


SSS is caused by a problem with the electrical signals of the heart. The problem begins in an area of the heart called the sinoatrial (SA) node. This node is considered to be the heart’s natural pacemaker. When the SA node is defective, the heart’s rhythms become abnormal. The dysfunction in the SA node can be due to:
  • Intrinsic causes (problems within the heart tissue), such as degeneration of the sinus node, long-term illness, or surgical injury
  • Extrinsic causes (outside factors acting on the heart tissue), such as exposure to toxins or certain pharmacological agents

Risk Factors

SSS is fairly rare. It occurs most often in elderly people and those who have had damage to the heart tissue. Although rare, infants and children can have SSS. In this case, it is usually due to congenital abnormalities in the heart. Certain medications may worsen symptoms.


Often, SSS doesn't have symptoms. Some may experience a period of very rapid heart beats followed by very slow heart rate. Many of the symptoms of sick sinus disorder are mild and nonspecific. Some symptoms associated with SSS include:
  • Heart palpitations
  • 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.

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