Sick Sinus Syndrome

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

    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
    This disorder can be treated very effectively. If you think you may have this condition, you should contact your doctor to discuss treatment.
    Anatomy of the Heart
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  • Causes

    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 even 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. Both men and women seem to be affected equally. Although rare, infants and children can have SSS. In this case it is usually due to congenital abnormalities in their heart. Some of the risk factors for sick sinus syndrome include:
    • Age 50 and older, and especially age 65 and older
    • Some medications may worsen symptoms:
      • Calcium channel blockers
      • Beta-blockers
      • Antiarrhythmics
      • Digitalis
  • Symptoms

    Often, patients with SSS have no symptoms at all. Some patients do experience cardiac symptoms. This may include 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 or dizziness
    • Confusion or light-headedness
    • Facial flushing
    • Fatigue
    These symptoms may be caused by other, less serious health conditions. If you experience any one of them, see your doctor.
  • Diagnosis

    SSS may go undetected for some time. The symptoms are similar to ones for many disorders. Your doctor can do tests that will help to give a more definitive diagnosis. Most likely, your doctor will ask about your symptoms and medical history. A physical exam will be done. Some additional tests may include the following:
    • Electrocardiogram (ECG) —measures the electrical activity of the heart and can detect abnormal heart rhythms
    • Holter monitoring—continuous monitoring to observe episodes of tachycardia and bradycardia over an extended period of time
    • Electrophysiology study (EPS)—invasive test where electrical wires are placed into the heart to test the conduction system of the heart
  • Treatment

    For people with no symptoms, treatment may not be needed. SSS is a progressive disorder. It can further weaken the muscles of the heart in people with previous heart damage. This can lead to heart failure. As a result, people with symptoms are treated. Most treatment plans involve separate therapy for bradycardia and tachycardia. Talk with your doctor about the best plan for you. Treatment options include the following:
    Pacemaker Insertion
    A pacemaker is a small, battery-operated device. Electrodes from the pacemaker are placed in the right side of the heart. Signals are sent to the electrodes to stimulate the heart. It helps to maintain a normal heartbeat by sending electrical impulses to the heart. It is a very effective treatment of the bradycardia. People with implanted pacemakers have a very good prognosis.
    Medication
    Medication may be given to control tachycardia. It is most often given to people with a pacemaker.
  • Prevention

    Unfortunately, for most people, SSS is not preventable. I may not be caused by prior damage or scarring to the heart tissue. However, some strategies for minimizing your chance of developing this condition include:
    • Make sure to get treatment for any heart disorders you might have.
    • Make sure any doctor you see is aware of your heart conditions. Some medications should be avoided.
  • RESOURCES

    American Heart Association http://www.americanheart.org/

    Heart Rhythm Society http://www.hrsonline.org/

    CANADIAN RESOURCES

    Canadian Cardiovascular Society http://www.ccs.ca/home/index%5Fe.aspx/

    Heart and Stroke Foundation of Canada http://www.heartandstroke.com/

    References

    Adan V, Crown LA. Diagnosis and treatment of sick sinus syndrome. Am Fam Physician . 2003;67(8):1725-1738.

    DynaMed Editorial Team. Sick sinus syndrome. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed/what.php . Updated June 28, 2010. Accessed November 11, 2010.

    Heart Rhythm Society. Sick sinus syndrome. Heart Rhythm Society website. Available at: http://www.hrspatients.org.patients/heart%5Fdisorders/sick%5Fsinus/default.asp . Accessed July 28, 2005.

    Merck Manual. Sick sinus syndrome. Merck Manual website. Available at: http://www.merck.com/mrkshared/mmanual/section16/chapter205/205o.jsp . Accessed July 28, 2005.

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