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Sick Sinus Syndrome

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Synonyms: Sinus node disease, Sinus node dysfunction

The umbrella term for abnormal heart rhythm is called as sick sinus syndrome (SSS) or the sinus node dysfunction (SND). These arrhythmias are caused by the improper functioning of the sinus node. The sinus node is the natural pacemaker of the heart.

What is the Sinus Node?

The sinus node is an area within the heart that contains specialized cells. It is located in the upper right chamber of the heart that controls heart rhythm. The pace at which normal electrical impulses are passed within the heart is maintained by the sinus node.

The sinus nodes generate impulses that spread through the atria and ventricles. This helps in the normal contraction of the muscles that leads to 60 to 100 beats/minute. During stress, physical exercise or high fever, the heart rate may be high. Similarly, during sleep or in some well-trained athletes, the heart beats or sinus node impulses may slow down to less than 60 beats/minute. However, this is considered as normal and does not fall under the sick sinus syndrome.

What is Sick Sinus Syndrome?

When the normal electrical impulses become abnormally paced, it leads to sick sinus syndrome. A person with sick sinus syndrome develops heart rhythms that are either too fast (inappropriate tachycardia), too slow (bradycardia) or have long pauses between each rhythm (sinus pause or sinus arrest). Some may suffer from a combination of these heart rhythm problems (bradycardia-tachycardia syndrome).

SSS worsens with advancing age. It affects men and women equally.

Who Is At Risk of Developing Sick Sinus Syndrome?

Some of the risk factors that increase one’s chances of developing sick sinus syndrome include:

  • Advanced age of 65 years and above, when the sinus node cells decrease in number due to the natural wear and tear
  • Any person who has suffered from myocardial infraction causing damage to heart node
  • A person who is on medications for the treatment of tachycardia such as verapamil, diltiazem, atenolol, etc.
  • People with hypothyroidism
  • A person suffering from sleep apnea
  • Children who suffer from congenital heart defect or have undergone the corrective surgery for the same
  • In some rare cases, people suffering from muscular dystrophy, amyloidosis or diphtheria can develop SSS

Symptoms of Sick Sinus Syndrome

Mild sick sinus syndrome does not lead to any symptoms or feeling of sickness. In some people, it may lead to mild illness. When the disease advances or becomes severe, it may lead to the following symptoms:

  • Palpitations
  • Fainting or dizziness
  • Fatigue
  • Weakness
  • Mental confusion due to decrease in blood supply to the brain
  • Chest pain
  • Erratic or disturbed sleep

Diagnosis of Sick Sinus Syndrome

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The doctor will take a complete medical history as well as a detailed account of the symptoms experienced by the patient. After conducting a physical checkup, the doctor will suggest some diagnostic tests. These tests include:

  • ECG to measure electrical activity of the heart. However, SSS may come and go, so a normal ECG may not able able to catch the abnormal heart rhythm every time. Thus, the doctor may recommend a Holter monitor to measure the heart rhythm for the next 24 to 48 hours.
  • A tilt table test may be carried out for diagnosing cardioinhibitory and vasodepressor forms of SSS.

Treatment for Sick Sinus Syndrome

The asymptomatic sick sinus syndrome does not require any treatment. However, in case the condition worsens, the doctor may suggest a pacemaker for bradycardia. Tachycardia is treated with the help of medications. In case, both these conditions are presented simultaneously, the doctor may suggest fitting an artificial pacemaker, before starting on medication that help control tachycardia.

Pacemakers have helped improve the prognosis for patients with sick sinus syndrome. However, pacemakers are not the cure, but function as an effective treatment for the condition. However, those who are too weak to undergo a surgery, have an uncertain prognosis. They may suffer from sudden cardiac arrest that may prove to be fatal. If left untreated, it may lead to heart failure, blood clots and even stroke. Speak to your healthcare provider for more details and follow the medical advice best suited in your condition.

Written by: Saptakee sengupta
Date last updated: April 07, 2015

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