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sick sinus syndrome

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Sick sinus syndrome (SSS) is a set of symptoms caused by abnormal electrical activity in a part of the heart called the sinus node.

What is going on in the body? 
A collection of nerves in the heart form the heart's electrical system. This system is what keeps the heart beating. A part of this system, called the sinus node, usually generates the signal that causes the heart to beat. When the sinus node is damaged or doesn't function right, the heart may beat too slowly or even stop beating for a period of time. Irregular heartbeats, called arrhythmias, can also occur. Sick sinus syndrome refers to the symptoms seen when the sinus node fails to work properly.

What are the signs and symptoms of the condition? 
Symptoms of sick sinus syndrome often come and go, because the electrical system of the heart usually only functions abnormally at certain times. The common symptoms of SSS include: What are the causes and risks of the condition? 
In most cases, no cause can be found for sick sinus syndrome. SSS is usually seen in middle-aged and elderly people. Possible causes of sick sinus syndrome include:
  • blockages in the heart arteries caused by coronary artery disease
  • high blood pressure
  • almost any condition affecting the heart
  • medications, such as the blood pressure and heart medications atenolol and diltiazem. These medications may "bring out" or worsen this condition in a person who before had few or no symptoms.
What can be done to prevent the condition? 
Most cases of sick sinus syndrome cannot be prevented. Careful selection of blood pressure and heart medications may avoid symptoms. Treatment of heart disease may help prevent the development of this syndrome in some cases.

How is the condition diagnosed? 
Diagnosis of sick sinus syndrome begins with a history and physical examination. A heart tracing, called an electrocardiogram or ECG, can confirm the diagnosis. This test records the electrical activity in the heart, which is abnormal when symptoms occur.

Because symptoms come and go, a Holter monitor is often used to track the electrical activity of the heart over a longer period of time. This monitor can be worn for 24 hours or more, so that a heart tracing can be obtained during symptoms. If the abnormal electrical activity of sick sinus syndrome is seen on the heart tracing when symptoms occur, the diagnosis can be made.

What are the long-term effects of the condition? 
A person with sick sinus syndrome can injure himself or herself during a fainting episode. An individual with certain arrhythmias has an increased risk of blood clots, which can cause a stroke. There is also the rare risk of sudden death that can occur if the heart stops beating for a long period of time. Treatment can avoid most of these long-term effects if the diagnosis is made in time.

What are the risks to others? 
Sick sinus syndrome is not contagious and poses no risks to others. Those who pass out may injure others if they are driving or performing other potentially dangerous activities.

What are the treatments for the condition? 
If a person with sick sinus syndrome is having significant symptoms, a permanent device to help control the heartbeat is often used. This device is called a pacemaker. This device causes the heart to beat by creating tiny bursts of electricity that are sent to the heart. It only "fires" when it is needed, but can be lifesaving.

Sometimes, medications, such as amiodarone, are used to control arrhythmias. Blood thinners, such as warfarin, may be used to help prevent blood clots in those with certain arrhythmias.

What are the side effects of the treatments? 
Discharges from a pacemaker can be uncomfortable. The device can occasionally misfire and cause heartbeat problems. Medications used to control arrhythmias may cause allergic reactions, stomach upset, and new arrhythmias. Medications that thin the blood may cause allergic reactions and serious abnormal bleeding.

What happens after treatment for the condition? 
Most people do very well after they receive a pacemaker. Though it may occasionally "fire" and cause discomfort, the pacemaker helps prevent dangerous symptoms, such as dizziness and fainting. Someone with other heart disease or arrhythmias usually needs lifelong treatment for these conditions.

How is the condition monitored? 
The doctor will recommend regular visits to monitor symptoms and treat any heart disease. Pacemakers need to be checked periodically to make sure they are working properly. Pacemakers also have a battery that needs to be replaced from time to time. Blood tests are needed to check the "thickness" of the blood when a person is on blood-thinning medications. Other medications may also need monitoring, which can include blood tests. Any new or worsening symptoms should be reported to the doctor.

Author: Eric Berlin, MD
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Potential conflict of interest information for reviewers available on request

This website and article is not a substitute for independent professional advice. Nothing contained in this website is intended to be used as medical advice and it is not intended to be used to diagnose, treat, cure or prevent any disease, nor should it be used for therapeutic purposes or as a substitute for your own health professional's advice.  All Health and any associated parties do not accept any liability for any injury, loss or damage incurred by use of or reliance on the information.


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