What is sick sinus syndrome?

Sick sinus syndrome (SSS) is a disease that affects the heart's natural pacemaker (the SA or sinoatrial node), located in the heart's upper right chamber (right atrium). With SSS, the SA node becomes damaged, and can no longer generate normal heartbeats at the normal rate. This may be a result of aging, or other health conditions that damage the SA node over time. Or it may be due to certain medicines. As a result, heartbeats may be too slow. Sometimes SSS is linked to other conditions that cause irregular heartbeats (arrhythmias) that lead to a fast heart rate. This combination of fast and slow heart rhythm is called tachy-brady syndrome (short for tachycardia-bradycardia).

Normal conduction system.

What causes sick sinus syndrome?

Any condition that can cause heart damage can damage the SA node. This includes:

• Coronary artery disease

• Past heart attack

• Atrial fibrillation

• Heart failure or cardiomyopathy (disease of the heart muscle)

• Taking certain medicines, such as beta blockers, calcium channel blockers, and digoxin, and medicines to treat arrhythmias

• Severe hypothyroidism

• Inflammatory conditions that involve the heart. These include rheumatic fever, Chagas disease, pericarditis, and myocarditis.

• Infiltrative heart diseases, such as sarcoidosis, amyloidosis, scleroderma, and hemochromatosis

• Electrolyte problems, such as high potassium levels

• Rare diseases that run in the family

• Trauma

Hypothyroidism, hypothermia, and electrolyte problems generally can be reversed.

Aging is also linked to loss of sinus node function and the development of SSS.

Who is at risk for sick sinus syndrome?

Sick sinus syndrome affects men and women equally and can occur at any age. But most cases of SSS occur in people over age 70. This is because aging tends to slow the heart rate and lower SA node function.

You are at greater risk for SSS if you have any of these:

• Coronary artery disease or history of heart attack

• Heart failure or cardiomyopathy

• Atrial fibrillation

• Inflammatory conditions that can involve the heart, such as rheumatic fever, pericarditis, Chagas disease, or myocarditis

• Infiltrative heart diseases, such as sarcoidosis, amyloidosis, hemochromatosis, or scleroderma

• Hypothyroidism

• Rare diseases that run in the family

• Trauma

You are also at greater risk of you take medicines, such as beta blockers, calcium channel blockers, or digoxin, or medicines to treat arrhythmias.

What are the symptoms of sick sinus syndrome?

You may have sick sinus syndrome with few or no symptoms. If you do have symptoms, they may include:

• Dizziness

• Fainting

• Shortness of breath, especially with exertion

• Severe tiredness (fatigue) and weakness

How is sick sinus syndrome diagnosed?

Your healthcare provider may think you have SSS based on your symptoms, but they are common in many other diseases. To diagnose your condition, your healthcare provider will do an electrocardiogram (ECG). This is a machine that records your heart's rate and rhythm. If you don't have symptoms at the time of your ECG, it may look normal.

Other possible tests include:

• An ECG while you walk on a treadmill (stress test).

• A Holter monitor. This is a recorder you wear for over 24 hours that takes an ECG. Some Holter monitors can be worn for several weeks.

• An event recorder. This is a recorder you wear over several days to weeks that samples your heart rate.

• An implantable loop recorder. This is a small heart recorder put underneath the skin over the heart. It records the heart rhythm for up to 3 years.

• Electrophysiologic testing. This is a hospital test that involves threading catheters into your heart through a vein in your groin, and electrically stimulating parts of your heart.

• Echocardiogram or ultrasound (sonogram) of your heart. This is done to check for structural heart problems.

How is sick sinus syndrome treated?

You may have SSS without symptoms and not need treatment. But if you do have symptoms and need treatment, there are choices. They include:

• Medicine change. Your healthcare provider may change your medicines if you are taking any known to cause SSS.

• Pacemaker. The most common treatment for people with symptoms that don't have a cause that can be reversed is a pacemaker. This is a small, battery-powered device that takes the place of your SA node and regulates your heart rate. A healthcare provider places a pacemaker under the skin of your chest during minor surgery. Wires are put in the heart that can keep track of the heart rate and stimulate the heartbeat when needed.

What are possible complications of sick sinus syndrome?

SSS often gets worse over time. When your heart beats too slowly, or too quickly, it can lead to complications:

• You may be injured if you pass out (faint) during an arrhythmia.

• Cardiac blood flow may be impaired. This can lead to other organ damage, such as brain and kidney function.

Living with sick sinus syndrome

The aging of your SA node causes most cases of SSS, and there’s no way to prevent that. But you can help prevent complications by learning as much as you can about the disease and working closely with your cardiologist to find the best treatment.

You can also make healthy lifestyle changes:

• Don't smoke.

• Work with your healthcare provider to keep conditions, such as high cholesterol and high blood pressure under control.

• Eat a heart-healthy diet.

• Maintain a healthy weight.

• Get regular exercise.

• Tell your healthcare provider if you have any symptoms.

Key points about sick sinus syndrome

• Sick sinus syndrome (SSS) is generally a slow heart rate, but sometimes it can be too fast.

• The most common cause is a gradual loss of SA node function that comes with age.

• You may have no symptoms, or you may have dizziness, fainting, shortness of breath, or fatigue.

• SSS may be treated by changing your medicines, treating underlying health conditions, or inserting a pacemaker.

• Not smoking, keeping your cholesterol and blood pressure under control, eating a healthy diet, maintaining a healthy weight, and getting regular exercise can help reduce the risk for SSS.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

• Know the reason for your visit and what you want to happen.

• Before your visit, write down questions you want answered.

• Bring someone with you to help you ask questions and remember what your provider tells you.

• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.

• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.

• Ask if your condition can be treated in other ways.

• Know why a test or procedure is recommended and what the results could mean.

• Know what to expect if you do not take the medicine or have the test or procedure.

• If you have a follow-up appointment, write down the date, time, and purpose for that visit.

• Know how you can contact your healthcare provider if you have questions, especially after office hours or on weekends.