Overview

Sick sinus syndrome — also known as sinus node disease or sinus node dysfunction — is a group of heart rhythm problems (arrhythmias) in which the heart's natural pacemaker (sinus node) doesn't work properly.

The sinus node is an area of specialized cells in the upper right chamber of the heart that controls the rhythm of your heart. Normally, the sinus node produces a steady pace of regular electrical impulses. In sick sinus syndrome, these signals are abnormally paced.

The heart rhythms of a person with sick sinus syndrome can be too fast, too slow, punctuated by long pauses — or an alternating combination of these rhythm problems. The syndrome is relatively uncommon, but the risk of developing it increases with age.

Many people with sick sinus syndrome eventually need a pacemaker to keep the heart in a regular rhythm.

Source: http://www.mayoclinic.com

Symptoms

Most people with sick sinus syndrome initially have few or no symptoms. In some cases, symptoms come and go.

When they occur, sick sinus syndrome signs and symptoms might include:

• Slower than normal pulse (bradycardia)
• Fatigue
• Dizziness or lightheadedness
• Fainting or near fainting
• Shortness of breath
• Chest pains
• Confusion
• A sensation of rapid, fluttering heartbeats (palpitations)

When to see a doctor

If you have lightheadedness, dizziness, fainting, fatigue, shortness of breath or palpitations, talk to your doctor. Many medical conditions can cause these signs and symptoms — including sick sinus syndrome — and it's important to identify the problem.

Source: http://www.mayoclinic.com

Causes

Your heart is made up of four chambers — two upper (atria) and two lower (ventricles). The rhythm of your heart is normally controlled by the sinus node, an area of specialized cells in the right atrium.

This natural pacemaker produces the electrical impulses that trigger each heartbeat. From the sinus node, electrical impulses travel across the atria to the ventricles, causing them to contract and pump blood to your lungs and body.

If you have sick sinus syndrome, your sinus node isn't functioning properly, causing your heart rate to be too slow (bradycardia), too fast (tachycardia) or irregular.

Types of sick sinus syndrome and their causes include:

• Sinoatrial block. Electrical signals move too slowly through the sinus node, causing an abnormally slow heart rate.
• Sinus arrest. The sinus node activity pauses, causing skipped beats.
• Bradycardia-tachycardia syndrome. The heart rate alternates between abnormally fast and slow rhythms, usually with a long pause (asystole) between heartbeats.

What makes the sinus node misfire?

Diseases and conditions that cause scarring or damage to your heart's electrical system can be the reason. Scar tissue from a previous heart surgery also can be the cause, particularly in children. Rarely, the cause can be genetic.

Sick sinus syndrome can be unmasked by medications, such as calcium channel blockers or beta blockers used to treat high blood pressure, or by other conditions causing the heartbeat to be slower or faster than normal. In most cases, the sinus node doesn't work properly because of age-related wear and tear to the heart muscle.

Source: http://www.mayoclinic.com

Diagnosis

Symptoms of sick sinus syndrome — such as dizziness, shortness of breath and fainting — are symptoms of numerous conditions. However, in sick sinus syndrome, these symptoms only occur when the heart is beating abnormally.

To diagnose and treat sick sinus syndrome, your doctor will conduct a physical exam and gather a medical history. He or she will seek to connect your symptoms to an abnormal heart rhythm.

Testing for sick sinus syndrome might include:

• Electrocardiogram (ECG). During this test, sensors (electrodes) are attached to your chest and limbs to create a record of the electrical signals traveling through your heart. The test might show patterns that indicate sick sinus syndrome, including fast heart rate, slow heart rate or a long pause in the heartbeat (asystole) after a fast heart rate.
• Holter monitor. This portable device is carried in your pocket or in a pouch on a belt or shoulder strap. It automatically records your heart's activity for 24 to 72 hours, which provides your doctor with an extended look at your heart rhythms.

• Event recorder. This portable electrocardiogram device can also be carried in your pocket or worn on a belt or shoulder strap for home monitoring of your heart's activity. You might be asked to use this device to use for up to a month.

  When you feel symptoms, you push a button, and a brief ECG recording is saved. This allows your doctor to see your heart rhythm at the time of your symptoms, which can help pinpoint sick sinus syndrome.

• Implantable loop recorder. This small device is implanted just under the skin of your chest and is used for continuous, long-term monitoring of your heart's electrical activity. An implantable loop recorder may be worn from months to years.

  This device is automatically triggered by an irregular heart rhythm (arrhythmia) or you can trigger it when you feel symptoms.

Electrophysiologic testing

This test is rarely used to screen for sick sinus syndrome. However, in some cases, it can help check the function of your sinus node, as well as other electrical properties of your heart.

During this test, thin, flexible tubes (catheters) tipped with electrodes are threaded through your blood vessels to various spots along the electrical pathways in your heart. Once in place, the electrodes can precisely map the spread of electrical impulses during each beat and may identify the source of heart rhythm problems.

Source: http://www.mayoclinic.com

Complications

When your heart's natural pacemaker isn't working properly, your heart can't perform as efficiently as it should. This can lead to:

• Atrial fibrillation, a chaotic rhythm of the upper chambers of the heart
• Heart failure
• Stroke
• Cardiac arrest

Lifestyle and home remedies

To keep your heart as healthy as possible and to treat or eliminate risk factors that can lead to heart disease:

• Exercise and eat a healthy diet. Live a heart-healthy lifestyle by exercising regularly and eating a healthy, low-fat diet that's rich in fruits, vegetables and whole grains and low in saturated fats and simple sugars.
• Maintain a healthy weight. Being overweight increases your risk of developing heart disease.
• Keep blood pressure and cholesterol under control. Make lifestyle changes and take medications as prescribed to correct high blood pressure (hypertension) or high cholesterol.
• Don't smoke. If you smoke and can't quit on your own, talk to your doctor about strategies or programs to help you break a smoking habit.
• If you drink, do so in moderation. For some conditions it's recommended that you completely avoid alcohol. Ask your doctor for advice specific to your condition. If you can't control your alcohol use, talk to your doctor about a program to quit drinking and manage other behaviors related to alcohol abuse.
• Don't use illegal drugs. Talk to your doctor about an appropriate program for you if you need help ending illegal drug use.
• Control stress. Avoid unnecessary stress and learn coping techniques to handle normal stress in a healthy way.
• Go to scheduled checkups. Have regular physical exams and report any signs or symptoms to your doctor.

Source: http://www.mayoclinic.com

Risk factors

Sick sinus syndrome can occur at all ages, even infancy. Because it usually develops over many years, it's most common in people over age 65.

In rare cases, sick sinus syndrome can be associated with certain conditions such as muscular dystrophy and other diseases that may affect the heart.

Source: http://www.mayoclinic.com