Sick sinus syndrome
Sick sinus syndrome
Sick sinus syndrome is the name for a group of heart rhythm problems (arrhythmias) in which the sinus node — the heart's natural pacemaker — 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. A person with sick sinus syndrome may have heart rhythms that are too fast, too slow, punctuated by long pauses — or an alternating combination of all of these rhythm problems.
Sick sinus syndrome is relatively uncommon, but the risk of developing sick sinus syndrome increases with age. Many people with sick sinus syndrome eventually need a pacemaker to keep the heart in a regular rhythm.
Most people with sick sinus syndrome initially have few or no symptoms. In some cases, symptoms may come and go.
When they do occur, sick sinus syndrome symptoms may include:
Many of these signs and symptoms are caused by reduced blood flow to the brain when the heart beats too fast or too slowly.
When to see a doctor
Your heart is made up of four chambers — two upper chambers (atria) and two lower chambers (ventricles). The rhythm of your heart is normally controlled by the sinoatrial node (SA node) — or sinus node — an area of specialized cells located 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 out to your lungs and body.
If you have sick sinus syndrome, your sinus node isn't functioning properly, so your heart rate may be too slow (bradycardia) or too fast (tachycardia) or irregular.
Types of sick sinus syndrome and their causes include:
What makes the sinus node misfire?
A normal heartbeat begins when a tiny cluster of cells called the sinus node sends an electrical signal (1). The signal then travels through the atria and passes through another group of cells called ...
Sick sinus syndrome can occur in people of all ages, even infants. Because it usually develops slowly, over many years, it's most common in people around age 70.
In rare cases, sick sinus syndrome may also be associated with certain conditions such as muscular dystrophy and other diseases that may affect the heart.
When your heart's natural pacemaker isn't working properly, your heart can't perform as efficiently as it should. This can lead to a very slow heart rate, which may cause fainting. In rare cases, long periods of slow heart rate or fast heart rate can keep your heart from pumping enough blood to meet your body's needs — a condition called heart failure.
If you have a type of sick sinus syndrome called bradycardia-tachycardia syndrome, you may also be at a higher risk of developing a blood clot in your heart that may lead to a stroke. That's because the fast heart rhythm that occurs in bradycardia-tachycardia syndrome is often atrial fibrillation. Atrial fibrillation is a chaotic rhythm of the upper chambers of the heart that can cause blood pooling in the heart. Blood clots are more likely to form when blood flow through the heart is altered in any way. A blood clot can break loose and travel to the brain, causing a stroke.
Preparing for your appointment
Symptoms of sick sinus syndrome, if present at all, may be so mild that you don't realize they're cause for concern. For this reason, sick sinus condition may not be diagnosed until it's in an advanced stage, when the risk of complications is greater. Call your family doctor or general practitioner if you have symptoms of sick sinus syndrome. In some cases when you call to set up an appointment, you may be referred to a doctor who specializes in the diagnosis and treatment of heart conditions (cardiologist).
Here's some information to help you prepare for your appointment.
What you can do
For sick sinus syndrome, some basic questions to ask your doctor include:
In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment at any time that you don't understand something.
What to expect from your doctor
What you can do in the meantime
If exercise makes your symptoms worse, avoid exercise until you've been seen by your doctor.
Tests and diagnosis
Symptoms of sick sinus syndrome — such as dizziness, shortness of breath and fainting — are also symptoms of many other diseases and conditions. However, in sick sinus syndrome, these symptoms only occur when the heart is beating abnormally. In order to diagnose and treat sick sinus syndrome, your doctor will need to establish a connection between your symptoms and an abnormal heart rhythm.
Treatments and drugs
Treatment for sick sinus syndrome focuses on eliminating or reducing unpleasant symptoms. If you aren't bothered by symptoms, you may only need regular checkups to monitor your condition. For people who are bothered by symptoms, the treatment of choice is usually an implanted electronic pacemaker.
Pacing the heart
The type of pacemaker you need depends on the type of irregular heart rhythm you're experiencing. Some rhythms can be treated with a single-chamber pacemaker, which uses only one wire (lead) to pace one chamber of the heart - in this case, the atrium. However, most people with sick sinus syndrome benefit from dual-chamber pacemakers, in which one lead paces the atrium and one lead paces the ventricle.
You'll be able to resume normal or near-normal activities after you recover from pacemaker implantation surgery. The risk of complications, such as swelling or infection in the area where the pacemaker was implanted, is small.
Additional treatments for fast heart rate
Last Updated: 2011-05-20
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