Sick sinus syndrome is a type of atrial fibrillation where the heart does not beat as it should. In atrial fibrillation, the heart’s sinoatrial node (SA node) sends irregular electrical signals, causing the upper chambers of the heart (the atria) to quiver (fibrillate), and the heart may beat too quickly or too slowly. When the heart is not beating as it should, blood clots can form in the heart’s left atrial appendage. This is why atrial fibrillation is a significant risk factor for stroke. (Media provided courtesy of Boston Scientific. © 2015 Boston Scientific Corporation or its affiliates. All rights reserved.)

The sinus node of the heart sits in the right upper chamber (the right atrium) of the heart. The sinus node is the heart’s natural pacemaker. It is responsible for stimulating the heart to beat in a normal rhythm. When the sinus node is not working correctly, the heart can beat faster or more slowly, or it may beat erratically. This is a type of atrial fibrillation (Afib or AF) known as sick sinus syndrome, sinus node disease or sinus node dysfunction.

Tachy-Brady Syndrome

One symptom of sick sinus syndrome is a specific irregular heartbeat known as tachycardia-bradycardia syndrome, or tachy-brady for short. In this situation, the heart may beat too quickly (tachycardia), then too slowly (bradycardia). Complications can include loss of consciousness and ultimately a higher risk of stroke.

Who Is Affected by Tachy-Brady Syndrome?

Anyone can be affected by sick sinus syndrome; however, like many forms of atrial fibrillation, the risk of developing it becomes greater as a person ages.

How Is Tachy-Brady Syndrome Diagnosed?

The first step your doctor will take in diagnosing tachy-brady (and in diagnosing many heart problems) is an electrocardiogram, also known as an EKG or ECG. This test measures the heart’s electrical activity by using small sensors that are temporarily affixed to the chest with an adhesive.

Electrocardiograms are an extremely important tool. However, because not all patients experience atrial fibrillation symptoms during their EKG, other tests may be recommended. These include a Holter monitor, which is a portable device a person wears for 24 to 48 hours that continuously records the activity of the heart. Another type of electrocardiogram is the event recorder, which can be worn for up to a month. When the person feels symptoms, he or she presses a button that activates the device to record the heart’s activity during that time. A third type, meant to work for several months or more, is an implantable loop recorder. As the name suggests, the device is implanted in the chest just below the skin, and provides long-term heart monitoring. Should an abnormal heart rhythm take place, the device is activated and begins recording.

Electrophysiologic (or EP) testing also can be used to check the function of the sinus node. EP testing is not commonly used to diagnose sick sinus syndrome, although it is often used to diagnose serious electrical problems of the heart. In this test, thin and flexible tubes (catheters) are run through the blood vessels to various locations in the heart. Electrodes at the tips of the catheters record the electrical activity in the heart, providing the medical team with information about the heart’s performance.

How Is Tachy-Brady (Sick Sinus) Syndrome Treated?

Sick sinus syndrome usually will not resolve on its own and will require medical treatment. Your healthcare team may recommend a pacemaker to help the heart beat in a stable rhythm. Medications may also help control sick sinus syndrome, either in conjunction with a pacemaker or, in some cases, instead of it. You can learn more about the treatments for tachy-brady syndrome and other forms of atrial fibrillation here.