Diagnosis

Your doctor will perform a physical exam and ask questions about your symptoms and medical history.

Symptoms of sick sinus syndrome — such as dizziness, shortness of breath and fainting — only occur when the heart is beating abnormally. You may not have symptoms at the time of your doctor's appointment.

To determine if your symptoms are related to problems with the sinus node and heart function, your doctor may use the following tests:

• Electrocardiogram (ECG). During this test, sensors (electrodes) are attached to your chest and legs to create a record of the electrical signals traveling through your heart. The test might show patterns that indicate sick sinus syndrome, including a fast heart rate, slow heart rate or long pause in the heartbeat after a fast heart rate.
• Holter monitor. This portable ECG 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. You may be asked to keep a diary of symptoms.
• Event recorder. This portable ECG, which may be worn up to a month, enables your doctor to correlate symptoms and heart rhythm. When you feel symptoms, you push a button, and a brief ECG recording is saved.
• Other monitors. Some personal devices, such as smart watches, offer electrocardiogram monitoring. Ask your doctor if this is an option for you.
• Implantable loop recorder. This small ECG device is implanted just under the skin of your chest and is used for continuous, long-term monitoring of your heart's electrical activity, particularly if you have infrequent 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.