How an event monitor works

An event monitor uses small sticky pads (electrodes) stuck to your chest. These connect by wires to the monitor device. The device records the same kind of information as an electrocardiogram (ECG). But it does it for longer periods of time, usually at least 1 minute at a time.

There are 2 main types of event monitors: symptom event monitors and memory looping monitors. When you activate a symptom event monitor, it records the information from the heart’s electrical signal for a few minutes. A memory looping monitor does the same thing. But it also records the information from a few minutes before the device was activated. This is so data from before, during, and after the symptom will be captured. Most of these devices can send the information right to your healthcare provider. For others, data must be downloaded.

Some event monitors don't use wires. Instead, the monitor is placed directly on the skin to record heart activity.

Why an event monitor is used

A healthcare provider may think that you have an abnormal heart rhythm based on your health history, even if your ECG looks normal. Some abnormal heart rhythms happen less often and for only a short time. In this case, an ECG is not likely to pick up the abnormal heart rhythm. An event monitor may be a better choice for you. That way, you can record your heart’s electrical activity when you are having symptoms. The event monitor can also help show what type of abnormal rhythm you have. It's best for rhythm abnormalities that happen now and then or that are caused by certain symptoms. 

You may need to wear an event monitor if:

• Your heartbeat is too fast, too slow, or irregular

• You have symptoms, such as palpitations, dizziness, or fainting, or feel your heart is beating too hard or skipping a beat

• Your healthcare provider wants to check how well the treatment for an abnormal heart rhythm is working. You may have to wear a monitor after a coronary ablation or cardioversion to see that your heart is still in a normal rhythm with these types of treatments.

• You have had an open heart surgery, such as a heart valve replacement or repair or bypass grafting. The heart muscle can become irritated and more likely to have irregular heart rhythms as you recover at home.

Risk of using an event monitor

Event monitors are generally very safe. They don’t cause any pain. In some cases, the sticky patches used to attach the sensors to your chest can cause skin irritation and blistering. Many event monitor companies have alternative electrodes that are better for sensitive skin. Contact your healthcare provider if you have skin irritation.

Getting your event monitor

Your healthcare provider will show you how to use your event monitor. Different types of event monitors work in different ways. Memory looping monitors have sensors that attach to your chest using sticky patches. Wires connect these sensors to a monitor. You can usually put the monitor on your belt or in your pocket.

Before you put your sensors on your chest, your skin should be clean of oils, creams, and sweat. Clean your skin before putting them on. You may need to shave the area before applying. A technician will show you how to place the electrodes. Or the monitor may be mailed to your home with instructions for using it. Follow all instructions about exercise. Sweat can make the sensors come off. If you have a cardiac memory looping monitor, change your sensors as instructed.

You may need to wear your event monitor for several days or up to a month. You will also need to keep a diary while using your event monitor. Record any symptoms when they happen, and note what you were doing at the time.

When it’s time to record an event

• When you have a symptom, push the button to start recording. (Some start recording automatically when an abnormal rhythm is detected.)

• Stop moving. This will help the device get a good recording. The device should record for several minutes.

• After the event, write down the time, your symptoms, and what you were doing when the event happened.

After recording an event

For some event monitors, you will need to send your recordings over the phone to your healthcare provider. Someone will review your recording. In some cases, you may need to go see your healthcare provider.

Preventing problems

Some electronic devices can disrupt the monitor. If you can, don't use these during the time you’re wearing the monitor. But when you need to use an electronic device, keep it at least 6 inches away from the monitor. This includes things, such as:

• Cell phones

• Electric blankets

• Electric razors

• Electric toothbrushes

• iPods

• Magnets

• Metal detectors

• Microwave ovens

Note: Don't use large motors or construction equipment near the monitor. They can cause interference. The vibrations that can be mistaken as irregular heart rhythms by the monitor.

Treatment after an event monitor

After a few readings, you may be able to stop wearing your event monitor. Your healthcare provider may use those readings to start your treatment. In some cases, you may need more testing. Follow-up tests might include:

• Exercise stress test. This shows how your heart responds to exercise and how well it handles increased oxygen demands.

• Tilt table test. This may be done if you have had fainting.

• Electrophysiology testing. This invasive procedure can give more details about your heart’s electrical signal.

• Echocardiogram. This is done to evaluate the structure and pumping function of your heart and its valves.