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Event Monitor

What is an event monitor?

An event monitor is a portable device used to record your heart’s electrical activity when you have symptoms. It records the same information as an electrocardiogram (ECG), but for a longer time. Most of these devices can sent the recorded information directly to your healthcare provider. This lets him or her analyze the electrical activity of your heart while you are having symptoms or shortly thereafter. 

Normally, a special group of cells begin the electrical signal to start your heartbeat. These cells are in the sinoatrial (SA) node. This node is in the right atrium, the upper right chamber of the heart. The signal quickly travels down the heart’s conducting system on the way to the ventricles, the two lower chambers of the heart. As it travels, the signal triggers nearby parts of the heart to contract. This helps the heart contract in a coordinated way.

ECGs and event monitors are used to help analyze this electrical signal in the heart. These tests help diagnose a variety of abnormal heart rhythms and medical conditions. A standard ECG only records the heart signal for a few seconds, and it's not portable.

An event monitor is similar to something called a Holter monitor. This is another portable device used to analyze the heart rhythm. Holter monitors record continuously, usually for about 24 to 48 hours. An event monitor doesn't record continuously. Instead, it records only when you activate it. Some event monitors will automatically start recording if an abnormal heart rhythm is detected. Event monitors can be worn for a month or longer.

There are two 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. However, it also records the information from a few minutes before the device was activated, so data from before, during and after the symptom will be captured.

Why might I need to use an event monitor?

Sometimes a healthcare provider may think you have an abnormal heart rhythm based on your medical history, even if your ECG looks normal. Certain abnormal heart rhythms happen infrequently and temporarily. A random ECG is unlikely to pick up your abnormal heart rhythm if this is the case. An event monitor may be a better option for you. That way, you can record your heart’s electrical activity when you are having symptoms from your abnormal rhythm. Wearing the event monitor can help determine whether you have an abnormal heart rhythm. If you do have an abnormal rhythm, the event monitor can help determine what type.

You may need to wear an event monitor if your heartbeat is abnormally fast, abnormally slow, or irregular. If you are already being treated for an abnormal heart rhythm, an event monitor may be used to see how well your treatment is working. You may need an event monitor to evaluate certain kinds of temporary symptoms, such as palpitations. You might feel that your heart is beating too hard or skipping a beat. Dizziness and fainting are other symptoms that might be signs that you need an event monitor.

What are the risks of using an event monitor?

Event monitors are completely safe. They don't cause any pain. Sometimes the sticky patches used to attach the sensors to your chest can irritate the skin. If this happens, you can ask for more sensitive electrode patches These may be less irritating on your skin.

How do I get ready to use an event monitor?

Your healthcare provider will show you how to use your event monitor. There are different types of event monitors that all work in different ways.

Cardiac memory loop monitors have sensors that attach to your chest using sticky patches. Wires connect these sensors to a monitor, which you can usually put on your belt or in your pocket. Before you put your sensors on your chest, your skin should be free 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.

Cardiac event recorders may not have sensors that attach to your chest, such as post-event recorders. Some models are handheld. Others attach to your wrist. For some of these models, you need to push the button on your wrist when you feel symptoms. In other models, you need to hold the recorder up to your chest to record.

What happens while using an event monitor?

In general:

  • If you have a cardiac loop monitor, change your sensors as instructed.

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

  • After you do this, stop moving. This will help the device get a good recording. The device should record for several minutes.

  • For some event monitors, you will need to send your recordings over the phone or the internet to your healthcare provider.

  • Someone will review your recording. In some cases, you may need to go see your healthcare provider.

  • Follow all instructions about exercise. Sweat can make the sensors come off.

  • If you can, avoid items that can disrupt the event monitor. These include magnets, metal detectors, microwave ovens, electric blankets, electric razors, electric toothbrushes, cell phones, and iPods. You will receive specific instruction at the time the monitor is placed.

  • When you need to use an electronic device, keep it at least 6 inches away from the monitor.

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

What happens after using an event monitor?

Ask your doctor about what to expect after you use 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, to see how the heart responds to exercise

  • Tilt-table test, if you have had fainting

  • Electrophysiological testing, to get more information about the heart’s electrical signal

  • Echocardiogram, evaluate the structure and pumping function of the heart

  • Implantable loop recorder, if your symptoms are infrequent and were not reproduced or captured by the event monitor

Next steps

Before you agree to the test or the procedure make sure you know:

  • The name of the test or procedure

  • The reason you are having the test or procedure

  • What results to expect and what they mean

  • The risks and benefits of the test or procedure

  • What the possible side effects or complications are

  • When and where you are to have the test or procedure

  • Who will do the test or procedure and what that person’s qualifications are

  • What would  happen if you did not have the test or procedure

  • Any alternative tests or procedures to think about

  • When and how you will get the results

  • Who to call after the test or procedure if you have questions or problems

  • How much you will have to pay for the test or procedure

Medical Reviewers:

  • Lu Cunningham
  • Quinn Goeringer PA-C
  • Steven Kang MD