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 longer durations of time. Most of these devices can transmit the recorded
information directly to your healthcare provider. This allows him or her to analyze
the electrical activity of your heart while you are having symptoms.
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 signaling through
the heart. These tests are very helpful in diagnosing a variety of abnormal heart
rhythms and medical conditions. A standard ECG only records the heart signal for a
few seconds, and it is not portable.
An event monitor is very similar to something called a Holter monitor. This is another
portable device used to analyze the heart’s signaling. Holter monitors record continuously,
usually for about 24 to 48 hours. An event monitor does not record continuously. Instead,
it records 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
There are two main types of event monitors: symptom event monitors and memory looping
monitors. When you activate a symptom event monitor, for the next few minutes, it
records the information from the heart’s electrical signal. 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
Why might I need to use an event monitor?
Sometimes a healthcare provider may suspect that 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,
your event monitor may be used to see how well it 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 for using an event monitor?
Event monitors are completely safe. They do not cause any pain. Sometimes the sticky
patches used to attach the sensors to your chest can cause skin irritation.
How do I prepare for using 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, and 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 in order to record.
What happens while using an event monitor?
- 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 to your
- Someone will review your recording. In some cases, you may need to go see your healthcare
- 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
- When you need to use an electronic device, keep it at least 6 inches away from the
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 you can 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, more testing
maybe needed. 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
- Echocardiogram, evaluate the structure and pumping function of the heart
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 will you get the results
- Who to call after the test or procedure if you have questions or problems
- How much will you have to pay for the test or procedure