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
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?
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
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 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
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
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