What Are Holter and Event Monitors?
Holter and event monitors are medical devices that
record the heart's electrical activity. Doctors most often use these monitors
to diagnose
arrhythmias
(ah-RITH-me-ahs). These are problems with the speed or rhythm of the heartbeat.
During an arrhythmia, the heart can beat too fast, too slow, or
irregularly.
Holter and event monitors also are used to detect
silent myocardial ischemia (is-KE-me-ah). In this condition, not enough
oxygen-rich blood reaches the heart muscle. "Silent" means that no symptoms
occur.
These monitors also can check whether treatments for
arrhythmia and silent myocardial ischemia are working.
This article focuses on using Holter and event
monitors to diagnose problems with the heart's speed or rhythm.
Overview
Holter and event monitors are similar to an
EKG
(electrocardiogram). An EKG is a simple test that detects and records the
heart's electrical activity. It's the most common test for diagnosing a heart
rhythm problem.
However, a standard EKG only records the heartbeat
for a few seconds. It won't detect heart rhythm problems that don't occur
during the test.
Holter and event monitors are small, portable
devices. You can wear one while you do your normal daily activities. This
allows the monitor to record your heart for a longer time than an EKG.
Some people have heart rhythm problems that only
occur during certain activities, such as sleep or physical exertion. Using a
Holter or event monitor increases the chance of recording these problems.
Although similar, Holter and event monitors aren't
the same. A Holter monitor records your heart's electrical activity the entire
time you're wearing it. An event monitor only records your heart's electrical
activity at certain times while you're wearing it.
Types of Holter and Event Monitors
Holter Monitors
Holter monitors are sometimes called continuous
EKGs
(electrocardiograms). This is because Holter monitors record the heart rhythm
continuously for 24 to 48 hours.
A Holter monitor is about the size of a large deck
of cards. You can clip it to a belt or carry it in a pocket. Wires connect the
device to sensors (called electrodes) that are stuck to your chest using sticky
patches. These sensors pick up your heart's electrical signals, and the monitor
records your heart's rhythm.
Wireless Holter Monitors
Wireless Holter monitors have a longer recording
time than standard Holter monitors. The wireless version records your heart's
electrical activity for a preset amount of time.
These monitors are called wireless because they use
a cell phone to send the data to your doctor's office. This happens
automatically at certain times. These monitors still have wires that connect
the device to the sensors stuck to your chest.
You can use a wireless Holter monitor for days or
even weeks until signs or symptoms of a heart rhythm problem occur. These
monitors usually are used to detect heart rhythm problems that don't occur
often.
Although wireless Holter monitors work for longer
periods, they have a down side. You must remember to write down the time of
symptoms, so your doctor can match it to the heart rhythm recording. Also, the
batteries in the wireless monitor must be changed every 1 to 2 days.
Event Monitors
Event monitors are similar to Holter monitors. You
wear one while you do your normal daily activities. Most event monitors have
wires that connect the device to sensors that are stuck to your chest using
sticky patches.
Unlike Holter monitors though, event monitors don't
continuously record the heart's electrical activity. They only record when
symptoms occur. For many event monitors, you need to start the monitor when you
feel symptoms.
Event monitors tend to be smaller than Holter
monitors because they don't need to store as much data.
Different types of event monitors work in slightly
different ways. Your doctor will explain how to use the monitor before you
start wearing it.
Postevent Recorders
Postevent recorders are among the smallest event
monitors. You can wear a postevent recorder like a wristwatch or carry it in
your pocket. The pocket version is about the size of a thick credit card. These
recorders don't have wires that connect the device to chest sensors.
When you feel a symptom, you start the recorder. A
postevent recorder only records what happens after you start it. It may miss a
heart rhythm problem that occurs before and during the onset of symptoms. Also,
it may be hard to start the monitor when a symptom is in progress.
In some cases, this missing data would have helped
your doctor diagnose the heart rhythm problem.
Presymptom Memory Loop Recorders
Presymptom memory loop recorders are the size of a
small cell phone. They're also called continuous loop event recorders.
You can clip this event monitor to your belt or
carry it in your pocket. Wires connect the device to sensors on your chest.
These recorders are always recording and erasing
data. When you feel a symptom, you push a button on the device. The normal
erase process stops. The recording will show a few minutes of the data from
before, during, and after the symptom.
In some cases, this makes it possible for your
doctor to see very brief changes in your heart's rhythm.
Autodetect Recorders
Autodetect recorders are about the size of the palm
of your hand. Wires connect the device to sensors on your chest.
You don't need to start an autodetect recorder
during symptoms. These recorders detect abnormal heart rhythms and
automatically record and send the data to your doctor's office.
Implantable Loop Recorders
You may need an implantable loop recorder if other
event monitors can't provide enough data. Implantable loop recorders are about
the size of a pack of gum. This type of event monitor is inserted under the
skin on your chest. No wires or chest sensors are used.
The device records either when you activate it or
automatically when symptoms occur. It depends on how your doctor programs it.
Devices may differ, so your doctor will tell you how to use it. In some cases,
a special card is held close to the recorder to start it.
Other Names for Holter and Event Monitors
- Ambulatory EKG (electrocardiogram).
- Continuous EKG.
- EKG event monitors.
- Episodic monitors.
- Mobile cardiac outpatient telemetry systems. This
is another name for autodetect recorders.
- Thirty-day event recorders.
- Transtelephonic event monitors. These are
monitors that require the patient to send the collected data to a doctor's
office. This is done using a telephone.
Who Needs a Holter or Event Monitor?
You may need a Holter or event monitor if your
doctor suspects you have an
arrhythmia.
This is a problem with the speed or rhythm of your heartbeat. Holter or event
monitors are most often used to detect arrhythmias in people who have:
- Fainted or sometimes feel dizzy. A monitor may be
used if causes other than a heart rhythm problem have been ruled out.
- Palpitations (pal-pi-TA-shuns) that recur with no
known cause. Palpitations are the feeling that your heart is pounding, racing,
fluttering, or beating unevenly.
People who are being treated for a heart rhythm
problem also may need to use a Holter or event monitor. These monitors can show
how treatment is working.
In some people, heart rhythm problems only occur
during certain events, such as sleep or physical exertion. Holter and event
monitors record the heart rhythm while a person does his or her normal daily
routine. This allows the doctor to see how the heart responds to different
daily activities, which helps diagnose the problem.
Holter and event monitors also are used for elderly
people who may have trouble getting to and from clinics.
What To Expect Before Using a Holter or Event
Monitor
Your doctor will do a physical exam before giving
you a Holter or event monitor. He or she will:
- Check your pulse to find out how fast your heart
is beating and measure your blood pressure.
- Listen to the rate and rhythm of your heart.
- Check for swelling in your legs or feet. This
could be a sign of an enlarged heart or
heart
failure, which may cause
arrhythmias
(problems with the speed or rhythm of the heartbeat).
- Look for signs of other diseases (such as thyroid
disease) that could be causing heart rhythm problems.
You may have an
EKG
(electrocardiogram) test before your doctor sends you home with a Holter or
event monitor. An EKG detects and records the electrical activity of the heart
for a few seconds. It shows how fast the heart is beating and its rhythm
(steady or irregular). It also records the strength and timing of electrical
signals as they pass through each part of the heart.
A standard EKG wont detect heart rhythm
problems that dont happen during the test. For this reason, your doctor
may give you a Holter or event monitor. These monitors are portable. You can
wear one while doing your normal daily activities. This increases the chance of
recording symptoms that only occur once in a while.
Your doctor will explain how to wear and use the
Holter or event monitor. Usually, you will leave the office wearing it.
Each type of monitor is slightly different, but most
have sensors (called electrodes) that are attached to the skin on your chest
with sticky patches. Its important that the sensors have good contact
with your skin. Poor contact can result in poor results.
Oil, too much sweat, and hair can keep the patches
from sticking to your skin. You may need to shave the area on your chest where
your doctor will attach each patch. You will need to clean the area with a
special prep pad that the doctor will provide.
You may need to use a small amount of special paste
or gel to make the patches stick to your skin better. Some patches come with
paste or gel on them.
What To Expect When Using a Holter or Event
Monitor
Your experience while using a Holter or event
monitor depends on the type of monitor you have. However, most monitors have
some factors in common.
Recording the Hearts Electrical Activity
All monitors record the hearts electrical
activity. So, its important to maintain a clear signal between the
sensors (electrodes) and the recording device.
In most cases, the sensors are attached to your
chest with sticky patches. Wires connect the sensors to the monitor. You
usually can clip the monitor to your belt or carry it in your pocket.
(Postevent and implantable loop recorders dont have chest sensors.)
Holter or Event Monitor
![Illustration showing how a Holter or event monitor attaches to a patient.](https://webarchive.library.unt.edu/eot2008/20090508165623im_/http://www.nhlbi.nih.gov/health/dci/images/holter_monitor.jpg)
Figure A shows how a Holter or event
monitor attaches to a patient. In this example, the monitor is clipped to the
patients belt and electrodes are attached to his chest. Figure B shows an
electrocardiogram strip, which maps the data from the Holter or event
monitor.
A good stick between the patches and your skin helps
provide a clear signal. Poor contact leads to a poor recording, which is hard
for your doctor to read.
Oil, too much sweat, and hair can keep the patches
from sticking to your skin. You may need to shave the area where your doctor
will attach each patch. You will need to clean the area with a special prep pad
that your doctor provides.
You may need to use a small amount of special paste
or gel to make the patches stick to your skin better. Some patches come with
paste or gel on them.
Too much movement can pull the patches away from the
skin or create noise on the rhythm strip. A rhythm strip is a graph
showing the pattern of the heartbeat. Noise looks like a lot of jagged lines
and makes it hard for the doctor to see the real rhythm of the heart.
When you have a symptom, stop what youre
doing. This way you can be sure that the recording shows the hearts
activity rather than your movement.
Your doctor will tell you whether you need to adjust
your activity level during the testing period. If you exercise, choose a cool
location to avoid sweating too much. This will help the patches stay
sticky.
Other everyday items also can disrupt the signal
between the sensors and the monitor. These items include magnets, metal
detectors, microwave ovens, and electric blankets, toothbrushes, and razors.
Avoid using these items. Also avoid areas with high voltage.
Cell phones and iPods may interfere with the signal
if theyre too close to the monitor. When using any electronic device, try
to keep it at least 6 inches away from the monitor.
Keeping a Diary
When using a Holter or event monitor, you need to
keep a diary of your symptoms and activities. Write down when symptoms occur,
what they are, and what you were doing at the time.
The most common symptoms of heart rhythm problems
include:
- Palpitations. This is the feeling that your heart
is pounding, racing, fluttering, or beating unevenly.
- Fainting or feeling dizzy.
Its important to note the time symptoms occur,
because your doctor matches the data with the information in your diary. This
allows your doctor to see whether certain activities trigger changes in your
heart rate and rhythm.
You also should include details in your diary about
when you take any medicine or if you feel stress at certain times during the
test.
What To Expect With Specific Monitors
Holter Monitor
The Holter monitor is about the size of a large deck
of cards. You wear it for 24 to 48 hours. When the test is complete, you return
the device to your doctors office. The results are stored on the device.
You cant get the monitor wet, so you
wont be able to bathe or shower. You can take a sponge bath if
needed.
The recording period for a standard Holter monitor
may be too short to capture a heart rhythm problem. If this is the case, you
may need a wireless Holter monitor.
Wireless Holter Monitors
Wireless Holter monitors can record for a longer
time than standard Holter monitors. A wireless monitor records for a preset
amount of time. It then automatically sends data from the monitor to your
doctors office.
These monitors are called wireless because they use
a cell phone to send the data to your doctors office. They still have
wires that connect the device to the sensors stuck to your chest.
You can use a wireless Holter monitor for days or
even weeks until signs or symptoms of a heart rhythm problem occur.
The batteries in the wireless monitor must be
changed every 1 to 2 days. You will need to detach the sensors to shower or
bathe and then reattach them.
Event Monitors
Event monitors are slightly smaller than Holter
monitors. Event monitors record heart rhythm problems when you activate them.
They can be worn for weeks or until symptoms occur.
Most event monitors are worn like Holter
monitorsclipped to a belt or carried in a pocket. When you have symptoms,
you simply push a button to start recording.
Postevent Recorders
Postevent recorders may be worn like a wristwatch or
carried in a pocket. The pocket version is about the size of a thick credit
card. These recorders dont have wires that connect the device to chest
sensors.
To start the recorder when you feel a symptom, you
hold it to your chest. To start the wristwatch version, you touch a button on
the side of the watch.
You send the stored data to your doctors
office using a telephone. Your doctor will explain how to use the monitor
before you leave the office.
Autodetect Recorders
Autodetect recorders are about the size of the palm
of your hand. Wires connect the device to sensors on your chest.
You dont need to start an autodetect recorder.
This type of monitor automatically starts recording when it detects an abnormal
heart rhythm. It then sends the data to your doctors office.
Implantable Loop Recorders
Implantable loop recorders are about the size of a
pack of gum. This type of event monitor is inserted under the skin on your
chest. No chest sensors are used.
The device records either when you activate it or
automatically when symptoms occur. It depends on how your doctor programs it.
Devices may differ, so your doctor will tell you how to use it. In some cases,
a special card is held close to the recorder to start it.
What To Expect After Using a Holter or Event
Monitor
After youre finished using a Holter or event
monitor, you return it to your doctors office or the place you got it
from.
If you were using an implantable loop recorder, you
will need to have it removed. Your doctor will discuss the procedure with
you.
Your doctor will tell you when to expect the
results. Once your doctor has reviewed the recordings, he or she will discuss
the results with you.
What Does a Holter or Event Monitor Show?
A Holter or event monitor may show whats
causing symptoms of an
arrhythmia.
This is problem with the speed or rhythm of the heartbeat.
Holter and event monitors also can show whether a
heart rhythm problem is harmless or whether it needs treatment. Treatment is
needed if the problem causes serious symptoms or increases your chance for
complications.
Serious symptoms may include dizziness, chest pain,
and fainting. Complications may include
heart
failure, stroke, or
sudden
cardiac arrest.
If the symptoms of your heart rhythm problem occur
often, a Holter or event monitor has a good chance of capturing them. You may
not have symptoms while using a monitor. Even so, your doctor may learn more
about your heart rhythm from the test results.
Sometimes, these monitors cant help doctors
diagnose heart rhythm problems. If this happens, talk to your doctor about
other steps you can take.
One option may be to try a different type of
monitor. The wireless Holter monitor and the implantable loop recorder have
longer recording periods. This may allow the monitor to get the data that your
doctor needs to make a diagnosis.
What Are the Risks From Using a Holter or Event
Monitor?
The sticky patches used to attach the sensors
(electrodes) to your chest have a small risk of skin irritation. You also may
have an allergic reaction the paste or gel thats sometimes used to attach
the patches. The irritation will go away once the patches are removed.
If youre using an implantable loop recorder,
you may get an infection or have pain where the device is placed under the
skin. You may be given medicine to treat these complications.
Key Points
- Holter and event monitors are medical devices
that record the hearts electrical activity.
- Doctors most often use these monitors to diagnose
arrhythmias.
These are problems with the speed or rhythm of the heartbeat. During an
arrhythmia, the heart can beat too fast, too slow, or irregularly.
- Holter and event monitors also are used to detect
silent myocardial ischemia. In this condition, not enough oxygen-rich blood
reaches the heart muscle. Silent means that no symptoms occur.
- These monitors also can check whether treatments
for arrhythmia and silent myocardial ischemia are working.
- Holter and event monitors are similar to an
EKG
(electrocardiogram). An EKG is a simple test that detects and records the
hearts electrical activity. Its the most common test for diagnosing
a heart rhythm problem. However, a standard EKG only records the heartbeat for
a few seconds.
- Holter and event monitors are small, portable
devices. You can wear one while you do your normal daily activities. This
allows them to record your heart for a longer time than an EKG. Holter and
event monitors are used to detect heart rhythm problems that may not occur all
the time.
- You may need a Holter or event monitor if your
doctor suspects you have a heart rhythm problem. Holter or event monitors are
most often used to detect these problems in people who have:
- Fainted or sometimes feel dizzy. A monitor
may be used if causes other than a heart rhythm problem have been ruled
out.
- Palpitations that recur with no known cause.
Palpitations are the feeling that your heart is pounding, racing, fluttering,
or beating unevenly.
- People who are being treated for a heart rhythm
problem also may need to use a Holter or event monitor. These monitors can show
how treatment is working.
- Your doctor will do a physical exam before giving
you a Holter or event monitor. There are many types of Holter and event
monitors. Your doctor will help decide which type is right for you.
- Your experience while using a Holter or event
monitor depends on the type of monitor you have. Your doctor will tell you how
to use your monitor.
- After youre finished using a Holter or
event monitor, you return it to your doctors office or the place you got
it from. Your doctor will tell you when to expect the results.
- A Holter or event monitor may show whats
causing symptoms of a heart rhythm problem. Holter and event monitors also can
show whether a heart rhythm problem is harmless or whether it needs treatment.
- Treatment is needed if the problem causes serious
symptoms or increases your chance for complications.
- Holter and event monitors have few risks.
Links to Other Information About Holter and Event
Monitors
NHLBI Resources
Non-NHLBI Resources
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