Holter monitor


Holter monitor

A Holter monitor is a small, wearable device that keeps track of your heart rhythm. Your doctor may want you to wear a Holter monitor for one to two days. During that time, the device records all of your heartbeats.

A Holter monitor test may be done if a traditional electrocardiogram (ECG) doesn't give your doctor enough information about your heart's condition.

Your doctor uses information captured on the Holter monitor to figure out if you have a heart rhythm problem. If standard Holter monitoring doesn't capture your irregular heartbeat, your doctor may suggest a longer-term monitor, which can record your heartbeat over several weeks.

Some personal devices, such as smartwatches, offer electrocardiogram monitoring. Ask your doctor if this is an option for you.

Why it's done

Your doctor may recommend that you wear a Holter monitor for a day or so if you have signs and symptoms of an irregular heart rhythm (arrhythmia) or unexplained fainting.

Before you get a Holter monitor, you'll have an electrocardiogram (ECG). An ECG is a quick and painless test that uses sensors (electrodes) taped to your chest to check your heart's rhythm.

However, sometimes an ECG doesn't detect any changes in your heart rhythm because you're hooked up to the machine for only a short time. A Holter monitor may be able to spot occasionally abnormal heart rhythms that an ECG missed.

A Holter monitor test may also be done if you have a heart condition that increases your risk of an abnormal heart rhythm.


There are no significant risks involved in wearing a Holter monitor other than possible discomfort or skin irritation where the electrodes were placed.

However, the Holter monitor can't get wet, or it will be damaged. Don't swim or bathe for the entire time you're wearing your Holter monitor. However, if you have a wireless Holter monitor, you'll be shown how to disconnect and reconnect the sensors and the monitor so that you can shower or bathe.

Holter monitors aren't usually affected by other electrical appliances. But some devices can interrupt the signal from the electrodes to the Holter monitor. If you have a Holter monitor, you should avoid the following:

  • Electric blankets
  • Electric razors and toothbrushes
  • Magnets
  • Metal detectors
  • Microwave ovens

Also, keep your cellphones and portable music players at least 6 inches from the Holter monitor for the same reason.

How you prepare

If your doctor recommends a Holter monitor, you'll have the device placed during a scheduled appointment. Unless your doctor tells you otherwise, plan to bathe before this appointment. Most monitors can't be removed and must be kept dry once monitoring begins.

A technician will place sensors (electrodes) on your chest. These electrodes detect your heartbeat and are about the size of a silver dollar. For men, a small amount of hair may be shaved to make sure the electrodes stick.

The technician will then connect the electrodes to a recording device with several wires and will instruct you on how to properly wear the recording device so it works properly. The Holter monitor recording device is about the size of a deck of cards.

Once your monitor is fitted and you've received instructions on how to wear it, you can leave your doctor's office and resume your normal activities.

What you can expect


Holter monitoring is painless and noninvasive. You can hide the electrodes and wires under your clothes, and you can wear the recording device on your belt or attached to a strap. Once your monitoring begins, don't take the Holter monitor off — you must wear it at all times, even while you sleep.

While you wear a Holter monitor, you can carry out your usual daily activities. You'll usually be given a form to help you record your activities and any symptoms. It's particularly important to note if and when you have any of the following symptoms:

  • Any pounding, fluttering or skipped heartbeats
  • Shortness of breath
  • Chest pain
  • Lightheadedness

Write down what activities you do and exactly what time you do them.

Your doctor will tell you how long you'll need to wear the monitor. It may vary from 24 to 48 hours, depending on what condition your doctor thinks you have or how frequently you have symptoms of a heart problem. A wireless Holter monitor can work for weeks.


Once your monitoring period is over, you'll return the device to your doctor's office. If you were asked to keep a record of symptoms that you had while wearing the device, your doctor can compare data from the Holter monitor recorder with your notes. This can help your doctor diagnose your condition.


After your doctor has looked at the results of the Holter monitor recorder, he or she will talk to you about your results. The information from the Holter monitor can tell your doctor if you have a heart condition and if heart medicines you currently take are or aren't working.

If you didn't have any irregular heart rhythms while you wore the monitor, your doctor may not be able to diagnose your condition. Your doctor may recommend a wireless Holter monitor or an event recorder, both of which can be worn longer than a standard Holter monitor. Event recorders are similar to Holter monitors and generally require you to push a button when you feel symptoms. There are several different types of event recorders.

Content Last Updated: May 5, 2021

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