A Holter monitor is a medical device that records the heartbeat and checks for unusual signs. Doctors may order 24-hour Holter monitoring if they need more information about a person's heart, after having used standard electrocardiography.

In this article, learn what to expect when using a Holter monitor and what the results mean.

24-hour Holter monitoring device in a man's chestShare on Pinterest
A Holter monitoring device measures a person's heartbeat for 24 hours.

A small, battery-powered electrocardiogram (ECG) device is attached to the body. This monitor a person's heart as they go about their daily activities.

When people report symptoms of heart problems, doctors often use ECGs to help diagnose the issue. A standard ECG shows a snapshot of the heart's overall electrical activity. If a snapshot is not sufficient, a doctor may request 24-hour Holter monitoring.

A Holter monitor attaches to the body in much the same way as a standard ECG. The small device has thin electrical cords with electrodes that are attached to areas of the chest.

The doctor may order Holter monitoring for 12, 24, or 48 hours, depending on the symptoms and how often they occur.

A doctor may ask for Holter monitoring if a person has symptoms such as:

  • a fast or slow heartbeat
  • dizziness
  • weakness or fatigue
  • feeling out of breath
  • chest pain
  • a fluttering sensation in the heart
  • an uneven heartbeat
  • the feeling of skipping heartbeats
  • dizziness while using a pacemaker

Many issues that affect the heartbeat only appear sporadically throughout the day, and a person is unlikely to be in a doctor's office when the problems occur.

This is one advantage of continuous Holter monitoring. The monitor can record the issue whenever it happens, helping doctors to diagnose the underlying problem.

The Holter device can also help to monitor people with diagnosed heart conditions as they go about their daily lives. A person is usually more comfortable with this arrangement than with lengthy hospital stays.

In addition, a doctor may order 24-hour Holter monitoring to check a person's response to medications for heart problems.

Using a 24-hour Holter monitor is simple, though it may look complicated. The monitor is small enough to fit in the palm of a hand, and it is usually worn around the neck or on the waist.

Several electronic wires, called leads, connect the unit to the electrodes attached to the body.

A technician will attach the electrodes to the skin with an adhesive gel to hold them in place and ensure accurate readings. If there is hair in the area, the technician may need to shave it before securing the electrodes.

Metal in the electrodes picks up the heart's activity as electrical signals. The electrodes then transmit the signals to the monitor, which records them.

Electrodes can loosen or fall off, and it is essential to reattach them. The doctor will explain how to do this.

Share on Pinterest
People continue their daily activities as usual during 24-hour Holter monitoring.

The doctor will explain what to expect and how to use the particular type of monitor. The general tips below can help to prevent faulty readings and keep a person from having to repeat the test.

Refrain from showering, bathing, and swimming while wearing a Holter monitor. A person can use wet wipes or a washcloth and soap to clean areas such as the face, armpits, buttocks, and groin. However, it is important to avoid getting the monitor, leads, or electrodes wet.

Otherwise, most people are asked to go about their days as usual while doing the 24-hour Holter test. This includes doing any regular exercises unless they involve sweating profusely or getting the area with the device wet.

While doing the test, the person will go to school or work as usual. A doctor may also ask them to limit their alcohol or caffeine consumption.

A person should record their daily activities and any symptoms they feel. Noting down the time that chest pain strikes, for example, can help doctors decide where to look first when deciphering the results.

An individual should also record the following information about what was happening when symptoms appeared:

  • what they were doing
  • any foods they had just eaten
  • whether they had just had something to drink
  • stress levels
  • whether they were active or resting

It is also helpful to check whether electrodes are still attached throughout the day. A loose or detached electrode can make the reading inaccurate.

Avoid areas of high voltage while wearing the monitor, because magnetic or electric fields can make the reading less accurate. Avoid powerful magnets, such as those in MRI machines and metal detectors.

Some electronic devices can interfere with the function of a Holter monitor. A doctor may recommend avoiding things like electric toothbrushes, razors, microwaves, and cell phones while using the monitor.

The 24-hour Holter monitor test is non-invasive. It may be inconvenient, but the test poses no serious risks.

The only possible risk is some skin irritation where the electrodes attach to the body. Anyone with an allergy to glues or adhesives should notify their doctor. The technician may be able to use a different substance to attach the electrodes to the body.

After the testing period, a person returns to their doctor to have the monitor removed. Turn in any notes to the doctor for review.

The doctor will consider the monitor's readings and the person's notes when making a diagnosis.

The Holter monitor's readings may reveal an underlying heart condition, new symptoms, and potential triggers. It may also help to show problems caused by medication.

A person may have to wait for 1–2 weeks for results of the test.

Once a doctor diagnoses the underlying cause of the symptoms, they can start discussing treatment options.

If a person is already following a treatment plan, the doctor may recommend adjusting the dosage or changing the medication.

A doctor is sometimes unable to make a diagnosis after reviewing the readings from 24-hour Holter monitoring. A person may not have had symptoms that day, or the monitor may not have picked up irregular activity.

In these cases, the doctor will order additional tests. They may also recommend longer-term monitoring. Wireless Holter monitors and adhesive-patch ECGs can record the heart's activity over a more extended period.

Holter monitoring may be a mild inconvenience for 24 hours, but it can provide vital information about underlying heart conditions.