24-Hour Holter Monitoring

Written by Erica Roth | Published on August 15, 2012
Medically Reviewed by Brenda B. Spriggs, MD, MPH, FACP

What is a Holter Monitor?

A Holter monitor is a small of portable, battery-powered medical device that measures the heart’s activity such as rate and rhythm). This testing is ordered when your doctor needs more information about the functioning of your heart than a routine electrocardiogram (EKG) can give him or her.

Holter monitoring (24h) refers to a 24-hour, continuous test to record your heart rate and rhythm. This device has electrodes and electrical leads exactly like a regular electrocardiogram. A patient wears the Holter monitor for 12 to 48 hours as they go about their normal daily routines.

Holter monitor testing is also sometimes called ambulatory electrocardiography.

Reasons Your Doctor May Order Holter Monitoring

An electrocardiogram is a medical test that is typically ordered to measure heart rate and rhythm and to look for other abnormalities that may affect normal heart function. However, patients may experience heart rhythm irregularities that do not show up at the time the electrocardiogram is done. In these cases, if an irregular heartbeat (arrhythmia) is suspected, your doctor may order a Holter monitor test.

The Holter monitor lets your doctor see how your heart functions on a long-term basis. The recordings made by the monitor help your doctor determine if your heart is getting enough oxygen or if the electrical impulses in the heart are delayed.

How it Works

The Holter monitor is small, slightly larger than a deck of playing cards. Several leads, or wires, are attached to the monitor. The leads connect to electrodes that are placed on the skin of your chest with a glue-like gel. The metal electrodes conduct your heart’s activity through the wires into the Holter monitor.

A small pouch holds the monitor itself, which you wear around your neck. It’s important to keep the monitor close to your body during the testing period to make sure the readings are accurate. Your doctor will show you how to re-attach electrodes if they become loose or fall off during the testing period.

You are encouraged to participate in your normal activities during the Holter 24-hour test. You will be directed to record your activities in a notebook. This helps your doctor determine if changes in heart activity are related to your behaviors and movements.

Holter monitor testing is painless. However, be sure to record any chest pain, rapid heartbeat, or other cardiac symptoms you experience during the testing period.

Accuracy of Testing

Keep the Holter monitor dry to ensure the equipment functions properly. Take a bath or shower before your appointment to have the monitor fitted. Avoid activities that might lead to the monitor getting wet.

Keeping the Holter monitor dry and avoiding activities that might lead to the monitor getting wet will ensure proper functioning of the equipment.

Magnetic and electrical fields may interfere with the function of the Holter monitor. Avoid areas of high voltage while wearing the monitor. The National Institutes of Health (NIH) cautions patients not to use electric blankets or to go through a metal detector during the testing period.

Understanding the Results

After the recommended testing time frame has passed, you will return to your healthcare provider to have the Holter monitor removed. Your doctor will read your activity journal and the results of the monitor. Depending on the results of the test, you may need to undergo further testing before a diagnosis is made.

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