What is it?

A Holter monitor is a small device that records the electrical activity of your heart. You wear it while you do all your normal activities.

The monitor has wires that attach to small electrode pads. These pads are taped to your chest.

This kind of machine has many different names. It is sometimes called an ambulatory monitor, an ambulatory electrocardiogram, or an ambulatory ECG. It can also be called a 24-hour ECG or a cardiac event monitor.

Why is this test done?

You may have this test to find out if you have a problem with your heart. Many heart problems can only be noticed when you are doing something. They may happen when you exercise, eat, have sex, or sleep. Or they may happen when you have a bowel movement or you feel stressed. Your Holter monitor will record the way your heart beats during all of these activities.

Holter monitoring also will:

• Look for what may cause chest pain, dizziness, or fainting.
• Check to see if treatment for an irregular heartbeat is working.

How is the test done?

• Areas of your chest may be shaved and cleaned.
• The electrode pads are attached, like stickers, to your chest.
• Your doctor will show you how to wear or carry the monitor. For example, you might wear the monitor on a strap over your shoulder, hooked on a belt, or placed in a pocket. It does not weigh much.
• The monitor will record your heart's activity and save the information.
• Your doctor may give you extra instructions on how to use the monitor at home.

How is the monitor used?

• You need to record your activities and symptoms. Your monitor might have a button that you can push when you feel symptoms.
• You will also keep a diary. You will write down the time your symptoms started. And you will write down what type of activity you were doing.
• You can use the clock on the monitor to help you keep track of the time your symptoms started.
• Your doctor will tell you if you need to stay away from certain electric devices while you wear the monitor. Many household and office electronics do not affect your monitor.
• Be sure to follow your doctor's instructions for bathing, exercise, and other daily activities.

How does the test feel?

The pads may make your skin itch a little. And your skin may look or feel irritated after the pads are removed.

How long will you wear the monitor?

Most people wear the monitor for 24 to 48 hours. Some people wear it longer than 48 hours.

What happens after the test?

• Your doctor will give you extra instructions on what to do when the test is done.
• You may return to the doctor's office or hospital to have the pads removed. Or you may be able to take them off yourself by following the instructions.
• Your doctor will tell you how to return the monitor.
• You can go back to your usual activities right away.