Holter monitoring is a painless way to record your heart's electrical activity away from your doctor's office. It is a small, battery-operated, portable electrocardiogram (ECG) machine. The monitor may have a wire or wires, or it may be a patch without wires. Holter monitoring records your heartbeat for at least 24 hours, and some monitors may record your heartbeat up to 14 days. Your doctor then reviews the information at a later time. You can get your Holter monitor at a hospital, at a test center, at a doctor's office, or in the mail.

The monitor is used to record any problems with your heartbeat. It can show racing heartbeats, slow heartbeats, skipping heartbeats, fluttering heartbeats (palpitations), and fainting. All of these symptoms may be caused by an abnormal heartbeat (arrhythmia). Holter monitors also provide information about your average heart rate throughout the day.

When you get a Holter monitor, your doctor puts small, sticky pads (electrodes) on your chest. These connect to the monitor by wires or leads. The monitor attaches to a belt or shoulder strap. Newer Holter monitors don't require wires or leads. They're placed directly over the heart with a sticky patch. You need to keep the device on for at least 24 to 48 hours or as advised by your doctor. You also need to fill out a diary keeping track of any symptoms you may have during the monitoring period. Your doctor will tell you how to do this.

While wearing the monitor, follow these tips:

• Try to sleep on your back.
• You may be able to shower with a patch monitor, but not a wired monitor.
• Don't take a bath, swim, or use a hot tub. Don't put the monitor underwater.
• Follow your normal routine. Go to work and exercise as usual. It's important to record your heartbeat during your normal activities.
• If an electrode or patch falls off, try to stick it back on or replace it as instructed.
• If the monitor makes noise, or if you have any trouble with the monitor, call the phone number for device support provided with your monitor. You may also contact your doctor's office if needed.
• When the monitoring period is over, you will return to your doctor's office or an electrocardiogram center. Sometimes your monitor may be returned by mail. Make sure you know where to return your device. Once your doctor receives the information from your monitor, it will be reviewed.
• It may take about 1 week for the information to be looked at. Ask your doctor if you should have a follow-up appointment or how you will get the results from your test.

While wearing the monitor, stay away from things that may affect the recording, such as:

• Electric blankets.
• Magnets.
• Metal detectors.
• High-voltage areas, such as power lines.

And don't use machines with large motors or that cause vibrations. These can also affect the recording.

Keep a diary of things you do during the day. This is important. It could help you match your symptoms to times when your heart is beating abnormally. Your diary may be a paper form, an online website, or a phone app. Your doctor's office will tell you which one to use.

• Note the day and time for each entry you make.
• Note all activities. This includes when you take medicines, drive, take a nap, walk, sit down, exercise, or feel stress.
• Note any symptoms you feel. These might be fluttering heartbeats or skipped beats, chest pain, back pain, nausea, or other symptoms. Also write down what was going on around you when the symptoms occurred. Write down any symptoms, even if you are not sure they are important.