Alternative names   

Ambulatory electrocardiography; Electrocardiography - ambulatory

Definition   

A Holter monitor is a machine that continuously records the heart's rhythm for 24 to 48 hours. The monitor is usually worn for 24 hours during normal activity.

How the test is performed   

Electrodes (small conducting patches) are stuck onto your chest and attached to a small recording monitor. You carry the Holter monitor in a pocket or in a small pouch worn around your neck or waist. The monitor is battery operated.

While you wear the monitor, it records your heart's electrical activity. You should keep a diary of what activities you do while wearing the monitor. After 24-hours, you return the monitor to your doctor's office. The doctor will look at the records and see if there have been any irregular heart rhythms.

It is very important that you accurately record your symptoms and activities so that the doctor can match them with your Holter monitor findings.

How to prepare for the test   

There is no special preparation for the test. Your doctor will start the monitor. You'll be told how to replace the electrodes, should they fall off or become loose.

Tell your doctor if you are allergic to any tape or other adhesives. Make sure you shower or bathe before you start the test. You will not be able to do so while you are wearing a Holter monitor.

How the test will feel   

This is a painless test. However, some people may need to have their chest shaved so the electrodes can stick.

You must keep the monitor close to your body. This may make sleeping difficult for some people.

You should continue your normal activities while wearing the monitor.

Why the test is performed   

Holter monitoring is used to determine how the heart responds to normal activity. The monitor may also be used:

• When starting a new heart medicine
• After a heart attack
• To diagnose heart rhythm problems

It may be used to diagnose:

• Atrial fibrillation/flutter
• Multifocal atrial tachycardia
• Paroxysmal supraventricular tachycardia
• Palpitations
• Reasons for fainting

Normal Values   

Normal variations in heart rate occur with activities. A normal result is no significant changes in heart rhythms or pattern.

What abnormal results mean   

Abnormal results may include various arrhythmias. Changes in the normal pattern of waves formed by the heart's electrical signals may mean that the heart is not getting enough oxygen.

What the risks are   

There are no risks associated with the test. However, you should be sure not to let the monitor get wet.

Special considerations   

Electrodes must be firmly attached to the chest so the machine gets an accurate recording of the heart's activity.

Avoid magnets, metal detectors, electric blankets, and high-voltage areas while wearing the device.

Update Date: 7/17/2006

Updated by: Glenn Gandelman, MD, MPH, Assistant Clinical Professor of Medicine, New York Medical College, Valhalla, NY. Review provided by VeriMed Healthcare Network.