Ambulatory Cardiac Monitoring
all information

Ambulatory Cardiac Monitoring

(Holter Monitoring; Ambulatory Electrocardiography [EKG])

En Español (Spanish Version)


Ambulatory cardiac monitoring is a way to monitor and record the electrical activity of your heart as you go about your daily activities. It is used to determine whether the heart may be beating too slow or too fast and to detect any abnormalities in heart rhythm.

Your heart must beat roughly every second of your life to pump blood to your body. If it falters (absence of a heart beat for a few seconds would not be fatal or serious ), the consequences can be serious or even fatal. Sudden death can be due to either the heart suddenly beating too slow or too fast.

How Your Heartbeat Is Regulated

Your heartbeat is regulated by electrical impulses. There are many ways in which these impulses can go astray. Some are of little consequence; others are lethal. Some are continuous and can easily be detected by a few minutes of electrocardiographic monitoring. Others occur only occasionally and are likely to be missed during the brief time an EKG is running, particularly if they occur only when you are doing something special rather than lying on the examining table or walking on a treadmill. Ambulatory cardiac monitoring records your heart’s electrical activity for long periods of time to detect the occasional abnormality.

Heartbeat on EKG Monitor

Nucleus image

© 2008 Nucleus Medical Art, Inc.

Types of Ambulatory Cardiac Monitoring

There are four separate types of ambulatory cardiac monitoring. Most of the devices are roughly the size of a pager or cell phone. The choice will depend upon the symptoms you are having, their frequency, and your doctor’s impression of what is happening.

  • Holter monitoring—A small device will be strapped to you. Wires from the device will be attached to electrodes (usually five) affixed to your chest. You will be instructed to keep a diary of your activities for the next 24 hours, and then return the device and your diary for analysis. Some devices have an event button that you will push to record each time you have symptoms.
  • Looping monitor—This device records several minutes at a time, then starts over, using one of several different types of electrodes: a wrist band, a finger attachment, or a chest plate. You will be instructed to push a button during or after an event to preserve the recording. For long periods of time, there is even an implantable version that is surgically installed under your skin.
  • Event recorder—You activate this device when you have symptoms. The device can be a wrist band with an activation button or a pager-sized device you press onto your chest. Some of these are continuously connected to 24-hour-a-day central bases that can immediately detect and respond to the event when you activate the signal.
  • CardioNet (mobile cardiac outpatient telemetry)—A special proprietary service monitors your heartbeat continuously and will respond immediately if it detects a serious event.

Parts of the Body Involved

Ambulatory cardiac monitoring is designed exclusively to recognize electrical disturbances in your heart. Most of the indications are for rhythm changes. It’s occasionally used to detect ischemia—interruption or reduction of blood supply that causes angina and heart attacks (“coronaries”).

Reasons for Procedure

There are three primary reasons to use ambulatory cardiac monitoring:

  • Fainting spells suspected of having a cardiac cause
  • Ischemia that causes no symptoms—usually done after a heart attack
  • Monitoring dangerous rhythm disturbances while selecting an effective treatment

Risk Factors for Complications During the Procedure

The procedure has no associated risks other than that of the suspected condition.

What to Expect

Prior to Procedure

You will first be evaluated by a physician, most likely a cardiologist. You will then have an EKG.



Description of the Procedure

If the device is to be attached to you, small areas of your chest may be shaved before the electrodes are attached. You will either learn to reattach them or be instructed not to bathe or remove them for the duration of the test. Certain environmental interferences should be avoided—magnets, metal detectors, high-voltage, radio frequency signalers, microwave ovens, electric blankets, electric toothbrushes, and razors.

After Procedure

You will return the device and your diary for analysis.

How Long Will It Take?

A typical interval is 24 hours. If your problem is less frequent than that, you may need to be monitored for a longer period of time, which often requires different devices.

Will It Hurt?

Other than when the electrodes are peeled off your skin, this procedure will not hurt.

Possible Complications


Average Hospital Stay


Postoperative Care

When your problem is diagnosed, your physician will proceed to identify treatment options. There are different types of arrhythmias and different treatment options.


The goal is to prevent palpitations, fainting spells, and sudden death.

Call Your Doctor If Any of the Following Occurs

You will be instructed what to do when anticipated symptoms occur during the test.


American Heart Association

National Library of Medicine


Heart and Stroke Foundation of Canada

Mount Sinai Hospital, Canada


Abbott AV. Diagnostic Approach to Palpitations. American Family Physician. 2005;71. Available at: . Accessed August 19, 2005.

ACC/AHA clinical competence statement on electrocardiography and ambulatory electrocardiography. American College of Cardiology website. Available at: . Accessed August 19, 2005.

Ambulatory monitors. Cleveland Clinic Heart Center website. Available at: . Accessed August 19, 2005.

Last reviewed November 2007 by J. Peter Oettgen, MD

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.

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