Ambulatory electrocardiography

Alternative names
Holter monitor (24h); Electrocardiography - ambulatory


Holter monitoring provides a continuous recording of heart rhythm during normal activity. The monitor is usually worn for 24 hours to obtain a recording of a complete day.

How the test is performed

Electrodes (small conducting patches) are placed on your chest and attached to a small recording monitor that you can carry in a pocket or in a small pouch worn around your neck. The monitor is battery operated.

Your heart electrical activity is recorded (much like the recording of an ECG), usually for a 24-hour period while you keep a diary of your activities. The recording is then analyzed, a report of the heart’s activity is tabulated, and irregular heart activity is correlated with your activity at the time.

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

How to prepare for the test

There is no special preparation for the test. The recording monitor will be started by the health care provider, and you will be given instructions on how to replace electrodes should they become loosened. Instructions will also be given on how to record activity for the diary.
Tell your doctor if you are allergic to any tape or other adhesives. 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

There is no discomfort associated with the test. Hair may need to be shaved from the chest for electrode placement. You must keep the monitor close to the body, either in a pocket or in a pouch worn around the shoulder or neck.

Continue normal activities while wearing the monitor.

Why the test is performed

Holter monitoring is used to determine how the heart responds to normal activity. Other times Holter monitoring is used include the following:

  • When given cardiac medication  
  • After a heart attack  
  • To diagnose an abnormal or dangerous heart rhythm Normal Values Normal variations in heart rate occur with activities. No significant alterations in the rhythm or ST elevations occur. What abnormal results mean Abnormal results may include various arrhythmias. ST segment changes (alterations in the wave form of the electrical conduction pattern of the heart) may indicate that the heart is not receiving enough oxygen and may also correlate with chest pain. Additional conditions under which the test may be performed include the following:
    • Atrial fibrillation/flutter  
    • Multifocal atrial tachycardia  
    • Paroxysmal supraventricular tachycardia  
    • Palpitations  
    • Fainting

    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 to permit accurate recording of the heart’s activity.

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

    Johns Hopkins patient information

    Last revised: December 5, 2012
    by David A. Scott, M.D.

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