Ambulatory Electrocardiogram

Cardiac Event Monitoring, Electrocardiography, Ambulatory, Holter Monitoring

How It Is Done

Continuous recorders

For this test, you wear a lightweight, battery-operated tape recorder (monitor) on a strap over your shoulder or around your waist. The recorder is connected by wires to small metal discs (electrodes) taped to your chest. The electrodes detect the electrical signals from your heart. A clock is connected to the recorder so you can note what time it is when you have any symptoms.

You will be fitted with the recorder and electrodes by a technician in a doctor's office or hospital room.

• Several areas on your chest may be shaved and cleaned, and then a small amount of electrode paste or gel will be applied to those areas.
• The electrode pads will then be attached to the skin of your chest, with thin wires connecting the electrodes to the monitor.
• You may be hooked up briefly to a standard EKG machine to ensure that the electrodes are working properly.

While wearing the continuous recorder, you will also be asked to keep a diary of all your activities and symptoms, including the type of activity you were doing and the time your symptoms started. In the diary, write down the exact times when you exercise, climb stairs, eat, urinate, have a bowel movement, have sex, sleep, get emotionally upset, take medicine, or perform other activities. If you have any symptoms of heart problems, such as dizziness, fainting, chest pain, or palpitations, push the event-marker button on the recorder to mark it and write down the exact time and how long the symptom lasts. For example, you might write: "12:30 p.m. Ate lunch. 1:00 p.m. Argument with boss, had chest tightness for several minutes."

When you sleep, try to stay on your back with the recorder carefully positioned at your side so that the electrodes are not pulled off. If one of the electrodes or lead wires comes loose, a light on the monitor will flash. Press on the center of each electrode to see if you can restore the contact. Call your doctor if one of the electrodes comes off and you can't get it to stay on.

While you are wearing a monitor, try to stay away from magnets, metal detectors, high-voltage areas, garage door openers, microwave ovens, and electric blankets. Do not use an electric toothbrush or shaver. Signals from these types of electronic equipment can sometimes interfere with the recording.

At the end of the recording period (usually 24 hours), you will return to the doctor's office or hospital to have the electrodes removed, or you may be able to remove the electrodes yourself. The recorded tape will be read by computer to provide information about your heart rate, the frequency of your heartbeats, and any irregularities.

After the monitoring period, your doctor will compare the timing of your activities and symptoms with the recorded heart pattern. The accuracy and usefulness of this test depend on how carefully you record your activities and symptoms and the times they occurred.

Intermittent recorders

The procedure for intermittent recording depends on the type of monitor used.

• Loop recorder. Electrodes will be attached to your chest in the same way as a continuous recorder, and you will start the recorder when you have symptoms of a heart problem. If you pass out, you should start the recorder as soon as you wake up. Also, be sure a friend or family member knows how to start the recorder if you pass out.
• Event monitor. You will carry the small recording device where you can reach it quickly, such as in your pocket or purse. When you have symptoms of a heart problem, press the small metal discs on the back of the monitor (electrodes) against your chest.

You may be instructed to call your doctor, clinic, or hospital while you are having symptoms or soon after you record your heart rhythm so that the information on the monitor can be analyzed right away.

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Author:	Robin Parks, MS	Last Updated: December 24, 2007
Medical Review:	E. Gregory Thompson, MD - Internal Medicine Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology
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