An ambulatory electrocardiogram (EKG or ECG) records the electrical activity of your heart while you do your usual activities. (Ambulatory means that you are able to walk.) Ambulatory monitors are referred to by several names, including ambulatory electrocardiogram, ambulatory EKG, Holter monitoring, 24-hour EKG, or cardiac event monitoring.
Many heart problems become noticeable only during activity, such as exercise, eating, sex, stress, bowel movements, or even sleeping. A continuous 24-hour recording is more likely to detect any abnormal heartbeats that occur during these activities.
Many people have irregular heartbeats (arrhythmias) from time to time. The importance of irregular heartbeats depends on the type of pattern they produce, how often they occur, how long they last, and whether they occur at the same time you have symptoms. Because arrhythmias can occur off and on, it may be hard to record an arrhythmia while you are in the doctor's office.
There are several different types of ambulatory monitors. Your doctor will choose the type that is most appropriate for you and is most likely to help diagnose your heart problem.
Why It Is Done
Ambulatory EKG monitoring is done to:
How To Prepare
Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.
Since an EKG is often used to monitor a preexisting heart condition, such as an irregular heartbeat (arrhythmia), make sure that your doctor has copies of any previous EKG results.
Take a shower or bath before the discs are put on. You will not be able to get the discs wet during the test. Wear a loose blouse or shirt. Do not wear jewelry or clothes with metal buttons or buckles, because these can interfere with the recording. Women should not wear an underwire bra for the same reason.
If your doctor asks you to keep a symptom and activity diary, be sure you have a method. In this diary, you will record activities and symptoms and the times they occurred. The accuracy and usefulness of your test depend on how carefully you keep this record.
If you are getting a monitor implanted under your skin, you will receive instructions on how to prepare for the procedure.
Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).
How It Is Done
Continuous recorders are the most common type of ambulatory electrocardiogram monitor. This type includes the Holter monitor.
A continuous recorder provides a 24- to 72-hour record of the electrical signals from your heart. A standard EKG monitors only 40 to 50 heartbeats during the brief period you are attached to the machine. A continuous recorder monitors about 100,000 heartbeats in 24 hours and is likely to find any heart problems that happen with activity.
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.
See a picture of a Holter monitor.
You will be fitted with the recorder and electrodes by a technician in a doctor's office or hospital room.
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 to 72 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. You will return the Holter monitor to your doctor's office or hospital. The recorded tape will be read by computer to provide information about your heart rate, the frequency of your heartbeats, and any irregularities.
Your doctor will also look at your records of activities and symptoms and times they occurred. Your doctor will compare the timing of your activities and symptoms with the recorded heart pattern.
Implantable continuous recorders
Another type of continuous recorder can be implanted under the skin of the chest. This recorder can be kept in your chest for more than a year to record the electrical signals from your heart.
Another kind of ambulatory EKG monitoring is the intermittent recorder, which is used when symptoms of an abnormal heart rhythm do not occur very often. An intermittent recorder can be used for a longer time than a continuous recorder. The information collected by an intermittent recorder can often be sent over the phone to a doctor's office, clinic, or hospital.
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.
The procedure for intermittent recording depends on the type of monitor used.
How It Feels
If you have electrodes placed on your skin, the electrode sites may itch slightly during the ambulatory EKG recording, and the skin on your chest may look or feel irritated when the electrodes are removed. The recording unit is very lightweight, so carrying it usually is not uncomfortable.
There is no risk from ambulatory EKG monitoring. The electrodes placed on your skin detect only the electrical signals from your heart. No electricity is sent through your body, and there is no possibility of receiving an electric shock.
An ambulatory electrocardiogram (EKG or ECG) is a test that records the electrical signals that control your heartbeat while you do your everyday activities.
The results of ambulatory heart monitoring are compared with your medical history, symptoms, and other test results. You may need to have the test repeated if the results aren't clear.
What Affects the Test
You may not be able to have the test or the results may not be helpful if:
Ambulatory heart monitoring is most effective when you are able and willing to carefully follow instructions throughout the monitoring period.
If you tend to pass out from a heart problem, your doctor will choose a monitor that will record these episodes. The continuous recorder and the loop recorder work best for people who pass out when they have symptoms of a heart problem. The loop recorder is not useful if you lose consciousness for more than a few minutes or if you are so confused when you wake up that you are unable to start the recorder.
What To Think About
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