The heart is equipped with its own "wiring." It has specialized cells that conduct nerve impulses to keep the heart beating regularly at just the right rate. The heart can speed up or slow down in response to the body's need for oxygenated blood. Coronary artery disease or structural problems with the heart muscle, along with other conditions, can cause problems with the heart's conduction system.
You may feel a conduction problem as heart palpitations or a fluttering in your chest. The clinical term for this is "arrhythmia" or "dysrhythmia." This means the heart beats too quickly, too slowly or with an irregular pattern. Sometimes you will not have any symptoms that this is occurring.
The standard electrocardiogram (EKG) measures the heart's electrical activity, and may pick up an arrhythmia. But it only records the heart for a few seconds. A Holter monitor checks the heart's electrical activity over several hours.
What is this test?
Holter monitoring is a continuous monitoring of heart rate and rhythm during your usual daily activities, usually for a 24-hour period. It is also called continuous ambulatory electrocardiographic monitoring.
Why this test may be performed
A Holter monitor is used to identify heart rhythm disturbances, which may come and go at various times throughout the day or night. It is often used to match up symptoms with a documented abnormal heart rhythm. These symptoms can include dizziness, palpitations, shortness of breath or chest pain. The Holter monitor also can evaluate if an artificial pacemaker is working properly.
What this test involves
A Holter monitor is applied in a doctor's office, cardiology suite or at the hospital bedside. Electrodes are placed on the front of the chest and the electrode wires are then attached to a small, portable, battery-operated recorder. The recorder is held in place by a shoulder strap or belt that can be worn around the waist. The recorder continuously records and stores the heart rhythm, usually for 24 hours. You are usually encouraged to do your normal daily activities. During this time, you also keep a log for recording activities such as eating, walking, driving and taking medication. You also record symptoms such as palpitations, dizziness and shortness of breath, noting when they occur. Once the monitor has been removed, a doctor analyzes the heart rhythm and activity log.
What are the risks/precautions for this test?
A Holter monitor is a noninvasive test. It is painless and there are no risks. Shower or bathe before the electrodes are applied to the chest, as you won't be able to while the test is in progress.
What the results may tell you
A Holter monitor may detect a disturbance in heart rhythm that is not seen on a single, resting EKG tracing. It allows the doctor to match specific symptoms with the electrical activity of the heart. A Holter monitor can detect rhythm disturbances that come and go. Malfunctions in artificial pacemakers can also be detected.
Created on 08/01/2001
Updated on 05/12/2010
- American Heart Association. Diagnosing arrhythmias.
- American Heart Association. What are Holter, event and transtelephonic monitors?
- National Heart Lung and Blood Institute. How are arrhythmias diagnosed?
- American College of Cardiology. Cardiosmart: Holter and event monitors.