A Holter monitor is a small, wearable device that records your heart rhythm. You usually wear a Holter monitor for a 24 hour period. During that time, the device will record all of your heartbeats. A Holter monitor test is usually performed after a traditional test to check your heart rhythm (electrocardiogram or ECG) isn't able to give your doctor enough information about your heart's condition. Its extended recording period is useful for observing occasional cardiac rythym changes which would be difficult to identify in a shorter period of time. For patients having more transient symptoms, a cardiac event monitor can be worn for an extended time period, often a week or more.
A Holter monitor has electrodes that are attached to your chest with adhesive and then are connected to a recording device that is attached to your belt or hung around your neck. Your doctor uses information captured on the Holter monitor's recording device to figure out if you have a heart rhythm problem.
While wearing a Holter monitor may be a little inconvenient, it's an important test that may help your doctor diagnose an abnormality in your hearts rythym.