What is Holter monitoring?

A Holter monitor is a type of ambulatory electrocardiography (EKG, ECG) machine that allows you to take EKG measurements on a continuing basis (usually 24 hours). Holter monitoring allows you to take EKG measurements while you are away from your doctor's office.

During Holter monitoring, electrodes are attached with adhesive to your chest. A wire runs from each lead to a lightweight battery-powered recording device that you carry either on a strap around your waist or over your shoulder. This recorder measures the electrical signal that your heart produces each time it beats. The EKG machine converts the signal into a graph that represents the activity of your heart's electrical system as waves on the graph. The EKG reading can be displayed electronically on a monitor or printed as line tracings on a piece of paper.

When would my doctor order Holter monitoring?

A standard EKG is done in a doctor's office or hospital. However, your doctor may recommend Holter monitoring because it allows your heart to be monitored for a longer period than would be possible with a standard EKG. This may be important if your heart condition (such as an arrhythmia) does not cause symptoms on a regular basis.

You may carry out all your regular activities while wearing a Holter monitor. In this way, the Holter monitor allows detection of symptoms that occur only when you perform certain activities. A standard EKG does not allow this because the range of activities you perform while at your doctor's office or in a hospital are relatively limited. While wearing the Holter monitor, you will also be asked to keep a diary of all your activities and symptoms.