A Holter monitor is a device that records your heart’s rate and rhythm, usually over a period of 24 to 48 hours. The monitor is a small, box-shaped electronic device that is connected with wires (leads) to sticky patches (electrodes) that are placed on the skin of your chest. The monitor is attached to a strap that goes around your shoulder or waist to hold it close to your body.

How Does It Work?

A Holter monitor, like an electrocardiogram (ECG or EKG), reads your heart’s electrical activity. Your heart has an electrical system that functions like a natural pacemaker. Electrical signals travel through the chambers of the heart to cause it to beat. If the heart’s natural electrical system is not functioning correctly, an abnormal heartbeat (arrhythmia) may result. This may be the cause of symptoms of your heart racing, palpitations, or feeling faint.

The electrodes on the Holter monitor detect the heart’s electrical activity and transmit this information through the leads to the monitor. The battery-operated monitor continuously records this data.

Whenever you experience heart symptoms while wearing the monitor, you will write down the symptom, date and time, and what activity you were doing at that time. Your cardiologist will compare your symptom log against the data gathered by the monitor to see how your heart was responding when you performed certain activities.

How Is It Performed?

You will be fitted for a Holter monitor at your cardiologist’s office. Once you have been fitted, you will wear the monitor day and night for the amount of time indicated by your cardiologist. You will be asked to continue your regular activities and to log these activities and any symptoms.

Before you go to your cardiologist’s office for the monitor fitting, you may wish to take a shower or bath. You will not be able to do so once you are wearing the monitor, which should not be removed during the period of the test and which can also be damaged by water. Some patients may need to have small portions of hair on their chest shaved to allow the electrodes to connect properly. A nurse will stick the electrodes to your skin. Once you are wearing the monitor, the electrodes and wires will be hidden by your clothing. You may be given instructions on how to replace the monitor’s batteries if necessary.

After the testing period is over, you will return the Holter monitor to the cardiologist’s office and give your activity/symptom log to the cardiologist for review in conjunction with the monitor data.

Is It Safe?

Wearing a Holter monitor is safe. However, if you have an allergy to any adhesives, be sure to let the cardiologist and nurse know, as the electrodes are attached to the skin with adhesive.

Questions to Ask Your Doctor About Holter Monitoring

The following questions can help you talk to your physician about wearing a Holter monitor. Consider printing out or writing down these questions and taking them with you to your appointment. Taking notes can help you remember your physician’s response when you get home.

• What information will a Holter monitor provide about my heart health?
• What information should I log while I am wearing the Holter monitor?
• Will I need to replace batteries in the monitor?
• When do I return the monitor?
• What happens next if the data from the Holter monitor shows a potential problem with my heart’s rhythm?

Please print this list of questions here. Take them with you to the doctor and share them with friends and loved ones when you are encouraging them to see their doctors.