Hands holding output from ecg with stethoscope in the background.

What is a Holter Monitor?

A Holter monitor is a small of portable, battery-powered medical device that measures the heart’s activity such as rate and rhythm. This testing is ordered when your provider needs more information about the functioning of your heart than a routine electrocardiogram (EKG) can give him or her. Holter monitoring (24h) refers to a 24-hour, continuous test to record your heart rate and rhythm. A patient wears the Holter monitor for 24 hours as they go about their normal daily routines.

How it Works

The Holter monitor is small, slightly larger than a deck of playing cards. Several leads, or wires, are attached to the monitor. The leads connect to electrodes that are placed on the skin of your chest with a glue-like gel. The metal electrodes conduct your heart’s activity through the wires into the Holter monitor. This device has electrodes and electrical leads exactly like a regular electrocardiogram.

A small pouch holds the monitor itself, which you wear around your neck or clip it to your belt. It’s important to keep the monitor close to your body during the testing period to make sure the readings are accurate.

You are encouraged to participate in your normal activities during the Holter 24-hour test. You will be directed to record your activities in a diary. This helps your provider determine if changes in heart activity are related to your behaviors and movements.

Holter monitor testing is painless. However, be sure to record any chest pain, rapid heartbeat, or other cardiac symptoms you experience during the testing period.

Understanding the Results

After the recommended testing time frame has passed, you will return to your healthcare provider to have the Holter monitor removed. Your doctor will read your activity journal and the results of the monitor. Depending on the results of the test, you may need to undergo further testing before a diagnosis is made.