Holter and event monitors are medical devices that record the heart's electrical activity. Doctors most often use these monitors to diagnose arrhythmias (ah-RITH-me-ahs).Arrhythmias are problems with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm.

Holter and event monitors are similar to an EKG (electrocardiogram). An EKG is a simple test that detects and records the heart's electrical activity. It's a common test for diagnosing heart rhythm problems.However, a standard EKG only records the heartbeat for a few seconds. It won't detect heart rhythm problems that don't occur during the test.

Holter and event monitors are small, portable devices. You can wear one while you do your normal daily activities. This allows the monitor to record your heart for a longer time than an EKG.

Some people have heart rhythm problems that occur only during certain activities, such as sleeping or physical exertion. Using a Holter or event monitor increases the chance of recording these problems.

Although similar, Holter and event monitors aren't the same. A Holter monitor records your heart's electrical activity the entire time you're wearing it. An event monitor records your heart's electrical activity only at certain times while you're wearing it.

Types of Holter and Event Monitors:

Holter Monitior

Holter monitors sometimes are called continuous EKGs (electrocardiograms). This is because Holter monitors record your heart rhythm continuously for 24 to 48 hours.

You can clip the holter monitor to a belt or carry it in a pocket. Wires connect the device to sensors (called electrodes) that are stuck to your chest using sticky patches. These sensors detect your heart's electrical signals, and the monitor records your heart rhythm.

Event Monitors

Event monitors are similar to Holter monitors. You wear one while you do your normal daily activities. Most event monitors have wires that connect the device to sensors. The sensors are stuck to your chest using sticky patches.

Unlike Holter monitors, event monitors don't continuously record your heart's electrical activity. They only record during symptoms. For many event monitors, you need to start the device when you feel symptoms. Some event monitors start automatically if they detect abnormal heart rhythms.

Different types of event monitors work in slightly different ways. The doctor will explain how to use the monitor before you start wearing it.

Who Needs a Holter or Event Monitor?

The doctor may recommend a Holter or event monitor if he or she thinks you have an arrhythmia. An arrhythmia is a problem with the rate or rhythm of the heartbeat.

Holter and event monitors most often are used to detect arrhythmias in people who have:
Issues with fainting or feeling dizzy. A monitor might be used if causes other than a heart rhythm problem have been ruled out.
Palpitations that recur with no known cause. Palpitations are feelings that your heart is skipping a beat, fluttering, or beating too hard or fast. You may have these feelings in your chest, throat, or neck.

People who are being treated for heart rhythm problems also may need to use Holter or event monitors. The monitors can show how well their treatments are working.

Heart rhythm problems may occur only during certain activities, such sleeping or physical exertion. Holter and event monitors record your heart rhythm while you do your normal daily routine. This allows your doctor to see how your heart responds to various activities.

What To Expect While Using a Holter or Event Monitor?

Your experience while using a Holter or event monitor depends on the type of monitor you have. However, most monitors have some factors in common.

Recording the Heart's Electrical Activity

All monitors record the heart's electrical activity. Thus, maintaining a clear signal between the sensors (electrodes) and the recording device is important.In most cases, the sensors are attached to your chest using sticky patches. Wires connect the sensors to the monitor. You usually can clip the monitor to your belt or carry it in your pocket.A good stick between the patches and your skin helps provide a clear signal. Poor contact leads to a poor recording that's hard for your doctor to read.Oil, too much sweat, and hair can keep the patches from sticking to your skin. You may need to shave the area where your doctor will attach the patches. If you have to replace the patches, you'll need to clean the area with a special prep pad that your doctor will provide.You may need to use a small amount of special paste or gel to help the patches stick to your skin. Some patches come with paste or gel on them.Too much movement can pull the patches away from your skin or create "noise" on the EKG (electrocardiogram) strip. An EKG strip is a graph showing the pattern of the heartbeat. Noise looks like a lot of jagged lines; it makes it hard for your doctor to see the real rhythm of your heart.When you have a symptom, stop what you're doing. This will ensure that the recording shows your heart's activity rather than your movement.The doctor will tell you whether you need to adjust your activity level during the testing period. If you exercise, choose a cool location to avoid sweating too much. This will help the patches stay sticky.

Keeping a Diary

While using a Holter or event monitor, the doctor will advise you to keep a diary of your symptoms and activities. Write down what type of symptoms you're having, when they occur, and what you were doing at the time.

The most common symptoms of heart rhythm problems include:
Fainting or feeling dizzy
Palpitations. These are feelings that your heart is skipping a beat, fluttering, or beating too hard or fast. You may have these feelings in your chest, throat, or neck.

Make sure to note the time that symptoms occur, because the doctor will match the data with the information in your diary. This allows the doctor to see whether certain activities trigger changes in your heart rate and rhythm.

Also, include details in your diary about when you take any medicine or if you feel stress at certain times during the testing period.

What To Expect After Using a Holter or Event Monitor?

After you're finished using a Holter or event monitor, you'll return it to your doctor's office or the place where you picked it up.The doctor will tell you when to expect the results. Once your doctor has reviewed the recordings, he or she will discuss the results with you.