Types of Holter and Event Monitors

Holter Monitors

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

A Holter monitor is about the size of a large deck of cards. You can clip it 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 pick up your heart's electrical signals, and the monitor records your heart's rhythm.

Wireless Holter Monitors

Wireless Holter monitors have a longer recording time than standard Holter monitors. The wireless version records your heart's electrical activity for a preset amount of time.

These monitors are called wireless because they use a cell phone to send the data to your doctor's office. This happens automatically at certain times. These monitors still have wires that connect the device to the sensors stuck to your chest.

You can use a wireless Holter monitor for days or even weeks until signs or symptoms of a heart rhythm problem occur. These monitors usually are used to detect heart rhythm problems that don't occur often.

Although wireless Holter monitors work for longer periods, they have a down side. You must remember to write down the time of symptoms, so your doctor can match it to the heart rhythm recording. Also, the batteries in the wireless monitor must be changed every 1 to 2 days.

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 that are stuck to your chest using sticky patches.

Unlike Holter monitors though, event monitors don't continuously record the heart's electrical activity. They only record when symptoms occur. For many event monitors, you need to start the monitor when you feel symptoms.

Event monitors tend to be smaller than Holter monitors because they don't need to store as much data.

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

Postevent Recorders

Postevent recorders are among the smallest event monitors. You can wear a postevent recorder like a wristwatch or carry it in your pocket. The pocket version is about the size of a thick credit card. These recorders don't have wires that connect the device to chest sensors.

When you feel a symptom, you start the recorder. A postevent recorder only records what happens after you start it. It may miss a heart rhythm problem that occurs before and during the onset of symptoms. Also, it may be hard to start the monitor when a symptom is in progress.

In some cases, this missing data would have helped your doctor diagnose the heart rhythm problem.

Presymptom Memory Loop Recorders

Presymptom memory loop recorders are the size of a small cell phone. They're also called continuous loop event recorders.

You can clip this event monitor to your belt or carry it in your pocket. Wires connect the device to sensors on your chest.

These recorders are always recording and erasing data. When you feel a symptom, you push a button on the device. The normal erase process stops. The recording will show a few minutes of the data from before, during, and after the symptom.

In some cases, this makes it possible for your doctor to see very brief changes in your heart's rhythm.

Autodetect Recorders

Autodetect recorders are about the size of the palm of your hand. Wires connect the device to sensors on your chest.

You don't need to start an autodetect recorder during symptoms. These recorders detect abnormal heart rhythms and automatically record and send the data to your doctor's office.

Implantable Loop Recorders

You may need an implantable loop recorder if other event monitors can't provide enough data. Implantable loop recorders are about the size of a pack of gum. This type of event monitor is inserted under the skin on your chest. No wires or chest sensors are used.

The device records either when you activate it or automatically when symptoms occur. It depends on how your doctor programs it. Devices may differ, so your doctor will tell you how to use it. In some cases, a special card is held close to the recorder to start it.