Holter and Event Monitors

Holter and event monitors are medical devices that record the heart's electrical activity. Doctors most often use these monitors to diagnose arrhythmias. These are problems with the speed or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or irregularly.

Holter and event monitors also are used to detect silent myocardial ischemia. In this condition, not enough oxygen-rich blood reaches the heart muscle. "Silent" means that no symptoms occur.

These monitors also can check whether treatments for arrhythmia and silent myocardial ischemia are working.

How the Test is Performed

Electrodes (small conducting patches) are stuck onto your chest and attached to a small recording monitor. You carry the Holter monitor in a pocket or small pouch worn around your neck or waist. The monitor is battery operated.

While you wear the monitor, it records your heart's electrical activity. You should keep a diary of what activities you do while wearing the monitor. After 24 - 48 hours, you return the monitor to your doctor's office. The doctor will look at the records and see if there have been any irregular heart rhythms.

It is very important that you accurately record your symptoms and activities so that the doctor can match them with your Holter monitor findings.

How to Prepare for the Test

There is no special preparation for the test. Your doctor will start the monitor. You'll be told how to replace the electrodes should they fall off or become loose.

Tell your doctor if you are allergic to any tape or other adhesives. Make sure you shower or bathe before you start the test. You will not be able to do so while you are wearing a Holter monitor.

Why the Test is Performed

Holter monitoring is used to determine how the heart responds to normal activity. The monitor may also be used:

• After a heart attack
• To diagnose heart rhythm problems
• When starting a new heart medicine

It may be used to diagnose:

• Atrial fibrillation/flutter
• Multifocal atrial tachycardia
• Palpitations
• Paroxysmal supraventricular tachycardia
• Reasons for fainting
• Slow heart rate (bradycardia)