Holter Monitor and Event Monitor

What is the test?

A Holter monitor is a portable EKG device that records your heart rhythm over time, outside the hospital or doctor's office. Whereas a regular EKG examines your heart's electrical activity for a few seconds, the Holter monitor examines changes over a sustained period of time-usually a 24- to 48-hour period-while you go about your daily activities and even while you sleep. One type of Holter monitor, called an "event monitor," can be used to record rhythms over a longer time, such as a 30-day period. Doctors use Holter monitor or event monitor tests to evaluate symptoms that come and go and that might be related to heart-rhythm changes or coronary artery disease.

How do I prepare for the test?

Men with a lot of hair on their chest will probably have to shave it. Otherwise, there's no special preparation.