Holter/Event Recording In order to diagnose various heart conditions, your child's doctor may want to monitor your child's heart beat over a period of time. Following are several ways a pediatric cardiologist may monitor your child's heart beat. Holter Recorder (Ambulatory ECG Monitoring) This is a way to detect suspected arrhythmias (irregular heart beat). It means wearing a small, portable, battery operated ECG recorder, called a Holter monitor. It records continuous ECG information, for one to two days, on a tape. This recorded data is then analyzed by your child's doctors. Event Recorder An event monitor is a small portable monitor that is activated when your child has "an event," that is, he or she experiences symptoms of a heart problem (an irregular heart beat, for example). The recorded data can be sent over the phone to your child's doctors for analysis. Loop Recorder A loop monitor continuously monitors your child's heart rate and rhythm. When your child has "an event," that is, he or she experiences symptoms of a heart problem (an irregular heart beat, for example), they press a button to record the "event." The monitor will then record for a set period of time prior to the "event" and a set period of time after the "event."