The Holter monitor is a type of
electrocardiogram (ECG or EKG) used to monitor the ECG tracing continuously for a period
of 24 hours or longer. A standard or "resting" ECG is one of
the simplest and fastest procedures used to evaluate the heart. Electrodes
(small, plastic patches) are placed at certain locations on the chest
and abdomen. When the electrodes are connected to an ECG machine by lead
wires, the electrical activity of the heart is measured, interpreted,
and printed out for the doctor's information and further interpretation.
Event monitoring is very similar to Holter monitoring, and is often ordered
for the same reasons. With an event monitor, you wear ECG electrode patches
on your chest, and the electrodes are connected by wire leads to a recording device.
Unlike the Holter monitor, however, which records continuously throughout
the testing period of 24 to 48 hours, the event monitor records when you
feel symptoms and trigger the monitor to record your ECG tracing at that
time. An auto-trigger event monitor may be used to record rhythms when
symptoms are rare or suspected to occur during sleep. The auto-trigger
event monitor automatically records rhythm events that are faster or slower
than normal and can also be manually activated if you experience symptoms.