Many people have irregular heartbeats, also called arrhythmias, from time to time. The importance of irregular heartbeats depends on the type of pattern they produce, how often they occur, how long they last, and whether they occur at the same time you have symptoms. Because arrhythmias can occur off and on, it may be difficult to record an arrhythmia while you are in the doctor's office.
Physicians tend to order a Holter monitor in these cases since it can continuously record your heart's rhythm for 24 hours. A standard EKG monitors only 40 to 50 heartbeats during the brief period you are attached to the machine while a Holter monitors about 100,000 heartbeats in 24 hours and is likely to find any heart problems that occur with activity.