A healthy person may notice that their heart beats regularly about 60 to 80 times each minute. The heart beats regularly, and responds to changes such as exercise and sleep, because of special heart cells called pacemakers. These cells send electrical impulses throughout the heart. The impulses cause the heart muscle to contract. This squeezes blood from the heart to the body and the lungs.

If a heart attack, infection, medications, or a disease damages the heart, the pacemaker cells may not work properly. If the pacemaker cells do not send impulses often enough, other parts of the heart will take over. In this case, the heartbeat is often slower than it needs to be. A slow heart rate is called bradycardia. The heart may not pump enough blood for the body's needs. This may result in feeling lightheaded, tired or faint. At other times, the heart may beat irregularly or too rapidly. A rapid heart rate is called a tachycardia. A person with a tachycardia may feel that their heart is racing. If the heart beats too fast it can also fail to pump enough blood.

Some abnormal heartbeats are little more than an annoyance. Others can be very severe. If the part of the heart that pumps the blood, the ventricles, beats too rapidly, too irregularly, or stops beating, the person could die.

The diagnosis of abnormal heartbeats is usually made with an electrocardiogram, also called an ECG. If the irregular heart rate is very common, it may be seen on a routine ECG in the doctor's office. Sometimes a Holter Monitor will be used to for 24 to 48 hours to record the ECG. If the abnormal heartbeat is a rare event, an event monitor that records the heartbeat whenever a person presses a button will be used. It can also send the ECG over the telephone to the doctor's office.

There are many causes for an abnormal heartbeat. Besides heart attacks, infections, and diseases, drugs can cause abnormal heartbeats. So can stimulants, such as caffeine. A person can also be born with an abnormal heartbeat.

The treatment of abnormal heartbeats depends on the cause. Stopping stimulants, such as tea and coffee, may help. Medications may be needed to stabilize the heart rate. If the heart is too slow, a pacemaker can be used. If the heart beats too irregularly or too fast, surgery or a special device to shock the heart may be needed.

For more information, contact your American Heart Association office or call (800) 242-8721.

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