If the signals are not sent often enough, other parts of the heart will react, causing a slower, irregular, or faster heart rate. A slower heart rate may not pump enough blood for the body's needs. This may result in feeling lightheaded, tired, or faint. With an irregular or rapid heart rate, a person may feel that his heart is racing or skipping beats. When the heart beats too fast, it can fail to pump enough blood.
Some abnormal heartbeats are little more than an annoyance, while others can be life-threatening.
If the part of the heart that pumps the blood beats too rapidly, too irregularly, or stops beating, the person could faint or even die. If the irregular heart rate happens frequently, it may be seen on a routine EKG in the doctor's office. Sometimes a device called a Holter monitor will be worn for 24 to 48 hours to record a longer EKG so that the abnormal beats can be seen. There are many causes for an abnormal heartbeat. Besides heart attacks, infections, and diseases, some drugs can also cause abnormal heartbeats.