A healthy person who is resting may notice that their heart beats regularly about 60 to 80 times each minute. When they exercise, their heart rate may increase. This is because the body needs more blood. When they sleep, their heart rate may decrease. Occasionally, even in normal people, the heart may skip a beat.

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 and pump blood to the body and the lungs.

If the heart is damaged by a heart attack, infection, or other disease, these natural pacemaker cells may not work properly. When this happens, they may fire unevenly or not at all. If these 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. If the heart rate is too slow, the heart may not pump enough blood for the body's needs. In this case the person might feel lightheaded or may pass out. Sometimes if the pacemaker cells do not send impulses, the heart may begin to beat irregularly. When this happens, the heart may not pump blood effectively. The person may also feel these erratic beats as palpitations.

If the body's natural pacemaker is not sending proper signals to the heart muscle, doctors may suggest an artificial pacemaker. A pacemaker is a battery-operated machine that tells the heart muscle when to beat. Modern pacemakers are usually placed under the skin in a patient's chest. Wires connect to the heart. One set of wires tells the pacemaker what the heart's contraction rate is. Another set of wires tells the chambers in the heart to contract if the rate is too slow or too erratic. Pacemakers can be set to increase the heart rate if the body needs more blood and to slow it down if the body is resting.

Pacemakers have allowed many patients who were handicapped by slow heartbeats to lead normal lives. The pacemaker battery usually last 4 to 12 years. Doctors can check on the pacemaker by examining a patient's ECG. They can also examine a pacemaker by placing a special sensor over the device. This sensor can transmit information over the telephone, so the patient does not have to visit the doctor.For more information, contact your Heart Association office or call (800) 242-8721.

Choose a Health Topic Category Aging Alcohol Problems Allergies Arthritis Back & Neck Problems Blood & Circulatory Problems Bones, Joints & Muscles Brain & Nervous System Cancer Cardiovascular Health Child Health & Development Common Illnesses Cosmetic & Reconstructive Surg Dental Health Diabetes Digestive System Drug Abuse Ear, Nose & Throat Eating Disorders Exercise & Fitness Eyes & Vision Family Planning Foot Care General Health Genetic Disorders & Birth Defects Headaches Health Quizzes Hearing HIV Infections / AIDS Hormonal Disorders Infectious Diseases Medications Men's Health Mental & Emotional Health Nervous System Newborn Care Nutrition Parenting & Family Life Personal Safety Pregnancy & Childbirth Preparing for Emergencies Respiratory Problems Sexually Transmitted Diseases Skin Health Smoking Sports Medicine Stress & How to cope Surgery Symptoms Teenage Concerns Test & Examinations Urinary and Genital Systems Weight Control Women's Health   Go