A pacemaker is a small device that's placed under the skin of your chest or abdomen to help control abnormal heart rhythms. This device uses electrical pulses to prompt the heart to beat at a normal rate. Pacemakers are used to treat heart rhythms that are too slow, fast, or irregular. These abnormal heart rhythms are called arrhythmias. Pacemakers can relieve some symptoms related to arrhythmias, such as fatigue (tiredness) and fainting. A pacemaker can help a person who has an abnormal heart rhythm resume a more active lifestyle.
A pacemaker consists of a battery, a computerized generator, and wires with electrodes on one end. The battery powers the generator, and a thin metal box surrounds both it and the generator. The wires connect the generator to the heart.
The pacemaker's generator sends the electrical pulses that correct or set your heart rhythm. A computer chip figures out what types of electrical pulses to send to the heart and when those pulses are needed. To do this, the computer chip uses the information it receives from the wires connected to the heart. It also may use information from sensors in the wires that detect your movement, blood temperature, breathing, or other factors that indicate your level of physical activity. That way, it can make your heart beat faster when you exercise.
The computer chip also records your heart's electrical activity and heart rhythms. Your doctor will use these recordings to set your pacemaker so it works better at making sure you have a normal heart rhythm. Your doctor can program the computer in the pacemaker without having to use needles or directly contacting the pacemaker.
The wires in your pacemaker send electrical pulses to and from your heart and the generator. Pacemakers have one to three wires that are each placed in different chambers of the heart.
The wires in a single-chamber pacemaker usually carry pulses between the right ventricle (the lower right chamber of your heart) and the generator.
The wires in a dual-chamber pacemaker carry pulses between the right atrium and the right ventricle and the generator. The pulses help coordinate the timing of these two chambers' contractions.
The wires in a triple-chamber pacemaker are used for heart muscle weakness and carry pulses between an atrium and both ventricles and the generator. The pulses help coordinate the timing of the two ventricles with each other.