A pacemaker is a small, battery-powered device that sends out small electrical impulses to make the heart muscle contract. Pacemakers help your heart beat in a regular rhythm and at a normal speed. They are inserted to treat a heart rate that is too slow, too fast, or irregular.

The pacemaker itself consists of a pulse generator and battery that create the electrical impulses. Most pacemakers have wires (leads) that transmit electricity to the heart.

Pacemakers are typically placed under the skin of the chest. Some pacemakers are placed inside the heart and do not have wires.

Temporary pacemakers are used only while a person is in the hospital. A temporary pacemaker is not surgically inserted but is worn outside the body.