A pacemaker uses electrical pulses to keep the heart in rhythm, neither beating too slow nor too fast, and a defibrillator shocks the heart if it detects a dangerous rhythm disturbance, preventing cardiac arrest. A defibrillator also has the capabilities of a pacemaker, regulating heart rhythm if necessary.
Pacemakers and defibrillators are small devices implanted in the chest. The patient is admitted to the hospital for the procedure. During minor surgery, the doctor makes an incision, places the device under the skin, attaches its wires to veins that lead to the right side of the heart, and then closes the incision.
Pacemakers and defibrillators are custom programmed to meet the medical needs of the individual patient. Each is activated only by specific heart rhythm activity, and many defibrillators record the electrical patterns of the heart during an abnormal cardiac event to help the doctor plan appropriate treatment. During follow-up visits, they are read and programmed through the skin, using a computer program, so no further surgery is necessary unless the lithium battery needs replaced.
People with pacemakers or defibrillators must avoid large magnetic fields, such as those found with Magnetic Resonance Imaging (MRI), ultrasounds or CT scans. They do not have to worry about using microwaves or other household appliances.