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Definition of Pacemaker and Function
Pacemaker is a small, implanted electronic device that emits electrical impulses to maintain a regular heart rate.
The most frequent use of a pacemaker is to treat bradycardia, an arrhythmia in which the heart rate is persistently below 60 beats per minute.
A pacemaker may also be an effective treatment for obstructive cardiomyopathy, in which thickening of the heart wall interferes with the ability of the myocardial cells to convey electrical impulses.
Implanting the Pacemaker
The cardiologist implants the pacemaker during a brief procedure, with local anesthetic and a mild sedative to make the person comfortable. A standard pacemaker has two components: the pacing lead and the computerized control unit.
The pacing lead extends through a blood vessel into the heart, where the cardiologist positions it against the wall of the heart, usually the right ventricle or the right atrium. Some pacemakers may have two pacing leads, with one going into the right atrium and the other to the right ventricle.
The cardiologist then makes a small incision just below the collarbone to create a pocket that holds the control unit, and connects the pacing lead to the control unit. The cardiologist then programs the control unit to deliver an electrical impulse, a very mild electrical shock, when the heart rate falls below a specific threshold.
Most pacemakers are set to respond “on demand,” which means they emit pacing impulses only when the heart fails to generate them itself. The incision over the pacemaker control unit heals in about two or three weeks, leaving a barely noticeable protrusion.
Living With a Pacemaker
Some people notice when the pacemaker releases an electrical impulse, though most people are not aware. The “on demand” feature of current pacemakers allows the heart to accelerate its rhythm during physical exercise, sexual activity, and other situations in which the heart would naturally beat faster.
Certain medical and dental equipment, such as magnetic resonance imaging (mri), machines that deliver radiation therapy, and some dental drills also can interfere with pacemakers. Though earlier models of pacemakers were sensitive to electromagnetic interference from household appliances and other electronic devices, this is no longer the case.
Only high-power devices such as welding equipment or power tools emit enough electromagnetic energy to disrupt a pacemaker. There is some question about the potential of interference from cellular and portable telephones.
To be safe, cardiologists recommend keeping the phone at least six inches from, and holding it to the ear opposite, the pacemaker’s control unit. Pacemakers run on lithium batteries and can function for about seven years before they need to be replaced.
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