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Pacemakers save lives and make living more comfortable

James Dwyer, M.D.

There are areas in the heart called pacemakers that send electrical signals to the rest of the heart, setting the speed or pace of the heartbeat. These pacemakers speed the heart up during exercise or hard work and slow it down again during rest. If natural pacemakers are injured or fail to do their job, a miniature medical device called a cardiac pacemaker can be implanted in the chest wall.

What is the body’s natural pacemaker?

The heart's "natural" pacemaker is called the sinoatrial (SA) node or sinus node. It's a small mass of specialized cells in the top of the heart's right atrium (upper chamber). It makes the electrical impulses that cause your heart to beat. A chamber of the heart contracts when an electrical impulse moves across it. For the heart to beat properly, the signal must travel down a specific path to reach the ventricles, the heart's lower (pumping) chambers.

When the heart’s natural pacemaker is defective, a person’s heartbeat can be too fast, too slow or irregular. Or, the heart's electrical pathways also may be blocked.

What is an artificial pacemaker?

An "artificial pacemaker" is a small, battery-operated device that primarily keeps the heart beat from going to slow. Some are permanent (internal) and some are temporary (external). Artificial pacemakers range from simple to sophisticated.

• A pacemaker sends electrical impulses to the heart to help it pump properly. An electrode is placed next to the heart wall and small electrical charges travel through the wire to the heart.
• Most pacemakers are demand pacemakers, meaning they have a sensing device which turns the signal off when the heartbeat is above a certain level, and back on when the heartbeat is too slow.

Placement of a pacemaker 

Pacemaker implantation usually takes place in a Cardiac Catheterization Lab while the patient is sedated, but awake. The patient is given local anesthesia so there is no pain. The pacemaker usually is implanted in the upper chest and the wire leads are threaded through a vein into the heart. The battery is attached to the leads and placed under your skin. The leads must touch the inside of the heart so the electrical signals can be carried back and forth between the heart and the battery. In some cases, you may need a temporary pacemaker. A temporary pacemaker is placed outside of the body and is removed once the permanent pacemaker is implanted.

Side effects of artificial pacemakers

There are few side effects or surgical complications associated with artificial pacemakers. To varying degrees, all pacemakers are sensitive to electrical interference from strong magnetic fields, electrical generators and similar equipment, depending upon how well-shielded they are. Individuals are encouraged to carry a letter or identification card stating that they have an artificial pacemaker. They also should inform their dentist and other healthcare providers of their condition. Like any man-made device, they’re subject to failure and do need to be checked regularly.

James Dwyer, M.D., is the medical director of the Heart & Vascular Center of Northern Arizona. Dr. Dwyer specializes in cardiac catheterization and coronary interventions including pacemaker insertion.