Pacemaker

What Is It?

A pacemaker is an implanted medical device that regulates your heartbeat electronically. It monitors your heart's natural rhythm and, when necessary, it generates a painless electric impulse, called a pacing pulse, which triggers a heartbeat.

Your pacemaker's activity is governed by electronic programming that is tailored to the needs of your heart. Early pacemakers were implanted to treat bradycardia, an abnormally slow heartbeat. Now, however, pacemakers can be programmed to treat a variety of heart problems, including heart failure.

The electronic control center of your pacemaker — the part that is programmed by your doctor — is called the pulse generator. The pulse generator is a unit encased in titanium that usually is implanted under the skin below your collarbone. In most cases, the unit is small, often weighing less than 30 grams (about 1 ounce). A lithium iodide battery inside the generator lasts five to 12 years, with an average of seven to eight years. Other sophisticated electronic components are responsible for:

• Sensing your natural heartbeat
• Generating a pacing pulse according to how the unit is programmed
• Keeping an electronic record of your heartbeat and your pacemaker's activity

The pulse generator is attached to one or more wires called leads. These are threaded through large blood vessels in your upper chest into your heart. At the ends of the leads are small electrodes that attach to the inner surface of your heart. These electrodes are responsible for picking up your heart's natural electric signals. In addition, the pacing pulse from the pulse generator travels along the leads to your heart muscle.

In the United States, about 200,000 pacemakers are implanted each year. In addition, approximately 175,000 pacemakers are replaced, removed or repaired each year. Based on data from the U.S. National Institutes of Health, the current average cost of a pacemaker in the United States is more than $10,000. Many studies confirm that pacemaker implantation is a cost-effective and safe way to treat certain heart problems.

What It's Used For

Under normal conditions, the signal for a heartbeat originates in your heart's sinus node, the body's natural pacemaker, located in the upper portion of your heart's right atrium. From the sinus node, the signal normally travels to the atrioventricular node (AV node) between the two atria, and then downward to the ventricles. Once the signal arrives at the ventricles, it triggers a contraction of the heart muscle and produces a heartbeat.

If your sinus node is not generating natural signals properly, or if there is interference along the normal pathway to the ventricles, your doctor may recommend a pacemaker. Specifically, you may need a pacemaker if you have: