A pacemaker is a small, battery-operated device that helps the heart beat regularly and at an appropriate rate.

A pacemaker generally has two parts:

• Generator -- contains the battery and the information to control the heartbeat
• Leads -- wires used to connect the heart to the generator and send the electrical impulses to the heart to tell it to beat

Two kinds of pacemakers -- transcutaneous and transvenous pacemakers -- are only used in emergency situations. They are not considered permanent pacemakers.

A permanent or implantable pacemaker is placed underneath the skin and then connected to your heart. Today's generators weigh a little less than an ounce (30 grams). The pacemaker's battery can last about 7 - 8 years. It will be regularly checked by your doctor, and replaced when necessary.

Traditional pacemakers help control the right side of the heart to regulate the heartbeat. This is called AV synchronization.

A special type of pacemaker, called a biventricular pacemaker, works on both sides of the heart. It synchronizes the right and left chambers (ventricles) of the heart and keeps them pumping together. This is called cardiac resynchronization therapy. All of today's biventricular pacemakers can also work as an implantable cardio-defibrillator (ICD).

IMPLANT SURGERY

A pacemaker must be implanted under the skin. This procedure usually takes about 1 hour. You will be given a sedative to help you relax. However, you will be awake during the procedure. You will receive pain medicine during the procedure.

A small cut is made, usually on the left side of the chest. The health care provider uses x-rays to place the wires (leads) in the heart. After the leads are in place, they are connected to the pacemaker. The pacemaker is placed into the chest area, and the skin around it is closed with stitches. Most patients go home within 1 day of the procedure.

COMPLICATIONS

Complications of pacemaker surgery include:

• Abnormal heart rhythms
• Bleeding
• Dropped lung (uncommon)
• Infection
• Puncture of heart leading to bleeding around the heart (rare)

A pacemaker can usually sense if the heartbeat is above a certain level. At that point it will automatically turn off. Likewise, the pacemaker can sense when the heartbeat slows down too much. It will automatically turn back on in order to start pacing again.

WHY IT IS USED

A pacemaker is often the treatment of choice for people who have a heart condition that causes their heart to beat too slowly (bradycardia).

Less commonly, pacemakers may also be used to stop an abnormally rapid heart rate (tachycardia).

Biventricular pacemakers have been used to treat severe heart failure.

INTERFERENCE

There are only a few devices in the environment today that can interfere with a pacemaker.

• Arc welding equipment and equipment with powerful magnets have the potential to interfere with the pace generator.
• Cell phones in the U.S. do NOT interfere with pacemakers. However, you should still keep them away from the pacemaker area (for example, do not store your cell phone in your shirt pocket).
• Most home appliances, such as a microwave, do NOT interfere with a pacemaker.

The American Heart Association recommends that people with a pacemaker pay close attention to their surroundings to make sure there are not any devices that may interfere.

You should always carry identification with you that says you have a pacemaker.

If you have a pacemaker, you will need to follow up with a cardiologist on a regular basis. During visits, the health care provider will make sure that the pacemaker is working properly. This is a painless procedure that takes several minutes.

Most of the time, problems can be fixed using the programmer. Most modern pacemaker generators can last for a decade or more.

Hayes DL, Zipes DP. Cardiac Pacemakers and Cardioverter-Defibrillators. In: Libby P, Bonow RO, Mann DL, Zipes DP. Libby: Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 34.