Whether your heartbeat is fast, slow, or irregular, thesecardiac devices can help bring it back to normal.

Having a steady, rhythmic heartbeat is something we dependon, but it’s not something we think about much unless there’s a problem. Theheart has its own built-in pacemaker: a collection of special cells known asthe sinoatrial node (sometimes called the sinus node). The sinoatrial nodecreates electrical impulses that initiate the heartbeat; first by prompting theheart’s two upper chambers (atria) to contract, followed by the two lowerchambers (ventricles). This design keeps the heart pumping blood to our bodiesin a strong, steady pattern.

If this natural pacemaker stops working properly, the heartmay beat too quickly, too slowly, or in an irregular rhythm. (An abnormal heartrhythm is referred to as an arrhythmia.) When this happens, artificialpacemakers and/or defibrillators may be needed to regulate the heartbeat and preventmore serious problems from developing.

Picking up the pace

When we’re at rest, our hearts typically beat 60 to 80 timesper minute. In athletes and others in very good physical condition, the heartrate may be even slower. A slow heartbeat is referred to as bradycardia.Bradycardia may not require treatment unless it causes symptoms such asdizziness, fainting, or fatigue. At that point, a pacemaker may be needed tokeep the heart beating at the right rate.

Pacemakers are small, battery-operated devices that areimplanted in the chest near the heart. Wires attached to the pacemaker areplaced in the heart. When the heart rate slows too much, the pacemaker sendselectrical impulses through the wires and into the heart to bring the beat backup.

Defibrillators on duty slow things down

The opposite of bradycardia is tachycardia—a heartbeatthat’s too rapid (more than 100 beats per minute). Yet tachycardia can causedizziness and fainting, much like bradycardia, because whether moving tooquickly or too slowly, the abnormally beating heart does a poor job of movingblood to the brain and other organs. Tachycardia can also cause chest pain andpalpitations (a pounding, rapid heartbeat).

A very fast heartbeat can be more serious if it causesfibrillation. In fibrillation, the heart’s chambers don’t contractnormally—instead, they quiver inefficiently. In atrial fibrillation, the bloodin the atria does not completely empty into the ventricles as it’s supposed towith each heartbeat. The pooling blood in the atria may give rise to bloodclots that can travel to the brain and cause a stroke.

An especially dangerous situation can occur when rapid heartrhythms start in the ventricles, because these arrhythmias can change withoutwarning into ventricular fibrillation—the most serious kind of arrhythmia.During ventricular fibrillation, the heart’s main pumping ventricle quivers butdoesn’t actually beat. As a result, blood isn’t pumped out to the body. Unlessmedical help is available immediately to shock the heart back to a normalrhythm, sudden cardiac death will result.

A person who is prone to life-threatening ventriculararrhythmias may require a small, battery-operated device—not a pacemaker, butan implantable cardioverter defibrillator (ICD). ICDs regulate the heartbeatand deliver a shock to the heart on an as-needed basis to prevent potentiallydeadly heart rhythms from developing.

Like pacemaker implantation, ICD implantation is a minorsurgical procedure in which wires connected to the device are attached to theheart. The ICD itself is a smallmetal box, implanted in the chest or abdomen. The ICD comes equipped with acomputer that sends electric pulses through the wires into the heart when theheart begins to beat in an irregular fashion.

Living with ICDs and pacemakers

The batteries that power pacemakers and ICDs last a longtime—between
5 and 15 years. Replacing the battery requires more surgery, but this operationis simpler than the original implantation procedure.

As with any treatment, there are risks and benefitsassociated with the use of pacemakers and ICDs. For example, pacemakers andICDs can get infected with bacteria. If this happens, the device usually is removed. One large study reportedin Archivesof Internal Medicine (April 9, 2007) found that infections were morelikely to occur with ICDs than with pacemakers.

Whether you have a pacemaker or an ICD, you probably won’thave to restrict your physical activities. However, your doctor may advise youto avoid full-contact activities that could loosen the wires of the device ordamage the device itself.

You’ll still be able to drive, although if you get an ICDyou may be advised not to get behind the wheel until you’ve gone six monthswithout a fainting or near-fainting spell.

Ask your doctor for more information about the do’s anddon’ts of living with a pacemaker or ICD.