ICD Replacement: What Cheney Faces

Later this year, Vice President Dick Cheney will have his internal heart-regulating device surgically replaced, according to an announcement his office issued today.

The device is functioning normally so far, and the replacement procedure is considered routine. But research shows that such procedures are not without their risks.

What's an ICD?

According to the American Heart Association, an ICD, or implantable cardioverter defibrillator, is similar to a pacemaker. It monitors heart rate and sends an electric jolt to the heart muscle when it senses an irregular rhythm.

Many ICDs also record the heart's electrical patterns whenever an abnormal heartbeat occurs, saving the information for doctors to review later.

The devices are powered by a wallet-size generator, which is usually implanted beneath the skin near the shoulder.

In the United States, about 135,000 patients receive defibrillators each year to prevent sudden heart attack. These patients can expect to have their defibrillators replaced through surgery every five to seven years, because the batteries wear out.

Newer versions of these devices are small enough to be installed through blood vessels, eliminating the need for open-chest surgery.

What Are the Risks?

According to the U.S. Food and Drug Administration, potential risks from ICD surgery include infection, bleeding and bruising. More rarely, ICD surgery can lead to complications, including stroke, heart attack, blood clots, or perforation of a major vessel, a lung or the heart muscle.

Also, though many doctors view defibrillator replacement as a routine procedure, a study last year in the Journal of the American Medical Association showed that one in 50 patients need to have their replacement device taken out due to severe post-surgery infections.

The Canadian study further revealed that the overall rate of complications -- including those that did not necessitate the removal of the devices -- turned out to be three to five times higher than expected.

Overall, 43 of the 533 patients studied -- 8.1 percent -- experienced infections and other complications within three months of their operations. Thirty-one of these patients had severe complications, and two died.

The findings followed warnings issued in 2005 by defibrillator manufacturers Medtronic Inc. and Guidant Corp. about flaws in their defibrillators.

For more information, visit the American Heart Association ICD patient information page.