Guidant Corporation is telling doctors to discontinue use of certain of its implantable heart devices.

This is just as a precautionary measure until further notice. The FDA may classify this action as a recall, they write.

The devices are the Contak Renewal 3 and 4, the Renewal 3 and 4 AVT, and the Renewal RF.

“We have determined that a magnetic switch in these devices may become stuck in the closed position,” says a Guidant news release. That problem could hinder the device’s ability to treat irregular heartbeats and could speed up the depletion of the device’s battery, says Guidant.

Defibrillators are surgically implanted in people who have a type of heart disease that creates the risk of a life-threatening heart arrhythmia (abnormal rhythm). The devices are designed to deliver an electrical shock to the heart to restore normal heart rhythm.

4 Confirmed Cases

Four cases have been confirmed out of about 46,000 of the devices. A fifth is suspected but cannot be confirmed, says Guidant.

In four cases, the device had been implanted; in another, the problem was caught before the device was used.

“In the four occurrences in which the device was implanted, patients and/or physicians were alerted to the condition by audible device tones that signaled the magnetic switch was closed,” says Guidant. All of those devices were replaced.

Guidant’s Recommendations

Patients with the affected devices should contact their doctors or go to the hospital emergency room immediately if they hear tones coming from their device, according to the Guidant news release.

It also notes that Guidant officials recommend that doctors consider programming “Enable Magnet Use” to “OFF” to ensure that appropriate therapy is delivered as needed in the event that the magnet switch becomes stuck in the closed position. If "Enable Magnetic Use" is programmed "ON," as it is on the default settings, and the magnet switch becomes stuck in the closed position, treatment of certain irregular heart rhythms does not occur. Under these conditions the device will then emit tones, and the battery will become depleted.

However, if the "Enable Magnetic Use' is in the “Off" position, and the magnet switch becomes stuck, abnormal rhythms will continue to be treated.

Guidant’s investigation is continuing.

FDA’s Response

The FDA is “pleased” that Guidant is communicating important safety information, says Daniel Schultz, MD, director of the FDA’s Center for Devices and Radiological Health, in a news release.

Schultz says the FDA encourages patients to talk to their doctors about their Guidant devices.

The FDA is working with Guidant on the matter and will share more information “quickly” with the public as it becomes available, says Schultz.

Doctors or patients are asked to report problems with any of these devices to the FDA’s MedWatch program and to Guidant, says the FDA.

Second Guidant Advisory in a Week

On June 17, the FDA said Guidant had issued a voluntary recall on several of its devices:

Prizm 2 DR, Model 1861, manufactured on or before April 16, 2002 Contak Renewal, Model H135, manufactured on or before Aug. 26, 2004 Contak Renewal 2, Model H155, manufactured on or before Aug. 26, 2004 Prizm AVT Vitality AVT Renewal 3 AVT Renewal 4 AVT

Guidant didn’t use the term “recall” last week, or in its latest statement.

For more information on any of the devices, contact Guidant at (866) 484-3268.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: News release, Guidant. News release, FDA. WebMD Medical News: “FDA: Some Guidant Defibrillators Recalled.”