MONDAY, Oct. 15 (HealthDay News) -- On Monday, Medtronic -- a leading maker of implantable defibrillators -- voluntarily stopped distribution of Sprint Fidelis electronic leads for the devices, because it said the wires could fracture, potentially triggering cardiac events.

The news may have hundreds of thousands of Americans with implanted defibrillators wondering what to do next.

But experts said that for most patients, there's certainly no need to panic.

The electronic leads in question are small electronic wires implanted into the heart that send out information on the heart's rhythm to the defibrillator. According to Medtronic, a fractured lead could result in the defibrillator delivering an unnecessary electrical jolt to the heart, or failing to deliver a shock when it's actually needed.

Defective Sprint Fidelis leads have been implicated in hundreds of malfunctions and may have played a role in five deaths, according to The New York Times.

Right now, Minneapolis-based Medtronic is recommending against implanting these leads in any new patients. But the company -- along with many heart rhythm experts -- is not advising that the leads be removed from patients who already have them.

There are some 268,000 Sprint Fidelis leads currently in use, either in defibrillators made by Medtronic or in those made by other manufacturers.

"This is an important problem," said Dr. Douglas Zipes, a past president and spokesman for the American College of Cardiology. "Anyone with a defective lead now has to have that lead removed and replaced," he said.

That said, Zipes believes that most people will have properly functioning leads and will not need to have them replaced. Anyone with a Sprint Fidelis lead should have it checked out by their doctor, however.

"If the lead is functioning normally, that individual should simply be followed," Zipes advised.

Another expert agreed. "This is a very manageable problem," said Dr. Bruce D. Lindsay, president of the Heart Rhythm Society. Unless the lead is fractured, there is no need to have it replaced, he said.

Lindsay said that patients normally have their defibrillator checked every three months. With the newest devices, patients can even have their defibrillator checked from home via phone. "We can look at that information just as if they came to the clinic," he said.

To find out if you have one of these leads, all you have to do is look at the card that your doctor gave to you after the defibrillator was implanted, Zipes said.

Based on their data, Medtronic said the risk to any one patient is very small.

"These fractures happen at a low rate, and most patients will never experience a fracture," said Medtronic spokeswoman Marybeth Thorsgaard. "Thirty-month data suggests a fracture rate of less than 2.5 percent," she said.

Thorsgaard agreed that patients with these leads should talk with their doctors about the problem. "Actions can be taken to program the device that can reduce the risk to patients and improve monitoring by physicians," she said. This includes an audible warning indicating that a lead is broken, she added.

Implantable cardioverter defibrillators and Cardiac Resynchronization Therapy-Defibrillators are used to treat abnormal heart rhythms that can cause the heart to stop. These devices shock the heart back into normal rhythm by sending a pulse of energy through the lead connected to the heart.

Medtronic is not suggesting that everyone with its Sprint Fidelis leads needs to have them replaced. This is also the advice of several professional groups such as the Heart Rhythm Society and the American College of Cardiology.

Dr. Daniel Schultz, director of the U.S. Food and Drug Administration's Center for Devices and Radiological Health, also offered some reassurance to patients. "We know it can be frightening for a patient to learn that a product they rely on so much might have a serious defect," he said in a statement released Monday. "However, patients can be assured that the likelihood of fracture is very low, and FDA is committed to ensuring that the risk to patients is minimized."

Schultz added that his agency will soon be issuing a "recall classification" regarding the Sprint Fidelis leads. This does not mean that the devices must be surgically removed, he said, only that new ones should not be implanted in patients.

"Neither FDA, Medtronic, nor representatives of the Heart Rhythm Society, recommend the routine surgical removal of a fractured lead, because removal carries risks," Schultz said. "Instead, physicians should weigh the benefits and risks of either continuing to use the lead with careful monitoring or capping the lead so it is no longer useable and implanting a different model."

Schultz also noted that "a small number of Sprint Fidelis leads are used with defibrillators made by manufacturers other than Medtronic." Patients who are unsure as to whether they are using the Sprint Fidelis lead should consult with their physician, he said.

If the lead is fractured, Medtronic will provided a new lead free of charge. The company has also pledged to pay affected individuals up to $800 in unreimbursed medical expenses, Thorsgaard said.

Zipes described the lead fracture as a relatively minor problem for such a complex device.

"These devices work 99 percent of the time," Zipes said. "Without a device, the patient faces a 100 percent chance of dying, but, with the device, the patient faces a 99 percent chance of living," he said.

Vice President Dick Cheney uses a Medtronic defibrillator, but it was implanted in 2001, before these leads were introduced, The New York Times reported.

More information

For more information on the Medtronic recall, visit the U.S. Food and Drug Administration.