INDIANAPOLIS – Guidant Corporation yesterday warned physicians that replacements might be needed for nine pacemaker models made between 1997 and 2000, of which some 28,000 remain implanted in patients worldwide.

The Indianapolis-based company, which last month recalled almost 109,000 defibrillators, released a warning that says a sealing component in the pacemakers has degraded in some cases, resulting in higher-than-normal moisture in the devices and possible malfunction.

About 78,000 of the pacemakers were distributed, with about 18,000 remaining in American patients, the company said in the statement. The devices, which send electrical pulses to the heart to accelerate a slow heartbeat, have a seven- to 10-year life span before they must be replaced.

Guidant said it has identified 69 failures among the pacemakers – all after they had been used for at least 44 months. The models include: Pulsar Max, Pulsar, Discovery, Meridian, Pulsar Max II, Discovery II, Virtus Plus II, Intelis II, and Contak TR.

The company told physicians they should consider replacing the devices for patients who are dependent on the devices. Pacemakers are about the size of two half-dollars held together.

Several patients implanted with the devices have lost consciousness or developed possible heart failure, Guidant said. It reported the death of one person whose pacemaker may have failed, but said the role of the device could not be confirmed as it was not returned for testing.

Food and Drug Administration spokeswoman Julie Zawisza said the agency was evaluating Guidant’s warning. The company said the FDA may classify the warning as a recall. Guidant issued two safety warnings last month for 11 models of defibrillators that were later classified by the FDA as recalls.

Defibrillators, three times the size of pacemakers, are also implanted; they shock the heart back into rhythm when it beats too quickly. Almost 88,000 of the Guidant devices that were recalled remain implanted worldwide.

The problem with Guidant’s pacemakers poses less of a risk for patients than that of its defibrillators, the chief of cardiology at Emory Crawford Long Hospital in Atlanta, Dr. Angel Leon, said. That’s because of the relatively small number of pacemakers implanted and because the degradation that can occur does so gradually, allowing patients more time to seek help.

Dr. Leon also said he expects more warnings from medical-device manufacturers including Guidant, as the companies respond to criticism that they’ve withheld safety information.

“Every manufacturer of these devices has had failures, has had recalls, and has had advisories,” he said. “It will continue to happen. It’s how the companies handle the recalls that’s important.”

Guidant said that it would replace the pacemakers at no charge through the end of the year, even though the warranty on many has expired, and that it would reimburse patients up to $2,500 for medical expenses.

The company, which has faced a barrage of criticism from patients and physicians on its handling of the recalls and warnings, also said in its statement yesterday that it planned to set up an “independent panel of experts to recommend guidelines for when to disseminate information” on its devices.

Shares of the company fell $1.11 to $68.30 in midday trading on the New York Stock Exchange; they have traded in a 52-week range of $49.95 to $75.15. On June 24, following the second of two recalls, shares sank 6.9%, or $4.70, to $63.90.

Those levels compare with $76 a share offer from Johnson & Johnson, which Guidant shareholders voted to accept in April. The $25.4 billion cash-and-stock-deal is still pending.