More than a thousand malfunction incidents involving Medtronic pacemaker defibrillator wires were reported this year before the company pulled the items from the market, a consumer advocacy group says.

Minneapolis-based Medtronic Inc. on Monday withdrew the lead wires for fracture problems that may be linked to five U.S. deaths.

But Dr. Sidney Wolfe, director of the health research group at Public Citizen, says the company waited too long.

Some 1,194 associated injuries had been reported — up from 296 injury reported in the first 10 months of 2006, according toWolfe's letter to the U.S. Food and Drug Administration.

"Why did the FDA, aware of the rapidly mounting number of injury reports, not force the company to recall defibrillators not yet implanted in the early part of this year?" he wrote Dr. Sidney Wolfe.

The company said the problems may cause unnecessary shocks or cause the unit to fail.

More than 268,000 leads curently are in use, including about 6,000 in Canada.

The action applies to Medtronic's Sprint Fidelis models 6930, 6931, 6948 and 6949.

FDA officials defended their response to the problem, saying there was no indication of a specific problem with the Medtronic brand.

"Once the needle in the haystack has been pointed out to people, it seems like it's obvious to see," said FDA's Megan Moynahan, who led monitoring of the device.

Medtronic also said it withdrew the wires as quickly as possible after gathering "appropriate" information.

The company urged doctors in March to exercise care when implanting the leads.

The FDA, Medtronic and the U.S. Heart Rhythm Society do not recommend removing fractured leads because of associated risks.

The company says it can reprogram the units.

With files from the Associated Press