WASHINGTON (AP) — The Justice Department has reached settlements totaling more than $250 million with hundreds of hospitals where doctors implanted cardiac devices in violation of Medicare coverage requirements.

The settlements announced Friday encompass nearly 500 hospitals in 43 states where cardioverter defibrillators were implanted in Medicare patients too soon after they suffered a heart attack, had heart bypass surgery or angioplasty. Medicare sets waiting periods of up to 90 days before implanting the $25,000 devices, which deliver mild electric shocks to restore a normal heart rhythm.

The settlements are the result of a federal whistleblower lawsuit filed in Florida by a cardiac nurse and a health care reimbursement consultant. Under the False Claims Act, the whistleblowers will keep about $38 million from the settlements.

The Justice Department is investigating additional hospitals.