A medical equipment company pleaded guilty to selling thousands of defective pacemakers to doctors, knowing the devices could stop working without warning, and four executives were charged with the cover-up.

The officers of the Cordis Corp. ignored internal memos urging that doctors be informed about the defects and sent false statements to the Food and Drug Administration to conceal the problems, according to federal indictments.Cordis, a Miami-based company that has since sold its heart pacemaker division, pleaded guilty to concealing the defects in federal court in a related action. The company said the plea covers only Cordis and not its officers at the time.