Unconfirmed media reports say Nancy Guthrie's pacemaker stopped syncing with her Apple devices. Here's what that means.

Nancy Guthrie, 84, had been missing for four days after authorities believed she was taken from her Arizona home. Her medication and stopped pacemaker connection raised concerns about her health and safety.

When Aurora Ernzen was just 5 days old, doctors performed surgery to insert a pacemaker in her chest. The device was new, permitted through emergency use guidelines from the U.S. Food and Drug Administration. About the size of a triple-A battery ...