Medtronic Inc., the world's largest maker of medical devices, has agreed to pay $23.5 million to settle allegations that it paid kickbacks to doctors to implant its pacemakers and defibrillators, the U.S. Justice Department said Monday. The government alleged that Medtronic caused false claims to be submitted to Medicare and Medicaid by using two post-market studies and two device registries as vehicles to pay illegal kickbacks to doctors. Each of the studies and registries required a new or previous implant of a Medtronic device in each patient. In each case, Medtronic paid doctors a fee ranging from about $1,000 to $2,000 per patient.