Tennessee executed death row inmate Byron Black on Tuesday despite raised concerns about his implanted heart device, which could cause a "prolonged and torturous execution."

Byron Black, a death row inmate convicted of killing his girlfriend and her two young daughters, is scheduled to be executed this morning.

Tennessee is scheduled to execute death row inmate Byron Black on Tuesday morning despite concerns his heart implant will shock him repeatedly during the lethal injection. Black, 69, is one of the longest residents on the state's death row.