David O'Brien of the AJC (Braves beat writer) just wrote on his blog, that Giles missed today's doubleheader because of a heart-valve condition that was just discovered. O'Brien said he will probably miss a couple of weeks, though this is pending an examination in Atlanta to be sure.
http://www.ajc.com/blogs/content/shared ... ent-648794
A valve in Giles' heart may not be operating properly and he'll undergo tests with a cardiovascular specialist on Sunday. He may need to undergo a minor surgical procedure that would keep him out a week, the team's official web site reports.
He may need to undergo a procedure in which a staple is used to close the malfunctioning valve in his heart. Given the injury, expect Giles to be out more than a week if he needs surgery. Either way, put him on reserve this week.