President George H.W. Bush through the years

Former President George Bush, right, answers questions about his heart condition as cardiologist Mark Hausknecht laughs during a news conference at Methodist Hospital on Friday, Feb. 25, 2000 in Houston. Bush spent Thursday night in a Florida hospital and was released Friday after being treated for an irregular heartbeat. Doctors will investigate whether Bush's thyroid disorder, called Graves' disease, caused the irregularity. It was responsible for a similar episode he suffered while jogging in May 1991.  <span class=meta>(AP Photo/ DAVID J. PHILLIP)</span>
December 28, 2012 9:29:18 AM PST