Vice President Dick Cheney is being treated for a blood clot in his leg. The condition can allow the clot to break loose and cause a heart attack. It's often associated with extensive travel, where people don't get to stretch their legs. The Vice President just returned from a 25,000 mile trip.
In case you're wondering, Mr Cheney is being treated by a doctor at George Washington University. He won't be checking into Walter Reed. (SFGate)