Via Huffington Post:

Vice President Dick Cheney was taken to the cardiac unit of the Vail Valley Medical Center Friday. Contrary to Associated Press reports that he went to see orthopedic surgeon, Dr. Steadman, for a knee injury, Vice President Cheney passed through the orthopedic center directly to the cardiac unit to see Dr. Jack Eck and his team. The Vice President checked into the hospital under the name of Dr. Hoffman.

Arianna is also in Vail and has more details. This AP article just mentions Cheney going to get his old knee injury checked.