U.S. Vice President Dick Cheney is undergoing elective surgery Saturday, to repair a damaged artery behind his right knee.
The procedure is being performed at a hospital in Washington. Senior aides say Mr. Cheney may remain hospitalized for up to 48 hours so doctors can monitor his recovery.
The surgery will treat an aneurysm, a bulging spot created by a weakness in the artery wall.
A routine physical exam earlier this year detected aneurysms behind both of Mr. Cheney's knees. He is expected to have similar surgery on his left knee in the near future.
The 64-year-old vice president has had four heart attacks. The last one occurred after the contested presidential election in 2000.