WASHINGTON, Sept. 24 (Xinhuanet) -- US Vice President Dick Cheney had successful surgery Saturday to treat aneurysms behind both knees, his spokeswoman Jennifer Mayfield said.

    "Presently, the vice president is awake, alert, and comfortable" after the six-hour procedure at the George Washington University Hospital, Mayfield said in a statement.

    She said Cheney would remain in the hospital for up to 48 hoursto monitor his recovery and was expected to resume his regular schedule when released.

    Cheney's office announced last week that he would undergo an elective surgical procedure to treat an aneurysm in the artery behind the right knee that was discovered earlier this year duringa routine checkup, but it did not mention the aneurysm behind his left knee.

    Local anesthesia was used in the procedure, and there were no complications, she said.

    Cheney, 64, who has a history of heart trouble, underwent angioplasty in November 2000 after suffering his fourth heart attack since 1978.

    An aneurism is a bulging weak spot in an artery, which may eventually burst or rupture if not treated. Enditem