Updated

Surgeons successfully removed fluid and scar tissue from Bill Clinton's chest cavity Thursday, cleaning up complications from the former president's heart bypass operation of six months ago.

Clinton was "awake and resting comfortably" after four hours of surgery, said Herbert Pardes, president of New York-Presbyterian Hospital/Columbia University Medical Center (search). "We expect Mr. Clinton to be walking" within 24 hours.

His wife, Sen. Hillary Rodham Clinton (search), and daughter, Chelsea, were with him and were said to be elated by the successful surgery and a prognosis from one of his surgeons for an "even better than a full recovery."

Pardes said Clinton, 58, was expected to spend three to 10 more days in the hospital. A tube to drain fluid from the left lung will be removed in two to five days.

In a rare complication from his bypass surgery in September, scar tissue had developed because of fluid buildup and inflammation, causing compression and the collapse of the lower lobe of Clinton's left lung.

Surgeons removed a thick rind of scar tissue, in some places up to 8 millimeters (0.3 inches) thick, which made it impossible to use a minimally invasive videoscopy. Instead, surgeons performed more traditional surgery.

"It was like peeling an orange," said Dr. Joshua Sonett, one of the surgeons, about removing the tissue.

By the end of the operation, Clinton's lung "was very healthy and looked excellent," he said. "We expect even better than a full recovery."

The operation was done at the same facility where Clinton underwent open-heart surgery. Doctors described it as a low-risk procedure, and Clinton himself called it routine.

Still, such problems crop up in only a faction of 1 percent of bypass cases; doctors said the combination of fluid and scar tissue had decreased Clinton's left lung capacity by 25 percent. The former president first noticed the problem when he suffered shortness of breath during his daily 4-mile walk.

The surgery began at 7 a.m., about two hours after Clinton arrived in an SUV at the Manhattan hospital on a brisk winter morning.

The Secret Service, police and hospital security staff conducted a sweep of the walkways and corridors as Clinton was whisked inside through a side entrance before the operation. He arrived in an SUV that pulled inside a hospital gate, providing quick access inside.

The former president had been in Florida on Wednesday at a charity golf tournament to benefit tsunami victims. He appeared relaxed, cracking jokes about his golf game and saying he wasn't worried about the surgery.

More than 1,000 people sent the 42nd president good wishes through his Web site.

Across the street from the hospital, good wishes and prayers for Clinton were offered at a restaurant named El Presidente. "I pray to God that he is well, that he comes out healthy," said manager Wilton Rafael Marte Fermin.

The Clintons asked well-wishers to make donations to the American Heart Association (search), which set up a special location for such contributions on its web site.

Since his heart surgery, Clinton has presided over the opening of his presidential library in Little Rock, Ark., and joined former President Bush for a public relations campaign to help raise money for the Asian tsunami victims.