(CNN) -- The surgeon who performed heart surgery Wednesday on former first lady Barbara Bush said Thursday that she is recovering well from the 2 1/2-hour surgery in which her aortic valve was replaced with a pig valve.
Former first lady Barbara Bush had heart surgery Wednesday in Houston, Texas.
"From our perspective, this was a very routine procedure, and we expect her to make an excellent recovery," Dr. Gerald Lawrie told reporters at Methodist DeBakey Heart & Vascular Center in Houston.
Bush had experienced "severe narrowing of the main valve that lets the blood come out of the heart into the circulation," Lawrie said.
"This valve, instead of being a soft, flexible structure that opens and closes, breaks down," he said, adding that calcium deposits cause it to stiffen, which can result in fluid in the lungs and progressive deterioration.
He said an echocardiogram showed her condition was "extremely severe."
Typical symptoms of problems with an aortic valve include shortness of breath, fatigue, weakness and swelling, he said.
Though his patient is 83, "she's a very fit lady," which helped make the operation a "relatively straightforward" procedure," he said.
Diagnosed with the condition less than a week before the surgery, Bush entered the operating room at 7 a.m. and, after an hour of preparation during which lines were attached to her and anesthesia was administered, the main work began, Lawrie said.
In all, she was on a heart-lung machine for 55 minutes; the implantation of the valve took 45 minutes, he said. She required no blood transfusion.
Bush was back in the intensive care unit by 10:45 a.m., where she awoke "quicker than most" patients of her age, he said.
He described her as "very lucid."
"She recognized all of us immediately and actually started tearing us up with some humorous comments just as soon as we took that tube out."
He predicted she would remain in the ICU until Friday or Saturday, and then be transferred to a standard hospital floor for another five to seven days. But already, he said, she is "walking around the room a little bit."
Bush's husband of 64 years, former President George H. W. Bush, visited her shortly after the operation.
"I've been a nervous wreck about it," said the former president, who said he had received telephone calls of support from President Obama and all the other surviving former presidents.
"I think there is a lot of interest because of who she is," he said, his voice cracking.
"She looks well. I just came from her room and she's doing well. I keep saying, 'You look great.' [She says] 'Don't tell me that.' But you know, she does ... she looks well to me -- and beautiful."
Bush added, "She's in command. She's in control of our whole family."
Asked to describe what occurred between the two when he saw her, he said, "I don't remember any words. I'm not the anecdotal one in the family. It was just a reunion of two people who love each other."
Afterward, the former president turned to a hospital administrator and said, "I'm sorry I get emotional, but I can't help it."
The Bush family matriarch is the mother of former President George W. Bush and former Florida Gov. Jeb Bush.