Former first lady Barbara Bush had open-heart surgery Wednesday and is resting comfortably at a Houston hospital with her husband, former President George H.W. Bush, by her side, Bush spokesman Jim McGrath told ABC News.
"I am very impressed with and grateful to the wonderful team of doctors and nurses at Methodist Hospital who have helped Barbara," ex-President Bush said in a prepared statement. "We have every confidence she is in the best hands."
The former president's chief of staff, Jean Becker, described Mrs. Bush, 83, as "alert and funny" after the surgery.
The surgery, which Methodist Hospital in Houston said was scheduled last week, was taken as a precautionary step after doctors found hardening on one part of Bush's aorta, McGrath said. Doctors had tracked the hardening and determined they didn't want to wait.
Bush also had some shortness of breath, another factor in the decision to perform surgery, McGrath said.
The surgery by Dr. Gerald Lawrie, heart surgeon at the Methodist DeBakey Heart & Vascular Center, lasted two-and-a-half hours, the hospital said in a statement, and involved "replacing her aortic valve with a biologic valve."
Bush should be discharged in seven to 10 days, the hospital said.
"The surgery went extremely well and we were able to successfully replace her aortic valve," Lawrie was quoted as saying in the hospital's statement. "I expect her to recover fully and soon resume her normal activities."
The rest of the Bush family was notified of the surgery, McGrath said, adding that Barbara Bush almost didn't want the younger family members told because she "didn't think it was a big deal."
But according to the hospital statement, "a hardened aortic valve needs to be replaced because, when left untreated, it can result in heart failure or sudden cardiac death."
In November, Bush underwent abdominal surgery at Houston's Methodist Hospital for an ulcer -- a procedure the hospital said was unrelated to the heart surgery.
Bush has sought medical attention in the past for a number of other issues, as well. In 1989, a thyroid condition known as Graves disease reportedly caused her to lose 18 pounds in three months.
She later began taking medication and, in 1990, received radiation therapy for her eyes as part of her treatment for this condition.
Earlier, she had received steroids to treat the condition, though her doctor later pulled her off the medication. Long-term use of steroids has been linked to the development of stomach ulcers.
ABC News' Dan Childs contributed to this report.