Spokesman Jim McGrath says the surgery at The Methodist Hospital on Wednesday lasted about 2½ hours and was scheduled last week after Bush experienced a shortness of breath.
He says doctors determined the aortic valve had started to harden.
The hospital said in a statement that Dr Gerald Lawrie, a heart surgeon at the Methodist DeBakey Heart & Vascular Center, replaced the valve with a biologic valve, which is made of natural living tissue.
Lawrie said the surgery went “extremely well” and that he expects Bush to recover fully and soon resume her normal activities.
Former President George HW Bush was at the hospital with his wife.