The former first lady, 83, thanked the doctors and staff at Methodist Hospital as she left with her husband, former President George H.W. Bush.
Doctors termed Mrs. Bush's condition, a severe narrowing of the main heart valve, as common in people of her age. The March 4 operation, in which the aortic valve was replaced with a valve from a pig, took about 2½ hours.
"This Friday the 13th turned out to be a very lucky one for me, because I was able to go home with George feeling healthy and strong," Mrs. Bush said in a statement.
"Nobody ever had better medical treatment than I did this past week and a half," she added.
Her husband acknowledged last week he'd been a "nervous wreck" about the surgery.
Heart surgeon Dr. Gerald Lawrie, who led the surgical team, said Mrs. Bush will have to take it easy for at least another three weeks before resuming normal activities. He called her "a remarkable patient" and said her recovery went quickly for such a procedure.
Mrs. Bush had undergone surgery in November for a perforated ulcer. Lawrie said the two ailments were unrelated and the ulcer surgery was potentially more severe.