How is a heart valve successfully replaced?

Two ways. In the past, this is done with open heart surgery and the old valve is cut out and a new one sewn in to replace it. A new technique for the aortic valve involves crushing the old valve by blowing up a balloon and then placing the new valve through an artery in the leg, just as is done with a coronary artery stent. The procedure has been used successfully in high risk patients for surgery.
Major surgery. The patient is placed under general anestheia. A sternotomy or lateral incision is made. Cardiopulmonary bypass is instituted. Cardioplegic cardiac arrest is instituted. The old valve is excised. The new valve is sewn into place. The heart is warmed and restarted. Intraoperative esophageal echo is used to confirm normal function. The chest is closed and the pt is taken to an icu.