Abstract: Apparatus and methods for controlling blood flow through an aortopulmonary graft subsequent to completion of a first stage operation to palliate hypoplastic left heart syndrome and other cardiac abnormalities are provided, wherein an implantable cuff is applied to the graft, the cuff including an expandable element that is selectively actuated to cause constriction of the graft during diastole, responsive to detected cardiac activity, to reduce diastolic pulmonary runoff.