A method of replacing the function of a native heart valve is achieved by inserting a distal end portion of a delivery apparatus into a patient's body, wherein a prosthetic valve is disposed along the distal end portion of the delivery apparatus. The prosthetic valve includes a collapsible and expandable annular body having a network of struts interconnected at a plurality of nodes to form a plurality of open cells. Atrial and ventricular flanges are coupled to the annular body and extend radially away from the annular body. The annular body includes three commissure support posts of fixed length that extend substantially the entire length of the annular body. A valve member is secured to the commissure support posts. The annular body is radially expanded within the native heart valve and the atrial and ventricular flanges are deployed on opposite sides of the native heart valve.