A frame assembly (222) includes a tubular portion (32) that defines a lumenalong an axis, a plurality of anus (46)coupled to the tubular portion at a first axial level, each of the armsextending radially outward from the tubular portion to a respectivearm- tip, and a plurality of ventricular legs (50) that are coupled to thetubular portion at a second axial level, and that extend radiallyoutward from the tubular portion. A first sheet (440) has a greater perimeter(446), and a smaller perimeter (448) that defines an opening.The first sheet is stitched onto the plurality of arms, with the openingaligned with the lumen. Subsequently, an outer perimeter (454)of a second sheet (450) is stitched to the greater perimeter of the firstsheet Subsequently, the second sheet is everted by passing aninner perimeter (452) of the second sheet around the arm-tips
