A device for improving the function of a heart valve comprises a first loop-shaped support, which is configured to abut a first side of the heart valve. A first flange unit is may be configured as a fabric sleeve covering the loop-shaped support. A portion of the fabric sleeve forms a flange that is attached to the annulus when said first loop-shaped support is abutting said heart valve. The flange is provideable by folding at least a portion of said sleeve over itself for forming a double layer of opposing fabrics thereof, such that said sleeve comprises a flange portion extending from said first loop-shaped support configured to overlap a surface of, and form a collar around, at least a portion of said annulus.
