Apparatuses and methods are disclosed for performing a procedure on a heart valve in which a loop of material contacts at least a portion of the annulus or the leaflets of a valve. Anchors are distributed about the loop and configured for implantation into the annulus or the leaflets in a forward direction and resist extraction in a backwards direction. The anchors each have a pointy front end and a back end, and two panels of material with cylindrically curved outer surfaces. A slot runs in a front-to-back direction between the two panels of material. After the anchors are implanted into the annulus or the leaflets, the loop can be used to retain a replacement valve or to constrict the annulus.
