An anchor of an implant is transluminally advanced to a heart of a subject, the anchor including a distal helical element, and a post extending proximally from the distal helical element. The implant is anchored to tissue of the heart by driving the distal helical element into tissue of the heart, and compressing a fabric tube against the tissue by moving an annular member, coupled to the post, toward the tissue such that the fabric tube becomes sandwiched between the annular member and the tissue. Other embodiments are also described.