Apparatus for delivery through tissue in a constrained state within a deployment tool (30), the apparatus comprising a tissue anchor (120), which comprises: a shaft (122), which comprises a sealing element (190)； a head (124) connected to a proximal portion (126) of the shaft (122)； and a tissue-coupling element (128), which extends from a distal end (130) of the shaft (122), wherein, when the tissue anchor (120) is unconstrained by the deployment tool (30): the shaft (122) has a central longitudinal axis (134), the head (124) is coaxial with the central longitudinal axis (134), and the tissue-coupling element (128) is shaped such that if the tissue-coupling element (128) were to be projected onto a plane (136) that is perpendicular to the central longitudinal axis (134), (a) at least 80% of an area (138) of a projection (139) of the tissue-coupling element (128) on the plane (136) would fall within a first angle (α) of 180 degrees in the plane (136) having a vertex (140) at the central longitudinal axis (134), and (b) the area (138) would partially overlap, at least 3 mm from the vertex (140), both rays (142A, 142B) of a second angle (β) of between 45 and 180 degrees in the plane (136) having the vertex (140) at the central longitudinal axis (134).
