Apparatus for delivery through a cardiac tissue wall in a constrained state within a deployment tool , the apparatus comprising a tissue anchor , which comprises: an anchor shaft having a central longitudinal axis ; a tissue-coupling element , configured to have a predetermined shape when unconstrained by the deployment tool and automatically transition to the predetermined shape when released from being constrained by the deployment tool , and which (a) extends from a distal end of the anchor shaft , and (b) comprises a wire , wherein when the tissue anchor is unconstrained by the deployment tool : (a) the wire is shaped as an open shape , and (b) if the tissue-coupling element were to be projected onto a plane that is perpendicular to the central longitudinal axis , the projection of the open shape would surround between 170 and 355 degrees of a point in the plane ; and a flexible elongate tension member , which includes (a) a distal portion that is fixed to a site on the wire , (b) a proximal portion , which has a longitudinal segment that runs alongside at least a portion of the anchor shaft , and (c) a crossing portion , which (i) is disposed between the distal and the proximal portions along the flexible elongate tension member , and (ii) crosses at least a portion of the open shape when the tissue anchor is unconstrained by the deployment tool , wherein the tissue anchor is configured to allow relative axial motion between the at least a portion of the anchor shaft and the longitudinal segment of the proximal portion of the flexible elongate tension member when the tissue anchor is unconstrained by the deployment tool , wherein the point falls on a projection onto the plane of a line segment that terminates at (a) the site on the wire and (b) a proximal end of the wire when the tissue anchor is unconstrained by the deployment tool . an anchor shaft having a central longitudinal axis ; a tissue-coupling element , configured to have a predetermined shape when unconstrained by the deployment tool and automatically transition to the predetermined shape when released from being constrained by the deployment tool , and which (a) extends from a distal end of the anchor shaft , and (b) comprises a wire , wherein when the tissue anchor is unconstrained by the deployment tool : (a) the wire is shaped as an open shape , and (b) if the tissue-coupling element were to be projected onto a plane that is perpendicular to the central longitudinal axis , the projection of the open shape would surround between 170 and 355 degrees of a point in the plane ; and a flexible elongate tension member , which includes (a) a distal portion that is fixed to a site on the wire , (b) a proximal portion , which has a longitudinal segment that runs alongside at least a portion of the anchor shaft , and (c) a crossing portion , which (i) is disposed between the distal and the proximal portions along the flexible elongate tension member , and (ii) crosses at least a portion of the open shape when the tissue anchor is unconstrained by the deployment tool , wherein the tissue anchor is configured to allow relative axial motion between the at least a portion of the anchor shaft and the longitudinal segment of the proximal portion of the flexible elongate tension member when the tissue anchor is unconstrained by the deployment tool , wherein the point falls on a projection onto the plane of a line segment that terminates at (a) the site on the wire and (b) a proximal end of the wire when the tissue anchor is unconstrained by the deployment tool . <EOS>