Off-center tissue anchors

A cardiovascular tissue-anchor system comprising:

• a medical implant, which comprises a stent comprising a plurality of interconnected superelastic metallic struts, and which is configured to be deployed by radial expansion and sized to fit adjacent to cardiovascular tissue within a body of a subject at a target site;
• a tissue anchor, which is separate and distinct from the medical implant, and which comprises (a) a tissue-engaging portion configured to engage a heart wall of the subject, and (b) a tether-locking mechanism, which comprises a movable tether-securing element, wherein an outer perimeter of the tissue-engaging portion is circular;
• a braided tether, which is configured to couple to the medical implant to the tissue anchor, and to apply a desired tension between the medical implant and the tissue anchor, wherein the tissue anchor is shaped so as to define an opening through which the braided tether is disposed;
• a medical-implant-deployment tool, which (a) comprises a catheter, in which the medical implant is removably disposed in a compressed state, and (b) is configured to deliver the medical implant to the target site within the body of the subject while the medical implant is in the compressed state, and to deploy the medical implant from the catheter, thereby transitioning the medical implant to a radially-expanded state at the target site, so as to locate the superelastic metallic struts adjacent to the tissue at the target site to resist movement of the medical implant toward the tissue anchor caused by blood flow;
• and
• a torque-delivery tool, which is configured to (a) deliver the tissue anchor to the heart wall while the tether-locking mechanism is in an unlocked state, and (b) thereafter, while the desired tension is applied by the braided tether between the medical implant and the tissue anchor, transition the tether-locking mechanism to a locked state in which the movable tether-securing element engages the braided tether, thereby inhibiting sliding of the braided tether through the opening of the tissue anchor and locking the braided tether to the tissue anchor, thereby maintaining the desired tension between the medical implant and the tissue anchor,
• wherein the torque-delivery tool comprises a releasable torque-delivery shaft, the torque-delivery shaft comprising a distal torque-delivery head coaxial with the torque-delivery shaft, and having a shape suitable to engage the tissue anchor, and
• wherein the torque-delivery tool is configured to apply a rotational force to a portion of the tissue anchor via the distal torque-delivery head while the distal torque-delivery head is removably coupled to the tissue anchor.