An apparatus comprising a first tissue anchor for use with an anchor driver the first anchor comprising: a tissue-engaging element defining a central longitudinal axis of the anchor, having a sharpened distal tip, and configured to be driven into tissue of a subject; and a head, coupled to a proximal end of the tissue-engaging element, the head comprising: a driver interface, configured to be reversibly engaged by the anchor driver, and an eyelet: defining an aperture on an aperture plane, disposed laterally from the central longitudinal axis, and wherein: the apparatus comprises a delivery tool that comprises the anchor driver and a percutaneously-advanceable tube, and while the anchor driver is engaged with the first anchor, the anchor driver and the first anchor are slidable through the tube, characterised in that the aperture has a length along a long axis of the aperture and a width along a short axis of the aperture, the long axis and the short axis disposed on the aperture plane, and the length being orthogonal to the width and greater than the width, and the eyelet mounted such that the aperture plane is slanted at a fixed angle with respect to the central longitudinal axis. the first anchor comprising: a tissue-engaging element defining a central longitudinal axis of the anchor, having a sharpened distal tip, and configured to be driven into tissue of a subject; and a head, coupled to a proximal end of the tissue-engaging element, a tissue-engaging element defining a central longitudinal axis of the anchor, having a sharpened distal tip, and configured to be driven into tissue of a subject; and a head, coupled to a proximal end of the tissue-engaging element, the head comprising: a driver interface, configured to be reversibly engaged by the anchor driver, and an eyelet: defining an aperture on an aperture plane, disposed laterally from the central longitudinal axis, and wherein: the apparatus comprises a delivery tool that comprises the anchor driver and a percutaneously-advanceable tube, and while the anchor driver is engaged with the first anchor, the anchor driver and the first anchor are slidable through the tube, characterised in that the aperture has a length along a long axis of the aperture and a width along a short axis of the aperture, the long axis and the short axis disposed on the aperture plane, and the length being orthogonal to the width and greater than the width, and the eyelet mounted such that the aperture plane is slanted at a fixed angle with respect to the central longitudinal axis. a driver interface, configured to be reversibly engaged by the anchor driver, and an eyelet: defining an aperture on an aperture plane, disposed laterally from the central longitudinal axis, and wherein: the apparatus comprises a delivery tool that comprises the anchor driver and a percutaneously-advanceable tube, and while the anchor driver is engaged with the first anchor, the anchor driver and the first anchor are slidable through the tube, characterised in that the aperture has a length along a long axis of the aperture and a width along a short axis of the aperture, the long axis and the short axis disposed on the aperture plane, and the length being orthogonal to the width and greater than the width, and the eyelet mounted such that the aperture plane is slanted at a fixed angle with respect to the central longitudinal axis. defining an aperture on an aperture plane, disposed laterally from the central longitudinal axis, and wherein: the apparatus comprises a delivery tool that comprises the anchor driver and a percutaneously-advanceable tube, and while the anchor driver is engaged with the first anchor, the anchor driver and the first anchor are slidable through the tube, characterised in that the aperture has a length along a long axis of the aperture and a width along a short axis of the aperture, the long axis and the short axis disposed on the aperture plane, and the length being orthogonal to the width and greater than the width, and the eyelet mounted such that the aperture plane is slanted at a fixed angle with respect to the central longitudinal axis. the apparatus comprises a delivery tool that comprises the anchor driver and a percutaneously-advanceable tube, and while the anchor driver is engaged with the first anchor, the anchor driver and the first anchor are slidable through the tube, characterised in that the aperture has a length along a long axis of the aperture and a width along a short axis of the aperture, the long axis and the short axis disposed on the aperture plane, and the length being orthogonal to the width and greater than the width, and the eyelet mounted such that the aperture plane is slanted at a fixed angle with respect to the central longitudinal axis.