Apparatus, comprising: a tissue-engaging element (50, 54) having a distal portion configured to engage at least a first portion of tissue of a patient, and having a proximal portion; an implant (36, 42) comprising: a rotatable structure; at least one flexible longitudinal member having a first portion thereof that is in contact with the rotatable structure, and a second portion thereof that is configured to be coupled to a second portion of tissue of the patient, wherein, during rotation of the rotatable structure in a first rotational direction, successive portions of the flexible longitudinal member advance in a first advancement direction with respect to the rotatable structure and contact the rotatable structure, and, pull the second portion of the flexible longitudinal member toward the implant (36, 42), and responsively, to draw the first and second portions of tissue toward each other; characterized by at least one docking station coupled to the proximal portion of the tissue-engaging element (50, 54), the at least one docking station being configured to be coupled to the implant (36, 42); and at least one guide member reversibly coupled to the at least one docking station, the at least one guide member being configured for facilitating slidable advancement of the at least one implant (36, 42) toward the tissue-engaging element (50, 54). a tissue-engaging element (50, 54) having a distal portion configured to engage at least a first portion of tissue of a patient, and having a proximal portion; an implant (36, 42) comprising: a rotatable structure; at least one flexible longitudinal member having a first portion thereof that is in contact with the rotatable structure, and a second portion thereof that is configured to be coupled to a second portion of tissue of the patient, wherein, during rotation of the rotatable structure in a first rotational direction, successive portions of the flexible longitudinal member advance in a first advancement direction with respect to the rotatable structure and contact the rotatable structure, and, pull the second portion of the flexible longitudinal member toward the implant (36, 42), and responsively, to draw the first and second portions of tissue toward each other; characterized by at least one docking station coupled to the proximal portion of the tissue-engaging element (50, 54), the at least one docking station being configured to be coupled to the implant (36, 42); and at least one guide member reversibly coupled to the at least one docking station, the at least one guide member being configured for facilitating slidable advancement of the at least one implant (36, 42) toward the tissue-engaging element (50, 54). at least one flexible longitudinal member having a first portion thereof that is in contact with the rotatable structure, and a second portion thereof that is configured to be coupled to a second portion of tissue of the patient, wherein, during rotation of the rotatable structure in a first rotational direction, successive portions of the flexible longitudinal member advance in a first advancement direction with respect to the rotatable structure and contact the rotatable structure, and, pull the second portion of the flexible longitudinal member toward the implant (36, 42), and responsively, to draw the first and second portions of tissue toward each other; characterized by at least one docking station coupled to the proximal portion of the tissue-engaging element (50, 54), the at least one docking station being configured to be coupled to the implant (36, 42); and at least one guide member reversibly coupled to the at least one docking station, the at least one guide member being configured for facilitating slidable advancement of the at least one implant (36, 42) toward the tissue-engaging element (50, 54).