Apparatus is provided, including a tube (421) shaped to define a tube lumen at least one implant (100) reversibly coupled to the tube (421), and configured for implantation within a body of a patient. The apparatus also comprises two or more longitudinal guide members (470) disposed at least in part along a distal portion of the tube (421), the longitudinal guide members (470) having distal portions thereof configured to be reversibly coupled to the implant (100), and arranged such that application of a force to a first one of the longitudinal guide members (470) steers the distal portion of the tube (421) toward a first location along the implant (100), and application of a force to a second one of the longitudinal guide members (470) steers the distal portion of the tube (421) toward a second location along the implant (100). Other embodiments are also described.