An implant delivery system for delivering one or more tissue anchors coupled together by a tether, the system comprising: a catheter comprising a longitudinal axis, a first elongate element lumen, a second elongate element lumen, and a tissue anchor lumen for receiving the one or more tissue anchors and the tether, wherein first elongate element apertures extend along the longitudinal axis and open into the first elongate element lumen, second elongate element apertures extend along the longitudinal axis and open into the second elongate element lumen, and tissue anchor apertures open into the tissue anchor lumen, and the catheter further comprising a plurality of retaining portions each between adjacent tissue anchor apertures, wherein the retaining portions each comprise a channel along the longitudinal axis, the channels having a locked, closed configuration wherein the tether is retained in the tissue anchor lumen and an unlocked, open configuration wherein the tether is releasable from the tissue anchor lumen by passing through the channel; a first elongate element within the first elongate element lumen; and a second elongate element within the second elongate element lumen, wherein for each pair of adjacent first and second elongate element apertures, when the first elongate element extends out of the first elongate element lumen through the first elongate element aperture across the retaining portion transversely with respect to the longitudinal axis and towards the second elongate element aperture into the second elongate element lumen, loops over the second elongate element, and extends out of the second elongate element aperture back across the retaining portion and into the first elongate element lumen the channels are in the locked configuration and when the second elongate element is retracted proximally from the second elongate element lumen the first elongate element is uncoupled from the second elongate element and the channels are in the unlocked configuration. a catheter comprising a longitudinal axis, a first elongate element lumen, a second elongate element lumen, and a tissue anchor lumen for receiving the one or more tissue anchors and the tether, wherein first elongate element apertures extend along the longitudinal axis and open into the first elongate element lumen, second elongate element apertures extend along the longitudinal axis and open into the second elongate element lumen, and tissue anchor apertures open into the tissue anchor lumen, and the catheter further comprising a plurality of retaining portions each between adjacent tissue anchor apertures, wherein the retaining portions each comprise a channel along the longitudinal axis, the channels having a locked, closed configuration wherein the tether is retained in the tissue anchor lumen and an unlocked, open configuration wherein the tether is releasable from the tissue anchor lumen by passing through the channel; a first elongate element within the first elongate element lumen; and a second elongate element within the second elongate element lumen, wherein for each pair of adjacent first and second elongate element apertures, when the first elongate element extends out of the first elongate element lumen through the first elongate element aperture across the retaining portion transversely with respect to the longitudinal axis and towards the second elongate element aperture into the second elongate element lumen, loops over the second elongate element, and extends out of the second elongate element aperture back across the retaining portion and into the first elongate element lumen the channels are in the locked configuration and when the second elongate element is retracted proximally from the second elongate element lumen the first elongate element is uncoupled from the second elongate element and the channels are in the unlocked configuration.