Fastener for holding a constricting cord in a reduced-diameter state around a cardiac valve annulus, and installation of the fastener

An apparatus for fastening a cord that has been affixed around an annulus, the apparatus comprising:

• a housing having an upper wall and a lower wall, with a channel disposed between the upper wall and the lower wall, the channel having a distal end;
• a sliding member situated at an initial position with respect to the housing with a portion of the sliding member disposed within the channel, the sliding member having an upper surface and a lower surface, wherein the sliding member has an opening that runs between the upper surface and the lower surface, the opening having a distal end, and wherein at least a portion of the opening with an area of at least 0.4 mm2 extends distally beyond the distal end of the channel;
• and
• a first shear pin arranged to hold the sliding member at the initial position until the first shear pin is sheared by a force that exceeds a first threshold,
• wherein the sliding member and the housing are configured so that (a) subsequent to shearing of the first shear pin, the sliding member will be free to slide in a proximal direction with respect to the housing until the sliding member reaches a final position and (b) upon reaching the final position, the sliding member will be immobilized at the final position, wherein the sliding member and the housing are shaped and dimensioned so that after the sliding member has been moved to the final position, the distal end of the opening in the sliding member will be at least 0.1 mm away, in a proximal direction, from the distal end of the channel, and
• wherein the upper wall of the housing and the lower wall of the housing are spaced apart by a first distance, wherein the upper surface of the sliding member and the lower surface of the sliding member are spaced apart by a second distance, and wherein the first distance exceeds the second distance by between 40 and 140 μm.

An apparatus for fastening a cord that has been affixed around an annulus, the cord having a nominal diameter D, the apparatus comprising:

• a housing having an upper wall and a lower wall, with a channel disposed between the upper wall and the lower wall, the channel having a distal end;
• a sliding member situated at an initial position with respect to the housing with a portion of the sliding member disposed within the channel, the sliding member having an upper surface and a lower surface, wherein the sliding member has an opening that runs between the upper surface and the lower surface, the opening having a distal end, and wherein at least a portion of the opening with an area of at least 10×D2 extends distally beyond the distal end of the channel;
• and
• a first shear pin arranged to hold the sliding member at the initial position until the first shear pin is sheared by a force that exceeds a first threshold,
• wherein the sliding member and the housing are configured so that (a) subsequent to shearing of the first shear pin, the sliding member will be free to slide in a proximal direction with respect to the housing until the sliding member reaches a final position and (b) upon reaching the final position, the sliding member will be immobilized at the final position, wherein the sliding member and the housing are shaped and dimensioned so that after the sliding member has been moved to the final position, the distal end of the opening in the sliding member will be at least 0.5×D away, in a proximal direction, from the distal end of the channel, and
• wherein the upper wall of the housing and the lower wall of the housing are spaced apart by a first distance, wherein the upper surface of the sliding member and the lower surface of the sliding member are spaced apart by a second distance, and wherein the first distance exceeds the second distance by between 0.25×D and 0.9×D.