Stent with Tether Interfaces

Abstract

A radially-expandable stent is shaped so as to define a plurality of tether interfaces, a plurality of lower-securement portions, and a plurality of higher-securement portions. The lower-securement portions extend (a) along at least respective contiguous lower-securement axial segments of the stent and (b) circumferentially around respective contiguous lower-securement circumferential portions of the stent, which lower-securement axial segments and lower-securement circumferential portions include one or more of the tether interfaces. The higher-securement portions extend (a) along at least respective contiguous higher-securement axial segments of the stent and (b) circumferentially around respective higher-securement circumferential portions of the stent, collectively at all circumferential locations other than those of the lower-securement circumferential portions. The lower- and the higher-securement portions alternate around the stent. The stent is shaped so as to define a plurality of outward protrusions at respective circumferential locations around the higher-securement portions, and not around the lower-securement portions.

1 - 32 . (canceled) 
     
     
         33 . Apparatus for use with a plurality of tissue anchors and a plurality of tethers, the apparatus comprising:
 a radially-expandable stent, which, when unconstrained in a radially-expanded state, is generally tubular and shaped so as to define:
 a plurality of tether interfaces at a plurality of tether circumferential locations, respectively, each of which tether interfaces extends circumferentially contiguously around a portion of a circumference of the stent, 
 a plurality of lower-securement portions that extend (a) along at least respective contiguous lower-securement axial segments of the stent and (b) circumferentially around respective contiguous lower-securement circumferential portions of the stent, wherein (i) each of the lower-securement axial segments includes one or more of the tether interfaces, (ii) each of the lower-securement circumferential portions includes one or more of the tether interfaces, and (iii) the lower-securement circumferential portions have respective circumferential arcs, 
 a plurality of higher-securement portions that extend (a) along at least respective contiguous higher-securement axial segments of the stent and (b) circumferentially around respective higher-securement circumferential portions of the stent, collectively at all circumferential locations other than those of the lower-securement circumferential portions, wherein the lower- and the higher-securement portions alternate around the stent, and 
 a plurality of outward protrusions at respective circumferential locations around the higher-securement portions, and not around the lower-securement portions, such that each of the higher-securement portions includes one or more of the outward protrusions. 
   
     
     
         34 . The apparatus according to  claim 33 , wherein the circumferential arcs of the lower-securement circumferential portions are equal to one another. 
     
     
         35 . The apparatus according to  claim 33 , wherein the higher-securement circumferential portions have respective circumferential arcs that are equal to one another. 
     
     
         36 . The apparatus according to  claim 33 , wherein the circumferential arcs of the lower-securement circumferential portions are equal to one another, and wherein the higher-securement circumferential portions have respective circumferential arcs that are equal to one another. 
     
     
         37 . The apparatus according to  claim 65 , wherein the stent is shaped so as to define a plurality of tension-distributing elements, which (a) extend along at least respective tension-distribution axial segments of the stent at the tether circumferential locations, respectively, (b) define the tether interfaces, respectively, and (c) are configured to distribute tension applied by the tethers, respectively, along the tension-distribution axial segments of the stent, respectively. 
     
     
         38 . The apparatus according to  claim 37 , wherein the tension-distribution axial segments axially coincide with the lower-securement axial segments, respectively. 
     
     
         39 . The apparatus according to  claim 37 , wherein the tension-distributing elements and the stent are fabricated from a single unit. 
     
     
         40 . The apparatus according to  claim 37 , wherein each of the tension-distributing elements has a circumferential arc of between 1 and 15 degrees, when the stent is unconstrained in the radially-expanded state. 
     
     
         41 . The apparatus according to  claim 37 , wherein an axial length of each of the tension-distributing elements equals at least 15% of an axial length of the stent. 
     
     
         42 . (canceled) 
     
     
         43 . The apparatus according to  claim 33 , wherein the lower-securement axial segment of the stent extends along at least 30% of an axial length of the stent, when the stent is unconstrained in the radially-expanded state. 
     
     
         44 . (canceled) 
     
     
         45 . The apparatus according to  claim 33 , wherein an interior of the stent defines a right circular cylindrical shape having a radius, and wherein the outward protrusions extend radially outward from the cylindrical shape by a distance equal to between 5% and 25% of the radius, when the stent is unconstrained in the radially-expanded state. 
     
     
         46 . The apparatus according to  claim 65 , wherein the tether interfaces are shaped so as to define respective one or more openings through which the tethers are respectively coupled. 
     
     
         47 - 50 . (canceled) 
     
     
         51 . The apparatus according to  claim 33 , wherein the stent, when unconstrained in the radially-expanded state, is shaped so as to define a same number of the tether interfaces and the lower-securement portions. 
     
     
         52 . The apparatus according to  claim 51 , wherein the tether circumferential locations are circumferentially centered in the lower-securement portions, respectively. 
     
     
         53 . The apparatus according to  claim 33 , wherein the outward protrusions are rotationally-asymmetrically distributed around the circumference of the stent, when the stent is unconstrained in the radially-expanded state. 
     
     
         54 . The apparatus according to  claim 33 , wherein the outward protrusions are periodically distributed around each of the higher-securement circumferential portions, when the stent is unconstrained in the radially-expanded state. 
     
     
         55 - 56 . (canceled) 
     
     
         57 . The apparatus according to  claim 33 , wherein each of the circumferential arcs of the lower-securement circumferential portions equals at least 200% of an average of circumferential distances between circumferential midpoints of circumferentially-adjacent ones of the outward protrusions around the higher-securement portions, when the stent is unconstrained in the radially-expanded state. 
     
     
         58 . The apparatus according to  claim 33 ,
 wherein the stent comprises a plurality of columnar struts and a plurality of circumferential stent meanders coupled to the columnar struts at respective axial locations, and   wherein one or more of the circumferential stent meanders are shaped so as to define the outward protrusions at the respective circumferential locations around the higher-securement portions, when the stent is unconstrained in the radially-expanded state.   
     
     
         59 . The apparatus according to  claim 58 , wherein, when the stent is unconstrained in the radially-expanded state, at least one of the circumferential stent meanders is shaped so as to define (a) around the higher-securement portions, the outward protrusions, and (b) around the lower-securement portions, respective arcs of a circle if the circumferential stent meander is projected onto a plane perpendicular to a longitudinal axis of the stent. 
     
     
         60 - 62 . (canceled) 
     
     
         63 . The apparatus according to  claim 33 , wherein each of the tether interfaces extends circumferentially contiguously around less than 30 degrees of the circumference of the stent. 
     
     
         64 . The apparatus according to  claim 33 , wherein the apparatus further comprises the plurality of tissue anchors. 
     
     
         65 . The apparatus according to  claim 33 , wherein the apparatus further comprises the plurality of tethers, which have respective first longitudinal portions that are coupled to the plurality of tether interfaces, respectively. 
     
     
         66 . The apparatus according to  claim 65 , wherein the apparatus further comprises the plurality of tissue anchors, and wherein the plurality of tethers have respective second longitudinal portions, different from the respective first longitudinal portions, that are coupled the plurality of tissue anchors, respectively. 
     
     
         67 . The apparatus according to  claim 33 , wherein each of the respective circumferential arcs of the lower-securement circumferential portions is between 30 and 90 degrees.