U.S. patent application number 15/891754 was filed with the patent office on 2018-07-05 for stent with tether interfaces.
This patent application is currently assigned to 4Tech Inc.. The applicant listed for this patent is 4Tech Inc.. Invention is credited to Michael Gilmore, Charlotte Murphy, Idan Tobis.
Application Number | 20180185179 15/891754 |
Document ID | / |
Family ID | 50439453 |
Filed Date | 2018-07-05 |
United States Patent
Application |
20180185179 |
Kind Code |
A1 |
Murphy; Charlotte ; et
al. |
July 5, 2018 |
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.
Inventors: |
Murphy; Charlotte;
(Ardrahan, IE) ; Tobis; Idan; (Beth Hashmonai,
IL) ; Gilmore; Michael; (Ardrahan, IE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
4Tech Inc. |
Waltham |
MA |
US |
|
|
Assignee: |
4Tech Inc.
Waltham
MA
|
Family ID: |
50439453 |
Appl. No.: |
15/891754 |
Filed: |
February 8, 2018 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
14773640 |
Sep 8, 2015 |
9907681 |
|
|
PCT/IL2014/050233 |
Mar 9, 2014 |
|
|
|
15891754 |
|
|
|
|
61783224 |
Mar 14, 2013 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2230/0069 20130101;
A61F 2/2487 20130101; A61F 2/2451 20130101; A61B 2017/0414
20130101; A61F 2002/8486 20130101; A61F 2/848 20130101; A61F
2220/0016 20130101; A61F 2/88 20130101; A61F 2/2418 20130101; A61F
2220/0008 20130101; A61B 17/0401 20130101; A61B 2017/0441
20130101 |
International
Class: |
A61F 2/88 20060101
A61F002/88; A61B 17/04 20060101 A61B017/04; A61F 2/848 20130101
A61F002/848 |
Claims
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.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a divisional of U.S. application
Ser. No. 14/773,640, filed Sep. 8, 2015, which is the U.S. national
stage of International Application PCT/IL2014/050233, filed Mar. 9,
2014, which claims priority from US Provisional Application
61/783,224, filed Mar. 14, 2013, which is assigned to the assignee
of the present application and is incorporated herein by
reference.
FIELD OF THE APPLICATION
[0002] The present invention relates generally to stents, and
specifically to stents for anchoring within body lumens.
BACKGROUND OF THE APPLICATION
[0003] Stents are used for various cardiovascular applications,
such as to keep coronary vessels open, to act as grafts in
abdominal aortic aneurisms ("AAAs"), to anchor vena cava filters,
or to act as a frame for aortic valves. Stents are generally
cylindrical, conical, or bottle shaped, and are designed to exert a
radial force towards the vessel in which they are implanted. The
resulting friction force provides securement of the stent to the
vessel, thereby preventing migration of the stent after
implantation. Techniques for increasing stent securement include
providing hooks or barbs, shaping the stent into a truncated cone,
and protruding the stent struts.
[0004] Functional tricuspid regurgitation (FTR) is governed by
several pathophysiologic abnormalities such as tricuspid valve
annular dilatation, annular shape, pulmonary hypertension, left or
right ventricle dysfunction, right ventricle geometry, and leaflet
tethering. Treatment options for FTR are primarily surgical. The
current prevalence of moderate-to-severe tricuspid regurgitation is
estimated to be 1.6 million in the United States. Of these, only
8,000 patients undergo tricuspid valve surgeries annually, most of
them in conjunction with left heart valve surgeries.
SUMMARY OF THE APPLICATION
[0005] Some applications of the present invention provide an
anchoring system, which comprises a radially-expandable stent, and
typically one or more tissue anchors and one or more tethers that
connect the stent to the one or more tissue anchors. The stent is
configured to be implanted in a body lumen, such as a blood vessel.
The stent typically lacks rotational symmetry, because some of the
struts of a circumferential portion of the stent protrude outwardly
and thereby define a polygonal shape, while the struts of another
contiguous circumferential portion of the stent do not protrude
outwardly and thereby define a cylindrical shape.
[0006] The circumferential portion with the outward protrusions
exhibits higher securement forces with the wall of the body lumen
than does the circumferential portion without the outward
protrusions, thus allowing relative axial movement of the
non-protruding circumferential portion while maintaining the stent
as a whole secured in the body lumen. Such selective securement may
relieve stresses in the stent frame resulting from cyclic loads
applied to the stent (e.g., cyclic cardiac loads) at the one or
more tether circumferential locations, thereby enabling higher
fatigue endurance in the stent.
[0007] For some applications, when unconstrained in a
radially-expanded state, the stent is generally tubular and shaped
so as to define: [0008] one or more tether interfaces at one or
more tether circumferential locations, respectively, each of which
tether interfaces extends circumferentially contiguously around
less than 30 degrees of a circumference of the stent; [0009] a
lower-securement portion that extends (a) along at least a
contiguous lower-securement axial segment of the stent and (b)
circumferentially around a contiguous lower-securement
circumferential portion of the stent, which lower-securement axial
segment and lower-securement circumferential portion include the
one or more tether interfaces; [0010] a higher-securement portion
that extends (a) along at least a contiguous higher-securement
axial segment and (b) circumferentially around a higher-securement
circumferential portion of the stent at all circumferential
locations other than those of lower-securement circumferential
portion. The higher-securement circumferential portion typically
extends around between 215 and 330 degrees of the circumference of
the stent (e.g., at least 270 degrees of the circumference); and
[0011] a plurality of outward protrusions at respective outward
circumferential locations around the higher-securement portion, and
not around the lower-securement portion.
[0012] The outward protrusions of the higher-securement portion
cause the higher-securement portion to apply greater securement
forces against the body lumen wall than applied by the
lower-securement portion, which lacks outward protrusions. Such
selective securement allows relative axial reciprocating movement
of struts of the lower-securement portion, while maintaining the
stent as a whole secured in the body lumen. As described above,
such selective securement may thus relieve stresses in the stent
frame resulting from cyclic loads applied to the stent (e.g.,
cyclic cardiac loads) at the one or more tether circumferential
locations, thereby enabling higher fatigue endurance in the stent,
and reducing the risk of stent migration.
[0013] For some applications, the outward protrusions are
rotationally-asymmetrically distributed around the circumference of
the stent, when the stent is unconstrained in the radially-expanded
state. Alternatively or additionally, for some applications, the
outward protrusions are periodically distributed around the
higher-securement circumferential portion, when the stent is
unconstrained in the radially-expanded state. Typically, the
outward protrusions are blunt, when the stent is unconstrained in
the radially-expanded state. Thus, the securement is achieved using
the stent struts themselves, without the need for additional
features such as barbs or hooks which increase the crimp size of
the stent without adding to radial stiffness. Additionally, because
the outward protrusions are blunt, the implant may be less likely
to cause body lumen dissection than if sharp anchoring elements
were provided.
[0014] For some applications, struts of the stent are shaped so as
to define a plurality of columnar struts and a plurality of
circumferential stent meanders, coupled to the columnar struts at
respective axial locations. Typically, each of the circumferential
stent meanders is disposed around the entire circumference of the
stent. A set of one or more of the circumferential stent meanders
are shaped so as to define the outward protrusions at the
respective outward circumferential locations around the
higher-securement portion, when the stent is unconstrained in the
radially-expanded state.
[0015] For some applications, 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 portion, the outward protrusions (the
circumferential stent meander may thus define a polygon if
projected onto a plane perpendicular to a longitudinal axis of the
stent), and (b) around the lower-securement portion, an arc of a
circle if the circumferential stent meander is projected onto the
plane perpendicular to the longitudinal axis of the stent. For some
applications, exactly one, exactly two, exactly three, exactly
four, or five or more of the circumferential stent meanders are
thus shaped.
[0016] In contrast, the other circumferential stent meanders do not
define the outward protrusions, and thus define respective circles
if projected onto the plane perpendicular to the longitudinal axis
of the stent. The stent may be shaped to define other
polygon-circular shape patterns (e.g., every x circumferential
stent meanders may define outward protrusions, such as every second
meander, or every third meander). For some applications, the
lower-securement portion is generally shaped as a circumferential
portion of a circular cylinder.
[0017] For some applications, the stent is shaped so as to define
one or more (e.g., exactly one) tension-distributing elements,
which (a) extend along at least a tether-distribution axial segment
of the stent at the one or more tether circumferential locations,
respectively, (b) define the one or more tether interfaces,
respectively, and (c) are configured to distribute tension applied
by the one or more tethers, respectively, along the
tether-distribution axial segment.
[0018] There is therefore provided, in accordance with an
application of the present invention, apparatus including:
[0019] a radially-expandable stent, which, when unconstrained in a
radially-expanded state, is generally tubular and shaped so as to
define: [0020] one or more tether interfaces at one or more tether
circumferential locations, respectively, each of which tether
interfaces extends circumferentially contiguously around less than
30 degrees of a circumference of the stent, [0021] a
lower-securement portion that extends (a) along at least a
contiguous lower-securement axial segment of the stent and (b)
circumferentially around a contiguous lower-securement
circumferential portion of the stent, which lower-securement axial
segment and lower-securement circumferential portion include the
one or more tether interfaces, [0022] a higher-securement portion
that extends (a) along at least a contiguous higher-securement
axial segment of the stent and (b) circumferentially around between
215 and 330 degrees of the circumference, at all circumferential
locations other than those of the lower-securement circumferential
portion, and [0023] a plurality of outward protrusions at
respective circumferential locations around the higher-securement
portion, and not around the lower-securement portion;
[0024] one or more tissue anchors; and
[0025] one or more tethers having respective first longitudinal
portions that are coupled to the one or more tether interfaces,
respectively, and respective second longitudinal portions,
different from the respective first longitudinal portions, which
are coupled to the one or more tissue anchors, respectively.
[0026] For some applications, the stent is shaped so as to define
one or more tension-distributing elements, which (a) extend along
at least a tension-distribution axial segment of the stent at the
one or more tether circumferential locations, respectively, (b)
define the one or more tether interfaces, respectively, and (c) are
configured to distribute tension applied by the one or more
tethers, respectively, along the tension-distribution axial segment
of the stent. For some applications, the tension-distribution axial
segment axially coincides with the lower-securement axial segment.
For some applications, the one or more tension-distributing
elements and the stent are fabricated from a single unit. For some
applications, each of the one or more tension-distributing elements
has a circumferential arc of between 1 and 15 degrees, when the
stent is unconstrained in the radially-expanded state. For some
applications, an axial length of each of the tension-distributing
elements equals at least 15% of an axial length of the stent. For
some applications, the axial length of the stent is between 20 and
120 mm, and the axial length of each of the tension-distributing
elements is between 10 and 120 mm, when the stent is unconstrained
in the radially-expanded state.
[0027] For some applications, the lower-securement axial segment of
the stent extends along at least 30%, such as at least 100%, of an
axial length of the stent, when the stent is unconstrained in the
radially-expanded state.
[0028] For some applications, an interior of the stent defines a
right circular cylindrical shape having a radius, and 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.
[0029] For some applications, the one or more tether interfaces are
shaped so as to define one or more openings, respectively, through
which the one or more tethers are respectively coupled.
[0030] For some applications, each of the one or more tethers
includes an element selected from the group consisting of: one or
more metal struts, one or more metal wires, one or more flexible
biocompatible textiles, and one or more flexible bands. For some
applications, each of the one or more tethers has a length of
between 20 and 120 mm.
[0031] For some applications, at least one of the one or more
tissue anchors includes a helical tissue anchor.
[0032] For some applications, the stent is a first stent, and at
least one of the one or more tissue anchors includes a second
generally tubular stent.
[0033] For any of the applications described above, the one more
tether interfaces may include exactly one tether interface at
exactly one tether circumferential location, and the one or more
tethers may include exactly one tether having a first longitudinal
portion that is coupled to the tether interface. For some
applications, the tether circumferential location is
circumferentially centered in the lower-securement circumferential
portion. For some applications, the higher-securement portion
extends circumferentially around at least 270 degrees of the
circumference of the stent, when the stent is unconstrained in the
radially-expanded state. For some applications, the exactly one
tether interface is shaped so as to define one or more openings
through which the exactly one tether is coupled.
[0034] For any of the applications described above, the outward
protrusions may be rotationally-asymmetrically distributed around
the circumference of the stent, when the stent is unconstrained in
the radially-expanded state.
[0035] For any of the applications described above, the outward
protrusions may be periodically distributed around the
higher-securement circumferential portion, when the stent is
unconstrained in the radially-expanded state.
[0036] For any of the applications described above, the outward
protrusions may be blunt, when the stent is unconstrained in the
radially-expanded state. Alternatively, for any of the applications
described above, the outward protrusions may be shaped so as to
define respective barbs, when the stent is unconstrained in the
radially-expanded state.
[0037] For any of the applications described above, the
lower-securement portion may have a circumferential arc that 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 portion, when the
stent is unconstrained in the radially-expanded state.
[0038] For any of the applications described above, the stent may
include a plurality of columnar struts and a plurality of
circumferential stent meanders coupled to the columnar struts at
respective axial locations, and one or more of the circumferential
stent meanders may be shaped so as to define the outward
protrusions at the respective circumferential locations around the
higher-securement portion, when the stent is unconstrained in the
radially-expanded state. For some applications, 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 portion, the outward protrusions, and (b)
around the lower-securement portion, an arc of a circle if the
circumferential stent meander is projected onto a plane
perpendicular to a longitudinal axis of the stent. For some
applications, at least one of the circumferential stent meanders is
shaped so as to define the outward protrusions around the
higher-securement portion circumferentially between one or more
circumferentially-adjacent pairs of the columnar struts, when the
stent is unconstrained in the radially-expanded state. For some
applications, at least one of the circumferential stent meanders is
shaped so as to define a plurality of apices, at least some of
which are shaped so as to define the outward protrusions, when the
stent is unconstrained in the radially-expanded state. For some
applications, respective radii of the columnar struts are measured
between respective inner surfaces of the columnar struts and a
central longitudinal axis of the stent, and an average of
respective distances between the central longitudinal axis and
respective most-outward surfaces of the protrusions equals between
105% and 125% of an average of the radii, when the stent is
unconstrained in the radially-expanded state.
[0039] For any of the applications described above, the
higher-securement portion may extend circumferentially around at
least 270 degrees of the circumference of the stent, such as at
least 300 degrees, when the stent is unconstrained in the
radially-expanded state.
[0040] For any of the applications described above, the
higher-securement portion may extend circumferentially around no
more than 300 degrees of the circumference of the stent, when the
stent is unconstrained in the radially-expanded state.
[0041] There is further provided, in accordance with an application
of the present invention, apparatus including:
[0042] a radially-expandable stent, which, when unconstrained in a
radially-expanded state, is generally tubular and shaped so as to
define: [0043] a plurality of tether interfaces at a plurality of
tether circumferential locations, respectively, each of which
tether interfaces extends circumferentially contiguously around
less than 30 degrees of a circumference of the stent, [0044] 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, each of which is between 30
and 90 degrees, [0045] 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 [0046] 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;
[0047] a plurality of tissue anchors; and
[0048] a plurality of tethers having respective first longitudinal
portions that are coupled to the plurality of tether interfaces,
respectively, and respective second longitudinal portions,
different from the respective first longitudinal portions, that are
coupled the plurality of tissue anchors, respectively.
[0049] For some applications, the circumferential arcs of the
lower-securement circumferential portions are equal to one
another.
[0050] For some applications, the higher-securement circumferential
portions have respective circumferential arcs that are equal to one
another.
[0051] For some applications, the circumferential arcs of the
lower-securement circumferential portions are equal to one another,
and the higher-securement circumferential portions have respective
circumferential arcs that are equal to one another.
[0052] For some applications, 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.
For some applications, the tension-distribution axial segments
axially coincide with the lower-securement axial segments,
respectively. For some applications, the tension-distributing
elements and the stent are fabricated from a single unit. For some
applications, 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. For some
applications, an axial length of each of the tension-distributing
elements equals at least 15% of an axial length of the stent. For
some applications, the axial length of the stent is between 20 and
120 mm, and the axial length of each of the tension-distributing
elements is between 10 and 120 mm, when the stent is unconstrained
in the radially-expanded state.
[0053] For some applications, the lower-securement axial segment of
the stent extends along at least 30%, such as at least 100%, of an
axial length of the stent, when the stent is unconstrained in the
radially-expanded state.
[0054] For some applications, an interior of the stent defines a
right circular cylindrical shape having a radius, and 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.
[0055] For some applications, the tether interfaces are shaped so
as to define respective one or more openings through which the
tethers are respectively coupled.
[0056] For some applications, each of the tethers includes an
element selected from the group consisting of: one or more metal
struts, one or more metal wires, one or more flexible biocompatible
textiles, and one or more flexible bands. For some applications,
each of the tethers has a length of between 20 and 120 mm.
[0057] For some applications, at least one of the tissue anchors
includes a helical tissue anchor.
[0058] For some applications, the stent is a first stent, and at
least one of the tissue anchors includes a second generally tubular
stent.
[0059] For any of the applications described above, the stent, when
unconstrained in the radially-expanded state, may be shaped so as
to define a same number of the tether interfaces and the
lower-securement portions. For some applications, the tether
circumferential locations are circumferentially centered in the
lower-securement portions, respectively.
[0060] For any of the applications described above, the outward
protrusions may be rotationally-asymmetrically distributed around
the circumference of the stent, when the stent is unconstrained in
the radially-expanded state.
[0061] For any of the applications described above, the outward
protrusions may be periodically distributed around each of the
higher-securement circumferential portions, when the stent is
unconstrained in the radially-expanded state.
[0062] For any of the applications described above, the outward
protrusions may be blunt, when the stent is unconstrained in the
radially-expanded state. Alternatively, for any of the applications
described above, the outward protrusions may be shaped so as to
define respective barbs, when the stent is unconstrained in the
radially-expanded state.
[0063] For any of the applications described above, each of the
circumferential arcs of the lower-securement circumferential
portions may equal 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.
[0064] For any of the applications described above, the stent may
include a plurality of columnar struts and a plurality of
circumferential stent meanders coupled to the columnar struts at
respective axial locations, and one or more of the circumferential
stent meanders may be 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. For some applications, 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. For some
applications, at least one of the circumferential stent meanders is
shaped so as to define the outward protrusions around the
higher-securement portions circumferentially between one or more
circumferentially-adjacent pairs of the columnar struts, when the
stent is unconstrained in the radially-expanded state. For some
applications, at least one of the circumferential stent meanders is
shaped so as to define a plurality of apices, at least some of
which are shaped so as to define the outward protrusions, when the
stent is unconstrained in the radially-expanded state. For some
applications, respective radii of the columnar struts are measured
between respective inner surfaces of the columnar struts and a
central longitudinal axis of the stent, and an average of
respective distances between the central longitudinal axis and
respective most-outward surfaces of the protrusions equals between
105% and 125% of an average of the radii, when the stent is
unconstrained in the radially-expanded state.
[0065] The present invention will be more fully understood from the
following detailed description of embodiments thereof, taken
together with the drawings, in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0066] FIG. 1 is a schematic illustration of an anchoring system,
in accordance with an application of the present invention;
[0067] FIGS. 2A-D are schematic views of a stent of the anchoring
system of FIG. 1, in accordance with an application of the present
invention;
[0068] FIGS. 3A-B are schematic illustrations of another
configuration of the anchoring system of FIG. 1, in accordance with
an application of the present invention;
[0069] FIGS. 4A-B are schematic illustrations of another
radially-expandable stent, in accordance with an application of the
present invention;
[0070] FIGS. 5A-D are schematic illustrations of an exemplary
deployment of the anchoring system of FIG. 1 for repairing a
tricuspid valve, in accordance with some applications of the
present invention;
[0071] FIGS. 6A-B are schematic illustrations of yet another
radially-expandable stent, in accordance with an application of the
present invention; and
[0072] FIGS. 7A-B are schematic illustrations of a barbed
configuration of the anchoring system of FIG. 1, in accordance with
an application of the present invention.
DETAILED DESCRIPTION OF APPLICATIONS
[0073] FIG. 1 is a schematic illustration of an anchoring system
10, in accordance with an application of the present invention.
Anchoring system 10 comprises a radially-expandable stent 20, and
typically one or more tissue anchors 30 and one or more tethers 34
that connect the stent to the one or more tissue anchors. Stent 20
is configured to be implanted in a body lumen, such as a blood
vessel. For some applications, anchoring system 10 is used for
repairing an atrioventricular valve of a patient using tension,
such as described hereinbelow with reference to FIGS. 5A-D. For
these applications, one or more tissue anchors 30 are implantable
in a vicinity of the atrioventricular valve, and stent 20 is
expanded in a portion of a blood vessel, e.g., a superior vena
cava, an inferior vena cava, a coronary sinus, or a hepatic vein,
e.g., the left hepatic vein, the right hepatic vein, or the middle
hepatic vein.
[0074] Reference is still made to FIG. 1, and is additionally made
to FIGS. 2A-D, which are schematic views of stent 20, in accordance
with an application of the present invention. FIGS. 2A-B are
side-views of stent 20. For sake of illustration, FIG. 2C shows
stent 20 in a flattened state, in which stent 20, when
unconstrained in a radially-expanded state, has been cut
longitudinally and flattened. It is noted that because of the
particular flattened view in FIG. 2C, outward protrusions 70,
described below, are not visible; these protrusions are in fact
present. FIG. 2D is an end-view of stent 20.
[0075] Stent 20 typically comprises a plurality of interconnected
superelastic metallic struts 40. Stent 20 may be manufactured by
expanding a laser-slotted metallic tube, by chemically etching a
flat sheet, by shaping a single wire, by assembling individual wire
elements, or by any other method of construction known in the art.
Stent 20 typically comprises a metal, such as a shape-memory alloy,
e.g., Nitinol.
[0076] Stent 20, when unconstrained in a radially-expanded state
(i.e., no forces are applied to the stent by a delivery tool, wall
of a body vessel, or otherwise), such as shown in FIGS. 1 and 2A-D,
is generally tubular and shaped so as to define: [0077] one or more
tether interfaces 50 at one or more tether circumferential
locations 52, respectively, each of which tether interfaces 50
extends circumferentially contiguously around less than 30 degrees
of a circumference C of stent 20 (labeled in FIG. 2C). In the
configuration shown in FIGS. 1 and 2A-D, stent 20 is shaped so as
to define exactly one tether interface 50 at exactly one tether
circumferential location 52, which extends circumferentially
contiguously around less than 30 degrees of circumference C of
stent 20; [0078] a lower-securement portion 56 that extends (a)
along at least a contiguous lower-securement axial segment 58 of
stent 20 (labeled in FIGS. 2A and 2C) and (b) circumferentially
around a contiguous lower-securement circumferential portion 60 of
stent 20, which lower-securement axial segment 58 and
lower-securement circumferential portion 60 include the one or more
tether interfaces 50 (e.g., exactly one tether interface 50, as
shown in FIGS. 1 and 2A-D). Typically, lower-securement axial
segment 58 extends along at least 30%, e.g., at least 70%, or 100%
(as shown), of an axial length L1 of stent 20; [0079] a
higher-securement portion 64 that extends (a) along at least a
contiguous higher-securement axial segment 65 and (b)
circumferentially around a higher-securement circumferential
portion 66 of stent 20 at all circumferential locations other than
those of lower-securement circumferential portion 60.
Higher-securement circumferential portion 66 typically extends
around at least 215 degrees of circumference C (e.g., at least 270
degrees, or at least 300 degrees), no more than 330 degrees of
circumference C (e.g., no more than 300 degrees), and/or between
215 and 330 degrees of circumference C (e.g., between 270 and 330
degrees, such as between 300 and 330 degrees, or between 270 and
300 degrees); and [0080] a plurality of outward protrusions 70 at
respective outward circumferential locations 72 around
higher-securement portion 64, and not around lower-securement
portion 56.
[0081] Outward protrusions 70 of higher-securement portion 64 cause
higher-securement portion 64 to apply greater securement forces
against the body lumen wall than applied by lower-securement
portion 56, which lacks outward protrusions. Such selective
securement allows relative axial reciprocating movement of struts
40 of lower-securement portion 56, while maintaining the stent as a
whole secured in the body lumen. Such selective securement may thus
relieve stresses in the stent frame resulting from cyclic loads
applied to the stent (e.g., cyclic cardiac loads) at the one or
more tether circumferential locations 52, thereby on the one hand
enabling higher fatigue endurance in the stent, while on the other
hand reducing the risk of stent migration.
[0082] Each of outward protrusions 70 is shaped so as to include a
radially outward directional component. Optionally, each of the
protrusions is shaped so as to additionally include an axial
directional component, i.e., to point toward one end of the stent,
typically pointing against the direction of axial force.
[0083] For some applications, as shown in FIGS. 1 and 2A-D, outward
protrusions 70 are rotationally-asymmetrically distributed around
circumference C of stent 20, when stent 20 is unconstrained in the
radially-expanded state. Alternatively or additionally, for some
applications, also as shown in FIGS. 1 and 2A-D, outward
protrusions 70 are periodically distributed around
higher-securement circumferential portion 66, when stent 20 is
unconstrained in the radially-expanded state.
[0084] Typically, as shown in FIGS. 1 and 2A-D, outward protrusions
70 are blunt, when stent 20 is unconstrained in the
radially-expanded state. Alternatively, outward protrusions 70 are
shaped so as to define respective barbs 530, when stent 20 is
unconstrained in the radially-expanded state, such as described
hereinbelow with reference to FIGS. 7A-B.
[0085] For some applications, an axial length of lower-securement
axial segment 58 is greater than an axial length of
higher-securement axial segment 65, such as at least 10% greater,
e.g., at least 30% or at least 50% greater. Typically,
lower-securement axial segment 58 and higher-securement axial
segment 65 partially axially overlap. For some applications,
higher-securement axial segment 65 is aligned entirely axially
within lower-securement axial segment 58 (although not
circumferentially aligned therewith).
[0086] For some applications (configuration not shown), stent 20
includes a securement portion that does not axially overlap with
either lower-securement axial segment 58 or higher-securement axial
segment 65, and is typically located near the end of stent 20
opposite the end nearest the one or more tether interfaces 50.
[0087] For some applications, struts 40 are shaped so as to define
a plurality of columnar struts 74 and a plurality of
circumferential stent meanders 76 (defining a plurality of apices),
coupled to columnar struts 74 at respective axial locations.
Typically, each of circumferential stent meanders 76 is disposed
around the entire circumference C of stent 20. For example, as
perhaps may best seen in FIG. 2C, stent 20 may have eight
circumferential stent meanders 76 and 14 columnar struts 74. It is
to be understood that other configurations are possible, with any
number of circumferential stent meanders 76. Typically, stent 20
comprises between three circumferential stent meanders 76 (for
short stents, e.g., for a valve frame) and 20 circumferential stent
meanders 76 (for long stents, e.g., for stent-grafts for treating
abdominal aortic aneurisms ("AAAs")), and any number of columnar
struts 74, typically between six and 20.
[0088] A set 80 of one or more of circumferential stent meanders 76
are shaped so as to define outward protrusions 70 at respective
outward circumferential locations 72 around higher-securement
portion 64, when stent 20 is unconstrained in the radially-expanded
state. For some applications, each of circumferential stent
meanders 76 of set 80 defines a number of outward protrusions 70
equal to between 20% and 100% of the total number of apices of the
stent meander around the entire circumference C of the stent, such
as between 50% and 90%, e.g., 86% (12/14). For some applications,
each of circumferential stent meanders 76 of set 80 defines between
3 and 20 of outward protrusions 70, such as between 6 and 14 of
outward protrusions 70, e.g., 12 of outward protrusions.
[0089] For some applications, when stent 20 is unconstrained in the
radially-expanded state, at least one of circumferential stent
meanders 76 is shaped so as to define: [0090] around
higher-securement portion 64, outward protrusions 70 (the
circumferential stent meander may thus define a polygon if
projected onto a plane perpendicular to a longitudinal axis 82 of
stent 20); and [0091] around lower-securement portion 56, an arc of
a circle if the circumferential stent meander is projected onto the
plane perpendicular to longitudinal axis 82 of stent 20. For some
applications, exactly one, exactly two, exactly three (as shown),
exactly four, or five or more of circumferential stent meanders 76
are thus shaped. For example, first, third, and fifth distal
circumferential stent meanders 76A, 76C, and 76E include: [0092]
respective portions around higher-securement portion 64, which
define outward protrusions 70 (and thus define respective polygons
if projected onto the plane perpendicular to longitudinal axis 82
of stent 20), and [0093] respective portions around
lower-securement portion 56, which do not define outward
protrusions 70 (and thus define respective arcs of a circle if
projected onto the plane perpendicular to longitudinal axis 82 of
stent 20). In contrast, second, fourth, sixth, seventh, and eighth
circumferential stent meanders 76B, 76D, 76F, 76G, and 76H do not
define outward protrusions 70, and thus define respective circles
if projected onto the plane perpendicular to longitudinal axis 82
of stent 20. Stent 20 may be shaped to define other
polygon-circular shape patterns (e.g., every x circumferential
stent meanders 76 may define outward protrusions, such as every
second meander, or every third meander). For some applications,
lower-securement portion 56 is generally shaped as a
circumferential portion of a circular cylinder. Such providing of
lower-securement axial spaces between circumferential stent
meanders may facilitate better fatigue resistance. In addition, the
securement is provided by a plurality of circumferential stent
meanders 76 at a respective plurality of axial locations, rather
than only by a single row at one end of the stent, or single rows
at each end of the stent, as in some conventional stents.
[0094] For some applications, when stent 20 is unconstrained in the
radially-expanded state, at least one of circumferential stent
meanders 76 is shaped so as to define outward protrusions 70 around
higher-securement portion 64 circumferentially between one or more
circumferentially-adjacent pairs 84 of columnar struts 74, such as
between every circumferentially-adjacent pair of columnar struts 74
around higher-securement portion 64, as shown). For some
applications, exactly one, exactly two, exactly three (as shown and
described above), exactly four, or five or more of circumferential
stent meanders 76 are thus shaped.
[0095] For some applications, outward protrusions 70 are cascaded
around higher-securement portion 64.
[0096] For some applications, at least one of circumferential stent
meanders 76 is shaped so as to define a plurality of apices 86, at
least some of which are shaped so as to define outward protrusions
70, when stent 20 is unconstrained in the radially-expanded
state.
[0097] For some applications, when stent 20 is unconstrained in the
radially-expanded state, respective radii R of columnar struts 74
are measured between respective inner surfaces of columnar struts
74 and central longitudinal axis 82 of the stent. An average of
respective distances D1 between respective most-outward surfaces 88
of outward protrusions 70 equals between 105% and 125% of an
average of radii R. For applications in which stent 20 is shaped
generally as a circular cylinder, radii R equal one another, and
distances D1 typically equal one another. Alternatively or
additionally, for some applications, when stent 20 is unconstrained
in the radially-expanded state, outward protrusions 70 have a
length P of at least 1 mm, no more than 5 mm, and/or between 1 and
5 mm, measured from an outer surface 90 of stent 20 other than at
the protrusions. Further alternatively or additionally, for some
applications, wherein an interior of stent 20 defines a right
circular cylindrical shape having radius R, and outward protrusions
70 extend radially outward from the cylindrical shape by a distance
equal to between 5% and 25% of radius R, when stent 20 is
unconstrained in the radially-expanded state.
[0098] The dimensions of stent 20 may vary in order to fit the body
lumen in which it is placed, according to the medical application.
Typically, when unconstrained in the radially-expanded state, stent
20 has (a) an inner diameter D2 that equals about 10-30% larger
than the inner diameter of the body lumen, and/or (b) axial length
L1 that equals between 100% and 600% of inner diameter D2. For
example, for applications in which stent 20 is configured to be
implanted a vena cava for tethering anchor 30 at the tricuspid
valve, such as described hereinbelow with reference to FIGS. 5A-D,
(a) inner diameter D2 may be at least 25 mm, no more than 60 mm,
and/or between 25 and 60 mm, (b) stent length L1 may be at least 25
mm, no more than 100 mm, and/or between 25 and 100 mm, and (c)
protrusion length P may be 3 mm. For applications in which stent 20
is configured to be implanted in the abdominal aorta, (a) inner
diameter D2 may be at least 30 mm, no more than 50 mm, and/or
between 30 and 50 mm, (b) stent length L1 may be at least 50 mm, no
more than 300 mm, and/or between 50 and 300 mm, and (c) protrusion
length P may be 5 mm. For some applications, stent length L1 is at
least 20 mm, no more than 120 mm, and/or between 20 and 120 mm,
when stent 20 is unconstrained in the radially-expanded state.
[0099] Typically, inner diameter D2 is constant along the stent,
i.e., the stent is not flared at either end.
[0100] For some applications, stent 20 is shaped so as to define
one or more (e.g., exactly one) tension-distributing elements 94,
which (a) extend along at least a tether-distribution axial segment
95 of stent 20 at the one or more tether circumferential locations
52, respectively, (b) define the one or more tether interfaces 50,
respectively, and (c) are configured to distribute tension applied
by the one or more tethers 34, respectively, along
tether-distribution axial segment 95. For some applications, as
shown, tether-distribution axial segment 95 axially coincides with
lower-securement axial segment 58. Optionally, the one or more
tension-distributing elements 94 and stent 20 are fabricated from a
single unit.
[0101] For some applications, each of the one or more
tension-distributing elements 94 has a circumferential arc A1
(labeled in FIG. 2C) of at least 1 degree, no more than 15 degrees,
and/or between 1 and 15 degrees when stent 20 is unconstrained in
the radially-expanded state. For some applications, an axial length
L2 of each of tension-distributing elements 94 equals at least 15%
of axial length L1 of stent 20, such as at least 75% of axial
length L1 of stent 20. For some applications, such as when stent
length L1 is at least 20 mm, no more than 120 mm, and/or between 20
and 120 mm, axial length L2 of each of tension-distributing
elements 94 is at least 10 mm, no more than 120, and/or between 10
and 120 mm, when stent 20 is unconstrained in the radially-expanded
state.
[0102] For some applications, lower-securement portion 56 has a
circumferential arc A2 that equals at least 150% (e.g., at least
200%) of an average of circumferential distances D3 between
circumferential midpoints 96 of circumferentially-adjacent ones 98
of outward protrusions 70 around higher-securement portion 64, when
stent 20 is unconstrained in the radially-expanded state.
[0103] Reference is again made to FIG. 1. The one or more tethers
34 have respective first longitudinal portions 100 that are coupled
to the one or more tether interfaces 50, respectively, and
respective second longitudinal portions 102, different from
respective first longitudinal portions 100, which are coupled to
the one or more tissue anchors 30, respectively. For some
applications, the one or more tether interfaces 50 are shaped so as
to define one or more openings 104, respectively, through which the
one or more tethers 34 are respectively coupled.
[0104] For some applications, each of the one or more tethers 34
comprises an element selected from the group consisting of: one or
more metal struts, one or more metal wires, one or more flexible
biocompatible textiles, and one or more flexible bands. For some
applications, each of the one or more tethers 34 has a length of at
least 20 mm, no more than 120 mm, and/or between 20 and 120 mm.
[0105] For some applications, at least one of the one or more
tissue anchors 30 comprises a helical tissue anchor. For some
applications, the helical tissue anchor comprises a generally
helical shaftless tissue-coupling element 106 and, typically, a
proximal head 108. For some applications, such as described in U.S.
Provisional Application 61/750,427, filed Jan. 9, 2013, which is
assigned to the assignee of the present application and is
incorporated herein by reference, helical tissue-coupling element
106 has (a) a first axial thickness along a first axial portion of
a shaftless helical portion of the helical tissue-coupling element,
and (b) a second axial thickness along a second axial portion of
the shaftless helical portion more distal than the first axial
portion. The second axial thickness is greater than the first axial
thickness. The first and second axial thicknesses are measured
along a longitudinal axis of the helical tissue-coupling element.
Alternatively or additionally, the helical tissue-coupling element
has (a) a first axial yield strength along the first axial portion,
and (b) a second axial yield strength along the second axial
portion (more distal than the first axial portion). The second
axial yield strength is greater than the first axial yield
strength. Further alternatively or additionally, the helical
tissue-coupling element has (a) a first axial stiffness along the
first axial portion, and (b) a second axial stiffness along the
second axial portion (more distal than the first axial portion).
The second axial stiffness is greater than the first axial
stiffness.
[0106] For some applications, such as described in the
above-mentioned '427 application, the helical tissue-coupling
element 106 is shaped so as to define (a) a first surface along a
first axial surface characteristic portion of the shaftless helical
portion of the helical tissue-coupling element, which first surface
has a first surface characteristic, and (b) a second surface along
a second axial surface characteristic portion of the shaftless
helical portion different from the first axial surface
characteristic portion. The second surface has a second surface
characteristic that is configured to inhibit rotation of the
helical tissue-coupling element to a greater extent than does the
first surface characteristic. The first surface characteristic may,
for example, be a high level of smoothness.
[0107] For some applications, stent 20 is a first stent, and at
least one of the one or more tissue anchors 30 comprises a second
generally tubular stent. A similar two-stent configuration (albeit
without the stent configurations described herein) is shown, for
example, in FIG. 4C of PCT Publication WO 2013/011502, which is
incorporated herein by reference. For some applications, the second
stent is expanded in a portion of a second blood vessel of the
patient, e.g., the superior vena cava, the inferior vena cava, the
coronary sinus, or a hepatic vein, e.g., the left hepatic vein, the
right hepatic vein, or the middle hepatic vein.
[0108] For some applications, as shown in FIGS. 1 and 2A-D, the one
more tether interfaces 50 comprise exactly one tether interface 50
at exactly one tether circumferential location 52, and the one or
more tethers 34 comprise exactly one tether 34 having a first
longitudinal portion that is coupled to the tether interface. In
some of these applications, higher-securement portion 64 extends
circumferentially around at least 270 degrees of circumference C of
stent 20, when stent 20 is unconstrained in the radially-expanded
state.
[0109] For some applications, tether circumferential location 52 is
circumferentially centered in lower-securement circumferential
portion 60, as shown in FIGS. 2A-D. Alternatively, tether
circumferential location 52 is not circumferentially centered in
lower-securement circumferential portion 60 (configuration not
shown). For some applications, the exactly one tether interface is
shaped so as to define the one or more openings 104 through which
the exactly one tether is coupled.
[0110] Reference is now made to FIGS. 3A-B, which are schematic
illustrations of another configuration of anchoring system 10, in
accordance with an application of the present invention. In this
configuration, anchoring system 10 comprises a radially-expandable
stent 120, which is one configuration of stent 20 described
hereinabove with reference to FIGS. 1 and 2A-D. As mentioned above,
anchoring system 10 typically comprises one or more tissue anchors
30 and one or more tethers 34 that connect the stent to the one or
more tissue anchors. Also as mentioned above, stent 20, when
unconstrained in the radially-expanded state (i.e., no forces are
applied to the stent by a delivery tool, wall of a body vessel, or
otherwise), is shaped so as to define one or more tether interfaces
50 at one or more tether circumferential locations 52,
respectively.
[0111] In the configuration shown in FIGS. 3A-B, anchoring system
comprises two tissue anchors 30 and two tethers 34 that connect
stent 120 to the two tissue anchors, respectively. Stent 120 is
shaped so as to define two tether interfaces 50 at two tether
circumferential locations 52, respectively, each of which extends
circumferentially contiguously around less than 30 degrees of
circumference C of stent 20. Two tethers 34 have respective first
longitudinal portions 100 that are coupled to two tether interfaces
50, respectively, and two respective second longitudinal portions
102, different from respective first longitudinal portions 100,
which are coupled to two tissue anchors 30, respectively.
[0112] This configuration may be useful for applying tension to two
sites to which the two anchors are coupled, such as two sites of
the tricuspid valve. For example, this configuration may be used in
combination with the anchor placement described with reference to,
and shown in, FIG. 2B and/or FIG. 3B of above-mentioned PCT
Publication WO 2013/011502, mutatis mutandis.
[0113] Reference is now made to FIGS. 4A-B, which are schematic
illustrations of another radially-expandable stent 220, in
accordance with an application of the present invention. FIGS. 4A
and 4B are side- and end-views of stent 220, respectively. In this
configuration, anchoring system 10 comprises radially-expandable
stent 220, a plurality (e.g., two) of tissue anchors 30 and a
plurality (e.g., two) of tethers 34 that connect the stent to the
one or more tissue anchors. Other than as described below, stent
220 may have any of the features of stent 20, described hereinabove
with reference to FIGS. 1 and 2A-D.
[0114] Stent 220 typically comprises a plurality of interconnected
superelastic metallic struts 40, and may be manufactured as
described hereinabove regarding stent 20. Stent 220, when
unconstrained in a radially-expanded state (i.e., no forces are
applied to the stent by a delivery tool, wall of a body vessel, or
otherwise), such as shown in FIGS. 4A-D, is generally tubular and
shaped so as to define: [0115] a plurality of tether interfaces 50
at a plurality of tether circumferential locations 52,
respectively, each of which tether interfaces 50 extends
circumferentially contiguously around less than 30 degrees of a
circumference of stent 220. In the configuration shown in FIGS.
4A-B, stent 220 is shaped so as to define two tether interfaces 50
at two tether interface locations 52; [0116] a plurality of
lower-securement portions 56 that extend (a) along at least
respective contiguous lower-securement axial segments 58 of stent
220 and (b) circumferentially around respective contiguous
lower-securement circumferential portions 60 of stent 220. Each of
lower-securement axial segments 58 includes one or more of tether
interfaces 50 (e.g., exactly one of tether interfaces 50, as shown
in FIGS. 4A-B). Each of lower-securement circumferential portions
60 includes one or more of tether interfaces 50 (e.g., exactly one
of tether interfaces 50, as shown in FIGS. 4A-B). Lower-securement
portions 56 have respective circumferential arcs, each of which
typically is between 30 and 90 degrees; [0117] a plurality of
higher-securement portions 64 that extend (a) along at least
respective contiguous higher-securement axial segments 65 and (b)
circumferentially around respective higher-securement
circumferential portions 66 of stent 220, collectively at all
circumferential locations other than those lower-securement
circumferential portions 60. Lower- and higher-securement portions
56 and 64 alternate around stent 220 (such that there are an equal
number of lower- and higher-securement portions 56 and 64); and
[0118] a plurality of outward protrusions 70 at respective outward
circumferential locations 72 around higher-securement portions 64,
and not around lower-securement portions 56, such that each of
higher-securement portions 64 includes one or more of outward
protrusions 70.
[0119] Outward protrusions 70 of higher-securement portion 64 cause
higher-securement portion 64 to apply greater securement forces
against the body lumen wall than applied by lower-securement
portion 56, which lacks outward protrusions. Such selective
securement allows relative axial reciprocating movement of struts
40 of lower-securement portion 56, while maintaining the stent as a
whole secured in the body lumen. Such selective securement may thus
relieve stresses in the stent frame resulting from cyclic loads
applied to the stent (e.g., cyclic cardiac loads) at tether
circumferential locations 52, thereby enabling higher fatigue
endurance in the stent.
[0120] For some applications, the circumferential arcs of
lower-securement circumferential portions 60 are equal to one
another. Alternatively or additionally, for some applications,
higher-securement circumferential portions 66 have respective
circumferential arcs that are equal to one another.
[0121] For some applications, stent 220, when unconstrained in the
radially-expanded state, is shaped so as to define a same number of
tether interfaces 50 and lower-securement portions 56. For some
applications, tether circumferential locations 52 are
circumferentially centered in lower-securement circumferential
portions 60, respectively, as shown in FIGS. 4A-B. Alternatively,
tether circumferential locations 52 are not circumferentially
centered in lower-securement circumferential portions 60,
respectively (configuration not shown).
[0122] For some applications, struts 40 are shaped so as to define
the plurality of columnar struts 74 and the plurality of
circumferential stent meanders 76 coupled to columnar struts 74 at
respective axial locations. Typically, each of circumferential
stent meanders 76 is disposed around the entire circumference of
stent 220. For some applications, when stent 220 is unconstrained
in the radially-expanded state, at least one of circumferential
stent meanders 76 is shaped so as to define (a) around
higher-securement portions 64, outward protrusions 70, and (b)
around lower-securement portions 56, respective arcs of a circle if
the circumferential stent meander is projected onto a plane
perpendicular to longitudinal axis 82 of stent 220.
[0123] As mentioned above, stent 220 may have any of the features
of stent 20, described hereinabove with reference to FIGS. 1 and
2A-D. Such features include, but are not limited to, (a) a
plurality of tension-distributing elements 94, which are configured
to distribute tension applied by tethers 34, respectively, along
the axial portion of stent 220, (b) the rotationally asymmetric
distribution of outward protrusions 70 around the circumference of
stent 220, when stent 220 is unconstrained in the radially-expanded
state, and (c) the periodic distribution of outward protrusions 70
around each of higher-securement circumferential portions 66, when
stent 220 is unconstrained in the radially-expanded state.
[0124] The configuration described with reference to FIGS. 4A-B may
be useful for applying tension to two sites to which the two
anchors are coupled, such as two sites of the tricuspid valve. For
example, this configuration may be used in combination with the
anchor placement described with reference to, and shown in, FIG. 2B
and/or FIG. 3B of above-mentioned PCT Publication WO 2013/011502,
mutatis mutandis.
[0125] Reference is now made to FIGS. 5A-D, which are schematic
illustrations of an exemplary deployment of anchoring system 10 for
repairing a tricuspid valve 304 of a heart 302 of a patient, in
accordance with some applications of the present invention.
Although FIGS. 5A-D show the deployment of stent 20, described
hereinabove with reference to FIGS. 1 and 2A-D, the same
techniques, mutatis mutandis, may be used for deploying stent 120,
described hereinabove with reference to FIGS. 3A-B, stent 220,
described hereinabove with reference to FIGS. 4A-B, and stent 420,
described hereinbelow with reference to FIGS. 6A-B.
[0126] System 10 is used for adjusting a distance between first and
second implantation sites by pulling to apply tension to or
relaxing tether 34 and/or by applying tension to at least one of
tissue anchor 30 and stent 20. Responsively, a distance between the
leaflets of tricuspid valve 304 is adjusted to reduce and eliminate
regurgitation through valve 304, and thereby, valve 304 is
repaired. For some applications, tether 34 is pulled or relaxed by
manipulating stent 20, as is described hereinbelow.
[0127] For some applications, stent 20 is advanced toward and
expanded in a portion of an inferior vena cava 308 (such as shown
in FIGS. 5A-D) or a superior vena cava 310 (such as shown in FIGS.
1E-G of the above-mentioned '601 publication), i.e., a blood vessel
that is in direct contact with a right atrium 306 of heart 302.
[0128] FIG. 5A shows the advancement of a catheter 322 toward
atrium 306 until a distal end 323 of the catheter is disposed
within atrium 306. The procedure is typically performed with the
aid of imaging, such as fluoroscopy, transesophageal echo, and/or
echocardiography. For some applications, the procedure begins by
advancing a semi-rigid guidewire into right atrium 306 of the
patient. The guidewire provides a guide for the subsequent
advancement of catheter 322 therealong and into the right atrium.
Catheter 322 typically comprises a 14-20 F sheath, although the
size may be selected as appropriate for a given patient. Catheter
322 is advanced through vasculature into right atrium 306 using a
suitable point of origin typically determined for a given patient,
such as described in PCT Publication WO 2011/089601, which is
assigned to the assignee of the present application and is
incorporated herein by reference.
[0129] Once distal end 323 of catheter 322 is disposed within
atrium 306, an anchor-deployment tube 324 is extended from within
catheter 322 beyond distal end 323 thereof and toward a first
implantation site 330. Anchor-deployment tube 324 holds tissue
anchor 30 and a distal portion of tether 34. For some applications,
tube 324 is steerable, as is known in the catheter art, while for
other applications, a separate steerable element may be coupled to
anchor-deployment tube 324. Under the aid of imaging guidance,
anchor-deployment tube 324 is advanced toward first implantation
site 330 until a distal end thereof contacts cardiac tissue of
heart 302 at first implantation site 330. Anchor-deployment tube
324 facilitates atraumatic advancement of tissue anchor 30 toward
first implantation site 330. For such applications in which
anchor-deployment tube 324 is used, stent 20 is compressed within a
portion of tube 324.
[0130] As shown, first implantation site 330 comprises a portion of
an annulus of tricuspid valve 304. Implantation site 330 typically
comprises a portion of the annulus of valve 304 that is between (1)
the middle of the junction between the annulus and anterior leaflet
314, and (2) the middle of the junction between the annulus and
posterior leaflet 316, e.g., between the middle of the junction
between the annulus and anterior leaflet 314 and the commissure
between the anterior and posterior leaflets. That is, tissue anchor
30 is coupled to, e.g., screwed into, the fibrous tissue of the
tricuspid annulus close to the commissure in between anterior
leaflet 314 and posterior leaflet 316. Implantation site 330 is
typically close to the mural side of valve 304. For such
applications, the drawing together of first and second implantation
sites 330 and 352 cinches valve 304 and may create a
bicuspidization of tricuspid valve 304, and thereby achieve
stronger coaptation between anterior leaflet 314 and septal leaflet
312.
[0131] As shown in FIG. 5B, an anchor-manipulating tool (not shown
for clarity of illustration), which is slidably disposed within
anchor-deployment tube 324, is slid distally within tube 324 so as
to push distally tissue anchor 30 and expose tissue anchor 30 from
within tube 324. For some applications of the present invention,
the anchor-manipulating tool is reversibly coupled to tissue anchor
30 and facilitates implantation of tissue anchor 30 in the cardiac
tissue.
[0132] The physician rotates the anchor-manipulating tool from a
site outside the body of the patient in order to rotate tissue
anchor 30 and thereby screw at least a portion of tissue anchor 30
in the cardiac tissue. Alternatively, system 320 is provided
independently of the anchor-manipulating tool, and
anchor-deployment tube 324 facilitates implantation of tissue
anchor 30 in the cardiac tissue. The physician rotates
anchor-deployment tube 324 from a site outside the body of the
patient in order to rotate tissue anchor 30 and thereby screw at
least a portion of tissue anchor 30 in the cardiac tissue.
[0133] As shown in FIG. 5C, following the implantation of tissue
anchor 30 at first implantation site 330, anchor-deployment tube
324 is retracted within catheter 322 in order to expose tether 34.
Subsequently, tether 34 is tensioned in order to repair tricuspid
valve 304, as described hereinbelow.
[0134] For some applications, prior to pulling the portion of
tether 34 that is disposed between tissue anchor 30 and distal end
323 of catheter 322, a mechanism that facilitates the application
of a pulling force to tether 34 is fixed in place, as described in
the above-mentioned '601 publication.
[0135] For some applications, catheter 322 is reversibly coupled to
a proximal portion of tether 34 by being directly coupled to the
proximal portion of tether 34 and/or catheter 322 is reversibly
coupled to stent 20. For example, catheter 322 may be reversibly
coupled to stent 20 by the stent's application of a radial force
against the inner wall of catheter 322 because of the tendency of
stent 20 to expand radially. Following implantation of tissue
anchor 30, catheter 322 (or an element disposed therein) is then
pulled proximally to apply tension to tether 34, which, in such an
application, functions as a tensioning element. For some
applications, catheter 322 pulls on stent 20 in order to pull
tether 34. For other applications, catheter 322 pulls directly on
tether 34. For yet other applications, a pulling mechanism pulls on
tether 34, as is described with reference to FIGS. 5A-D in the
above-referenced '601 publication.
[0136] Pulling tether 34 pulls taut the portion of tether 34 that
is disposed between tissue anchor 30 and distal end 323 of catheter
322. Responsively to the pulling of tether 34, at least the
anterior and septal leaflets of tricuspid valve 304 are drawn
together because the geometry of the annulus and/or of the wall of
atrium 306 is altered in accordance with the pulling of tether 34
and depending on the positioning of tissue anchor 30.
[0137] For some applications, during the pulling of tether 34 by
catheter 322, a level of regurgitation of tricuspid valve 304 is
monitored. Tether 34 is pulled until the regurgitation is reduced
or ceases. Once the physician determines that the regurgitation of
valve 304 is reduced or ceases, and valve 304 has been repaired,
the physician decouples catheter 322 from stent 20 disposed therein
and/or from tether 34, and then retracts catheter 322 in order to
expose stent 20. During the advancement of catheter 322 toward
atrium 306, stent 20 is disposed within a distal portion of
catheter 322 in a compressed state. Following initial retracting of
catheter 322, stent 20 is exposed and is allowed to expand and
contact a wall of inferior vena cava 308.
[0138] FIG. 5D shows stent 20 fully exposed and fully expanded, and
thus implanted in inferior vena cava 308. Stent 20 maintains the
tension of tether 34 on tissue anchor 30 and thereby on the portion
of cardiac tissue to which tissue anchor 30 is coupled.
[0139] The techniques described with reference to FIGS. 5A-B may be
performed in combination with techniques described in the
above-mentioned '601 publication, mutatis mutandis.
[0140] As described above, for some applications the techniques
described herein are used to repair the tricuspid valve. The
techniques described herein may also be used to repair the mitral
valve of the patient, mutatis mutandis.
[0141] Reference is now made to FIGS. 6A-B, which are schematic
illustrations of another radially-expandable stent 420, in
accordance with an application of the present invention. FIGS. 6A
and 6B are side- and end-views of stent 420, respectively. In this
configuration, anchoring system 10 comprises radially-expandable
stent 420, one or more tissue anchors 30, and one or more tethers
34 that connect the stent to the one or more tissue anchors. Other
than as described below, stent 420 may have any of the features of
stent 20, described hereinabove with reference to FIGS. 1 and 2A-D,
stent 120, described hereinabove with reference to FIGS. 3A-D,
and/or stent 220, described hereinabove with reference to FIGS.
4A-D.
[0142] Unlike stents 20, 120, and 220, stent 420 is not shaped so
as to define lower-securement portion 56. Thus, the portion of
stent 420 that includes one or more tether interfaces 50 (e.g.,
exactly one tether interface 50) at one or more tether
circumferential locations 52 (e.g., at exactly one tether
circumferential location 52) provides the same level of securement
to the body lumen as do the other portions of the stent.
[0143] When stent 420 is unconstrained in the radially-expanded
state (i.e., no forces are applied to the stent by a delivery tool,
wall of a body vessel, or otherwise), only a portion of
circumferential stent meanders 76 (e.g., exactly one, exactly two,
exactly three (as shown), exactly four, or five or more of
circumferential stent meanders 76) are shaped so as to define one
or more outward protrusions. For example, first, third, and fifth
distal circumferential stent meanders 76A, 76C, and 76E may define
outward protrusions 70, and thus define respective polygons if
projected onto the plane perpendicular to longitudinal axis 82 of
stent 420. In contrast, the other circumferential stent meanders
may not define any outward protrusions 70, and thus define
respective circles if projected onto the plane perpendicular to
longitudinal axis 82 of stent 420. Stent 420 may be shaped to
define other polygon-circular shape patterns (e.g., every x
circumferential stent meanders 76 may define outward protrusions,
such as every second meander, or every third meander). Such
providing of lower-securement axial spaces between circumferential
stent meanders may facilitate better tissue fixation by scattering
the protrusions.
[0144] For some applications, when stent 420 is unconstrained in
the radially-expanded state, at least one of circumferential stent
meanders 76 is shaped so as to define outward protrusions 70
circumferentially between one or more circumferentially-adjacent
pairs 84 of columnar struts 74, such as between every
circumferentially-adjacent pair of columnar struts 74. For some
applications, exactly one, exactly two, exactly three (as shown and
described above), exactly four, or five or more of circumferential
stent meanders 76 are thus shaped.
[0145] For some applications, outward protrusions 70 are cascaded
around stent 420.
[0146] Reference is now made to FIGS. 7A-B, which are schematic
illustrations of a barbed configuration of anchoring system 10, in
accordance with an application of the present invention. In this
configuration, anchoring system 10 comprises a radially-expandable
stent 520, which is one configuration of stent 20 described
hereinabove with reference to FIGS. 1 and 2A-D. As mentioned above,
anchoring system 10 typically comprises one or more tissue anchors
30 and one or more tethers 34 that connect the stent to the one or
more tissue anchors. Also as mentioned above, stent 20, when
unconstrained in the radially-expanded state, is shaped so as to
define one or more tether interfaces 50 at one or more tether
circumferential locations 52, respectively.
[0147] In this configuration, unlike the configurations shown in
the other figures, outward protrusions 70 are shaped so as to
define respective barbs 530, when stent 520 is unconstrained in the
radially-expanded state (i.e., no forces are applied to the stent
by a delivery tool, wall of a body vessel, or otherwise). The barbs
may aid in securing higher-securement portion 64 of stent 520 to
the vessel wall. The barbs may protrude from one or more of
columnar struts 74 of higher-securement portion 64, as shown, or
from one or more of circumferential stent meanders 76 of
higher-securement portion 64 (configuration not shown).
Medical Applications
[0148] The anchoring system and stents described herein may be used
for a number of different medical applications, including but not
limited to the following applications. For some of these
applications, tissue anchors 30 and tethers 34 are not provided.
[0149] The anchor system and stents described herein may be used in
tricuspid valve repair, such as described hereinabove with
reference to FIGS. 5A-D. One of the stents may be used as an anchor
point in the vena cava, to tether the tissue anchor which is
coupled to the native valve (typically at the anterior-posterior
commissure), thus lowering the anterior-posterior commissure and
diminishing regurgitation. [0150] The stents described herein may
be used in aortic transcatheter valve implantation (TAVI), as a
frame for the valve. The unique designs of the stent allow
anchoring the prosthetic valve more securely to the native annulus,
thereby preventing the prosthetic valve from migration at early and
midterm follow-up. The stents described herein may also be used for
mitral, pulmonary, and tricuspid replacement, using a transfemoral,
transaxillary, transaortic, or transapical approach. [0151] The
stents described herein may be coupled to a filter, and may be
used, for example, as a vena cava filter in patients suffering from
a disorder of coagulation, in order to prevent pulmonary
thromboembolism. [0152] The stents described herein may be used as
a transjugular intrahepatic portocaval shunt (TIPS) in patients
suffering from cirrhosis and portal hypertension. [0153] The stents
described herein may be used for endoprosthesis placement in aortic
abdominal and bisiliac vascular aneurism. [0154] The stents
described herein may be used for thoracic endovascular aortic
repair (TEVAR) or for traditional open surgery elephant trunk or
frozen elephant trunk technique in descending aortic thoracic and
in Stanford Type A aortic dissection. [0155] The stents described
herein may be used for treating prostatic hypertrophy in patients
suffering from prostate enlargement. [0156] The stents described
herein may be used be used to stent oncologic patients suffering
from partial obstruction of the trachea.
[0157] As used in the present application, including in the claims,
"tubular" means having the form of an elongated hollow object that
defines a conduit therethrough. A "tubular" structure may have
varied cross-sections therealong, and the cross-sections are not
necessarily circular. For example, one or more of the
cross-sections may be generally circular, or generally elliptical
but not circular, or circular.
[0158] The scope of the present invention includes embodiments
described in the following applications, which are assigned to the
assignee of the present application and are incorporated herein by
reference. In an embodiment, techniques and apparatus described in
one or more of the following applications are combined with
techniques and apparatus described herein: [0159] U.S. application
Ser. No. 12/692,061, filed Jan. 22, 2010, which published as US
Patent Application Publication 2011/0184510; [0160] International
Application PCT/IL2011/000064, filed Jan. 20, 2011, which published
as PCT Publication WO 2011/089601, and U.S. application Ser. No.
13/574,088 in the national stage thereof, which published as US
Patent Application Publication 2013/0046380; [0161] U.S.
application Ser. No. 13/188,175, filed Jul. 21, 2011, which
published as US Patent Application Publication 2012/0035712; [0162]
U.S. application Ser. No. 13/485,145, filed May 31, 2012, which
published as US Patent Application Publication 2013/0325115; [0163]
U.S. application Ser. No. 13/553,081, filed Jul. 19, 2012, which
published as US Patent Application Publication 2013/0018459; [0164]
International Application PCT/IL2012/000282, filed Jul. 19, 2012,
which published as PCT Publication WO 2013/011502; [0165] U.S.
Provisional Application 61/750,427, filed Jan. 9, 2013, entitled,
"Soft tissue anchors and implantation techniques"; and [0166]
International Application PCT/IL2014/050027, filed Jan. 9, 2014,
which published as PCT Publication WO 2014/108903.
[0167] In particular, the stents described herein may be used as
one or more of the stents described in the above-listed
applications, in combination with the other techniques described
therein.
[0168] It will be appreciated by persons skilled in the art that
the present invention is not limited to what has been particularly
shown and described hereinabove. Rather, the scope of the present
invention includes both combinations and subcombinations of the
various features described hereinabove, as well as variations and
modifications thereof that are not in the prior art, which would
occur to persons skilled in the art upon reading the foregoing
description.
* * * * *