U.S. patent application number 10/595926 was filed with the patent office on 2007-02-01 for vascular implant.
This patent application is currently assigned to Neovasc Medical LTD. Invention is credited to Shmuel Ben-Muvhar.
Application Number | 20070027525 10/595926 |
Document ID | / |
Family ID | 34044288 |
Filed Date | 2007-02-01 |
United States Patent
Application |
20070027525 |
Kind Code |
A1 |
Ben-Muvhar; Shmuel |
February 1, 2007 |
Vascular implant
Abstract
A medical implant (20) includes first and second ring members
(22,24), each including a resilient framework (26) having a
generally cylindrical form. A tubular sleeve (28) is fixed to the
first and second ring members so as to hold the ring members in
mutual longitudinal alignment, thereby defining a lumen (32)
passing through the ring members. A constricting element (30) is
fit around the sleeve at a location intermediate the first and
second ring members so as to reduce a diameter of the lumen at the
location.
Inventors: |
Ben-Muvhar; Shmuel; (Emek
Beit Shean, IL) |
Correspondence
Address: |
DARBY & DARBY P.C.
P. O. BOX 5257
NEW YORK
NY
10150-5257
US
|
Assignee: |
Neovasc Medical LTD
Or Yehuda
IL
60376
|
Family ID: |
34044288 |
Appl. No.: |
10/595926 |
Filed: |
November 18, 2004 |
PCT Filed: |
November 18, 2004 |
PCT NO: |
PCT/IL04/01063 |
371 Date: |
July 12, 2006 |
Current U.S.
Class: |
623/1.12 ;
606/158; 623/1.13 |
Current CPC
Class: |
A61B 17/1285 20130101;
A61F 2250/0039 20130101; A61F 2/962 20130101; A61F 2002/068
20130101; A61F 2/966 20130101; A61B 17/1227 20130101; A61F 2002/826
20130101; A61F 2250/0071 20130101; A61F 2/95 20130101; A61F
2230/0078 20130101; A61F 2/82 20130101; A61F 2230/0054 20130101;
A61F 2002/075 20130101; A61F 2/89 20130101; A61F 2/07 20130101;
A61F 2220/0058 20130101; A61F 2230/005 20130101 |
Class at
Publication: |
623/001.12 ;
623/001.13; 606/158 |
International
Class: |
A61F 2/84 20070101
A61F002/84; A61F 2/86 20070101 A61F002/86; A61B 17/122 20070101
A61B017/122; A61B 17/128 20070101 A61B017/128 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2003 |
IL |
158960 |
Claims
1. A medical implant, comprising: first and second ring members,
each comprising a resilient framework having a generally
cylindrical form; a tubular sleeve, fixed to the first and second
ring members so as to hold the ring members in mutual longitudinal
alignment, thereby defining a lumen passing through the ring
members; and a constricting element, which is fit around the sleeve
at a location intermediate the first and second ring members so as
to reduce a diameter of the lumen at the location.
2. The implant according to claim 1, wherein the framework
comprises a wire, which is bent in a serpentine form.
3. The implant according to claim 1, wherein the ring members are
adapted to be inserted in a radially-compressed form through a body
passage to a target position within the passage, and then to expand
radially at the target position so as to open the lumen
therethrough.
4. The implant according to claim 3, wherein the framework
comprises an elastic material, which is compressible to provide the
radially-compressed form of the ring members, and which expands
radially when released at the target position.
5. The implant according to claim 1, and comprising one or more
longitudinal support members, fixed to the framework of the first
and second ring members, alongside the sleeve, so as to join the
first and second ring members together.
6. The implant according to claim 1, wherein the sleeve comprises a
fabric.
7. The implant according to claim 6, wherein the fabric is stitched
to the framework of the first and second ring members.
8. The implant according to claim 1, wherein the lumen passing
through the first and second ring members has first and second
ends, and wherein the framework is configured to provide elongate
protrusions at one or more of the ends of the lumen.
9. The implant according to claim 8, wherein the sleeve is cut at
one or more of the first and second ends in conformance with the
protrusions.
10. The implant according to claim 9, wherein the sleeve is cut at
the first end in conformance with the protrusions, while the sleeve
at the second end covers both the protrusions and interstices
between the protrusions at the second end of the lumen.
11. The implant according to claim 1, wherein the implant is
adapted to be implanted in a coronary sinus of a patient, so that a
flow of blood through the coronary sinus is inhibited by the
reduced diameter of the lumen.
12. The implant according to claim 1, wherein the constricting
element is adapted to expand under an outward radial force so as to
permit the reduced diameter of the lumen to increase.
13. The implant according to claim 12, wherein the constricting
element comprises an elastic wire, having bends that are fastened
shut so as to provide the reduced diameter, and which are adapted
to open under the outward radial force.
14. A method for producing a medical implant, comprising: providing
first and second ring members, each comprising a resilient
framework having a generally cylindrical form; fixing a tubular
sleeve to the first and second ring members so as to hold the ring
members in mutual longitudinal alignment, thereby defining a lumen
passing through the ring members; and fitting a constricting
element around the sleeve at a location intermediate the first and
second ring members so as to reduce a diameter of the lumen at the
location.
15. The method according to claim 14, wherein providing the
framework comprises bending a wire into a serpentine form.
16. The method according to claim 15, wherein the lumen passing
through the first and second ring members has first and second
ends, and wherein bending the wire comprises producing elongate
protrusions of the framework at one or more of the ends of the
lumen.
17. The method according to claim 14, and comprising fixing one or
more longitudinal support members to the framework of the first and
second ring members, alongside the sleeve, so as to join the first
and second ring members together.
18. The method according to claim 14, wherein fixing the sleeve
comprises stitching a fabric to the framework of the first and
second ring members.
19. The method according to claim 14, wherein fitting the
constricting element comprises configuring the constricting element
to expand under an outward radial force so as to permit the reduced
diameter of the lumen to increase.
20. The method according to claim 19, wherein the constricting
element comprises an elastic wire, having bends that are fastened
shut so as to provide the reduced diameter, and which are adapted
to open under the outward radial force.
21. A method for restricting flow of a fluid through a body
passage, comprising: providing an implant comprising first and
second ring members, each comprising a resilient framework having a
generally cylindrical form, with a tubular sleeve, fixed to the
first and second ring members so as to hold the ring members in
mutual longitudinal alignment, thereby defining a lumen passing
through the ring members, and a constricting element fit around the
sleeve at a location intermediate the first and second ring members
so as to reduce a diameter of the lumen at the location; passing
the implant, in a radially-compressed form, through the body
passage to a target position within the body passage; and causing
the implant to expand radially at the target position so as to open
the lumen therethrough.
22. The method according to claim 21, wherein the framework
comprises an elastic material, which is compressible to provide the
radially-compressed form, and which expands radially when released
at the target position.
23. The method according to claim 21, wherein the lumen passing
through the first and second ring members has first and second
ends, and wherein the framework is configured to provide elongate
protrusions at one or more of the ends of the lumen, and wherein
causing the implant to expand comprises anchoring the implant in
the target position using the elongate protrusions.
24. The method according to claim 21, wherein the body passage is a
coronary sinus of a patient, and wherein the implant inhibits a
flow of blood through the coronary sinus due to the reduced
diameter of the lumen.
25. The method according to claim 21, wherein passing the implant
comprises enclosing the implant within a catheter, which passes
through the body passage, and wherein causing the implant to expand
comprises ejecting the implant through an aperture in a distal end
of the catheter.
26. The method according to claim 25, wherein the distal end of the
catheter has generally conical shape, and wherein ejecting the
implant comprises expanding the distal end so as to open the
aperture so that the implant may pass therethrough.
27. The method according to claim 25, wherein the distal end of the
catheter has generally conical shape, and wherein ejecting the
implant comprises tearing the distal end so as to open the aperture
so that the implant may pass therethrough.
28. The method according to claim 25, wherein the distal end of the
catheter comprises an elastic plug, which closes the aperture while
the catheter passes through the body passage, and wherein ejecting
the implant comprises radially compressing the plug so as to open
the aperture and to allow the lumen of the implant to pass over the
plug.
29. The method according to claim 21, and comprising exerting an
outward radial pressure from within the implant after the implant
has expanded in the target position so as to open the constricting
element, thereby permitting the reduced diameter of the lumen to
increase.
30. The method according to claim 29, wherein exerting the outward
radial pressure comprises inserting a balloon into the lumen, and
inflating the balloon.
31. Apparatus for delivery of an implant to a target position in a
body passage, the apparatus comprising: an elongate, tubular
sheath, which is adapted to be passed through the body passage
while containing the implant in a compressed state inside the
sheath, wherein the sheath has a distal end made of an elastic
material in a generally conical shape with an aperture formed
therein; and an ejector, which is adapted to force the implant in a
distal direction, thus stretching the elastic material so as to
expand the aperture, whereby the implant passes through the
aperture.
32. Apparatus for delivery of an implant to a target position in a
body passage, the apparatus comprising: an elongate, tubular
sheath, which is adapted to be passed through the body passage
while containing the implant in a compressed state inside the
sheath, wherein the sheath has a distal end having a generally
conical shape with an aperture formed therein; and an ejector,
which is adapted to force the implant in a distal direction, thus
causing the distal end of the sheath to tear so as to expand the
aperture, whereby the implant passes through the aperture.
33. The apparatus according to claim 32, wherein the distal end of
the sheath is scored with lines, along which the sheath tears.
34. Apparatus for delivery of an implant to a target position in a
body passage, the apparatus comprising: an elongate, tubular
sheath, which is adapted to be passed through the body passage
while containing the implant in a compressed state inside the
sheath, wherein the sheath has a distal end with an aperture formed
therein; a lumen passing longitudinally through the sheath and
through the implant contained within the sheath, such that a
portion of the lumen at the distal end of the sheath is distended
so as to plug the aperture while the sheath passes through the body
passage, the distended portion of the lumen comprising a flexible
material; and an ejector, which is adapted to force the implant in
a distal direction, thus ejecting the implant through the aperture
and compressing the distended portion of the lumen, so that the
implant passes over the lumen to the target position in the body
passage.
35. Apparatus for narrowing a body passage, the apparatus
comprising: a narrowing implant, which comprises: first and second
ring members, each comprising a resilient framework having a
generally cylindrical form; a tubular sleeve, fixed to the first
and second ring members so as to hold the ring members in mutual
longitudinal alignment, thereby defining a lumen passing through
the ring members; and a constricting element, which is fit around
the sleeve at a location intermediate the first and second ring
members so as to reduce a diameter of the lumen at the location;
and catheter for delivering the implant to a target position in the
body passage.
36. The apparatus according to claim 35, wherein the catheter
comprises: an elongate, tubular sheath, which is adapted to be
passed through the body passage while containing the implant in a
compressed state inside the sheath, wherein the sheath has a distal
end having a generally conical shape with an aperture formed
therein; and an ejector, which is adapted to force the implant in a
distal direction, thus stretching the elastic material so as to
expand the aperture, whereby the implant passes through the
aperture and is implanted at the target position.
37. The apparatus according to claim 35, wherein the catheter
comprises: an elongate, tubular sheath, which is adapted to be
passed through the body passage while containing the implant in a
compressed state inside the sheath, wherein the sheath has a distal
end having a generally conical shape with an aperture formed
therein; and an ejector, which is adapted to force the implant in a
distal direction, thus causing the distal end of the sheath to tear
so as to expand the aperture, whereby the implant passes through
the aperture and is implanted at the target position.
38. The apparatus according to claim 35, wherein the catheter
comprises: an elongate, tubular sheath, which is adapted to be
passed through the body passage while containing the implant in a
compressed state inside the sheath, wherein the sheath has a distal
end with an aperture formed therein; a lumen passing longitudinally
through the sheath and through the implant contained within the
sheath, such that a portion of the lumen at the distal end of the
sheath is distended so as to plug the aperture while the sheath
passes through the body passage, the distended portion of the lumen
comprising a flexible material; and an ejector, which is adapted to
force the implant in a distal direction, thus ejecting the implant
through the aperture and compressing the distended portion of the
lumen, so that the implant passes over the lumen to the target
position in the body passage.
39. A stent for implantation in a lumen, comprising: a plurality of
struts, with intervening openings therebetween; and narrow
connecting pieces, bridging at least some of the openings so as to
interconnect the struts, wherein exertion of a first outward radial
force on the struts causes the stent to open to a first diameter by
opening the intervening openings between the struts, and wherein
the narrow connecting pieces are adapted to break under exertion on
the struts of a second outward radial force, greater than the first
outward radial force, so that the stent opens to a second diameter,
greater than the first diameter.
40. A method for narrowing a blood vessel, comprising: inserting a
catheter into the blood vessel; deploying a clip outward from the
catheter so that first and second ends of the clip engage
respective first and second points on a wall of the blood vessel;
and ejecting the clip from the catheter after the first and second
ends of the clip have engaged the first and second points, thus
causing the ends of the clip to draw toward one another and thereby
pinching together the first and second points.
41. The method according to claim 29, wherein exerting the outward
radial pressure comprises controlling the pressure so as to
determine a target diameter to which the lumen is to increase.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to implantable
therapeutic devices, and specifically to intravascular
implants.
BACKGROUND OF THE INVENTION
[0002] Stent implants are commonly used in treating arterial
stenoses and other unwanted constrictions of body passages. Stents
typically comprise a metal coil or mesh. An arterial stent, for
example, is threaded through the vascular system to the point of
stenosis in an artery. When the stent is in place, it is expanded
to force the artery open to the desired diameter.
[0003] On the other hand, there are some procedures in which stent
implants are required to constrict the diameter of a blood vessel.
For example, Ruiz describes an endoluminal stent having adjustable
constriction in U.S. Pat. No. 6,120,534, whose disclosure is
incorporated herein by reference. The stent comprises a deformable
mesh having a conical portion and a constricted region, which forms
a flow-limiting constriction. The stent is delivered and deployed
inside a blood vessel. The constricted region of the mesh is then
selectively enlarged to adjust the flow impedance in the vessel.
Ruiz describes particularly the use of his stent to reduce blood
flow in the pulmonary artery, as a palliative treatment for infants
having complex congenital cardiac malformations.
[0004] Other types of constricting stents and applications of such
stents are described by Shalev et al. in PCT Patent Publication WO
01/2239, whose disclosure is incorporated herein by reference. In
particular, this publication describes the use of a flow-reducing
implant in the coronary sinus, in order to promote angiogenesis in
the heart tissues. The implant is inserted by catheter through a
central vein, such as the jugular vein and brought into the
coronary sinus. Alternatively, the implant may be installed in one
or more of the coronary veins. Once the implant is in place, it is
allowed to elastically expand or is plastically expanded using a
balloon.
SUMMARY OF THE INVENTION
[0005] Embodiments of the present invention provide a constricting
implant that is simple and inexpensive to manufacture, and can be
deployed easily in the blood vessels, as well as in other body
passages. The implant comprises a pair of generally-cylindrical
ring members, which are fixed to a tubular sleeve so as to define a
lumen passing through the ring members and the sleeve. The ring
members each comprise a framework made of a resilient material,
which can be compressed while the implant is inserted into the
desired location in the blood vessel, and then expands either
elastically or plastically to roughly the full diameter of the
vessel. The sleeve comprises a flexible material, such as a fabric.
The ring members are positioned longitudinally along the sleeve so
that there is a longitudinal gap in between the two ring members. A
constricting element is fitted around the sleeve in this gap so as
to reduce the diameter of the lumen in between the two ring members
to less than the diameter of the vessel.
[0006] Thus, when the implant is inserted into the vessel (or other
body passage), the ring members expand, along with the portion of
the sleeve to which they are fixed. The part of the sleeve in the
gap between the ring members, however, remains constricted due to
the constricting element. This constricted area of the lumen
typically reduces the flow of blood through the vessel. The implant
is particularly useful for restricting blood flow in the coronary
sinus, as described in the above-mentioned PCT publication, but it
may similarly be used in other veins and arteries, as well as in
other medical applications. In some embodiments, the constricting
element may be opened in situ within the blood vessel, so as permit
the diameter of the implant to increase if and when the
constriction is no longer desired.
[0007] There is therefore provided, in accordance with an
embodiment of the present invention, a medical implant,
including:
[0008] first and second ring members, each including a resilient
framework having a generally cylindrical form;
[0009] a tubular sleeve, fixed to the first and second ring members
so as to hold the ring members in mutual longitudinal alignment,
thereby defining a lumen passing through the ring members; and
[0010] a constricting element, which is fit around the sleeve at a
location intermediate the first and second ring members so as to
reduce a diameter of the lumen at the location.
[0011] The framework may include a wire, which is bent in a
serpentine form. Typically, the ring members are adapted to be
inserted in a radially-compressed form through a body passage to a
target position within the passage, and then to expand radially at
the target position so as to open the lumen therethrough. The
framework may include an elastic material, which is compressible to
provide the radially-compressed form of the ring members, and which
expands radially when released at the target position.
[0012] In one embodiment, the implant includes one or more
longitudinal support members, fixed to the framework of the first
and second ring members, alongside the sleeve, so as to join the
first and second ring members together.
[0013] In a further embodiment, the sleeve includes a fabric, which
is stitched to the framework of the first and second ring
members.
[0014] In another embodiment, the lumen passing through the first
and second ring members has first and second ends, and the
framework is configured to provide elongate protrusions at one or
more of the ends of the lumen. The sleeve may be cut at one or more
of the first and second ends in conformance with the protrusions.
For example, the sleeve may be cut at the first end in conformance
with the protrusions, while the sleeve at the second end covers
both the protrusions and interstices between the protrusions at the
second end of the lumen.
[0015] The implant may be adapted to be implanted in a coronary
sinus of a patient, so that a flow of blood through the coronary
sinus is inhibited by the reduced diameter of the lumen.
[0016] In another aspect of the invention, the constricting element
is adapted to expand under an outward radial force so as to permit
the reduced diameter of the lumen to increase. In one embodiment,
the constricting element includes an elastic wire, having bends
that are fastened shut so as to provide the reduced diameter, and
which are adapted to open under the outward radial force.
[0017] There is also provided, in accordance with an embodiment of
the present invention, a method for producing a medical implant,
including:
[0018] providing first and second ring members, each including a
resilient framework having a generally cylindrical form;
[0019] fixing a tubular sleeve to the first and second ring members
so as to hold the ring members in mutual longitudinal alignment,
thereby defining a lumen passing through the ring members; and
[0020] fitting a constricting element around the sleeve at a
location intermediate the first and second ring members so as to
reduce a diameter of the lumen at the location.
[0021] There is additionally provided, in accordance with an
embodiment of the present invention, a method for restricting flow
of a fluid through a body passage, including:
[0022] providing an implant including first and second ring
members, each including a resilient framework having a generally
cylindrical form, with a tubular sleeve, fixed to the first and
second ring members so as to hold the ring members in mutual
longitudinal alignment, thereby defining a lumen passing through
the ring members, and a constricting element fit around the sleeve
at a location intermediate the first and second ring members so as
to reduce a diameter of the lumen at the location;
[0023] passing the implant, in a radially-compressed form, through
the body passage to a target position within the body passage;
and
[0024] causing the implant to expand radially at the target
position so as to open the lumen therethrough.
[0025] Typically, passing the implant includes enclosing the
implant within a catheter, which passes through the body passage,
and causing the implant to expand includes ejecting the implant
through an aperture in a distal end of the catheter. In some
embodiments, the distal end of the catheter has generally conical
shape, and ejecting the implant includes expanding the distal end
so as to open the aperture so that the implant may pass
therethrough. Alternatively, ejecting the implant includes tearing
the distal end so as to open the aperture so that the implant may
pass therethrough. Further alternatively, the distal end of the
catheter includes an elastic plug, which closes the aperture while
the catheter passes through the body passage, and ejecting the
implant includes radially compressing the plug so as to open the
aperture and to allow the lumen of the implant to pass over the
plug.
[0026] In another aspect of the invention, the method includes
exerting an outward radial pressure from within the implant after
the implant has expanded in the target position so, as, to open the
constricting element, thereby permitting the reduced diameter of
the lumen to increase. Typically, exerting the outward radial
pressure includes inserting a balloon into the lumen, and inflating
the balloon.
[0027] There is further provided, in accordance with an embodiment
of the present invention, apparatus for delivery of an implant to a
target position in a body passage, the apparatus including:
[0028] an elongate, tubular sheath, which is adapted to be passed
through the body passage while containing the implant in a
compressed state inside the sheath, wherein the sheath has a distal
end made of an elastic material in a generally conical shape with
an aperture formed therein; and
[0029] an ejector, which is adapted to force the implant in a
distal direction, thus stretching the elastic material so as to
expand the aperture, whereby the implant passes through the
aperture.
[0030] There is moreover provided, in accordance with an embodiment
of the present invention, apparatus for delivery of an implant to a
target position in a body passage, the apparatus including:
[0031] an elongate, tubular sheath, which is adapted to be passed
through the body passage while containing the implant in a
compressed state inside the sheath, wherein the sheath has a distal
end having a generally conical shape with an aperture formed
therein; and
[0032] an ejector, which is adapted to force the implant in a
distal direction, thus causing the distal end of the sheath to tear
so as to expand the aperture, whereby the implant passes through
the aperture.
[0033] The distal end of the sheath may be scored with lines, along
which the sheath tears.
[0034] There is furthermore provided, in accordance with an
embodiment of the present invention, apparatus for delivery of an
implant to a target position in a body passage, the apparatus
including:
[0035] an elongate, tubular sheath, which is adapted to be passed
through the body passage while containing the implant in a
compressed state inside the sheath, wherein the sheath has a distal
end with an aperture formed therein;
[0036] a lumen passing longitudinally through the sheath and
through the implant contained within the sheath, such that a
portion of the lumen at the distal end of the sheath is distended
so as to plug the aperture while the sheath passes through the body
passage, the distended portion of the lumen including a flexible
material; and
[0037] an ejector, which is adapted to force the implant in a
distal direction, thus ejecting the implant through the aperture
and compressing the distended portion of the lumen, so that the
implant passes over the lumen to the target position in the body
passage.
[0038] There is also provided, in accordance with an embodiment of
the present invention, apparatus for narrowing a body passage, the
apparatus including:
[0039] a narrowing implant, which includes:
[0040] first and second ring members, each including a resilient
framework having a generally cylindrical form;
[0041] a tubular sleeve, fixed to the first and second ring members
so as to hold the ring members in mutual longitudinal alignment,
thereby defining a lumen passing through the ring members; and
[0042] a constricting element, which is fit around the sleeve at a
location intermediate the first and second ring members so as to
reduce a diameter of the lumen at the location; and
[0043] a catheter for delivering the implant to a target position
in the body passage.
[0044] There is additionally provided, in accordance with an
embodiment of the present invention, a stent for implantation in a
lumen, including:
[0045] a plurality of struts, with intervening openings
therebetween; and
[0046] narrow connecting pieces, bridging at least some of the
openings so as to interconnect the struts,
[0047] wherein exertion of a first outward radial force on the
struts causes the stent to open to a first diameter by opening the
intervening openings between the struts, and
[0048] wherein the narrow connecting pieces are adapted to break
under exertion on the struts of a second, outward radial force,
greater than the first outward radial force, so that the stent
opens to a second diameter, greater than the first diameter.
[0049] There is further provided, in accordance with an embodiment
of the present invention, a method for narrowing a blood vessel,
including:
[0050] inserting a catheter into the blood vessel;
[0051] deploying a clip outward from the catheter so that first and
second ends of the clip engage respective first and second points
on a wall of the blood vessel; and
[0052] ejecting the clip from the catheter after the first and
second ends of the clip have engaged the first and second points,
thus causing the ends of the clip to draw toward one another and
thereby pinching together the first and second points.
[0053] The present invention will be more fully understood from the
following detailed description of the embodiments thereof, taken
together with the drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
[0054] FIG. 1 is a schematic, pictorial view of an implantable
device for restricting flow in a blood vessel, in accordance with
an embodiment of the present invention;
[0055] FIG. 2 is a schematic, cross-sectional view of the device of
FIG. 1, taken `along` a line II-II;
[0056] FIG. 3 is a schematic side view of the device of FIG. 1
implanted in a blood vessel;
[0057] FIG. 4 is a schematic side view of a device for restricting
flow, implanted in a blood vessel, in accordance with another
embodiment of the present invention;
[0058] FIG. 5 is a schematic, pictorial view of an implantable
device for restricting flow in a blood vessel, in accordance with
still another embodiment of the present invention;
[0059] FIGS. 6A and 6B are schematic side views of a catheter used
to deliver an implantable device to a target location in a blood
vessel, in accordance with an embodiment of the present
invention;
[0060] FIGS. 7A and 7B are schematic side views of a catheter used
to deliver an implantable device to a target location in a blood
vessel, in accordance with another embodiment of the present
invention;
[0061] FIGS. 8A, 8B and 8C are schematic side views of a catheter
used to deliver an implantable device to a target location in a
blood vessel, in accordance with yet another embodiment of the
present invention;
[0062] FIG. 9A is a schematic, pictorial illustration of a
constricting ring, in accordance with an embodiment of the present
invention;
[0063] FIGS. 9B and 9C are schematic side views showing details of
a constricting ring, in accordance with embodiments of the present
invention;
[0064] FIG. 10 is a schematic, pictorial illustration of a
constricting ring that has been opened, in accordance with an
embodiment of the present invention;
[0065] FIG. 11 is a schematic, detail view of a stent, in
accordance with an alternative embodiment of the present
invention;
[0066] FIG. 12 is a schematic side view of a vascular structure, in
which a catheter is inserted for deployment of a constricting clip,
in accordance with an embodiment of the present invention; and
[0067] FIGS. 13A-C are schematic, sectional views of the vascular
structure of FIG. 12, taken along a line XIII-XIII in FIG. 12,
showing stages in the deployment of a constricting clip, in
accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
[0068] Reference is now made to FIGS. 1 and 2, which schematically
illustrate a device 20 for implantation in a body passage, in
accordance with an embodiment of the present invention. FIG. 1 is a
pictorial illustration of the device, while FIG. 2 is a
cross-sectional view taken along a line II-II in FIG. 1. Device 20
is adapted for use particularly in restricting blood flow through
the coronary sinus, as described in the above-mentioned PCT
Publication WO 01/72239. Alternatively, devices in accordance with
the principles of the present invention may be implanted elsewhere
in the vascular system, as well as in other body passages. For the
sake of simplicity and clarity, however, and not limitation,
embodiments of the present invention are described hereinbelow with
reference to implantation of flow-constricting devices in blood
vessels, such as the coronary sinus.
[0069] Device 20 comprises ring elements 22 and 24, each of which
comprises a resilient framework 26. Each framework defines a
generally-cylindrical shape, although this shape is distorted by
the mechanical constraints of the device, as described below.
Therefore, the cylinders tend to widen at the ends of device 20 and
narrow toward the middle, as shown in FIG. 1. In the pictured
embodiments, framework 26 comprises a wire or thin rod, which is
bent into a serpentine shape. Typically, the framework comprises an
elastic material, which may be compressed or otherwise bent, but
then returns to its original shape, as shown in the figure.
Super-elastic materials, such as Nitinol, are useful for this
purpose. Alternatively, the framework may comprise a resilient,
deformable material, such as a suitable metal or plastic. Further
alternatively or additionally, each framework 26 may comprise a
mesh or coil, as is known in the art. In any case, the term
"resilient" as used herein means that once device 20 is deployed
within a body passage, framework 26 has sufficient mechanical
strength to withstand normal forces exerted by the wall of the
passage and by fluid flow within the passage, in the manner of
stents known in the art.
[0070] Ring elements 22 and 24 are fixed to a flexible sleeve 28,
which has a generally tubular form. Typically, sleeve 28 comprises
a biocompatible fabric, such as Gore-Tex or Dacron, which is
stitched or otherwise fastened to framework 26. Alternatively,
other sleeve materials may be used, such as thin plastic or rubber
materials. The sleeve is fixed to the ring elements in such a way
as to form a lumen 32 (FIG. 2) through device 20. The sleeve is
supported at each end of the lumen by one of the ring elements,
while leaving a longitudinal gap in the sleeve, typically several
millimeters long, between the inner ends of the two ring elements.
While the ring elements themselves are relatively stiff (due to the
resilience of framework 26), device 20 can be bent and deformed
freely within the gap region of the sleeve.
[0071] A constricting element 30 is fitted around sleeve 28 within
the gap region. As can be seen in FIG. 2, the effect of this
constricting element is to reduce the diameter of lumen 32 to a
predetermined size, less than the expanded diameter of ring
elements 22 and 24. Constricting element 30 may simply comprise a
thread, which is tied around the sleeve, or it may alternatively
comprise a closed ring, made of plastic or metal. A constricting
ring of this latter type is shown in FIG. 9A and described
hereinbelow with reference thereto.
[0072] FIG. 3 is a schematic side view of device 20 after
implantation inside a blood vessel 40. Typically, device 20 is
passed through the vascular system to the appropriate location
(such as the coronary sinus), using a suitable percutaneous
catheter (not shown in the figures). Suitable methods of
catheterization for this purpose are known in the art. During the
insertion procedure, device 20 is compressed radially, so that its
outer diameter is substantially smaller than the blood vessels
through which it must pass. As noted above, device 20 is able to
bend freely in the area of the gap between ring elements 22 and 24,
where constricting element 30 is located. This bending capability
generally makes it easier for the physician operating the catheter
to pass the device through bends in the blood vessels.
[0073] Upon reaching the desired location in blood vessel 40,
device 20 is released from the catheter. If framework 26 is made of
an elastic material, such as Nitinol, the device will expand by
itself, due to its own elasticity, as soon as it is released.
Alternatively, if framework 26 comprises a malleable material, a
balloon may be inflated within each of ring elements 22 and 24, or
other means known in the art may be used, in order to expand the
framework. The above-mentioned PCT publication describes special
types of balloons that may be used for this purpose. As can be seen
in FIGS. 1 and 3, the serpentine shape of framework 26 creates
elongated "fingers" that protrude at the ends of device 20. Once
the ring elements have expanded, these fingers press outward
against the wall of the blood vessel, thus anchoring device 20 in
place. Blood in vessel 40 flows through lumen 32, but flow is
restricted by the constriction at constricting element 30. If
device 2Q is deployed in the coronary sinus, for example, the flow
restriction causes increased pressure in the coronary veins, thus
promoting myocardial angiogenesis.
[0074] Device 20 may be left in place indefinitely, in
substantially the form shown in FIG. 3. Alternatively, it may be
desirable in some cases to eliminate the flow restriction caused,
by the device. In such cases, it is not necessary to remove device
20 from the body. Rather, a catheter with a suitable cutting tool
may be inserted percutaneously to the location of the device, and
the cutting tool may then be used to cut constricting element 30.
The constriction in the diameter of lumen 32 will then open up by
itself.
[0075] FIG. 4 is a schematic side view of an implantable device 50
after implantation inside blood vessel 40, in accordance with
another embodiment of the present invention. Blood in vessel 40 is
assumed to flow from left to right in the view of the figure.
Device 50 is substantially identical to device 20, as described
above, except for the shape of sleeve 28. In device 20, sleeve 28
is trimmed so that the ends of the sleeve have the same general
shape as the "fingers" of framework 26. In device 50, however,
sleeve 28 is trimmed to a generally straight edge at the upstream
(left) end of the device, covering the interstices between the
fingers, as well as the fingers themselves. The straight upstream
edge can be useful in reducing blood leakage around the sides of
the device, thus providing more complete and reliable flow
restriction. The uneven shape of the sleeve is maintained on the
downstream edge, in order to anchor device 50 securely to the walls
of vessel 40 against the pressure exerted by the blood flow in the
vessel. Alternatively, sleeve 28 may be cut in other
configurations, as mandated by medical and mechanical
considerations.
[0076] FIG. 5 is a schematic, pictorial view of an implantable
device 60, in accordance with still another embodiment of the
present invention. Device 60 is also substantially similar to
device 20, as described above, except for the addition of
longitudinal support members 62 and 65. The support members join
ring elements 22 and 24 together and thus enhance the mechanical
strength and stability of device 60. Although two longitudinal
support members are shown in FIG. 5, greater or smaller numbers of
supports members may be used in like fashion. Note, however, that
in the gap between the ring elements, sleeve 28 is detached from
the support members, so that the diameter of lumen 32 can still be
reduced by constricting element 30.
[0077] FIGS. 6A and 6B are schematic side views of a catheter 70,
in a cutaway view, which is used to deliver device 20 to a target
position in blood vessel 40, in accordance with an embodiment of
the present invention. As shown in FIG. 6A, catheter 70 has a
tubular outer shell 72 and a central lumen 74. Prior to delivery,
device 20 is held inside shell 70, with lumen 74 passing through
lumen 32 of device 20. A distal end 76 of shell 72 has a roughly
conical shape, and has a small exit aperture 78 surrounding lumen
32.
[0078] Typically, to implant device 20 in vessel 40, an operator
threads a guide wire 80 through a part of the patient's vascular
system to the target position, as is known in the art. For example,
the guide wire may be passed through the jugular vein into the
coronary sinus. Once the guide wire is in place, the operator
slides lumen 74 over the guide wire, and thus guides distal end 76
of catheter 70 to the target position. A contrast medium may be
injected through lumen 74 or through another, parallel lumen (not
shown) to aid the operator in visualizing vessel 40 during the
procedure using a fluoroscope, as is known in the art.
[0079] When distal end 76 has reached the target position, the
operator uses an ejector 82 to push device 20 out through aperture
78 in the distal end of the catheter. Distal end 76 in this
embodiment is made of a material that is sufficiently elastic so
that the aperture opens freely to the diameter of device 20. Once
the device is ejected, it expands to the diameter of vessel 40, as
shown in FIG. 3, and anchors itself in place. The operator then
withdraws catheter 70, and distal end 76 contracts back roughly to
its original form.
[0080] FIGS. 7A and 7B are schematic side views of another catheter
90, which is used to deliver device 20, in accordance with an
alternative embodiment of the present invention. FIG. 7A shows the
catheter before delivery of device 20, while FIG. 7B shows the
catheter after, the delivery. In this embodiment, distal end 76
comprises a thin sheath, which tears open as ejector 82 pushes the
device out of the catheter. Optionally, as shown in FIG. 7A, the
distal end is scored along lines 92, so that as device 20 is
ejected, the distal end tears cleanly, in a predictable fashion.
Once device 20 has been ejected, the distal end may remain open
where it has torn, but the open distal does not interfere with
withdrawal of catheter 90 along wire 80.
[0081] FIGS. 8A, 8B and 8C are schematic side views of a catheter
100 for delivering device 20, in accordance with yet another
embodiment of the present invention. In this embodiment, distal end
76 has an aperture 102 that is large enough to accommodate the
(compressed) diameter of device 20 when the device is ejected from
the catheter. Until the catheter reaches the target position,
however, the aperture is closed by a distended portion 104 of a
lumen 106 that passes through the catheter, as shown in FIG. 8A.
The lumen is typically used to accommodate a guide wire and/or to
inject contrast medium, as described above. Distended portion 104
is made of a flexible material, which may be either elastic or
malleable, and is shaped so as to plug aperture 102.
[0082] When distal end 76 reaches the target position, lumen 106 is
advanced (and/or catheter 100 is withdrawn) so as to open aperture
102, as shown in FIG. 8B. Ejector 82 then pushes device 20 out
through the aperture. As shown in FIG. 8C, portion 104 is
sufficiently flexible so that as the narrow, gap region of lumen 32
through device 20 passes over it, portion 104 closes down so that
lumen 32 can slide over it. Once device 20 has been implanted at
the target position, portion 104 resumes its previous shape, and
lumen 106 may be pulled back in the proximal direction in order to
close aperture 102. Catheter 100 is then withdrawn from the
body.
[0083] FIG. 9A is a schematic, pictorial illustration of a
constricting ring 120, in accordance with an embodiment of the
present invention. This ring may be used as a constricting element
in device 20, taking the place of element 30 shown in the preceding
figures. Ring 120 comprises a flexible, elastic wire 122. For
example, wire 122 may comprise a super-elastic material, such as
Nitinol. Wire 122 is formed with multiple bends, typically in a
serpentine pattern, as shown in FIG. 9A. Some of the bends are
closed bends 124, at which the wire segments on opposing sides of
the bend are fixed together, thus narrowing the overall
circumference of ring 120. When ring 120 is installed in place of
element 30 on device 20, the narrowed circumference of the ring
constricts the diameter of lumen 32, as shown in FIGS. 1 and 2.
[0084] FIGS. 9B and 9C are schematic, detail views of one of closed
bends 124 in ring 120, in accordance with two exemplary embodiments
of the present invention. In the embodiment of FIG. 9B, the
opposing segments of wire 122 are pulled together and then fastened
by welding, glue or other means, at a fastening point 126. Laser
micro-welding, as is known in the art, may be used for this
purpose. In FIG. 9C, a connecting element 128, such as a miniature
ring, is welded or otherwise fastened in place between the segments
of wire on either side of the bend. In either case, bends 124 are
typically closed weakly enough so that the fastening points or
connecting elements will break open under outward radial
pressure.
[0085] FIG. 10 is a schematic, pictorial illustration of ring 120
following opening of closed bends 124, in accordance with an
embodiment of the present invention. The closed bends may be opened
in situ, after device 20 has been implanted in a blood vessel. For
this purpose, for example, a balloon catheter may be inserted into
lumen 32 of device 20, and the balloon may be inflated with
sufficient pressure to break open the fastening points of at least
some of bends 124. Due to the elasticity of wire 122, ring 120 will
then expand to the larger diameter shown in FIG. 10, and lumen 32
will open up accordingly. This sort of procedure may be used, for
example, to permit free flow of blood through vessel 40 when the
constriction due to device 20 is no longer needed or desired.
[0086] FIG. 11 is a schematic, detail view of a part of a stent
130, in accordance with another embodiment of the present
invention. This embodiment also uses the principle of radial
expansion of an intravascular implant that was described above.
Stent 130 comprises a structure of struts 132 with intervening
openings 134. Some of the openings are bridged by narrow connecting
pieces 136. Stent 130 is initially collapsed and crimped over a
balloon for insertion into the target blood vessel. Inflation of
the balloon to a first, intermediate pressure causes the stent to
expand radially outward, so that openings 134 between struts 132
open to the configuration shown in FIG. 11. The balloon is then
withdrawn. The stent may be used in this configuration, for
example, to open a blocked artery or other body lumen.
[0087] It often occurs after implantation of a stent that the body
lumen in question once again becomes constricted, due to accretion
of material inside the stent, for example. In this case, a balloon
may once more be inserted inside stent 130 and inflated to a
second, higher pressure. The balloon thus exerts an outward radial
force on stent 130, causing one or more of connecting pieces 136 to
break open. Thus, the diameter of stent 130 (and of the lumen it is
supporting) is increased simply and safely.
[0088] Although in the embodiments described above, framework 26
and sleeve 28 are shown to have certain particular shapes,
alternative shapes and forms of these elements, which will be
apparent to those skilled in the art, are considered to be within
the scope of the present invention. Similarly, catheters of the
general types described above may be used to deliver not only
device 20, but also other implantable devices as described
hereinabove and as are otherwise known in the art. On the other
hand, although the catheters shown here provide convenient means
for delivering implants in accordance with the present invention,
such implants may also be delivered by other means, both minimally
invasive (typically percutaneous) and invasive (i.e.,
surgical).
[0089] Methods for reducing the diameter or circumference of a
vascular structure by surgical means are also known in the art.
Methods of this sort are described, for example, in. U.S. Pat. No.
5,593,424 and U.S. Pat. No. 6,561,969, whose disclosure are
incorporated herein by reference. These methods generally require
suturing of the vascular tissue, which can be difficult and
time-consuming to carry out.
[0090] In contrast to these methods and to the preceding
embodiments, FIG. 12 schematically illustrates a method for
constricting the diameter of a vascular structure without the use
of sutures or a stent, in accordance with an alternative embodiment
of the present invention. The embodiment is illustrated here with
reference to reducing the diameter of a coronary sinus 140 of a
patient, although this method is also applicable to other vascular
structures. A catheter 142 is inserted through a right atrium 144
of the patient into coronary sinus 140. The catheter is bent at its
distal end, as shown in the figure, to permit convenient deployment
of a constricting clip 146, as described below.
[0091] FIGS. 13A-C are schematic, sectional views of coronary sinus
140, taken along a line XIII-XIII in FIG. 12, showing stages in the
deployment of clip 146, in accordance with an embodiment of the
present invention. Clip 146 typically comprises a super-elastic
material, which is formed so that in its relaxed state, it has an
approximately closed form, as shown in FIG. 13C, for example.
During insertion of catheter 142 into the coronary sinus, however,
clip 146 is compressed within the distal end of catheter 142, as
shown in FIG. 13A.
[0092] Once catheter 142 has been advanced into coronary sinus 140,
a deployment mechanism, such as a pusher (not shown) inside the
catheter, is actuated in order to advance clip 146 out of the
distal end of the catheter. As a result, the clip opens up into the
configuration shown in FIG. 13B. Ends 148 of the clip catch the
tissue of coronary sinus 140 at two points that are spaced apart on
the wall of the coronary sinus. The elasticity of clip 146 causes
the ends of the clip to draw together as the clip is advanced
further out of the catheter, as illustrated by arrows 150. Finally,
when the clip has advanced completely out of the end of the
catheter, ends 148 close in toward one another and pinch together
the portion of the vascular tissue that is located between the clip
ends. The result, as seen in FIG. 13C, is that the effective
diameter of coronary sinus 140 is reduced.
[0093] It will thus be appreciated that the embodiments described
above are cited by way of example, and 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 which would occur to persons skilled in the art upon
reading the foregoing description and which are not disclosed in
the prior art.
* * * * *