U.S. patent application number 10/957079 was filed with the patent office on 2005-12-29 for devices and methods for controlling expandable prosthesis during develoyment.
This patent application is currently assigned to Xtent, Inc.. Invention is credited to Demarais, Denise, Grainger, Jeffry J., Karratt, Joseph, Snow, David W..
Application Number | 20050288764 10/957079 |
Document ID | / |
Family ID | 35507044 |
Filed Date | 2005-12-29 |
United States Patent
Application |
20050288764 |
Kind Code |
A1 |
Snow, David W. ; et
al. |
December 29, 2005 |
Devices and methods for controlling expandable prosthesis during
develoyment
Abstract
Prosthesis delivery devices and methods are provided that enable
precise control of prosthesis position during deployment. The
prosthesis delivery devices may carry multiple prostheses and
include deployment mechanisms for delivery of a selectable number
of prostheses. Control mechanisms are provided in the prosthesis
delivery devices that control either or both of the axial and
rotational positions of the prostheses during deployment. This
enables the deployment of multiple prostheses at a target site with
precision and predictability, eliminating excessive spacing or
overlap between prostheses. In particular embodiments, the
prostheses of the invention are deployed in stenotic lesions in
coronary or peripheral arteries, or in other vascular
locations.
Inventors: |
Snow, David W.; (Menlo Park,
CA) ; Karratt, Joseph; (Millbrae, CA) ;
Grainger, Jeffry J.; (Portola Valley, CA) ; Demarais,
Denise; (Los Gatos, CA) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Assignee: |
Xtent, Inc.
Menlo Park
CA
|
Family ID: |
35507044 |
Appl. No.: |
10/957079 |
Filed: |
September 30, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10957079 |
Sep 30, 2004 |
|
|
|
10879949 |
Jun 28, 2004 |
|
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Current U.S.
Class: |
623/1.11 |
Current CPC
Class: |
A61F 2002/9511 20130101;
A61F 2002/9665 20130101; A61F 2/958 20130101; A61F 2/95 20130101;
A61F 2/97 20130101; A61F 2002/826 20130101; A61F 2002/9583
20130101; A61F 2/966 20130101; A61F 2002/9505 20130101 |
Class at
Publication: |
623/001.11 |
International
Class: |
A61F 002/06 |
Claims
What is claimed is:
1. A prosthesis delivery catheter comprising: an outer shaft
forming a first lumen; a plurality of self-expanding tubular
prostheses carried within the first lumen, the prostheses being
adapted to radially expand upon deployment from the first lumen;
and a movable coil member interactive with the prostheses to
control expansion of the prostheses when the prostheses are
deployed from the first lumen.
2. The prosthesis delivery catheter of claim 1, wherein the coil
member is removable from the deployed prostheses by rotating the
coil member.
3. The prosthesis delivery catheter of claim 1, wherein the
prostheses have sidewalls with a plurality of openings, the coil
member being threaded through the openings.
4. The prosthesis delivery catheter of claim 1, wherein the
prostheses comprise a plurality of struts, at least one of the
struts being bent inwardly, the coil member being threaded through
the inwardly bent struts.
5. The prosthesis delivery catheter of claim 1, wherein the coil
member is radially expandable to allow controlled expansion of the
prostheses.
6. The prosthesis delivery catheter of claim 3, wherein a distal
portion of the coil member is retractable into the outer shaft
following deployment of the selected number of prostheses.
7. The prosthesis delivery catheter of claim 1, wherein the
prostheses are disposed within the coil member.
8. The prosthesis delivery catheter of claim 1, wherein the coil
member comprises a plurality of loops forming a helix.
9. The prosthesis delivery catheter of claim 8, wherein between 2
and 6 loops are disposed in each prosthesis.
10. The prosthesis delivery catheter of claim 8, wherein more than
6 loops are disposed in each prosthesis.
11. The prosthesis delivery catheter of claim 1, wherein the coil
member comprises a plurality of loops contacting each other to form
a continuous tube.
12. The prosthesis delivery catheter of claim 1, further comprising
a deployment mechanism for deploying a selected number of
prostheses from the inner lumen.
13. The prosthesis delivery catheter of claim 12, wherein the
deployment mechanism comprises a pushing element slidably disposed
in the first lumen, the pushing element being in engagement with at
least one of the prostheses to advance the prostheses distally
relative to the outer shaft.
14. The prosthesis delivery catheter of claim 13, wherein adjacent
ends of adjacent prostheses are interleaved to resist rotation of
the prostheses relative to each other.
15. The prosthesis delivery catheter of claim 14, wherein a distal
end of the pushing element is interleaved with a proximal end of a
proximal-most prosthesis to resist rotation of the prostheses.
16. The prosthesis delivery catheter of claim 1, wherein the coil
member is configured to maintain rotational position of the
prostheses relative to each other.
17. A prosthesis delivery catheter for delivering prostheses into a
vessel lumen comprising: an outer shaft forming a first lumen; an
inner shaft slidably disposed within the first lumen; an evertible
tube having a first end coupled with a distal end of the outer
shaft and a second end coupled with a distal end of the inner
shaft; and a plurality of self-expanding tubular prostheses carried
within the evertible tube, the prostheses being adapted to radially
expand upon deployment from the evertible tube, wherein moving the
outer shaft proximally relative to the inner shaft everts a distal
portion of the evertible tube so as to deploy one or more of the
prostheses.
18. The prosthesis delivery catheter of claim 17, wherein an inner
surface of the inner shaft comprises at least one adherent element
for releasably holding the prostheses to the inner surface.
19. The prosthesis delivery catheter of claim 18, wherein the
adherent element comprises a tacky surface coating.
20. The prosthesis delivery catheter of claim 18, wherein the
adherent element comprises a softenable material into which the
prostheses are removably embedded.
21. The prosthesis delivery catheter of claim 18, wherein the
adherent element comprises a plurality of inwardly-facing
protrusions positioned to extend through openings in the
prostheses.
22. The prosthesis delivery catheter of claim 21, wherein the
protrusions have a shape selected from the group consisting of
mushroom-shaped, L-shaped, T-shaped, hook-shaped, rounded, spiked,
pyramidal, barbed, arrow-shaped and linear.
23. The prosthesis delivery catheter of claim 18, wherein the
adherent element comprises a structure selected from the group
consisting of bumps, bristles, spines, ridges ribs, waves, grooves,
pits, channels, detents and random surface irregularities.
24. A method of delivering one or more prostheses to a treatment
site in a vessel comprising: positioning a delivery catheter at the
treatment site, the delivery catheter carrying a plurality of
self-expanding prostheses; selecting a desired number of the
prostheses to deploy; deploying the desired number of prostheses
from the delivery catheter into the vessel, each prosthesis
expanding into contact with the vessel upon deployment; controlling
axial displacement of each of the selected number of prostheses
relative to the delivery catheter during deployment of the
prostheses with an expandable coil member coupled with the
prostheses; and removing the expandable coil member from the
deployed prostheses.
25. A method as in claim 24, wherein removing the coil member
comprises rotating the coil member.
26. A method as in claim 25, wherein the coil member is helically
threaded through the prostheses, and rotating the coil member
unthreads the coil member from one or more prostheses.
27. A method as in claim 24, further comprising controlling
rotational displacement of the selected number of prostheses
relative to the delivery catheter during deployment of the
prostheses.
28. A method as in claim 27, wherein the rotational displacement is
controlled by interleaving adjacent ends of adjacent prostheses and
interleaving a proximal end of a proximal-most prosthesis with a
portion of the catheter device.
29. A method as in claim 24, wherein a distal portion of the coil
member expands with the selected number of prostheses.
30. A method of delivering one or more prostheses to a treatment
site in a vessel comprising: positioning a delivery catheter at the
treatment site, the delivery catheter carrying a plurality of
self-expanding prostheses within an evertible tube; selecting a
desired number of the prostheses to deploy; and everting a distal
portion of the evertible tube to deploy the desired number of
prostheses from the delivery catheter into the vessel, each
prosthesis expanding into contact with the vessel upon
deployment.
31. A method as in claim 30, wherein the distal portion of the
evertible tube is everted by sliding an outer shaft of the catheter
device relative to an inner shaft of the catheter device.
32. A method as in claim 31, wherein a distal end of the outer
shaft is coupled with a distal end of the evertible tube, and
wherein sliding the outer shaft proximally relative to the inner
shaft causes the distal end of the evertible tube to bend outward
and fold over on itself.
33. A method as in claim 30, further comprising controlling axial
displacement of each of the selected number of prostheses relative
to the delivery catheter during deployment of the prostheses by
contacting an adherent inner surface of the evertible tube with the
prostheses.
34. A method as in claim 33, wherein the adherent surface maintains
engagement with the prostheses until the distal portion of the
evertible tube is peeled away from the prostheses.
35. A method as in claim 33, wherein the adherent surface comprises
a friction-inducing coating or friction-inducing surface
feature.
36. A method as in claim 33, wherein contacting the adherent
surface with the prostheses comprises releasably coupling one or
more retention structures on the inner surface with the
prostheses.
37. A method as in claim 33, wherein contacting the adherent
surface with the prostheses comprises embedding the prostheses in a
deformable material on the adherent inner surface.
38. A prosthesis delivery catheter comprising: an outer shaft
having a distal end and a first lumen; a plurality of
self-expanding tubular prostheses carried within the first lumen,
the prostheses being adapted to radially expand upon deployment
from the first lumen; and a control member extending distally from
the distal end of the outer shaft and defining an interior
communicating with the first lumen for receiving one or more of the
prostheses, the control member having an undeflected shape when not
engaged by any of the prostheses and being configured to deflect
radially outwardly when engaged by a prosthesis during the
expansion thereof, the control member being configured to
resiliently return to the undeflected shape when the prosthesis is
removed from the interior.
39. The prosthesis delivery catheter of claim 38, wherein the
control member comprises a plurality of tines arranged in a
generally cylindrical pattern, the tines being outwardly
deflectable as the prostheses expand.
40. The prosthesis delivery catheter of claim 39, wherein the
control member further comprises a web extending between the
tines.
41. The prosthesis delivery catheter of claim 40, wherein the web
is a distensible elastomer.
42. The prosthesis delivery catheter of claim 38, wherein the
control member comprises a radially distensible elastomeric
tube.
43. The prosthesis delivery catheter of claim 38, further
comprising: an inner shaft slidable relative to the outer shaft;
and a nose piece at the distal end of the inner shaft disposed
distally of the control member, the nose piece having a proximal
opening adapted to receive a distal end of the control member.
44. The prosthesis delivery catheter of claim 43, wherein the
control member comprises a plurality of tines arranged in a
generally cylindrical pattern, the tines having inwardly-oriented
distal tips for positioning in the proximal opening of the nose
piece.
45. The prosthesis delivery catheter of claim 38, wherein the
control member is adapted to be slidably removed from the
prosthesis following the expansion thereof.
46. The prosthesis delivery catheter of claim 38, wherein the
prostheses are adapted for deployment in groups of at least two at
a single treatment site.
47. The prosthesis delivery catheter of claim 46, wherein each of
the prostheses has axially extending elements configured to
interleave with axially extending elements on an adjacent
prosthesis.
48. The prosthesis delivery catheter of claim 47, wherein the
control member is adapted to control expansion of the prostheses
such that the axially extending elements remain interleaved when at
least two prostheses are deployed adjacent to each other.
49. The prosthesis delivery catheter of claim 38, further
comprising a pusher slidably disposed within the first lumen, the
pusher engaging at least one of the prostheses to deploy the
prostheses from the first lumen.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation-in-part of U.S.
patent application Ser. No. 10/879,949 (Attorney Docket No.
021629-002700US), filed Jun. 28, 2004, the full disclosure of which
is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] Stents are tubular prostheses designed for implantation in a
vessel to maintain patency of the vessel lumen. Stents are used in
various vessels throughout the body, including the coronary
arteries, femoral arteries, iliac arteries, renal artery, carotid
artery, vascular grafts, biliary ducts, trachea, and urethra, to
name some examples. Stents are typically implanted by means of long
and flexible delivery catheters that carry the stents in a compact,
collapsed shape to the treatment site and then deploy the stents
into the vessel. In some applications, balloon expandable stents
are used. These stents are made of a malleable metal such as
stainless steel or cobalt chromium and are expanded by means of a
balloon on the tip of the delivery catheter to plastically deform
the stent into contact with the vessel wall. In other applications,
self-expanding stents are used. These are made of a resilient
material that can be collapsed into a compact shape for delivery
via catheter and that will self-expand into contact with the vessel
when deployed from the catheter. Materials commonly used for
self-expanding stents include stainless steel and elastic or
superelastic alloys such as nickel titanium (Nitinol.TM.).
[0003] While self-expanding stents have demonstrated promise in
various applications, such stents face a number of challenges. One
such challenge is that in some cases the disease in a vessel may be
so extensive that a stent of very long length, e.g. 30-200 mm, is
called for. Currently available stents are typically less than 30
mm in length, and suffer from excessive stiffness if made longer.
Such stiffness is particularly problematic in peripheral vessels
such as the femoral arteries, where limb movement requires a high
degree of flexibility in any stent implanted in such vessels.
[0004] To overcome the stiffness problem, the idea of deploying
multiple shorter stents end-to-end has been proposed. However, this
approach has suffered from several drawbacks. First, currently
available delivery catheters are capable of delivering only a
single stent per catheter. In order to place multiple stents,
multiple catheters must be inserted, removed and exchanged,
heightening risks, lengthening procedure time, raising costs, and
causing excessive material waste. In addition, the deployment of
multiple stents end-to-end suffers from the inability to accurately
control stent placement and the spacing between stents. This
results in overlap of adjacent stents and/or excessive space
between stents, which is thought to lead to complications such as
restenosis, the renarrowing of a vessel following stent placement.
With self-expanding stents the problem is particularly acute
because as the stent is released from the catheter, its resiliency
tends to cause it to eject or "watermelon seed" distally from the
catheter tip by an unpredictable distance. During such deployment,
the stent may displace not only axially but rotationally relative
to the delivery catheter resulting in inaccurate, uncontrollable,
and unpredictable stent placement.
[0005] Interleaving stents or stent segments such as those
disclosed in co-pending application Ser. No. 10/738,666, filed Dec.
16, 2003, which is incorporated herein by reference, present even
greater challenges to conventional delivery systems. Interleaving
stents have axially extending elements on each end of the stent
that interleave with similar structures on an adjacent stent. Such
interleaving minimizes the gap between adjacent stents and
increases vessel wall coverage to ensure adequate scaffolding and
minimize protrusion of plaque from the vessel wall. However, such
interleaving requires that the relative rotational as well as axial
positions of the adjacent stents be maintained during deployment to
avoid metal overlap and excessive gaps between stents. Conventional
delivery systems suffer from the inability to control both the
axial and rotational positions of self-expanding stents as they are
deployed.
[0006] What are needed, therefore, are stents and stent delivery
system that overcome the foregoing problems. In particular, the
stents and stent delivery systems should facilitate stenting of
long vascular regions of various lengths without requiring the use
of multiple catheters. Such stents and delivery systems should also
provide sufficient flexibility for use in peripheral vessels and
other regions where long and highly flexible stents might be
required. In addition, the stents and stent delivery systems should
enable the delivery of multiple stents of various lengths to one or
more treatment sites using a single catheter without requiring
catheter exchanges. Further, the stents and stent delivery systems
should facilitate accurate and repeatable control of stent
placement and inter-stent spacing to enable deployment of multiple
self-expanding stents end-to-end in a vessel at generally constant
spacing and without overlap. Moreover, the stents and delivery
systems should enable the deployment of interleaving stents or
stent segments with precision and control over both the axial
spacing and rotational position of each stent or segment.
BRIEF SUMMARY OF THE INVENTION
[0007] The present invention provides prostheses, prosthesis
delivery systems, and methods of prosthesis deployment that enable
the precise and controllable delivery of multiple prostheses using
a single delivery catheter. The prostheses, delivery systems, and
methods of the invention provide for the precise control of
prosthesis placement so that inter-prosthesis spacing is maintained
at a constant and optimum distance. In some embodiments, both axial
and rotational displacement of the prostheses relative to the
delivery catheter is controlled during deployment, enabling the
delivery of multiple prostheses that interleave with one another
without overlap. The prostheses, prosthesis delivery systems, and
methods of the invention further enable the length of prostheses to
be customized in situ to match the length of the site to be
treated. The invention is particularly useful for delivery of
self-expanding prostheses, but balloon expandable prostheses are
also contemplated within the scope of the invention. The invention
is well-suited to delivery of stents to the coronary arteries and
to peripheral vessels such as the popliteal, femoral, tibial,
iliac, renal, and carotid arteries. The invention is further useful
for delivery of prostheses to other vessels including biliary,
neurologic, urinary, reproductive, intestinal, pulmonary, and
others, as well as for delivery of other types of prostheses to
various anatomical regions, wherever precise control of prosthesis
deployment is desirable.
[0008] In a first aspect of the present invention, a prosthesis
delivery catheter includes an outer shaft forming a first lumen, a
plurality of self-expanding tubular prostheses carried within the
first lumen, and a movable coil member interactive with the
prostheses to control expansion of the prostheses when the
prostheses are deployed from the first lumen. The prostheses are
generally adapted to radially expand upon deployment from the first
lumen.
[0009] In some embodiments, the coil member is removable from the
deployed prostheses by rotating the coil member. In some
embodiments, the prostheses have sidewalls with a plurality of
openings, the coil member being threaded through the openings.
Alternatively, the prostheses may include a plurality of struts, at
least one of the struts being bent inwardly, with the coil member
being threaded through the inwardly bent struts. Optionally, the
coil member may be radially expandable to allow controlled
expansion of the prostheses. In some embodiments, a distal portion
of the coil member is retractable into the outer shaft following
deployment of the selected number of prostheses. In some
embodiments, the prostheses are disposed within the coil
member.
[0010] In various embodiments, the coil member may include a
plurality of loops forming a helix. For example, in some
embodiments between 2 and 6 loops are disposed in each prosthesis.
In other embodiments, more than 6 loops are disposed in each
prosthesis. In some embodiments, the coil member comprises a
plurality of loops contacting each other to form a continuous
tube.
[0011] Optionally, the delivery catheter may also include a
deployment mechanism for deploying a selected number of prostheses
from the inner lumen. In some embodiments, for example, the
deployment mechanism includes a pushing element slidably disposed
in the first lumen, the pushing element being in engagement with at
least one of the prostheses to advance the prostheses distally
relative to the outer shaft. Optionally, adjacent ends of adjacent
prostheses may be interleaved to resist rotation of the prostheses
relative to each other. In one embodiment, a distal end of the
pushing element is interleaved with a proximal end of a
proximal-most prosthesis to resist rotation of the prostheses. In
these or other embodiments, the coil member may optionally be
configured to maintain rotational position of the prostheses
relative to each other.
[0012] In another aspect of the present invention, a prosthesis
delivery catheter for delivering prostheses into a vessel lumen
includes an outer shaft forming a first lumen, an inner shaft
slidably disposed within the first lumen, an evertible tube having
a first end coupled with a distal end of the outer shaft and a
second end coupled with a distal end of the inner shaft, and a
plurality of self-expanding tubular prostheses carried within the
evertible tube. Again, the prostheses are generally adapted to
radially expand upon deployment from the evertible tube. Moving the
outer shaft proximally relative to the inner shaft everts a distal
portion of the evertible tube so as to deploy one or more of the
prostheses.
[0013] In some embodiments, an inner surface of the inner shaft
comprises at least one adherent element for releasably holding the
prostheses to the inner surface. For example, in one embodiment,
the adherent element comprises a tacky surface coating.
Alternatively, the adherent element may comprise a softenable
material into which the prostheses are removably embedded. In other
embodiments, the adherent element comprises a plurality of
inwardly-facing protrusions positioned to extend through openings
in the prostheses. Such protrusions may have any of a number of
shapes in various embodiments, such as but not limited to
mushroom-shaped, L-shaped, T-shaped, hook-shaped, rounded, spiked,
pyramidal, barbed, arrow-shaped or linear. In yet other
embodiments, the adherent element may comprise a structure such as
but not limited to bumps, bristles, spines, ridges ribs, waves,
grooves, pits, channels, detents or random surface
irregularities.
[0014] In another aspect of the present invention, a method of
delivering one or more prostheses to a treatment site in a vessel
involves: positioning a delivery catheter at the treatment site,
the delivery catheter carrying a plurality of self-expanding
prostheses; selecting a desired number of the prostheses to deploy;
deploying the desired number of prostheses from the delivery
catheter into the vessel, each prosthesis expanding into contact
with the vessel upon deployment; controlling axial displacement of
each of the selected number of prostheses relative to the delivery
catheter during deployment of the prostheses with an expandable
coil member coupled with the prostheses; and removing the
expandable coil member from the deployed prostheses.
[0015] In some embodiments, removing the coil member involves
rotating the coil member. For example, the coil member may be
helically threaded through the prostheses such that rotating the
coil member unthreads the coil member from one or more prostheses.
In some embodiments, the method also involves controlling the
rotational displacement of the selected number of prostheses
relative to the delivery catheter during deployment of the
prostheses. In one embodiment, for example, the rotational
displacement is controlled by interleaving adjacent ends of
adjacent prostheses and interleaving a proximal end of a
proximal-most prosthesis with a portion of the catheter device. In
some embodiments, a distal portion of the coil member expands with
the selected number of prostheses.
[0016] In yet another aspect of the present invention, a method of
delivering one or more prostheses to a treatment site in a vessel
involves: positioning a delivery catheter at the treatment site,
the delivery catheter carrying a plurality of self-expanding
prostheses within an evertible tube; selecting a desired number of
the prostheses to deploy; and everting a distal portion of the
evertible tube to deploy the desired number of prostheses from the
delivery catheter into the vessel, each prosthesis expanding into
contact with the vessel upon deployment. In some embodiments, the
distal portion of the evertible tube is everted by sliding an outer
shaft of the catheter device relative to an inner shaft of the
catheter device. For example, in some embodiments, a distal end of
the outer shaft is coupled with a distal end of the evertible tube
such that sliding the outer shaft proximally relative to the inner
shaft causes the distal end of the evertible tube to bend outward
and fold over on itself.
[0017] Optionally, the method may further involve controlling axial
displacement of each of the selected number of prostheses relative
to the delivery catheter during deployment of the prostheses by
contacting an adherent inner surface of the evertible tube with the
prostheses. In one embodiment, for example, the adherent surface
maintains engagement with the prostheses until the distal portion
of the evertible tube is peeled away from the prostheses. In some
embodiments, the adherent surface comprises a friction-inducing
coating or friction-inducing surface feature. In some embodiments,
contacting the adherent surface with the prostheses involves
releasably coupling one or more retention structures on the inner
surface with the prostheses. Alternatively, contacting the adherent
surface with the prostheses may involve embedding the prostheses in
a deformable material on the adherent inner surface.
[0018] In a further aspect of the invention, a prosthesis delivery
catheter comprises an outer shaft having a distal end and a first
lumen, a plurality of self-expanding tubular prostheses carried
within the first lumen, the prostheses being adapted to radially
expand upon deployment from the first lumen, and a control member
extending distally from the distal end of the outer shaft and
defining an interior communicating with the first lumen for
receiving one or more of the prostheses. The control member has an
undeflected shape when not engaged by one of the prostheses and is
configured to deflect radially outwardly when engaged by a
prosthesis during expansion thereof. The control member is also
configured to resiliently return to the undeflected shape when the
prosthesis is removed from the interior. In one embodiment, the
control member generally includes a plurality of deflectable tines
having free distal ends received within an aperture on the nose
cone or nose piece of the catheter. Optionally, the control member
may further include a plurality of webs between the tines. In an
alternative embodiment, the control member may comprise a
distensible tubular structure.
[0019] Further aspects of the nature and advantages of the
invention will be apparent from the following detailed description
of various embodiments of the invention taken in conjunction with
the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] FIG. 1 is a side cut-away view of a prosthesis delivery
catheter according to the invention.
[0021] FIG. 2A is a side cross-sectional view of a distal portion
of a prosthesis delivery catheter according to the invention in a
further embodiment thereof.
[0022] FIG. 2B is a side cross-sectional view of the prosthesis
delivery catheter of FIG. 2A showing the deployment of prostheses
in a vessel.
[0023] FIGS. 3A-3C are perspective, side, and end views
respectively of a prosthesis coupled to control wires according to
further embodiments of the invention.
[0024] FIG. 4A is a side cross-section of a distal portion of a
prosthesis delivery catheter according to the invention in a
further embodiment thereof.
[0025] FIG. 4B is a side cross-section of the prosthesis delivery
catheter of FIG. 4A showing the deployment of prostheses in a
vessel.
[0026] FIG. 5 A is a side cross-section of a distal portion of a
prosthesis delivery catheter according to the invention in a
further embodiment thereof.
[0027] FIG. 5B is an oblique view of a distal portion of a
prosthesis delivery catheter according to the invention in yet
another embodiment thereof.
[0028] FIGS. 6A-6C are side cross-sectional views of a distal
portion of a prosthesis delivery catheter according to the
invention in still another embodiment thereof, showing the outer
shaft unretracted, outer shaft retracted with sleeve unexpanded,
and sleeve with stents expanded, respectively.
[0029] FIGS. 7A-7B are side cross-sectional views of a distal
portion of a prosthesis delivery catheter according to the
invention in another embodiment thereof, showing outer shaft
retracted with sleeve unexpanded, and outer shaft retracted with
sleeve and stents expanded, respectively.
[0030] FIGS. 8A-8C are side cross-sectional views of a distal
portion of a prosthesis delivery catheter according to the
invention in a further embodiment thereof, showing the outer shaft
unretracted, outer shaft retracted with sleeve unexpanded, and
sleeve with stents expanded, respectively.
[0031] FIGS. 9A-9B are side cross-sectional views of a distal
portion of a prosthesis delivery catheter in a vessel according to
the invention in another embodiment thereof, showing outer shaft
retracted with prosthesis partially deployed, and prosthesis fully
deployed, respectively.
[0032] FIGS. 10A-10B are side cross-sectional views of a distal
portion of a prosthesis delivery catheter in a vessel according to
the invention in yet another embodiment thereof, showing outer
shaft retracted with prosthesis partially deployed, and prosthesis
fully deployed, respectively.
[0033] FIGS. 11A-11C are side cross-sectional views of a distal
portion of a prosthesis delivery catheter in a vessel according to
the invention in yet another embodiment thereof, showing a first
prosthesis deployed, an expandable member expanded within the first
prosthesis, and a second stent deployed with expandable member
expanded in the first prosthesis, respectively.
[0034] FIGS. 11D-11F are side cross-sectional views of a distal
portion of a prosthesis delivery catheter according to another
embodiment of the invention, showing the delivery catheter prior to
stent deployment, the deployment of a first prosthesis in a vessel,
and a deployed prosthesis in the vessel, respectively.
[0035] FIG. 12 is a side cross-sectional view of a distal portion
of a prosthesis delivery catheter in a vessel according to the
invention in still another embodiment thereof, showing a first
prosthesis deployed in a lesion.
[0036] FIGS. 13A-13C are side cross-sectional views of a distal
portion of a prosthesis delivery catheter according to another
embodiment of the invention, demonstrating a method for delivering
prostheses in a vessel.
[0037] FIG. 14 is a side view of a prosthesis coupled with a coil
member according to one embodiment of the invention.
[0038] FIG. 15 is an end-on view of a prosthesis coupled with a
coil member according to one embodiment of the invention.
[0039] FIG. 16 is an end-on view of a prosthesis coupled with a
coil member according to another embodiment of the invention.
[0040] FIG. 17 is a cross-sectional side view of a distal end of a
prosthesis delivery catheter having an evertible tube according to
one embodiment of the present invention.
[0041] FIG. 18 is a cross-sectional side view of a portion of an
evertible tube of a prosthesis delivery catheter according to one
embodiment of the present invention.
[0042] FIG. 19 is a cross-sectional side view of a portion of an
evertible tube of a prosthesis delivery catheter according to
another embodiment of the present invention.
[0043] FIGS. 20A-20B are oblique views a prosthesis delivery
catheter according to the invention in a further embodiment
thereof, before and during deployment of a prosthesis,
respectively.
[0044] FIGS. 21A-21E are side cross-sectional views of the
prosthesis delivery catheter of FIGS. 20A-B, illustrating the steps
of deploying a prosthesis according to the invention.
[0045] FIG. 22 is an oblique view of a distal end of a prosthesis
delivery catheter according to the invention in a further
embodiment thereof.
[0046] FIG. 23 is an oblique view of a distal end of a prosthesis
delivery catheter according to the invention in still another
embodiment thereof.
DETAILED DESCRIPTION OF THE INVENTION
[0047] Referring to FIG. 1, a first embodiment of a prosthesis
delivery catheter according to the invention is illustrated.
Delivery catheter 20 may have any of various constructions,
including that described in co-pending application Ser. No.
10/637,713, filed Aug. 8, 2003 (Attorney Docket No. 21629-000340),
which is incorporated herein by reference. Delivery catheter 20 has
a handle assembly 21 and an elongated catheter body 22 that
includes three concentric tubular shafts all axially slidable
relative to one another: an outer shaft 24, a pusher 26, and an
inner shaft 28. Pusher 26 has a distal extension 27 to which a
pusher ring 29 is fixed. In a distal region of the catheter body
22, a guidewire tube 30 extends slidably through a port 32 in outer
shaft 24 and through pusher ring 29 and has a distal end 34, to
which is mounted a nosecone 36 and a stop member 38.
[0048] Delivery catheter 20 further includes one or more stent
expansion control members, which in the illustrated embodiment
comprise a plurality of control wires 40. Preferably, one or more
pairs of control wires 40 are mounted on opposing sides of delivery
catheter 20, e.g. four control wires 40 offset 90.degree. from each
other. Control wires 40 are fixed at their proximal ends 42 to
inner shaft 28, and have free distal ends 44.
[0049] Outer shaft 24 has a distal extremity 46 defining a first
lumen 48. A plurality of stents 50 are disposed in a collapsed
configuration within first lumen 48. Stents 50 are preferably
composed of a resilient material such as stainless steel or Nitinol
so as to self-expand from the collapsed configuration to a radially
expanded configuration when deployed from first lumen 48. While
stents 50 as illustrated have a wave-like or undulating pattern in
a plurality of interconnected circumferential members, the pattern
illustrated is merely exemplary and the stents of the invention may
have any of a variety of strut shapes, patterns, and geometries.
From 2 up to 10 or more stents may be carried by outer shaft 24.
Optionally, a valve member 49 is mounted within first lumen 48 to
facilitate separating those stents 50 to be deployed from those to
remain within outer shaft 24, as described in co-pending
application Ser. No. 10/412,714, filed Apr. 10, 2003, which is
incorporated herein by reference.
[0050] Control wires 40 run along the outside of stents 50 or
through the interior of stents 50, are threaded through openings in
the walls of stents 50 or are otherwise coupled with stents 50 to
control the deployment thereof, as described more fully below.
Control wires 40 are composed of a resilient material such as
stainless steel, Nitinol, or a suitable polymer, and are preferably
generally straight and biased inwardly against guidewire tube 32 or
to a position generally parallel to the axial direction. In FIG. 1,
outer shaft 24 has been retracted to expose a plurality of stents
50 which are partially expanded and remain coupled to or restrained
by control wires 40, as explained in greater detail below.
[0051] Handle assembly 21 has a rotatable retraction knob 52
coupled to a shaft housing 53, to which outer shaft 24 is fixed. By
rotating retraction knob 52, outer shaft 24 may be retracted
proximally relative to pusher 26 and inner shaft 28. A pull ring 54
is coupled to inner shaft 28, allowing inner shaft 28, and hence
control wires 40, to be retracted proximally relative to outer
shaft 24. A switch 56 engages and disengages pusher 26 with outer
shaft 28, so that pusher 26 either moves with outer shaft 24 or
remains stationary as outer shaft 24 is retracted. Indicia 58 on
shaft housing 53 indicate the extent of retraction of outer shaft
28 by distance, number of stents, or other suitable measure. Other
aspects of handle assembly 21 are described in co-pending
application Ser. No. 10/746,466, filed Dec. 23, 2003 (Attorney
Docket No. 21629-002200), which is incorporated herein by
reference. Except as stated otherwise, any of the embodiments of
the stent delivery catheter described below may incorporate the
features and be otherwise constructed as just described.
[0052] FIGS. 2A-2B illustrate a distal extremity of a stent
delivery catheter 60 according to the invention in a further
embodiment thereof. In this embodiment, stents 62 have a series of
diamond shaped openings 64 in the walls thereof through which a
plurality of control wires 66 are threaded. Stents 62 have a
plurality of axially-extending V-shaped points 63 on their distal
and proximal ends. These points 63 are configured to interleave or
nest with the points 63 on the adjacent stent 62, preferably both
in the collapsed and expanded configurations. Various suitable
interleaving stent geometries are described in co-pending
application Ser. No. 10/736,666, filed Dec. 16, 2003, which is
incorporated herein by reference. In order to maintain this
interleaving, it is important to maintain the relative rotational
and axial positions of the adjacent stents 62 both before and
during deployment. By extending through the openings 64 in each
stent, control wires 66 keep adjacent stents 62 in rotational
alignment as they are advanced forward through the catheter and
during deployment. Preferably, each control wire 66 is threaded
through at least two openings 64 in each stent 62, one opening 64a
near the distal end of each stent 62 and one opening 64b near the
proximal end of each stent 62. Alternatively, control wires 66 may
be threaded through only a single opening 64 or through three or
more openings 64 on each stent 62. Preferably, however, control
wires 66 are threaded so that the distal and proximal ends of
stents 64 will expand at a generally uniform rate when released, as
described below.
[0053] Control wires 66 are constructed of a resilient and flexible
metal or polymer with sufficient stiffness to provide controlled
resistance to the expansion of stents 62. This stiffness may be
selected to allow the desired expansion behavior of stents 62 such
that "watermelon seeding" is avoided, inter-stent spacing is
maintained, and sufficient stent expansion occurs. Control wires 66
may have various cross-sectional geometries, and may be a flat
ribbons or blades, round or oval wires, I-beams, or other suitable
structures to control stent expansion, maintain spacing and
rotational position, and facilitate withdrawal from stents 62
without interference. Control wires 66 may be composed of or coated
with a lubricious material such as PTFE to reduce friction during
removal from stents 62. In other embodiments, control wires 66 may
have surface features, be wrapped with wire windings, or be coated
with "sticky" material to increase friction with stents 62.
Coatings or surface structures such as scales with one-way
frictional effects may also be applied to control wires 66.
[0054] As a further alternative, control wires 66 may comprise
flexible hollow tubes which are pneumatically or hydraulically
controllable to vary their rigidity or stiffness. For example,
control wires 66 may comprise polymeric tubes that radially
contract or flatten and are very flexible when evacuated of fluid,
but which become more rigid when filled with pressurized fluid,
such as saline, air, or other liquid or gas. In such an embodiment,
control wires 66 are fluidly connected to a pump, syringe, or other
suitable fluid delivery mechanism at the proximal end of the
delivery catheter. In this way, control wires 66 may be pressurized
to increase stiffness as stents 62 are deployed, then evacuated of
fluid to reduce their profile and stiffness during withdrawal from
the deployed stents.
[0055] Stents 62 are slidably positioned over an inner shaft 68, to
which is attached a nosecone 70 at the distal end of the device. An
outer shaft 72 is slidably disposed over inner shaft 68 and
surrounds stents 62, maintaining them in a collapsed configuration,
as shown in FIG. 2A. A pusher shaft 74 is slidably disposed over
inner shaft 68 and is configured to engage the proximal end of the
proximal-most stent 62. Outer shaft 72 is retractable relative to
inner shaft 68 in order to expose a desired number of stents 62 as
shown in FIG. 2B. When outer shaft 72 is retracted, the exposed
stents 62 self-expand to a larger-diameter expanded shape in
engagement with lesion L in vessel V. Preferably, at least the
distal end of the distal-most stent 62, and more preferably a
substantial portion of all stents 62 being deployed, is allowed to
expand into engagement with lesion L while control wires 66 remain
threaded through openings 64. Control wires 66 are then withdrawn
from openings 62, preferably by holding catheter 60 in position and
pulling control wires 66 proximally using a suitable mechanism such
as that described above with reference to FIG. 1. Alternatively,
the entire catheter 60 may be retracted proximally relative to
stents 62 to withdraw control wires 66 from openings 62. Because at
least a portion of stents 62 is in engagement with lesion L, stents
62 are held in position in the vessel as control wires 66 are
withdrawn.
[0056] Optionally, inner shaft 68 may have a balloon 76 mounted
thereto near its distal end to enable pre- or post-dilatation of
lesion L. In this embodiment, inner shaft 68 has an inflation lumen
through which inflation fluid may be delivered to balloon 76.
Balloon 76 is preferably as long as the longest lesion that might
be treated using catheter 60. To dilate lesion L prior to stent
deployment, or to further expand stents 62 after deployment, outer
shaft 72 and those of stents 62 remaining therein are retracted
relative to inner shaft 68 to expose a desired length of balloon
76. The exposed portion of balloon 76 may then be inflated within
the lesion L and/or the deployed stents 62.
[0057] Following deployment and any post-dilatation, inner shaft 68
is retracted into outer shaft 72 while maintaining pressure against
pusher shaft 74. This slides stents 62 distally along control wires
66 and repositions stents 62 to the distal end of inner shaft 68 so
as to be ready for deployment. Catheter 60 may then be repositioned
to another vascular location for deployment of additional stents
62.
[0058] Control wires 66 may be coupled to stents 62 in various
ways, some of which depend upon the configuration of stents 62. For
example, as shown in FIGS. 3A-B, the points 63 at the ends of each
stent 62 may be bent inwardly such that a portion of the openings
64' are oriented axially. Control wires 66 may then be threaded
through these axially-oriented openings 64'. Preferably, upon
deployment, points 63 are adapted to deform with stent expansion so
as to be more parallel to the axial direction, thereby providing a
smooth and open flow path through the stent.
[0059] In another embodiment, shown in FIG. 3C, stents 80 have
axially-aligned eyelets 82 through which control wires 84 are
threaded. These eyelets 82 may be in the interior of stents 82 as
shown in FIG. 3C, or such eyelets may be on the exterior surface of
stents 82, or could be drilled through one or more of the struts of
stents 82. Various other structures may also be used for coupling
the stents of the invention to control wires, including hooks,
channels, holes, sleeves, and others, disposed on the interior,
exterior or end surfaces of the stent, or through the struts
themselves. Such structures may by integral with stent struts and
of the same material, may be attached to the stent struts and be of
same or different material, or may be a biodegradable material that
erodes and eventually is absorbed into the body following
deployment.
[0060] Referring now to FIGS. 4A-4B, in a further embodiment, a
stent delivery catheter 90 has an outer shaft 92 slidably disposed
over an inner shaft 94, and at least one stent 96 (shown
schematically in FIG. 4A) in a collapsed shape within outer shaft
92. A plurality of control wires 97 have an outer extremity 98
outside of inner shaft 94 and an inner extremity 100 extending
through one or more lumens 102 and distal ports 103 in inner shaft
94. Both outer portion 98 and inner portion 100 extend proximally
to the proximal end of delivery catheter 90. Outer extremities 98
are threaded through openings in the wall of stent 96 or are
otherwise coupled thereto as described above so as to resist
expansion of stent 96 upon deployment. Control wires 97 thus form a
continuous loop from the proximal end of stent delivery catheter
90, through stent 96 and back to the proximal end of the
catheter.
[0061] FIG. 4B illustrates this embodiment of delivery catheter 90
positioned in a vessel V and carrying plurality of stents 96'.
Stents 96' have axial projections 104 at their distal and proximal
ends configured to interleave when stents 96' are collapsed within
outer shaft 92 and when deployed in vessel V. When outer shaft 92
is retracted to expose one or more stents 96', the expansion of
stents 96' can be resisted and controlled by maintaining tension on
control wires 97. Tension may be controllably relaxed to allow
stents 96' to expand into contact with lesion L, as shown in FIG.
4B. By controlling the expansion in this way, the axial spacing and
rotational positions of adjacent stents 96' may be maintained so
that gaps and overlaps are minimized and the interleaving of axial
projections 104 is maintained. When stents 96' are fully expanded,
one end of each control wire 97 may be released at the proximal end
of delivery catheter 90 while the other end is pulled to retract
the control wires from stents 96'.
[0062] In a further embodiment, illustrated schematically in FIGS.
5A-B, delivery catheter 108 is constructed as described above
except that control wires 110 are releasably coupled to the distal
end of an inner shaft 112 or to nose cone 114. In an exemplary
embodiment, control wires 110 have balls 116 at their distal ends
configured to be received within slots 118 on the outer surface of
nosecone 114 (FIG. 5A) or on the proximal face of nosecone 114
(FIG. 5B; outer shaft not shown for clarity). Slots 118 have an
enlarged portion 120 of sufficient size to receive ball 116 and a
narrow portion 122 through which balls 116 may not pass. Inner
shaft 112 is axially rotatable relative to control wires 110. As in
the embodiment of FIGS. 4A-B, with balls 116 held within slots 118,
tension may be maintained on control wires 110 to resist expansion
of stent 124. Stent 124 may be allowed to expand by gradually
relaxing tension on control wires 110. Once stent 124 is fully
expanded tension on control wires 110 may be fully relaxed and
nosecone 114 then rotated by rotating inner shaft 112, thereby
allowing balls 116 to pass through enlarged portions 120. Control
wires 110 may then be withdrawn from the deployed stent 124.
Nosecone 114 is then retracted or control wires 110 advanced so as
to reinsert balls 116 into slots 118. Nosecone 114 is then rotated
to align balls 116 with narrow portions 122, again securing the
control wires to nosecone 114. Delivery catheter 108 may then be
repositioned to deploy additional stents.
[0063] Optionally, delivery catheter 108 may include a middle shaft
or balloon 126 over which stents 124 are positioned, as shown in
FIG. 5A. In this case, inner shaft 112 is slidably and rotatably
disposed in an inner lumen though middle shaft or balloon 126. If a
balloon is included, it may be used for pre-dilatation of lesions
prior to stent deployment, or for further expansion of stent 124
following deployment.
[0064] In the foregoing embodiment, control wires 110 will be
constructed to have sufficient stiffness to resist rotation,
twisting or bending as nosecone 114 is rotated to release control
wires 110. Maintaining some tension on control wires 110 as
nosecone 114 is rotated may facilitate the release process. In
addition, control wires 110 will have sufficient column strength to
facilitate reinsertion into slots 118 following deployment of
stents 124. Thus the size, material and geometry of control wires
110 will be selected to enable these actions while providing the
desired level of control of stent expansion.
[0065] In a further embodiment of a stent delivery catheter
according to the invention, an expandable sleeve 130 is slidably
positioned within outer shaft 132 and carries stents 134 as shown
in FIGS. 6A-C. A pusher shaft 136 is slidable within sleeve 130 and
engages the proximal-most stent 134. An inner shaft 138 extends
through pusher shaft 136 and has a nosecone 140 fixed to its distal
end. Sleeve 130, or at least a distal extremity thereof, may be a
tube constructed of a resilient deformable material such as
urethane or other medical grade elastomer, or may be a tubular
mesh, cage, grating, or other suitable structure of flexible and
resilient polymer or metal such as stainless steel or Nitinol. The
elasticity and stiffness of sleeve 130 are selected to allow stents
134 to expand at the desired rate when deployed from outer shaft
132 without excessive axial or rotational displacement relative to
each other or to outer shaft 132. Sleeve 130 is resiliently biased
toward an unexpanded shape so that following stent deployment,
sleeve 130 returns to a generally tubular shape. Outer shaft 132 is
constructed of a material with sufficient radial strength and
stiffness to resist expansion of stents 134 and sleeve 130, and may
include a metallic or polymeric braid, ribs, rings or other
structural reinforcement near its distal end for such purpose.
[0066] The interior surface of sleeve 130 optionally may have
surface features such as bumps, scales, bristles, ribs, or
roughness to enhance friction with stents 134. These features may
be configured to have a grain such that they provide more friction
against movement in the distal direction than in the proximal
direction, or vice versa. Further, such features may be adapted to
provide more friction when sleeve 130 is in an unexpanded shape
than when it is expanded by stents 134. For example, bristles may
be provided that point more in the proximal direction when sleeve
130 is in its unexpanded cylindrical shape, but which point more
distally or radially (perpendicular to the surface of sleeve 130)
when sleeve 130 is expanded. This allows sleeve 130 to be more
easily withdrawn from stents 134 when stents 134 are deployed.
[0067] In order to deploy stents 134, delivery catheter 129 is
positioned across a vascular lesion so that nosecone 140 is
disposed just distally of the distal end of the lesion. Outer shaft
132 is then retracted to expose the desired number of stents 134
(and the associated length of sleeve 130) which will cover the
length of the lesion, as shown in FIG. 6B. As outer shaft 132 is
retracted, stents 134 are allowed to expand into contact with the
lesion as shown in FIG. 6C. Sleeve 130 controls the rate of
expansion and maintains the positions of stents 134 so they are
deployed precisely at the intended location. Once stents 134 are
fully expanded, sleeve 130 may be retracted from between the stents
and the lesion until sleeve 130 is again disposed in outer shaft
132. Pressure is maintained on pusher shaft 136 during this process
so that the stents 134 remaining in delivery catheter 129 are
advanced to the distal end of sleeve 130 and outer shaft 132.
Delivery catheter 129 may then be repositioned for deployment of
additional stents at other locations.
[0068] Referring now to FIGS. 7A-B, in a further embodiment, a
delivery catheter 142 may be constructed largely as described in
connection with FIGS. 6A-C, including an outer shaft 144, an
expandable sleeve 146 slidably disposed therein, a pusher shaft
148, and inner shaft 150. A plurality of stents 152 are carried in
expandable sleeve 146 (shown in FIG. 7B). In order to facilitate
expansion, expandable sleeve 146 includes a longitudinal slit 154
in at least a distal extremity thereof. When outer shaft 144 is
retracted relative to sleeve 146, sleeve 146 may be controllably
expanded by axially twisting sleeve 146 such that the opposing
edges 156 along longitudinal slit 154 pivot away from one another,
forming a cone shape (FIG. 7B). In this way, the expansion of
stents 152 is further controllable after retraction of outer shaft
144 by controlling the rate of twisting of sleeve 146. An actuator
may be provided at the proximal end of delivery catheter 142 to
control such twisting. Optionally, sleeve 146 may have a helical
thread on its outer surface that mates with a complementary thread
on the interior of outer shaft 144 such that sleeve 146 is
automatically twisted as outer shaft 144 is retracted. As in the
embodiment of FIGS. 6A-C, following stent deployment, sleeve 146 is
retracted from the space between the deployed stents and the vessel
wall and returned within outer shaft 144. Sleeve 146 may be
resiliently biased to return to its unexpanded configuration, or
may be manually twisted back to an unexpanded shape by the
operator.
[0069] In another embodiment, shown in FIGS. 8A-C, delivery
catheter 160 is again constructed much like delivery catheter 129
of FIGS. 6A-C, including an outer shaft 162, a slidable expandable
sleeve 164 carrying stents 166, a pusher shaft 168, and an inner
shaft 170. A nosecone 172 is attached to the distal end of inner
shaft 170 and has a concavity 174 at its proximal end configured to
receive the distal end of sleeve 164. A distal extremity of sleeve
164 includes a plurality of axial slits 176 defining separate
deflectable longitudinal beams 178. Sleeve 164 includes at least
two, preferably four, and as many as six, eight, or more slits 176
to provide a corresponding number of longitudinal beams 178.
Longitudinal beams 178 are resiliently biased into an axial
orientation wherein sleeve 164 is generally cylindrical.
Longitudinal beams 178 have sufficient stiffness against lateral
deflection to resist and control the expansion of stents 166.
[0070] Advantageously, by containing the distal ends of
longitudinal beams 178 in concavity 174, outer shaft 162 may be
retracted to expose the desired number of stents to cover a target
lesion without immediate expansion of stents 166, as shown in FIG.
8B. When the desired number of stents 166 is exposed, inner shaft
170 may be advanced distally relative to sleeve 164, releasing
longitudinal beams 178 from concavity 174. This permits
longitudinal beams 178 to laterally deflect, allowing stents 166 to
expand, as shown in FIG. 8C. When full expansion is achieved,
longitudinal beams 178 may be retracted from between stents 166 and
the vessel wall. Longitudinal beams 178 then return to their
undeflected axial orientation, allowing inner shaft 170 to be
retracted so as to return the distal ends of longitudinal beams 178
into concavity 174. Inner shaft 170 and sleeve 164 may then be
retracted into outer shaft 162 while maintaining pressure on pusher
shaft 168, thereby advancing additional stents 166 toward the
distal end of sleeve 164 for additional deployments.
[0071] In some embodiments of the stent delivery catheter of the
invention, the stents themselves are configured to provide greater
control and precision in stent deployment. For example, FIGS. 9A-9B
illustrates a delivery catheter 180 having a plurality of stents
182 disposed in an outer shaft 184. An inner shaft 186 with
optional balloon 188 and nosecone 190 extends through outer shaft
184 and stents 182 and is axially movable relative thereto. A
pusher shaft (not shown) is slidably disposed over inner shaft 186
and engages stents 182 for purposes of deploying stents 182 from
outer shaft 186 and repositioning the remaining stents 182 within
outer shaft 186, as in earlier embodiments. In this embodiment,
stents 182 comprise a plurality of struts 191 forming a series of
rings 192 interconnected at joints 193. Each ring 192 has a series
of closed cells 194 interconnected circumferentially and having an
"I" shape in the unexpanded configuration.
[0072] As outer shaft 184 is retracted to deploy one or more stents
182, at least a distal ring 192' is configured to expand into
engagement with the vessel wall before the entire length of the
stent 182 is deployed from outer shaft 184 (FIG. 9A). Once in
engagement with the lesion L in vessel V, distal ring 192' anchors
stent 182 in position as the remainder of the stent is deployed
(FIG. 9B), preventing "watermelon seeding" of the stent from the
catheter. The axial length of stent 182, the length of each ring
192, the number of rings, the stiffness of struts 191, and the
flexibility of joints 193 are all selected to optimize this
deployment behavior. Each stent 182 has at least two, and
preferably four or more rings 192, each ring being about 2-5 mm in
length, giving stent 182 an overall length of at least about 8-20
mm. Of course, stents of shorter or longer length are also
contemplated within the scope of the invention. Lesions longer than
each stent 182 may be treated by deploying multiple stents 182
end-to-end. Advantageously, each stent 182 can be deployed
precisely at a desired spacing from a previously-deployed stent 182
because the distal ring 192' of each stent 182 can be first allowed
to expand into engagement with the vessel at the target location,
anchoring the stent in position as the remainder is deployed.
[0073] Rings 192 are preferably formed from a common piece of
material and are integrally interconnected at joints 193, making
joints 193 relatively rigid. In this embodiment, the majority of
flexibility between rings 192 is provided by struts 191 rather than
by joints 193. Alternatively, joints 193 may comprise welded
connections between rings 192 which are also fairly rigid. As a
further alternative, joints 193 may comprise hinge or spring
structures to allow greater deflection between adjacent rings 192,
as exemplified in FIGS. 10A-10B, described below.
[0074] In the embodiment of FIG. 10A-10B, stents 200 are
constructed similarly to stents 182 of FIGS. 9A-9B, including a
plurality of interconnected rings 202 having I-shaped cells 204.
However, in this embodiment, some of rings 202 are interconnected
by spring members 206 that may be elongated to increase the
distance between rings 202 and that are resiliently biased into a
shortened configuration to draw rings 202 toward each other. In one
embodiment, spring members 206 have a wave-like shape and extend
from the tip of an axial projection 208 on one ring 202 to a
concave portion 210 between axial projections 208 on the adjacent
ring 202. Of course a variety of spring configurations and
connection locations are possible, including zig-zags, coils,
spirals, accordian or telescoping structures, and the like.
Further, resilient elongatable elastomeric elements may link the
adjacent rings 202. In the illustrated embodiment, stent 200
comprises two pairs of rings 202, with the rings of each pair
interconnected by integral joints 212 as in FIGS. 9A-B and the
pairs of rings 202 being connected to each other by spring members
206. Stents 200 may alternatively include two, three, five, six or
more rings 202, and spring members 206 may interconnect all or only
a portion of rings 202.
[0075] Spring members 206 may be formed of the same or different
material as that of rings 202, depending upon the desired
performance characteristics. In addition, spring members 206 may be
biodegradable so as to erode and eventually disappear, leaving the
adjacent pairs of rings 202 unconnected.
[0076] During deployment, as outer shaft 184 is retracted to expose
a stent 200, the distal pair of rings 202' first expands into
engagement with lesion L in vessel V (FIG. 10A). Spring members 206
elongate to allow rings 202' to fully expand without pulling the
second pair of rings 202" from outer shaft 184. As retraction of
outer shaft 184 continues, the second pair of rings 202" expands
and simultaneously is drawn toward distal ring pair 182' by
contraction of spring members 206 (FIG. 10B). This results in a
predictable and constant axial spacing between the adjacent pairs
of rings 202. In addition, spring members 206 maintain rotational
alignment of rings 202 to maintain the interleaving of axial
projections 208 without overlap. As in previous embodiments,
multiple stents 200 may be deployed sequentially from delivery
catheter 180 to cover longer lesions. The ability to precisely
deploy each stent permits the relative axial spacing and rotational
position of such stents to be controlled to avoid excessive space
or overlap.
[0077] In a further embodiment, shown schematically in FIGS.
11A-11C, a delivery catheter 216 has an outer shaft 218 carrying a
plurality of stents 220. An inner shaft 222 extends through outer
shaft 218 to a nosecone 224, and a pusher shaft 226 is slidably
disposed over inner shaft 222. An anchoring balloon 228 is mounted
to inner shaft 222 proximal to nosecone 224. Anchoring balloon 228
has an axial length sufficient to frictionally engage the wall of
vessel V and remain stable so as to anchor delivery catheter 216 in
place as further described below. Preferably, anchoring balloon 228
has a length about equal to the length of one of stents 220.
[0078] In use, outer shaft 218 is retracted so that a first stent
220' is released therefrom and expands into engagement with lesion
L (FIG. 11A). Anchoring balloon 228 is then inflated until it
engages the interior of stent 220' (FIG. 11B). This not only
stabilizes delivery catheter 216, but may be used to further expand
stent 220' and/or dilate lesion L to firmly implant stent 220'.
While keeping anchoring balloon inflated within stent 220', outer
shaft 218 is further retracted to release a second stent 220",
which expands into engagement with lesion L (FIG. 11C).
Advantageously, anchoring balloon 228 stabilizes delivery catheter
216 and anchors it in position relative to first stent 220' as
second stent 220" is deployed. Second stent 220" is thus deployable
precisely at the intended spacing and rotational position relative
to first stent 220'. Anchoring balloon 228 may then be deflated and
retracted into outer shaft 218, with pressure maintained upon
pusher shaft 226 to reposition remaining stents 220 at the distal
end of inner shaft 222.
[0079] In FIG. 13A, delivery catheter 260 is positioned adjacent a
lesion L in a vessel V. Outer shaft 262 may then be retracted
(solid-tipped arrows) to begin deployment of stents 268. In FIG.
13B, outer shaft 262 has been retracted to expose two stents 268',
thus allowing them to expand within the vessel V. Coil 266 expands
along with expanding stents 268' and remains coupled with them,
thus helping prevent axial displacement ("watermelon seeding") and
in some cases rotation of stents 268' relative to one another. Once
stents 268' have been exposed, and stents 268' and coil 266 have
expanded so that at least a distal portion of the distal-most stent
268' is contacting the vessel wall, coil 266 is withdrawn from
expanded stents 268'. This may be accomplished, in one embodiment,
by rotating coil 266 (as shown by the solid-tipped arrow) to
unscrew coil 266 from stents 268'. Alternatively, coil 266 may be
configured to be simply pulled proximally without rotation to
decouple it from stents 268'. Preferably, coil 266 has a radopaque
marker at its distal tip and/or at other suitable locations along
its length to allow visualization via fluoroscopy. To facilitate
retraction of coil 266 from stents 268', coil 266 may be coated or
covered with a lubricious or other friction-reducing coating or
sleeve. Rotation is continued to retract coil 266 back into outer
shaft 262 and the remaining unexpanded stents 268. In FIG. 13C,
coil 266 has been retracted out of expanded stents 268', thus
allowing them to fully expand into contact with the inner surface
of the vessel V. The process just described may be repeated as many
times as desired to treat a long lesion L and/or multiple lesions
L.
[0080] Optionally, balloon 223 may have surface features or
coatings on its periphery that enhance retention of stents 221
thereon. Such features may include structures such as scales or
protuberances that are activated by pressurization of the balloon
so that retention is lessened when the balloon is deflated, but
heightened when the balloon is pressurized. Following stent
deployment, pressure can optionally be increased in balloon 223 for
post-dilation of stents 221 and the target lesion L. Balloon 223 is
then deflated and retracted within sheath 229 as distal pressure is
maintained against pusher 225, repositioning stents 221 near the
distal end of balloon 223 within sheath 229 for deployment at
another location, as shown in FIG. 11C.
[0081] In a further embodiment, the stents in the delivery catheter
of the invention may releasably interconnect with one another
and/or with the pusher shaft to enable greater control and
precision during deployment. As illustrated in FIG. 12, delivery
catheter 230 carries a plurality of stents 232 having a structure
much like that described above in connection with FIGS. 9A-9B.
However, in this embodiment, the axial projections 234 extending
distally and proximally from stents 232 are configured to
interconnect with concavities 236 on adjacent stents 232 until
expanded. In one embodiment, axial projections 234 have enlarged
heads 246 and concavities 236 have necks 248 that retain heads 246
within concavities 236 in the unexpanded configuration. Pusher
shaft 250 has a distal end 252 having projections 254 and
concavities 256 like those of stents 232, thus being able to
interconnect with the proximal-most stent 232'. When a stent 232"
expands, the interconnecting structures thereon are configured to
separate from the adjacent stent or pusher shaft, thus releasing
the deployed stent 232" from delivery catheter 230. In the example
shown, as stent 232" expands, heads 246" contract in size while
necks 248" enlarge, thereby allowing heads 246" on the expanded
stent to be released from concavities 236 in the adjacent
unexpanded stent, and vice versa. By exerting traction on pusher
shaft 250 during the deployment process, the line of stents 232 is
kept from moving distally relative to outer shaft 231, thus
preventing the deployed stent 232" from "watermelon seeding" as it
expands.
[0082] Various types of interconnecting structures between adjacent
stents and between the stents and the pusher shaft are possible
within the scope of the invention, including those described in
co-pending application Ser. No. 10/738,666, filed Dec. 16, 2003,
which is incorporated herein by reference. Such interconnecting
structures may also be breakable or frangible to facilitate
separation as the stent expands. In addition, a mechanism such as
an expandable balloon or cutting device may be disposed at the
distal end of delivery catheter 230 to assist in separating stents
232 upon deployment. Further, the interconnections between stents
may be different than the interconnection between the proximal-most
stent and the pusher shaft. For example, the pusher shaft may have
hooks, magnets, or other mechanisms suitable for releasably holding
and maintaining traction on the proximal end of a stent until it is
deployed.
[0083] In another embodiment, as shown in FIGS. 13A-13C, a delivery
catheter 260 includes an outer shaft 262 (or sheath), a pusher
shaft 264 slidably disposed within outer shaft 262, a plurality of
stents 268 slidably disposed within outer shaft 262, and a coil 266
extending through catheter 260 and coupled with stents 268. In
various embodiments, coil 266 may extend through pusher shaft 264
(as shown) or be disposed around pusher shaft 264. Coil 268 is
constructed of a resilient material, such as but not limited to
Nitinol.TM., spring stainless steel, resilient polymers, or other
shape memory or super-elastic materials. Coil 266 may have various
pitches, depending upon the desired spacing between adjacent loops.
Coil 266 may have a relatively high pitch (individual loops spread
relatively far apart), e.g., between about 2 and 6 loops disposed
in each stent 268. In other embodiments, coil 266 may have a lower
pitch (individual loops closer together), e.g., greater than 6
loops, or even greater than 10 loops disposed in each stent 268. Of
course, the number of loops will vary according to the length of
each stent 268, the thickness, diameter, and flexibility of coil
266, and other factors. Adjacent loops in coil 266 may also be in
contact with each other to form a tube having a substantially
continuous wall without openings. Coupling of coil 266 with stents
268 is described further below with reference to FIGS. 14-16.
[0084] In FIG. 13A, delivery catheter 260 is positioned adjacent a
lesion L in a vessel V. Outer shaft 262 may then be retracted
(solid-tipped arrows) to begin deployment of stents 268. In FIG.
13B, outer shaft 262 has been retracted to expose two stents 268',
thus allowing them to expand within the vessel V. Coil 266 expands
along with expanding stents 268' and remains coupled with them,
thus helping prevent axial displacement ("watermelon seeding") and
in some cases rotation of stents 268' relative to one another. Once
stents 268' have been exposed, and stents 268' and coil 266 have
expanded so that at least a distal portion of the distal-most stent
268' is contacting the vessel wall, coil 266 is withdrawn from
expanded stents 268'. This may be accomplished, in one embodiment,
by rotating coil 266 (as shown by the solid-tipped arrow) to
unscrew coil 266 from stents 268'. To facilitate retraction of coil
266 from stents 268', coil 266 may be coated or covered with a
lubricious or other friction-reducing coating or sleeve. Rotation
is continued to retract coil 266 back into outer shaft 262 and the
remaining unexpanded stents 268. In FIG. 13C, coil 266 has been
retracted out of expanded stents 268', thus allowing them to fully
expand into contact with the inner surface of the vessel V. The
process just described may be repeated as many times as desired to
treat a long lesion L and/or multiple lesions L.
[0085] In a preferred embodiment, adjacent stents are "keyed," or
"interleaved," to each other, meaning that fingers or other
protrusions on each end of one stent interleave with complementary
fingers/protrusions on immediately adjacent stents, as described
above in reference to FIGS. 2A-B, 4B, 9A-B, 10A-B and 12. This
feature helps prevent stents from rotating relative to one another
during deployment. Optionally, the distal end of the pusher shaft
may also include fingers/protrusions to interleave with the
proximal end of the proximal-most stent, as shown in FIG. 12 above.
Interleaving the stents with the pusher shaft helps prevent
rotation of the stents relative to the outer shaft.
[0086] Referring to FIG. 14, a stent 270 is shown in side view with
a portion of a coil 272 coupled therewith. In some embodiments,
coil 272 is threaded though openings 274 between struts 275 in
stent 270. This is shown in end-on cross section, in FIG. 15. As
described above, coil 272 may be made of any of a number of
resilient materials and may have a variety of different
configurations in various embodiments. For example, coil 272 is
shown having four loops for one stent 270, whereas in alternative
embodiments fewer or more loops per stent may be used. In an
alternative embodiment (not shown), coil 272 may be disposed around
the outside stents 270, with stents 270 being capable of sliding
axially through coil 272 or being helically (screw) driven by
rotating coil 272.
[0087] FIG. 16 shows and end-on view of another embodiment of a
stent 280 coupled with a coil 282. In this embodiment, stent 280
includes multiple, inwardly-bent struts 284, through which coil 282
is threaded. Thus, coil 282 is disposed entirely within the inner
diameter of stent 280. Such struts 284 may be adapted to remain in
the inwardly-bent configuration only when stent 280 is collapsed in
the catheter, such that struts 284 return to a position even with
the cylindrical surface of stent 280 when stent 280 expands.
Alternatively, struts 284 may remain in the inwardly bent
configuration even when stents 280 expand. Or struts 284 may be
merely elastically deflected to the inwardly bent configuration to
facilitate threading coil 282 therethrough, with struts 284 being
biased to return to a position along the cylindrical surface of
stent 280 when coil 282 is removed.
[0088] In another embodiment, illustrated in FIG. 17, a delivery
catheter 290 includes a tubular outer shaft 292 and a tubular inner
shaft 294 slidably disposed in outer shaft 202. An evertible tube
295 is attached to the distal end of inner shaft 294 and extends
distally therefrom. Evertible tube 295 has a flexible distal
portion 295' configured to evert (fold over on itself), and a
distal end 297 attached to the distal end of outer shaft 292. To
provide flexibility, at least the flexible distal portion 295' of
evertible tube 295 (and optionally all of evertible tube 295) may
be made of a flexible polymer or other bendable material and may,
in some embodiments, have thinner walls than inner shaft 294 or
outer shaft 292. A pusher shaft 300 is slidably disposed in inner
shaft 294, and a plurality of stents 302 are slidably disposed
within inner shaft 294 distally of pusher shaft 300. When outer
shaft 292 is retracted (slid proximally) relative to inner shaft
294, the flexible distal portion 295' of evertible tube 295 everts
(i.e., bends outward and folds back on itself) and thus follows
outer shaft 292 proximally. This process of sliding outer shaft 292
proximally to evert and pull flexible distal portion 295'
proximally causes stents 302' to deploy out of the distal end 299
of the delivery catheter 290.
[0089] Axial displacement of each stent 302' is controlled (and
watermelon seeding is avoided) due to frictional engagement with
the inner surface 296 of evertible tube 295. To enhance retention
of stents 302 in evertible tube 295, inner surface 296 may include
adherent coatings or other surface features adapted to engage and
retain stents 302. For example, inner surface 296 may comprise a
layer or coating of sticky, tacky or otherwise high-friction
material. Alternatively, inner surface 296 may include
friction-inducing features such as roughened areas, bumps, spines,
bristles, ridges, ribs, channels, grooves, or random surface
irregularities. As flexible distal portion 294' everts and moves
proximally, stents 302' peel off of adherent surface 296 in a
controlled fashion.
[0090] In an alternative embodiment, shown in FIG. 18, stents 308
are partially embedded in an inner surface 306 of an evertible tube
304. For example, evertible tube 304 may have an inner surface 306
that softens and/or becomes malleable when heated. When stents 308
are loaded in evertible tube 304, inner surface 306 is heated so
that stents 308 are partially and releasably embedded in inner
surface 306, with portions of the softened surface material
extending through the openings 307 between struts 309 in stent 308.
To deploy stents 308, the distal end of evertible tube 304 is
everted as described above, peeling inner surface 306 away from
each stent 308 to release it into the vessel. Because stents 308
are embedded in inner surface 306, they are not fully released from
the catheter until evertible tube 304 is peeled completely off of
stent 308, at which time the distal end of stent 308 has expanded
into contact with the vessel. Uncontrolled axial displacement of
stent 308 is thus avoided.
[0091] In the embodiment shown in FIG. 19, an evertible tube 314
includes multiple retention structures 316 on an inner surface 319,
which extend through openings 317 between struts 315 in a stent 318
to releasably hold stent 318. Retention structures 316 are
preferably adapted to extend through openings 317 and abut the
inner surfaces of struts 315 to provide secure but releasable
engagement with stents 318. When the distal end of evertible tube
314 is peeled back to deploy stents 318, retention structures 316
are adapted to be pulled out of openings 317 to release stent 318.
Retention structures 316 may comprise, for example, multiple
mushroom-shaped protrusions (as shown) or alternatively, or
alternatively, L-shaped, T-shaped, barbed, pyramidal, arrow-shaped,
linear or hook-shaped protrusions.
[0092] Retention structures 316 may be integrally formed with
evertible tube 314 and made of the same flexible polymer, or
alternatively may be separate structures of polymer, metal wire or
other flexible material attached to evertible tube 314. Such
retention structures may be positioned to engage stent 318 at
various locations along its length, e.g. at several locations along
the entire length of the stent, e.g. near the proximal and distal
ends (as shown), only near the proximal end, only near the distal
end, only at the middle, or at another discreet location.
[0093] Referring now to FIGS. 20-23, a further embodiment of a
prosthesis delivery catheter according to the invention will be
described. In this embodiment, delivery catheter 400 has a tubular
outer shaft 402, a pusher shaft 404 slidably disposed within outer
shaft 402, and an inner shaft 406 slidably disposed within pusher
shaft 402. Inner shaft 406 has a guidewire lumen extending axially
therethrough for receiving a guidewire GW. A plurality of
self-expanding stents 420 (not shown in FIG. 20A) are slidably
disposed within outer shaft 402 distally of pusher shaft 404, which
can be used to exert a distal force against such stents for the
deployment thereof, as described further below. A nosecone 407 is
fixed to the distal end of inner shaft 406 and has a
proximally-facing aperture 409 in its proximal end. Outer shaft 402
has a distal end 408 to which is attached a control member 410
defining an interior 411 in which a stent 420 may be received.
Control member 410 has a plurality of flexible tines 412 extending
distally and having free distal ends 414 removably received within
aperture 409. A wall 416 extending circumferentially around
aperture 409 retains flexible tines 412 within aperture 409.
Nosecone 407 is movable distally relative to control member 410 to
release tines 412 from aperture 409.
[0094] Control member 410 may be constructed of a polymer, metal,
or other flexible and resilient material. Tines 412 are deflectable
outwardly under the expansion force of stents 420. Tines 412 are
preferably biased inwardly into general alignment with the
longitudinal axis of delivery catheter 400 such that free distal
ends 414 remain positioned inwardly near inner shaft 406 even after
release from aperture 409. Tines 412 may include a
friction-enhancing coating, texture, cover, or other surface
features on their inwardly-facing surfaces to create more friction
with stents 420. Alternatively, a lubricious coating may be
provided on the inner or outer surfaces of tines 412 for greater
slidability. Tines 412 may have an axial length which is less than
or equal to the length of one stent 420, a length greater than the
length of one stent 420, or a length as long as the length of 2, 3
or more stents 420. Aperture 409 may be relatively shallow, as
shown, so as to receive only the free distal ends 414 of tines 412,
or may be somewhat deeper so that a portion or substantially all of
the length of tines 412 is disposed within aperture 409.
[0095] As shown in FIGS. 21A-21E, in use, delivery catheter 400 is
positioned in a vessel at the treatment site with tines 412
disposed within aperture 409 on nosecone 407. Nosecone 407 is then
advanced distally relative to control member 410 (or outer shaft
402 is retracted proximally relative to nosecone 407) to release
tines 412 from aperture 409 as shown in FIG. 21B. Outer shaft 402
is then retracted relative to pusher shaft 404 (or pusher shaft 404
may be pushed distally) to advance one or more stents 420 out of
outer shaft 402 into control member 410, as shown in FIG. 21C.
Tines 412 exert an inward force on stents 420 to resist, but not
prevent, the expansion thereof. This slows down the rate of stent
expansion and also provides frictional resistance between tines 412
and the outer surface of stent 420, thereby reducing the tendency
of the stent to jump distally as it expands. As shown in FIG. 21D,
tines 412 preferably have a length selected so that before a first
stent 420A is fully expanded and released from control member 410,
a second stent 420B is at least partially contained within control
member 410. In this way multiple stents 420 may be deployed
end-to-end with a desired degree of inter-stent spacing and without
overlaps or excessive gaps. Outer shaft 402 is retracted until the
desired number of stents 420 has been deployed at the treatment
site. Outer shaft 402 and pusher shaft 404 are then retracted
together to slidably decouple tines 412 from the deployed stents
420, as shown in FIG. 21E. Nosecone 407 may then be retracted
through the deployed stents until tines 412 are positioned in
aperture 409. The device can then be repositioned at a new
treatment site for additional deployments.
[0096] FIG. 22 illustrates an alternative embodiment of control
member 410, in which multiple webs 422 are disposed between tines
412. Webs 422 are preferably made of a flexible, resilient and
distensible elastomer configured to radially expand or stretch
under the expansion force of a stent 420. Webs 422 may comprise a
substantially continuous, non-porous sheet, or may have openings,
or may be comprised of a plurality of woven strands. Optionally,
webs 422 may extend over the outer and/or inner surfaces of tines
412, and may connect to form a continuous tubular structure. Webs
422 may serve to provide additional resistance to stent expansion,
may provide a protective surface around stent 420 and/or tines 412,
and may also have lubricity on their outer and/or inner surfaces to
facilitate withdrawal of tines 412 from stents 420 following
deployment.
[0097] FIG. 23 illustrates a further embodiment in which control
member 410 comprises a single distensible tubular member 424 rather
than having tines 412. Tubular member 424 is preferably a flexible,
resilient, and distensible elastomer configured to stretch or
expand radially under the expansion force of a stent 420. Tubular
member 424 is normally in a radially contracted, generally
cylindrical shape without stents 420 positioned therein, with its
distal end 426 adapted for positioning in aperture 409 in nosecone
407. As with web 422, tubular member 424 may be a substantially
continuous, non-porous sheet, or it may have openings, or it may be
comprised of a plurality of woven strands. In addition, tubular
member 424 may have a lubricious outer or inner surface to
facilitate withdrawal from stents 420 following deployment. The
inner surface of tubular member 424 may also include friction
enhancing coatings, textures, or features to enhance retention of
stents 420 therein.
[0098] While the above is a complete description of the preferred
embodiments of the invention, various alternatives, modifications,
improvements and additions are possible without departing from the
scope thereof, which is defined by the claims.
* * * * *