U.S. patent application number 12/556997 was filed with the patent office on 2010-03-18 for stents and catheters having improved stent deployment.
This patent application is currently assigned to EV3 INC.. Invention is credited to Sandra Kallio, Rick Kravik, Richard Kusleika, Bryan Matthew Ladd, Lucas Tradd Schneider.
Application Number | 20100070015 12/556997 |
Document ID | / |
Family ID | 41416212 |
Filed Date | 2010-03-18 |
United States Patent
Application |
20100070015 |
Kind Code |
A1 |
Schneider; Lucas Tradd ; et
al. |
March 18, 2010 |
STENTS AND CATHETERS HAVING IMPROVED STENT DEPLOYMENT
Abstract
An implant delivery system and method comprises an implant, for
example, a stent, and a delivery catheter. The stent has a scaffold
with a coating or a shell that retains the scaffold in a collapsed
configuration. The coating or shell is made of a material that
dissolves or biodegrades upon exposure to a dissolution or
biodegradation media. The stent is used with an implant delivery
system which has a catheter with a catheter, wherein the stent is
mounted on the catheter shaft. The catheter shaft is configured to
be withdrawn through the patient's vessel when the scaffold is in
its expanded configuration. Advantageously, the implant is thereby
prevented from changing length during implant delivery and implant
deployment.
Inventors: |
Schneider; Lucas Tradd;
(Rogers, MN) ; Ladd; Bryan Matthew; (Minneapolis,
MN) ; Kusleika; Richard; (Eden Prairie, MN) ;
Kravik; Rick; (Champlin, MN) ; Kallio; Sandra;
(Circle Pines, MN) |
Correspondence
Address: |
RISSMAN HENDRICKS & OLIVERIO, LLP
100 Cambridge Street, Suite 2101
BOSTON
MA
02114
US
|
Assignee: |
EV3 INC.
Plymouth
MN
|
Family ID: |
41416212 |
Appl. No.: |
12/556997 |
Filed: |
September 10, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61095766 |
Sep 10, 2008 |
|
|
|
Current U.S.
Class: |
623/1.11 ;
623/1.2; 623/1.42 |
Current CPC
Class: |
A61F 2/966 20130101;
A61F 2210/0004 20130101; A61F 2/95 20130101; A61F 2/958 20130101;
A61F 2/962 20130101; A61F 2002/9665 20130101; A61F 2002/9505
20130101; A61F 2/844 20130101 |
Class at
Publication: |
623/1.11 ;
623/1.42; 623/1.2 |
International
Class: |
A61F 2/84 20060101
A61F002/84; A61F 2/82 20060101 A61F002/82 |
Claims
1. A stent for insertion into a body lumen, comprising: a scaffold
having a collapsed and a diametrically expanded configuration; and
a coating or a shell surrounding the scaffold that retains the
scaffold in its collapsed configuration, said coating or shell made
of a material that dissolves or biodegrades upon exposure to a
dissolution or biodegradation media; wherein the scaffold is
expanded from its collapsed to its expanded configuration through
exposure of the coating or shell to the dissolution or
biodegradation media.
2. The stent of claim 1, wherein the coating comprises a material
selected from the group consisting of sugar, carbowax, polyethylene
oxide, and poly vinyl alcohol.
3. The stent of claim 1, wherein the coating or shell comprises a
bioactive material selected from the group consisting of
antirestenotic agents, anti-inflammatory agents, antithrombotic
agents, antiatheromatic (antiatheroma) agents, and antioxidative
agents.
4. The stent of claim 1, wherein the shell comprises a material
selected from the group consisting of sugar, carbowax, polyethylene
oxide, poly vinyl alcohol, poly lactic acid (PLA), poly glycolic
acid (PGA), poly lactic glycolic acid (PLGA), poly
(.epsilon.-caprolactone) copolymers, polydioxanone, poly(propylene
fumarate) poly(trimethylene carbonate) copolymers, polyhydroxy
alkanoates, polyphosphazenes, polyanhydrides, poly(ortho esters),
poly(amino acids), or "pseudo"-poly(amino acids).
5. The stent of claim 1, wherein the shell comprises tubing into
which the scaffold is inserted, or a film which is wrapped around
the compressed scaffold.
6. The stent of claim 5, wherein the shell comprises a longitudinal
slit or is perforated.
7. The stent of claim 1, wherein the scaffold is
self-expanding.
8. The stent of claim 1, wherein the scaffold is
balloon-expandable.
9. An implant delivery system for deploying a stent in a patient's
vessel, the system comprising: a catheter having a catheter shaft;
a stent mounted on the catheter shaft, said stent comprising a
scaffold having a collapsed configuration and a diametrically
expanded configuration; and a coating or a shell surrounding the
scaffold and retaining the scaffold in its collapsed configuration,
said coating or shell made of a material that dissolves or
biodegrades upon exposure to a dissolution or biodegradation media;
wherein the scaffold is expanded from its collapsed to its expanded
configuration through exposure of the coating or shell to the
dissolution or biodegradation media and wherein the catheter shaft
is configured to be withdrawn through the patient's vessel when the
scaffold is in its expanded configuration.
10. The system of claim 9, wherein the stent is self-expanding.
11. The system of claim 9, further comprising a slidable tubular
sheath surrounding the stent in the collapsed configuration on the
catheter shaft, said tubular sheath protecting the coating or a
shell from exposure to the dissolution or biodegradation media.
12. The system of claim 9, further comprising an inflatable balloon
disposed between the stent and the catheter shaft, said balloon
fracturing the coating or shell upon inflation.
13. The system of claim 12, wherein the balloon is sealingly
attached to both a proximal end and a distal end of the catheter
shaft.
14. The system of claim 12, further comprising a slidable tubular
sheath surrounding the stent in the collapsed configuration on the
catheter shaft, wherein the balloon is constructed such that a
force of friction of the balloon in contact with the stent is
greater than a force of friction of the sheath in contact with the
stent.
15. A method for delivering a stent to a treatment site, comprising
the steps of: providing an implant delivery system having a stent
mounted on a catheter shaft, said stent having a scaffold with a
coating or a shell surrounding the scaffold and retaining the
scaffold in its collapsed configuration, and a tubular sheath
surrounding the stent in the collapsed configuration on the
catheter shaft; advancing the implant delivery system to the
treatment site; withdrawing the tubular sheath to expose the
coating or shell to a dissolution or biodegradation media; and
withdrawing the catheter shaft from the treatment site.
16. The method of claim 15, wherein the stent is
self-expanding.
17. The method of claim 15, wherein the delivery system further
comprises a balloon interposed between the stent and the catheter
shaft, the method further comprising the step of inflating the
balloon to cause expansion of the stent before withdrawing the
catheter shaft.
18. The method of claim 17, wherein inflating the balloon comprises
pressurizing a balloon inflation lumen with fluid or gas until a
force of sliding friction of the stent against the balloon exceeds
a force of sliding friction of the stent against the tubular
sheath.
19. A method for delivering a stent to a treatment site, comprising
the steps of: providing an implant delivery system having a stent
mounted on a catheter shaft, a balloon interposed between the stent
and the catheter shaft, and a tubular sheath surrounding the stent
in the collapsed configuration on the catheter shaft; advancing the
implant delivery system to the treatment site; inflating the
balloon to cause expansion of the stent before withdrawing the
tubular sheath; withdrawing the tubular sheath; and withdrawing the
catheter shaft from the treatment site.
20. The method of claim 19, wherein the stent is
self-expanding.
21. The method of claim 19, wherein inflating the balloon comprises
pressurizing a balloon inflation lumen with fluid or gas until a
force of sliding friction of the stent against the balloon exceeds
a force of sliding friction of the stent against the tubular
sheath.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
application Ser. No. 61/095,766, filed Sep. 10, 2008, the entire
content of which is incorporated herein by reference in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to systems for delivering an
implant to a site in a body lumen. More particularly, this
invention pertains to delivery systems for a vascular implant such
as a self-expanding stent.
BACKGROUND OF THE INVENTION
[0003] Stents are widely used for supporting a lumen structure in a
patient's body. For example, stents may be used to maintain patency
of a coronary artery, carotid artery, cerebral artery, femoral
artery, other blood vessels including veins, or other body lumens
such as the ureter, urethra, bronchus, esophagus, or other
passage.
[0004] Stents are commonly metallic tubular structures made from
stainless steel, Nitinol, Elgiloy, cobalt chrome alloys, tantalum,
and other metals, although polymer stents are known. Stents can be
permanent enduring implants, or can be bioabsorbable at least in
part. Bioabsorbable stents can be polymeric, bio-polymeric,
ceramic, bio-ceramic, or metallic, and may elute over time
substances such as drugs. Non-bioabsorbable stents may also release
drugs over time. Stents are passed through a body lumen in a
collapsed state. At the point of an obstruction or other deployment
site in the body lumen, the stent is expanded to an expanded
diameter to support the lumen at the deployment site.
[0005] In certain designs, stents are comprised of tubes having
multiple through holes or cells that are expanded by inflatable
balloons at the deployment site. This type of stent is often
referred to as a "balloon expandable" stent. Stent delivery systems
for balloon expandable stents are typically comprised of an
inflatable balloon mounted on a two lumen tube. The stent delivery
system with stent compressed thereon can be advanced to a treatment
site over a guidewire, and the balloon inflated to expand and
deploy the stent.
[0006] Other stents are so-called "self expanding" stents and do
not use balloons to cause the expansion of the stent. An example of
a self-expanding stent is a tube (e.g., a coil of wire or a tube
comprised of cells) made of an elastically deformable material
(e.g., a superelastic material such a nitinol). Some self expanding
stents are also comprised of tubes having multiple through holes or
cells. This type of stent is secured in compression in a collapsed
state to a stent delivery device. At the deployment site, stent
compression is released and restoring forces within the stent cause
the stent to self-expand to its enlarged diameter.
[0007] Other self-expanding stents are made of so-called
shape-memory metals. Such shape-memory stents experience a phase
change at the elevated temperature of the human body. The phase
change results in expansion from a collapsed state to an enlarged
state.
[0008] A very popular type of self expanding stent is a cellular
tube made from self-expanding nitinol, for example, the EverFlex
stent from ev3, Inc. of Plymouth, Minn. Cellular stents are
commonly made by laser cutting of tubes, or cutting patterns into
sheets followed by or preceded by welding the sheet into a tube
shape, and other methods. Another delivery technique for a self
expanding stent is to mount the collapsed stent on a distal end of
a stent delivery system. Such a system can be comprised of an outer
tubular member and an inner tubular member. The inner and outer
tubular members are axially slideable relative to one another. The
stent (in the collapsed state) is mounted surrounding the inner
tubular member at its distal end. The outer tubular member (also
called the outer sheath) surrounds the stent at the distal end.
[0009] Prior to advancing the stent delivery system through the
body lumen, a guide wire is first passed through the body lumen to
the deployment site. The inner tube of the delivery system is
hollow throughout at least a portion of its length such that it can
be advanced over the guide wire to the deployment site. The
combined structure (i.e., stent mounted on stent delivery system)
is passed through the patient's lumen until the distal end of the
delivery system arrives at the deployment site within the body
lumen. The deployment system and/or the stent may include
radiopaque markers to permit a physician to visualize positioning
of the stent under fluoroscopy prior to deployment. At the
deployment site, the outer sheath is retracted to expose the stent.
The exposed stent is free to self-expand within the body lumen.
Following expansion of the stent, the inner tube is free to pass
through the stent such that the delivery system can be removed
through the body lumen leaving the stent in place at the deployment
site.
[0010] In prior art devices, high forces may be required to retract
the outer sheath so as to permit the stent to self expand. Delivery
systems designed to withstand high retraction forces can be bulky,
can have reduced flexibility and can have unacceptable failure
rates. In addition, due to frictional forces between the stent and
the outer sheath in prior art devices the stent may change in
length during deployment, either in overall length or locally over
regions of the stent. For example, long stents, thin stents, stents
with high axial flexibility parallel to the central axis of the
stent, or stents with a large amount of expansile force, when
compressed in a sheath, tend to change in length as the outer
sheath is withdrawn from the inner tubular member. Also, prior art
delivery systems can be moved when the implant is partially
deployed, resulting in undesirable regional length changes in the
implanted device. Changes in stent length during stent deployment
can prevent a stent from being properly deployed over the intended
treatment area, can compromise stent fracture resistance and can
compromise stent fatigue life.
[0011] What is needed is a stent delivery system that permits low
force and precise delivery of stents without altering the intended
length of the stent.
SUMMARY OF THE INVENTION
[0012] According to one aspect of the present invention, a stent
includes a scaffold and a coating that restrains diametrical
expansion of the scaffold. Dissolution or biodegradation of the
coating allows the stent to expand or be expanded.
[0013] According to another aspect of the present invention, a
stent includes a scaffold and a shell that restrains diametrical
expansion of the scaffold. Dissolution or biodegradation of the
shell allows the stent to expand or be expanded.
[0014] According to other aspects of the present invention, an
implant delivery system includes a stent with a scaffold and a
coating or shell that restrains diametrical expansion of the
scaffold and a catheter on which the stent is mounted in a
collapsed, restrained state. Upon exposure to dissolution fluid or
biodegradation media, dissolution or biodegradation of the coating
or shell allows the stent to expand or be expanded.
[0015] According to other aspects of the present invention, an
implant delivery system includes a stent with a scaffold and a
coating that restrains diametrical expansion of the scaffold and an
inflatable balloon mounted on the catheter beneath the stent. Upon
inflating the balloon the coating or shell is compromised or
fractured and the stent self-expands or is further expanded by
further inflation of the balloon. Exposure to dissolution fluid or
biodegradation media causes fragments of the coating or shell to
dissolve or biodegrade.
[0016] According to other aspects of the present invention, an
implant delivery system includes a stent with a scaffold and a
coating that restrains diametrical expansion of the scaffold and a
slidable tubular sheath surrounding the catheter and restrained
stent. Upon proximal withdrawal of the sheath the coating or shell
is exposed to dissolution fluid or biodegradation media and
dissolution or biodegradation of the coating or shell allows the
stent to expand or be expanded. Exposure to dissolution fluid or
biodegradation media causes fragments of the coating or shell to
dissolve or biodegrade.
[0017] According to yet other aspects of the present invention, an
implant delivery system includes a stent with a scaffold and a
coating that restrains diametrical expansion of the scaffold, and a
slidable tubular sheath surrounding the catheter, an inflatable
balloon and a restrained stent. The stent is deployed by proximal
withdrawal of the sheath followed by inflation of the balloon to
compromise or fracture the coating or shell. The stent then
self-expands or is further expanded by further inflation of the
balloon. Exposure to dissolution fluid or biodegradation media
causes fragments of the coating or shell to dissolve or
biodegrade.
[0018] In yet another aspect of the present invention, an implant
delivery system having a stent with a scaffold and a coating that
restrains diametrical expansion of the scaffold is delivered to a
treatment site, a slidable tubular sheath surrounding the catheter,
an inflatable balloon and a restrained stent, is delivered to a
treatment site. At the treatment site, the balloon is inflated
until the sliding friction of the stent against the balloon is
greater than the sliding friction of the stent against the outer
sheath. The outer sheath is then retracted to expose the stent
which self expands upon exposure. The stent may be further expanded
by further inflation of the balloon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The above and further advantages of the invention may be
better understood by referring to the following description in
conjunction with the accompanying drawings in which:
[0020] FIG. 1A illustrates a schematic side view of an implant
delivery system having features in accordance with the principles
of the present disclosure;
[0021] FIGS. 1B, 1C and 2 illustrate schematic cross sectional
views of stent and stent implant system embodiments having features
in accordance with the principles of the present disclosure;
[0022] FIGS. 3A to 3C, 4, and 5A to 5D illustrate schematic cross
sectional views of implant delivery systems having features in
accordance with the principles of the present disclosure;
[0023] FIGS. 6A, 6B, 6C, 7, 8A, 8B, 8C and 8D illustrate schematic
side views of implant delivery systems having features in
accordance with the principles of the present disclosure.
DETAILED DESCRIPTION
[0024] Embodiments that are examples of how inventive aspects in
accordance with the principles of the present invention will now be
described in more detail with reference to the drawings. It is to
be understood that both the foregoing general description and the
following detailed description are exemplary and explanatory only
and are not restrictive of the broad inventive aspects disclosed
herein. It will also be appreciated that the inventive concepts
disclosed herein are not limited to the particular stent
configurations disclosed herein, but are instead applicable to any
number of different stent configurations.
[0025] FIGS. 1A and 1B illustrate implant delivery system 1
comprised of stent 10, catheter shaft 5 with hub 3 and guidewire
lumen 6 extending through catheter shaft and hub. Catheter shaft 5
is relatively flexible, may be comprised of a polymeric material
such as nylon or PEBAX, and may range in length from 60 cm to 300
cm. Catheter outside diameter may range from about 2 Fr to about 10
Fr. Guidewire lumen 6 diameter may be large enough to allow passage
of guidewires ranging in diameter from 0.009'' to 0.038''. Hub 3 is
sealingly attached to catheter shaft 5, is adapted to reversibly
connect to other medical devices (for example by means of a luer
fitting) and may be comprised of polycarbonate. Stent 10 is
comprised of scaffold 12 and coating 14. In various embodiments
scaffold may be self expanding, balloon expandable, tubular,
comprised of cells, comprised of coils, comprised of metals,
polymer, ceramics, or other materials, or may have other
characteristics. In one embodiment scaffold 12 includes Nitinol
tubing having cellular openings and having suitable heat treatment
to cause scaffold 12 to self-expand at human body temperatures.
Scaffold 12 configurations suitable for the invention include but
are not limited to tapered, flared, braided, bifurcated,
fracturable, mesh covered, scaffolds comprised of radiopaque
markers, and other scaffolds as are known in the art. Long
scaffolds are especially suited to the invention. Implant delivery
systems 1 for scaffolds having lengths of from 20-400 mm are
contemplated. In one embodiment, implant delivery system 1 can
deliver and deploy a 30 mm scaffold. In other embodiments, implant
delivery system 1 can deliver and deploy a 40 mm, 60 mm, 80 mm, 100
mm, 120 mm, 150 mm, 180 mm, 200 mm, 250 mm, 300 mm or 350 mm
scaffold. As shown in FIGS. 1B and 1C, coating 14 may optionally be
applied to catheter shaft 5 outer diameter along some or all of the
scaffold length and may be applied to at least one of outer
surface, inner surface, or through thickness of scaffold 12. In
some embodiments coating 14 covers the exposed edges of stent 10 so
as to form a smooth exterior coated stent surface. Coating 14, when
applied and hardened, maintains stent 10 at an unexpanded diameter
and a fixed length prior to stent deployment. Coating 14 may cause
stent to adhere directly to inner member. Coating 14 may be
comprised of biodegradable materials, or may be comprised of
materials that dissolve in the body or in the bloodstream. In some
embodiments coating 14 includes sugar, carbowax, polyethylene
oxide, poly vinyl alcohol or other materials. Coating 14 may be
applied by spray, dip, or other processes to unexpanded stent and
allowed to harden, may be applied to expanded stent and allowed to
harden after stent is compressed, may be applied to and hardened on
expanded stent so as to maintain scaffold in an unexpanded diameter
after subsequent stent compression, or may be applied and hardened
by other methods.
[0026] In some embodiments coating 14 can dissolve or biodegrade
over time so as to release the scaffold. In some embodiments
coating 14 can dissolve or biodegrade when in contact with blood to
allow expansion of scaffold 12. Upon contact with dissolution or
biodegradation causing media, scaffold release times of 0.5 to 300
seconds are contemplated. In one embodiment, scaffold release time
is approximately 1 second. In other embodiments, scaffold release
time is approximately 2, 5, 10, 20, 30, 45, 60, 90, 120, 150, 180
or 240 seconds. In some embodiments a change in scaffold 12 length
of less than 10% upon expansion from a contracted to an expanded
configuration is contemplated. In other embodiments, scaffold 12
length change upon expansion from a contracted to an expanded
configuration is less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2% or
1%.
[0027] Coating 14 may be comprised of bioactive materials such as
antirestenotic agents, anti-inflammatory agents, antithrombotic
agents, antiatheromatic (antiatheroma) agents, antioxidative
agents, or other agents. Bioactive coating materials may be
released from the coating into surrounding tissue or blood and may
have a diagnostic or therapeutic action on tissue or blood.
[0028] An exemplary method of using a stent 10 with implant
delivery system 1 is now described. A guidewire is advance into a
patient's femoral artery using known techniques, through a
patient's vessel and past a treatment site. Stent 10 is loaded onto
implant delivery system 1 and introduced over the guidewire into
the patient's vessel. Stent 10 is restrained from expanding by
coating 14. The stent and implant delivery system combination is
advanced over the guidewire and through the patients vessel until
stent 10 is located at a treatment site, for example within a
stenosis in a femoral artery. Stent 10 is deployed by allowing
coating 14 to dissolve or to biodegrade thereby allowing scaffold
12 to self-expand. Catheter shaft 5 is then withdrawn through the
patient's vessel and out of the patient's body. Any of coating that
is pinned between scaffold and the vessel, attached to scaffold, or
which embolizes from the treatment site dissolves or biodegrades
over time. Scaffold 10 does not change length upon deployment
because the scaffold is immobilized on catheter shaft 5 by coating
14 during delivery to the treatment site and because there is no
sheath to draw past the stent during deployment.
[0029] FIG. 2 illustrates implant delivery system 1 comprised of
stent 20, catheter shaft 5 with hub (not shown) and guidewire lumen
6 extending through catheter shaft and hub. Stent 20 includes
scaffold 12 and shell 24. Shell 24 surrounds scaffold 12 and may
form a smooth exterior surface over stent 20. Shell 24 maintains
stent 20 at an unexpanded diameter prior to stent deployment and
may be comprised of biodegradable materials, or may be comprised of
materials that dissolve in the body or in the bloodstream. In some
embodiments shell 24 includes sugar, carbowax, polyethylene oxide,
poly vinyl alcohol, poly lactic acid (PLA), poly glycolic acid
(PGA), poly lactic glycolic acid (PLGA), poly (c-caprolactone)
copolymers, polydioxanone, poly(propylene fumarate)
poly(trimethylene carbonate) copolymers, polyhydroxy alkanoates,
polyphosphazenes, polyanhydrides, poly(ortho esters), poly(amino
acids), or "pseudo"-poly(amino acids).
[0030] The resorption or dissolution time of shell 24 can be varied
by varying the ratio of constituent materials or by other means.
The shell material may be axially or biaxially oriented or may have
other structure. Shell 24 may be comprised of tubing into which
scaffold 12 is inserted, or of film which is wrapped around
compressed scaffold, or other structures, and may be applied by
other application methods. Shell may be slit, perforated, have a
high ability to stretch, may soften abruptly or substantially when
heated to near body temperature, or have other characteristics to
aid with shell fracture during scaffold expansion.
[0031] In some embodiments shell 24 can dissolve or biodegrade over
time so as to release scaffold. In some embodiments shell 24 can
dissolve or biodegrade when in contact with blood to allow
expansion of scaffold 12. Upon contact with dissolution or
biodegradation causing media, scaffold release times of 0.5 to 300
seconds are contemplated. In one embodiment, the scaffold release
time is approximately 1 second. In other embodiments, the scaffold
release time is approximately 2, 5, 10, 20, 30, 45, 60, 90, 120,
150, 180 or 240 seconds. In some embodiments a change in scaffold
12 length of less than 10% upon expansion from a contracted to an
expanded configuration is contemplated. In other embodiments,
scaffold 12 length change upon expansion from a contracted to an
expanded configuration is less than 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%
or 1%.
[0032] Shell 24 may be comprised of bioactive materials such as
antirestenotic agents, anti-inflammatory agents, antithrombotic
agents, antiatheromatic (antiatheroma) agents, antioxidative
agents, or other agents. Bioactive coating materials may be
released from the coating into surrounding tissue or blood and may
have a diagnostic or therapeutic action on tissue or blood.
[0033] An exemplary method of using a stent 20 with implant
delivery system 1 is now described. A guidewire is advance into a
patient's femoral artery using known techniques, through a
patient's vessel and past a treatment site. Stent 20 is loaded onto
implant delivery system 1 and introduced over the guidewire into
the patient's vessel. Stent 20 is restrained from expanding by
shell 24. The stent and implant delivery system combination is
advanced over the guidewire and through the patients vessel until
stent 20 is located at a treatment site, for example within a
stenosis in a carotid artery. Stent 20 is deployed by allowing
shell 24 to dissolve or to biodegrade thereby allowing scaffold to
self-expand. Shell may fracture upon expansion of scaffold, and
such fracture may be assisted by preplaced slits, slots, local
thinning of wall thickness of shell, or other means. Catheter shaft
5 is then withdrawn through the patient's vessel and out of the
patient's body. Any of shell 24 that is pinned between scaffold and
the vessel, attached to scaffold, or which embolizes from the
treatment site dissolves or biodegrades over time. Scaffold 12 does
not change length on deployment because the scaffold is immobilized
on catheter shaft 5 during delivery to the treatment site and
because there is no sheath to draw past the stent during
deployment
[0034] FIGS. 3A to 3C illustrate an example of a Rapid Exchange
(RX) delivery system 30 comprised of stent 32, catheter shaft 35
having balloon inflation lumen (not shown), guidewire lumen 36,
guidewire lumen exit skive 39 and inflation hub 33, and balloon 31.
Catheter shaft 35 is relatively flexible, may be comprised of a
polymeric material such as nylon or PEBAX, and may range in length
from 60 cm to 300 cm. Catheter shaft 35 outside diameter may range
from about 2 Fr to about 10 Fr. Guidewire lumen 36 diameter may be
large enough to allow passage of guidewires ranging in diameter
from 0.009'' to 0.038''. Hub 33 is sealingly attached to catheter
shaft 35, is adapted to reversibly connect to other medical devices
(for example by means of a luer fitting) and may be comprised of
polycarbonate. Balloon 31 is sealingly attached at both proximal
and distal ends to catheter shaft 35 and may be comprised of
biaxially oriented nylon, polyester, Pebax, polyolefin, or other
materials. Stent 32 may be comprised of stents 10, 20 or other
stents, is shown in an unexpanded configuration in FIGS. 3A and 3B
and in an expanded configuration in FIG. 3C. Stent 32 is deployed
by connecting an inflation device (not shown) to hub 33 and
pressurizing balloon inflation lumen with fluid or gas so as to
expand balloon 31 thereby expanding stent 32. In some embodiments
stent 32 is fully expanded into contact with vessel wall by
expansion of balloon 31.
[0035] When balloon 31 is expanded beneath stent 10, the
restraining force of coating 14 is overcome by balloon pressure and
the coating fractures, allowing stent 10 to expand. When balloon 31
is expanded beneath stent 20, the restraining force of shell 24 is
overcome by balloon pressure and the shell fractures, allowing
stent 20 to expand.
[0036] An exemplary method of using stent 32 with delivery system
30 is now described. A guidewire is advanced into a patient's
femoral artery using known techniques, through a patient's vessel
and past a treatment site. A stent 32 (for example stent 10, 20) is
loaded onto implant delivery system 30 and introduced over the
guidewire into the patient's vessel. The stent and implant delivery
system combination is advanced over the guidewire and through the
patient's vessel until the stent is located at a treatment site,
for example within a stenosis in a carotid artery. Stent 10, 20 is
deployed by inflating balloon 31 thereby causing coating 14 or
shell 24 to fracture and stent to expand. Catheter 35 is then
withdrawn through the patient's vessel and out of the patient's
body. Any of coating or shell that is pinned under scaffold, or
which embolizes, dissolves/degrades over time. Stent 10, 20 does
not change length on deployment because the stent is immobilized on
catheter shaft 35 during delivery to the treatment site and because
there is no sheath to draw past the stent during deployment.
[0037] FIG. 4 illustrates an example of an Over The Wire (OTW)
delivery system 40 comprised of stent 42, catheter shaft 45 having
balloon inflation lumen (not shown), guidewire lumen (not shown)
and manifold 47, and balloon 41. Manifold 47 includes guidewire
lumen exit port 49 and inflation hub 43. Catheter shaft 45,
guidewire lumen, balloon 41, and inflation hub 43 have
substantially the same construction, dimensions, and function as
catheter shaft 35, guidewire lumen 36, balloon 31, and inflation
hub 33 described above in conjunction with FIGS. 3A to 3C. Manifold
47 is sealingly attached to catheter shaft 45 and may be comprised
of polycarbonate. Guidewire lumen exit port 49 and inflation hub 43
are adapted to reversibly connect to other medical devices (for
example by means of a luer fitting). (for example stent 10, 20),
Stent 42 may be comprised of stents 10, 20 or other stents and is
shown in an expanded configuration in
[0038] FIG. 4. Stent 42 is deployed by connecting inflation device
(not shown) to hub 43 and pressurizing balloon inflation lumen with
fluid or gas so as to expand balloon 41 thereby expanding stent 42.
In some embodiments stent 42 is fully expanded into contact with
vessel wall by expansion of balloon 41.
[0039] The methods of using and the benefits of using Over The Wire
(OTW) delivery system 40 are substantially the same as those
described above for Rapid Exchange (RX) delivery system 30.
[0040] FIGS. 5A, 5B, 5C and 5D illustrate further embodiments of
implant delivery systems having features in accordance with the
principles of the present disclosure. FIG. 5A illustrates implant
delivery system 50 comprised of implant delivery system 30, 40 with
modifications to the distal balloon containing portion of implant
delivery system 30, 40. Proximal region of system 50 includes
catheter shaft 35, 45 having balloon inflation lumen 51a and
guidewire lumen 55a, inflation hub 33, 43 (not shown) and either
guidewire lumen exit skive 39 (not shown) in catheter shaft 35 or
manifold 47 (not shown) attached to catheter shaft 45 as described
above for systems 30, 40. Distal region of system 50 includes
catheter shaft 35, 45, balloon 51, stent 52, band 56a and adhesive
54. Balloon 51 is sealingly attached to catheter shaft 35, 45 at
proximal and distal bonds 51p, 51d and may be comprised of
compliant, semi compliant, non-compliant, or low pressure balloon
materials and may be comprised of biaxially oriented nylon,
polyester, Pebax, polyolefin, or other materials. In some
embodiments balloon 51 includes highly elastic materials such as
polyurethane elastomers.
[0041] Stent 52 may be comprised of stent 10, stent 20, or any
stent to which adhesive 54 can bond. For example, stent 54
configurations suitable for the invention include but are not
limited to cellular stents, fracturable stents, coil stents,
covered stents, stent grafts, mesh covered stents, tapered stents,
flared stents, braided stents, bifurcation stents, and other stents
as are known in the art. Long stents are especially suited to the
invention. Implant delivery systems 50 for stents having lengths of
from 20 to 400 mm are contemplated. In one embodiment, a stent
delivery system 50 can deliver and deploy a 30 mm stent. In other
embodiments, a stent delivery system 50 can deliver and deploy a 40
mm, 60 mm, 80 mm, 100 mm, 120 mm, 150 mm, 180 mm, 200 mm, 250 mm,
300 mm or 350 mm stent.
[0042] Band 56a is attached to catheter shaft 35, 45 by friction
fit and may be comprised of materials such as metal, Elgiloy,
platinum, platinum alloy, nickel-titanium alloy, engineering
polymer, liquid crystal polymer, polyester, nylon, or other
materials. Edges of band are rounded so as to not promote balloon
burst upon balloon inflation. Band 56a sandwiches balloon 51
between band and catheter shaft. Band is configured to allow
inflation of the portion of balloon 51 that does not underlie band
56a. In one embodiment band 56a takes the form of a coiled ribbon.
In another embodiment, outer surface of catheter 35, 45 has a
groove therealong to receive band 56a. Adhesive 54 attaches stent
52 to band 56a and may be comprised of biodegradable or dissolvable
materials such as poly lactic acid (PLA), poly glycolic acid (PGA),
or poly lactic glycolic acid (PLGA), or may be comprised of EVA,
polyurethane, nylon, or other materials. In some embodiments
adhesive extends into openings through wall thickness of stent
52.
[0043] In an alternate embodiment (FIGS. 5B and 5C), band 56b
includes one or more patches or islands of material having
circular, oval, irregular, or other shape and is further comprised
of one or more of the materials used to construct band 56a. Band
56b is bonded to balloon 51, and balloon 51 is locally bonded to
catheter shaft 35, 45 in the region underlying band 56b by means of
heat, adhesive, or other means. Local bonds of balloon 51 to
catheter shaft 35, 45 are arranged in a pattern that allows flow to
inflate unbonded portion of balloon. In yet another embodiment
(FIG. 5D), balloon is locally bonded to catheter shaft 35, 45 by
means of heat, adhesive, or other means over a patch or island
having circular, oval, irregular, or other shape and band 56c
includes the bonded region or patch or island. Local bonds of
balloon 51 to catheter shaft 35, 45 are arranged in a pattern that
allows flow to inflate unbonded portion of balloon. Adhesive 54
attaches stent 52 to band 56b, 56c and may be comprised of
biodegradable or dissolvable materials such as poly lactic acid
(PLA), poly glycolic acid (PGA), or poly lactic glycolic acid
(PLGA), or may be comprised of EVA, polyurethane, nylon, or other
materials. In some embodiments adhesive extends into openings
through wall thickness of stent 52.
[0044] An exemplary method of using a stent 52 with implant
delivery system 50 is now described. A guidewire is advanced into a
patient's femoral artery using known techniques, through a
patient's vessel and past a treatment site. Stent 52 (for example
stent 10, 20, or other stent) is loaded onto stent delivery system
50 and introduced over the guidewire into the patient's vessel. The
stent and stent delivery system combination is advanced over the
guidewire and through the patients vessel until the stent is
located at a treatment site, for example within a stenosis in a
popliteal artery. Stent 52 is deployed by inflating balloon 51
thereby fracturing adhesive 54 attachments between band(s) 56a,
56b, 56c and stent 52, causing or allowing stent to expand.
Catheter shaft 35, 45 is then withdrawn through the patient's
vessel and out of the patient's body. In the case of biodegradable
or dissolvable adhesive 54, any of adhesive that is pinned under
stent 52, or which embolizes, dissolves or degrades over time.
Stent 52 does not change length on deployment because the stent is
immobilized on catheter shaft 35 during delivery to the treatment
site and because there is no sheath to draw past the stent during
deployment.
[0045] FIGS. 6A, 6B, 8A, 8B, 8C and 8D illustrate RX delivery
system 60 comprised of implant delivery catheter 66 having distal
region 80 and stent 82. Implant delivery catheter 66 includes
catheter shaft 65, guidewire lumen 65a, proximal guidewire exit
skive 69, proximal handle 68, sheath 84 and distal manifold 67.
Proximal handle 68 is sealingly attached to catheter shaft 65 and
may be comprised of polycarbonate. Catheter shaft 65 is relatively
flexible, may be comprised of a polymeric material such as nylon or
PEBAX, and may range in length from 60 cm to 300 cm. Catheter
outside diameter may range from about 2 Fr to about 10 Fr.
Guidewire lumen 65a diameter may be large enough to allow passage
of guidewires ranging in diameter from 0.009'' to 0.038''. Distal
manifold 67 is sealingly attached to sheath 84 and may be comprised
of polycarbonate. Sheath 84 may be comprised of braid-reinforced
polyester, non-reinforced polymers such as nylon or polyester, or
other materials, and adapted to resist kinking and to transmit
axial forces along its length. Sheath 84 may be constructed so as
to have varying degrees of flexibility along its length. In one
embodiment (FIG. 6C) sheath 84 includes seal 84a, weep holes 84b,
or both. Seal prevents liquids and body fluids from contacting
stent 82 when sheath is fully advanced to cover stent 82, and may
be constructed of elastomeric materials such as low durometer
PEBAX, polyurethane, or other materials. Weep holes 84b allow
annular space between sheath 84 and catheter shaft 65 to be purged
of air. Stent 82 may be comprised of stent 10, 20, or other stents.
In some embodiments, coating 14 or shell 24 is substantially
shielded from dissolution or biodegradation causing media due to
barrier properties of sheath in combination with sheath seal.
[0046] Optionally, implant delivery catheter 66 is further
comprised of balloon 81 (FIG. 8D), balloon inflation lumen within
catheter 65 (not shown), and balloon inflation hub 63. Hub 63 is
sealingly attached to proximal handle 88, is adapted to reversibly
connect to other medical devices (for example by means of a luer
fitting) and may be comprised of polycarbonate. Balloon 81 is
sealingly attached at both proximal and distal ends to catheter
shaft 65 and may be comprised of biaxially oriented nylon,
polyester, Pebax, polyolefin, or other materials. In one
embodiment, balloon 81 is constructed such that the coefficient of
friction of the balloon in contact with stent 82 is greater than
the coefficient of friction of sheath 84 in contact with stent
82.
[0047] FIGS. 7, 8A, 8B, 8C and 8D illustrate OTW delivery system 70
comprised of implant delivery catheter 76 having distal region 80
and stent 82. Implant delivery catheter 76 includes catheter shaft
75, guidewire lumen (not shown), proximal guidewire exit port 79,
proximal handle 78, sheath 84 and distal manifold 77a. Sheath 84
may optionally be comprised of seal 84a, weep holes 84b, or both
and distal manifold 77a includes infusion tube with stopcock 77b.
Catheter shaft 75, guidewire lumen, proximal handle 78 and distal
manifold have substantially the same construction, dimensions, and
function as catheter shaft 65, guidewire lumen 65a, proximal handle
68 and distal manifold 67 described above in conjunction with FIGS.
6A to 6D. Stent 82 may be comprised of stent 10, 20, or other
stents. In some embodiments, coating 14 or shell 24 is
substantially shielded from dissolution or biodegradation causing
media due to barrier properties of sheath in combination with
sheath seal.
[0048] Optionally, implant delivery catheter 76 is further
comprised of balloon 81 (FIG. 8D), balloon inflation lumen within
catheter 75 (not shown), and balloon inflation hub 73. Hub 73 is
sealingly attached to proximal guidewire exit port 79, is adapted
to reversibly connect to other medical devices (for example by
means of a luer fitting) and may be comprised of polycarbonate.
Balloon 81 is sealingly attached at both proximal and distal ends
to catheter shaft 75 and may be comprised of biaxially oriented
nylon, polyester, Pebax, polyolefin, or other materials.
[0049] An exemplary method of using implant delivery system 60, 70
with stent 82 is now described with the assistance of FIGS. 8A to
8C. A guidewire is advanced into a patient's femoral artery using
known techniques, through a patient's vessel and past a treatment
site. Stent 82 (for example stent 10, 20) is loaded onto stent
delivery system 60, 70 (FIG. 8A) and introduced over the guidewire
into the patient's vessel. The stent and stent delivery system
combination is advanced over the guidewire and through the patients
vessel until the stent is located at a treatment site, for example
within a stenosis in an iliac artery. Stent 82 is deployed by
sliding proximal handle 68, 78 and distal manifold 67, 77a closer
together, thereby causing sheath 84 to withdraw proximally and
uncover stent 82 (FIG. 8B). Withdrawal of sheath from stent 10, 20
allows blood and/or media to contact coating or shell thereby
releasing stent restraint after dissolution or biodegradation of
coating or shell, allowing stent to self-expand (FIG. 8C). Catheter
66, 76 is then withdrawn through the patient's vessel and out of
the patient's body. Because the coating or shell restrains the
stent from expanding or changing length sheath withdrawal force is
reduced and the stent does not change length on deployment.
[0050] In some methods, sheath 84 is partially withdrawn from stent
82 so as to allow uncovered portion of stent to expand into contact
with the vessel wall, thereby providing frictional localization of
the expanded portion of the stent against the vessel wall.
[0051] In some embodiments, before dissolution or biodegradation of
coating or shell an operator can advance the sheath distally so as
to recapture the stent. This is possible because the coating or
shell provides a smooth covering over the structural portion of the
stent such that the distal end of the sheath will not become
mechanically entangled with the structural portion. Recapture of a
stent is desirable when the operator wishes to change the eventual
deployed position of the stent or for other reasons. In other
embodiments, sheath seal 84a prevents blood and/or media to contact
stent 82 during stent delivery in the patient, thereby preventing
expansion of stent 82 secondary to premature dissolution or
biodegradation of coating 14 or shell 24. In still other
embodiments, prior to introduction into a patient delivery system
60, 70 is flushed with fluid to purge air by connecting a syringe
filled with flushing solution (e.g. saline) to distal manifold 67,
77a and forcing flushing solution through sheath 84 and out weep
holes 84b, thereby preventing flushing fluid from contacting stent
82 and potentially causing premature dissolution or biodegradation
of coating 14 or shell 24.
[0052] In methods of using embodiments of implant delivery system
60, 70 where balloon 81 is incorporated into the system, balloon 81
is inflated after withdrawal of sheath 84 (FIG. 8D) by connecting
inflation device (not shown) to hub 63, 73 and pressurizing balloon
inflation lumen with fluid or gas thereby causing stent 82 to
expand after fracture or compromise of coating or shell. In some
embodiments stent 82 is fully expanded into contact with vessel
wall by expansion of balloon. Because the coating or shell
restrains the stent from expanding or changing length and because
the stent is expanded by balloon, sheath withdrawal force is
reduced and the stent does not change length on deployment.
[0053] An alternate exemplary method of using embodiments of
implant delivery system 60, 70 where balloon 81 is incorporated
into the system with stent 82 is now described with the assistance
of FIGS. 8A to 8D. A guidewire is advanced into a patient's femoral
artery using known techniques, through a patient's vessel and past
a treatment site. Stent 82 (for example any stent that self expands
when not restrained by another device or component) is loaded onto
stent delivery system 60, 70 (FIG. 8A) and introduced over the
guidewire into the patient's vessel. The stent and stent delivery
system combination is advanced over the guidewire and through the
patients vessel until the stent is located at a treatment site, for
example within a stenosis in a carotid artery. Balloon 81 is
inflated prior to withdrawal of sheath 84 (FIG. 8A, balloon not
shown) by connecting inflation device (not shown) to hub 63, 73 and
pressurizing balloon inflation lumen with fluid or gas until
sliding friction of stent 82 against balloon 81 exceeds sliding
friction of stent 82 against sheath 84. Stent 82 is deployed by
sliding proximal handle 68, 78 and distal manifold 67, 77a closer
together, thereby causing sheath 84 to withdraw proximally and
uncover stent 82 (FIG. 8D). Catheter 66, 76 is then withdrawn
through the patient's vessel and out of the patient's body. Because
the inflated balloon restrains the stent from changing length (for
example buckling, stretching, kinking, or "bunching up") in the
sheath, sheath withdrawal force is reduced and the stent does not
change length on deployment.
[0054] While the various examples of the present invention have
related to stents and stent delivery systems, the scope of the
present invention is not so limited. For example, while
particularly suited for stent delivery systems, it will be
appreciated that the various aspects of the present invention are
also applicable to systems for delivering other types of expandable
implants. By way of non-limiting example, other types of expanding
implants include anastomosis devices, blood filters, grafts, vena
cava filters, percutaneous valves, aneurism treatment devices, or
other devices.
[0055] It has been shown how certain objects of the invention have
been attained in a preferred manner. Modifications and equivalents
of the disclosed concepts are intended to be included within the
scope of the claims. Alternate materials for many of the delivery
system components are generally well known in the art can be
substituted for any of the non-limiting examples listed above
provided the functional requirements of the component are met.
Further, while choices for materials and configurations may have
been described above with respect to certain embodiments, one of
ordinary skill in the art will understand that the materials and
configurations described are applicable across the embodiments.
* * * * *