U.S. patent application number 12/337069 was filed with the patent office on 2009-04-23 for stent delivery catheter.
This patent application is currently assigned to BOSTON SCIENTIFIC SCIMED, INC.. Invention is credited to William S. Henry, John E. Ortiz.
Application Number | 20090105802 12/337069 |
Document ID | / |
Family ID | 34795196 |
Filed Date | 2009-04-23 |
United States Patent
Application |
20090105802 |
Kind Code |
A1 |
Henry; William S. ; et
al. |
April 23, 2009 |
STENT DELIVERY CATHETER
Abstract
A self-expanding stent delivery assembly includes a shaft having
a proximal end, a distal end, a distal region, a lumen, and a
longitudinal axis. A retractable sheath having an outer surface, a
proximal end and a distal end is co-axially disposed around the
shaft distal region. A stent is disposed co-axially between the
shaft and the retractable sheath. A tubular tapered tip is affixed
to the retractable sheath distal end. The tubular tapered tip has
an elongate region predisposed to fracturing. Methods of delivering
a self-expanding stent are also described.
Inventors: |
Henry; William S.; (San
Francisco, CA) ; Ortiz; John E.; (East Palo Alto,
CA) |
Correspondence
Address: |
CROMPTON, SEAGER & TUFTE, LLC
1221 NICOLLET AVENUE, SUITE 800
MINNEAPOLIS
MN
55403-2420
US
|
Assignee: |
BOSTON SCIENTIFIC SCIMED,
INC.
Maple Grove
MN
|
Family ID: |
34795196 |
Appl. No.: |
12/337069 |
Filed: |
December 17, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10764054 |
Jan 23, 2004 |
7468070 |
|
|
12337069 |
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Current U.S.
Class: |
623/1.11 ;
623/1.15; 623/1.2; 623/1.23 |
Current CPC
Class: |
A61F 2/95 20130101; A61F
2/97 20130101; A61F 2/966 20130101 |
Class at
Publication: |
623/1.11 ;
623/1.15; 623/1.23; 623/1.2 |
International
Class: |
A61F 2/06 20060101
A61F002/06 |
Claims
1. A stent delivery assembly comprising: a shaft having a proximal
region and a distal region; a self-expanding stent disposed about
at least a portion of the distal region of the shaft; a sheath
having a proximal end and a distal end, the sheath disposed around
at least the distal region of the shaft and the self-expanding
stent, wherein the sheath is configured to be retracted from the
self-expanding stent to deploy the self-expanding stent; and a
tubular tapered tip coupled to the distal end of the sheath, the
tubular tapered tip having a region predisposed to fracturing.
2. The stent delivery assembly of claim 1, wherein the region
predisposed to fracturing is configured to fracture when the sheath
is retracted from the stent.
3. The stent delivery assembly of claim 1, further comprising a
stop member coupled to the shaft and positioned proximally of the
self-expanding stent.
4. The stent delivery assembly of claim 1, wherein the tubular
tapered tip has a plurality of elongate regions predisposed to
fracturing, wherein each elongate region predisposed to fracturing
are co-planar.
5. The stent delivery assembly of claim 1, wherein the elongate
region predisposed to fracturing includes a line of
perforations.
6. The stent delivery assembly of claim 1, wherein the tubular
tapered tip has a first thickness and the elongate region
predisposed to fracturing has a second thickness that is less than
the first thickness.
7. The stent delivery assembly of claim 1, wherein the tubular
tapered tip is formed of a first material having a first tensile
strength and the elongate region predisposed to fracturing is
formed of a second material having a second tensile strength that
is less than the first tensile strength.
8. The stent delivery assembly of claim 1, further comprising a
guidewire disposed within the shaft lumen.
9. The stent delivery assembly of claim 8, wherein the tubular
tapered tip has a distal end defining a tip opening, the tip
opening sized and configured to surround the guidewire.
10. A stent delivery assembly comprising: a shaft having a proximal
region and a distal region; a stent disposed about at least a
portion of the distal region of the shaft; a sheath having a
proximal end and a distal end, the sheath moveable between at least
a first position and a second position, when in the first position,
the sheath is disposed around the distal region of the shaft and
the self-expanding stent, when the sheath is in the second
position, the sheath is disposed around the distal region of the
shaft with the distal end of the shaft being proximal of a proximal
end of the stent, wherein the movement of the sheath between the
first position and the second position deploys the stent; and a
tubular tapered tip coupled to the distal end of the sheath, the
tubular tapered tip having a region predisposed to fracturing,
wherein moving the sheath from the first position to the second
position causes the region predisposed to fracturing to
fracture.
11. The stent delivery assembly of claim 10, wherein the stent is a
self-expanding stent.
12. The stent delivery assembly of claim 10, further comprising a
stop member coupled to the shaft and positioned proximally of the
stent.
13. The stent delivery assembly of claim 10, wherein the elongate
region predisposed to fracturing includes a line of
perforations.
14. The stent delivery assembly of claim 10, wherein the tubular
tapered tip has a first thickness and the elongate region
predisposed to fracturing has a second thickness that is less than
the first thickness.
15. The stent delivery assembly of claim 10, wherein the tubular
tapered tip is formed of a first material having a first tensile
strength and the elongate region predisposed to fracturing is
formed of a second material having a second tensile strength that
is less than the first tensile strength.
16. The stent delivery assembly of claim 10, further comprising a
guidewire disposed within the shaft lumen.
17. The stent delivery assembly of claim 16, wherein the tubular
tapered tip has a distal end defining a tip opening, the tip
opening sized and configured to surround the guidewire.
18. A method of delivering a self-expanding stent to a target site
in a vessel, the method comprising: positioning a stent delivery
device at the target site in the vessel, the stent delivery device
comprising: a self-expanding stent disposed about at least a
portion of the distal region of the shaft; a sheath having a
proximal end and a distal end, the sheath disposed around at least
the distal region of the shaft and the self-expanding stent,
wherein the sheath is configured to be retracted from the
self-expanding stent to deploy the self-expanding stent; and a
tubular tapered tip coupled to the distal end of the sheath, the
tubular tapered tip having a region predisposed to fracturing; and
retracting the sheath from the stent to deploy the stent at the
target site, wherein the retracting causes the region predisposed
to fracturing to fracture.
19. The method of claim 18, wherein the self-expanding stent
expands when the sheath is retracted from the self-expanding
stent.
20. The method of claim 18, further comprising placing a guidewire
across the target site prior to placing the stent delivery device
at the target site, wherein the tubular tapered tip has a distal
end defining a tip opening, the tip opening sized and configured to
pass the guidewire therethrough.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/764,054, filed Jan. 23, 2004, the entire
disclosure of which is incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention is related generally to medical
devices. More specifically, the present invention is related to
catheters. The present invention includes stent delivery catheter
apparatus with a tapered tip that is fracturable during deployment
of a self-expanding stent that has been loaded onto the
catheter.
BACKGROUND OF THE INVENTION
[0003] Atherosclerotic disease is a leading cause of death in the
industrialized world, particularly in the United States. Many heart
attacks and strokes are caused in part by a narrowed, stenosed
blood vessel. A medical procedure commonly used to deal with vessel
stenosis is angioplasty. Angioplasty, in particular Percutaneous
Transluminal Angioplasty (PTA), includes inserting a balloon
catheter into the femoral artery near the groin, and advancing the
catheter to the stenosis. The balloon can then be inflated to widen
or dilate the narrowed region. The balloon catheter can then be
withdrawn. In some cases, the widened vessel rebounds or re-closes,
narrowing the vessel over a period of time.
[0004] Stents have come into increasing use to prevent the widened
vessel regions from narrowing after angioplasty. A stent, typically
having a tubular shape, can be put in place in the widened vessel
region to hold the vessel walls apart and the lumen open in the
event the conditions would otherwise result in re-stenosis. One
class of stents requires that the stent be forcibly outwardly
expanded to put the stent into position against the vessel walls.
Another class of stents, self-expanding stents, can be delivered to
a site in a compressed or constrained configuration and released in
the vessel region to be supported. The self-expanding stent then
expands in place to a configuration having a wide lumen, typically
pressing firmly against the vessel walls where released. The stent
is commonly placed at a recently dilated, stenosed vessel
region.
[0005] Self-expanding stents can be delivered to a target site
mounted over an inner tube or shaft and constrained within the
distal end of an enclosing retractable tube or sleeve. The
self-expanding stent can be freed from the restraint of the outer
sheath by either distally pushing the inner shaft against the stent
or proximally pulling the retractable outer sheath from over the
stent. Once free of the outer restraint, the self-expanding stent
can expand to force itself against the vessel inner walls.
Self-expanding stents are often elastically biased to assume an
original larger shape after being temporarily compressed into a
smaller size to more easily be transported through blood vessels to
the target site. There is an ongoing need for improvements in
catheters that deliver self-expanding stents.
SUMMARY OF THE INVENTION
[0006] Generally, the present invention relates to a stent delivery
device having a tapered tip that is fracturable during deployment
or by deploying a self-expanding stent from the stent delivery
device.
[0007] In one embodiment, a self-expanding stent delivery assembly
includes a shaft having a proximal end, a distal end, a distal
region, a lumen, and a longitudinal axis. A retractable sheath
having an outer surface, a proximal end and a distal end is
co-axially disposed around the shaft distal region. A stent is
disposed co-axially between the shaft and the retractable sheath. A
tubular tapered tip is bonded to the retractable sheath distal end.
The tubular tapered tip has an elongate region predisposed to
fracturing.
[0008] In another embodiment, a method of delivering a
self-expanding stent includes placing a stent delivery device at a
target site. The stent delivery device includes a shaft having a
proximal end, a distal end, a distal region, a lumen, and a
longitudinal axis; a retractable sheath having a proximal end and a
distal end co-axially disposed around the shaft distal region; a
stent disposed co-axially between the shaft and the retractable
sheath; and a tubular tapered tip bonded to the retractable sheath
distal end, the tubular tapered tip having an elongate region
predisposed to fracturing. The stent is deployed at the target site
by retracting the retractable sheath or advancing the stent and
fracturing the elongate region predisposed to fracturing. The stent
delivery device is then removed from the target site.
[0009] The above summary of the present invention is not intended
to describe each disclosed embodiment or every implementation of
the present invention. The Figures and Detailed Description which
follow more particularly exemplify these embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention may be more completely understood in
consideration of the following detailed description of various
embodiments of the invention in connection with the accompanying
drawings, in which:
[0011] FIG. 1 is a partial longitudinal cross-sectional view of a
stent delivery device;
[0012] FIG. 2 is a cross-sectional view of the stent delivery
device of FIG. 1 taken along line 2-2;
[0013] FIG. 3 is a perspective view of a tapered tip;
[0014] FIG. 4 is a perspective view of the tapered tip of FIG. 3
while partially deploying a stent;
[0015] FIG. 5 is a perspective view of another embodiment of a
tapered tip; and
[0016] FIG. 6 is a perspective view of the tapered tip of FIG. 5
while partially deploying a stent.
[0017] While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit the
invention to the particular embodiments described. On the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0018] The stent delivery device and method for using the stent
delivery device of the present invention are believed to be
applicable to a variety of applications where delivery of stents is
desired, for example, atherosclerotic stent delivery. While the
present invention is not so limited, an appreciation of various
aspects of the invention will be gained through a discussion of the
examples provided below.
[0019] The recitation of numerical ranges by endpoints includes all
numbers subsumed within that range (e.g., 1 to 5 includes 1, 1.5,
2, 2.75, 3, 3.80, 4, and 5).
[0020] As used in this specification and the appended claims, the
singular forms "a", "an", and "the" include plural referents unless
the content clearly dictates otherwise. Thus, for example,
reference to "an elongate region" includes two or more elongate
regions. As used in this specification and the appended claims, the
term "or" is generally employed in its sense including "and/or"
unless the content clearly dictates otherwise.
[0021] Also, while the tubular members illustrated in the Figures
have generally circular cross sections, this is not a necessary
part of the present invention, and the tubular members are merely
shown as such for purposes of simplicity in illustration.
[0022] FIG. 1 illustrates a stent delivery device or catheter 30.
Catheter assembly 30 includes an inner tube 32 having a lumen 33
therethrough (as shown in FIG. 2), a distal region 40 and a distal
end 42. Inner tube 32 is preferably formed of a metal, polymeric
material, or polymeric/metal composite material suitable for
delivering a stent through tortuous vessel passages and in one
embodiment, is suitable for receiving a guidewire therethrough. One
useful material can include a braided polyamide tubing. In an
illustrative embodiment, the catheter assembly 30 can be guided to
the target site via a guidewire 80. In the illustrative embodiment,
the guidewire 80 can be within the inner tube 32 lumen 33. The
guide wire can be any operable diameter such as, for example, 0.01
to 0.04 inch or 0.014 to 0.035 inch, however a guide wire is not
required in all embodiments.
[0023] In an illustrative embodiment, a retractable sheath 34
having a distal region or end 44 is slidably disposed over inner
tube 32, having an annular space 66 sufficient in size to receive a
compressed stent between inner tube 32 and retractable sheath 34.
Alternatively or in addition, the retractable sheath 34 can remain
static, and a stent or inner tube 32 can be advancable relative to
the retractable sheath 34. Retractable sheath 34 can be formed of a
metal, polymeric material, or polymeric/metal composite material
preferably sufficiently lubricious to ease in advancing catheter
assembly 30 through increasingly smaller blood vessels. Sheath 34
can be formed from a variety of materials such as, for example,
high density polyethylene, nylon, reinforced nylons, or
polyurethanes. Sheath 34 can have an inner layer 31 including a
lubricious material such as, for example,
polytetrafluoroethylene.
[0024] In an illustrative embodiment, a stop 35 is affixed to the
inner tube 32 proximal of its distal end 42, about the length of a
stent 50 and near the distal end of the catheter 30. The stop 35
functions to hold the stent 50 axially during deployment of the
stent 50 relative to the outer tube 34.
[0025] A distally positioned tapered tip 36 is disposed distal to
or adjacent to the inner tube distal region 40 and is affixed to or
formed integral with retractable sheath 34. In one embodiment,
tapered tip 36 can be formed of a shrinkable film material, for
example, a heat-shrinkable material such as polyolefin copolymer,
nylon, or polytetrafluoroethylene. In another embodiment, tapered
tip 36 can be formed of the same or similar material to the
material forming the retractable sheath 34. In another embodiment,
the tapered tip 36 can be formed from the same layer of material
forming at least a portion of the retractable sheath 34. If
necessary, the tapered tip 36 can be secured to retractable sheath
34 using a variety of methods such as, for example, molding,
extrusion, heat bonding, adhesives, laser bonding, or solvent
welding, using methods well known to those skilled in the art. Any
type of connection means may be used to affix the tapered tip 36 to
the retractable sheath 34. This connection means can include, for
example, a lap joint, butt joint or integral molding. Alternatively
or in addition, a mechanical connection such as threads or friction
fit could be utilized. In an illustrative embodiment, the tapered
tip 36 can include a waist portion 64 and a free portion 60. In the
illustrative embodiment shown, the tapered tip 36 is formed
integrally with retractable sheath 34 and the outer surface of the
tapered tip 36 is continuous with the outer surface of the
retractable sleeve 34, thus the connection is smooth and
substantially free of transitions.
[0026] Tapered tip 36 is illustrated having an open distal end 70.
However, the tapered tip 36 can have a closed distal end 70. The
open distal end 70 can be sized and configured to slidably engage
or pass the guide wire 80. However, a guide wire 80 is not required
in all embodiments. In the illustrative embodiment, the waist
portion 64 can be disposed to and affixed to the distal end 44 of
the retractable sheath 34. The free portion 60 can extend distally
beyond the distal end 44 of the retractable sheath 34.
[0027] The tapered tip 36 can aid in tracking stent delivery device
30 through vessel passages and turns. In an illustrative
embodiment, the tapered tip 36 is conically tapered. However, the
tapered tip 36 can have an arcuate taper or any arrangement of
constant diameters and tapers, as desired.
[0028] As depicted in FIG. 3, the tubular tip 36 has at least one
elongate region predisposed to fracturing 90. The tubular tip 36
can have 2, 3, 4, 5, 6, 7, 8, 9, 10 or more elongate regions
predisposed to fracturing 90. The elongate region predisposed to
fracturing 90 fractures the tapered tip to expand the open distal
end 70 and allows the stent 50 to pass through the fractured
tapered tip 36 open distal end 70 generally unimpeded. In an
illustrative embodiment, the elongate region predisposed to
fracturing 90 can be co-planar with a longitudinal axis running
along the length of the stent delivery device 30. The elongate
region predisposed to fracturing 90 can be formed on the tapered
tip 36 before the tapered tip 36 is affixed to the retractable
sheath 34, or formed during the process of affixing the tapered tip
36 to the retractable sheath 34 or integrally forming the tapered
tip 36 from the layer of material forming at least a portion of the
retractable sheath 34, or after affixing/integrally forming the
tapered tip 36 with the retractable sheath 34.
[0029] In an illustrative embodiment, the elongate region
predisposed to fracturing 90 can be a line of perforations that
extend through a portion of or through the entire tubular tip 36
wall thickness. The elongate region predisposed to fracturing 90
can be a score line that extends through a portion of the tubular
tip 36 wall thickness where the wall thickness along the score line
90 is less than the thickness along the remaining tubular tip 36
wall. Alternatively or in addition, the elongate region predisposed
to fracturing 90 can be material having a tensile strength that is
less than the tensile strength of the remaining tubular tip 36.
[0030] FIG. 2 is a cross-sectional view of the stent delivery
device of FIG. 1 taken along line 2-2. An inner lumen 33 is
coaxially disposed about a guidewire 80. A self-expanding stent 50
can be placed into annular space 66 between retractable sheath 34
and inner tube 32.
[0031] In an illustrative embodiment, the stent 50 can be placed
over the inner tube 32 by sliding the stent 50 proximally over the
inner tube distal end 42. Stent 50 can be compressed using a
suitable tool or jig, to decrease the outer diameter of the stent
50 to a size compatible with the annular space 66. With the stent
50 compressed, the stent 50 can be axially and proximally slid over
inner tube 32 and within sleeve distal region 44, to reside in
annular space 66. With the stent 50 constrained by retractable
sleeve 34, any restraining tool or jig can be removed from the
catheter. With stent 50 in position, tubular tip 36 can be affixed
to retractable sheath 34 distal end 44.
[0032] In another illustrative embodiment, a compressed stent 50
can be placed onto the inner tube 32 and loaded into the catheter
30 from a proximal end of the catheter 30. The inner tube 32 and
compressed stent 50 can be moved toward the sleeve distal region
44. The tubular tip 36 can be attached to the retractable sheath 34
prior to loading the compressed stent 50 into the catheter 30.
[0033] In an illustrative embodiment, the retractable sheath 34 can
be any material as described above such as, for example, a clear
medical grade PTFE (polytetrafluoroethylene) extrusion which covers
the distal 2-20 cm (depending on stent length) of the stent
delivery device 30. However, the retractable sheath 34 could be
made of any suitable material as described above. A specific
alternative embodiment could utilize a fluoropolymer material which
is transparent to visible light to enable the operator to directly
view deployment in an endoscopic delivery procedure. Such materials
are well known in the art. In an illustrative embodiment,
self-expanding nitinol stents of from 1-15 mm or 6-14 mm in
diameter and ranging from 1-100 mm or 5-50 mm in length can be
accommodated. It should be understood that any type of
self-expanding stent could be employed. In an illustrative
embodiment, the retractable sheath 34 can be connected to a
proximal retraction handle (not shown) by a stainless steel
pull-wire. In this embodiment, the proximal end of retractable
sheath 34 slidably seals to elongate shaft 20, permitting it to
slide proximally along elongate shaft when retracted by pull-wire.
In another illustrative embodiment, the stent delivery system can
include a rapid exchange guide wire system.
[0034] The stent 50 can be compressed at low temperature for
loading into delivery system 30 and held in its reduced delivery
configuration by retractable sheath 34. Upon deployment in vivo at
body temperature, the original stent shape can be restored as the
nitinol stent self-expands, exerting radial force on the
constricted portion of the body lumen to re-establish patency. A
stent delivery catheter showing the retraction handle is described
in U.S. Pat. No. 6,391,051, which is incorporated by reference
herein.
[0035] FIG. 3 is a perspective view of a tapered tip 36 prior to
deploying a stent 50. As described above, a tubular tip 36 can be
affixed to the distal end 44 of the retractable sheath 34. In the
illustrative embodiment, the tubular tip 36 includes a waist
portion 64 and a tapered portion 60. The waist portion 64 is shown
integrally bonded to or integrally formed with the distal region or
end 44 of the retractable sheath 34 providing a continuous and/or
smooth outer surface across the tubular tip 36 and retractable
sheath 34. In the illustrative embodiment, the tubular tip 36 has
an open distal end 70 with an inner diameter that is less than the
inner diameter of the waist portion 64 and is sized and configured
to engage a guidewire 80, but this is not required in all
embodiments. The tubular tip 36 has at least one elongate region 90
predisposed to fracturing as described above.
[0036] FIG. 4 is a perspective view of the tapered tip of FIG. 3
while partially deploying a stent 50. As the retractable sheath 34
is moved toward the elongate shaft 20 in the direction D, the
elongate region predisposed to fracturing 90 fractures and the
tapered tip 36 expands to allow the stent 50 to expand away from
the inner tube 32 and onto the target site. The stent 50 fractures
the tapered tip 36 as the stent 50 passes through the tapered tip
36 substantially unencumbered.
[0037] FIG. 5 is a perspective view of another tapered tip 136
prior to deploying a stent 150. As described above, a tubular tip
136 can be affixed to the distal region or end 144 of the
retractable sheath 134. The tubular tip 136 includes a waist
portion 164 and a tapered free portion 160. The waist portion 164
can be bonded to the distal end 144 of the retractable sheath 134.
The tubular tip 136 has a closed distal end 171 with an inner
diameter that is less than the inner diameter of the waist portion
164. The tubular tip 136 has at least two elongate regions 190
predisposed to fracturing as described above.
[0038] FIG. 6 is a perspective view of the tapered tip of FIG. 5
while partially deploying a stent 150. As the retractable sheath
134 is moved toward the elongate shaft in the direction D, the
elongate regions predisposed to fracturing 190, fractures and the
tapered tip 136 expands to allow the stent 150 to expand away from
the inner tube 132 and onto the target site. The stent 150
fractures the tapered tip 136 as the stent 150 passes through the
tapered tip 136 substantially unencumbered.
[0039] Alternatively in some embodiments, the stent 150 may be
deployed by advancing the inner tube 132 or stent 150 through the
tapered tip 136 in an opposite direction to direction D. Similarly
to above, the elongate regions predisposed to fracturing 190,
fractures and the tapered tip 136 expands to allow the stent 150 to
expand away from the inner tube 132 and onto the target site. The
stent 150 fractures the tapered tip 136 as the stent 150 passes
through the tapered tip 136 substantially unencumbered.
[0040] Numerous advantages of the invention covered by this
document have been set forth in the foregoing description. It will
be understood, however, that this disclosure is, in many respects,
only illustrative. Changes may be made in details, particularly in
matters of shape, size, and arrangement of parts without exceeding
the scope of the invention. The invention's scope is, of course,
defined in the language in which the appended claims are
expressed.
* * * * *