U.S. patent application number 09/815567 was filed with the patent office on 2001-10-25 for introducer sheath.
This patent application is currently assigned to Cook Incorporated. Invention is credited to Parker, Fred T..
Application Number | 20010034514 09/815567 |
Document ID | / |
Family ID | 22706620 |
Filed Date | 2001-10-25 |
United States Patent
Application |
20010034514 |
Kind Code |
A1 |
Parker, Fred T. |
October 25, 2001 |
Introducer sheath
Abstract
Introducer sheath (10, 30, 40) having a flexible kink-resistant
distal tip portion (26, 32, 42). A multilayer sheath structure is
used, with an inner tube (12) such as PTFE having a coil (14) of
wire wound therearound. A first length of outer tubing (20) such as
of nylon is inserted over most of the coil-wound inner tube (12) in
a manner exposing a distal length of coil-wound inner tube. A
second length of outer tubing (22) with a softer durometer than
first outer tubing length (20), is inserted over the exposed
coil-wound inner tube and extends for a slight distance beyond the
end of the coil. During heat application, the outer tubing lengths
(20, 22) are melted to bond to each other and to flow between the
spacings of the coil turns to bond to the roughened outer surface
of the inner tube (12). The distal tip region corresponding to the
second tubing length is flexible and is kink-resistant due to the
coil (14).
Inventors: |
Parker, Fred T.;
(Unionville, IN) |
Correspondence
Address: |
Anton P. Ness
Patent Attorney
P.O. Box 2269
Bloomington
IN
47402-2269
US
|
Assignee: |
Cook Incorporated
925 S. Curry Pike
Bloomington
IN
47402-0489
|
Family ID: |
22706620 |
Appl. No.: |
09/815567 |
Filed: |
March 23, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60191709 |
Mar 23, 2000 |
|
|
|
Current U.S.
Class: |
604/525 ;
604/527 |
Current CPC
Class: |
A61M 25/0054 20130101;
A61M 25/0053 20130101; A61M 25/0662 20130101; A61M 25/005
20130101 |
Class at
Publication: |
604/525 ;
604/527 |
International
Class: |
A61M 025/00 |
Claims
What is claimed is:
1. An intravascular sheath comprising: an inner tube extending to a
distal end; a wire coil wound around said inner tube extending to
an end spaced proximally from said inner tube distal end; a first
outer tube disposed around said wire coil and said inner tube
therewithin to a first outer tube distal end spaced proximally from
said wire coil distal end such that a distal end portion of said
wire coil extends distally therebeyond; and at least a second outer
tube disposed around said wire coil and said inner tube therewithin
extending distally from said first outer tube distal end and
covering said distal end portion of said wire coil and extending
slightly beyond said distal end of said inner tube, said first
outer tube being of a material having a relatively hard durometer,
and said second outer tube being of a material of a substantially
softer durometer than said material of said first outer tube.
2. The intravascular sheath according to claim 1, wherein said
outer tube and said inner tube are bonded to each other and to said
wire coil and to said inner tube between windings of said wire
coil.
3. The intravascular sheath according to claim 2, wherein an
outwardly facing surface of said inner tube has been roughened to
enhance bonding thereto of said first and second outer tubes.
4. The intravascular sheath according to claim 2, wherein said
bonding is heat bonding.
5. The intravascular sheath according to claim 1, wherein a
radiopaque marker band is affixed to said wire coil distal end
within said second outer tube.
6. The intravascular sheath according to claim 1, wherein said
second outer tube is polymeric and contains radiopaque filler.
7. The intravascular sheath according to claim 6, wherein said
second outer tube contains between about 20% and 85% by weight of
radiopaque filler particles.
8. The intravascular sheath according to claim 6, wherein said
second outer tube contains about 80% by weight of radiopaque filler
particles.
9. The intravascular sheath according to claim 1, wherein said
first outer tube is substantially free of radiopaque filler.
10. The intravascular sheath according to claim 1, wherein said
second outer tube comprises a material having a durometer of at
least 5 D lower than that of the first outer tubing length.
11. The intravascular sheath according to claim 10, wherein said
first outer tube comprises a material having a durometer of about
56 D to 58 D.
12. The intravascular sheath according to claim 1, wherein said
second outer tube comprises a material having a durometer of
between about 10 D and 75 D.
13. The intravascular sheath according to claim 12, wherein said
second outer tube comprises a material having a durometer of about
39 D.
14. The intravascular sheath according to claim 1, wherein said
first and second outer tubes are distinctly different in color or
shade.
15. The intravascular sheath according to claim 1, wherein said
wire coil comprises flat wire.
16. The intravascular sheath according to claim 1, wherein a distal
tip region of the sheath is arcuate.
17. The intravascular sheath according to claim 16, wherein said
arcuate distal tip region has a length of about 1 cm or more.
18. The intravascular sheath according to claim 16, wherein said
arcuate distal tip region extends about an angle of about
90.degree..
19. The intravascular sheath according to claim 1, wherein said
wire coil extends for a length of about five millimeters beyond
said distal end of said first outer tube.
20. The intravascular sheath according to claim 1, wherein said
inner tube is unitarily formed.
21. An intravascular sheath comprising: an inner tube extending to
a distal end; a wire coil wound around said inner tube extending to
an end spaced proximally from said inner tube distal end; a first
outer tube disposed around said wire coil and said inner tube
therewithin to a first outer tube distal end spaced proximally from
said wire coil distal end such that a distal end portion of said
wire coil extends for a length of about 1 cm distally therebeyond;
and a second outer tube distally from said first outer tube distal
end and disposed around and covering said distal end portions of
said wire coil and said inner tube therewithin and extending
slightly therebeyond; said first outer tube being of a material
having a durometer of between about 50 D and 60 D, and said second
outer tube being of a material of a durometer of between about 35 D
and 45 D; said second outer tube comprises a radiopaque material;
said wire coil is of flat wire; said first and second outer tubes
are bonded to said inner tube and to said wire coil.
Description
RELATED APPLICATION INFORMATION
[0001] This application claims priority from U.S. Provisional
Patent Application Serial No. 60/191,709 filed Mar. 23, 2000.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of medical
devices and more particularly to introducer sheaths.
BACKGROUND OF THE INVENTION
[0003] Introducer sheaths are well-known for percutaneous vascular
access and typically comprise polytetrafluoroethylene or
fluorinated ethylene propylene. These sheaths are of a thin-walled
construction, but tend to kink, which is unacceptable since upon
kinking the sheath is unusable and cannot be straightened while
positioned in the body of a patient and must therefore be removed
leaving an enlarged, bleeding opening which typically cannot be
reused for the necessary percutaneous entry. Increasing the
thickness of the sheath wall only minimally improves the level of
kink resistance while enlarging the entry hole which generally is
undesirable.
[0004] One introducer sheath with improved kink resistance is
disclosed in U.S. Pat. No. 5,380,304 to Parker. The introducer
sheath comprises a coil having a plurality of turns positioned and
compression-fitted around an inner tube. An outer tube is connected
to the inner tube through the uniform spacing of the coil turns. As
a result, the compression-fitted coil reinforces the wall to
provide an extremely kink-resistant and thin-walled introducer
sheath. Preferably, the coil comprises flat wire for minimizing the
wall thickness of the sheath.
[0005] The distal ends of the inner and outer tubes extend beyond
the distal end of the coil, and the distal end of the outer tube is
tapered and extends beyond the distal end of the inner tube to
advantageously prevent the inner tube from presenting a rough edge
or surface, which may cause injury to the vessel wall. The outer
tube is said to comprise a heat-formable polyamide material such as
nylon for connecting with the rough outer surface of the inner
tube, between the coil turns. A distal tip member of nylon is then
bonded onto the distal tip of the outer tube, and is of the same
durometer, or is harder to further facilitate entry into the
percutaneous access site.
[0006] It is desired to provide a kink-resistant introducer sheath
that has a more flexible distal tip, enabling introducer sheaths to
be utilized in applications involving more tortuous paths or more
sensitive treatment sites.
SUMMARY OF THE INVENTION
[0007] The foregoing problems are solved and a technical advance is
achieved in an illustrative flexible, kink-resistant, introducer
sheath having a flexible distal tip portion. The sheath of the
present invention includes an inner tube such as of
polytetrafluoroethylene, and a flat wire coil wound therearound. A
first length of outer tubing of a conventional relatively hard
material such as of nylon, extends along most of the length of the
coil-wound inner tube. A second, short length of outer tubing is
selected to have a softer durometer than the first length of outer
tubing, and is placed over the exposed coil-wound length of the
inner tube and abutted against the end of the first length of outer
tubing. Both first and second lengths of outer tubing are melted to
flow between the spacings of the coil wire to bond to the roughened
outer surface of the inner tube and to thermally bond to each other
at the abutment location. After appropriate tapering of the distal
end of the second outer tubing length, a sheath is fabricated
having a flexible distal tip portion.
[0008] Thus, the present invention provides an introducer sheath
for use in applications such as renal and other arterial
applications involving tortuous vascular paths and that has an
atraumatic flexible kink-resistant distal tip portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Embodiments of the present invention will now be described
by way of example with reference to the accompanying drawings, in
which:
[0010] FIG. 1 is a Prior Art elevation view of an introducer sheath
assembly;
[0011] FIG. 2 is an enlarged partial cross-sectional view of the
distal tip region of the Prior Art introducer sheath of FIG. 1;
[0012] FIG. 3 is an enlarged partial cross-sectional view of the
distal tip region of the sheath of the present invention during
fabrication thereof;
[0013] FIG. 4 is a view similar to FIG. 3 after thermal bonding;
and
[0014] FIGS. 5 and 6 illustrate sheaths of the present invention
with distal tip regions that are either linear or formed to be
arcuate.
DETAILED DESCRIPTION
[0015] FIGS. 1 and 2 show an introducer sheath assembly 100 of the
prior art, as in U.S. Pat. No. 5,380,304. A dilator 102 extends
through a passageway of sheath 104 such that a tapered distal tip
106 of dilator 102 extends beyond the tapered distal end 108 of
sheath 104. Sheath 104 also includes a connector valve 110 affixed
at its proximal end 112, that includes a silicone disk (not shown)
for preventing the backflow of fluids therethrough. Connector valve
110 also includes a side arm 114 to which polyvinyl tube 116 and
Luer lock connector 118 are connected for introducing and
aspirating fluids therethrough. Tapered distal end 106 of dilator
102 facilitates accessing and dilating a vascular access site over
a well-known and commercially available wire guide (not shown). A
Luer lock connector hub 120 is attached at the proximal end of the
dilator for connection to syringes and other medical apparatus.
[0016] Depicted in FIG. 2 is a partially sectioned view of Prior
Art introducer sheath 104, with dilator 102 removed from
longitudinal sheath passageway 122. Sheath 104 comprises an outer
tube 124, an inner tube 126 of polytetrafluoroethylene (PTFE), and
a flat wire coil 128 compression fitted around inner tube 126
within outer tube 124. Outer tube 124 is joined to the roughened
outer surface 130 of inner tube 126 between the spacings of the
coil, in accordance with the disclosure of U.S. Pat. No. 5,380,304,
wherein during fabrication a sleeve of heat shrinkable tubing is
placed around the outer tube, a mandrel inserted through and beyond
inner tube 126, and heat applied until the outer tube melts to flow
between the spacings of the wire coil, being urged thereinto by
shrinking of the heat shrink sleeve, which is thereafter removed.
Pursuant to the patent, a distal tip portion 132 is thermally
bonded to a tapered distal end 134 of outer tube 124, and is of the
same durometer as outer tube 124, or harder, and has a tapered end
that forms tapered distal end 108 of sheath 104. Inner surface 136
of PTFE inner tube 126 is lubricious and slippery to facilitate
insertion and withdrawal of dilator 102 and of catheters and the
like therethrough. Proximal end 138 of sheath 104 is flared to
facilitate retention thereon of valve 110.
[0017] In the present invention illustrated in FIGS. 3 to 6, sheath
10 includes an inner tube 12 corresponding to inner tube 126 of
FIG. 2, with a roughened outer surface and preferably of PTFE, and
flat wire coil 14 wound spirally therearound. A mandrel 16 is
inserted through passageway 18 of inner tube 12, and a first length
of outer tubing 20 (or proximal outer tubing) is placed over much
of the length of the coil-wound inner tube 12, with a selected
length of the coil-wound inner tube remaining exposed. First outer
tubing length 20 may be of for example nylon having a durometer of
between about 50 D and 60 D (Shore D hardness) and may preferably
be about 56 to 58 D. However, in certain applications it may be
desired for the first outer tubing to have a hardness of up to 80
D.) A second, short length of outer tubing 22 (or distal outer
tubing) of nylon having a softer durometer than first tubing length
20, such as between about 35 D and 45 D and preferably about 39 D,
is then placed over the exposed length of coil-wound inner tube 12
and abutted against the end of first outer tubing length 20. The
exposed length of coil may be about 5 mm to 1 cm or more beyond the
distal end of the first outer tube for prevention of kinking at
least at the junction of the first and second outer tubing lengths,
and the coil may extend if desired for almost the entire length of
the second outer tubing, such as for an infusion/drainage catheter
with multiple side ports along an extended length.
[0018] Regarding the durometer of the second length of outer tubing
22, in applications such as superselective tracking catheters where
the leading end must negotiate small, tortuous vessels, the
durometer may be selected to be as low as about 10 D for being
optimally atraumatic. In other applications such as introducer
catheters for placement of stents and various interventional
devices where torque transfer and pushability are desired, the
durometer of the second tubing length may be selected to be, for
example, only about 5 D lower than that of the first length of
outer tubing 20, such as about 45 D where the first length 20 is
about 50 D.
[0019] A length of heat shrinkable sleeve 24 is placed over the
entire arrangement, and ends thereof are preheated to shrink at
ends of the assembly to hold the first and second lengths against
each other. Preferably the first and second lengths of outer tubing
20, 22 are distinctly different in color or at least shade, such
that abutment can be assured by visual inspection through
transparent heat shrinkable sleeve 24.
[0020] Upon heating to melt the outer tubing lengths 20, 22 to flow
between the turns of the coils to bond to inner tube 12 while being
compressed by the shrinking of heat shrinkable sleeve 24, a distal
tip portion 26 results that is flexible due to the softer durometer
of second outer tubing length 22, and that is kink-resistant due to
coil 14. After fabrication the heat shrunk sleeve 24 is removed. A
taper is then formed adjacent the distal tip of the sheath for a
length of about 6 mm, such as by conventional grinding. Optionally,
a hydrophilic coating is applied to the outer surface of the
sheath.
[0021] As seen in FIG. 5, one embodiment of sheath 30 the present
invention can have a distal tip region 32 that is linear in form
and that is elongate such as about 7 cm, especially suitable for
vascular applications involving tortuous paths, the elongate
flexible kink-resistant distal tip portion being atraumatic. Also
seen is a radiopaque marker band 34 positioned about one-quarter
inch from tip 36. In FIG. 6 is seen another embodiment sheath 40
having distal tip region 42 that is formed into an arcuate section
by placing the fabricated sheath under elevated temperatures while
being constrained in a template of appropriate curvature; for
example, a flexible kink-resistant distal tip portion of about 2.5
cm with such curvature is especially suitable for use in entering
the renal ostium and eases stress to the renal artery. Preferably,
such curvature extends about an angle of about 90.degree.. Where it
is desired for the sheath to have a distinct curvature, it would be
desirable for the durometer of the second outer tubing length to
have a durometer closer to that of the first outer tubing length,
such as its durometer being only about 5 D or 10 D lower than that
of the first outer tubing length.
[0022] The second outer tubing length can have a length of from
about 1 cm to about 7 cm and preferably is hydrophilic coated.
Preferably a radiopaque marker band, such as of platinum alloy or
tungsten or gold, is positioned about the distal end of the coil
prior to placement of the outer tubing lengths thereover and
thermal bonding, whereafter the marker band becomes embedded within
the outer tubing. Additionally, for certain applications it is
preferred that the second outer tubing length have a content of
radiopaque filler, such as between about 20% and 85%, and
preferably about 80%, by weight of tungsten or barium sulphate
particles or the like, while the first outer tubing length
substantially does not have a radiopaque filler content.
[0023] Additionally, it may be desired to provide at least one
intermediate outer tubing length between the first and second outer
tubing lengths, with a respective durometer between that of the
first and second tubing lengths.
[0024] The inner tube preferably comprises one continuous tube, but
it can be an arrangement formed from two or more tubes fixed in an
end-to-end relationship. The use of two or more inner tubes enables
the durometer to be reduced in a distal direction in a manner
similar to that of the outer tube arrangement which can have two or
more outer tubes. The junctions in the inner arrangement would
clearly need to be offset from those in the outer arrangement, if
there were at least two parts in both the inner and outer tube
arrangements.
* * * * *