U.S. patent application number 13/274487 was filed with the patent office on 2012-02-09 for thermoplastic medical device.
This patent application is currently assigned to BOSTON SCIENTIFIC SCIMED, INC.. Invention is credited to Yem Chin, Paul Scopton, Shen-Ping Zhong.
Application Number | 20120035591 13/274487 |
Document ID | / |
Family ID | 34962809 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120035591 |
Kind Code |
A1 |
Zhong; Shen-Ping ; et
al. |
February 9, 2012 |
THERMOPLASTIC MEDICAL DEVICE
Abstract
An medical device such as a guidewire or a catheter having a
flexible elongate component which comprises a thermoplastic rigid
rod polymer, which component may comprise a bundle of threads, a
sleeve, a coil, a co-extrusion, a strut, or other suitable
component.
Inventors: |
Zhong; Shen-Ping;
(Shrewsbury, MA) ; Chin; Yem; (Burlington, MA)
; Scopton; Paul; (Winchester, MA) |
Assignee: |
BOSTON SCIENTIFIC SCIMED,
INC.
Maple Grove
MN
|
Family ID: |
34962809 |
Appl. No.: |
13/274487 |
Filed: |
October 17, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10811277 |
Mar 25, 2004 |
8067073 |
|
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13274487 |
|
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Current U.S.
Class: |
604/528 |
Current CPC
Class: |
A61L 31/10 20130101;
A61L 29/18 20130101; Y10T 428/13 20150115; Y10T 428/139 20150115;
Y10T 428/1352 20150115; Y10T 428/1303 20150115; Y10T 428/1393
20150115; Y10T 428/1359 20150115; A61L 29/085 20130101; A61L 31/18
20130101 |
Class at
Publication: |
604/528 |
International
Class: |
A61M 25/09 20060101
A61M025/09 |
Claims
1. A guidewire, comprising: an atraumatic distal tip; a distal end;
a proximal end; an elongate core made from a thermoplastic rigid
rod polymer, the core extending from the atraumatic distal tip to
the proximal end; and a polymeric sheath disposed over the
core.
2. The guidewire of claim 1, wherein the elongate core comprises a
plurality of long, flexible elements disposed in parallel.
3. The guidewire of claim 2, wherein the plurality of long,
flexible elements is made from a first polymer which is a
substituted poly(1,4-phenylene).
4. The guidewire of claim 3, wherein the first polymer comprises a
plurality of benzoyl substituted 1,4-phenylene units.
5. The guidewire of claim 2, wherein the elongate core is a core
wire.
6. The guidewire of claim 5, wherein the core wire extends from a
position proximate the proximal end of the guidewire to a position
proximate the distal end of the guidewire.
7. The guidewire of claim 5, wherein a substantial length of the
core wire has a circular cross sectional shape.
8. The guidewire of claim 5, wherein a substantial length of the
core wire has a rectangular cross sectional shape.
9. The guidewire of claim 5, wherein a substantial length of the
core wire has a cruciate cross sectional shape.
10. The guidewire of claim 1, further comprising a sleeve disposed
on the polymeric sheath, the sleeve made from the thermoplastic
rigid rod polymer.
11. The guidewire of claim 10, wherein the sleeve is an extruded
tube.
12. The guidewire of claim 10, wherein the sleeve is a coil.
13. The guidewire of claim 10, wherein the sleeve is formed from a
wound flat tape.
14. The guidewire of claim 10, wherein the sleeve is a mesh.
15. The guidewire of claim 10, wherein the sleeve is a weave.
16. The guidewire of claim 1, wherein the guidewire further
comprises a hydrogel coating.
17. The guidewire of claim 16, wherein the hydrogel coating
includes a therapeutic agent.
18. The guidewire of claim 1, further comprising a paramagnetic
material.
19. The guidewire of claim 18, wherein the paramagnetic material is
gadolinium (III).
20. The guidewire of claim 1, wherein the thermoplastic rigid rod
polymer is cross-linked.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 10/811,277, filed Mar. 25, 2004.
FIELD
[0002] The present invention generally relates to medical devices.
More particularly, the present invention relates to catheters
comprising an improved material.
BACKGROUND
[0003] Medical devices often require a confluence of
characteristics not readily achievable in a single device. For
instance, in medical devices such as guidewires and catheters, the
device is often navigated distally through a tortuous vascular
system. This requires high levels of pushability, torqueability,
and flexibility while retaining a narrow cross-sectional area. It
is also desired to have a device which minimizes the trauma to the
surrounding vessels. One way to minimize this trauma is through a
soft distal tip. Other characteristics that are often desirable
include MRI compatibility and radiopacity. There is thus an ongoing
need to provide alternative structures and designs for such medical
devices.
SUMMARY
[0004] One example embodiment pertains an elongated medical device
having an flexible elongated element formed from a thermoplastic
rigid-rod polymer such as substituted poly(1,4-phenylene). The
element may provide a significant portion of the medical devices
mechanical characteristics such as torqueability, pushability, and
flexibility.
[0005] Another example embodiment pertains to an a guidewire
comprising a elongated member made from a thermoplastic rigid-rod
polymer. The elongated member may be a core wire of the guidewire.
The core wire may run from substantially the proximal portion of
the guidewire to the distal portion of the guidewire. The core wire
may have a generally circular cross-sectional shape or may have a
rectangular or X-shaped cross-sectional shape. The guidewire may
include a sheath made from the thermoplastic rigid-rod polymer or
may include more than one sheath made from the thermoplastic
rigid-rod polymer. The sheath may be an extruded sleeve or may be a
braided sleeve. The braid may be a diamond braid or may be a
crisscross braid. The guidewire may include a core having a
plurality of fine threads of the polymer extending through a
substantial length of the guidewire. The guidewire may have a first
section having a solid core of the polymer and a second section
having a plurality of fine threads of the polymer. The guidewire
may have variable stiffness which may be provided by controlling
the outer diameter of a polymer shaft.
[0006] Another example embodiment pertains to a catheter such as a
guide catheter. The elongated member may be a sleeve made from the
thermoplastic rigid-rod polymer. The sleeve may include two or more
layers of the polymer. The sleeve may be braided, either in a
diamond pattern or a crisscross pattern. The braided layer may be
coated with another polymer and thereby impregnated with another
polymer. The sleeve may also be woven. The sleeve may be a coiled
polymer ribbon or may be a spring. The polymer of the sleeve may be
blended or co-extruded with another polymer. The other polymer may
be another thermoplastic. The blend or thickness of the layers of
the coextrusion may vary along the length to provide different
mechanical characteristics along desired portions.
[0007] Another example embodiment pertains to a balloon catheter
such as an angioplasty or stent-delivery catheter having a balloon
sleeve made from a thermoplastic rigid-rod polymer. The balloon
sleeve may have a first layer that is the polymer and a second
layer that is another polymer, such as a non-crosslinked nylon. The
balloon may have a wall formed using variable coextrusion, with
this polymer used where certain characteristics such as
non-compliance are desired and another polymer where other
characteristics are desired. The balloon wall may be formed from a
weave or mesh of this polymer coated with or overlaying another
polymer.
[0008] The above summary of some example embodiments 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
[0009] 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:
[0010] FIG. 1 depicts a diagrammatic cross-sectional view of a
guidewire;
[0011] FIG. 2 depicts a diagrammatic cross-sectional view of a
guidewire;
[0012] FIG. 3 depicts a lateral cross-section of the guidewire of
FIG. 2;
[0013] FIG. 4 depicts a partial plan view of a guide catheter;
[0014] FIG. 5 depicts a lateral cross-section of the guide catheter
of FIG. 4;
[0015] FIG. 6 depicts a partial plan view of a guide catheter;
[0016] FIG. 7 depicts a partial plan view of a balloon catheter;
and
[0017] FIG. 8 depicts a perspective view of a stent.
[0018] 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 EXAMPLE EMBODIMENTS
[0019] As used in this specification and the appended claims, the
singular forms "a", "an", and "the" may include plural referents
unless the content clearly dictates otherwise. 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.
[0020] The following detailed description should be read with
reference to the drawings in which similar elements in different
drawings are numbered the same. The drawings, which are not
necessarily to scale, depict illustrative embodiments and are not
intended to limit the scope of the invention.
[0021] The terms torqueability, pushability and flexibility are
herein defined as follows. Torqueability is the ability to transmit
a rotational force from a proximal portion to a distal portion.
Torqueability may be advantageous if a guidewire is shaped to
conform to specific vasculature, and the guidewire needs to be
specifically oriented to take full advantage of its shape.
Pushability is the ability to transmit a longitudinal force from a
proximal portion to a distal portion so that the longitudinal
displacement of the distal portion is approximately the same as the
longitudinal displacement of the proximal portion. In contrast, a
device that does not exhibit a high degree of pushability would
displace laterally near the proximal portion, creating bends or
curves in the device. Flexibility is the ability of a device to
bend without breaking or elastic deformation.
[0022] FIG. 1 is a diagrammatic cross-sectional view of a guidewire
2. Guidewire 2 includes a core member 4 and an outer lubricious
sheath 6. Guidewire 2 may also include an atraumatic distal tip 8
and one or more radiopaque markers 10 or may include a radiopaque
material incorporated into one or more of the materials. For
example, a radiopaque material may be incorporated into core member
4 or distal tip 8. Core member 4 is preferably made from a
thermoplastic rigid rod polymer. Consequently, guidewire 2 may be
compatible with magnetic resonance imaging while retaining
necessary torqueability, pushability and flexibility requirements.
Core member 4 may have a variable cross section. For instance, it
may be distally tapered, it may have tapering regions and straight
regions, or it may have one or more necked region. Core member 4
may include another polymer such as polyimide, for example, in
additional to the thermoplastic rigid rod polymer.
[0023] Guidewire 2 may be formed by extruding core member 4 and
extruding sheath 6 over core member 4. Sheath 6 may be lubricious
and may include therapeutic agents. For example, sheath 6 may
include PTFE or may include a drug infused hydrogel. Alternatively,
core member 4 may be formed by coextruding the thermoplastic rigid
rod polymer with another compatible polymer. The coextrusion
process may be controlled to extrude variable amounts of the
thermoplastic rigid rod polymer and the other polymer to produce a
variable stiffness core member. Of course, other embodiments are
contemplated. For example, core member 4 may be formed from
coextruding a first blend 12 and a second blend 14, each blend
including a thermoplastic rigid rod polymer.
[0024] FIG. 2 is a diagrammatic cross sectional view of an example
guidewire 102. Guidewire 102 includes a core 104 formed from a
plurality of elongate fibers 112, several of the fibers 112
including a thermoplastic rigid rod polymer, and may include a
lubricious or polymeric sheath 106. Of course, all fibers 112 may
include the thermoplastic rigid rod polymer. Alternatively, some
fibers 112 may include the thermoplastic rigid rod polymer and
other fibers 112 may include other polymers or materials. Some
fibers 112 may vary from a first material to a second material
along the length of the fiber. Fibers 112 are selected to provide
for desired characteristics along the length of guidewire 102. The
number and composition of fibers 112 affect the performance of
guidewire 102. Generally the more fibers that include a
thermoplastic rigid rod polymer, and the more of that material that
is in each fiber, the fewer fibers are needed to achieve a desired
level of torqueability and pushability. Other variations are
contemplated as well. For instance Fibers 112 may be of variable
length to permit the guidewire to taper distally. Thus, all fibers
112 would be present at a proximal portion and fewer fibers would
be present distally. Alternatively, each fiber may have a tapering
cross section. Variations in the cross-sectional shape are
contemplated. For instance, the cross-sectional shape of certain
fibers may be circular, pentagonal or square. Changing the
cross-sectional shape of the fibers may change the torqueability
while keeping the flexibility substantially the same, for example.
Fibers 112 are retained in a sheath 106 and may be bonded at distal
and proximal locations. Select fibers may also be bonded to each
other or to the sheath at various other locations throughout the
guidewire, which may help impart a desired shape to the guidewire.
FIG. 3 is a cross-sectional view through the section lines 3-3 of
FIG. 2. Guidewire 102 includes a core 104 formed from a plurality
of fibers 112 encased by a sheath 106.
[0025] FIG. 4 is a partial plan view of an example guide catheter
302 with selected portions removed. FIG. 5 is a transverse
cross-sectional view of the catheter of FIG. 4. Guide catheter 302
has a layer 304 including a thermoplastic rigid rod polymer and may
include additional layers 306 and 308. Layer 304 may be a smooth
tubular sheath or may be a weave, mesh, or coil. Layer 304 may
include other polymers. For example, if layer 304 is a weave,
strands made from other polymers may be woven in or the
thermoplastic rigid rod weave may be imbedded in a layer having
another polymer. Alternatively, the thermoplastic rigid rod polymer
may be blended with other polymers. Guide catheter 302 may have a
rigid rod thermoplastic layer directly bonded to a lubricious layer
such as a high density polyethylene. Of course, the rigid rod
thermoplastic layer may be a blended layer including one or more
other polymers.
[0026] FIG. 6 is a partial plan view of an example guide catheter
402 with selected portions removed. Guide catheter 402 has a
tubular layer 404 having elongate thermoplastic rigid rod fibers
410 retained between a first tubular layer 406 and a second tubular
layer 408. Fibers 410 have proximal ends 420 and distal ends 422
which may be embedded in a proximal retaining ring and a distal
retaining ring. Alternatively or additionally, fibers 410 may be
embedded in a retaining material 424 such as a polymer adhesive
such as epoxy or polyurethane. Selected segments of fibers 410 may
be embedded in a retaining material and other segments of fibers
410 may be free. This may be varied along the length of the
catheter to provide desired flexibilities and shapes of the
catheter. Fibers 410 may have a circular cross sectional shape,
rectangular cross-section shape, or other suitable shape.
[0027] FIG. 7 is a partial plan view of an example balloon catheter
502. Balloon catheter 502 includes a catheter shaft 504 defining an
inflation lumen fluidly connected to balloon 508 and may include a
guidewire lumen. Balloon 508 includes a balloon wall 510 made from
a rigid rod thermoplastic polymer, which may also be blended or
coextruded with other polymers. Balloon wall may have a thickness
of between 0.25 and 5.0 mils or between 0.3 and 1.0 mils while
retaining sufficient burst strength to do a typical angioplasty or
stent procedure. Balloon wall 510 may include a rigid rod
thermoplastic polymer mesh or weave embedded in another polymer
such as Nylon. The other polymer may be non-cross linked or it may
be cross-linked, depending on the desired properties.
[0028] FIG. 8 is a perspective view of an example stent 600. Stent
600 includes one or more struts 602 made from a rigid rod
thermoplastic polymer arranged in a lattice-work configuration.
Other suitable arrangements are contemplated. Stent 600 may include
a coating which provides enhanced lubricity, carries a therapeutic
agent, or provides other desired functionality. Stent 600 may also
include radiopaque or paramagnetic materials to provide enhanced
visibility. Stent 600 may be primarily polymeric, being made
substantially from the rigid rod thermoplastic polymer, and
consequently may be MRI compatible. Stent 600 may be made through
compression molding or through laser cutting a tubular extrusion
into the desired configuration, or through other suitable
method.
[0029] Any of the medical devices described herein may be provided
with a coating on a surface of the device. Such coatings may be
provided for various purposes including, but not limited to,
carrying a therapeutic agent for localized delivery to a target
area within the body; providing a lubricious surface to facilitate
introduction of the medical device into the patient during an
interventional procedure; improving the biocompatibility of the
medical device with the surrounding environment; or, for a
combination of such or other purposes. Among coatings that have
been proposed for implantable or insertable medical devices are
polymeric materials such as hydrogels.
[0030] Hydrogels are typically hydrophilic polymeric materials that
have the ability to absorb large amounts, up to many times the
weight of the hydrogel itself, of water or other polar molecules.
Hydrogels have been disclosed as coatings for implantable or
insertable medical devices or as materials for constructing the
device itself in, for example, U.S. Pat. Nos. 6,316,522; 6,261,630;
6,184,266; 6,176,849; 6,096,108; 6,060,534; 5,702,754; 5,693,034;
and, 5,304,121, each of which is assigned to Boston Scientific
Corporation or SciMed Life Systems, Inc. and is incorporated herein
in its entirety by reference. Hydrogels, such as those described in
the foregoing exemplary U.S. patents, can be based on synthetic or
naturally occurring materials, or a composite thereof; can be
biodegradable or substantially non-biodegradable; and, can be
modified or derivatized in numerous ways to render the hydrogel
more suitable for a desired purpose. For example, the hydrogel can
be modified by chemically cross-linking with, for example, a
polyfunctional cross-linking agent that is reactive with functional
groups covalently bonded to the polymer structure. The hydrogel
polymer can also be ionically cross-linked with, for example,
polyvalent metal ions. Many hydrogel polymers mentioned herein can
be both chemically and ionically cross-linked. Therefore,
chemically and ionically cross-linkable hydrogel polymers are not
necessarily mutually exclusive groups of hydrogel polymers.
[0031] Cross-linking of a hydrogel polymer can be advantageous, for
example, to provide a more rigid material. Cross-linking may also
be conducted, for example, to render the hydrogel less soluble in a
particular environment or to modify the ability of the hydrogel
polymer to absorb water or to modify the manner in which water or
other molecules, compounds or groups are associated with the
hydrogel polymer Examples of hydrogel polymers that can be adapted
to render a medical device lubricious surface, without limitation,
polyacrylates; poly(acrylic acid); poly(methacrylic acid);
polyacrylamides; poly(N-alkylacrylamides); polyalkylene oxides;
poly(ethylene oxide); poly(propylene)oxide; poly(vinyl alcohol);
polyvinyl aromatics; poly(vinylpyrrolidone); poly(ethyleneimine);
polyethylene amine; polyacrylonitrile; polyvinyl sulfonic acid;
polyamides; poly(L-lysine); hydrophilic polyurethanes; maleic
anhydride polymers; proteins; collagen; cellulosic polymers; methyl
cellulose; carboxymethyl cellulose; dextran; carboxymethyl dextran;
modified dextran; alginates; alginic acid; pectinic acid;
hyaluronic acid; chitin; pullulan; gelatin; gellan; xanthan;
carboxymethyl starch; chondroitin sulfate; guar; starch; and
copolymers, mixtures and derivatives thereof.
[0032] Paramagnetic materials such as paramagnetic ions and
paramagnetic particles may be incorporated into a medical device
such as those described above. The paramagnetic materials may be
incorporated into one or more of the polymers of the medical
device. Paramagnetic materials are typically those that have a
strong magnetic moment relative to detectable protons in water or
other molecules, compounds or groups in the vicinity of the
paramagnetic materials. Elements with atomic numbers 21-29, 42, 44,
and 58-70, such as chromium (III), manganese (II), iron (III), iron
(II), cobalt (II), copper (II), nickel (II), praesodymium (III),
neodymium (III), samarium (III), ytterbium (III), gadolinium (III),
terbium (III), dysprosium (III), holmium (III) and erbium (III) are
examples of paramagnetic elements that may be suitable. The
addition of paramagnetic materials may enhance MRI visualization of
the medical device, for example.
[0033] A thermoplastic rigid rod polymer is a meltable polymer
having constitutional or configurational units that form a
generally linear chain that is rigid. Thermoplastic rigid rod
polymers therefore may have increased strength compared with other
thermoplastics. Thermoplastic rigid rod polymers may also have
improved processing characteristics and good compatibility with
other polymers compared with other polymers of similar strength.
Thermoplastic rigid rod polymers may be cross-linked by cooling
down from an extrusion process. Most other polymers require a
radiation or chemical process to cross-link. Thus, a medical device
made from a thermoplastic rigid rod polymer in combination with
another polymer may have a cross-linked portion, which may increase
strength, and a non-cross-linked portion, which may increase
softness, flexibility or other suitable attribute. Therefore a
device incorporating a thermoplastic rigid rod polymer may provide
a combination of physical properties not available with a different
polymer. Some of these polymers may be available commercially under
the PARMAX name from Mississippi Polymer Technologies.
[0034] It should be understood that this disclosure is, in many
respects, only illustrative. Numerous advantages of the invention
covered by this document have been set forth in the foregoing
description. Changes may be made in details, particularly in
matters of shape, size and arrangement of parts without exceeding
the scope of the invention. Those of skill in the art will readily
appreciate that other embodiments may be made and used which fall
within the scope of the claims attached hereto. The invention's
scope is, of course, defined in the language in which the appended
claims are expressed.
* * * * *