U.S. patent application number 10/822182 was filed with the patent office on 2004-09-30 for multilayer catheter balloon.
This patent application is currently assigned to Schneider (USA) Inc., a corporation. Invention is credited to Hamlin, Robert N..
Application Number | 20040191443 10/822182 |
Document ID | / |
Family ID | 23629775 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040191443 |
Kind Code |
A1 |
Hamlin, Robert N. |
September 30, 2004 |
Multilayer catheter balloon
Abstract
A method of producing laminated inflatable, substantially
inextensible expander members having composite properties enhancing
their use on intravascular catheters, such as angioplasty catheters
is described. Diverse polymeric compounds of differing properties
are coextruded to create a multilayer parison. The parison is
subsequently drawn and expanded in a blow molding operation to
yield an expander member exhibiting enhanced properties including
lubricity, burst-strength, limited radial expansion, bondability,
and rupture characteristics.
Inventors: |
Hamlin, Robert N.;
(Stillwater, MN) |
Correspondence
Address: |
FISH & RICHARDSON PC
225 FRANKLIN ST
BOSTON
MA
02110
US
|
Assignee: |
Schneider (USA) Inc., a
corporation
|
Family ID: |
23629775 |
Appl. No.: |
10/822182 |
Filed: |
April 9, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10822182 |
Apr 9, 2004 |
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09557473 |
Apr 24, 2000 |
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09557473 |
Apr 24, 2000 |
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08907170 |
Aug 6, 1997 |
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6132824 |
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08907170 |
Aug 6, 1997 |
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08692314 |
Aug 5, 1996 |
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08692314 |
Aug 5, 1996 |
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08415094 |
Mar 31, 1995 |
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08415094 |
Mar 31, 1995 |
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08105353 |
Aug 10, 1993 |
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08105353 |
Aug 10, 1993 |
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07727664 |
Jul 9, 1991 |
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5270086 |
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07727664 |
Jul 9, 1991 |
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07411649 |
Sep 25, 1989 |
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Current U.S.
Class: |
428/35.2 |
Current CPC
Class: |
A61M 2025/1031 20130101;
A61L 29/06 20130101; Y10T 428/1334 20150115; B29K 2023/06 20130101;
A61L 29/06 20130101; A61L 29/126 20130101; A61M 25/0045 20130101;
A61L 29/06 20130101; A61L 29/126 20130101; Y10T 428/1393 20150115;
A61M 25/1029 20130101; C08L 67/02 20130101; C08L 23/00 20130101;
C08L 67/02 20130101; C08L 75/04 20130101; A61M 25/0009 20130101;
Y10T 428/139 20150115; B29C 49/22 20130101; A61L 29/041 20130101;
Y10T 428/1397 20150115; A61M 25/1034 20130101; B29K 2023/083
20130101; A61L 29/041 20130101; B29K 2067/00 20130101; B29C 49/04
20130101; B29L 2031/7542 20130101; A61M 2025/1075 20130101 |
Class at
Publication: |
428/035.2 |
International
Class: |
B29D 022/00 |
Claims
1-25 (Canceled)
26. A method of producing a laminated expander member, the method
comprising: coextruding different polymeric materials to form a
multilayer parison comprising a first layer comprising a first
polymeric material including a liquid crystal polymer, and a second
layer comprising a second polymeric material different from the
first polymeric material; and forming the parison into the expander
member.
27. The method of claim 26, further comprising coextruding a third
layer disposed towards an exterior of the expander member relative
to the first and second layers, the third layer enhancing the
lubricity of the expander member.
28. The method of claim 26, further comprising biaxially orienting
the first layer.
29. The method of claim 26, wherein the first layer consists
essentially of liquid crystal polymer.
30. The method of claim 26, wherein the second layer is an adhesion
layer.
31. The method of claim 30, wherein the adhesion layer is disposed
toward the interior of the expander member relative to the first
layer.
32. The method of claim 26, wherein the expander member has a
radial expansion not exceeding three percent when inflated to seven
atmospheres.
33. The method of claim 26, wherein forming the parison into the
expander member comprises drawing the parison and expanding the
parison in a blow molding operation.
Description
BACKGROUND OF THE INVENTION
[0001] I. Field of the Invention
[0002] This invention relates generally to balloon catheters, and
more particularly to a method for fabricating a multi-layer balloon
composite exhibiting enhanced characteristics attributable to the
properties of the individual layers.
[0003] II. Discussion of the Prior Art
[0004] As an alternative to open-heart, coronary bypass surgery, a
technique referred to coronary transluminal angioplasty has been
developed following the pioneering introduction of the technique by
A. Gruntzig. In carrying out this procedure, a dilatation catheter
having an inflatable expander member (balloon) on the distal end
thereof is routed through the vascular system to a location within
a coronary artery containing a stenotic lesion. Following placement
of the expander member across the lesion, a fluid is introduced
into the proximal end of the catheter and is used to inflate the
expander member to a predetermined relatively high pressure whereby
the lesion is compressed into the vessel wall restoring patency to
the previously occluded vessel.
[0005] It is desirable that the composite expander member exhibit
the following characteristics:
[0006] 1. High burst (tensile) strength;
[0007] 2. Low radial expansion at elevated pressures;
[0008] 3. Ease of bonding to a catheter body;
[0009] 4. Failure characteristics avoiding pinhole ruptures;
and
[0010] 5. Low coefficient of friction.
[0011] The Schjeldahl et al. U.S. Pat. No. 4,413,989 owned by
applicants' assignee discloses a coronary transluminal angioplasty
catheter in which the expander member is formed from polyethylene
terephthalate in a drawing and blow molding process so as to
provide biaxial orientation to the material. Such PET balloons are
found to exhibit the desirable property of high burst strength and
relatively low radial expansion when inflated to seven atmospheres
or more. However, because the catheter body itself is generally
fabricated from a formulation containing silicon rubber,
polyethylene, PET or polyurethane, a problem exists when attempts
are made to bond the expander member to the distal end portion of
the catheter body. The PET polyester balloon tends not to adhere
easily to the catheter body especially in a thermal bonding
process.
[0012] Moreover, experience with polyethylene, PVC and
polypropylene expansion members has shown that at relatively high
pressures, pinhole leaks form which may create a high velocity jet
of inflation fluid capable of perforating the blood vessel when it
impinges on the vessel wall. Thus it would be desirable if the
expander member can be fabricated in such a way that it exhibits a
controlled mode of failure, i.e., a rapid rupture so that the
pressure is released over a significant area in a short time
frame.
SUMMARY OF THE INVENTION
[0013] The above-listed desirable characteristics are achieved in
accordance with the present invention by forming a multi-layer
balloon where the individual layers afford a desirable property to
the composite. It has been found that a layer of medium or
relatively high melt temperature material which also exhibits high
tensile strength with relatively low distensibility can be used to
provide the required high burst or tensile strength and low radial
expansion at high pressures required by the expander member in a
composite structure. This layer may be referred to as the tensile
layer or tensile ply. It may be a biaxially-oriented film of
relatively high crystallinity.
[0014] In the composite structure, the tensile layer is combined as
an outer layer with a chemically and physically compatible adhesion
or bonding inner layer which is fabricated from materials having
superior glue bonding or melt bonding characteristics. The bonding
layer also must have good interlayer adhesion characteristics with
the material used for the tensile layer. The bonding layer imparts
the necessary adhesion properties to properly bond the expander
member to the distal end portion of the catheter body. If melt
bonding is the desired mode, the material of the bonding layer
should have a lower melting point than that of the tensile layer so
that melt bonding of the composite may be readily achieved in the
fabrication process with minimal effect on the tensile ply. In this
regard, it should be noted that the bonding layer may or may not be
continuous or coextensive with the entire inner surface of the
tensile layer inasmuch as it is required generally only in the
vicinity of the expander/catheter interface surfaces.
[0015] Examples of materials exhibiting the required high tensile,
low distensibility and having medium melt temperatures include
certain copolymers such as ABS (acrylonitrile-butadiene-styrene),
ABS/nylon, ABS/polyvinyl chloride (PVC) and ABS/polycarbonate. Such
materials having high melt temperatures include acrylonitrile
copolymer, polyacrylamiede, polyacrylate and polyacrylsulfone.
Other materials having suitable characteristics include high melt
temperature polyesters such as polyethylene terephthalate (PET),
polybutylene terephthalate (PBT), polyethylene naphthalate (PEN),
liquid crystal polymer (LCP), polyester/polycaprolactone and
polyester/polyadipate; and high melt temperature polyethers
including polyetheretherketone (PEEK), polyethersulfone (PES),
polyetherimide (PEI) and polyetherketone (PEK), polymenthylpentene,
polyphenylene ether, polyphenylene sulfide, and styrene
acrylonitrile (SAN). It should be noted that LCP has a very high
melt temperature and SAN, a lower melt temperature than the other
listed polyethers. Additional compounds having the required tensile
properties which have a medium melt temperature include polyamides
such as nylon 6, nylon 6/6, nylon 6/66, nylon 6/9, nylon 6/10,
nylon 6/12, nylon 11 and nylon 12.
[0016] Suitable adhesion materials for the bonding layer having a
high distensibility but excellent melt bond and glue adhesion
properties with relatively low melt temperatures include ethylene,
propylene, ethylene vinylacetate and ethylene vinyl alcohol (EVA),
various ionomers, polyethylene type I-IV, polyolefins,
polyurethane, polyvinyl chloride, and polysiloxanes (silicones).
Those with low to medium melt temperatures include fluorocarbons
such as polychlorotriethylene (CTFE),
poly[ethylene-co-chlorotrifluoroethylene] (ECTFE) copolymer
ethylene tetrafluoroethylene (ETFE), copolymer tetrafluoroethylene
and hexafluoropropylene (FEP), perfluoroalkane (PFA) and
poly[vinylidene fluoride] (PVDF).
[0017] It will be appreciated that the particular combination
chosen would depend on the particular application and particular
catheter involved, and that an array of multilayer expanders of
different composition combinations particularly applicable to
different situations can be produced. In addition, specific
properties required for addressing a specific stenosis could be
utilized to produce a tailor-made expander.
[0018] More particularly with respect to the process, a tubular
parison is first generated in a co-extrusion process whereby
different polymeric materials are coaxially layered. Subsequently,
the parison is inserted in a blow molding fixture, allowing the
tube to be longitudinally drawn and radially expanded until the
composite film is oriented, the maximum O.D. of the expander member
is defined and a desired film thickness is achieved. For example,
in forming the parison, PET of a predetermined viscosity may be
coextruded with polyethylene where, forming the parison, the
polyethylene lines the lumen thereof. When the expander member is
formed from the parison in the blow molding operation, the PET
layer affords the desired burst strength and limited radial
expansion characteristic while the polyethylene layer enhances the
ability to bond the resulting balloon to the catheter body.
[0019] The characteristic of lubricity may also be added by coating
the exterior of the composite with a suitably lubricious plastic
exhibiting high hydrophilic characteristics. Suitable lubricious
hydrophilic materials include polycaprolactam polyvinylindol,
N-vinylpyrrolidone, various hydrogels, and other hydrophilic
lubricious polymeric materials.
[0020] One successful embodiment of the system of the invention
utilizes a combination of polyethylene terephthalate (PET) as the
tensile layer in combination with a bonding layer of polyethylene.
The composite PET/polyethylene balloon was coated on the exterior
of the PET with polycaprolactam. By forming a three-layer tubular
parison having a layer of plastic with known rupture
characteristics, the polyethylene layer may provide the bondability
attribute, the PET, the limited radial expansion characteristic
and/or the controlled rupture characteristic while polycaprolactam
again affords the lubricity.
[0021] Of course, the known rupture or failure characteristics
involve the failure by bursting or large scale rupture of the
tensile layer rather than the development of small or pin hole
leaks in which a small stream of high pressure fluid is released.
This minimizes possible damage to surrounding tissue caused by high
pressure fluid leakage from the membrane.
DESCRIPTION OF THE DRAWINGS
[0022] The various features, characteristics and advantages of the
invention will become apparent to those skilled in the art from the
following detailed description of a preferred embodiment,
especially when considered in conjunction with the accompanying
drawings in which:
[0023] FIG. 1 is a process flow chart illustrative of the present
invention;
[0024] FIG. 2 is a partial schematic illustration of apparatus for
manufacturing parisons in a co-extrusion process;
[0025] FIG. 3 is a cross-sectional view of a two-component
co-extrusion die useful in forming a two-layer parison;
[0026] FIG. 4 illustrates schematically an apparatus for blow
molding the parison into a biaxially oriented multilayer expander
member;
[0027] FIG. 5 shows the expander joined to the distal end of a
catheter; and
[0028] FIG. 6 depicts an alternative embodiment of the multilayer
expander member.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0029] With reference to FIG. 1, in fabricating the multilayer
expander member in accordance with the present invention, the first
step in the process is to create a parison which when heated and
then drawn and blown creates a balloon or expander member for use
on an intravascular catheter. The extruding apparatus is indicated
generally by numeral 10 in FIG. 2 and is seen to comprise a motor
12 coupled in driving relationship to a gear box 14 whose output
shaft comprises a coarse-pitched archimedian screw 16 rotating
within a heated barrel 18. In accordance with known practice, the
screw generally has three distinct sections. In the "feed" section
20, directly beneath the feed hopper 22, the screw channel depth is
constant and relatively large and serves to convey solid polymer
material from the hopper. The depth of the flute in the
"compression" section 24 is uniformly tapered and designed to
compact the plastic and force it into contact with the barrel 18 to
enhance melting. The melting is achieved mainly by a combination of
heat conducted from electrical heating elements 26 contained in the
barrel and the heat generated by the intense shearing in the molten
layer formed between the barrel and the solid material. Numeral 28
identifies the "metering" section of the screw in which the flute
depth is constant and relatively small. It controls the output from
the extruder in terms of quantity, steadiness and homogeneity.
Disposed at the end of the screw 16 is an extruder die 30 which, in
the case of the present invention, provides for co-extrusion of at
least two different plastics. The first plastic passing through
extruder 10 combines with a second plastic exiting a substantially
identical extruder shown schematically at 32 to create a
concentrically layered tubular parison, the cross-section of which
is seen in the view of FIG. 4.
[0030] FIG. 3 is a cross-sectional view taken through a two-port
co-extrusion die. For example, the output from the metering section
28 of the extruder 10 may be fed into die port A in FIG. 3 while
that from the metering section of the screw of extruder 32 feeds
port A. The molten plastic flows together to form a layer with the
plastic entering port B surrounding the plastic entering port A. As
the plastic is made to flow through the die, air is also introduced
through the central bore 34 of the die 30 to prevent the collapse
of the tubular shaped exudate.
[0031] In accordance with one aspect of the invention, the plastic
entering port A, for example, may comprise a polyolefin or PVC
while that forced into port B may be a homopolyester, preferably
PET, of a predetermined viscosity. With these two constituents, the
resulting tubular parison will have the PVC as the inner tubular
layer and the PET as its outer layer. The thickness of the
individual layers will be determined by the mass flow ratios
provided by the respective extruders. The final diameter of the
parison is determined by the size of the die exit opening, the
total flow of material into ports A and B and the take-away or draw
speed.
[0032] The balloon itself is fabricated in a blow molding operation
wherein the parison 40 is inserted into the blow mold 42 as shown
in FIG. 4 and air or other suitable fluid is introduced through the
port 44 at a predetermined pressure. The mold 42 has a cavity 46
corresponding to the desired size of the balloon to be
produced.
[0033] After the tubular parison is disposed in the mold, the mold
is heated to thereby raise the tubing temperature to a point
between the second order transition temperature and the first order
transition temperature of the polyester polymer.
[0034] Of course, the inner layer can be caused to adhere to and
attach the balloon to the exterior of the tubular catheter body in
any desired manner. The material of the inner layer may be such
that relatively low melt temperature material can be utilized to
achieve a permanent melt bond. Preferably, the exterior of the
tubular catheter body is provided with a coating of the same or
similar material to that of the inner layer of the multilayer
balloon structure such that the materials bonded are substantially
identical. This also allows the continuous joint to be made
utilizing melt bonding the materials. In this regard, it is desired
that the material forming the bonding layer of the multilayer
system have a melting temperature sufficiently below that of the
material of the tensile layer so that the melt bonding can be
achieved without affecting the future physical characteristics of
the system.
[0035] As described above, it is desirable that the expander member
itself exhibits rather high tensile strength properties. This means
exhibiting a burst pressure well in excess of 7 atmospheres while
undergoing a radial expansion less than about 3-10 percent. The
actual strength, of course, will depend on the relative tensile
strength of the material and thickness of the material layer. In
addition, these extruded materials are ones not prone to pinhole
leaks in the process of the invention in most cases results in a
mode of failure, should failure occur, in the form of a rapid
rupture which releases the internal pressure over a considerable
area in a short time frame so that damage to the vessel is
minimized.
[0036] By first drawing the tubular parison and subsequently blow
molding same, biaxial orientation takes place whereby the PET layer
56, while remaining flexible, becomes strong as regards the
inflation pressure at which the material will burst. When it is
desired to bond the finished balloon onto the catheter body as
illustrated in FIG. 5, the inner layer 48 of PVC can readily be
bonded to an outer PVC tubular body 50 and to an inner tubular body
52, such as by adding adhesive 54 between the outer layer 56 and
the inner layer 48. The space between the coaxially disposed tubes
allows for injection of a balloon inflation fluid. Balloons
produced in accordance with the invention may exhibit a burst
pressure well in excess of 7 atmospheres while radially expanding
less than about 3-10 percent. While the PVC layer 48 adds little to
the burst strength of the composite, it does facilitate the
attachment of the balloon to the exterior of the tubular catheter
body.
[0037] If it is desired to increase the lubricity of the composite
balloon, this may be accomplished by dipping or other coating the
multilayer balloon in a suitable hydrophilic material such as
polyvinylidol, N-vinylpyrolodone, hydrogels, etc.
[0038] With reference to FIG. 6 and rather than utilizing PET in
combination with PVC, a balloon having enhanced properties maybe
created by co-extruding a high molecular weight crystalline
polyester 60 with a lower molecular weight amorphous polyester 62
in forming the parison. An outer layer of filled polymer 64 adds
lubricity. As known in the art, adhesive 66, 68 may be juxtaposed
between layers 60, 62 and 64. Following drawing and radial
expansion in a blow molding operation, the resulting balloon is
found to exhibit high burst strength, low radial expansion and
superior bondability as compared to conventional PET single-layer
balloons.
[0039] The rupture characteristics of a polymer layer can be
modified to increase the rupture rate by adding filler material.
The filler materials may be an inert type, such as calcium
carbonate, generally in powder form, carbon in fiber form, or an
incompatible second phase polymer. Incompatible phase polymer
systems afford many advantageous characteristics and are a function
of the dispersion between the two phases. Materials which might be
candidates for this are polypropylene and selected rubbers,
polyester and polypropylene.
[0040] This invention has been described herein in considerable
detail in order to comply with the Patent Statutes and to provide
those skilled in the art with the information needed to apply the
novel principles and to construct and use such specialized
components as are required. However, it is to be understood that
the invention can be carried out by specifically different
equipment and devices, and that various modifications, both as to
the equipment details and operating procedures, can be accomplished
without departing from the scope of the invention itself.
* * * * *