Register or Login To Download This Patent As A PDF
|United States Patent Application
;   et al.
January 19, 2012
Medical Device Balloons Containing Thermoplastic Elastomers
A dilatation balloon, the dilatation balloon having a multilayer
structure wherein the multilayer structure comprises a thermoplastic
elastomer coextruded with a non-compliant structural polymer, the
thermoplastic elastomer as an outer layer and the non-compliant
structural material is an inner layer.
Hamilton; Bruce; (Lowell, MA)
; Sahatjian; Ronald A.; (Lexington, MA)
BOSTON SCIENTIFIC SCIMED, INC.
September 23, 2011|
|Current U.S. Class:
||606/194; 264/209.1; 606/191 |
|Class at Publication:
||606/194; 606/191; 264/209.1 |
||A61M 29/02 20060101 A61M029/02; B29C 47/06 20060101 B29C047/06|
15. A dilatation balloon, the dilatation balloon comprising a multilayer
structure wherein said multilayer structure comprises: a thermoplastic
elastomer coextruded with a non-compliant structural polymer, said
thermoplastic elastomer as an outer layer and said non-compliant
structural material is an inner layer, the thermoplastic elastomer outer
layer is thinner than the non-compliant structural material inner layer.
16. The dilatation balloon of claim 15 wherein said non-compliant
structural polymer is polyethylene terephthalate.
17. The dilatation balloon of claim 16 wherein said polyethylene
terephthalate is biaxially oriented.
18. The dilatation balloon of claim 15 wherein said non-compliant
structural polymer is nylon.
19. The dilatation balloon of claim 15 wherein said thermoplastic
elastomer is a thermoplastic polyamide elastomer.
20. The dilatation balloon of claim 15 wherein said thermoplastic
elastomer is a thermoplastic polyester elastomer.
21. The dilatation balloon of claim 15 wherein said thermoplastic
elastomer is a block copolymer of polyether glycol and polybutylene
22. The dilatation balloon of claim 15 wherein said inner layer is about
0.2-1.5 mil think.
23. The dilatation balloon of claim 15 wherein said outer layer is about
0.2-0.5 mil thick.
24. The dilatation balloon of claim 15 wherein said inner layer is
coextensive with said outer layer.
25. The dilatation balloon of claim 15 further comprising at least one
additional layer comprising a non-compliant structural polymer material,
the at least one additional layer is an intermediate layer.
26. The dilatation balloon of claim 15 wherein said non-compliant
structural polymer material of the inner layer is different than the
non-compliant structural polymer material of the intermediate layer.
27. The dilatation balloon of claim 15 wherein said non-compliant
structural polymer material is a blend of two or more structural
polymers, a blend of a structural polymer with a minor amount of another
polymer or a blend of a structural polymer with a thermoplastic
28. The dilatation balloon of claim 15 further comprising an adhesive
layer disposed between the inner layer and the outer layer.
29. The dilatation balloon of claim 15 wherein said adhesive layer
comprises a blend of said thermoplastic elastomer and said non-compliant
30. A dilatation balloon, the dilatation balloon comprising a multilayer
structure, the multilayer structure comprising: a thermoplastic elastomer
coextruded with a non-compliant structural polymeric material, the
thermoplastic elastomer as both an inner thermoplastic elastomer layer
and an outer thermoplastic elastomer layer disposed upon an intermediate
structural layer of the non-compliant structural polymeric material.
31. The dilatation balloon of claim 30 wherein said non-compliant
structural polymer is polyethylene terephthalate.
32. The dilatation balloon of claim 30 wherein said non-compliant
structural polymer is nylon.
33. The dilatation balloon of claim 30 wherein said thermoplastic
elastomer is a thermoplastic polyamide elastomer.
34. The dilatation balloon of claim 30 wherein said inner layer and said
outer layer are coextensive with said intermediate layer.
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS
 This application is a Continuation of and claims priority to U.S.
patent application Ser. No. 12/861,633, filed Aug. 23, 2010 which is a
Continuation of U.S. patent application Ser. No. 10/855,816, filed May
27, 2004, which is a Divisional application of Ser. No. 09/557,258 filed
Apr. 24, 2000 and issued as U.S. Pat. No. 6,896,842, which is a
Continuation application of Ser. No. 09/129,029 filed Aug. 4, 1998 and
issued as U.S. Pat. No. 6,086,556, which is a Continuation application of
Ser. No. 08/653,117 filed May 24, 1996 and issued as U.S. Pat. No.
5,797,877, which is a Continuation application of Ser. No. 08/530,825
filed Sep. 20, 2995 now abandoned, which is a Continuation application of
Ser. No. 08/364,431 filed Dec. 27, 1994 now abandoned, which is a
Continuation application of Ser. No. 08/130,283 filed Oct. 1, 1993 now
abandoned, the entire contents of all of which are hereby incorporated by
BACKGROUND OF THE INVENTION
 The present invention relates to catheters that can be placed in
bodily conduits. The invention particularly relates to dilatation
balloons and catheters using such balloons for administering treatments
to widen constricted passages in, for example, angioplasty,
valvuloplasty, or urological procedures.
 One example of such a procedure, angioplasty, is used to treat a
stenosis, i.e. to restore adequate blood flow to a region of a blood
vessel which has been narrowed to such a degree that blood flow is
restricted. Frequently the stenosis can be expanded so that the vessel
will permit an acceptable blood flow rate. Coronary angioplasty, for
example, includes the insertion of a balloon catheter through a patient's
coronary artery to an arterial stenosis and injecting a suitable fluid
into the balloon to inflate it, hence expanding the stenosis radially
outwardly. Angioplasty has proven to be a successful alternative to
coronary arterial bypass surgery.
 Typically, balloon catheters have a balloon fastened at least one
end around the exterior of a hollow catheter shaft. The hollow interior
of the balloon is in fluid flow relation with the hollow interior of the
shaft. The shaft then may be used to provide a fluid supply for inflating
 Presently used catheter balloons may be classified as compliant or
non-compliant balloons. Compliant balloons expand and stretch with
increasing pressure within the balloon, and are made from such materials
as polyethylene or polyolefin copolymers. Non-compliant balloons, made
from such materials as polyethylene terephthalate (PET) or polyamides,
remain at a preselected diameter as the internal balloon pressure
increases beyond that required to fully inflate the balloon.
 Compliant balloon materials provide a degree of softness to the
balloon which aids its passage through, e.g., blood vessels with minimal
trauma. Known compliant balloon materials also can display good abrasion
and puncture resistance at thicknesses typically used for medical device
balloons. However, as mentioned above, they do not remain at the desired
diameter with increasing pressure. Such compliant balloons also lack
sufficient hoop strength to achieve high dilating forces.
 A non-compliant balloon, that is one remaining at a preselected
diameter regardless of increasing pressures is often desirable. Typical
non-compliant balloon materials do not exhibit the same degrees of
softness and abrasion resistance as the compliant balloons.
 It would be desirable, for many treatment conditions, to have a
dilatation balloon exhibiting the combined characteristics of softness,
abrasion and puncture resistance, hoop strength, and the ability to
maintain a preselected diameter as the internal pressure within the
balloon is increased. The balloon described herein was developed to
address that need.
SUMMARY OF THE INVENTION
 In one embodiment, the invention is a dilatation balloon for use in
a medical catheter device. The dilatation balloon includes a
thermoplastic elastomer in combination with a non-compliant structural
polymeric material. The preferred thermoplastic elastomer includes an
engineering thermoplastic elastomer, for example a polyether
glycol/polybutylene terephthalate block copolymer. The thermoplastic
elastomer may be combined with the non-compliant structural polymeric
material as an outer elastomeric layer disposed upon an inner structural
layer of the non-compliant structural polymeric material, as both an
inner elastomeric layer and an outer elastomeric layer disposed upon an
intermediate structural layer of the non-compliant structural polymeric
material, or as a blend of the thermoplastic elastomer and the
non-compliant structural polymeric material.
 In another embodiment, the invention is a catheter for insertion
into a bodily conduit. The catheter includes a shaft having a lumen
internal to the shaft for delivery of fluid inflation media, and a
dilatation balloon bonded to the shaft and defining a chamber. The
chamber is in fluid communication with the lumen to permit inflation of
the chamber. The dilatation balloon includes a thermoplastic elastomer in
combination with a non-compliant structural polymeric material, as
described above with respect to the balloon in accordance with the
 In yet another embodiment, the invention is a method for
fabricating a dilatation balloon for use in a medical catheter device.
The method involves producing a generally cylindrical balloon blank from
a combination of a thermoplastic elastomer and a non-compliant
structural, material, and shaping the balloon blank to produce the
 The balloon blank may be produced by disposing an elastomeric layer
including the thermoplastic elastomer upon a structural layer including
the non-compliant structural polymeric material to produce a layered,
generally cylindrical balloon blank. The thermoplastic elastomer and the
non-compliant structural polymeric material may be coextruded to produce
the balloon blank. Alternatively, the balloon blank may be produced by
preparing a blend of the thermoplastic elastomer and the non-compliant
structural polymeric material. A generally cylindrical balloon blank is
formed from the blend, and the balloon blank is then shaped to produce
the dilatation balloon. The balloon blank may be shaped to have a
generally cylindrical central portion and generally conical end portions.
BRIEF DESCRIPTION OF THE DRAWINGS
 For a better understanding of the present invention, together with
other objects, advantages, and capabilities thereof, reference is made to
the following Description and appended Claims, together with the Drawings
 FIG. 1 is an elevation view of a medical balloon catheter, partly
in section, in accordance with one embodiment of the present invention;
 FIG. 2a is a cross-sectional view of the balloon of FIG. 1, taken
along line 2a-2a, showing the balloon layers;
 FIGS. 2b, 2c, and 2d are cross-sectional views similar to that
shown in FIG. 2a (omitting the shaft distal end) illustrating balloons in
accordance with alternate embodiments of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 An exemplary embodiment of the balloon and catheter in accordance
with the invention is described herein. The angioplasty catheter includes
a balloon mounted at the distal end of a shaft including at least one
lumen for inflation of the balloon. The balloon is a generally tubular
body fabricated from a combination of a non-compliant structural
polymeric material and a thermoplastic elastomer (TPE). The combination
may be in the form of coextensive coextruded layers, otherwise disposed
layers, blends, or blended layers of these materials. Once the catheter
is in position within the patient's artery, a fluid inflation medium may
be introduced via the lumen to inflate the balloon to the preselected
 The term "structural polymer" or "structural polymeric material",
as used herein, is intended to mean any polymeric material suitable for
use in medical balloons and compatible with the TPE selected. As
mentioned above, the term "non-compliant", as used herein, is intended to
mean remaining at a preselected diameter as the internal pressure in the
balloon is increased above that required to fully inflate the balloon.
The structural layer of the balloon must be self supporting and capable
of supporting at least one TPE layer thereon. Suitable non-compliant
structural polymeric materials include, for example, modified polyesters,
polyethylene terephthalate (PET), modified polybutylenes, polyvinyl
chlorides, polyamides (e.g. Nylon), etc., or a combination thereof.
Preferred are biaxially oriented non-compliant structural materials; most
preferred is biaxially oriented PET.
 The term "thermoplastic elastomer" or "TPE", as used herein, is
intended to mean a polymeric material that combines the mechanical
properties of a thermoset rubber, i.e. resiliency, softness, and
toughness, with the production economics of a thermoplastic polymer. The
TPEs include styrenic block copolymers, polyolefin blends (TPOs),
elastomeric alloys, thermoplastic polyurethanes (TPUs), thermoplastic
copolyesters, and thermoplastic polyamides. These materials have varying
patterns of hard and soft segments included in the polymer chain or
compound. The hard segments melt or soften at processing temperatures,
producing a melt processable material for ease of fabrication. In block
copolymer TPEs, the hard and soft regions are in the same polymer chain.
Descriptions of various types of TPEs may be found in Modern Plastics
Encyclopedia 1988, Vol. 64, No. 10A, pp. 93-100 (October 1987), and in
Modern Plastics Encyclopedia 1990, Vol. 66, No. 11, pp. 122-131
(Mid-October 1989), both incorporated herein by reference.
 The preferred TPEs for the balloon described herein are engineering
thermoplastic elastomers (ETEs), which are randomized block copolymers
having polyester crystalline hard segments and amorphous glycol soft
segments. ETEs possess flexibility over a useful range of strain, and are
quite extensible when operating within their elastic limit. Another
advantage of ETEs for medical devices is their resistance to most
radiation, permitting sterilization by such means, although they must be
protected from UV radiation.
 The more preferred ETEs for use in the medical devices described
herein are randomized block copolymers of polyether glycol and
polybutylene terephthalate (PBT). These combine crystalline PBT hard
segments with melt stable glycol soft segments, and come in a wide range
of stiffness grades. Most preferred are those having a flexural modulus
of about 21,000-440,000 psi (as measured in accordance with ASTM D790,
Method 1), for example Hytrel.RTM. polymers (available from E.I. DuPont
de Nemours and Company, Wilmington, Del.).
 As mentioned above, the combination of a TPE and a non-compliant
structural polymer may be in the form of blends, coextensive coextruded
layers, otherwise disposed layers, or layers of blends of these
materials. Suitable blends include homogeneous and near-homogeneous
blends, which may be prepared by such conventional means as stirring,
mixing, compounding, etc.
 In a layered embodiment of the balloon, one or mare base structural
polymer layers are formed, for example by extrusion, from a non-compliant
structural polymer, as described above. Alternatively, the bass
non-compliant structural layer is formed from a blend of two or more
structural polymers, a blend of a structural polymer with a minor amount
of another polymeric material, or a blend of a structural polymer with a
minor amount of a TPE. As used herein, the term "minor amount" is
intended to mean an amount selected to make the additive no more than a
secondary component, for example less than 50 weight %, of the blend. The
material of the structural layer, however, must still contribute to the
balloon the properties described above for the structural material. This
base structural layer (or layers) is typically at least about 0.2-1.5 mil
thick, and gives the balloon its tensile strength so that the balloon
wall is self supporting.
 At least one additional, elastomeric outer layer about 0.2-0.5 mil
thick is coextruded with or--otherwise disposed on the base layer and,
typically, generally coextensive therewith. Normally, the elastomeric
layer. Is significantly thinner than the structural layer. The material
of this outer layer is based on a thermoplastic elastomer (TPE) which, in
some embodiments, may be combined in a blend with other polymers known to
be suitable for medical balloons. The amount of these other polymers,
however, should be within limits which would permit such a blend to
contribute to the balloon the properties described herein for such an
elastomeric layer. Especially preferred for this outer elastomeric layer
is a blend of an ETE with a small amount of a non-compliant structural
polymer, e.g. a blend of about 1-10 weight % PET, remainder Hytrel
 In some of the above-described layered balloons, it may be
advantageous to dispose or coextrude an adhesive or other polymer layer
between two or more of the layers. In one embodiment, an adhesive layer
may be included to improve adhesion between coextensive balloon layers
and, if desired, may be applied for adhesion of the medical device
balloon to a catheter shaft. In another embodiment, an additional polymer
layer may be included to contribute other desirable properties to the
balloon, for example to contribute further to the softness and/or
foldability of the balloon. In other embodiments, the adhesive or other
polymer may be blended with a structural and/or elastomeric layer to
contribute its properties to the balloon. For example, in a three layer
balloon an adhesive polymer may be blended with a structural polymer
layer to improve adhesion of inner and outer ETE layers to the structural
layer. The amount of adhesive or other polymer in such a blend is
selected to provide the desired enhancement of properties while
permitting the blend to possess the properties described herein for such
a layer. Examples of adhesive materials for forming this layer or blend
are Bynel.RTM. adhesive resin (E.I. DuPont de Nemours and Company,
Wilmington, Del.) or Plexar.RTM. adhesive resin (Quantum Chemical Corp.,
Cincinnati, Ohio). Selar.RTM. modified PET resin (E.I. DuPont. de Nemours
and company, Wilmington, Del.) is a suitable polymer intermediate layer
or blend additive for improving softness and foldability of the balloon.
Bynel and Plexar resins can also serve to improve the abrasion resistance
and puncture resistance of the balloon, and provide it with a softer
 In another embodiment of the balloon, a single layer balloon wall
is fabricated from a bland of a non-compliant structural polymer and a
TPE. The TPE, preferably the above-described polyether-glycol/PBT block
copolymer, is blended with the structural polymer in a TPE-to-structural
polymer ratio selected to provide the desired degree of softness and
abrasion resistance to the balloon without unduly compromising the hoop
strength or the desired inflated diameter. As mentioned above, such
blends may be homogeneous or near-homogeneous, and may be blended in any
of several ways known in the art. Typical polymer ratios for such a
single layer balloon are about 40:60 to 60:40, TPE:structural polymer.
 In other embodiments, the TPE/structural polymer blend used in the
above-described single layer balloon may be used as a structural layer in
combination with other layers, or may be blended to be used as an
elastomeric layer in a layered balloon. The polymer ratio for a blended
structural layer of such a balloon is typically about 40:60 to 60:40,
TPE:structural polymer; that for elastomeric inner or outer layers is
typically about 30:70 to 60:40, TPE:structural polymer. The exact ratios
within these ranges to produce specific balloon characteristics are
empirically determined with minimal experimentation. These blended layers
may be used with or without an adhesive or softening component or layer
as described above.
 The use of thermoplastic elastomers in medical device balloons
results in a superior balance of balloon properties when used as one or
more outer layers over a structural layer of currently used balloon
materials or other suitable structural polymers, or as outer and inner
layers surrounding such a structural layer. Alternatively, this superior
balance of balloon properties may be achieved by using TPEs as a blend
with currently used balloon materials or other suitable structural
polymers. By varying the fabrication method and/or layer materials and/or
blend materials and ratios; as described herein, the structural and
surface properties of the ETE containing balloon may be precisely
tailored for a desired procedure.
 The description below of various illustrative embodiments shown in
the Drawings refers to engineering thermoplastic elastomers (ETEs).
However, it is not intended to limit the scope of the present invention,
but merely to be illustrative and representative thereof.
 Referring now to FIG. 1, catheter 10 in accordance with one
embodiment of the present invention includes shaft 12 having lumens 14
and 16 extending therethrough, and having a proximal end 18 and a distal
end 20. Distal end 20 extends to catheter tip 22. Dilatation balloon 24,
shown in FIG. 1 in its inflated state, surrounds shaft distal and 20.
Balloon proximal end 26 is bonded to shaft distal end 20 at a point
spaced from tip 22, and balloon distal end 28 is bonded to shaft distal
end 20 near tip 22, each, e.g., by a suitable adhesive (not shown).
Balloon 24 defines balloon chamber 30 which is in fluid communication
with lumen 14 via aperture 32. Thus, balloon 24 may be inflated by
passing a fluid inflation medium through lumen 14 and aperture 32 into
chamber 30. Lumen 16 may be used, for example, to contain a guidewire or
 As shown in FIGS. 1 and 2a, dilatation balloon 24 surrounding shaft
distal end 20 is made up of two layers, 34 and 36, of differing polymeric
materials Inner layer 34 is a structural layer of, e.g., PET
approximately 0.2-1.0 mil thick. Outer layer 36 has been co-extruded to
be co-extensive with layer 34, and is a layer of ETE, e.g. Hytrel
copolymer, about 0.2-0.5 mil thick.
 FIGS. 2b, 2c, and 2d each illustrate alternate embodiments of the
balloon of the invention in cross-section, similarly to FIG. 2a. For
simplicity, however, shaft distal end 20, although actually present in
the same position as shown in FIG. 2a, is not depicted in the view shown
in FIGS. 2b-2d.
 FIG. 2b illustrates in cross-section dilatation balloon 24a,
fabricated from single layer 38 of a blend of a structural polymer, e.g.
polyethylene terephthalate, with an ETE, for example Hytrel copolymer.
 FIG. 2c shows balloon 24b fabricated from, e.g., coextruded triple
layers, 34a, 36a, and 40. Structural layer 34a and ETE outer layer 36a
are similar to layers 34 and 36 of FIGS. 1 and 2a. In the embodiment
illustrated in FIG. 2c, however, an additional ETE layer, innermost layer
40, has been coextruded to be coextensive with layers 34a and 36a and
internal thereto. Innermost layer 40 provides additional tear resistance
to protect the balloon wall from damage from internal pressure. Layer 40
also provides for a softer, more foldable balloon.
 FIG. 2d illustrates balloon 24C, fabricated in a similar manner to
balloon 24 of FIGS. 1 and 2a, and having inner structural layer 34b and
ETE outer layer 36b. Thin intermediate adhesive layer 42 of, e.g., Bynel
resin is coextruded with and between layers 34b and 36b to be coextensive
therewith, acting to bond together more securely layers 34b and 36b.
 In other alternate embodiments, one or more of layers 34, 34a, and
34b may be a blend of a structural polymer with an ETE. Also
alternatively, one or more of layers 36, 36a, 36b, or 40 may be a blend
of ETE with a structural polymeric material. In the embodiment of FIG.
2c, a sufficient amount of a polymeric adhesive to improve bonding of the
layers may be blended into layer 34a. Alternatively, layer 34a may be,
e.g., a Selar resin balloon softening layer. Also alternatively, the
adhesive or other polymeric additive may be blended into, e.g., layer 34,
36, 36a, 40, etc., as described above. In other alternate embodiments,
not shown, the balloon may have more than one innermost and/or, outermost
ETE layer. For example, a balloon may be similar to that shown in FIG. 2a
but have an additional ETE layer between layers 34 and 36, or may be
similar to that shown in FIG. 2c but have an additional ETE layer between
layers 34a and one or both of layers 36a and 40.
 In operation, the catheter device including the novel dilatation
balloon is inserted into the vasculature of a patient, and is manipulated
into position by torquing, pushing, and pulling. Positioning of the
catheter is aided by the softness of the balloon provided by the TPE
component of the balloon. Once the catheter is in position, the balloon
is inflated to the preselected diameter, then deflated via the central
lumen of the shaft. The inclusion of a non-compliant structural polymer
in the balloon makes possible such preselection of the diameter. Upon
completion of the dilation procedure and deflation of the balloon, the
catheter is removed from the patient. Removal of the catheter is also
aided by the softness contributed to the balloon by the TPE component.
 The invention described herein presents to the art novel, improved
catheters and composite medical device balloons including thermoplastic
elastomers as (a) one or more layers in addition to one or more layers of
currently used balloon structural materials or other suitable structural
polymers, or (b) as a blend with such materials. The inclusion of TPE
results in a superior balance of balloon properties. For example, softer
feel; superior abrasion and puncture resistance; lower required
insertion, placement, and withdrawal forces; lower balloon resistance to
inflation and deflation pressure; superior refoldability, with fold
memory; and the ability to maintain a preselected diameter are all
achievable in a single balloon fabricated as described herein. Thus, the
balloon described herein can provide a non-compliant balloon with the
softness of a compliant balloon, as well a soft balloon with ranges of
burst strength and hoop strength equivalent to those of harder balloons.
The use of the adhesives and other layers or layer additives described
herein, especially the Bynel and Plexar adhesives and Selar additive
described, can offer advantageous adhesive and/or softening properties.
By varying the fabrication method and/or layer or blend materials and
ratios as described herein, the balance of structural and surface
properties of the TPE containing balloon may be precisely tailored for a
 While there has been shown and described what are at present
considered the preferred embodiments of the invention, it will be
apparent to those skilled in the art that modifications and changes can
be made therein without departing from the scope of the present invention
as defined by the appended Claims.
* * * * *