U.S. patent application number 14/918845 was filed with the patent office on 2016-02-11 for inflatable imbibed polymer devices.
The applicant listed for this patent is W. L. Gore & Associates, Inc.. Invention is credited to Alex R. Hobson, Michael Houghton, David R. King, Joseph E. Korleski, JR., Brian C. Lentz, Kenneth Newcomb, Peter J. Roeber, John Streeter.
Application Number | 20160038649 14/918845 |
Document ID | / |
Family ID | 38786972 |
Filed Date | 2016-02-11 |
United States Patent
Application |
20160038649 |
Kind Code |
A1 |
Hobson; Alex R. ; et
al. |
February 11, 2016 |
Inflatable Imbibed Polymer Devices
Abstract
The present invention provides a stretchable material suitable
for use in an inflatable medical device. The stretchable material
has at least one reinforcing polymer layer with a top and bottom
side forming a porous matrix which is imbibed with a sealing
material to infiltrate and substantially seal spaces of the porous
matrix and extend beyond the reinforcing polymer layer to form a
surface coating.
Inventors: |
Hobson; Alex R.; (Flagstaff,
AZ) ; Houghton; Michael; (Newark, DE) ; King;
David R.; (Lake Como, NJ) ; Korleski, JR.; Joseph
E.; (Newark, DE) ; Lentz; Brian C.; (Newark,
DE) ; Newcomb; Kenneth; (Wilmington, DE) ;
Roeber; Peter J.; (Wallingford, PA) ; Streeter;
John; (Flagstaff, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
W. L. Gore & Associates, Inc. |
Newark |
DE |
US |
|
|
Family ID: |
38786972 |
Appl. No.: |
14/918845 |
Filed: |
October 21, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11500794 |
Aug 7, 2006 |
9180279 |
|
|
14918845 |
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Current U.S.
Class: |
428/308.4 ;
428/306.6 |
Current CPC
Class: |
A61M 25/1006 20130101;
A61M 25/1018 20130101; A61M 25/1029 20130101; A61M 25/1034
20130101; A61M 2025/105 20130101; C08J 2327/18 20130101; A61F
2007/126 20130101; A61M 2025/1031 20130101; A61M 25/104 20130101;
A61L 29/126 20130101; B32B 1/02 20130101; C08J 7/0427 20200101;
C08J 2475/04 20130101; A61F 7/123 20130101; A61F 2250/0067
20130101; A61F 2/958 20130101; B32B 5/18 20130101; A61L 29/146
20130101; A61M 25/1027 20130101; A61M 2205/0216 20130101; A61M
25/10 20130101; Y10T 428/1386 20150115; B32B 1/08 20130101; A61L
29/085 20130101; Y10T 428/1352 20150115; A61M 2025/1075 20130101;
B32B 1/00 20130101; A61L 29/041 20130101; A61M 25/10184 20131105;
A61M 25/1025 20130101; A61M 2025/1052 20130101; A61M 25/1002
20130101 |
International
Class: |
A61L 29/12 20060101
A61L029/12; A61L 29/14 20060101 A61L029/14; A61M 25/10 20060101
A61M025/10 |
Claims
1. A stretchable material comprising a reinforcing polymer having a
porous matrix with void spaces and a sealing material imbibed into
the reinforcing polymer substantially sealing the porous matrix
void spaces and extending beyond the reinforcing polymer matrix to
form a surface coating.
2. The stretchable material of claim 1 wherein the surface coating
possesses a greater strain capability than the sealing
material.
3. The stretchable material of claim 1 wherein the sealing material
is an elastomer.
4. The stretchable material of claim 1 wherein the sealing material
is a nylon.
5. The stretchable material of claim 1 wherein the sealing material
is a polyether block amide.
6. The stretchable material of claim 1 wherein the sealing material
is a fluoropolymer.
7. The stretchable material of claim 1 wherein the polymer matrix
is anisotropic material stretched in only one direction.
8. The stretchable material of claim 1 wherein the polymer matrix
is isotropic.
9-23. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a unique material suited
for use in balloon catheters and, more particularly, to a low
profile non-shortening wrapped balloon configured to expand to a
predetermined diameter upon application of a predetermined pressure
thereto. The unique properties of the material of the present
invention enable wrapped balloons to be made without the use of
internal bladders.
[0002] Balloon catheters are well known in the art. Such catheters
are employed in a variety of medical procedures, including dilation
of narrowed blood vessels, placement of stents and other implants,
temporary occlusion of blood vessels, and other vascular uses.
[0003] In a typical application, the balloon is advanced to the
desired location in the vascular system. The balloon is then
pressure-expanded in accordance with a medical procedure.
Thereafter, the pressure is removed from the balloon, allowing the
balloon to contract and permit removal of the catheter. It is to be
appreciated that prior art balloons are typically formed of an
elastomeric material which is readily pressure-expanded, and also
readily contracts upon removal of the inflation pressure.
[0004] Some catheter balloons constructed of both elastomeric and
non-elastomeric materials have been described previously. U.S. Pat.
No. 4,706,670 describes a balloon dilatation catheter constructed
of a shaft made of an elastomeric tube and reinforced with
longitudinal inelastic filaments. This device incorporates a
movable portion of the shaft to enable the offset of the reduction
in length of the balloon portion as the balloon is inflated. A
major drawback to balloons of this type is the need for a bladder
which increases the profile of the balloon.
[0005] Traditionally, a fluoropolymer matrix which is filled with a
coating that does not extend outside the matrix permits the coating
to pull away from the matrix causing holes that eventually
demonstrate themselves in a "weeping" manner on the balloon. This
is believed to be due to the inadequate adhesion strength between
the matrix and the coating as well as the stress concentrations at
those interfaces.
[0006] There is a need in the art for a low profile wrapped balloon
which does not lengthen or shorten upon inflation and has the
ability to withstand inflation pressure strain without disruption,
while still remaining watertight without the use of a separate
bladder that adds to the balloon profile. The present invention
fulfills this need by providing a unique material which allows for
the elimination of a bladder. It also allows the balloon to readily
expand under pressure without leaking.
SUMMARY OF THE INVENTION
[0007] The present invention provides a stretchable material
comprising a reinforcing polymer having a porous matrix with void
spaces and a sealing material imbibed into the reinforcing polymer
substantially sealing the porous matrix void spaces and extending
beyond the reinforcing polymer matrix to form a surface coating
that can be stretched without the occurrence of holes through the
thickness of the material. In a preferred embodiment, a low angle
wrapped catheter balloon is comprised of a material which stretches
primarily in one direction and less than 54.7 degrees is formed
with said material. As the balloon is inflated to its working
diameter, the wrapped material rotates towards the balanced force
angle of 54.7 degrees. When rotating, the wrapped material also
strains perpendicular to the length of the wrap according to the
following geometric relationship
(Width.sub.F=Width.sub.I.times.(cos .theta..sub.F/cos
.theta..sub.I).sup.2.times.(tan .theta..sub.F/tan .theta..sub.I)
where F is Final and I is initial. This strain can exceed 500
percent in some balloons depending on the deflated to inflated
diameter ratio. The present invention allows for this strain to
occur without inducing holes or compromising the sealing coating.
The material is suitable for liquid or gas impermeable
applications.
[0008] The present invention further provides a balloon catheter
comprising a tubular catheter shaft having a longitudinal axis and
an inflatable bladderless wrapped balloon affixed to the catheter
shaft wherein the balloon comprises at least one reinforcing
polymer layer with a top and bottom side forming a porous matrix,
said porous matrix is imbibed with a sealing material that
infiltrates and substantially seals void spaces of the porous
matrix and extends beyond the reinforcing polymer layer to form a
surface coating. The surface coating is formed on at least one side
of the reinforcing polymer layer.
[0009] The present invention yet further provides a balloon
catheter with a surface coating thickness which is modulated to
allow for controlled porosity when strained due to inflation.
DESCRIPTION OF THE DRAWINGS
[0010] FIGS. 1A and 1B show cross sections of a reinforcing
polymer. FIG. 1A is the reinforcing polymer prior to imbibing. FIG.
18B shows the imbibed reinforcing polymer with two surface
coatings.
[0011] FIG. 2 shows a cross section of a reinforcing polymer with a
single surface coating.
[0012] FIG. 3 shows a composite film wrapped at a low angle on a
release coated core wire.
[0013] FIG. 4 shows a cross section of a balloon material layer
wrapped on a wire.
[0014] FIG. 5 shows a bladdedess balloon with a heat treated
inflation region.
[0015] FIG. 6 shows a schematic diagram depicting attachment via
two sealing means of a bladderless balloon to a hypotube.
[0016] FIG. 7 shows a cross section of a single coated anisotropic
material
[0017] FIG. 8 shows a cross section of a bladderless balloon for
fluid delivery at higher pressures.
[0018] FIG. 9 shows non-distensible seal wrapped onto a balloon
material layer.
[0019] FIG. 10 shows a cross section of a non-distensible seal
wrapped onto a balloon material layer.
DETAILED DESCRIPTION OF THE INVENTION
[0020] It has been found that a reduction in the profile of prior
art balloons using elastomeric bladders and outer reinforcing
materials can be achieved using the materials of the present
invention. The material of the present invention combines a
reinforced matrix with elastomeric properties. This unique
combination allows balloons to be formed without the need for a
separate elastomeric bladder, thus providing reduced profiles. The
present invention provides a reinforcing polymer suitable to
withstand strain in one or more directions without leaking, and is
well suited for medical devices and inflatable devices. The
material is particularly well suited for catheter balloon
applications requiring a small initial profile for entry into a
vessel. The material is preferably stronger in a longitudinal
direction as opposed to its transverse direction.
[0021] There are numerous porous membranes which would be suited to
use for an imbibed polymer. As shown in the following examples,
ePTFE has been used to demonstrate the present invention based upon
preferred properties of thinness and drapability. While reinforcing
polymers with anisotropic properties are preferred for embodiments
such as catheter balloons, an isotropic reinforcing polymer may be
desired for other imbibed material embodiments.
[0022] As shown in FIGS. 1A and 1B, the reinforcing polymer 1
comprises at least one matrix 20 with void spaces 21. The matrix
should have a top side 25 and a bottom side 26. A sealing material
3 is imbibed into the reinforcing polymer 1 to form an imbibed
reinforcing polymer 2. The sealing material 3 substantially seals
the porous matrix void spaces 21 and extends beyond the reinforcing
polymer matrix 20 to form a surface coating 4 on one side of the
reinforcing polymer 1, as shown in FIG. 2; or both sides of the
imbibed reinforcing polymer 2, as shown in FIG. 1A. The sealing
material 3 must be of a sufficient quantity not only to seal void
spaces in the reinforcing polymer, but to extend beyond the matrix
of the reinforcing polymer and form a continuous layer as a surface
coating 4. The surface coating forms a continuous layer that is
free from holes and extends beyond the matrix of the reinforcing
polymer. The reinforcing polymer may be comprised of any porous
polymer, including but not limited to fluoropolymers, polyamides,
polyesters, polycarbonates, microporous polyolefins, or UHMW
polyurethanes. The matrix can be that of a form typical of any
oriented matrix, including ePTFE.
[0023] The composite film of the present invention comprises a
porous reinforcing layer and a continuous polymer layer. The porous
reinforcing polymer layer is preferably a thin, strong porous
membrane that can be made in sheet form. The porous reinforcing
polymer can be selected from a group of polymers including, but not
limited to, olefin, PEEK, polyamide, polyurethane, polyester,
polyethylene, and polytetrafluoroethylene. In a preferred
embodiment, the porous reinforcing polymer is anisotropic such that
it is highly oriented in the one direction. An ePTFE membrane with
a matrix tensile value in one direction of greater than 690
megapascals is preferred, and greater than 960 megapascals is even
more preferred, and greater than 1,200 megapascals is most
preferred. The exceptionally high matrix tensile value of ePTFE
membrane allows the composite material to withstand very high hoop
stress in the inflated balloon configuration. In addition, the high
matrix tensile value of the ePTFE membrane makes it possible for
very thin layers to be used which reduces the deflated balloon
profile. A small profile is necessary for the balloon to be able to
be positioned in small arteries or veins or orifices. In order for
balloons to be positioned in some areas of the body, the balloon
catheter must be able to move through a small bend radius, and a
thinner walled tube is typically much more supple and capable of
bending in this manner without creasing or causing damage to the
wall of the vessel.
[0024] In another preferred embodiment, the ePTFE membrane is
relatively mechanically homogeneous. The mechanically balanced
ePTFE membrane can increase the maximum hoop stress that the
composite film made therefrom can withstand.
[0025] The continuous polymer layer of the present invention is
coated onto at least one side of the porous reinforcing polymer.
The continuous polymer layer is preferably an elastomer, such as,
but not limited to, aromatic and aliphatic polyurethanes including
copolymers, styrene block copolymers, silicones, preferably
thermoplastic silicones, fluoro-silicones, fluoroelastomers, THV
and latex. In one embodiment of the present invention, the
continuous polymer layer is coated onto only one side of the porous
reinforcing polymer. The continuous polymer layer is coated onto
both sides of the porous reinforcing polymer. In a preferred
embodiment, the continuous polymer layer is imbibed into the porous
reinforcing polymer and the imbibed polymer fills the pores of the
porous reinforcing polymer.
[0026] The continuous polymer layer can be applied to the porous
reinforcing polymer through any number of conventional methods
including, but not limited to, lamination, transfer roll coating,
wire-wound bar coating, reverse roll coating, and solution coating
or solution imbibing. In a preferred embodiment, the continuous
polymer layer is solution imbibed into the porous reinforcing
polymer. In this embodiment, the continuous polymer layer is
dissolved in a suitable solvent and coated onto and throughout the
porous reinforcing polymer using a wire-wound rod process. The
coated porous reinforcing polymer is then passed through a solvent
oven and the solvent is removed leaving a continuous polymer layer
coated onto and throughout the porous reinforcing polymer. In some
cases, such as when silicone is used as the continuous polymer
layer, the coated porous reinforcing polymer may not require the
removal of solvent. In another embodiment, the continuous polymer
layer is coated onto at least one side of the porous reinforcing
polymer and maintained in a "green" state where it can be
subsequently cured. For example, an ultraviolet light (UV) curable
urethane may be used as the continuous polymer layer and coated
onto the porous reinforcing polymer. The composite film comprising
the porous reinforcing polymer and the UV curable urethane
continuous polymer layer can then be wrapped to form at least one
layer of the balloon and subsequently exposed to UV light and
cured. A pass is a number of layers applied in a wrapping event. A
layer may comprise a single layer of composite film wrapped around
the balloon.
[0027] Some typical examples of the reinforcing polymer can
generally be found at U.S. Pat. No. 5,476,589 and U.S. patent
application Ser. No. 11/334,243. The surface coating is of a
sufficient thickness to maintain a watertight matrix when the
sealing material is stressed, inflated, or strained. The sealing
material 3 is typically an elastomeric polymer or viscous flow
material, such as an elastomer, urethane, fluoropolymer, nylon,
polyether block amide, PEBA, or other suitable material.
[0028] In one embodiment, a catheter balloon may be constructed
which changes in diameter by up to 700 percent. During the diameter
growth, the balloon wraps rotate towards the balanced force angle
of about 54.7 degrees, while the elastomer imbibed reinforcing
polymer will strain perpendicular to the wrap length up to 400-500
percent. This aspect is unique, the perpendicular strain caused by
the rotation to the balanced force angle allows higher radial
elongation of the balloon at less strain on the elastomer, as
compared to a balloon created from the elastomer alone. This
attribute of the present invention provides improved balloons with
better recovery and which are of a higher strength and higher burst
pressure than traditional balloons. Further, the diameter of the
elastomer balloon may be formed to limit the diameter growth once
the balanced forces angle is reached. This also allows for
symmetrical inflation of the balloon.
[0029] The wrap layers when configured in accordance with the
present invention form a balanced force angle which prevents the
layers from incurring transverse strain as the balloon inflates.
Transverse strain is the tendency for individual material layers to
stretch or strain perpendicular to the wrap angle. For this reason,
anisotropic materials are used which are highly oriented in the
direction of the wrap angle to allow for the strain in the
perpendicular direction. Additionally, the balloon exhibits
essentially radial symmetry upon inflation. The balloon is wrapped
by winding layers at opposing directions to one another until a
desired thickness is obtained. The balloon material passes may be
comprised of the same materials or different materials. While the
thickness of the materials may vary, for vascular use it is
advantageous to use balloon material that is less than 2
micrometers thick.
[0030] The following equation is useful for predicting the amount
of transverse strain upon the elastomer imbibed reinforcing polymer
during inflation of a balloon catheter of the present
invention:
initial width/final inflated width=1/(cos .alpha..sub.f/cos
.alpha..sub.i).sup.2.times.(tan .alpha..sub.f/tan .alpha..sub.i)
[0031] wherein .alpha. is defined as the angle between the
longitudinal axis of the balloon and the angle of the wrapped
elastomer imbibed reinforcing polymer.
[0032] In certain applications, it may be desirable that the
surface coating is formed at a thickness which allows for
controlled porosity when strained due to inflation. Such controlled
porosity allows delivery of a liquid in therapeutic quantities. The
combination of the surface coating 4 and the imbibed reinforcing
polymer 2 provides a composite film 5. The composite film 5 has a
surface coating possessing a strain capability than either the
sealing material 3 or the reinforcing polymer 1 alone. In certain
preferred embodiments it is desirable to use ePTFE as the
reinforcing polymer 1. To produce a thin strong reinforcing polymer
with a desired mass and thickness, the polymer is expanded
longitudinally and transversely prior to imbibing with a sealing
material 3. The longitudinal expansion ratio is greater than the
transverse expansion ratio. As shown in FIG. 3, the composite film
5 of the present invention is suited for use as a balloon material
layer 8. The composite film 5 can be cut or formed in longitudinal
strips or narrower pieces suitable for wrapping the composite film
around a core wire 6 or mandrel with or without a release coating
7. The angle of the wrap can vary depending upon the desired
attributes of the finished balloon. Several different areas of
differing wrap angles may exist on one balloon. In one desired
embodiment the wrap angle of the composite film is 2 and 54 degrees
with respect to the longitudinal ads of the balloon, and more
preferably less than ten degrees with respect to the longitudinal
axis of the balloon. The composite film can be wrapped at an angle
with respect to the longitudinal axis which promotes inflation to a
defined diameter, then wrapped in a reverse direction at an
opposing angle to the first pass for a plurality of passes forming
directional layers. Upon inflation, the layers of opposing
directions form a balanced force angle approaching 54 degrees
relative to each other. As shown by the cross section in FIG. 4,
the balloon material layer 8 can be wrapped in layers around the
core wire 6 (or around a release coating 7 on the wire) to form a
tubular structure suitable for use as an inflatable balloon when
sealed at the ends. The tubular structure may be subjected to heat
and inflation pressure to form a bladderless balloon with or
without the use of a mold. The balloon of the present invention
does not require a bladder, but may be constructed with a bladder
if desired. In one embodiment the balloon is comprised of at least
two helically oriented wrap layers which form an angle of
approximately 54 degrees with respect to each other upon inflation.
This angle allows the forces within the filament wound pressure
vessel to be at equilibrium. The inflatable balloon of the present
invention further exhibits radial symmetry upon inflation and
non-foreshortening. By non-foreshortening it is meant that the
length of the balloon does not change by more than ten percent
(more preferably 5 percent and even more preferably 2 percent) upon
inflation to a rated burst pressure. As shown in FIG. 5, the
composite film 5 can be used as a balloon material layer 8 and
formed into a bladderless balloon 9 suitable for use as a catheter.
Upon inflation, the inflated region 10 expands into a predetermined
shape.
[0033] FIG. 6 shows a balloon catheter device 9 with a bladderless
balloon attached to a hypotube. The bladderless balloon is attached
to the hypotube or catheter shaft via a seal or other sealing means
13. The material of the present invention may be used as the
sealing means. For example in the present invention the sealing
means holds the balloon material layer 8 in contact with the
hypotube 11 so that the balloon may be inflated without pressure
loss. The hypotube 11 has a longitudinal axis around which the
inflatable balloon is affixed. The hypotube may further comprise a
hypotube wrap layer 12 surrounding the hypotube. When the hypotube
wrap layer is present, the balloon material is affixed to the
hypotube wrap layer via a sealing means to form a seal.
[0034] FIG. 7 shows a reinforcing polymer 1 imbibed with a sealing
material 3 to form an imbibed reinforcing polymer 2 having a double
surface coating 4 layer, and forming a stretchable anisotropic
material. A single surface coating may be used when only one side
of the material wrap is desired to be coated. The surface coating
may be present on the inside surface or the outside surface of the
balloon.
[0035] In another embodiment, FIG. 8 shows a cross section of a
bladderless balloon having a surface coating of a thickness
allowing for controlled porosity when strained due to inflation.
Controlled porosity allows delivery of a liquid 15 from one side of
the imbibed reinforcing polymer to the other side. The controlled
porosity is a tortuous path, thereby allowing the therapeutic
liquid to weep, (form droplets on the surface of the balloon). In
another embodiment, the bladderless balloon having a surface
coating of a thickness allowing for controlled porosity, weeps only
at high pressure. As shown in FIG. 8, the imbibed reinforcing
polymer 2 has at least one surface coating 4 formed by the sealing
material 3. The imbibed reinforcing polymer is formed into a
bladderless balloon 9 having stretchable anisotropic material 14
properties. When the bladderless balloon is inflated by a fluid,
small openings occur in the surface coating which allow movement of
the fluid from the interior side of the balloon through the imbibed
reinforcing polymer 2 to the outside of the balloon. Delivery of
therapeutic liquid agents may be facilitated using a bladderless
balloon comprised of an imbibed reinforcing polymer with a
controlled porosity. This controlled porosity is able to withstand
pressures greater than 10 p.s.i., before allowing fluid movement
from the interior to the exterior side of the balloon.
[0036] FIG. 9 shows that the bladderless balloon may be constructed
to include at least one non-distending layer 7 to provide a desired
shape to the bladderless balloon or to provide a continuous
integrated seal on an inflatable balloon. The continuous integrated
seal may be formed by using or providing a first balloon material
layer 8 which is configured to form a desired balloon shape. The
sealing material may be a balloon material layer 8, as such, an
ePTFE reinforcing polymer imbibed with sealing material 3. The
balloon shape is then wrapped with a wrap layer around said first
balloon material layer so that the angle of the wrap changes to
wrap at least one wrap layer at an angle sufficient to create seal
over the first balloon material layer upon inflation. A second
balloon material layer may then be wrapped around the seal to
increase the bonding surface area of the seal if desired. In this
manner the seal is located between two balloon materials to provide
a gentle failure mode on a bladderless balloon. The material
composite may be used to comprise the non-distensible regions. As
shown in FIG. 9, the core wire 6 may be provided with a release
coating 25. The release coating may be of a desired thickness to
provide a desired inner diameter on the finished balloon. The
release coating has a balloon material layer wrapped and set around
the core wire 6 to provide a bladderless balloon.
[0037] FIG. 10 provides a cross section of a non-distensible seal
on a bladderless balloon. The non-distensible seal is integrated as
a wrap layer on top of the balloon itself. It may be wrapped at the
same time as the bladderless balloon by adjusting the wrap angle of
the composite film wrap. The balloon material layer 8 is then
wrapped with a non-distending layer 7 in desired areas to provide
the bladderless balloon with non-distending regions, as shown in
FIG. 9. The non-distending regions should be comprised of balanced
multiple wrap layers oriented so that the number of passes of wrap
lying in one direction is equal to the number of passes of wrap in
an opposite overlying direction.
[0038] The following examples are offered for illustrative purposes
only and are not intended to limit the teaching of the present
invention.
EXAMPLES
Example 1
Composite Film
[0039] The ePTFE reinforcing polymer 1 used to make the composite
film was made in accordance with the teachings found in U.S. Pat.
No. 5,476,589 to Bacino, incorporated by reference herewith.
Specifically, the ePTFE reinforcing polymer was longitudinally
expanded to a ratio of 55 to 1 and transversely expanded
approximately 2.25 to 1, to produce a thin strong reinforcing
polymer with a mass of approximately 3.5 g/m.sup.2 and a thickness
of approximately 6.5 micrometers.
[0040] The composite film 3 was made by using a wire-wound rod
coating process whereby a solution of Tecothane TT-1085A
polyurethane (Thermedics, Inc., Wobum, Mass.) and tetrahydrofuran
(THF) was coated onto an ePTFE reinforcing polymer. A 3-8 percent
by weight solution of Tecothane TT-1085A polyurethane in THF was
coated onto the ePTFE reinforcing polymer to produce a composite
film with approximately equal amounts of Tecothane TT-1085A
polyurethane as depicted in FIG. 1B on either side and throughout
the ePTFE reinforcing polymer and a total polymer weight
application of approximately 40-60 percent of the total final
composite film weight.
Example 2
Bladderless Balloon
[0041] The bladderless balloon of the present invention was made by
wrapping a composite film of Techothane TT-1085A polyurethane
(Thermedics, Inc., Wobum, Mass.), and ePTFE reinforcing polymer
over a FEP coated silver-plated copper core wire (Putnam Plastics
LLC, Dayville, Conn.). The wrapped core wile was heat treated and
the center wire and FEP coating were subsequently removed to
provide a hollow composite balloon tube.
[0042] The core wire was a 0.2 mm diameter silver-plated copper
wire with a fluoroethylene-propylene (FEP) 5100 coating that
resulted in a final wire diameter of 0.394 mm. The ePTFE
reinforcing polymer used to make the composite film is described in
Example 1. Specifically, the ePTFE reinforcing polymer was
longitudinally expanded to a ratio of 55 to 1 and transversely
expanded approximately 2.25 to 1, to produce a thin strong
reinforcing polymer with a mass of approximately 3.5 g/m.sup.2 and
a thickness of approximately 6.5 micrometers.
[0043] The composite film was made by using a wire-wound rod
coating process whereby a solution of Tecothane TT-1085A
polyurethane and tetrahydrofuran (THF) was coated onto an ePTFE
reinforcing polymer. A 3-8 percent by weight solution of Tecothane
TT-1085A polyurethane in THF was coated onto the ePTFE reinforcing
polymer to produce a composite film with approximately equal
amounts of TT-1085A polyurethane on either side and throughout the
ePTFE reinforcing polymer and a total polymer weight application of
approximately 40-60 percent of the total final composite film
weight.
[0044] The composite film was slit to 5 mm wide and helically
wrapped around the 30.5 cm long core wire at a 4 to 5 degree angle
from the longitudinal as of the wire. The wrapped core wire was
heated for approximately 5 to 30 seconds at 180.degree. C. after
wrapping. The core wire was then wrapped with the composite film in
the opposite direction at a 4 to 5 degree angle from the
longitudinal ads of the wire and subsequently heated for
approximately 5 to 30 seconds at 180.degree. C. The process of
wrapping the core wire in opposite directions and heating after
each pass was repeated until a total of four passes of wrapping was
complete. The wrapped core wire was wrapped around a pin frame with
approximately 30 cm spaces between pins and approximately 180
degrees of wrap around each pin and tied at the ends before being
placed into an oven and heated for approximately 30 minutes at
150.degree. C.
[0045] The core wire and the FEP coating over the core wire were
removed from the composite balloon over wire construction. An
approximately 2.54 cm long section of the composite hollow balloon
tube was removed from either end of a 30.5 cm long section of the
balloon over wire construction. The exposed ends of the wire were
clamped with hemostats and pulled by hand until the wire had been
stretched approximately 5 cm, at which point it was removed from
the center of the tube. The plastic FEP coating was removed in a
similar fashion, but was stretched approximately 50 cm before it
was removed from the balloon. A composite hollow balloon tube was
produced with a first layer wrapping material at a low (4 to 5
degree) angle of wrap.
[0046] The 2.85 mm inflated diameter by 27 mm long balloon was
mounted to a 0.36 mm diameter stainless steel hypotube (Creganna
Medical Devices, Parkmore West Galway, Ireland) that had been
helically wrapped with approximately three layers of expanded PTFE
reinforcing polymer and EFEP fluoroplastic composite with the EFEP
layer facing the stainless steel tube. The balloon was attached and
sealed to the catheter shaft by wrapping an approximately 5 mm wide
ePTFE/eFEP film circumferentially around the balloon approximately
five times. One band was wrapped on each end of the balloon and was
centered over the end of the balloon and the catheter such that it
made a seal by contacting both the hypotube shaft and the balloon
as depicted in FIG. 6.
Example 3
Bladderless Balloon with Heat Inflation Technique
[0047] The bladderless balloon of the present invention was made by
wrapping a composite film of Techothane TT-1085A polyurethane
(Thermedics, Inc., Wobum, Mass.), and ePTFE reinforcing polymer
over a FEP coated silver-plated copper core wire (Putnam Plastics
LLC, Dayville, Conn.). The wrapped core wire was heat treated and
the center wire and FEP coating were subsequently removed to
provide a hollow composite balloon tube.
[0048] The core wire was a 0.2 mm diameter silver-plated copper
wire with a fluoroethylene-propylene (FEP) 5100, coating that
resulted in a final wire diameter of 0.394 mm. The ePTFE
reinforcing polymer was longitudinally expanded to a ratio of 55 to
1 and transversely expanded approximately 2.25 to 1, to produce a
thin strong reinforcing polymer with a mass of approximately 3.5
g/m.sup.2 and a thickness of approximately 6.5 micrometers.
[0049] The composite film was made by using a wire-wound rod
coating process whereby a solution of Tecothane TT-1085A
polyurethane and tetrahydrofuran (THF) was coated onto an ePTFE
reinforcing polymer. A 3-8 percent by weight solution of Tecothane
TT-1085A polyurethane in THF was coated onto the ePTFE reinforcing
polymer to produce a composite film with approximately equal
amounts of Tecothane TT-1085A polyurethane on either side and
throughout the ePTFE reinforcing polymer and a total polymer weight
application of approximately 40-60 percent of the total final
composite film weight.
[0050] The composite film was slit to 5 mm wide and helically
wrapped around the 30.5 cm long core wire at a 4 to 5 degree angle
from the longitudinal ads of the wire. The wrapped core wire was
heated for approximately 5 to 30 seconds at 180.degree. C. after
wrapping. The core wire was then wrapped with the composite film in
the opposite direction at a 4 to 5 degree angle from the
longitudinal as of the wire and subsequently heated for
approximately 5 to 30 seconds at 180.degree. C. The process of
wrapping the core wire in opposite directions and heating after
each pass was repeated until a total of four passes of wrapping was
complete. The wrapped core wire was wrapped around a pin frame with
approximately 30 cm spaces between pins and approximately 180
degrees of wrap around each pin and tied at the ends before being
placed into an oven and heated for approximately 30 minutes at
150.degree. C.
[0051] The core wire and the FEP coating over the core wire were
removed from the composite balloon over wire construction. An
approximately 2.54 cm long section of the composite hollow balloon
tube was removed from either end of a 30.5 cm long section of the
balloon over wire construction. The exposed ends of the wire were
clamped with hemostats and pulled by hand until the wire had been
stretched approximately 5 cm, at which point it was removed from
the center of the tube. The plastic FEP coating was removed in a
similar fashion, but was stretched approximately 50 cm before it
was removed from the balloon. A composite hollow balloon tube was
produced with a first layer wrapping material at a low (4 to 5
degree) angle of wrap.
[0052] A 15.25 cm long section of the composite hollow balloon tube
was tied into a knot and damped with a hemostat on one end. The
opposite end was slipped through a Qosina male touhy borst with
spin lock fitting (#80343, Qosina Corporation, Edgewood, N.Y.), and
a Monoject blunt needle with Aluminum luer lock hub (model
#8881-202389, Sherwood Medical, St. Louis, Mo.) was inserted
approximately 2.0 cm into the balloon. The hemostatic valve was
tightened to seal the balloon, and was then attached to a Balloon
Development Station Model 210A (Beahm Designs, Inc., Campbell,
Calif.). The nozzle airflow was set to 25-30 units and the
temperature was set to 140.degree. C., air pressure to 2.58
atmospheres. The air pressure was turned on, the center 40 mm long
region to be inflated was subjected to heat for about 2-3 minutes
resulting in a balloon with a diameter of 2.85 mm. The diameter was
checked with a Mitutoyo Laser Scan Micrometer Model LSM-3100
(Mitutoyo America Corp, Aurora, Ill.) while in the inflated state.
The resulting balloon had a diameter of 2.85 mm and an inflated
length of 27 mm.
[0053] Using a Monoject blunt needle with Aluminum luer lock hub
(model #8881-202389, Sherwood Medical, St. Louis, Mo.) dispensing
needle, the balloon was subjected to an internal pressure of 5.44
atmospheres at room temperature for approximately 1 hour.
[0054] The 2.85 mm inflated diameter by 27 mm long balloon was
mounted to a 0.36 mm diameter stainless steel hypotube (Creganna
Medical Devices, Parkmore West Galway, Ireland) that had been
helically wrapped with approximately three layers of expanded PTFE
reinforcing polymer and EFEP fluoroplastic composite with the EFEP
layer facing the stainless steel tube. The balloon was attached and
sealed to the catheter shaft by wrapping an approximately 5 mm wide
ePTFE/eFEP film circumferentially around the balloon approximately
five times. One band was wrapped on each end of the balloon and was
centered over the end of the balloon and the catheter such that it
made a seal by contacting both the hypotube shaft and the
balloon.
Example 4
Material Properties
[0055] All of the experimental runs were performed using Mayer Bar
coating technology and direct solution feed to the coating
surface.
[0056] The Mayer Bar is simply a metal bar with wire windings.
[0057] Bars with windings of different wire sizes are used to
achieve the desired thickness in coating. The Mayer Bar is used to
apply the wet coating to the ePTFE membrane. The coating dries with
the aid of an inline oven. The finished coated membrane receives a
second coat directly to the membrane surface. This process provides
an even coating and offers flexibilty in the laydown design.
Example 5
[0058] The Tecothane 1085 (TT1085) elastomer, used in the coating,
is readily solvated in Tetrahydofuran (THF). THF is characterized
by a low vapor pressure, and as expected, a fast evaporation rate.
Using this material the following results were obtained:
Test Samples:
TABLE-US-00001 [0059] Sample 1 Single Sided Coat "2 Passes" Sample
2 Single Sided Coat "4 Passes" Sample 3 Double Sided Coat "2
Passes" Sample 4 Double Sided Coat "4 Passes"
Results: Gross Testing @Ambient Temperatures
[0060] Sample 1: Inflated to 30 atm--no weeping for two minutes.
[0061] Sample 2: Inflated to 30 atm--no weeping for three minutes.
[0062] Sample 3: Inflated to 30 atm--no weeping observed until
burst at 3 minutes. [0063] Sample 4: Inflated to 30 atm--no weeping
observed until burst at 7 minutes.
Multiple Inflation Testing.
[0064] The following procedure was used for this test. Each unit
was preconditioned at 37.degree. C. for 2 minutes. At 37.degree.
C., nine inflations were made to 18 atm and held for 30 seconds. On
the 10.sup.th inflation, the unit was removed from the bath, wiped
off, and inspected for weeping. [0065] Sample 1: Weeping observed
on the 10.sup.th inflation. [0066] Sample 2: Weeping observed on
the 10.sup.th inflation. [0067] Sample 3: No weeping observed on
10.sup.th inflation. Balloon was pressurized for 4 minutes. [0068]
Sample 4: No weeping observed on 10.sup.th inflation. Balloon was
pressurized for 45 minutes.
[0069] While particular embodiments of the present invention have
been illustrated and described herein, the present invention should
not be limited to such illustrations and descriptions. It should be
apparent that changes and modifications may be incorporated and
embodied as part of the present invention within the scope of the
following claims.
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