U.S. patent application number 10/357665 was filed with the patent office on 2003-07-24 for angioplasty balloon with thin-walled taper and method of making the same.
Invention is credited to Lee, Jeong S..
Application Number | 20030139762 10/357665 |
Document ID | / |
Family ID | 23866177 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030139762 |
Kind Code |
A1 |
Lee, Jeong S. |
July 24, 2003 |
Angioplasty balloon with thin-walled taper and method of making the
same
Abstract
An angioplasty balloon and method of manufacture are provided.
The balloon has a working length and a taper each having a
substantially equivalent thickness. This allows the balloon to be
steered easily through vasculature to the site of a stenosis prior
to inflation during an angioplasty procedure. The taper thickness
in particular is achieved through use of a specially designed
multi-tubular slug which is molded to form the angioplasty balloon
of the present invention.
Inventors: |
Lee, Jeong S.; (Diamond Bar,
CA) |
Correspondence
Address: |
James C. Scheller, Jr.
BLAKELY, SOKOLOFF, TAYLOR & ZAFMAN LLP
Seventh Floor
12400 Wilshire Boulevard
Los Angeles
CA
90025-1026
US
|
Family ID: |
23866177 |
Appl. No.: |
10/357665 |
Filed: |
February 3, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10357665 |
Feb 3, 2003 |
|
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09470075 |
Dec 22, 1999 |
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Current U.S.
Class: |
606/194 ;
156/244.14 |
Current CPC
Class: |
B29C 49/02 20130101;
B29C 2949/08 20220501; B29K 2105/258 20130101; A61M 25/1029
20130101; B29L 2031/7542 20130101; B29C 67/0014 20130101; B29L
2022/025 20130101 |
Class at
Publication: |
606/194 ;
156/244.14 |
International
Class: |
A61M 029/00 |
Claims
1. A slug for manufacturing an angioplasty balloon, said slug
comprising: a shortened outer tube and: an inner tube, said inner
tube being longer in length than said shortened outer tube, said
shortened outer tube circumferentially surrounding said inner
tube.
2. The slug of claim 1 wherein said shortened outer tube is fused
to said inner tube.
3. The slug of claim 1 wherein said outer tube has an outer tube
wall thickness greater than an inner tube wall thickness of said
inner tube.
4. The slug of claim 1 wherein said shortened outer tube has a
constant outer tube inner diameter cooperating with a constant
inner tube outer diameter.
5. The slug of claim 1 wherein said shortened outer tube has a
variable outer tube inner diameter cooperating with a variable
inner tube outer diameter.
6. The slug of claim 1 wherein said shortened outer tube has an
end, said end being pre-necked.
7. The slug of claim 1 wherein said slug is comprised of a
polymeric material selected from the group consisting of:
polyethylene terephthalate, a polyetherblockamide, a polyamide, a
thermoplastic copolyester, a polyolefin, and a polyether-ester
block copolymer.
8. The slug of claim 1 wherein one of said shortened outer tube and
said inner tube is comprised of tubing material, said tubing
material being a co-extruded polymer of two or more layers.
9. The slug of claim 1 wherein said slug further comprises an
additional tube, said additional tube circumferentially surrounding
said inner tube.
10. A method of forming an angioplasty balloon catheter from a
slug, said method comprising: surrounding an inner tube with a
shortened outer tube to form said slug; placing said slug within a
mold, said mold defining a desired angioplasty balloon profile; and
molding said slug with said mold to form an angioplasty balloon
catheter having a working length extending into a taper which
further extends into a shaft.
11. The method of claim 10 further comprising extruding said inner
tube and said shortened outer tube in a manner giving randomized
molecular alignment to any polymer comprising said inner tube and
said shortened outer tube prior to said surrounding.
12. The method of claim 10 further comprising pre-necking an outer
end of said shortened outer tube prior to said molding.
13. The method of claim 10 further comprising adding an additional
tube circumferentially around said inner tube prior to said
molding.
14. The method of claim 10 wherein said molding further comprises:
heating said slug; and pressurizing said slug to form an
angioplasty balloon within said mold, said angioplasty balloon
comprising said working length and said taper.
15. The method of claim 14 wherein said heating further comprises
providing a temperature above a glass transition temperature of any
polymer comprising said slug.
16. The method of claim 14 wherein said pressurizing further
comprises providing a pressure of at least 300 p.s.i. within said
mold.
17. The method of claim 10 further comprising fusing said shortened
outer tube to said inner tube prior to said molding.
18. The method of claim 17 wherein said fusing comprises heating
said slug above a glass transition temperature of any polymer
comprising said slug.
19. The method of claim 10 wherein said working length has a
working length thickness, said taper has a taper thickness, and
said shaft has a shaft thickness, said working length thickness,
said taper thickness, and said shaft thickness being substantially
equivalent.
20. The method of claim 10 wherein said shortened outer tube
further comprises an outer end, said molding transforming said
shortened outer tube into said working length and said molding
creating said taper from said outer end and said inner tube.
21. An angioplasty balloon comprising: a working length having a
working length wall thickness; and a taper extending from said
working length and having a taper wall thickness, said taper wall
thickness and said working length wall thickness being
substantially equivalent.
22. The angioplasty balloon of claim 21 further comprising a shaft
extending from said taper and having a shaft wall thickness, said
shaft wall thickness being substantially equivalent to said taper
wall thickness and said working length wall thickness.
23. The angioplasty balloon catheter of claim 22 wherein said
working length further comprises an inner diameter being
substantially constant throughout said working length, said shaft
further comprises an inner shaft diameter being substantially
constant throughout said shaft, and said taper further comprises an
inner taper diameter which diminishes throughout said taper from
said working length to said shaft, providing a smooth transition
there between.
24. The angioplasty balloon of claim 1 further comprising a
two-layer composite capable of withstanding pressures higher than
conventionally possible, said two-layer composite comprising said
working length.
25. The angioplasty balloon of claim 24 wherein said two-layer
composite further comprises at least a portion of said taper.
26. The angioplasty balloon of claim 24 or claim 25 wherein said
two-layer composite is a polyetherblockamide-polyamide
composite.
27. The angioplasty balloon of claim 22 wherein said shaft is
comprised of a polyamide.
28. The angioplasty balloon of claim 21 wherein said taper and said
working length comprise an angioplasty balloon, said angioplasty
balloon being between 10 mm and 40 mm in length.
29. The angioplasty balloon of claim 22 wherein said working length
wall thickness, said taper wall thickness, and said shaft wall
thickness are between 0.010 mm and 0.051 mm.
30. The angioplasty balloon of claim 22 wherein said working length
further comprises an outer diameter, said shaft further comprises
an outer shaft diameter, and said taper further comprises an outer
taper diameter, said outer diameter, said outer shaft diameter, and
said outer taper diameter being between 0.60 mm and 15.0 mm.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates generally to dilation catheters. More
particularly, the invention relates to intravascular angioplasty
catheter balloons and a method of manufacturing the same.
[0003] 2. Description of the Related Art
[0004] Angioplasty is a procedure by which stenotic lesions
(atheromatous deposits), found in cases of atherosclerosis. During
angioplasty, a guidewire is inserted into the cardiovascular
system, generally via the femoral artery under local anesthesia.
The guidewire is advanced through the patient's vasculature to the
site of the stenosis (stenotic lesion). Placement of the guidewire
may be aided by way of fluoroscopic observation. A dilatation
catheter, having a guidewire lumen and distensible balloon portion,
is then advanced through the vasculature until the balloon portion,
at the distal end of the catheter, traverses or crosses a stenotic
lesion. The artery is narrowed in the area of the stenotic lesion
due to the atheromatous deposits occupying arterial space at the
walls of the artery. Once placed, the balloon portion of the
catheter is inflated, generally with a fluid, to compress the
atheromatous deposits against the walls of the artery. This
compression dilates the lumen of the artery leaving an unblocked
arterial passage once the guidewire and catheter are removed.
[0005] Looking back to where the uninflated balloon encounters the
stenosis, it must first cross at least a portion thereof in order
to reach its distal-most destination. Therefore, a flexible, low
profile balloon is preferable. In particular, the ends of the
uninflated balloon should taper smoothly and lay low so that the
balloon can be threaded into tight passages. It is preferable that
the thickness of the balloon material be substantially constant
from a working length throughout each taper. In the present
context, a thick wall is at least approximately 0.002" in thickness
while a thin wall is approximately 0.001" in thickness.
[0006] Unfortunately, current production methods yield a balloon
with stiff and bulky tapers. These limitations are related to the
behavior of the balloon material during manufacture, where a piece
of polymer tubing is stretched to make the balloon. The balloon is
made ("blown") by placing a segment of polymeric tubing in a mold,
heating it to a near-molten state, and pressurizing the tubing
until it fills the mold. The, tubing within the mold forms the
balloon. The mold is shaped such that the balloon is comprised of a
working length with a taper at each end thereof. Each taper joins
an unexpanded segment of tubing outside of the mold, referred to
here as a shaft. Because the tapers expand less than the working
length, they remain stiffer and bulkier. A thin-walled taper would
be more desirable.
[0007] One approach to thinning the wall of the taper is a process
called "pre-necking" in which the segment of tubing that will
become the taper is first softened by heating and then subjected to
a force which forms a narrowed segment in the tubing, referred to
here as a neck. The objective of pre-necking is to form the taper
from this neck. As the balloon is blown, the neck expands to form a
taper having thinner walls than a taper blown from un-necked
tubing. The thin taper terminates at a thin shaft. However, the
problem of thick, stiff tapers still remains to a certain extent
because the pre-necking is performed in a solid or semi-molten
state in which the strain applied to the tubing induces
crystallization. In effect, the molecular strands of the polymer
become aligned parallel to the load inducing the strain. Once
aligned in this manner, the polymer resists further distension.
Thus, due to pre-necking, we have exchanged a thicker taper for a
somewhat thinner taper which nonetheless remains less expansive
than the reminder of the balloon. The remainder of the balloon,
which is intended for contacting the wall of a body lumen such as
during an angioplasty, is often referred to as the working distance
or the working length. In the case of pre-necked balloons we end up
with a thin taper which is less expansive than the working
length.
[0008] What is needed, therefore, is an angioplasty balloon having
a thin taper terminating at a thin shaft. It is desirable that the
thin taper have a wall of substantially equivalent thickness to a
wall of the working length.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide an
angioplasty balloon having a taper thickness substantially
equivalent to a working length thickness.
[0010] It is an object of the present invention to provide an
angioplasty balloon having a thin shaft.
[0011] It is an object of the present invention to provide an
angioplasty balloon having a wall thickness no greater than 0.002",
and in one embodiment between 0.0005" and 0.002".
[0012] It is an object of the present invention to provide a slug
capable of being molded into an angioplasty balloon having a taper
thickness substantially equivalent to a working length
thickness.
[0013] It is an object of the present invention to provide a slug
comprising a polymeric inner tube within a shortened polymeric
outer tube.
[0014] It is an object of the present invention to provide a method
of manufacturing an angioplasty balloon having a taper thickness
substantially equivalent to a working length thickness.
[0015] In accordance with these objectives an angioplasty balloon
40 is provided having a taper wall thickness 76 substantially
equivalent to a working length wall thickness 60. The angioplasty
balloon 40 is manufactured from a slug 100 having an inner tube 106
within a shortened outer tube 102. The shortened outer tube 102 is
fused to the inner tube 106 within a mold until an angioplasty
balloon 40 has formed. The working length 44 of the angioplasty
balloon 40 has formed from the shortened outer tube 102 while the
inner tube 106 forms a taper (48, 50) at each end of the working
length 44. Each taper (48, 50) terminates in a shaft (42, 46). The
working length 44, taper (48, 50), and shaft (42, 46) each have
substantially equivalent wall thicknesses (60, 66, 76).
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a perspective partially sectioned view of the
angioplasty balloon of the present invention.
[0017] FIG. 2 is a side sectional view of the slug of the present
invention.
[0018] FIG. 3 is a side sectional view of the angioplasty balloon
of the present invention.
[0019] FIG. 4 is a flow chart of a method of manufacturing the
angioplasty balloon of the present invention.
DETAILED DESCRIPTION
[0020] Referring to FIG. 1, the angioplasty balloon 40 of the
present invention is shown partially sectioned. The angioplasty
balloon 40 has a working length 44 which extends proximally into a
proximal taper 48 and proximal shaft 42. The working length 44
extends distally into a distal taper 50 and distal shaft 46. A
balloon lumen 52 is surrounded by the angioplasty balloon 40. The
working length 44 has an inner diameter 58, an outer diameter 56,
and a working length wall thickness 60 there between. The diameters
(58, 56) are between 1.5 and 15.0 mm and fairly constant throughout
the working length 44 of the angioplasty balloon 40. The working
length wall thickness 60 is between 0.010 mm and 0.045 mm and
fairly constant throughout the working length 44 of the angioplasty
balloon 40.
[0021] Continuing with reference to FIG. 1, the distal shaft 46 has
an inner shaft diameter 64, an outer shaft diameter 62, and a shaft
wall thickness 66 there between. The diameters (64, 62) are between
0.600 mm and 0.720 mm and fairly constant throughout the distal
shaft 46 of the angioplasty balloon 40. The shaft wall thickness 66
is between 0.010 mm and 0.051 mm and fairly constant throughout the
distal shaft 46 of the angioplasty balloon 40. The length of the
angioplasty balloon 40, between the distal shaft 46 and the
proximal shaft 42, generally ranges from 10 mm to 40 mm. However,
this is merely a matter of design choice. The proximal shaft 42 is
fairly dimensionally equivalent to the distal shaft 46. However,
the proximal shaft 42 is adaptable to communicating with an
external supply of fluid pressure and/or delivering such to the
angioplasty balloon 40.
[0022] The working length 44 adjoins the distal shaft 46 by way of
a distal taper 50. The distal taper 50 has an inner taper diameter
80 and an outer taper diameter 78 which diminish from the working
length 44 to the distal shaft 46 providing a smooth transition
there between. A taper wall thickness 76 is found between the inner
taper diameter 80 and the outer taper diameter 78. The proximal
taper 48 is comparable to the distal taper 50 in dimensions and
construction.
[0023] As configured for angioplasty, the angioplasty balloon 40 is
affixed to the distal portion of a catheter (not shown). The
balloon lumen 52 communicates with an inflation lumen of the
catheter to provide inflation, fluid or otherwise, to the
angioplasty balloon 40. When pressurized, tapers (48, 50) and the
working length 44 expand until the full diameters (56, 58, 62, 64,
78, 80) are achieved. However, when not pressurized, tapers (48,
50) and the working length 44 lie flattened or folded. When the
working length 44 is collapsed to its lowest profile, the tapers
(48, 50) are able to collapse to a comparably low profile.
Additionally, the flattened tapers (48, 50) have flexibility
comparable to that of the flattened working length 44. These
characteristics are advantageous because they lessen the resistance
encountered by the uninflated balloon as it is forced through a
tight stenosis or sharp curves of vasculature. As a result, the
angioplasty balloon 40 can be maneuvered into more difficult
stenoses and is less likely to traumatize the artery.
[0024] Referring to FIG. 2, a cross sectional view of a slug 100 is
shown. The slug 100 is made of a shortened outer tube 102
surrounding an inner tube 106 and being in communication therewith.
The inner tube 106 has been inserted into the shortened outer tube
102. The shortened outer tube 102 has an outer proximal end 103 and
an outer distal end 104. The shortened outer tube 102 has an outer
tube outer diameter 110, an outer tube inner diameter 112 and an
outer tube wall thickness 114 there between. The shortened outer
tube 102 is of a length less than that of the inner tube 106. The
inner tube 106 has an inner proximal end 108 and an inner distal
end 109. The inner tube 106 has an inner tube outer diameter 112,
an inner tube inner diameter 118 and an inner tube wall thickness
120 there between.
[0025] Referring to FIGS. 2-4, a cross sectional view of an
angioplasty balloon 40 formed from the slug 100 is shown. The slug
100 has been placed within a mold (not shown) which defines a
desired angioplasty balloon 40 profile. The slug 100 has been
heated and pressurized, whereupon the shortened outer tube 102 and
the inner tube 106 have filled the mold. During heating, the
shortened outer tube 102 and the inner tube 106 have fused. During
pressurization, the proximal taper 48 and the distal taper 50 have
been formed by expansion of the inner tube 106 and the shortened
outer tube 102 within the mold (not shown). Once the tapers (48,
50) have been formed in this manner, the angioplasty balloon 40 has
been formed. In particular, the shortened outer tube 102 has formed
the working length 44. The inner tube 106 and the outer distal end
104 have formed the distal taper 50. The inner tube 106 and the
outer proximal end 103 have formed the proximal taper 48.
[0026] Continuing with reference to FIGS. 2-4, the tapers (48, 50)
form easily as the angioplasty balloon 40 easily expands within the
mold due to the configuration of the shortened outer tube 102 and
the inner tube 106. This ease of expansion is due to the
substantial disorientation of the molecular structure of the
polymer compound of the tubes (102, 106). The tubes (102, 106) are
extruded at molten temperatures hot enough to randomize the
molecular alignment of the polymer. Generally, this randomization
of molecular structure is followed by pre-necking which eliminates
the randomization to a degree. However, the present invention
provides a slug 100 which allows the reduction or complete
elimination of pre-necking. With a reduction or elimination of
pre-necking, little or no orientation is imposed upon the polymer
and the tubes (102, 106) retain most, if not all, of their
distensibility.
[0027] As a result of the configuration of the slug 100, less
overall tube material is provided to the tapers (48, 50) than to
the working length 44. This corresponds with the fact that the
tapers (48, 50) occupy less overall space than the working length
44 in a formed angioplasty balloon 40. Thus, in the formed balloon
40, as the diameters (78, 80) of the tapers (48, 50) diminish from
the working length 44 to the shafts (42, 46), the taper wall
thickness 76 does not increase appreciably. Low profile and
flexibility are achieved. This may be further enhanced by utilizing
an inner tube wall thickness 120 less than the outer tube wall
thickness 114. Additionally, having a larger diameter shortened
outer tube 102 furthers a larger diameter working length 44, while
a smaller diameter inner tube 106 furthers smaller diameter shafts
(42, 46). These features contribute to low profile and flexibility
of the angioplasty balloon 40.
[0028] The shortened outer tube 102 may be fused to the inner tube
106 before or during the formation of the angioplasty balloon 40
within the mold. Fusion prior to molding of the angioplasty balloon
40 may be achieved by various combinations of heat and pressure.
Preferably, the temperature during fusion will exceed the glass
transition temperature of the polymer. Above the glass transition
temperature, the tubing is easily deformed. Below the glass
transition temperature, the polymer resists deformation.
Additionally, the tubes (102, 106) should be made of compatible
materials, especially if fusion is to occur prior to the
angioplasty balloon 40 being blown.
[0029] Generally, the tubes (102, 106) will be made from the same
or compatible polymers. For example, both may be made of a
polyetherblockamide material, commercially available as PEBAX.RTM.
7033 (PEBAX) or a like material, producing an angioplasty balloon
40 of uniform composition. Alternatively, the shortened outer tube
102 may be made of PEBAX while the inner tube 106 is made of a
polyamide such as nylon. This will produce a two layer composite
working length 44 having nylon shafts (42, 46). The use of a nylon
inner tube 106 to produce a two layer composite working length 44
may provide an angioplasty balloon 40 capable of withstanding
pressures higher than conventionally possible. If PEBAX-Nylon
compositions are utilized where the tubes (102, 106) are fused
while the angioplasty balloon 40 is blown, a high temperature
(about 235.degree. F.) and high pressure (300 p.s.i. or more) will
be required.
[0030] Other combinations of materials include, for example,
polyethylene terephthalate (PET) and a thermoplastic copolyester,
commercially available as Hytrel.RTM. (a polyether-ester block
copolymer) or Amitel.RTM.. Thermoplastic copolyesters can be
difficult to blow into a balloon shape because they lose their
strength when heated. However, a composite of thermoplastic
copolyester with PET (which readily forms a balloon shape) can
produce a two layered angioplasty balloon 40. Alternatively, the
tubes (102, 106) may be made of identical or different
polyolefins.
[0031] In addition to the above variations, the slug 100 may be
comprised of more than two tubes assembled together to achieve
different shaft 42 or working length 44 properties. One of the
tubes (102, 106, or another) may be a co-extruded tube of two or
more layers. The slug 100 may or may not be pre-necked at its outer
proximal end 103, its outer distal end 104, or both. Diameters (56,
58, 62, 64) may be constant or variable while the taper diameters
(78, 80) may have identical or different characteristics as between
the proximal taper 48 and the distal taper 50.
* * * * *