U.S. patent application number 10/969526 was filed with the patent office on 2005-05-26 for surgical balloon having varying wall thickness.
Invention is credited to Dion, Dorothy, Nohilly, Martin.
Application Number | 20050113857 10/969526 |
Document ID | / |
Family ID | 32393114 |
Filed Date | 2005-05-26 |
United States Patent
Application |
20050113857 |
Kind Code |
A1 |
Nohilly, Martin ; et
al. |
May 26, 2005 |
Surgical balloon having varying wall thickness
Abstract
A surgical balloon is provided for insertion into a uterus that
includes a substantially continuous outer wall defining an exterior
surface of the balloon on a first side and an interior hollow of
the balloon on a second side, with the outer wall being formed from
a stretchable elastic material and being stretchable by pressure
within the inner hollow between a collapsed state and an expanded
state. The substantially continuous outer wall has a base portion
for coupling with shaft, an intermediate portion adjacent the base
portion and an end portion at a distal end of the balloon and
adjacent the intermediate portion. The base portion has a first
primary wall thickness, the intermediate portion has a second
primary wall thickness, and the end portion has a third primary
wall thickness.
Inventors: |
Nohilly, Martin; (Murray
Hill, NJ) ; Dion, Dorothy; (West Orange, NJ) |
Correspondence
Address: |
PHILIP S. JOHNSON
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
32393114 |
Appl. No.: |
10/969526 |
Filed: |
October 20, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10969526 |
Oct 20, 2004 |
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10326044 |
Dec 20, 2002 |
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10326044 |
Dec 20, 2002 |
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09749077 |
Dec 27, 2000 |
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6607545 |
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Current U.S.
Class: |
606/193 |
Current CPC
Class: |
A61B 18/04 20130101;
A61B 2017/22051 20130101; A61M 25/1002 20130101; A61M 29/02
20130101; A61B 2017/4216 20130101; A61M 2025/1059 20130101; A61B
2018/046 20130101; A61M 2210/1433 20130101 |
Class at
Publication: |
606/193 |
International
Class: |
A61M 029/00 |
Claims
1-10. (canceled)
11. A surgical balloon for insertion into a uterus, comprising: a
substantially continuous outer wall defining an exterior surface of
the balloon on a first side and an interior hollow of the balloon
on a second side, the outer wall being formed from a stretchable
elastic material and being stretchable by pressure within the inner
hollow between a collapsed state and an expanded state; the
substantially continuous outer wall having a base portion for
coupling with shaft, an intermediate portion adjacent the base
portion and an end portion at a distal end of the balloon and
adjacent the intermediate portion, wherein, when the balloon is in
the collapsed state, the base portion has a first primary wall
thickness, the intermediate portion has a second primary wall
thickness, and the end portion has a third primary wall
thickness.
12. The surgical balloon according to claim 11, wherein the wall
thickness of the end portion is about 3 to 5 mil.
13. The surgical balloon according to claim 12, wherein the wall
thickness of the intermediate portion is about 4-6 mil.
14. The surgical balloon according to claim 13, wherein the wall
thickness of the base portion is about 5-10 mil.
15. The surgical balloon according to claim 11, wherein the second
primary wall thickness is less than the first primary wall
thickness, and the third primary wall thickness is less than the
first and second primary wall thicknesses.
16. The surgical balloon according to claim 11, wherein the end
portion is substantially hemispherical in shape.
17. A surgical balloon for insertion into a uterus, comprising: a
substantially continuous outer wall defining an exterior surface of
the balloon on a first side and an interior hollow of the balloon
on a second side, the outer wall being formed from a stretchable
elastic material and being stretchable by pressure within the inner
hollow between a collapsed state and an expanded state; the
substantially continuous outer wall having a base portion for
coupling with a catheter, and a substantially hemispherical shaped
end portion positioned at a distal end of the balloon and adjacent
the first portion, wherein, when the balloon is in the collapsed
state, the end portion has a primary wall thickness less than a
primary wall thickness of the base portion.
18. A surgical balloon for insertion into a uterus, comprising: a
substantially continuous outer wall defining an exterior surface of
the balloon on a first side and an interior hollow of the balloon
on a second side, the outer wall being formed from a stretchable
elastic material and being stretchable by pressure within the inner
hollow between a collapsed state and an expanded state; the
substantially continuous outer wall having a base portion for
coupling with a catheter, and an end portion at a distal end of the
balloon, wherein, when the balloon is in the collapsed state, the
end portion has a primary wall thickness less than a primary wall
thickness of the base portion.
19. The surgical balloon according to claim 18, wherein the end
portion is at least substantially hemispherical in shape.
20. The surgical balloon according to claim 19, wherein the end
portion is substantially symmetrical about a distal point of the
balloon.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present invention is a continuation-in-part of earlier
filed U.S. patent application Ser. No. 09/749,077, filed on Dec.
27, 2000 and entitled "Conformal Surgical Balloon With Varying Wall
Expansibility", which is incorporated by reference herein in its
entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to surgical balloons, and more
particularly to balloons suitable for introduction into a body
cavity for containing a thermally conductive media used for
ablation of cells within the cavity.
BACKGROUND OF THE INVENTION
[0003] Surgical balloons have a variety of uses, including the
containment of fluids used to necrose cells lining a body cavity.
For example, it has now become common to treat excessive menstrual
bleeding (menorrhagia) by inserting a balloon catheter into the
uterus, filling the balloon with a thermally conductive media and
heating or cooling the media to thermally kill the endometrial
lining of the uterus. An exemplary thermal ablation process and
apparatus utilizing a surgical balloon are described in U.S. Pat.
No. 5,501,681 to Neuwirth et al.
[0004] As shown in U.S. Pat. No. 5,501,681, known surgical balloons
are typically formed from latex, have a bulb shape, and inflate in
a manner which enlarges the bulb shape uniformly to an
approximately spherical or bulbous shape. In contrast, the uterine
cavity is Y-shaped in cross-section. The material composition of
known balloons is somewhat inelastic, preventing the balloons from
readily conforming to the intra-uterine space. As a result, known
bulbous surgical balloons do not inflate to contact the entire
endometrial lining, in particular, in the area of the uterine
cornua. This lack of contact may result in a portion of the
endometrial lining escaping treatment.
[0005] It is therefore an object of the present invention to
provide an improved surgical balloon that exhibits an increased
contact area with a body cavity into which it is inserted when the
balloon is inflated.
SUMMARY OF THE INVENTION
[0006] A surgical balloon is provided for insertion into a uterus.
The surgical balloon includes a substantially continuous outer wall
defining an exterior surface of the balloon on a first side and an
interior hollow of the balloon on a second side, with the outer
wall being formed from a stretchable elastic material and being
stretchable by pressure within the inner hollow between a collapsed
state and an expanded state. The substantially continuous outer
wall has a base portion for coupling with shaft, an intermediate
portion adjacent the base portion and an end portion at a distal
end of the balloon and adjacent the intermediate portion. The base
portion has a first primary wall thickness, the intermediate
portion has a second primary wall thickness, and the end portion
has a third primary wall thickness.
[0007] According to one embodiment, the wall thickness of the end
portion is about 3 to 5 mil, according to another embodiment, wall
thickness of the intermediate portion is about 4-6 mil, and in yet
another embodiment, the wall thickness of the base portion is about
5-10 mil.
[0008] According to yet another embodiment, the second primary wall
thickness is less than the first primary wall thickness, and the
third primary wall thickness is less than the first and second
primary wall thicknesses.
[0009] In an alternate embodiment, the end portion is substantially
hemispherical in shape.
[0010] Also provided is a surgical balloon for insertion into a
uterus including a substantially continuous outer wall defining an
exterior surface of the balloon on a first side and an interior
hollow of the balloon on a second side, with the outer wall being
formed from a stretchable elastic material and being stretchable by
pressure within the inner hollow between a collapsed state and an
expanded state. The substantially continuous outer wall has a base
portion for coupling with a catheter, and a substantially
hemispherical shaped end portion positioned at a distal end of the
balloon and adjacent the first portion. The end portion has a
primary wall thickness less than a primary wall thickness of the
base portion.
[0011] A surgical balloon is also provided for insertion into a
uterus having a substantially continuous outer wall defining an
exterior surface of the balloon on a first side and an interior
hollow of the balloon on a second side, with the outer wall being
formed from a stretchable elastic material and being stretchable by
pressure within the inner hollow between a collapsed state and an
expanded state. The substantially continuous outer wall has a base
portion for coupling with a catheter, and an end portion at a
distal end of the balloon. The end portion has a primary wall
thickness less than a primary wall thickness of the base
portion.
BRIEF DESCRIPTION OF THE FIGURES
[0012] For a better understanding of the present invention,
reference is made to the following detailed description of an
exemplary embodiment considered in conjunction with the
accompanying drawings, in which:
[0013] FIG. 1 is a plan view of an inflated surgical balloon in
accordance with a first exemplary embodiment of the present
invention;
[0014] FIG. 2 is a cross-sectional view of the balloon of FIG. 1 in
a deflated condition and showing the inflated condition in
phantom.
[0015] FIG. 3 is a cross-sectional view of the balloon of FIG. 2
stored within a cannula;
[0016] FIG. 4 is a plan view of an alternative embodiment of a
balloon in accordance with the present invention;
[0017] FIG. 5 is an enlarged, cross-sectional view of the tip of
the deflated balloon of FIG. 1;
[0018] FIG. 6 is an enlarged, cross-sectional view of the tip of an
alternative embodiment of the balloon of FIGS. 1 and 5 in
accordance with the present invention; and
[0019] FIG. 7 is a plan view of a surgical balloon in accordance
with an alternative exemplary embodiment of the present
invention;
[0020] FIG. 8 is a plan view of a surgical balloon in accordance
with another alternative embodiment of the present invention;
[0021] FIG. 9 is a diagrammatic view of the balloon of FIG. 8 at
three stages of inflation within a uterine cavity; and
[0022] FIG. 10 is a plan view of an alternative embodiment of a
balloon in accordance with the present invention.
DETAILED DESCRIPTION OF THE FIGURES
[0023] FIG. 1 shows a surgical balloon 10 disposed on the end of a
catheter 12. The catheter 12 has a lumen 14 that communicates with
the interior hollow 16 of the balloon 12 and permits the infusion
of a thermally conductive fluid 18 into the balloon 10 under
pressure. As is known in the art, surgical balloons may be used to
perform surgical procedures, such as endometrial ablation to cure
menorrhagia. U.S. Pat. No. 5,954,714 is incorporated herein by
reference for its teachings on the use of surgical balloons for
endometrial ablation.
[0024] The balloon 10, as described herein, can be used in place of
conventional bulb-shaped balloons to perform ablation procedures.
More particularly, after the balloon 10 is introduced into the
uterus, a pressurized thermally conductive fluid 18, e.g., saline
solution, may be used to inflate the balloon 10 within the uterus,
followed by heating or cooling of the fluid to thermally cauterize
cells in contact with the balloon 10. The balloon 10 is preferably
preformed to have a specific shape, such that when the balloon is
inflated, it conforms to the walls of the intra-uterine space. The
balloon 10 has a base 20 that is adhered to the catheter 12 by an
adhesive or by plastic welding. The body 22 of the balloon 10
extends from the base 20 and has left and right extensions 24, 26.
As can be appreciated from FIG. 1, the outer three-dimensional
shape of the balloon 10 mimics the interior hollow of a uterus when
the balloon 10 is inflated. In this manner, the balloon 10 of the
present invention can more completely fill the hollow of the uterus
into which it is inserted and contact a greater surface area
relative to a bulb shaped balloon of the prior art. More
particularly, the body 22 may extend from the isthmus to the fundus
with the left and right extensions 24, 26 inserting into the
uterine cornua. The greater contact area that may be achieved with
the balloon 10 of the present invention provides for greater
thermal transfer and more complete endometrial ablation.
[0025] FIG. 1 shows a portion of the wall 28 of the balloon 10
which has a varying thickness. More specifically, the balloon wall
28 is thick proximate the base 20 where it provides firm attachment
to the catheter 12 and where it has no need to expand. The wall 28
is thinnest in those areas requiring maximum expansion, such as the
extensions 24, 26, and of intermediate thickness in those areas
requiring intermediate expansion, e.g., body 22. That is, in
response to a given pressure, a thinner wall will expand outwardly
more than a thicker wall. By varying the wall thickness, the
balloon 10, which is bulb-shaped when deflated, can assume another
shape, e.g., mimicking the intra-uterine space, when inflated. This
shape transition of the balloon 10 occurs under the influence of
the inherent expansion characteristics of the balloon 10, rather
than in response to resistance to expansion exerted by the body
cavity. Because the balloon 10 readily assumes a complementary
shape to the body cavity in which it is placed, the balloon 10
conforms to the cavity shape without exerting as much pressure on
the body cavity as conventional balloons. In addition, an even
pressure is exerted by the balloon 10 across the internal surface
of the uterus promoting consistent and even contact therebetween
which translates to a uniform ablation depth of the cells.
[0026] As an alternative to or in addition to variations in wall
thickness giving rise to local variations in expansibility, the
wall 28 may be treated with heat, radiation or chemicals to achieve
the same effect. More particularly, the balloon 10 can be made from
polyurethane with a selected area exposed to heat in a temperature
range of 260.degree. F. to 280.degree. F. by inserting the balloon
10 into an apertured mask made from aluminum or steel and exposing
the balloon 10 to a heat source which will effect only the unmasked
area. Alternatively, the balloon 10 may be installed upon a
stretching frame and selected surfaces subsequently branded with
heated dies. Alternatively, the balloon 10 may be stretched upon a
frame and subjected to chemicals such as, dimethyl sulfoxide or
tetrahydrofuran, that are printed on, brushed, dabbed or sprayed on
through a mask.
[0027] The balloon 10 may be blow molded from polyester or
polyethylene resins; dip molded from silicones, natural latex
rubber or polyisoprene, a synthetic rubber; extrusion molded from
silicone; injection molded from polyurethanes or silicones; or
formed by heat sealing sections (patterns) together. Currently, the
preferred method of manufacture is dip molding using natural latex
rubber or polyisprene. Other compounds from which the balloon 10
can be made using one or more of the foregoing processes are
polyether block amides, polyolefins and co-polyesters.
[0028] As referred to above, the balloon 10 can be formed by heat
sealing, viz., by cutting patterns of a sealable expandable
material into specific shapes and then heat sealing the edges of
the two identical shapes together. This can produce a structure,
which has a volume between the top and bottom patterns. An
alternate method is to place two sheets of material together, one
on top of the other. A formed die is then placed on either side of
the two sheets, and the die is heated to melt the sections of the
sheets between the corresponding sections of the die. This area
creates a seal when it cools. The shape or configuration of the die
determines the shape of the balloon 10.
[0029] The balloon 10 of the present invention can be used in hot
ablation procedures and in cryoablation. Materials, which are best
suited for hot ablation procedures, would include polyisoprene,
silicone and natural latex rubber. The material best suited for use
in cold ablation procedures would be silicone.
[0030] Polyurethane, in contrast to the latex compounds that have
previously been used to make surgical balloons, is highly elastic
and permits the balloon 10 to conform readily to the intrauterine
space, even with minimal or no variations in flexibility of the
wall 28. Accordingly, the present invention is intended to include
the use of polyurethane to produce a surgical balloon with either
constant or varying wall thickness to insure low pressure
conformation to the intrauterine shape.
[0031] FIG. 2 illustrates the balloon 10 of FIG. 1 in a deflated
state and the left and right extensions 24, 26 appearing as
internal surface indentations due to wall thinning in that area.
The thickness of the wall 28 ramps down from the base 20 (which is
thickest) to the body 22 (which is of intermediate thickness) and
then to the extensions 24, 26 (which have the thinnest walls). It
should be appreciated that the variation in the thickness of the
wall 28 depicted in FIGS. 1, 2 and 3 is exaggerated for the
purposes of illustration. In general, it is preferable for the
thinning of the wall 28 to occur inside the balloon 10, in a
symmetrical fashion. This will produce an even expansion of the
outer surface. The transition from thin wall section to thick wall
section will be smooth on the external surface of the balloon 10 in
this configuration. Sharp changes in wall thickness will produce
areas of high stress concentration, which will weaken the balloon
10 at those sites. This could lead to balloon failure during
expansion.
[0032] As can be appreciated from FIG. 3, the deflated balloon 10
is readily accommodated within the lumen 29 of a cannula or
introducer tube 30 that is used to facilitate introduction and
deployment of the catheter 12 and balloon 10 into the uterus of a
patient. More particularly, the cannula 30 can be slipped through
the uterine os, followed by urging of the catheter 12 forward to
deploy the balloon 10 beyond open tip 32 of the cannula 30. In the
alternative, the cannula 30 can be withdrawn backward off of the
balloon 10, exposing it in place. Once the balloon 10 is
unconstrained by the cannula 30, it can be expanded under the
influence of the infusion of thermally conductive fluid into the
balloon 10, inflating it to the shape shown in FIG. 1.
[0033] A commonly owned copending application Ser. No. 09/749,180,
entitled CONFORMAL SURGICAL BALLOON and filed contemporaneously
herewith by the present inventors, discloses a surgical balloon
that conforms to the intra-uterine space aided by its preformed
shape, such copending application being incorporated herein by
reference. The present invention therefore contemplates a preformed
surgical balloon (mimicking the uterine cavity shape) wherein the
wall thickness and/or wall elasticity varies in accordance with the
teachings of the present application, to aid in permitting the
balloon to conform to the body cavity in which it is inflated. In
particular, it is beneficial for the extensions 24, 26 of such a
preformed balloon to have a thinner wall thickness and/or greater
expansibility than the remainder of the balloon. Besides aiding the
expansion of the extensions 24, 26 into the uterine cornua, the
thinned extensions 24, 26 of a deflated preformed balloon can be
more readily and compactly folded for storage within the cannula 30
and can be deployed more readily.
[0034] In the description to follow, a numbering convention will be
used wherein elements having a similar function to a preceding
embodiment shall have the same reference numerals increased by one
hundred.
[0035] FIG. 4 shows how a preformed balloon 110 with thinned
extensions 124, 126 is folded to allow storage in the cannula 30
(see FIG. 3) and to facilitate a controlled unfolding and
deployment when the balloon 110 is pushed out of the cannula 30
into the uterus. More specifically, the extensions 124, 126 are
folded in a zig-zag configuration. Preferably, the balloon 110 is
stored in a folded configuration that provides for a sequenced
unfolding that properly positions the balloon 110 within the uterus
to facilitate optimal balloon-to-endometrial lining contact when
the thermally conductive media is infused into the balloon 110,
inflating it and filling the intra-uterine space. When applied in
the treatment of a body cavity having a directional sense, such as
the uterus, the balloon 110 has a shape that requires orientation
relative to the specific orientation of the body cavity in which it
is deployed. The cannula 30 (see FIG. 3) and/or the catheter 112
are therefore preferably provided with an orientation marking that
allows the surgeon to insert the balloon 10 in the proper
orientation relative to the patient. To maintain the relative
position of the catheter 112 and the cannula 30, it is preferred
that each be keyed relative to the other, e.g., that the catheter
112 be provided with a longitudinal ridge that fits within a mating
guide way in the cannula 30. In this manner, the orientation of the
balloon 1 10 is preserved, while the balloon 110 is rotationally
fixed relative to the cannula 30 and, in the case of a folded
preformed balloon, avoiding inadvertently disturbing the folded
position of the balloon 110.
[0036] The selection of material for the balloon 10, 110 insures
that the balloon 10, 110 will not stick to itself or the cannula 30
after prolonged storage within the cannula 30. Alternatively, the
balloon 10, 110 may be coated with a conventional biocompatible,
non-allergenic lubricant, such as talc, cornstarch or low viscosity
silicone, preferably air cured to prevent self-adhesion. In order
to promote deployment of a folded balloon 110, it is preferably
folded in a manner that minimizes overlap, severity of fold angle
and compression forces that exceed the elastic limit of the
material at fold lines. In addition, it is preferable that the
extensions 124, 126 be folded at intervals that are smaller in
length than the spacing between any opposed surfaces within the
uterine cavity that could trap the extensions 124, 126 in an
unfolded condition, e.g., between the walls of the uterine cornua
or between the body of the balloon 110 and the uterine wall.
[0037] FIG. 5 shows a distal fragment of the balloon 10 of FIG. 3
illustrating how the wall 28 thickness may be selectively varied in
accordance with the present invention. More specifically, the
thickness of the wall 28 at the tip 32 and body 22 portions is
thinned in the area of the extensions 24, 26 by varying the
internal diameter of the balloon 10 from Db to D.sub.e with the
outer diameter D.sub.o remaining constant.
[0038] FIG. 6 illustrates an alternative approach to that shown in
FIG. 5, wherein the outer diameter D.sub.o of a balloon 210,
decreases from that present on body 222 portion to a lesser
diameter associated with extensions 224, 226, with the internal
diameter D.sub.i remaining constant.
[0039] FIG. 7 shows a balloon 310 in accordance with the present
invention and having an outwardly flaring body 322, the upper
peripheral edge 323 of which is intended to extend into the uterine
cornua of a patient. The body 322 is axially symmetric, i.e.,
generally bell-shaped. The shape of the balloon 310 can be
determined by varying wall expansibility and/or pre-forming, such
that the balloon 310 shown in FIG. 7 could be in the partially
inflated state, i.e., having assumed that shape due to selected
localized expansion characteristics of the wall of the balloon 310.
Alternatively, the balloon 310 may be pre-formed, such that the
shape shown is present when the balloon is inflated. In the case of
a pre-formed balloon 310 having an uninflated shape as shown,
variations in wall expansibility may be incorporated therein in
order to further assist the balloon 310 in conforming to the body
cavity when it is more fully inflated. When inflated, the overall
shape of the balloon 310 and corresponding distribution of flexible
wall material allows the upper peripheral edge 323 to expand out
into the cornua. The body 322 flares out rapidly from the base 320
to a lower circumference 321 to increase contact with the uterus
proximate the uterine os. This effect is illustrated in FIG. 9
described below:
[0040] FIG. 8 shows a balloon 410 having a shape similar to the
balloon 310 of FIG. 6, but with an expandable upper flange 424 to
facilitate expansion into the uterine cornua. FIG. 9 illustrates
the balloon 410 within a uterine cavity U, in the uninflated state,
in an intermediate state of inflation 410' (dotted) and inflated
almost completely 410'=(dotted). As the balloon 410 is inflated,
the expansible flange 424, (424', 424'=) approaches and enters the
uterine cornua C.sub.1, C.sub.2. Simultaneously, lower
circumference 421, (421', 421'=) immediately expands outwardly to
contact the uterine cavity U proximate the os O. Depending upon the
shape of the uterine cavity U, the lower circumference 421'=may
project downwardly to fill the space between the base 420 and the
uterine cavity U proximate the os O. Alternatively, the expansion
of the balloon 410 will push the base 420 in an outward direction
(to a lesser degree of insertion) such that the balloon 410 will
establish maximum contact with the uterine cavity U. Accordingly,
surgical balloons 10, 110, 210, 310, 410 establish greater contact
with the uterine cavity U more quickly and completely than a
conventional bulb-shaped balloon. Since the balloons 10, 110, 210,
310, 410 more readily inflate to a shape approximating the cavity
into which they are inserted, greater contact area at a more even,
higher pressure is achieved, assuring better thermal transfer.
[0041] It should be appreciated that the present invention
contemplates a balloon 10,110, 210, 310, 410 with a symmetrical
radial thinning or treatment such that the thinned area, if
inflated outside the body, would assume a toroidal, radially
symmetric shape. If the same balloon were inflated within the body,
e.g., the uterus, then the thinned area would be constrained by the
cavity shape such that the extensions 24, 26 (224, 226) can extend
into the uterine cornua. Under such circumstances, the balloon will
be radially symmetric such that there is no need to provide a means
to radially align the balloon to the uterus.
[0042] Alternatively, the thinning or treatment of the balloon
10,110, 210 may be localized such that the extensions 24, 26 (124,
126 and 224, 226) project out like fingers. In that case, the
alignment means referred to above in reference to FIG. 4 is
preferred in order to align the balloon 10, 110, 210 to the body
cavity.
[0043] Referring now to FIG. 10, yet another embodiment of a novel
surgical balloon 500 is provided the outer walls of which vary in
thickness at specified locations. The balloon has a substantially
continuous outer wall 502 defining an exterior surface 504 of the
balloon on a first side, and defining an inner hollow 506 of the
balloon on a second side. The balloon 500 further includes a base
portion 508, and a body portion 510 including an intermediate
portion 512 and an end portion 514. In the illustrated embodiment,
the end portion 514 substantially forms a hemispherical shape
relative to center point P. The end portion may also simply be
substantially symmetrical about a distal tip T of the balloon,
which could constitute more or less than a hemisphere. As will be
described in further detail below, the continuous outer wall of the
balloon 500 decreases in thickness from the base portion to the end
portion, with each successive portion having a primary wall
thickness less than that of the one before. For the purposes of
this disclosure, "primary wall thickness" of a designated portion
refers to the wall thickness of that portion, excluding any
standard tolerance variations and any transition area to an
adjacent portion having a different primary wall thickness In a
preferred embodiment, the balloon is a dipped silicon balloon that
may be manufactured by well known single or multiple dip processes
in which the dipping parameters and orientations are controlled to
yield the desired thickness. Injection molding or other molding
techniques may also be used. The primary wall thickness of the base
portion is from 5-10 mil, the primary wall thickness of the
intermediate portion is from 4-6 mil, and the primary wall
thickness of the end portion is from 3-5 mil. Although the ranges
above appear to overlap, it is to be understood that primary wall
thickness of end portion will be less than the primary wall
thickness of the intermediate portion, which in turn will be less
than the primary wall thickness of the base portion; for example 8
mil, 5 mil and 4 mil respectively. It is also to be understood that
the thickness of a distal tip portion T of the balloon may have a
wall thickness greater than that of the end portion as a result of
the inherent effects of well known balloon dipping processes. Such
a tip portion will not adversely affect balloon performance as
described below, and is excluded when considering the "primary wall
thickness" of the end portion.
[0044] It has been found that a balloon of the type described above
is advantageous in that the end portion, particularly when
hemispherical in shape, will expand more than the intermediate
portion to conform better to the inner contour of the upper portion
of the uterus, to thereby better fill both uterine cornua. In this
manner, contact area is increased making the treatment more
effective.
* * * * *