U.S. patent application number 11/017710 was filed with the patent office on 2005-05-26 for heat transfer catheters and methods of making and using same.
This patent application is currently assigned to Radiant Medical, Inc.. Invention is credited to Saab, Mark A..
Application Number | 20050113893 11/017710 |
Document ID | / |
Family ID | 46278560 |
Filed Date | 2005-05-26 |
United States Patent
Application |
20050113893 |
Kind Code |
A1 |
Saab, Mark A. |
May 26, 2005 |
Heat transfer catheters and methods of making and using same
Abstract
Heat transfer catheter apparatus and methods of making and using
same are disclosed wherein a fluid connection is provided between
the distal portions of two adjacent, thin-walled, high strength
fluid lumens to define a closed loop fluid circulation system
capable of controlled delivery of thermal energy to or withdrawal
of thermal energy from remote internal body locations.
Inventors: |
Saab, Mark A.; (Lowell,
MA) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Radiant Medical, Inc.
Redwood City
CA
|
Family ID: |
46278560 |
Appl. No.: |
11/017710 |
Filed: |
December 22, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11017710 |
Dec 22, 2004 |
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10184889 |
Jul 1, 2002 |
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10184889 |
Jul 1, 2002 |
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09309052 |
May 10, 1999 |
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6440158 |
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09309052 |
May 10, 1999 |
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08453066 |
May 26, 1995 |
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5902268 |
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08453066 |
May 26, 1995 |
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08287114 |
Aug 8, 1994 |
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5624392 |
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08287114 |
Aug 8, 1994 |
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07929305 |
Aug 13, 1992 |
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5342301 |
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Current U.S.
Class: |
607/105 ;
604/113 |
Current CPC
Class: |
A61F 2007/0054 20130101;
A61M 2025/0025 20130101; A61F 7/123 20130101; A61M 2025/1072
20130101; A61M 25/0029 20130101; A61M 2025/1031 20130101; A61M
25/1027 20130101; A61M 25/104 20130101; A61B 2018/00166 20130101;
A61M 25/0032 20130101; A61M 25/1029 20130101; A61F 2007/126
20130101; A61M 2025/0031 20130101; A61M 2025/1075 20130101; A61M
2025/1086 20130101; A61M 25/0009 20130101; A61M 2025/0034 20130101;
A61M 2025/0036 20130101; A61M 29/02 20130101 |
Class at
Publication: |
607/105 ;
604/113 |
International
Class: |
A61F 007/00 |
Claims
1-73. (canceled)
74. A heat transfer catheter apparatus, comprising: (a) a
substantially elongate shaft; (b) at least one first lumen internal
to said substantially elongate shaft, said at least one internal
lumen configured: (i) to circulate a working fluid; (ii) to inflate
under pressure of said working fluid; and (iii) to collapse under
vacuum; and (c) a second lumen external and adjacent to said
substantially elongate shaft, said second lumen having a spiral
shape; wherein said second lumen is configured to extract said
circulating working fluid.
75. The catheter apparatus according to claim 74, wherein said
first and second lumens are formed of a flexible material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation-in-part of both U.S.
patent application Ser. No. 08/059,725, filed May 10, 1993, and now
pending, which in turn was a continuation of U.S. patent
application Ser. No. 07/522,178, filed May 11, 1990, now abandoned,
and also of U.S. patent application Ser. No. 07/929,305, filed Aug.
13, 1992, and now pending. The disclosures of these related prior
pending applications are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to heat transfer
catheter apparatus for internal body applications, and more
particularly, to catheters adapted for delivering heat transfer
fluids at temperatures above or below normal body temperatures to
selected internal body sites that are relatively remote from the
point of entry into the body for specialized medical applications.
The heat transfer catheters of this invention may, in one
embodiment, comprise fluid lumens that have very thin-walled, high
strength sidewalls that are substantially inelastic. In an
alternative embodiment, the fluid lumen sidewalls may be
elastomeric. In either case, the fluid lumens are readily
inflatable under fluid pressure and readily collapsible under
vacuum. The heat transfer catheter apparatus of this invention may
comprise multi-lumen units having two or more lumens. The heat
transfer catheter apparatus of this invention may also, in
different embodiments, be used alone or in conjunction with other
medical apparatus. The heat transfer catheter apparatus of this
invention may also, in different embodiments, comprise single or
multi-lumen dilatation balloons.
[0003] It is well known in the art to prepare and use catheters for
a variety of medical applications. In one familiar application,
inexpensive, disposable catheters having one open end and one
closed end are utilized as protective sheaths for various medical
instruments. The use of such elongated, tubular sleeves as
protective sheaths can minimize the costs and problems associated
with cleaning and sterilizing medical instruments, such as
endoscopes, between uses. In the case of medical optical
instruments, such as endoscopes, the protective sleeves may include
a "window" portion designed to align during use with the optical
portion of the medical instrument.
[0004] Typical of the prior art in this field are U.S. Pat. Nos.
4,646,722 (Silverstein et al.) and U.S. Pat. No. 4,907,395 (Opie et
al.). The Silverstein et al. patent teaches the use of an endoscope
sheath comprising a flexible tube surrounding the elongated core of
an endoscope. The flexible tube has a transparent window near its
distal end positioned in front of the viewing window of the
endoscope. An alternative embodiment of the Silverstein et al.
sheath for use with side-viewing endoscopes is shown in FIG. 10 of
that patent. In this embodiment, the sheath 110 comprises an end
cap 112 of relatively rigid material mounted at the end of a
flexible cylindrical tube of elastomeric material 114 formed into a
roll 116. The end cap 112 includes a pair of transparent windows
118, 120. The later Opie et al. patent is essentially an
improvement invention directed to a method of packaging and
installing the endoscope sheaths of the Silverstein et al.
patent.
[0005] U.S. Pat. Nos. 3,794,091 (Ersek et al.) and U.S. Pat. No.
3,809,072 (Ersek et al.) are directed to sterile sheaths for
enclosing surgical illuminating lamp structures that have elongated
light transmitting shafts. The sheaths in Ersek et al. are
fabricated from films of flexible plastic material, such as vinyl
tubing, polyethylene or polypropylene. Ersek et al. prefer a wall
thickness of between three and six mils for the required
durability, rigidity and transparency. The tip end portion 20 of
the sheath is described as a "generally rigid lens element" sealed
to the sheath in a continuous sealing line 21 by thermal welding or
adhesive bonding.
[0006] U.S. Pat. No. 4,957,112 (Yokoi et al.) describes an
ultrasonic diagnostic apparatus, the distal end portion of which
includes a cover 24 made of a thin, hard, polyethylene sheet that
has a window portion 34 along a sidewall. U.S. Pat. No. 4,878,485
(Adair) describes a rigid, heat sterilizable sheath S that provides
an outer casing for a video endoscope. The sheath includes a
viewing window 32, a flat disc positioned at the distal end in the
optical path of the endoscope. U.S. Pat. No. 4,819,620 (Okutsu)
describes an endoscope guide pipe which is rigid and formed from a
transparent material such as glass or plastic. In one embodiment
shown in FIG. 6 of that patent, a pair of slots in the sidewall of
the guide pipe is filled with a transparent material, such as
glass, to define a window section 12f. U.S. Pat. No. 4,470,407
(Hussein) describes a flexible, elongated tube with an elastomeric
balloon sealingly mounted at the distal end of the tube for
enclosing an endoscope. Inside the body, the balloon can be
inflated to facilitate endoscope viewing. U.S. Pat. No. 4,201,199
(Smith) describes a relatively thick, rigid glass or plastic tube
10 which fits over an endoscope. The distal end of the tube in the
Smith patent is provided with an enlarged, sealed bulb 12 having a
radius of at least 34 mm to reduce optical distortion caused by a
too-small radius of curvature. U.S. Pat. No. 3,162,190 (Del Gizzo)
describes a tube 19, made from molded latex or similar material,
through which an optical instrument is inserted. Viewing is through
an inflatable balloon element 24 mounted at the distal end of the
tube. U.S. Pat. No. 3,698,791 (Walchle et al.) describes a very
thin, transparent microscope drape which includes a separately
formed, optically transparent, distortion-free lens for
viewing.
[0007] In another familiar application, multi-lumen balloon
catheters are utilized as dilatation devices for dilating a blood
vessel, e.g. a coronary artery, or other body canal. The use and
construction of balloon catheters is well known in the medical art,
as described for example in U.S. Pat. No. Re. 32,983 (Levy) and
U.S. Pat. No. 4,820,349 (Saab). Other patents generally showing the
application of various types of balloon catheters include U.S. Pat.
No. 4,540,404 (Wolvek), U.S. Pat. No. 4,422,447 (Schiff), and U.S.
Pat. No. 4,681,092 (Cho et al.).
[0008] It is also well known in the medical art to employ catheters
having shafts formed with a plurality of lumens in instances where
it is necessary or desirable to access the distal end of the
catheter or a particular internal body location simultaneously
through two or more physically separate passageways. For example,
U.S. Pat. No. 4,576,772 (Carpenter) is directed to increasing the
flexibility or articulatability of a catheter having a shaft formed
with a plurality of lumens that provide distinct conduits for
articulating wires, glass fiber bundles, irrigation, and vacuum
means.
[0009] It is also known, as shown in U.S. Pat. No. 4,299,226
(Banka) and U.S. Pat. No. 4,869,263 (Segal et al.), to employ
multi-lumen catheters with a balloon. The Banka patent shows a
double-lumen catheter shaft of coaxial construction wherein the
outer lumen carries saline solution to inflate a balloon, and an
inner lumen, located coaxially inside the outer lumen, is adapted
to receive a stylet or guide wire. In the Banka patent, the
double-lumen dilatation catheter is designed to be coaxially
contained within the single lumen of a larger diameter guide
catheter. In the Banka device, each of the three coaxial lumens is
a separate, distinct passageway without any means for fluid passage
between two of those lumens. Such fluid passage between lumens
could occur only accidentally in the event of a rupture of one of
the lumens, and such results are clearly contrary to the intent of
that patent.
[0010] The Segal et al. patent shows a more complex dilatation
catheter apparatus having five separate, non-coaxial lumens (FIGS.
1 and 2 of that patent) extending through the catheter, including a
balloon inflation lumen 18, a distal lumen 17, a wire lumen 22, a
pulmonary artery lumen 26, and a right ventricular lumen 28. Lumens
17 and 18 extend the entire length of the catheter from the
proximal extremity to the distal extremity. Lumen 17 exists through
the distal extremity 14b of the catheter. The distal extremity of
lumen 18 is in communication with the interior of balloon 16 to
permit inflation and deflation. Lumens 22, 26 and 28, on the other
hand, only pass partly or completely through the larger diameter,
proximal portion 14a of the catheter. The Segal et al. catheter
apparatus is prepared by extrusion (col. 2, lines 53 and 54).
Multi-lumen catheters in conjunction with a balloon or inflatable
element have also been adapted for a variety of special usages.
U.S. Pat. No. 4,994,033 (Shockey et al.) and U.S. Pat. No.
5,049,132 (Shaffer et al.) are both directed to balloon catheters
adapted for intravascular drug delivery. Both of these patents
employ a similar concentric, coaxial, double balloon construction
surrounding a central lumen. The larger, outer balloons in both
cases include a set of apertures for the delivery of medication to
surrounding tissue when the catheter is in place. No fluid
connection or passageway is provided between the inner and the
outer balloons or the lumens serving those balloons in these
patents.
[0011] U.S. Pat. No. 4,681,564 (Landreneau) teaches another type of
multi-lumen catheter in conjunction with a balloon element. In this
patent, a first fluid passage is in communication with the balloon
element so as to selectively inflate or deflate it; a second,
separate fluid passage has outlet openings at its distal end for
purposes of delivering medication or other treating fluid to the
body space; and, a third, separate passage has drain openings
communicating with the body space so as to drain excess fluids.
This patent thus describes a catheter loop whereby treating fluid
enters the body through a first lumen and some portion of that
fluid leaves the body through a separate second lumen. But, this is
clearly not a closed loop in the sense that some portion of the
treating fluid remains in the body, and all of the treating fluid
must pass through a portion of the human body on its way from the
inlet lumen to the drainage passage. Such treating fluid certainly
could not contain toxic substances which would poison or harm the
body.
[0012] U.S. Pat. Nos. 4,581,017 (Sahota) and U.S. Pat. No.
5,108,370 (Walinsky) are both directed to perfusion balloon
catheters designed to maintain blood flow through a blood vessel
during a dilatation procedure, for example an angioplasty. In
Sahota, a hollow, central shaft passes through the interior of the
balloon element, and apertures in the side wall of the catheter
shaft upstream and downstream from the balloon permit blood to flow
into the shaft, past the balloon, and back into the blood vessel. A
small, separate tube connected to the balloon is used to inflate
and deflate the balloon. No fluid connection is provided between
the balloon and the central shaft. A generally similar balloon
catheter construction is described in Walinsky.
[0013] U.S. Pat. No. 4,299,237 (Foti) is directed to an apparatus
for transferring thermal energy from a calorized fluid to an ear
canal and tympanic membrane. In one embodiment, this apparatus
comprises a rigid structure made of a semi-rigid material and
pre-shaped so as to conform to the internal geometry of an ear
canal. Rigid internal struts keep open a fluid circulation loop
served by a fluid inlet tube and a fluid outlet tube. In an
alternative embodiment, the Foti apparatus comprises an inflatable
balloon element surrounding a hollow, central shaft containing a
depth indicator for proper positioning of the device. The balloon
element is inflated and deflated through separate fluid inlet and
outlet tubes connected through a rigid ear mold adjoining the
balloon element. The Foti apparatus in either embodiment is
relatively short (typically about 32 mm in length) and relatively
wide (overall diameter of about 6 mm), therefore bearing little
resemblance to a vascular-type catheter which is typically several
hundred millimeters in length but with a diameter of only about
three--four millimeters or less. Furthermore, the Foti device is
designed to operate only at a relatively low fluid pressure because
it is not intended for dilating internal body canals and also
because there is no need to force fluid through a very small
diameter conduit over relatively long distances, again in contrast
to a vascular-type dilatation catheter.
[0014] In the above-cited prior art, which is incorporated herein
by reference, it should be understood that the term "multi-lumen"
in the phrase "multi-lumen balloon catheters" typically means that
the catheter shaft is multi-lumen (as opposed to the balloon
segment in communication with the catheter shaft). By contrast, my
U.S. patent application Ser. No. 07/929,305, of which this
application is a continuation-in-part, is directed to novel
multi-lumen balloons. The multi-lumen balloons of my aforementioned
invention are distinguished from the multi-lumen balloon catheters
of the prior art, as discussed above, in that the walls defining
the lumens are formed as an integral part of the balloon. The terms
"integral part" and "integrally formed" as used in Ser. No.
07/929,305 each mean that at least a lumen of the multi-lumen
balloon shares a common wall portion with part of at least one
inflatable balloon segment. By contrast, the prior art shows lumens
that are formed as a part of a conventional catheter shaft and are
defined by the relatively thick walls of that catheter (e.g. Segal
et al.), catheter lumens that communicate with or terminate in a
balloon segment (e.g. Banka and Segal et al.), and lumens in a
shaft that passes coaxially through a balloon segment (e.g. Banka,
Sahota, and Walinsky).
[0015] In many conventional and non-conventional medical catheter
applications, it would be desirable to provide a means for
continuously transferring over an extended time period controlled
amounts of thermal energy to or away from one or more adjacent
locations along or at the distal end of an elongated, vascular-type
catheter. Heat transfer can be effected, of course, by circulating
a heat transfer fluid inside a catheter lumen. This straightforward
approach is complicated, however, by enormous and heretofore
unsurmountable physical limitations and obstacles.
[0016] Thus, a single lumen catheter can certainly deliver a heat
transfer fluid to the closed distal end of the catheter. But, if
the heat transfer fluid is at a temperature different from body
temperature, the result of this procedure would be to merely create
a temporary temperature gradient along the length of the catheter.
At locations distal from the point where the fluid was introduced
to the catheter, the temperature of the fluid in the catheter would
tend to approach the internal body temperature. Furthermore, even
this temperature effect would exist for only a relatively short
time until the fluid at every point along the catheter gradually
heated or cooled to body temperature. Clearly, this approach cannot
be used to continually transfer controlled amounts of thermal
energy to or away from internal body locations over an extended
time period.
[0017] To effect continuous, controlled transfer of thermal energy
to or from a body location adjacent the catheter therefore
requires, at a minimum, a two-lumen catheter construction. With
such a two-lumen construction, a continuous flow of heat transfer
fluid can, at least in theory, be established. Fresh fluid at any
desired temperature can be continuously introduced at the proximal
end of a first or inlet catheter lumen and passed through that
first lumen to a distal location inside the body, then passed
through fluid connection means directly to the second or outlet
catheter lumen, and finally passed back along that second lumen to
be withdrawn at the proximal end as spent fluid for discarding or
recycling. If the continuous fluid flow rate through such a
two-lumen catheter system is sufficiently rapid, this construction
makes it possible to establish and substantially maintain a fluid
temperature inside the catheter that is above or below normal body
temperature at any location along the length of the catheter.
Correspondingly, if the catheter is constructed of a material which
has good heat transfer properties and which is also sufficiently
flexible so as to closely conform to the surrounding body cavity,
the temperature of the fluid inside the catheter can be transferred
to adjacent portions of the body that are in contact with or in
proximity to the catheter sidewalls.
[0018] There are problems, however, associated with a two-lumen
catheter configuration for carrying heat transfer fluid. A
principal problem with such a configuration, utilizing conventional
catheter and balloon construction and materials, relates to the
size of the final apparatus. It will be apparent to those skilled
in the art that catheter constructions intended for blood vessels
and similar very small diameter body passages must be of
correspondingly small diameter. This size problem is exacerbated by
a two-lumen catheter construction, whether the lumens are
configured side-by-side or concentrically. In either case, a
significant proportion of the limited space inside the blood vessel
or other body passage is occupied by relatively thick catheter
sidewalls leaving relatively little open cross-sectional area for
circulating fluids or as passageways for medical instruments and
the like.
[0019] For example, the relatively thick sidewalls that define the
lumens of conventional multi-lumen catheters, such as in the prior
art patents cited above, typically range from about 0.003 to about
0.010 inches or greater. In part, the reason that conventional
multi-lumen catheters have utilized such thick sidewalls is because
these devices are fabricated from materials that are not high in
tensile strength. Most balloon catheter shafts have conventionally
been made by extrusion of a thermoplastic material. The resulting
shafts are typically not substantially oriented, therefore not high
tensile strength. Because rupture of one of these catheters while
in use might cause air bubbles or dangerous fluids to leak into the
blood stream resulting in death or serious injury, the catheter
sidewalls had to be made thick enough to insure safety and
reliability. This was especially important where the catheter was
intended to carry fluid under pressure. Furthermore, such
thick-walled catheter lumens are not readily inflatable under fluid
pressure nor readily collapsible under vacuum, thereby complicating
the process of inserting or withdrawing these devices.
[0020] With a conventional balloon dilatation catheter used, for
example, for an angioplasty procedure, a relatively narrow
cross-sectional catheter opening due to the relatively thick
catheter sidewalls might be a nuisance but generally would not
completely defeat the purpose of such a catheter. Such a device
would still generally function as long as sufficient fluid could
gradually be transferred through the catheter shaft in order to
inflate the balloon and thereby dilate the blood vessel. By
contrast, for a heat transfer catheter, the inability to establish
and maintain a relatively high fluid flow rate through the catheter
would completely defeat the purpose of continuously transferring
controlled amounts of thermal energy to or away from remote
internal body locations. A slow or uneven flow of heat transfer
fluid through the catheter lumen would be unable to overcome the
continuous heating or cooling effect of the surrounding body tissue
along the relatively long length of the catheter. Moreover, if the
heat transfer catheter was intended to be used in conjunction with
a dilatation balloon, or with a guide wire, or with a medical
instrument, a third, a fourth or additional catheter lumens would
need to be provided, each defined by its own relatively thick
sidewalls, thereby further restricting the already limited open,
cross-sectional area.
[0021] Still another problem with the conventional thick-walled
multi-lumen catheter is that the relatively thick sidewalls act as
insulation and reduce heat transfer between any fluids inside and
the surrounding body tissue. Yet another problem with the
conventional thick-walled multi-lumen catheters is that the thick
walls tend to be relatively rigid and thus do not closely conform
to the surrounding body canal, thereby further reducing heat
transfer.
[0022] These and other problems with and limitations of the prior
art catheters in connection with heat transfer applications are
overcome with the heat transfer catheters of this invention.
OBJECTS OF THE INVENTION
[0023] Accordingly, it is a general object of this invention to
provide a catheter apparatus suitable for heat transfer
applications inside a living body together with methods for making
and using such apparatus.
[0024] A principal object of this invention is to provide a heat
transfer catheter with fluid lumens having at least in part very
thin, high strength sidewalls that are readily inflatable under
fluid pressure and readily collapsible under vacuum.
[0025] It is also an object of this invention to provide a heat
transfer catheter having fluid lumens with very thin, high strength
sidewalls that have high heat transfer properties.
[0026] A further object of this invention is to provide a heat
transfer catheter having fluid lumens with very thin, high strength
sidewalls that, when inflated under fluid pressure, closely conform
to the geometry of the surrounding body cavity.
[0027] A specific object of this invention is to provide a catheter
apparatus capable of continuously transferring controlled amounts
of thermal energy to or away from adjacent internal body locations
that are relatively distant from the point of entry of the catheter
into the body over an extended period of time.
[0028] Still another specific object of this invention is to
provide a heat transfer balloon dilatation catheter capable of
dilating a remote internal body location while simultaneously
delivering controlled amounts of thermal energy to or withdrawing
controlled amounts of thermal energy from an adjacent body
location.
[0029] Yet another specific object of this invention is to provide
a heat transfer catheter for enclosing a diagnostic or therapeutic
instrument while simultaneously transferring controlled amounts of
thermal energy to or away from all or a portion of the
instrument.
[0030] These and other objects and advantages of this invention
will be better understood from the following description, which is
to be read together with the accompanying drawings.
SUMMARY OF THE INVENTION
[0031] The heat transfer catheter apparatus of the present
invention comprises very thin-walled, high strength thermoplastic
tubular material defining a plurality of lumens, at least two of
which are adjacent and readily inflatable under fluid pressure and
readily collapsible under vacuum. Fluid connection means are
provided at or proximate to the distal ends of the two adjacent
lumens to define a closed loop fluid containment and circulation
system whereby heat transfer fluid from a first, inlet lumen is
passed directly to a second, outlet lumen such that a continuous
flow of heat transfer fluid through the two lumens can be
established and maintained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a schematic longitudinal sectional view of a heat
transfer catheter apparatus according to one embodiment of the
invention.
[0033] FIG. 2 is a cross-sectional view of the catheter apparatus
of FIG. 1 along the line 2-2.
[0034] FIG. 3 is a schematic longitudinal sectional view of a heat
transfer balloon dilatation catheter apparatus according to another
embodiment of the invention.
[0035] FIG. 4 is an isometric view of a heat transfer balloon
dilatation catheter apparatus similar to FIG. 3 but also comprising
three straight, perimetrical lumens adjacent to the balloon
wall.
[0036] FIG. 5 is a cross-sectional view of the catheter apparatus
of FIG. 4 along the line 5-5.
[0037] FIG. 6 is an isometric view of a heat transfer balloon
dilatation catheter apparatus similar to FIG. 3 but also comprising
a helical, perimetrical lumen having pin holes for delivering fluid
to a body cavity.
[0038] FIG. 7 is a cross-sectional view of the balloon portion of
another type of multi-lumen heat transfer balloon dilatation
catheter apparatus according to another embodiment of this
invention.
[0039] FIG. 8 is a cross-sectional view of the balloon portion of
still another type of multi-lumen heat transfer balloon dilatation
catheter apparatus according to the present invention.
[0040] FIG. 9 is a schematic, isometric, partial cross-sectional
view of a heat transfer catheter according to still another
embodiment of the invention.
[0041] FIG. 10 is a schematic cross-sectional view of a heat
transfer catheter according to yet another embodiment of the
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0042] In each of the drawings, as described below, it should be
understood that the wall thicknesses of the catheter and balloon
lumens have been greatly exaggerated relative to other elements and
to other dimensions for purposes of illustration.
[0043] FIG. 1 shows a schematic longitudinal sectional view of a
heat transfer catheter apparatus 10 according to the present
invention comprising a substantially concentric, coaxial
configuration of multiple lumens or channels. The concentric,
coaxial arrangement of the multiple lumens can be better understood
by reference to FIG. 2, a cross-sectional view taken along the line
2-2 of FIG. 1. Returning to FIG. 1, a first, inner catheter tube 12
defines a central conduit 11 receiving a guide wire 13. Catheter
tube 12 may be of conventional, thick-walled construction or,
alternatively, comprise very thin sidewalls. For purposes of this
invention, the terms "very thin walls" or "very thin-walled" refer
to elongated sleeves or catheters having sidewalls ranging in
thickness from about 0.0002 inches up to about 0.002 inches, and,
in some preferred embodiments, a wall thickness not exceeding
0.0009 inches. By comparison, the conventional "thick-walled"
constructions of prior art multi-lumen catheters typically range in
thickness from about 0.003 to about 0.010 inches or more. For
purposes of this invention, the term "elongated" refers to catheter
apparatus or to sleeves having an overall length-to-diameter ratio
of about 25:1 or greater. In the embodiment of FIG. 1, if catheter
tube 12 is of conventional construction, tube 12 may provide
sufficient rigidity by itself for insertion of the apparatus into a
body canal or passageway. Alternatively, if inner catheter tube 12
is of very thin-walled construction, wire guide 13, previously
positioned using a guide catheter or other conventional manner, may
be needed in order to facilitate threading the catheter apparatus
through a blood vessel or similarly narrow passageway. Inner
catheter tube 12 may be of single or multi-lumen construction
depending on the number of channels desired for a particular
application. Catheter tube 12 may be configured open at both ends,
for example to fit over a wire guide 13, and to act as a channel to
inject or drain fluid, or to contain a diagnostic or therapeutic
device. Alternatively, tube 12 can also be sealed at its distal end
or configured in other advantageous ways.
[0044] Surrounding at least a portion of the length of inner
catheter tube 12 is a very thin-walled, inflatable and collapsible,
elongated inner sleeve 14 which may be, but need not be, at least
partially sealed at its distal end to the outer surface of tube 12
so as to create a second or intermediate lumen 16 comprising an
annual region with a donut-like cross section surrounding catheter
tube 12. The annular configuration of lumen 16 can be better
understood by reference to FIG. 2. For example, if tube 12 has an
external diameter of about 0.04 inches, sleeve 14 may comprise
biaxially-oriented polyethylene terephthalate (PET) and have an
inner diameter of about 0.087 inches and a sidewall thickness of
about 0.0005 inches. Surrounding at least a portion of the length
of sleeve 14 is a very thin-walled, inflatable and collapsible,
elongated outer sleeve 20 which is sealed at its distal end to the
outer surface of tube 12 at a point distal from the distal end of
sleeve 14 so as to create a third or outer lumen 22 comprising an
annular region with a donut-like cross section surrounding sleeve
14. The annular configuration of lumen 22 can be better understood
by reference to FIG. 2. In the preceding example, sleeve 20 may
comprise biaxially-oriented PET and have an inner diameter of about
0.125 inches and a sidewall thickness of about 0.00065 inches.
Fluid connection means 18, in this case comprising an opening
between the open distal end of sleeve 14 and the inner wall of
sleeve 20, places the distal end of lumen 16 in direct fluid
communication with the distal end of lumen 22. Alternatively, the
fluid connection means may comprise one or a plurality of apertures
in the common wall means (i.e. in sleeve 14) separating lumens 16
and 22. In the foregoing example, the total cross-sectional area
available for inlet and outlet fluid flow, as seen in FIG. 2,
represents approximately 87% of the available cross-sectional area
of the body canal in which the catheter apparatus is positioned.
For the heat transfer catheters of this invention, at least about
60%, and preferably greater than about 80% of the available
cross-sectional area of the body canal should be available for
fluid flow. Although lumens 16 and 22 are shown in FIG. 1 as single
lumens, it should be appreciated that one or both of these lumens
may be fabricated as a multi-lumen structure, but obviously with
some small associated loss of available fluid flow area because of
additional wall means.
[0045] Catheter apparatus 10 as shown in FIG. 1 further comprises a
first or proximal manifold section 30 and a second or distal
manifold section 32. The distal end of manifold 30 is adapted to
sealingly mate with the proximal end of manifold 32, for example by
means of male and female threaded elements, 34 and 36 respectively,
in combination with a resilient O-ring 38. Alternatively, manifolds
30 and 32 may be adhesively bonded to one another. Male element 34
of manifold 30 further comprises a centrally-located bore 40.
Manifold 30 also comprises a fluid inlet port 42 connected to a
source of fluid via a fluid fitting, which may also comprise an
inlet valve (not shown) or other fluid flow control means, and an
end seal 44. End seal 44 of manifold 30 also comprises a
centrally-located bore 46. Bore 46 is sized so as to receive
catheter tube 12. Fluid sealing means (not shown) are provided
between the outside of tube 12 and the surface of bore 46 to
prevent fluid leakage. Bore 40 is sized so as to receive both tube
12 and sleeve 14. The proximal end of sleeve 14 comprises fluid
sealing means, such as an annular lip or flange 15 projecting
radially outward and capable of being bonded or sealed to an inner
wall of manifold 30. Alternatively, the outside of the proximal end
of sleeve 14 may be adhesively bonded to the wall of bore 40.
[0046] Manifold 32 further comprises an outlet port 50, which may
comprise an outlet valve (not shown) or other fluid flow control
means, a tapered distal end 52 having a tubular projection 54, and
a centrally-located opening 56 passing through tapered end 52 and
projection 54. Opening 56 is sized so as to receive catheter tube
12 and sleeves 14 and 20 while leaving an open annular region
defined by the outside of sleeve 14 and the inside surface of
sleeve 20 through which fluid can pass. The outside of the proximal
end of sleeve 20 may be adhesively bonded to the wall of opening
56. Thus, after the distal portion of catheter apparatus 10 is
positioned in the body, fresh heat transfer fluid at a desired
temperature, ordinarily (but not necessarily) different from normal
body temperature, first enters manifold 30 through inlet port 42
(as illustrated by the fluid direction arrows), passes through the
interior cavity of manifold 30 into the proximal end of sleeve 14
at lip 15, then passes through inlet fluid lumen 16 to the distal
end of sleeve 14, then passes directly through fluid connection
means 18 into outlet fluid lumen 22, then passes back through lumen
22 to the proximal end of sleeve 20, then passes into the interior
of manifold 32 from which it exits through exit port 50. As used
herein, the term "inlet fluid lumen" means a passageway or conduit
of an elongated catheter through which fluid flow is substantially
in a direction from the proximal end toward the distal end.
Correspondingly, the term "outlet fluid lumen" means a passageway
or conduit of a catheter through which fluid flow is substantially
in a direction from the distal end toward the proximal end. The
spent heat transfer fluid exiting through port 50 may be recovered
and heated or cooled (as necessary) to restore it to the desired
temperature and then recycled back to inlet port 42.
[0047] The heat transfer fluids that are useful in the practice of
this invention include both gases and liquids, but are preferably
liquid. The fluid may be water or an aqueous solution, for example
normal saline, provided the desired heating or cooling temperature
is within the liquid range of water, i.e. about 0-100.degree. C.
For special applications, particularly for operating temperatures
below 0.degree. C. or above 100.degree. C., other fluids, such as
the various halogenated hydrocarbons (e.g. "Freon"), may be
utilized. Obviously the selected fluid must be one that will be
chemically compatible with the material from which the fluid lumens
are constructed at the desired operating temperature.
[0048] As illustrated in FIG. 1, manifold sections 30 and 32 may
comprise metal, plastic or other suitable materials. Catheter tube
12, inner sleeve 14 and outer sleeve 20 may comprise the same or
different thermoplastic materials. The choice of materials and
fabrication techniques may be adapted to meet particular design
specifications or to realize particular properties of the completed
apparatus. Some of the specific fabrication techniques, material
selections, and desirable design features that are within the scope
of this invention are presented below for purposes of illustration.
Other advantageous variations will be apparent to those skilled in
the art, and such obvious variations are also considered to be
within the scope of this invention.
[0049] With regard to sleeves 14 and 20, it is preferred that these
sleeves be of high tensile strength and able to withstand
anticipated internal fluid operating pressures, which, for some
applications, may be on the order of about 200 psi and higher,
while, at the same time, being sufficiently thin-walled to have
good heat transfer properties, to insure good contact with the
walls of the internal body cavity during use, and to minimize
wasted internal space. These sleeves should also be readily
inflatable under fluid pressure and readily collapsible under
vacuum to facilitate insertion and removal of the catheter
apparatus. To realize these combined objectives, sleeves 14 and 20
should have sidewalls not exceeding a thickness of about 0.002
inches, preferably less than about 0.001 inches, and, for some
embodiments, less than 0.0009 inches. Sleeves 14 and 20 can be
fabricated from an orientable polymeric material, for example using
tubing extrusion and blow molding techniques, such as those taught
in my copending U.S. patent application Ser. No. 08/059,725 and
Ser. No. 07/929,305. Biaxially-oriented PET sleeves can be prepared
as thin as 0.0002 inches, for example, while retaining adequate
tensile strength to insure against any ruptures while in use.
Because thicker walls of biaxially-oriented PET tend to be somewhat
rigid, it is preferred that such sleeves for this invention have
sidewall thicknesses ranging from about 0.0002-0.0009 inches. In an
alternative embodiment for certain applications, sleeves 14 and/or
20 may be fabricated from weaker but more flexible materials. For
example, polyurethane sleeves may have sidewalls as thick as about
0.005 inches while still retaining the necessary flexibility for
expansion, collapse, and conformity with the walls of the internal
body cavity while in use. It will be understood that, for any given
sleeve material, thinner sleeves will have better heat transfer
properties than thicker sleeves.
[0050] For most applications, including all dilatation
applications, it is preferred that fluid-carrying sleeves 14 and 20
be relatively inelastic. Fabrication of sleeves 14 and 20 from
biaxially-oriented PET, as discussed above for example, would yield
very thin-walled, high strength, relatively inelastic sleeves. Any
polymeric material capable of being oriented in at least one
direction with resultant enhancement of mechanical properties,
particularly strength, could be used to fabricate one or more of
the sleeves and catheters of this invention. Depending on the
specific apparatus construction and intended application, such
materials include PET, nylon, crosslinked polyethylene and ethylene
copolymers, urethanes, vinyls, and Teflon, among others. In some
applications, it may be preferred to fabricate outer sleeve 20, or
both sleeves 14 and 20 from an elastomeric material. One such
application would be where only relatively low fluid pressures are
needed, for example where the catheter apparatus does not include a
dilatation balloon and is not expected to be used in a dilatation
procedure. Another such application would be where variations in
internal anatomy would prevent an inelastic outer sleeve from
making good heat transfer contact with the walls of the internal
cavity or passageway.
[0051] If sleeves 14 and 20 are fabricated from PET, in addition to
containing a heat transfer fluid in accordance with this invention
these sleeves would also be capable of transmitting microwave
energy, Nd:YAG laser energy, UV laser energy, and others from the
proximal to the distal end of the apparatus. Also, if the fluid
carrying sleeves are fabricated from a suitable material, such as
biaxially-oriented PET or PTFE (Teflon), the catheter apparatus
would be capable of circulating cryogenic fluids for selective
freezing of tissue such as cancerous tumors. In this case, for
certain applications, it may be necessary to utilize multiple
lumens so as to combine heating of the catheter via this technology
along most of the length of the catheter while having the cryogenic
freezing occur only at a specific desired location at or near the
distal end of the catheter apparatus. The heating would prevent the
entire catheter from freezing, thereby damaging tissue areas that
should not be treated. For example, multiple lumens inside catheter
tube 12 could be used to circulate a cryogenic fluid while sleeves
14 and 20 contained a heating fluid to insulate adjacent tissue
along the length of the catheter except for the distal end beyond
the end of sleeve 20. In still another embodiment, the distal end
of tube 12 may communicate with a balloon element, which could then
also provide heating or cooling effects. Simultaneous selective
heating and cooling can also similarly be provided with the
catheter apparatus according to this invention; or, differential
heating br cooling can be provided where, for example, one side of
the catheter is hotter or cooler than the other side in order to
provide for treatment of asymmetric anatomical features.
Alternative embodiments of the catheter apparatus, as hereinafter
described, may also be adapted for such differential heating and/or
cooling applications.
[0052] In still another embodiment of this invention, the diameters
and wall thicknesses of tube 12 and of sleeves 14 and 20 may be
selected such that lumens 16 and 22 have substantially equal
cross-sectional areas for fluid flow. Alternatively, by adjusting
the diameters of one or more of tube 12, sleeve 14 and sleeve 20,
the cross-sectional areas of annular lumens 16 and 22 may be varied
to create different pressure gradients and fluid flow rates. In
another fabrication variation, sleeves 14 and 20 may be formed so
as to have substantially constant cross-sectional diameters along
their respective lengths at constant fluid pressure. Alternatively,
one or both of sleeves 14 and 20 may be formed so as to have
varying cross-sectional diameters along their lengths in order to
generate particular flow patterns, for example to cause turbulent
fluid flow at a desired location for purposes of increased heat
transfer.
[0053] FIG. 3 is a schematic, cross-sectional view of an
alternative embodiment of a heat transfer catheter in accordance
with this invention. In FIG. 3, catheter apparatus 60 comprises a
multi-lumen balloon dilatation catheter comprising a first or inner
sleeve 62, defining an open space or inner lumen 64, and a second
or outer sleeve 66 surrounding inner sleeve 62 so as to create an
outer annular lumen 68. Inner sleeve 62 is formed open at its
distal end and spaced from the inner wall of sleeve 66 so as to
create a fluid connection 70. Outer sleeve 66 is formed closed at
its distal end. The closed distal end of sleeve 66 is at a point
that is distal from the open distal end of sleeve 62 so that fluid
may pass through fluid connection means 70 from fluid inlet lumen
64 into fluid outlet lumen 68.
[0054] Proximate to its distal end, outer sleeve 66 comprises a
dilatation balloon segment 72. Balloon segment 72 is preferably of
very thin-wall, high strength construction, substantially
inelastic, and readily inflatable under fluid pressure and readily
collapsible under vacuum. In a preferred embodiment of this
variant, at least sleeve 66 and balloon segment 72 comprise a
unitary, integral and seamless unit wherein said sleeve portion and
said balloon segment are integrally formed in accordance with the
teachings of my copending U.S. patent application Ser. No.
08/059,725. In this embodiment of the invention, fresh heat
transfer fluid is introduced into the proximal end of inner lumen
64, passes through lumen 64 and fluid passage means 70 directly
into outer lumen 68, through the interior of balloon segment 72,
and then back along lumen 68 to the proximal end of the apparatus
where the spent fluid is withdrawn. During use, fluid flow control
means, such as valves, at the proximal ends of lumens 64 and 68 may
be used to maintain fluid pressure inside lumens 64 and 68 at a
level that is sufficient to fully inflate balloon segment 72.
Alternatively, a restriction can be incorporated into the manifold
so as to create pressure in the lumens.
[0055] The heat transfer balloon dilatation catheter apparatus of
FIG. 3 may be utilized in several different ways. In one
embodiment, lumens 64 and 68 may be partially inflated with fluid
in order to provide the stiffness needed to insert the catheter.
Once the apparatus is properly positioned, the fluid pressure may
be increased so as to fully inflate the dilatation balloon segment
72. Alternatively, a separate rod or hollow tube 74, as illustrated
in FIG. 3, can be inserted through inner lumen 64 to provide
stiffness. Tube 74 may be a solid rod or a hollow tube defining
another lumen 76. Tube 74 may also comprise an elongated diagnostic
or therapeutic device that is either permanently attached to the
catheter apparatus or is removable, so that the catheter apparatus
can be disposable and the medical instrument reusable or vice
versa. Examples of instruments that could be utilized in such a
combination catheter apparatus include microwave antennas, lasers,
ultrasound probes, induction coils, and electric heating
elements.
[0056] The requisite properties of sleeves 62 and 66 in FIG. 3, the
materials from which these sleeves are prepared, and the sleeve
fabrication techniques are similar to those discussed above for
sleeves 14 and 20 respectively in FIG. 1. Thus, sleeves 62 and 66,
including balloon segment 72, must have sufficient strength to
withstand anticipated internal fluid operating pressures while, at
the same time, being sufficiently thin-walled to have good heat
transfer properties, to insure good contact with the walls of the
internal body cavity during use, and to minimize wasted internal
space. These sleeves should also be readily inflatable under fluid
pressure and readily collapsible under vacuum. To realize these
combined objectives, sleeves 62 and 66, including balloon segment
72, generally have sidewalls not exceeding a thickness of about
0.002 inches. Similar to sleeves 14 and 20 in FIG. 1, sleeves 62
and 66 in FIG. 3 may be fabricated from an orientable polymeric
material, for example using tubing extrusion and blow molding
techniques. For this embodiment of the invention, sleeves 62 and 66
and, particularly, balloon segment 72, should be relatively
inelastic such that, when inflated and undeformed, balloon segment
72 dilates to a predetermined, repeatable size and shape.
Biaxially-oriented PET sleeves having sidewall thicknesses of about
0.0002-0.0009 inches are a particularly advantageous embodiment of
this version of the invention.
[0057] The heat transfer balloon dilatation catheter apparatus as
described above may further comprise one or a plurality of adjacent
lumens located externally of the maximum realizable dimension of
the inelastic balloon segment 72 and adjacent to the wall of the
balloon when the balloon is fully inflated and undeformed. In this
embodiment, the balloon segment shares with each said adjacent,
external lumen a single-layer, integrally formed wall section
comprising a portion of the balloon wall and separating the
interior of the balloon from the interior of the adjacent, external
lumen. The balloon comprises a very thin, flexible, high strength,
substantially inelastic material having a wall thickness of less
than about 0.0015 inches, preferably less than about 0.0009 inches.
The preparation and use of such multi-lumen balloon dilatation
catheters is taught in my copending U.S. patent application Ser.
No. 07/929,305.
[0058] FIGS. 4-6 illustrate one set of embodiments of a heat
transfer, multi-lumen balloon dilatation catheter apparatus
according to the present invention. FIG. 4 shows a
previously-formed heat transfer balloon dilatation catheter
apparatus 230, generally comparable to apparatus 60 of FIG. 3,
comprising an outer sleeve 232 (best seen in FIG. 5) having a
closed distal end 233 and a concentric, coaxial inner sleeve 234.
This structure is clearly evident in FIG. 5, a cross-sectional view
along the line 5-5 of FIG. 4. Outer sleeve 232 comprises a balloon
segment 236 having conical or tapered ends 238 and 240. Thus, in
one embodiment in accordance with this invention, the catheter
apparatus of FIG. 4 can be operated as a heat transfer catheter
comparable to FIG. 3, wherein heat transfer fluid enters through
the lumen defined by inner sleeve 234, dilates balloon segment 236,
and exits through the annular lumen defined between sleeves 232 and
234. Other embodiments utilizing the apparatus of FIG. 4, as
discussed below, are also contemplated, however. In accordance with
the technique described in U.S. Ser. No. 07/929,305, mandrels or
forming wires may be positioned along the external surface of outer
sleeve 232 and a tube 250 (best seen in FIG. 5) of a
heat-shrinkable thermoplastic thereafter shrunk around sleeve 232
so as to create one or more of adjacent, external lumens 242, 244,
and 246, each integrally formed with a portion of sleeve 232.
[0059] Fluid flow connection means, for example one or more
apertures, may be provided in the integrally formed wall means that
separates the interior of balloon segment 236 and one or more of
the adjacent, external lumens 242, 244 and 246. In this embodiment,
instead of having coaxial inner sleeve 234, fluid may be supplied
to balloon segment 236 through sleeve 232 and withdrawn through an
externally-extending adjacent, external lumen such as lumen 242. As
seen in FIG. 4, external, adjacent lumen 242 can be formed so as to
run the entire length of sleeve 232, including balloon segment 236
and conical ends 238 and 240. Thus, in still another embodiment of
this invention, an apparatus similar to that shown in FIG. 4 but
having two perimetrical lumens like lumen 242 running the entire
length of sleeve 232 could be used to deliver heat transfer fluid
to a body location distal of balloon segment 236. The flow of heat
transfer fluid, in through one of said perimetrical lumens and out
through the other, would not be significantly interrupted even
during dilatation of balloon segment 236. Similarly, and for other
applications, external, adjacent lumen 244 can be formed so as to
run from one end of the middle or working section of balloon 236 to
the other. Similarly, external, adjacent lumen 246 can be formed so
as to begin and end within the working section of balloon 236. By
proper selection of the forming wires, external, adjacent lumens
can be created of the same or different diameters, of uniform or
non-uniform cross-section, and of circular or other cross-sectional
shape, as desired for particular applications. Employing a similar
preparation technique, a heat transfer balloon dilatation catheter
apparatus can be prepared as shown in FIG. 6 wherein an external,
adjacent lumen 252 runs in a helical pattern around the outside
wall of balloon 236. Helical lumen 252 may comprise, in one
embodiment, a plurality of pinholes 254 along its length to
precisely deliver medication or other fluids to select body
locations.
[0060] FIGS. 7 and 8 illustrate alternative embodiments of a heat
transfer, multi-lumen balloon dilatation catheter apparatus
according to the present invention. The preparation and use of
multi-lumen balloons having cross-sectional configurations similar
to those shown in FIGS. 7 and 8 is also taught in my copending U.S.
patent application Ser. No. 07/929,305. Thus, the nine-lumen
balloon structure of FIG. 7 is prepared either by heat-shrinking a
thermoplastic sleeve over the four-lobe interior structure (which,
in turn, is made by blow molding a five-lumen extruded preform) or
by blow molding a five-lumen extruded preform inside a
thermoplastic sleeve.
[0061] In FIG. 7, one or more of lumens 126, 127, 128 and 130, for
example, could be utilized as inlet lumens for heat transfer fluid,
and one or more of lumens 134, 135, 136 and 138 could be utilized
as outlet lumens for heat transfer fluid, by providing fluid
connection means between adjacent inlet and outlet lumens. For
example, lumen 126 could be provided with apertures in its sidewall
to permit fluid flow into one or both of adjacent lumens 134 and
138. Correspondingly, lumen 130 could be provided with apertures in
its sidewall to permit fluid flow into one or both of adjacent
lumens 135 and 136. In this example, inlet lumen 126 and outlet
lumens 134 and 138 could carry heat transfer fluid at a first
temperature, while inlet lumen 130 and outlet lumens 135 and 136
could carry heat transfer fluid at a second, different temperature.
Those lumens not being utilized to circulate heat transfer fluid,
such as central lumen 124 and side lumens 127 and 128 in the above
example, could be utilized to enclose a medical instrument, a guide
wire, or the like, or to provide fluid passageways for medicine
delivery, fluid drainage, or perfusion applications. Although FIG.
7 illustrates a multi-lumen dilatation balloon having nine lumens,
at least two of which must be interconnected to provide fluid flow
in accordance with the present invention, it will be understood
that similar preparation techniques could be used to prepare
similar multi-lumen balloon structures having more or fewer lumens
than nine.
[0062] The structure of FIG. 8 is prepared by blow molding a
nine-lumen extruded preform of appropriate starting geometry, also
as described in Ser. No. 07/929,305. Similar to FIG. 7, FIG. 8
illustrates a nine-lumen balloon structure in which one or more of
lumens 426, 427, 428 and 430, for example, could be utilized as
inlet lumens for heat transfer fluid, and one or more of lumens
134, 135, 136 and 138 could be utilized as outlet lumens for heat
transfer fluid, by providing fluid connection means between
adjacent inlet and outlet lumens. For example, lumen 427 could be
provided with apertures in its sidewall to permit fluid flow into
one or both of adjacent lumens 434 and 435. Correspondingly, lumen
428 could be provided with apertures in its sidewall to permit
fluid flow into one or both of adjacent lumens 436 and 438. In this
example, inlet lumen 427 and outlet lumens 434 and 435 could carry
heat transfer fluid at a first temperature, while inlet lumen 428
and outlet lumens 436 and 438 could carry heat transfer fluid at a
second, different temperature. As discussed above with respect to
FIG. 7, those lumens not being utilized to circulate heat transfer
fluid could be utilized for other applications. It will be
understood that similar preparation techniques could be used to
prepare similar multi-lumen balloon structures having more or fewer
lumens than nine.
[0063] FIG. 9 illustrates yet another embodiment of this invention.
In FIG. 9, catheter apparatus 80 comprises two concentric, coaxial
lumens consisting of an inner inlet lumen and an outer outlet
lumen. The inner inlet lumen 82 defined by inner sleeve 84 is
surrounded by a closed-end outer sleeve 86 of larger diameter than
inner sleeve 84 thereby defining an annular outlet lumen 88 having
a donut-like cross section. Inner sleeve 84 includes fluid
communication means, such as multiple apertures or side holes 90
which permit fluid to pass directly from inlet lumen 82 to outlet
lumen 88 at or near the distal end of inlet lumen 82. The proximal
end of inlet lumen 82 is coupled to fluid inlet means 83, for
example a one-way valve. Correspondingly, the proximal end of
outlet lumen 88 is coupled to fluid outlet means 89, for example a
one-way valve. Housing means 85 may be provided to facilitate
coupling the inlet and outlet lumens to their respective inlet and
outlet valves.
[0064] Similar to the embodiment shown in FIG. 3, the catheter
apparatus of FIG. 9 may be filled with fluid and pressurized in
order to stiffen it sufficiently to facilitate insertion or,
alternatively, a solid rod or hollow tube (not shown) can be
inserted into one of the lumens to provide the necessary stiffness.
Instead of a rod or tube, an elongated diagnostic or therapeutic
device may be used to provide stiffness. Such device may either be
permanently attached to the catheter apparatus or it may be
removable, so that the catheter apparatus can be disposable and the
medical device reusable or vice versa.
[0065] FIGS. 1-6 and 9 as discussed above illustrate embodiments of
this invention in which the heat transfer fluid inlet and outlet
lumens are concentric and coaxial. This configuration is relatively
easy to manufacture and generally permits maximum fluid flow for
any given external catheter diameter because a single-layer wall
means (for example, sleeve 14 in FIGS. 1 and 2, sleeve 62 in FIG.
3, sleeve 234 in FIG. 5, and sleeve 84 in FIG. 9) can serve as both
the outer wall of an inner inlet lumen and as the inner wall of an
outer, annular-shaped outlet lumen. Other configurations of inlet
and outlet lumens, however, are also within the scope of this
invention. FIGS. 7 and 8 illustrate two embodiments wherein the
inlet and outlet lumens are not in a concentric, coaxial
configuration. Another such alternative configuration is
illustrated in FIG. 10.
[0066] FIG. 10 is a schematic cross-sectional view of a different
lumen configuration for another heat transfer catheter 100 in
accordance with this invention. In FIG. 10, outer sleeve 102
surrounds and encloses two inner sleeves 104 and 106 of smaller
diameter which define respectively lumens 108 and 110. Also shown
in FIG. 10, enclosed within outer sleeve 102 but external of lumens
108 and 110, is a central longitudinal member 112 which may, in
alternative embodiments, comprise a rod, a hollow tube, or a
diagnostic or therapeutic instrument, or a combination of one or
more. If, as illustrated in FIG. 10, sleeves 104 and 106 and member
112 are of such size and geometry as to not fill all of the
interior space enclosed by outer sleeve 102, upon fluid inflation
an irregularly shaped lumen 114 would also be created inside sleeve
102. Thus, in this embodiment, lumens 108 and 110 could be utilized
as fluid inlet lumens for introducing heat transfer fluid to
catheter apparatus 100, and lumen 114 utilized as the fluid outlet
lumen. Fluid connection means (not shown), such as holes or
apertures in sleeves 104 and 106, are provided to establish a flow
of the heat exchange fluid from inlet lumens 108 and 110 to outlet
lumen 114.
[0067] The catheter configuration illustrated in FIG. 10
facilitates a number of advantageous variations on the basic
invention. For example, the catheter apparatus 100 of FIG. 10 can,
similar to the embodiments of FIGS. 7 and 8, provide heat transfer
fluid at two different temperatures, for example one for selective
heating, the other for selective cooling. Different fluid flow
rates can also be established in inlet lumens 108 and 110. Inner
sleeves 104 and 106 may be either of the same or different
diameters, wall thicknesses, and materials. By making one of the
inner sleeves of a larger diameter than the other, upon fluid
inflation member 112 will be displaced off-center and moved closer
to one side of the inner wall of sleeve 102 than the other side.
This embodiment may be useful where member 112 is a medical
instrument. A similar result could be achieved by selectively
inflating only one of the two inner sleeves 104 and 106.
[0068] It will be understood that a catheter apparatus according to
this invention as illustrated in FIG. 10 could be prepared with
only one inner sleeve (i.e. only one fluid inlet lumen) or,
alternatively, with three, four or more inner sleeves instead of
the two shown. It will also be understood that for any of the
catheter apparatuses within the scope of this invention the heat
transfer inlet and outlet lumens can be configured to run
substantially the entire working length of the catheter or to
occupy only a discrete, predetermined portion of the catheter. For
example, the heat transfer inlet and outlet lumens may commence at
the point where the catheter enters the body and terminate at a
location intermediate of the distal end of the catheter.
Alternatively, the heat transfer inlet and outlet lumens may be
defined by conventional "thick-walled" sidewalls along a proximal
section of the catheter, and defined by very thin sidewalls of
about 0.0002-0.002 inches thickness only along a distal section of
the catheter. In this construction, heat transfer would be
minimized along the proximal, thick-walled section of the catheter
and maximized at the thin-walled distal end.
[0069] Since certain changes may be made in the above-described
apparatuses and processes without departing from the scope of the
invention herein involved, it is intended that all matter contained
in the above description shall be interpreted in an illustrative
and not in a limiting sense.
* * * * *