Heat transfer catheters and methods of making and using same

Heat transfer catheter apparatus and methods of making and using same are disclosed wherein fluid connection means 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.

BACKGROUND OF THE INVENTION 
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. 
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. 
Typical of the prior art in this field are U.S. Pat. Nos. 4,646,722 
(Silverstein et al.) and 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. 
U.S. Pat. Nos. 3,794,091 (Ersek et al.) and 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. 
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 3-4 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. 
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 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), No. 4,422,447 (Schiff), and No. 4,681,092 (Cho et 
al.). 
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. 
It is also known, as shown in U.S. Pat. No. 4,299,226 (Banka) and 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 styler 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. 
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. Nos. 
4,994,033 (Shockey et al.) and 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. 
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. 
U.S. Pat. Nos. 4,581,017 (Sahota) and 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. 
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. 
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. Pat. No. 5,342,301 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 U.S. Pat. No. 5,342,301 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). 
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. 
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. 
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. 
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. 
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. 
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. 
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. 
These and other problems with and limitations of the prior an catheters in 
connection with heat transfer applications are overcome with the heat 
transfer catheters of this invention. 
OBJECTS OF THE INVENTION 
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. 
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. 
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. 
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. 
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. 
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. 
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. 
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 
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.

DETAILED DESCRIPTION OF THE INVENTION 
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. 
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. 
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. 
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, such as reservoir 43, of fluid via a fluid 
fitting, which may also comprise an inlet valve 41 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. 
Manifold 32 further comprises an outlet port 50, which may comprise an 
outlet valve 51 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), for example with a 
conventional heating or cooling jacket 45 surrounding fluid reservoir 43, 
to restore it to the desired temperature and then recycled back to inlet 
port 42. 
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.degree.-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. 
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. 
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 
U.S. Pat. Nos. 5,411,477 and 5,342,301. 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. 
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. 
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 or 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. 
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. 
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. 
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 U.S. Pat. No. 5,411,477. 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. 
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. 
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 fully 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. 
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 U.S. Pat. No. 5,342,301. 
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. Pat. No. 5,342,301, 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. 
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. 
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 U.S. Pat. No. 5,342,301. 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. 
FIG. 7 shows a multi-lumen balloon 122 in accordance with this alternative 
embodiment of the present invention. In this design, the catheter shaft 
124 is of a conventional design, except that it does not have to be 
provided with lumens for allowing for fluid flow when the balloon is 
inflated. Instead the balloon is formed as a multi-lumen balloon in 
accordance with my U.S. Pat. No. 5,342,301 for providing the necessary 
fluid flow, and for providing the necessary inflation so as to achieve 
dilatation of a selected body passageway. As seen in FIG. 7, center lumen 
132 receives the catheter shaft 124 so that the balloon can be secured in 
place with a suitable adhesive to the shaft. At least four lumens 126, 
127, 128 and 130 are radially spaced around center lumen 132 for receiving 
the pressurized fluid for inflating each of these lumens so as to achieve 
dilatation. The lumens 126, 127, 128 and 130, must be closed or connected 
and be adapted to be in fluid communication with a source of pressurized 
fluid. Lumens 134, 135, 136 and 138, are formed within the spaces between 
lumens 126, 127, 128 and 130, and the corresponding wall sections 140, 
143, 142 and 144, when lumens 126, 127, 128 and 130 are inflated. 
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. 
The structure of FIG. 8 is prepared by blow molding a nine-lumen extruded 
preform of appropriate starting geometry, also as described in U.S. Pat. 
No. 5,342,301. 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 434, 435, 436 and 438 could be utilized as outlet 
lumens for heat transfer fluid, by providing fluid connection means 
between adjacent inlet and outlet lumens. In FIG. 8, reference numerals 
422, 424, 432, 440, 442, 443, and 444 refer respectively to the comparable 
structural elements as in FIG. 7, namely reference numerals 422/122 
(multi-lumen balloon); 424/124 (catheter shaft); 432/132 (center lumen); 
and 440/140, 442/142, 443/143, and 444/144 (wall sections). 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. 
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. 
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. 
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. 
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. 
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. 
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. 
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.