US 20080177231 A1
Heat transfer catheter apparatus and methods of making and using the 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.
1: 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 to circulate a working fluid; and
(c) a second lumen external and adjacent to said substantially elongate shaft, said second lumen having a spiral shape.
This application is a continuation of U.S. application Ser. No. 11/017,710, filed Dec. 22, 2004, which is a continuation of U.S. application Ser. No. 10/184,889, filed Jul. 1, 2002, which is a continuation of U.S. application Ser. No. 09/309,052, filed May 10, 1999, now U.S. Pat. No. 6,440,158, which is a division of U.S. application Ser. No. 08/453,066, filed May 26, 1995, now U.S. Pat. No. 5,902,268, which is a division of U.S. application Ser. No. 08/287,114, filed Aug. 8, 1994, now U.S. Pat. No. 5,342,392, which is a continuation-in-part of (a) U.S. patent application Ser. No. 08/059,725, filed May 10, 1993, now U.S. Pat. No. 5,411,477, which in turn was a continuation of U.S. patent application Ser. No. 07/522,178, filed May 11, 1990, now abandoned, and (b) of U.S. application Ser. No. 07/929,305, filed Aug. 13, 1992, now U.S. Pat. No. 5,342,301. The disclosures of these above identified applications are incorporated herein by reference.
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. No. 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.
U.S. Pat. No. 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.
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 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.).
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 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.
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.
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. No. 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.
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. 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).
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 art catheters in connection with heat transfer applications are overcome with the heat transfer catheters of this 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.
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.
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.
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
Catheter apparatus 10 as shown in
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.
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.
As illustrated in
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.
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.
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.
The heat transfer balloon dilatation catheter apparatus of
The requisite properties of sleeves 62 and 66 in
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.
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
The structure of
Similar to the embodiment shown in
The catheter configuration illustrated in
It will be understood that a catheter apparatus according to this invention as illustrated in
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.