Medical catheter for hypothermic treatment, treatment system with such a catheter, and production method

Abstract

A medical catheter for hypothermic treatment with a catheter tube has at least one through-channel and at least two temperature control channels, at least one heat exchange element, in particular an expandable balloon, which is arranged in a distal catheter portion of the catheter tube and is fluidically connected to the temperature control channels in such a way that a temperature control circuit is formed. The catheter tube has a smaller external diameter in the distal catheter portion than in a proximal catheter portion.

Claims

1. A medical catheter for hypothermic treatment; the medical catheter comprising: a catheter tube comprising arranged in an axial direction of the catheter tube, a proximal catheter portion, a distal catheter portion, and a heat-exchanger element disposed in its entirety at a distal portion of the distal catheter portion, a first outside diameter in the distal catheter portion and a second outside diameter in the proximal catheter portion, the first outside diameter being smaller than the second outside diameter, a first bending flexibility at the distal catheter portion and a second bending flexibility at the proximal catheter portion, the first bending flexibility is greater than the second bending flexibility, a through-lumen, and at least two temperature-regulating lumens; the heat-exchanger element in fluid communication with the at least two temperature-regulating lumens; and a temperature-regulating circuit comprising the heat-exchanger element and the at least two temperature-regulating lumens; wherein the heat-exchanger element comprises a compressed state, wherein the heat-exchanger element in the compressed state comprises a cross-sectional diameter equal to or smaller than the second outside diameter of the proximal catheter portion; wherein the at least two temperature-regulating lumens comprise a first cross-sectional area in the proximal catheter portion and a second cross-sectional area in the distal catheter portion; and wherein the first cross-sectional area is larger than the second cross-sectional area.

2. The medical catheter of claim 1, further comprising a first wall thickness of the catheter tube in the distal catheter portion and a second wall thickness of the catheter tube in the proximal catheter portion, the first wall thickness being smaller than the second wall thickness.

3. The medical catheter of claim 1, further comprising a receiving space for receiving the heat-exchanger element, the receiving space being formed on the distal catheter portion between a first outer peripheral level of the distal catheter portion and a second outer peripheral level of the proximal catheter portion, the heat-exchanger element in the compressed state is disposed completely inside the receiving space.

4. The medical catheter of claim 1, wherein the catheter tube comprises a unitary structure.

5. The medical catheter of claim 1, wherein the catheter tube comprises two-layer outer wall in the proximal catheter portion.

6. The medical catheter of claim 5, wherein the outer wall comprises, in the proximal catheter portion, an inner layer and an outer layer or, in the distal catheter portion, the inner layer.

7. The medical catheter of claim 6, wherein the inner layer or the outer layer comprises a porous structure or hollow spheres.

8. The medical catheter of claim 6, wherein the outer layer comprises a thermal conductivity of at most 0.2 Wm.sup.1K.sup.1.

9. The medical catheter of claim 1, wherein the catheter tube comprises an outer tube and an inner tube, the outer tube being larger than the inner tube; further comprising an insulating space formed between the outer tube and the inner tube.

10. The medical catheter of claim 9, wherein the outer tube and the inner tube being aligned eccentrically relative to one another.

11. The medical catheter of claim 9, further comprising a spacer is disposed between the outer tube and the inner tube proximal to the at least two temperature-regulating lumens.

12. The medical catheter of claim 11, wherein the spacer is formed by shaping the axial end of the outer tube.

13. The medical catheter of claim 9, wherein the outer wall of the catheter tube comprises a wall thickness that is constant.

14. The medical catheter of claim 1, wherein the catheter tube comprises a catheter tip at a distal axial end of the catheter tube, the catheter tip comprising a first cross-sectional diameter, the distal catheter portion comprising a second cross-sectional diameter; wherein the first cross-sectional diameter is larger than the second cross-sectional diameter.

15. The medical catheter of claim 1, wherein each of the at least two temperature-regulating lumens respectively comprise a cross-sectional profile in a shape of a pulmonary lobe.

16. The medical catheter of claim 1, wherein the through-lumen and the at least two temperature-regulating lumens are separated by an inner wall, the inner wall being flexible to vary respective cross-sectional areas of the at least two temperature-regulating lumens.

17. The medical catheter of claim 1, further comprising a receiving region for a medical instrument is disposed in the distal catheter portion, the receiving region comprising a first cross-sectional diameter and the through-lumen comprising a second cross-sectional diameter, the first cross-sectional diameter is larger than the second cross-section diameter.

18. The medical catheter of claim 1, wherein the catheter tube comprises a catheter tip, wherein only the through-lumen extends through the catheter tip.

19. A treatment system comprising: a medical catheter for hypothermic treatment; the medical catheter comprising: a catheter tube comprising a proximal catheter portion and a distal catheter portion, a first outside diameter in the distal catheter portion and a second outside diameter in the proximal catheter portion, the first outside diameter being smaller than the second outside diameter, a through-lumen, and at least two temperature-regulating lumens; a heat-exchanger element disposed in its entirety in the distal catheter portion and being in fluid communication with the at least two temperature-regulating lumens; and a temperature-regulating circuit comprising a heat-exchanger element and the at least two temperature-regulating lumens; and a self-expandable device joined to an elongated guide element, the self-expandable device being longitudinally displaceable together with the guide element, the self-expandable device being longitudinally displaceable together with the guide element in the through-lumen; wherein the heat-exchanger element comprises a compressed state, wherein the heat-exchanger element in the compressed state comprises a cross-sectional diameter equal to or smaller than the second outside diameter of the proximal catheter portion; wherein the catheter tube comprises a first bending flexibility at the distal catheter portion and a second bending flexibility at the proximal catheter portion, the first bending flexibility is greater than the second bending flexibility; wherein the at least two temperature-regulating lumens comprise a first cross-sectional area in the proximal catheter portion and a second cross-sectional area in the distal catheter portion; and wherein the first cross-sectional area is larger than the second cross-sectional area.

20. The treatment system of claim 19, further comprising a microcatheter and a guide catheter; wherein the self-expandable device is disposed displaceably in the microcatheter, the microcatheter being longitudinally displaceably inside the guide catheter.

21. The treatment system of claim 19, further comprising a guide catheter, the guide catheter is longitudinally displaceable in the through-lumen.

22. A method for making a medical catheter, the medical catheter for hypothermic treatment; the medical catheter comprising: a catheter tube comprising a proximal catheter portion and a distal catheter portion, a first outside diameter in the distal catheter portion and a second outside diameter in the proximal catheter portion, the first outside diameter being smaller than the second outside diameter, a through-lumen, and at least two temperature-regulating lumens; a heat-exchanger element disposed in the distal catheter portion and being in fluid communication with the at least two temperature-regulating lumens; and a temperature-regulating circuit comprising a heat-exchanger element and the at least two temperature-regulating lumens; the method comprising the step of: forming the catheter tube in one piece from a single material or from several different materials by an extrusion process; wherein the heat-exchanger element comprises a compressed state, wherein the heat-exchanger element in the compressed state comprises a cross-sectional diameter equal to or smaller than the second outside diameter of the proximal catheter portion; wherein the catheter tube comprises a first bending flexibility at the distal catheter portion and a second bending flexibility at the proximal catheter portion, the first bending flexibility is greater than the second bending flexibility; wherein the at least two temperature-regulating lumens comprise a first cross-sectional area in the proximal catheter portion and a second cross-sectional area in the distal catheter portion; and wherein the first cross-sectional area is larger than the second cross-sectional area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in more detail hereinafter on the basis of exemplary embodiments with reference to the attached schematic drawings, wherein

(2) FIG. 1 shows a longitudinal section through the catheter tube of an inventive catheter according to a preferred exemplary embodiment;

(3) FIG. 2 shows a cross section through the catheter tube according to FIG. 1 in the proximal catheter portion;

(4) FIG. 3 shows a cross section through the catheter tube according to FIG. 2 in the distal catheter portion;

(5) FIG. 4 Shows a schematic side view of the catheter tube according to FIG. 1;

(6) FIG. 5 shows a cross section through a proximal catheter portion of a one-piece catheter tube;

(7) FIG. 6 shows a cross section through the proximal catheter portion of a multi-layer catheter tube;

(8) FIG. 7 shows a cross section through the proximal catheter portion of a multi-layer catheter tube, wherein spacers are provided to form an insulating space;

(9) FIG. 8 shows a cross section through a proximal catheter portion of a catheter tube, wherein an annular, continuous insulating space is provided between an outer tube and an inner tube;

(10) FIG. 9 shows a longitudinal-sectional view through the catheter tube according to FIG. 8;

(11) FIG. 10 shows a cross-sectional view through the proximal catheter portion of an inventive medical catheter according to a further preferred exemplary embodiment, wherein the catheter tube has an inner tube and an eccentrically disposed outer tube;

(12) FIG. 11 shows a cross-sectional view through a further catheter tube with an inner tube and an outer tube, wherein spacers are disposed between the inner tube and the outer tube;

(13) FIG. 12 shows a cross-sectional view through the distal catheter portion of a catheter tube according to FIGS. 5 to 11;

(14) FIG. 13 shows a longitudinal-sectional view through a catheter tube of the inventive catheter according to a further preferred exemplary embodiment, wherein the temperature-regulating volume in the proximal catheter portion have a larger cross-sectional area than in the distal catheter portion;

(15) FIG. 14 shows a longitudinal-sectional view through an inventive catheter according to a further preferred exemplary embodiment with a catheter tip disposed at the distal axial end, wherein a balloon in the compressed condition is disposed as the heat-exchanger element between the catheter tip and the proximal catheter portion;

(16) FIG. 15 shows the longitudinal-sectional view according to FIG. 14, wherein the balloon is displayed in expanded condition;

(17) FIG. 16a shows a side view of a catheter tube of the inventive catheter according to a preferred exemplary embodiment;

(18) FIG. 16b and FIG. 16c respectively show a cross-sectional view through the catheter tube according to FIG. 16;

(19) FIG. 17a shows a longitudinal-sectional view through a catheter tube of an inventive catheter according to a further preferred exemplary embodiment with a dilator disposed in the through-lumen;

(20) FIG. 17b shows a cross-sectional view of the catheter tube according to FIG. 17a, with the section line marked;

(21) FIG. 17c and FIG. 17d respectively show a cross-sectional view through the catheter tube according to FIG. 17a;

(22) FIG. 17e shows a cross-sectional view through the dilator according to FIG. 17a;

(23) FIG. 18a shows a longitudinal-sectional view through a catheter tube of the catheter according to FIG. 17a;

(24) FIG. 18b shows a cross-sectional view through the catheter tube according to FIG. 18a, with the section line marked;

(25) FIG. 19a shows a further longitudinal-sectional view through the catheter tube according to FIG. 18a;

(26) FIG. 19b shows a further cross-sectional view through the catheter tube according to FIG. 19a, with the section line marked.

DETAILED DESCRIPTION OF THE INVENTION

(27) FIG. 1 shows a catheter tube 10 of an inventive catheter, wherein catheter tube 10 has a proximal catheter portion 15 and a distal catheter portion 16. Distal catheter portion 16 comprises a catheter tip 18. In distal catheter portion 16, a heat-exchanger element 14 is disposed proximal to catheter tip 18. Heat-exchanger element 14 is preferably designed as an expandable balloon.

(28) FIG. 2 shows a cross section through catheter tube 10 according to FIG. 1 in the transition region between catheter tip 18 and the part of distal catheter portion 16 supporting heat-exchanger element 14. In principle, the catheter tube has, in distal catheter portion 16, especially also in the region of heat-exchanger element 14, a cross section according to FIG. 2.

(29) Catheter tube 10 has on the whole an outer wall 20, which bounds catheter tube 10 on the outside. At the same time, outer wall 20 forms a boundary for three lumens 11, 12, 13, which extend longitudinally axially through catheter tube 10. In particular, catheter tube 10 has a through-lumen 11, which extends completely through catheter tube 10. Through-lumen 11 has circular cross section. Preferably through-lumen 11 is used as an instrument lumen, i.e. for advancing instruments through catheter tube 10 to a point of treatment. Such instruments may comprise, for example, a recanalization device or in general a self-expandable element. Through-lumen 11 is disposed eccentrically relative to the longitudinal axis of catheter tube 10.

(30) Furthermore, catheter tube 10 is provided with two temperature-regulating lumens 12, 13. The temperature-regulating lumens not only are bounded by outer wall 20 but also are separated from one another and from through-lumen 11 by an inner wall 19. Inner wall 19 extends through the catheter tube and preferably has a Y-shaped cross section. Temperature-regulating lumens 12, 13 respectively have cross sections resembling pulmonary lobes.

(31) The longitudinal section according to FIG. 1 cuts through through-lumen 11 and inner wall 19, and so the temperature-regulating lumens are not visible in FIG. 1. In contrast, the balloon forming heat-exchanger element 14 is clearly visible in FIG. 1. Heat exchanger element 14 is compressed or collapsed and thus increases the outside dimensions of catheter tube 10 in regions of distal catheter portion 16. Moreover, it can be clearly seen in FIG. 1 that catheter tube 10 has a smaller cross-sectional diameter in distal catheter portion 16 than in proximal catheter portion 15. In this way, within distal catheter portion 16, sufficient space outside the catheter tube is created in radial direction relative to catheter tube 10 in order to receive the compressed balloon or compressed heat-exchanger element 14. Specifically, heat-exchanger element in the compressed or collapsed condition has on the whole outside dimensions that are not larger than the cross-sectional diameter or the outside dimensions of catheter tube 10 in proximal catheter portion 15. Thus heat-exchanger element 14, when in compressed or collapsed condition, may have an outside dimension that is smaller than or at most just as large as the outside dimension of proximal catheter portion 15.

(32) In general, it may be provided that inner wall 19 is flexible. In particular, several flexible inner walls 19 separating individual lumens 11, 12, 13 from one another may be disposed inside catheter tube 10. Because of the flexibility of the inner walls, temperature-regulating lumens 12, 13 are able to dilate, in order to permit a higher volume flow of a temperature-regulating fluid. To guide an instrument through through-lumen 11, it is possible to compress temperature-regulating lumens 12, 13, for example by creating a partial vacuum, so that through-lumen 11 is correspondingly widened. It is preferable when the inner walls of catheter tube 10 are sufficiently stable that deformation of through-lumen 11 and/or of temperature-regulating lumens 12, 13 is prevented. Nevertheless, catheter tube 10 preferably has high bending flexibility.

(33) Alternatively or additionally, a receiving region adapted to receive a medical instrument, especially an expanded instrument, may be provided in distal catheter portion 16. The receiving region preferably has a cross-sectional area larger than the cross-sectional area of through-lumen 11. In particular, inner wall 19 may end at a distance from the distal end of catheter tube 10, so that catheter tube 10 is substantially free of internals in the receiving region.

(34) Furthermore, it can be seen in FIG. 1 that the wall thickness of outer wall 20 is larger in proximal catheter portion 15 than in distal catheter portion 16. At the same time, outer wall 20 functions as an insulating member, so that temperature losses in proximal catheter portion 15 are prevented while a temperature-regulating fluid is flowing through it.

(35) As regards catheter tip 18, it is provided that is has a conical geometry. The conical geometry of catheter tip 18 may be asymmetric, so that a through hole 27, which extends through catheter tip 18, is linearly aligned with through-lumen 11. In the exemplary embodiment according to FIG. 1, catheter tip 18 has an outside diameter that at most corresponds to the outside diameter of distal catheter portion 16.

(36) FIG. 3 shows a further cross section through catheter tube 10 according to FIG. 1. A cross section through distal catheter portion 16 containing heat-exchanger element 14 is illustrated. It is readily visible that outer wall 20 has a larger outside diameter in proximal catheter portion 15 than does outer wall 20 in distal catheter portion 16. Specifically, outer wall 20 in proximal catheter portion 15 forms a cylindrical proximal outer peripheral level 28. In distal catheter portion 16, outer wall 20 forms a distal outer peripheral level 29. An annular receiving space 17 is formed between proximal outer peripheral level 28 and distal outer peripheral level 29. Compressed or collapsed heat-exchanger element 14 is disposed inside receiving space 17, which is bounded radially inwardly by distal outer peripheral level 29 and radially outwardly by proximal outer-peripheral level 28. In other words, heat exchanger element 14 or the balloon may be sufficiently compressible or foldable that heat-exchanger element 14 can be disposed completely inside receiving space 17.

(37) It is expedient when heat-exchanger element 14 in the compressed or collapsed condition does not protrude radially outward beyond proximal outer peripheral level 28. To the contrary, proximal outer peripheral level 28 of outer wall 20 in proximal catheter portion 15 forms the largest cross-sectional diameter of the entire catheter tube 10. The compressed or collapsed condition is preferably achieved or maintained by application of external forces. For example, a sheath in which catheter tube 10 is disposed may form a boundary, which prevents expansion of heat-exchanger element 14, especially of a balloon.

(38) As regards heat-exchanger element 14, it is preferably provided that this is formed by an expandable balloon. On the one hand the balloon may be collapsed to compressed condition, but when filled with a temperature-regulating fluid may be dilated to its nominal size. Such a balloon is produced in the widened or expanded condition and is compressed by collapsing it. The balloon therefore exhibits non-compliant behavior. In this connection, the cross-sectional diameter of the balloon increases at a relative internal pressure of 2 bar by at most 10%, especially at most 5%, especially at most 2.5%, especially at most 1% compared with the fully expanded condition of the balloon (relative internal pressure approximately 0.1 bar to 0.2 bar). Alternatively, a so-called compliant balloon comprising an elastic material may be used. Such balloons are produced in the compressed condition. The elastic balloon is dilated radially by a fluid pressure and shrinks to the original nominal size upon relaxation of the fluid pressure.

(39) In general, heat-exchanger element 14 or the balloon is in fluidic communication with temperature-regulating lumens 12, 13. For this purpose, outer wall 20 preferably has two fluid openings 33, 34, wherein each of the two fluid openings 33, 34 is respectively allocated to a temperature-regulating lumen 12, 13. Both fluid openings 33, 34 discharge into the balloon or heat-exchanger element 14. On the whole, a temperature-regulating circuit is established in this way. In this case a first temperature-regulating lumen 12 may form a fluid-supply line and a second temperature-regulating lumen 13 a fluid-return line. Temperature-regulating fluid, preferably a cooling medium, may flow via first temperature-regulating lumen 12 to heat-exchanger element 14 or balloon. The temperature-regulating fluid flows through the balloon, preferably from distally to proximally, and passes via a proximal fluid opening 34 in outer wall 20 into second temperature-regulating lumen 13. Via a second temperature-regulating lumen 13 or the fluid-return line, the temperature-regulating fluid is discharged from catheter tube 10.

(40) The principle of the invention is schematically illustrated once again in FIG. 4. Catheter tube 10, illustrated in simplified form, generally has a proximal catheter portion 15 and a distal catheter portion 16. A collapsed balloon is disposed as heat-exchanger element 14 in distal catheter portion 16. The balloon or heat-exchanger element 14 is supported by distal catheter portion 16 of catheter tube 10. Specifically, heat-exchanger element 14 in collapsed condition is arranged in such a way that it is disposed inside a receiving space 17, which is bounded in radial direction on the one hand by proximal outer peripheral level 28 and on the other hand by distal outer peripheral level 29.

(41) In principle, catheter tube 10 may be produced in one part or in one piece. This may take place on the one hand by an appropriate extrusion method. On the other hand, catheter tube 10 may be produced with a uniform, relatively larger wall thickness of outer wall 20. In a subsequent processing step, the wall thickness, starting from the outer periphery, may be reduced sufficiently by a mechanical or laser-assisted ablation process in distal catheter portion 16 that distal catheter portion 16 ultimately has smaller outside dimensions than proximal catheter portion 15.

(42) For the example of a catheter tube 10, which is formed in one part, FIG. 5 shows a cross section through proximal catheter portion 15, wherein it can be seen that proximal catheter portion 15 has relatively large wall thickness. In contrast, FIG. 12 shows a cross section through the same catheter tube 10 in distal catheter portion 16. It is clearly visible that outer wall 20 of catheter tube 10 in distal catheter portion 16 has a smaller wall thickness than in proximal catheter portion 15. The dimensions of lumens 11, 12, 13 are preferably identical. In other words, catheter tube 10 on the whole has a constant inside diameter. Only the outside diameter of catheter tube 11 varies and is accompanied by a corresponding variation of the wall thickness of outer wall 20.

(43) Because of the reduced wall thickness of outer wall 20 in distal catheter portion 16, distal catheter portion 16 is more flexible in bending than proximal catheter portion 15. This makes it possible to advance catheter tube 10 into small and narrowly tortuous blood vessels. Improved advancability into small and narrowly tortuous blood vessels, especially good bending flexibility of catheter tube 10, is also obtained in the preferred configuration, in which distal catheter portion 16 is a scaled version of proximal catheter portion 15, i.e. when the cross-sectional areas of temperature-regulating lumens 12, 13 in distal catheter portion 16 are also smaller than in proximal catheter portion 15.

(44) The increased wall thickness of outer wall 20 in proximal catheter portion 15 stiffens proximal catheter portion 15, and so catheter tube 11 can on the whole be readily pushed along the longitudinal axis. Consequently, an advancing force applied at the proximal axial end is transferred effectively to catheter tip 18. At the same time, the increased wall thickness of outer wall 20 in proximal catheter portion 15 provides an improved insulating effect, and so temperature losses are prevented during flow through temperature-regulating lumens 12, 13 in proximal catheter portion 15. This increases the efficiency of the local temperature regulation or cooling at heat-exchanger element 14. In the catheter variant in which catheter tube 10 is produced in one piece, for example via an extrusion process, materials such as polyurethane, Pebax, nylon, thermoplastic plastics, especially thermoplastic elastomers are preferably used. In this respect, PTFE or other fluoro polymers are advantageous, since in this way the friction against a sheath and/or the vessel wall is reduced. However, it is difficult to line these materials with heat-exchanger element 14 or balloon. In that respect, nylon or PET are expedient as the material for the balloon.

(45) Instead of a one-part structure of catheter tube 10, this may also be of multi-part structure. In particular, catheter tube 10 may comprise an inner tube 23, which extends completely through proximal catheter portion 15 and distal catheter portion 16. Inner tube 23 may have constant cross section, especially in the form of the cross section according to FIG. 12. In order to increase the outside diameter in proximal catheter portion 15 and thus to create a diameter difference between proximal catheter portion 15 and distal catheter portion 16, inner tube 23 may be provided with an additional layer in proximal catheter portion 15. Specifically, it may be provided that catheter tube 10 or outer wall 20 is of multi-layer structure in proximal catheter portion 15, in which case at least one inner layer 21 and one outer layer 23 are provided.

(46) Inner layer 21 is preferably formed by inner tube 23. Outer layer 22 may be formed by a shrink-fitted tube, a full-surface covering, especially a coating, or by a further tube, which is joined to inner tube 23 by lamination, for example. In any case, full-surface, preferably material-bonded contact exists between inner layer 21 and outer layer 22. Outer layer 22 and inner layer 21 may be formed from different materials.

(47) Inner layer 21 and outer layer 22 may be produced simultaneously by a coextrusion process. Alternatively, inner tube 23 or inner layer 21 may be produced first and then outer layer 22 applied onto inner layer 21 in proximal catheter portion 15. Outer layer 22 may contain fillers, reinforcing substances or other additives, in order to impart properties other than those of inner layer 21 to outer layer 22. In particular, outer layer 22 may form a reinforcing layer, in order to increase the longitudinal axial stability of outer wall 20 in proximal catheter portion 15. For example, outer layer 22 may contain nano-reinforced composite materials, which comprise, for example, nylon, thermoplastic elastomers or thermoplastic polyurethanes. Furthermore, reinforcement of proximal catheter portion 15 may be achieved by using for outer layer 22 a material that is harder than the material of inner layer 21. Outer layer 22 may also comprise a wire mesh (braid) or a spirally wound wire (coil) as reinforcing element.

(48) For improved thermal insulation, it is preferable for outer layer 22 to be of a material with low thermal conductivity. In particular, it may be provided that the outer layer has a thermal conductivity of at most 0.2 Wm.sup.1K.sup.1, especially at most 0.15 Wm.sup.1K.sup.1, especially at most 0.1 Wm.sup.1K.sup.1, especially at most 0.08 Wm.sup.1K.sup.1.

(49) In general, outer layer 22 may be formed as an additional tube, especially as outer tube 24. Outer tube 24 may have an inside diameter larger than an outside diameter of inner tube 23. Preferably outer tube 24 is pushed over inner tube 23 in the region of proximal catheter portion 15 and joined to inner tube 23 at least at one distal axial end. For example, the distal axial end of outer tube 24 may be shrink-fitted or crimped in order to create a fluid-tight joint with inner tube 23. Outer tube 24 may also be joined to inner tube 23 by adhesive bonding or heat-sealing.

(50) The crimped axial end may form a spacer 25, which holds open a gap or insulating space 26 between outer tube 24 and inner tube 23. Other types of spacers 25 are possible. In particular, several spacers 25 may be disposed along outer tube 24, in such a way that they are joined in one piece to outer tube 24 or inner tube 23 or are disposed separately, for example as rings, between outer tube 24 and inner tube 23. Independently of the type and geometry of spacers 25, it is provided that insulating space 26 amounts to a radial height, i.e. outer tube 24 and inner tube 23 are spaced apart from one another by at least 50 m, especially at least 100 m, especially at least 150 m.

(51) FIG. 7 shows an exemplary embodiment in which catheter tube 10 in proximal catheter portion 15 is provided with radially inwardly projecting spacers 25, so that an insulating space 26 is formed between outer tube 24 and inner tube 23. Preferably several spacers 25 extend over the periphery of inner tube 23. Spacers 25 may be formed on the one hand as radially inwardly projecting elements of outer tube 24 and on the other hand as radially outwardly projecting elements of inner tube 23. Insulating space 26 preferably forms an air space, which contributes to improved insulation of outer wall 20 in proximal catheter portion 15. In general, spacers 25 may be disposed between inner tube 23 and outer tube 24 at least in the region of temperature-regulating lumens 12, 13. In the exemplary embodiment according to FIG. 7, spacers 25 are disposed over the entire periphery of inner tube 23, so that outer tube 24 and inner tube 23 are spaced apart coaxially relative to one another, in order to form insulating space 26.

(52) Insulating space 26 may also be formed without the use of spacers 25. FIG. 8 shows such an exemplary embodiment. Specifically, a cross section through a proximal catheter portion 15 of a catheter tube 10 is shown in FIG. 8, wherein outer wall 20 of catheter tube 10 in proximal catheter portion 15 is formed by an inner tube 23 and an outer tube 24. Outer tube 24 and inner tube 23 are disposed coaxially with one another and are radially spaced apart from one another. In this way an annular insulating space 26 is formed between outer tube 24 and inner tube 23.

(53) A longitudinal section through catheter tube 10 according to FIG. 8 is shown in FIG. 9. Catheter tube 10 comprises a proximal catheter portion 15 and a distal catheter portion 16. Inner tube 23 extends over the entire length of catheter tube 10, especially through proximal catheter portion 15 and distal catheter portion 16. Outer tube 24 extends exclusively along proximal catheter portion 15. Outer tube 24 forms a proximal outer peripheral level 28, which radially outwardly bounds a receiving space 17 disposed in distal catheter portion 16. Receiving space 17 is bounded radially inwardly by a distal outer peripheral level 29, which is defined by inner tube 23. Outer tube 24 is disposed coaxially relative to inner tube 23, wherein a distance exists between outer tube 24 and inner tube 23. The distance between outer tube 24 and inner tube 23 is filled by an insulating space 26. In order to close off insulating space 26, a proximal closure flange 30 is provided at the proximal end of catheter tube 10. A distal closure flange 31 is provided at the distal end of proximal catheter portion 15. Closure flanges 30, 31 are of substantially annular structure and close off insulating space 26 fluid-tightly in distal and proximal direction. For this purpose, closure flanges 30, 31 join inner tube 23 to outer tube 24.

(54) A further exemplary embodiment of the inventive medical catheter is shown in FIG. 10. In particular, a cross section through catheter tube 10 in proximal catheter portion 15 is illustrated. Within proximal catheter portion 15, catheter tube 10 has an inner tube 23 and an outer tube 24, wherein outer tube 24 is disposed eccentrically relative to inner tube 23. In particular, outer tube 24 bears on inner tube 23 in the region of through-lumen 11 or of the instrument lumen. Preferably outer tube 24 is firmly joined to inner tube 23 at this place, for example by heat-sealing or adhesive bonding. In contrast, in the region of temperature-regulating lumens 12, 13, outer tube 24 is spaced apart from inner tube 23. In this way an insulating space 26 between outer tube 24 and inner tube 23 is formed at least in the region of temperature-regulating lumens 12, 13.

(55) In order to ensure that a distance, especially an insulating space 26, exists between outer tube 24 and inner tube 23, spacers 25 may be disposed between outer tube 24 and inner tube 23, at least in the region of temperature-regulating lumens 12, 13. Such an exemplary embodiment, in which outer tube 24 is disposed eccentrically relative to inner tube 23 and in the region of temperature-regulating lumens 12, 13 is held at a distance from inner tube 23 by spacers 25, is shown in FIG. 11. By analogy with the exemplary embodiment according to FIG. 7, spacers 25 may be joined to or formed in one piece with outer tube 24 and also in one piece with inner tube 23. In any case, an insulating space 26 exists between inner tube 23 and outer tube 24 in the region of temperature-regulating lumens 12, 13. For this purpose it is not necessary to provide several spacers 25. To the contrary, a single spacer 25 may be sufficient to create a durable distance between outer tube 24 and inner tube 23. Preferably single spacer 25 is disposed (radially) opposite a joint between outer tube 24 and inner tube 23.

(56) FIG. 12 shows a cross section through catheter tube 10 in distal catheter portion 16. Within distal catheter portion 16, catheter tube 10 also has a through-lumen 11 and two temperature-regulating lumens 12, 13, which are separated from one another by an inner wall 19. Catheter tube 10 further comprises an outer wall 20, which has a relatively thin wall thickness. In particular, outer wall 20 is of single-layer structure in distal catheter portion 16. Outer wall 20 forms a distal outer peripheral level 29 of catheter tube 10.

(57) For all exemplary embodiments according to FIGS. 5 to 11, which respectively show proximal catheter portion 15, it is appropriate for the corresponding or associated distal catheter portion 16 to have a geometry according to FIG. 12. In other words, FIG. 12 shows a distal catheter portion 16 of catheter tube 10 according to one of FIGS. 5 to 11. For this purpose, distal catheter portion 16 according to FIG. 12 may be formed in one piece with proximal catheter portion 15 according to FIG. 5. Alternatively, one of the exemplary embodiments according to FIGS. 6 to 11 may be formed with an inner tube 12 that has a cross-sectional geometry according to FIG. 12 and extends beyond proximal catheter portion 15 in order to form distal catheter portion 16.

(58) In general, it is possible to provide that, in the exemplary embodiments according to FIGS. 6 to 11, outer layer 22 or outer tube 24 may be configured in such a way that the thermal conductivity is reduced. For example, outer layer 22 or outer tube 24 may have a porosity, especially a foam-like structure. This may be achieved, for example, by incorporation of microbubbles during the extrusion process. Alternatively, hollow microspheres may be incorporated in the material of outer tube 24 or of outer layer 22. On the whole, it is preferable for outer tube 24 or outer layer 22 to have cavities in which air may be received. In this way the insulating effect of outer layer 22 or of outer tube 24 is improved. Alternatively, elastomers, insulating foam layers of cross-linkable copolymers may be used for the insulation. Preferably such materials are integrated into outer layer 22 or outer tube 24. The elastomeric, insulating foam layers may contain, for example, polyethylene and polypropylene units or polyethylene-propylene diene.

(59) An alternative exemplary embodiment of the inventive catheter is shown in FIG. 13. In contrast to the foregoing exemplary embodiments, the wall thickness in the exemplary embodiment according to FIG. 13 is not varied along catheter tube 10, but instead the inside cross-sectional diameter of catheter tube 10 is reduced in distal catheter portion 16 compared with proximal catheter portion 15. Specifically, temperature-regulating lumens 12, 13 in distal catheter portion 16 have a smaller cross-sectional area than in proximal catheter portion 15. In contrast, the wall thickness of outer wall 20 may be constant along entire catheter tube 10. Likewise the cross-sectional area of through-lumen 11 is preferably constant along entire catheter tube 10. Nevertheless, it is also possible for both the wall thickness and the cross-sectional areas of the individual lumens 11, 12, 13 to vary along catheter tube 10. Temperature-regulating lumens 12, 13 may have a larger cross-sectional area in proximal catheter portion 15 than in distal catheter portion 16. Thus the volume of temperature-regulating fluid that can be passed through the temperature-regulating circuit may be increased. This optimizes the heat-exchanger function of the entire catheter. In order to improve the advancability of the catheter or catheter tube 10, it is provided that a conical transition portion 32 is formed between proximal catheter portion 15 and distal catheter portion 16. The length of conical transition portion 32 is preferably at most 120 mm, especially at most 100 mm, especially at most 80 mm, especially at most 60 mm, especially at most 40 mm, especially at most 30 mm, especially at most 20 mm. At a minimum, the length of conical transition portion 32 is preferably 10 mm.

(60) A further alternative exemplary embodiment of an inventive catheter is shown in FIGS. 14 and 15. Catheter tube according to FIGS. 14 and 15 has a proximal catheter portion 15 and a distal catheter portion 16. Proximal catheter portion 15 has a larger outside diameter than distal catheter portion 16. Within distal catheter portion 16, catheter tube 10 supports a heat-exchanger element 14. In the present case, heat-exchanger element 14 is formed as a compliant balloon. In other words, the balloon is elastic, and so it dilates radially under fluid pressure.

(61) According to FIGS. 14 and 15, the temperature-regulating circuit can be seen in the longitudinal section through catheter tube 10. The temperature-regulating circuit comprises first temperature-regulating lumen 12, a distal fluid opening 32 in outer wall 20, heat-exchanger element 14 or the compliant balloon, a proximal fluid opening 34 in outer wall 20 and second temperature-regulating lumen 13.

(62) The balloon or heat-exchanger element 14 is joined fluid-tightly to outer wall 20, so that temperature-regulating fluid can flow from distally to proximally through the balloon, i.e. from distal fluid opening 33 to proximal fluid opening 34. A catheter tip 18, which seals temperature-regulating lumens 12, 13 fluid-tightly, is mounted at the distal axial end of catheter tube 10. Catheter tip 18 has a through hole 27, which is joined to through-lumen 11, so that an instrument, for example a guide wire, may be guided through catheter tube 10 to the point of treatment.

(63) The compliant balloon or heat-exchanger element in rest condition forms a cylindrical tube which, as illustrated in FIG. 14, is disposed within receiving space 17 between proximal outer peripheral level 28 and distal outer peripheral level 29. In the exemplary embodiment according to FIGS. 14 and 15, receiving space 17 is bounded in longitudinal axial direction by transition portion 32 on the one hand and by catheter tip 18 on the other hand. Catheter tip 18 preferably has an outside diameter that corresponds to the outside diameter of proximal catheter portion 15. In this way, the balloon or heat-exchanger element 14, while catheter tube 10 is being advanced through a sheath or through a blood vessel, does not come into contact with either a sheath wall or a vessel wall. Thus no friction develops between a sheath wall or a vessel wall and heat-exchanger element 14, thus facilitating the advancing of catheter tube 10 on the whole. Specifically, it is possible to dispense with a friction-inhibiting or friction-reducing coating of the balloon or heat-exchanger element 14, which otherwise may impair heat transfer via heat-exchanger element 14. In this way heat-exchanger element 14 exhibits improved heat-transfer behavior.

(64) FIG. 15 shows the exemplary embodiment according to FIG. 14, wherein the balloon or heat-exchanger element 14 has assumed the expanded condition. The expanded condition is achieved by the fluid pressure when temperature-regulating fluid, especially a cooling medium, flows through temperature-regulating lumens 12, 13 and heat-exchanger element 14. The fluid pressure causes dilation of the compliant balloon, thus increasing the heat-transfer area. This further increases the efficiency of the inventive catheter as a heat exchanger or for hypothermic treatment.

(65) The inventive catheter may be used in particular for local blood cooling of cerebral blood vessels. Such therapeutic hypothermia may be used in particular for treatment of a stroke. Preferably the catheter is combined with a recanalization element, for example a thrombus trap. During the hypothermic treatment, the recanalization element may be guided through through-lumen 11 to a thrombus, and may then capture and remove the thrombus.

(66) Within the sense of improved bending flexibility with simultaneously high heat-exchange effect and good advancability of the catheter, the invention proposes in general to make the cross-sectional diameter of catheter tube 10 smaller in distal catheter portion 16 than in proximal catheter portion 15. Thereby proximal catheter portion 15 is reinforced, leading to improved pushability during advancing of the catheter. An increased wall thickness in proximal catheter portion 15 also improves the insulating effect of outer wall 20. A smaller wall thickness in distal catheter portion 16 leads to higher flexibility. In general, catheter tube 10 may be subdivided into further sub-regions, wherein catheter geometry, wall thickness, material properties and/or the porosity of outer layer 22 or of outer tube 24 may vary. As regards the dimensions of the catheter, the following values are generally applicable:

(67) For an outside diameter of proximal catheter portion 15 larger than 2 mm, the length of catheter tube 10 is preferably at least 80 cm, especially at least 90 cm, especially at least 100 cm, especially at least 110 cm, especially at least 120 cm. The length of catheter tube 10 is preferably at most 140 cm for an outside diameter of proximal catheter portion 15 larger than 2 mm.

(68) For an outside diameter of proximal catheter portion 16 smaller than 2 mm, the length of catheter tube 10 is preferably at least 80 cm, especially at least 90 cm, especially at least 100 cm, especially at least 110 cm, especially at least 120 cm, especially at least 130 cm, especially at least 140 cm. The length of catheter tube 10 for an outside diameter of proximal catheter portion 15 smaller than 2 mm is preferably at most 160 cm.

(69) The wall thickness of outer tube 24 is preferably between 100 m and 300 m, preferably between 150 m and 250 m. If outer wall 20 in proximal catheter portion 15 is provided with an outer layer 22, this preferably has a layer thickness between 50 m and 150 m, especially between 70 m and 130 m, especially between 90 m and 100 m.

(70) On the whole, it is appropriate for preferred exemplary embodiments of the invention, especially in the case of a catheter tube formed in one piece, for the difference of the outside diameter between the proximal catheter portion and the distal catheter portion to be between 100 m and 1000 m, especially between 200 m and 800 m, especially between 300 m and 700 m, especially between 400 m and 600 m, preferably especially 500 m. In this connection the respective three-lumen sub-region (containing three lumens) is being considered (not the tip, if this consists of a single lumen).

(71) For good pushability of catheter tube 10, flexible distal catheter portion 16 is preferably limited in length. In particular, distal catheter portion 16 may have a length that amounts to at most 120 mm, especially at most 100 mm, especially at most 80 mm, especially at most 60 mm. Preferably, however, distal catheter portion is longer than 20 mm.

(72) An exemplary embodiment of the invention has the following technical specifications: Catheter tube 10 is suitable for advancing through a sheath of 8 French size (inside diameter of the sheath approximately 2.8 mm); The outside diameter of proximal catheter portion 15 is between 2.3 mm and 2.7 mm, preferably between 2.5 mm and 2.7 mm, especially specifically 2.6 mm; The outside diameter of distal catheter portion 16 is between (without heat-exchanger element/balloon) 1.9 mm and 2.3 mm, preferably between 2.0 mm and 2.2 mm, especially specifically 2.1 mm; The overall length of catheter tube 10 is between 1.0 m and 1.2 m, preferably 1.1 m; The length of distal catheter portion 16 is between 40 mm and 120 mm, especially between 60 mm and 100 mm, preferably between 70 mm and 90 mm, especially specifically 80 mm.

(73) FIG. 16a shows one longitudinal and two cross sections of an inventive catheter according to a preferred exemplary embodiment. Catheter tube 10 comprises a proximal catheter portion 15 and a distal catheter portion 16, wherein distal catheter portion 16 has a smaller outside diameter than proximal catheter portion 15. The exemplary embodiment according to FIG. 16a corresponds substantially to the exemplary embodiment according to FIG. 13. However, in catheter tube 10 according to FIG. 16a, distal catheter portion 16 is a scaled version of proximal catheter portion 15. In other words, the cross sections of the two catheter portions 15, 16 are similar to one another in the mathematical or geometric sense. In particular, the ratio between the cross-sectional areas of temperature-regulating lumens 12, 13 and inner wall 19 is identical in proximal catheter portion 15 and in distal catheter portion 16. This is clearly visible in FIG. 16b and FIG. 16c.

(74) A longitudinal section through a distal catheter portion 16 of a catheter tube 10 is shown in FIG. 17a. The longitudinal section does not cut through the longitudinal axis of catheter tube 10, but instead is laterally offset (FIG. 17b). Through-lumen 11 is clearly visible. In the illustrated exemplary embodiment, a dilator 35 extends through it. Through-lumen 11 has a constant, invariable cross-sectional diameter. In contrast, the outside diameter of catheter tube 10 is variable. In particular, catheter tube 10 has a catheter tip 18, which directly adjoins distal catheter portion 16. Heat-exchanger elements 14 are disposed in distal catheter portion 16, but for reasons of clarity are not illustrated here. Thus distal catheter portion 16 is defined as that portion close to catheter tip 18 which supports the balloon or the balloons.

(75) Besides eccentrically or laterally disposed through-lumen 11, two temperature-regulating lumens 12, 13 extend in catheter tube 10. Temperature-regulating lumens 12, 13 end upstream from a taper 36, which forms the transition from distal catheter portion 16 to catheter tip 18. The taper narrows toward catheter tip 18 and forms substantially a frustoconical outer contour.

(76) FIG. 17c shows a cross section through catheter tube 10 in distal catheter portion 16. Temperature-regulating lumens 12, 13 resembling pulmonary lobes as well as off-centered through-lumen 11, which has a circular cross section, are clearly visible. The cross-sectional geometry of catheter tube 10 in the region of taper 36 is shown in FIG. 17d. Therein the outer wall 20 of catheter tube 10 has an irregular wall thickness. It is also possible for temperature-regulating lumens 12, 13 to continue into taper 36 and also to narrow (gradually), i.e. temperature-regulating lumens 12, 13 may have a distally decreasing cross-sectional diameter in the region of taper 36. In this respect, temperature-regulating lumens 12, 13 may be visible in certain cross-sectional views of taper 36. Preferably the wall thickness in the region of the prolongation of temperature-regulating lumens 12, 13 disposed in proximal catheter portion 15 is larger than on a diametrically opposite side of through-lumen 11.

(77) FIG. 17e shows a cross section through dilator 35 disposed inside through-lumen 11, especially in the region of a dilator tip 35a. The dilator is provided with a guide lumen 35b, which has a constant cross-sectional diameter substantially over the entire length of dilator 35. The dilator is able to be guided over a guide wire through guide lumen 35b to the point of treatment.

(78) Further sections through the catheter or catheter tube 10 according to FIG. 17a are shown in FIGS. 18a, 18b, 19a, and 19b, wherein a proximal catheter portion 15 is also illustrated. It can be seen that catheter tube 10 has a transition portion 32, which is disposed between proximal catheter portion 15 and distal catheter portion 16. Catheter tip 18 adjoins distal catheter portion 16 via taper 36. Temperature-regulating lumens 12, 13 of catheter tube 10 extend via transition portion 32 into distal catheter portion 16, which supports heat-exchanger elements 14 (not illustrated here). The wall thickness of inner wall 19 and of outer wall 20 may be constant in transition portion 32. Preferably, however, the wall thickness varies in direct proportion to the change of the outside diameter or to the change of the cross-sectional diameter of temperature-regulating lumens 12, 13.

(79) Catheter tip 18 may in general comprise a material that is softer or more flexible than the material of proximal and/or distal catheter portion 15, 16. In this way it is ensured that catheter tip 18 can be guided easily into the desired target vessel in the region of vessel branches, especially bifurcations. Moreover, good contact with a dilator 36 is ensured in this way, which achieves advantages especially for the sheath variant. Finally, catheter tip 18 has advantages for aspiration of thrombi, since the distal opening of through-lumen 11 is located more distally by virtue of catheter tip 18. In this respect it has proved expedient when catheter tip 18 has a length of at least 0.5 cm, especially at least 1 cm, especially at least 2 cm, especially at least 3 cm, especially at least 4 cm, especially at least 5 cm. At most, catheter tip 18 should have a length of 8 cm. In general, it is also provided that catheter tip 18 contains only one single lumen, especially through-lumen 11. Preferably catheter tip 18 has a distally tapering outer contour.

(80) In this connection, it is pointed out that the diagrams according to FIGS. 17a to 19a, 19b may relate both to the sheath variant and to the catheter variant of the catheter. In the sheath variant, the catheter, especially catheter tube 10, may itself assume the function of a sheath, so that an additional sheath for puncturing a blood vessel and for guiding the catheter is not necessary. In the catheter variant, catheter tube 10 is guided to the point of treatment via a sheath introduced beforehand into the blood vessel.

(81) As regards the geometry of catheter tube 10 at its proximal end, the use of a Luer-Lock adapter is provided. The Luer-Lock adapter is preferably joined firmly to catheter tube 10 and it permits access, especially for guide wires and/or fluids, to the various lumens of catheter tube 10. In particular, the Luer-Lock adapter is designed in such a way that, via this, an access to temperature-regulating lumens 12, 13 as well as to through-lumen 11 is possible.

(82) As regards the dimensions of a catheter tube of an inventive catheter (catheter variant), which can be advanced in particular via a sheath of 8 French size, the following characteristic values are preferred:

(83) TABLE-US-00001 Proximal Distal catheter portion catheter portion Outside diameter [mm] 2.3-2.8 1.9-2.3 advantageously: advantageously: 2.5-2.7 2.0-2.2 preferably: preferably: Total length [m] 0.9-1.3 advantageously: 1.0-1.2 preferably: 1.1 Length of the distal catheter 40-160 portion or balloon region advantageously: [mm] 60-140 advantageously: 80-120 advantageously: 90-110 preferably: 100 Length of the transition at least 10 region [mm] and at most 120 or at most 100 or at most 80 or at most 60 or at most 40 or at most 30 or at most 20 Wall thickness [m] 100-300 50-250 advantageously: 150-250 advantageously: preferably: 200 100-200 preferably: 150 Ratio of outside diameter of 0.6-0.95 distal catheter portion/ advantageously: 0.7-0.9 outside diameter preferably: 0.8 of proximal catheter portion Difference between outside 200-1000 diameter of distal catheter advantageously: 300-800 portion and advantageously: 400-600 outside diameter preferably: 500 of proximal catheter portion

(84) As regards the dimensions of a catheter tube 10 of an inventive catheter (sheath variant), which in the context of a double function acts both as a sheath for an 8 French catheter and also as a catheter, the following characteristic values are preferred:

(85) TABLE-US-00002 Proximal Distal sheath portion sheath portion Outside diameter [mm] 3.2-4.0 2.3-3.6 advantageously: 3.4-3.9 advantageously: 2.6-3.4 advantageously: 3.5-3.8 advantageously: 2.8-3.3 preferably: 3.6-3.7 advantageously: 2.9-3.2 preferably: 3.0-3.1 Inside diameter of the through-lumen [mm] 5F variant 1.7-2.1 Preferably: 1.8-2.0 6F variant 2.1-2.4 Preferably: 2.2-2.3 Total length [m] 0.8-1.0 preferably: 0.9 Length [mm] 40-120 advantageously: 60-100 advantageously: 70-90 preferably: 80 Length of the transition region at least 10 [mm] and at most 120 or at most 100 or at most 80 or at most 60 or at most 40 or at most 30 or at most 20 Wall thickness [m] 100-400 50-300 advantageously: 200-300 advantageously: 150-250 preferably: 250 preferably: 200 Ratio of outside diameter of distal 0.6-0.95 catheter portion/outside advantageously: 0.7-0.9 diameter of proximal preferably: 0.8 catheter portion Difference between outside 100-1000 diameter of distal catheter advantageously: 200-1000 portion and advantageously: 300-800 outside diameter of proximal advantageously: 400-600 catheter portion preferably: 500

(86) As follows from the tables, within the scope of the present invention we distinguish between a sheath and a catheter when referring to size values. For a catheter, the size value in French relates to the outside diameter of the catheter tube. In contrast, a sheath with the same size value has a larger outside diameter, since the size value of a sheath relates instead to the maximum size of a catheter than can be advanced through the sheath. Thus the outside diameter of an 8 French sheath corresponds instead to the outside diameter of an 8 French catheter plus the wall thickness of the sheath.

(87) In principle, a size of 8 French is preferred for the catheter tube in the present invention, wherein this size value relates, in the case of the catheter variant, to the outside diameter and, in the case of the sheath variant, to the inside diameter of the through-lumen (plus a tolerance, so that an 8 French catheter is able to be pushed through through-lumen 11). Nevertheless, other sizes are also possible. Catheter tube 10 may also be scaled, so that sizes of 4, 6, 5 or 7 French up to 9, 10, 11 or 12 French are attained. In such cases the dimensions of the individual lumens as well as inner and outer walls of catheter tube 10 are preferably at least approximately proportional to one another.

LIST OF REFERENCE SYMBOLS

(88) 10 Catheter tube 11 Through-lumen 12 First temperature-regulating lumen 13 Second temperature-regulating lumen 14 Heat-exchanger element 15 Proximal catheter portion 16 Distal catheter portion 17 Receiving space 18 Catheter tip 19 Inner wall 20 Outer wall 21 Inner layer 22 Outer layer 23 Inner tube 24 Outer tube 25 Spacer 26 Insulating space 27 Through opening 28 Proximal outer peripheral level 29 Distal outer peripheral level 30 Proximal closure flange 31 Distal closure flange 32 Transition portion 33 Distal fluid opening 34 Proximal fluid opening 35 Dilator 35a Dilator tip 35b Guide lumen 36 Taper