CRYOPROBE

Abstract

A cryoprobe having a head to which cryofluid is supplied via a capillary tube. A hose serves for removal of the cryofluid, wherein the capillary tube extends through the lumen thereof. The capillary tube comprises a flexible section that is bridged by a pull element. In this manner a cryoprobe that can be handled well is obtained that can be easily and very largely bent and still transmits tensile forces for sample extraction.

Claims

1. A cryoprobe configured for tissue sampling in the upper urinary track of a patient, the cryoprobe comprising: a hose that comprises a lumen and that is provided with a head at its distal end; a fluid channel that is arranged at its distal end in a manner communicating with the head; and at least one pull element that is assigned to the hose and is arranged in a manner extending over at least a portion of the length of the hose.

2. The cryoprobe according to claim 1, wherein the fluid channel is formed by a capillary tube that extends through the lumen and that is arranged for transmitting tensile forces in the lumen, and wherein the capillary tube consists of a material, the tensile strength of which can be increased or decreased by a treatment.

3. The cryoprobe according to claim 1, wherein the capillary tube comprises at least one section in which the tensile strength and/or the flexibility of the material is reduced compared with the tensile strength of the remaining capillary tube.

4. The cryoprobe according to claim 3, wherein the capillary tube consists of steel and that the section is softened.

5. The cryoprobe according to claim 2, wherein the pull element is arranged spanning at least one section of the capillary tube, preferably without pretension.

6. The cryoprobe according to claim 2, wherein the pull element comprises two ends, at least one of which is connected with the capillary tube.

7. The cryoprobe according to claim 6, wherein both ends of the pull element are connected, preferably welded, to the capillary tube such that the pull element spans the section.

8. The cryoprobe according to claim 7, wherein the ends of the pull element are connected with the capillary tube, preferably via weld seams, external of section.

9. The cryoprobe according to claim 8, wherein the weld seams are longitudinally orientated on the capillary tube.

10. The cryoprobe according to claim 8, wherein the weld seams are arranged in the same angular position with reference to the capillary cross-section.

11. The cryoprobe according to claim 1, wherein the pull element is formed by one or multiple wires of high strength steel, particularly stainless steel having a tensile strength >900 N/mm.sup.2.

12. The cryoprobe according to claim 1, wherein the pull element is largely arranged parallel to the capillary tube.

13. The cryoprobe according to claim 1, wherein only one pull element is arranged in the lumen.

14. The cryoprobe according to claim 1, wherein the diameter of the pull element is smaller than the difference between the diameter of the lumen and the outer diameter of the capillary tube.

15. The cryoprobe according to claim 1, wherein the hose is configured having two lumen, the two lumen of which are the lumen and the fluid channel, and wherein the pull element extends through the lumen or the fluid channel or through the wall of the hose.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Further details of advantageous embodiments of the invention yield from the drawings, the description and the claims. The drawings show:

[0019] FIG. 1 an endoscope with an embodiment of an inventive probe in schematic perspective illustration,

[0020] FIG. 2 the distal end of the endoscope with probe in bent condition,

[0021] FIG. 3 the distal end of the probe in a schematic longitudinal sectional illustration,

[0022] FIG. 4 a portion of the distal end of the probe in a schematic longitudinal sectional illustration,

[0023] FIGS. 5 and 6 sectional illustrations of the probe according to FIG. 4 cut along the lines V-V or VI-VI respectively,

[0024] FIG. 7 an alternative embodiment of the instrument,

[0025] FIG. 8 the instrument according to FIG. 7 in cross-section.

DETAILED DESCRIPTION

[0026] FIG. 1 illustrates an endoscope 10 in which a cryoprobe 11 is inserted. It extends from the proximal end 12 of the endoscope up to the distal end 14 that is movable by means of operating elements 13. The endoscope 10 comprises a longitudinal shaft 15, wherein the cryoprobe 11 is guided through a channel thereof. The distal end 16 of the cryoprobe 11 can be retracted into the shaft 15 or shifted out of the shaft 15. The outer diameter of the cryoprobe 11 is preferably slightly smaller than the inner diameter of the channel provided in the shaft 15.

[0027] The operating elements 13 serve to control the distal end 14 of the shaft 15, particularly to selectively bend it relative to the axial direction 17 that, as shown in FIG. 2, extends along the shaft 15. The angle that can be achieved thereby is preferably larger than 90 and further preferably larger than 140 and in the preferred case larger than 160. The bending radius is thereby smaller than 20 mm, preferably smaller than 15 mm in case of an outer diameter of the shaft 15 of less than 3.3 mm.

[0028] In FIG. 3 the cryoprobe 11 is individually illustrated in the area of its distal end 16. It comprises a hose 18 at the distal end 19 of which a head 20 is attached in fluid tight manner. The hose 18 surrounds a lumen 21 and is at least highly flexibly configured at least in the section adjoining the head 20. The head 20 is schematically illustrated in FIG. 3. It preferably comprises an outer diameter that corresponds to the outer diameter of the hose 18. At its distal end the head 20 is closed by a planar, curved or otherwise configured bottom.

[0029] In addition, the hose is provided with a fluid channel 22 that serves to guide cooling fluid to or in the head 20. The fluid channel 22 can be formed by a capillary tube 22a that extends through the lumen 21 of the hose 18. The capillary tube 22a can be connected with head 20 at its head-side end 23. The connection can be established by not further illustrated connection elements or, as obvious from FIG. 3, directly by a weld seam 24, a weld point or the like.

[0030] The capillary tube 22a can be open at its distal end or can be provided with a nozzle. The nozzle can also be formed on the capillary tube. Preferably the capillary tube 22a consists of a tensile-force-proof steel, e.g. X2CrNiMo 1.4404 or X2CrNiMo 1.4401. Preferably the material of the capillary tube 22a has a tensile strength of more than 900 N/mm.sup.2. The capillary tube 22a serves to insert cryofluid in the inner space of the head 20 for cooling thereof, as well as for transmission of tensile forces during the biopsy sampling.

[0031] The capillary tube 22a is, however, not continuously configured in a tensile-force-proof manner. In its section 25, that is individually illustrated in FIG. 4, the capillary tube 22a is reduced in its tensile strength and thus also in its bending resistance by a heat treatment, e.g. by softening. Preferably the tensile strength in this section is less than 700 N/mm.sup.2. In doing so, the capillary tube 22a is also in the section 25 able to resist a pressure load caused by the cryofluid. It is in addition flexible such that the cryoprobe can be bent with a small bending radius, as indicated in FIG. 2. However, section 25 has not enough tensile strength, in order to transmit the necessary tensile forces for biopsy sampling.

[0032] The section 25 is bridged by a pull element 26 that is a pull wire 27 in the present embodiment. It consists of a tensile-force-proof material that transmits the tensile forces necessary for the biopsy sampling within its elastic stress in connection with the capillary tube 22a. The pull wire 27 is connected at its two ends by weld connections 28, 29, e.g. weld seams, with the capillary tube 22a that also transmits the tensile forces within its elastic stress. The pull element 26, however, keeps tensile stresses to a large extent away from the softened location of the capillary tube 22a. Measured along the length of the capillary tube 22a the distance of the weld seams 28, 29 from each other is, however, larger than the length of the section that is reduced in its tensile strength and bending resistance compared with the remaining capillary tube 22a.

[0033] This is illustrated in FIGS. 5 and 6, which also make apparent that the weld connections 28, 29 at the two ends of the pull wire 27 are arranged at the same radial position of the capillary tube 22a. Between the two weld connections 28, 29 the pull wire 27 is in non-tensioned (slack) and transversely movable contact with the capillary tube 22a or extends with low distance thereto, as indicated in FIG. 3. In this orientation the pull wire 27 is largely orientated parallel to the capillary tube 22a.

[0034] For biopsy sampling the cryoprobe 11 is inserted into a lumen of the patient with the endoscope 10 and the distal end 16 is brought into contact with the tissue of the patient to be sampled or is penetrated therein. The insertion of the cryoprobe 11 in the endoscope 10 is particularly simplified in that the cryoprobe 11 is rigidcorresponding to the rigidity of the capillary tube 22anearly along its total length, i.e. more rigid than section 25. The instrument is, however, flexible as a whole. Only the portion of the length defined by section 25 is less bending resistant and easier to bend.

[0035] The endoscope can be bent in an angle of over 160 if necessary, as illustrated in FIG. 2. In doing so, the endoscope 10 and the cryoprobe 11 can be inserted into narrow and highly branched vessels of a patient. Thereby the cryoprobe 11 is dimensioned such that the section 25 is located in the region of the bending location of the endoscope. The length of section 25 is thereby preferably so long that the bending is possible, if the head 20 is still positioned at the opening of the distal end 14 of the shaft 15 as well as if the head 20, as shown in FIGS. 1 and 2, is shifted out of the shaft 15. Preferably the length of section 25 has an amount of more than some centimeters, preferably more than 10 cm. The bending of endoscope 10 is only slightly hindered by the stiffness of the capillary tube 22a, because section 25 is configured in a corresponding flexible manner. The hose 18 is also made of a flexible material, preferably plastic, preferably PEEK or PA, that only slightly hinders the bending of the endoscope. The tensile-force-proof pull wire 27 also opposes no remarkable resistance to the bending due to its small diameter. The diameter of the pull element 26, particularly the pull wire 27, is less than the diameter of the capillary tube 22a.

[0036] For sampling the head 20 is applied with cryofluid at the inside that is inserted into the head 20 via the capillary tube 22a. Due to the cooling of head 20, portions of the tissue to be sampled freeze to the head 20.

[0037] For sampling the cryoprobe 11 is moved in proximal direction. In doing so, the tissue frozen to the head 20 is torn off the remaining tissue. The force required for this is first transmitted via the capillary tube 22a up to the weld connection 29 and therefrom via the pull wire 27 to the weld connection 28. From there the flux of force is via the capillary tube 22a to the head 20. The pull wire 27 thus bridges the non-tensile-force-proof section 25 with regard to force transmission.

[0038] It is further possible to connect the pull element 26 only at the connection location 28 with the capillary tube 22a and to guide it through the total length of the cryoprobe 11 up to its proximal end. In this case the capillary tube 22a can be configured from the proximal end up to the connection location 28 completely or in one or more sections of a metallic or non-metallic material that is more flexible than the remaining capillary tube 22a.

[0039] It is further possible to connect the distal end of the pull element 26 directly with the head 20, whereas the proximal end of the pull element is connected via the weld connection 29 or another connection with the capillary tube 22a. In this case, the capillary tube 22a can be configured originating from the weld connection 29 or another connection location up to its distal end completely or partly of a material that is more flexible and less tensile-force-proof than the remaining capillary tube 22a.

[0040] It is further possible that the capillary tube 22a is completely or in one or more sections formed from a flexible, non-bending resistant and non-tensile-torque-proof material. In this case the pull element 26 is attached with its distal end to the head 20 or an element connected therewith, whereas its proximal end is connected with the proximal end of the cryoprobe 11.

[0041] It is indicated that instead of a pull wire 27 also a tensile-force-proof metallic band, wire bundle, a rope, a tube or the like can be used as pull element 26. Also instead of a metallic pull element 26 a non-metallic pull element can be used, the ends of which are also connected with the capillary tube 22a in order to bridge at least the section 25 or longer sections of the capillary tube 22a or the whole capillary tube 22a. The pull element 26 can also be configured as mono-filament or as rope from a non-metallic material or from a composite material, e.g. a fiber composite material.

[0042] In a preferred embodiment the capillary tube is only flexible in its section 25. The section 25 has typically a length of 10 cm to 30 cm and is limited to a length obtained by the sum of the length of the actively bendable section of the endoscope and the maximum extension length of the cryoprobe 11 out of the endoscope 10 during use. The length of the pull element 26 is dimensioned such that at least the whole length of the flexible section 25 of the capillary tube 22a is bridged. In doing so, the pull element 26 is fixed proximally in a force transmission manner to the capillary tube 22a and distally to the head 20 or to the capillary tube 22a, if the flexible section does not extend up to this location. Because the capillary tube 22a is only soft in section 25 and apart therefrom rigid, the cryoprobe 11 can be handled in the usual manner. It is also ensured that the pull element 26 limits the cross-section of the lumen 21 only along a short length of the hose 18 and thus does not remarkably increase the flow resistance therein.

[0043] FIG. 7 illustrates a modified embodiment of the instrument 11 for which the description above applies accordingly on the basis on the introduced reference numerals. However, the instrument 11 according to FIG. 7 is modified compared with instrument 11 according to FIGS. 3 to 6. Its hose 18 is configured with two lumen, in that the fluid channel 22 is arranged parallel to the lumen 21. FIG. 8 illustrates in an enlarged cross-section an exemplary channel arrangement. While the fluid channel 22 can comprise, for example, a circular cross-section, the cross-section of lumen 21 can be configured in a manner deviating from the circular shape, as illustrated in FIG. 8 or can also be circular.

[0044] In the embodiment of instrument 11 according to FIGS. 7 and 8, again a pull element 26 is assigned to the hose 28, e.g. in form of a pull wire 27 that can extend, for example, through the lumen 21 and that can be connected with its distal end to the head 20 at a weld seam 24. The pull wire 27 can extend up to the proximal end of the hose 18 in order to transmit tensile forces from there to the head 20.

[0045] Further tensile-force-proof elements can be considered as pull elements 26, as e.g. ribbons, profile wires, wire bundles, ropes or the like. The material of the pull element 26 can be a metal or also a non-metal, as e.g. carbon fibers, aramid fibers or the like. As an alternative the pull element 26 can be embedded in the wall of hose 18. However, preferably the pull element 26 is in all embodiments, according to FIGS. 3 to 8, arranged in longitudinal direction of the instrument 11, whereby the pull element 26 is preferably arranged in a straight orientation. Preferably the pull element encircles neither the lumen 21 nor the fluid channel 22, but is arranged substantially parallel thereto.

[0046] An embodiment of an inventive cryoprobe comprises a head 20, to which cryofluid is supplied via a capillary tube 22a. A hose 18 serves for removal of the cryofluid, wherein the capillary tube 22a extends through the lumen 21 thereof. The capillary tube 22a comprises a flexible section 25 that is bridged by a pull element 26. In this manner a cryoprobe 11, that can be handled well, is obtained that can be easily and very largely bent and still transmits the necessary tensile forces for sample extraction.