CRYOSURGERY INSTRUMENT

Description

[0001] The invention relates to a cryosurgical instrument that operates by utilizing the Joule-Thomson effect.

[0002] Medical instruments are known from the prior art whose working end is cooled to produce physiological or therapeutic effects on the patient's tissue. For example, WO 02 / 02026 A1 discloses a cryoprobe having a cutting tip, with liquid coolant being directed to the tip to cool it. US Pat. No. 6,830,581 B2 describes a heat transfer element for insertion into a blood vessel, which is intended to cool blood in the vessel by supplying cooled working fluid to the tip of the instrument.

[0003] Instruments for cryosurgery, for example, work by deliberately using the Joule-Thomson effect, whereby a fluid experiences a reduction in its temperature by throttling it.

[0004] For example, DE 10 2008 024 946 A1 discloses a cryosurgical instrument that has a supply line for supplying a fluid, in particular a gas, into an expansion chamber in the probe head. A diaphragm with an opening is arranged on the end face of the supply line, through which the fluid flows from the supply line into the expansion chamber and is expanded, thereby cooling the fluid. This cools the probe tip. The cooled fluid flows back from the probe tip through a gas return line.

[0005] WO 2006 / 006986 A2 describes a cryosurgical instrument with a closed-end tube. A gas supply line is arranged within the tube, at the end of which a capillary tube is connected, the end of which opens into an expansion chamber in the tip of the probe.

[0006] US 2012 / 0 130 359 A1 describes a cryotherapy instrument that can be used to influence nerves at the site of application with cold for therapeutic purposes. The instrument has a shaft, at the end of which is a working section. A supply line for supplying coolant extends through the shaft into the working section. A throttle orifice plate or a capillary tube can be arranged at the end of the supply line, through which the supply line opens into an expansion chamber in the working area.

[0007] US 2005 / 0016 188 A1 describes an instrument for cryosurgical removal of tissue using a cryocatheter with a tube whose distal end is closed, wherein a supply line extends in the tube to the end of the instrument, wherein a capillary tube is arranged in the end of the supply line, which opens into a chamber at the distal end of the instrument.

[0008] US Pat. No. 5,759,182 discloses a cryosurgical instrument having a heat exchanger in its handle 10 for exchanging heat between an internal high-pressure line and an external return line. The internal high-pressure line has two funnel-shaped constrictions at two locations, namely in front of and behind the heat exchanger. From there, the high-pressure gas supply line extends within the shaft to the cryotip, where it has an outlet opening. DE 699 06 320 T discloses a cryosurgical instrument having an internal supply line that gradually tapers from a proximal end to a distal end. In the opposite direction, the return line also gradually widens from the distal end to the proximal end.

[0009] WO 99 / 66970 A discloses a blood cooling instrument in which an internal capillary line extends to a distal end of the instrument and opens into a return line at an outlet opening. The capillary line is open at its end to allow a coolant to flow out. The return line has sections of different diameters, with funnel-shaped sections arranged between the sections of different diameters.

[0010] US 2003 / 0310822 A1 discloses a cryosurgical instrument with a cooled electrode. For cooling, the electrode sits on a tubular body, inside which is a coolant supply line. This line tapers at its end in a funnel shape toward an outlet opening.

[0011] It is an object of the present invention to provide an improved cryosurgical instrument.

[0012] This object is achieved with a cryosurgical instrument according to claim 1, which can be configured, for example, to obtain a tissue sample. The cryosurgical instrument according to the invention has a supply line for supplying a working fluid, in particular a gas, into an expansion chamber, which is preferably arranged at the distal end of the instrument. The supply line has a capillary line section that opens into the expansion chamber. A return device for returning gas from the expansion chamber is connected to the expansion chamber. The supply line has at least a first section and a second section, which form line sections with different sized internal cross-sections (internal cross-sectional areas). The internal cross-sections determine the flow cross-section for the fluid through the supply line in the first and second sections.The supply line of the instrument according to the invention is designed such that the flow path of the fluid through the supply line tapers in a funnel-shaped manner in the direction of the expansion chamber in a transition section of the supply line from the first section to the second section. This funnel-shaped taper of the internal cross-section of the supply line in the transition section can create a stepped course of the flow cross-section along the supply line with a preferably continuous (steady) or step-by-step decrease in the internal cross-section in the taper region. Because the internal cross-section of the supply line tapers at least once in a funnel shape in the flow direction of the fluid through the supply line towards the expansion chamber, the fluid is accelerated in the at least one funnel-shaped transition section of the supply line.Due to the funnel-shaped taper in the transition section, the flow cross-section does not decrease abruptly from the flow cross-section of the first section to the flow cross-section of the second section, which is smaller than the flow cross-section of the first section. Thus, due to the funnel shape of the transition section, pressure fluctuations of the accelerated fluid in the section of the supply line following the funnel-shaped transition section can be largely reduced or avoided.

[0013] The instrument according to the invention uses the Joule-Thomson effect to cool the working section of the instrument, which is evident in the fluid during expansion in the expansion chamber. The uniform acceleration in the transition section and the use of the capillary line section as the distal end section of the supply line result in the distance over which the fluid particles largely remain together after exiting the outlet opening into the expansion chamber being longer than with an instrument that does not have the described funnel-shaped taper and a capillary line section. This prevents, in particular, the jet from expanding excessively directly after the outlet, thus impeding the return flow of the gas from the expansion chamber.This allows the instrument head, which contains the expansion chamber and may contain at least a section of the return device, to be designed to be slim. This paves the way for miniaturized instrument heads. The use of the capillary line as a throttle for the fluid and the largely pressure surge-free acceleration of the fluid in the at least one transition section, where the flow cross-section tapers in a funnel shape, pave the way, in particular, for a particularly slim instrument head, which can simplify, for example, safe tissue sampling.

[0014] Particularly preferably, the supply line is designed such that the internal cross-section of the supply line tapers in a funnel shape in the transition section to the capillary line section. This accelerates the fluid, and pressure fluctuations upon entry into the capillary line section can be largely reduced or avoided, resulting in a long free path for the fluid, over which the fluid particles largely remain together after exiting the capillary line section into the expansion chamber. Preferably, the taper of the internal cross-section is continuous in a transition region extending from before the transition section to the capillary line section, through the transition section, and into the capillary line section.The inner wall surface of the supply line in the transition region is preferably edge-free, so that within the transition region along the flow path there are no sudden changes in the gradient of the inner cross-section.

[0015] Preferably, the taper angle at which the inner cross-section of the supply line tapers in a funnel-like manner, at least in the transition section to the capillary line section, is between a minimum of 15° and a maximum of 40°. The taper angle is enclosed by opposite sections of the inner wall surface of the transition section, which determines the flow cross-section through the transition section.

[0016] The length of the capillary line section is preferably between a minimum of 1 mm and a maximum of 15 mm. The inner diameter of the capillary line section, which determines the flow cross-section of the capillary line section, is preferably between a minimum of 60 micrometers and a maximum of 200 micrometers.

[0017] Preferably, the supply line has at least two transition sections in which the flow path through the supply line tapers in a funnel shape in the flow direction to the expansion chamber.

[0018] The first section and the second section preferably form step sections of a series of two, three, or more than three step sections of the supply line, wherein a transition section is arranged between each two step sections, to which the two step sections adjoin. As described, the flow cross-section decreases through at least one transition section, preferably in each of the transition sections, like a funnel, in the direction of the outlet opening of the supply line to the expansion chamber. The surface areas of the internal cross-sectional areas of each step section belong to an internal cross-sectional step, wherein the surface areas of the internal cross-sectional areas of an internal cross-sectional step of a step section are larger than the surface areas of the internal cross-sectional areas of the internal cross-sectional step of the step section adjoining the same transition section downstream in the direction of the outlet of the capillary line section.This creates a stepped course of the flow cross-section of the supply line up to the mouth of the supply line, wherein the flow path in the transition sections with funnel-shaped taper does not taper abruptly from one cross-sectional step to the following cross-sectional step due to the funnel shape, but preferably tapers largely continuously or stepwise, or continuously in at least one longitudinal section of the transition section and stepwise in at least one other longitudinal section of the transition section, in the direction of the expansion chamber, and can preferably remain largely constant in the step sections along the step sections. The capillary line section can form the last step section of the series in the flow direction toward the mouth.Due to the acceleration in the funnel-shaped transition sections, the fluid particles reach a high velocity, which carries the fluid jet deep into the expansion chamber after exiting the orifice. This increases the fluid's expansion area and thus improves the cooling efficiency. Due to the funnel-shaped taper and the arranged stepped sections, the fluid accelerates gradually toward the expansion chamber along the row, reducing pressure surges and turbulence in the fluid. This increases the area in the expansion chamber where the gas expands.

[0019] The flow cross-section for the fluid preferably increases abruptly as it transitions from the outlet of the capillary line section into the expansion chamber. This promotes a strong development of the Joule-Thompson effect on the expanding fluid. Furthermore, a section of the expansion chamber can be used as part of the recirculation device.

[0020] The supply line is preferably arranged in the return line and / or the return line is arranged, for example, adjacent to the supply line. Particularly preferably, the ratio of the flow cross-section in the return line adjacent to the capillary line section and / or around the capillary line section to the internal cross-section of the capillary line section is greater than or equal to 5.

[0021] Preferably, the supply line is designed such that the external cross-section (external cross-sectional area) of the supply line at the funnel-shaped transition sections does not decrease abruptly from the external cross-section of a step section to the external cross-section of the step section adjacent to the same transition section, but preferably decreases continuously or stepwise, or stepwise in at least one subsection of the section of the supply line whose external cross-section tapers, and continuously in at least one other subsection of the section in the direction of the mouth of the capillary line section. Viewed in the flow direction of the gas flowing away from the expansion chamber after expansion, the external cross-section of the supply line at the funnel-shaped transition sections accordingly does not increase abruptly, but preferably continuously and / or stepwise.If the wall of the supply line simultaneously forms a wall of the return device, in particular a return line, the return of the gas from the expansion region can be improved by the space provided by the reduction in the external cross-section. Unlike a sudden decrease in the external cross-section of the supply line toward the orifice, the flow cross-section for the returning gas is not abruptly changed, for example, tapered, during a continuous or stepwise decrease in the external cross-section. This can reduce the flow resistance of the return device, in particular a return line.

[0022] The instrument can be designed such that the flow cross-section of the return line in the flow direction of the gas during the return away from the expansion chamber decreases continuously or stepwise at the transition sections or continuously in at least one longitudinal section at the transition sections and stepwise in at least one other longitudinal section.

[0023] Preferably, at least the section of the supply line is formed as a seamless, one-piece assembly with the capillary line section and the transition section adjacent to the capillary line section. This simplifies the process-reliable manufacture of the instrument by avoiding disruptions and abrupt changes in the flow cross-section of the supply line toward its opening. Particularly preferably, at least the section of the supply line is formed as a seamless, one-piece assembly with the capillary line section and the funnel-shaped transition sections, thus simplifying the process-reliable manufacture of the transition sections and the capillary line section.

[0024] The supply line as a whole can be manufactured using a rotary swaging process. Preferably, at least the section of the supply line with the capillary line section and the transition section adjacent to the capillary line section is manufactured using the rotary swaging process. Particularly preferably, at least the section of the supply line with the capillary line section and the funnel-shaped transition sections is manufactured using the rotary swaging process. The rotary swaging process reliably achieves high quality with low surface roughness and low surface waviness on the inner surface of the supply line, which determines the flow cross-section.

[0025] The wall thickness of the capillary line section can be equal to or less than the wall thickness of the supply line section adjacent to the transition section to the capillary line section upstream. This facilitates the provision of a large space adjacent to or around the capillary line section for the recirculation of gas from the expansion zone. Furthermore, it can increase the heat transfer between the gas recirculated adjacent to or around the capillary line section and the gas supplied through the capillary line section.

[0026] According to the invention, the ratio of the inner diameter of the capillary line section to the length of the capillary line section is between a minimum of 0.004 and a maximum of 0.2.

[0027] Preferably, the outlet opening of the capillary line section, through which the fluid exits the supply line and enters the expansion chamber, is arranged on the end face of the capillary line section. Preferably, the casing of the capillary line section, which encloses the lumen of the capillary line section through which the fluid flows, is free of lateral openings.

[0028] The distance between the orifice and the opposite wall surface of the expansion chamber, which defines the lumen of the expansion chamber, is preferably between a minimum of 0.5 mm and a maximum of 5 mm .

[0029] Further advantageous features of the cryosurgical instrument according to the invention emerge from the subclaims as well as the following description and the figures.

[0030] They show: Figure 1- a distal end of a state-of-the-art cryosurgical instrument in a partial longitudinal section, Figure 2a - a partial view of an exemplary cryosurgical instrument according to the invention in a longitudinal section, Figures 2b to 2d - Cross-sectional views of the Figure 2a the instrument according to the invention shown in Figure 2a registered cutting planes, Figure 3 - a section of an exemplary cryosurgical instrument according to the invention in a longitudinal section, Figure 4 - a section of a cryosurgical instrument according to the invention according to a further exemplary embodiment in a longitudinal section, Figure 5 - a partial longitudinal sectional view of an exemplary cryosurgical instrument according to the invention guided in the working channel of an endoscope, Figure 6- a partial longitudinal sectional view of an exemplary instrument according to the invention and Figure 7 - a partial longitudinal sectional view of an exemplary instrument according to the invention.

[0031] Figure 1shows a distal end section 13 of a prior art cryosurgical instrument 10 in a longitudinal section. The instrument 10 has a shaft 11 that extends to a head 12 of the instrument 10 at the distal end 13a of the instrument 10. An adhesion surface 14 is provided on the outside of the head 12, to which a tissue sample can be frozen for removal. A supply line 15 for supplying gas to the distal end 13a of the instrument 10 is arranged within the shaft 11. The supply line 15 ends with a throttle diaphragm 16 having an opening (orifice) 17 through which the gas can flow from the supply line 15 into an expansion chamber 18 in the head 12 of the instrument 10.When the gas flow from the supply line 15 is throttled at the orifice plate 16, and the gas expands after the orifice plate 16 upon entering the expansion chamber 18, the Joule-Thomson effect is exhibited in that the gas expanding in the expansion chamber 18 experiences a reduction in temperature. This allows it to cool the head 12 of the instrument 10 with the adhesion surface 14. The cooled gas leaves the expansion chamber 18 through a return line 19, which is arranged in the shaft 11 next to the supply line 15. The backflow of the gas from the expansion chamber 18 into the return line 19 can be determined, as indicated by the arrows in . Figure 1 As indicated, the gas flowing out of the outlet opening 17 may be obstructed. Therefore, a relatively large expansion chamber 18 must be provided to ensure adequate backflow.

[0032] Figure 2ashows a cryosurgical instrument 10 according to the invention in a longitudinal section. In the cryosurgical instrument 10 according to the invention, the distal end 20 of the supply line 15 is formed by a capillary line section 21 (capillary tube section). The capillary line section 21 has an opening 22 into the expansion chamber 18 on the end face 23 of the capillary line section 21. The capillary line section 21 extends into the head 12 of the instrument 10, which is formed by a cap 24 that defines the expansion chamber 18. The distance 25 between the opening 22 of the capillary line section 21 and the opposite wall surface 26 of the cap 24, which defines the expansion chamber 18, is preferably a minimum of 0.5 mm to a maximum of 5 mm.The wall surface 26 of the cap 24 opposite the mouth 22 of the capillary tube section 21 and defining the lumen 27 of the expansion chamber 18 can, as shown, be, for example, a spherical cap surface 26 which is designed and arranged to guide the gas impinging on the wall surface 26 of the cap 24 into the return line 19.

[0033] The capillary line section 21 forms the n-th step section 30n of a series of at least n=2, preferably n>2, for example, and as in Figure 2ashown, n=3 step sections 30n-2, 30n-1, 30n of the supply line 15. Between each step section 30n-2, 30n-1, 30n, a transition section 32n-2, 32n-1 is arranged, to which the two step sections 30n-2, 30n-1 and 30n-1, 30n are adjacent. In at least one transition section 32n-2, 32n-1, the inner cross-sectional area 33 of the supply line 15 decreases in the distal direction 34 towards the mouth 22 of the capillary line section 21, preferably in a funnel shape, for example conically, so that when the instrument 10 is subjected to a fluid, e.g. .a gas in the transition sections 32n-2, 32n-1 leads to an acceleration of the fluid flowing through the supply line 15 to the orifice 22. The inner wall surface 35 of the transition section 32n-1 adjacent to the capillary tube section 21 preferably has essentially no surface sections positioned perpendicular to the flow direction 34 of the gas, against which the gas flowing through the transition section in the flow direction 34 to the expansion chamber 18 would have to flow. The same preferably also applies to each of the remaining transition sections 32n-1. Rather, the exemplary transition section 32n-1 shown on the capillary tube section 21 has an inner wall surface 35 which, viewed in the longitudinal section through the transition section 32n-1, is inclined to the flow direction 34, the circumferential sections of which enclose acute angles of less than 90° with the flow direction 34. The remaining transition sections 32n-2 are preferably designed in the same way. Fig. 2ashows a funnel-shaped transition section 32n-2 to the penultimate stage section 30n-1 and a funnel-shaped transition section 32n-1 to the capillary line section 30n, which forms the last stage section 30n of the series. Preferably, the flow path tapers continuously in a transition region 36 from before the transition section 32n-1 to the capillary line section 30n, 21, through the transition section 32n-1, into the capillary line section 21. Preferably, in the transition region 36 in the flow path in the supply line 15, there are essentially no inner wall surfaces of the supply line 15 positioned perpendicular to the flow direction 34, which would lead to a sudden change in the flow cross-section.Preferably, the flow cross-section of the supply line 15 in each transition section 32n-2, 32n-1 of the supply line 15 between the step sections 30n-2, 30n-1, 30n decreases in a funnel shape in the flow direction 34 in the direction of the mouth 22, so that preferably a row of alternately arranged step sections 30n-2, 30n-1, 30n and transition sections 32n-2, 32n-1 with a funnel-shaped inner cross-sectional taper is formed.

[0034] It is advantageous if the flow cross-section in the transition section(s) 32n-2, 32n-1 of the supply line 15 does not decrease abruptly from the flow cross-section in the step section 30n-2 or 30n-1 of the supply line 15, which is arranged upstream of the transition section 32n-2 or 32n-1 and borders the transition section 32n-2 or 32n-1, to the flow cross-section in the step section 30n-1 or 30n of the supply line 15, which in the flow direction 34 borders the transition section 32n-2 or 32n-1 after the transition section 32n-2 or 32n-1, but if the flow path in the transition section(s) 32n-2, 32n-1 each extends over a section of the flow path tapered towards the orifice 22. This reduces fluid turbulence and pressure fluctuations in the step section 30n-1, 30n of the supply line 15 following the transition section 32n-2 or 32n-1.

[0035] The taper angle 37 of the inner cross-section 33 in the transition section 32n-1 to the capillary tube section 21, 30n is preferably a minimum of 15° to a maximum of 40°. The taper angle 37 is determined by the inner wall surface 35 of the transition section 32n-1, which laterally delimits the flow cross-section through the transition section 32n-1. The inner wall surface 35 of the transition sections 32n-2, 32n-1 is preferably arranged at an angle to the flow direction 34, as viewed in the longitudinal section through the supply line 15 along the flow direction 34. The inner wall surface 35 can, for example, be a truncated cone surface or a truncated pyramid surface. The transition section 32n-2 to the penultimate stage section 30n-1 and / or the transition section 32n-1 to the capillary line section 21 can be symmetrical with respect to a plane parallel to the flow direction 34.The centers of the flow cross-sectional areas in the transition section 32n-2 to the penultimate stage section 30n-1 and / or the centers of the flow cross-sectional areas in the transition section 32n-1 to the capillary line section 21 can, as in a symmetrical funnel, lie on a straight line perpendicular to the flow cross-sectional area at the inlet to the respective transition section 32n-1, 32n-2. As an alternative to a symmetrical funnel-shaped taper of the flow cross-section in one or more transition sections 32n-2, 32n-1, the flow cross-section of the transition section 32n-2 to the penultimate stage section 30n-1 and / or of the transition section 32n-1 to the last stage section 30n can taper, for example, as in an asymmetrical funnel.

[0036] The step sections 30n-2, 30n-1, 30n define internal cross-section steps. In a step section 30n-2, 30n-1, 30n, the internal cross-sections belong to an internal cross-section step. Within each step section 30n-2, 30n-1, 30n, the internal cross-section of the supply line 15 remains within a specific value range (step). Within a step section 30n-1, 30n, the flow cross-section can, for example, be constant. The internal cross-sections in the value range of a step section 30n-2, 30n-1 are larger than the internal cross-sections in the value range of the respective downstream (toward the outlet) step section 30n. The supply line 15 accordingly has a stepped course of the internal cross-section with a non-jumpy, but preferably continuous or step-by-step transition of the flow cross-section to the next stage between the stages in the transition sections 32n-2, 32n-1.It is also possible for the flow cross-section in at least one transition section 32n-2, 32n-1 to taper stepwise in at least one first longitudinal section of the transition section 32n-2, 32n-1 and continuously in at least one other longitudinal section of the transition section 32n-2, 32n-1, which is arranged upstream or downstream of the first longitudinal section, so that the flow cross-section in the transition section 32n-2, 32n-1 tapers continuously and stepwise to the next step. The supply line 15 can in particular be designed such that the internal cross-section of the supply line 15 decreases monotonically from the beginning of the series of step sections 30n-2, 30n-1, 30n in the flow direction 34 up to the mouth 22 of the supply line 15. This means that the internal cross-section decreases strictly monotonically, at least in sections, and may remain the same in sections.

[0037] In one embodiment, the inner wall surface 35 of the supply line 15 in the transition section 30n-1 onto the capillary line section 21 into the capillary line section 21 up to the mouth 22 of the supply line 15 can be free of edges or kinks oriented transversely to the flow direction 34 through the supply line 15, which would mean a sudden change in the gradient of the flow cross section of the supply line 15.

[0038] The flow cross-section of the return line 19 is preferably formed next to the supply line 15 and / or around the supply line 15. In the illustrated embodiment, the supply line 15 is arranged at least partially in the return line 19. The flow cross-section of the return line 19 is limited on the one hand by the wall 38a of the shaft and the wall 38b of the head 12 and on the other hand by the wall 39 of the supply line 15. The supply line 15 is in the Figure 2a as arranged coaxially in the shaft 11 and the cap 24. However, the supply line 15 as well as the shaft 11 and / or the cap 24 may instead be non-coaxial, preferably with parallel central axes.

[0039] Preferably, the outer cross-section 40 of the supply line 15 at the transition sections 32n-2, 32n-1, as shown, does not decrease abruptly in the direction 34 toward the orifice 22, but preferably continuously or stepwise. At at least one transition section 32n-2, 32n-1, the outer cross-section 40 of the supply line 15 can decrease continuously in longitudinal sections and stepwise in longitudinal sections toward the orifice 22. As a result, the flow cross-section 41 of the return line 19, as in the embodiment according to Figure 2aAs shown, at the transition sections 32n-2, 32n-1 in the direction 42 of the gas flowing away from the expansion chamber 18 through the return line 19, the flow cross-section decreases over the length of the transition sections, i.e., not abruptly from the flow cross-section before the transition section 32n-2, 32n-1 to the flow cross-section after this transition section 32n-2, 32n-1. The flow cross-section 41 of the return line 19 can decrease in the flow direction 42 of the gas flowing away from the expansion chamber 18 at the transition sections 32n-2, 32n-1, in particular continuously or stepwise or continuously and stepwise in longitudinal sections. The flow cross-section 41 of the return line 19 next to the capillary tube section 21, 30n or around the capillary tube section 21, 30n and / or between the transition sections 32n-2, 32n-1 can be largely constant.

[0040] The step sections 30n-2, 30n-1, 30n preferably define external cross-sectional steps. At a step section 30n-2, 30n-1, 30n, the external cross-sections (external cross-sectional areas) of the supply line 15 belong to an external cross-sectional step. Within each step section, the external cross-section of the supply line remains within a specific value range (step). Along a step section 30n-2, 30n-1, 30n, the external cross-sections of the step section 30n-2, 30n-1, 30n can, for example, be constant. The external cross-sections in the value range of a step section 30n-2, 30n-1 are larger than the external cross-sections in the value range of the respective downstream (towards the outlet) subsequent step section 30n-1, 30n. The supply line 15 accordingly preferably has a stepped course of the outer cross-section with a non-jumpy transition of the outer cross-section to the next stage between the stages at the transition sections 32n-2, 32n-1.Rather, the transition preferably extends over the length of the transition section 32n-2, 32n-1, and / or the transition of the outer cross-section to the next stage is preferably continuous or, from the perspective of the flowing fluid, occurs stepwise. The outer cross-section of the supply line 15 is between the sections shown in . Figure 2c illustrated transition sections 32n-2, 32n-1 and between the transition section 32n-1 to the capillary line section 21 and the mouth 22 is preferably largely constant, so that the capillary line section 21 has an outer cross-section that is largely constant over the longitudinal extent of the capillary line section 21.

[0041] As shown by the Figures 2b to 2d shown, takes place in the Figure 2aIn the exemplary embodiment shown, due to the design of the supply line 15 in the shaft 11, the ratio of the flow cross-sectional area 41 (An-2, An-1, An) of the return line 19 next to a step section 30n-2, 30n-1, 30n or around a step section 30n-2, 30n-1, 30n to the internal cross-sectional area 33 (Bn-2, Bn-1, Bn) in the step section 30 in the flow direction 34 toward the mouth 22 from step section to step section is therefore greatest at the capillary line section 21. Accordingly, An:Bn≥An-1:Bn-1≥An-2:Bn-2 applies.

[0042] The ratio of the surface area of ​​the flow cross-section of the return line 19 next to the capillary line section 21 and / or around the capillary line section 21 to the surface area of ​​the flow cross-section of the capillary line section 21 is preferably greater than or equal to 5. The inner diameter 28 (for the sake of clarity, shown as an example in Figure 3The diameter of the capillary line section (shown in the figure) determines the flow cross-section 33 of the capillary line section. The ratio of the inner diameter 28 of the capillary line section 21 to the length 29 (illustrated for clarity in Figure 3 The diameter (shown in the figure) of the capillary line section 21 is preferably between a minimum of 0.004 and a maximum of 0.2. The length 29 of the capillary tube forming the capillary line section 21 can, for example, be between a minimum of 1 mm and a maximum of 15 mm. The inner diameter 28 of the capillary line section 21 can, for example, be between a minimum of 60 micrometers and a maximum of 200 micrometers.

[0043] The section of the supply line 15 with the transition sections 32n-2, 32n-1, the step section 30n-1 between the transition sections 32n-2, 32n-1, and the capillary line section 21, 30n is preferably formed as a seamless, one-piece assembly. This section can be manufactured, for example, using the rotary swaging process. The cap 24 of the shaft 11 forming the head 12 with the adhesion surface 14 can be made of stainless steel, for example. The shaft 11 can be made of PEEK, PA, PUR, or PTFE, for example. The shaft 11 can be rigid or flexible.

[0044] During operation of the cryosurgical instrument 10, the following occurs: With the aid of a fluid source (not shown) connected to the supply line 15, the supply line 15 is supplied with fluid, in particular gas, for example N 2 O or CO 2 , wherein the fluid flows at the distal working end 43 of the cryosurgical instrument 10 from a tubular step section 30n-2, 30n-1, 30n through the adjacent transition section 32n-2, 32n-1 in the direction of the mouth 22 and expansion chamber 18 into the subsequent tubular step section 30n-2, 30n-1, 30n. Due to the funnel-like decrease in the internal cross-section 33 and thus in the flow cross-section of the supply line 15 in the transition sections 32n-2, 32n-1 in the direction of the expansion chamber 18, the fluid is accelerated in the transition sections 32n-2, 32n-1.By reducing the flow cross-section 33 from stage to stage in the transition sections 32n-2, 32n-1, which is not abrupt but extends over a certain length, preferably continuously or stepwise, turbulences and pressure fluctuations due to acceleration in each transition section 32n-2, 32n-1 are largely avoided. The step sections 30n-2, 30n-1, 30n preferably each have a length such that any turbulences and / or pressure fluctuations that still occur in the step section 30n-2, 30n-1, 30n following a transition section 32n-2, 32n-1 largely or completely subside. The gas enters the capillary tube section 21 (n-th step section) from the (n-1)th step section through the (n-1)th transition section.Any pressure fluctuations in the gas due to the transition from the (n-1)th stage section to the capillary tube section 21 preferably subside completely due to the design of the capillary tube section 21. This results in a laminar flow in the flow direction 34 to the mouth 22 with a corresponding velocity profile which, due to the subsidence of the pressure fluctuations in the capillary tube section 21 in the distal end section of the capillary tube section 21, which borders on the mouth opening 22, preferably no longer changes in the flow direction 34 (undisturbed flow profile). The capillary tube section 21 forms the throttle for the gas for the development of the Joule-Thomson effect. A throttle orifice 16, as in the prior art according to . Fig. 1, which leads to a strong expansion of the fluid jet when leaving the feed line 15 into the expansion chamber 18 and thus to a strong interaction with the returning gas, can therefore, as in Figure 2ashown, can be omitted. The gas flow flows from the capillary tube section 21 into the expansion chamber 18 and, due to the acceleration in the transition sections 32n-2, 32n-1 and the freedom from pressure fluctuations before exiting the orifice 22, far into the expansion chamber 18 in the direction of the opposite wall surface 26 of the instrument head 12. The gas flows out of the orifice 22 largely unhindered by the backflowing gas. The gas flowing out of the orifice 22 and expanding in the expansion chamber 18 experiences a temperature reduction due to the Joule-Thomson effect and cools the head 12 and the adhesion surface 14 in such a way that a tissue sample can be frozen to the adhesion surface 14. The tissue sample can then be separated from the remaining tissue by pulling on the instrument 10 and removed.

[0045] The return flow of the cooled gas is accordingly not hindered by the escaping gas. Rather, the expanded gas from the expansion chamber flows preferably parallel to the fluid leaving the supply line 21 through the orifice 22 into the expansion chamber 18, with the opposite flow direction, from the expansion chamber 18 into the return line 19. This large-scale return flow is Figure 3, which shows a section of the instrument 10 at its distal end 13a, illustrated by the arrows. The gas flowing back through the return line 19 brushes against the outer wall surface of the capillary tube section 21 of the supply line 15 and extracts heat from the gas flowing through the capillary tube section 21. This is supported by the fact that the wall 44 of the capillary tube section 21 is preferably as thin as the wall of the step section 30n-1, which borders the transition section 32n-1 on the capillary tube section 21, or even thinner.

[0046] The backflowing gas can escape, for example, through lateral openings (not shown) in the shaft 11.

[0047] Figure 4 shows a section of a modified exemplary embodiment of the instrument 10 according to the invention. An end section 13 of the instrument 10 is shown.

[0048] The supply line 15 and the return line 19 are formed adjacent to one another in the shaft 11 of the instrument 10. The capillary tube section 21 of the supply line 15 is inserted into the section of the supply line 15 arranged in the shaft 11. The capillary tube section 21 extends into the cap 24 of the instrument 10, which defines the expansion chamber 18.

[0049] The supply line 15 has at least three step sections 30n-2, 30n-1, 30n, with the last step section 30n being formed by the capillary tube section 21. At least in the transition section 32n-2 to the penultimate step section 30n-1, the internal cross-section of the supply line 15 decreases in a funnel shape toward the opening 22 into the expansion chamber 18.

[0050] The flow cross-section of the return line 19 connected to the expansion chamber 18 in the shaft 11 increases in a funnel shape in transition sections 19m-2, 19m-1 of the return line 19. Between the transition sections 19m-2, 19m-1 of the return line 19, the flow cross-section in the return line 19 is preferably largely constant. The number of transition sections 19m-2, 19m-1 of the return line 19 can correspond to the number of transition sections 32n-3, 32n-2, 32n-1 in the supply line 15.

[0051] Figure 5shows a cryosurgical instrument 10 according to the invention, the shaft 11 of which is guided for longitudinal movement in a working channel 45 of an endoscope 46. The head 12 of the instrument 10 is arranged at the distal end of the shaft 11 of the instrument 10 with a slender distal end section 47, wherein the outer diameter 48 of the end section 47 is reduced compared to the outer diameter 49 of the shaft section adjacent to the head 12. The capillary tube section 21 projects into the narrow end section 47, into the expansion chamber 18, which is delimited by the end section 47.In the exemplary embodiment, the fluid is accelerated in at least two consecutive transition sections 32n-2, 32n-1 of the supply line 15, each with a funnel-shaped taper of the internal cross-section 33, in the flow direction 34 toward the opening 22 into the expansion chamber 18. A tubular step section 30n-1, 30n adjoins each transition section 32n-2, 32n-1. The distally last step section 30n is the capillary tube section 21.Due to the uniform acceleration in the transition sections 32n-2, 32n-1 and due to the decay of pressure fluctuations in the capillary tube section 21, so that the flow profile of the fluid flowing towards the expansion chamber 18 through the supply line 15 at the end of the capillary tube section 21 is preferably constant in the flow direction 34, i.e. no longer changes in the flow direction 34, the fluid flows far into the expansion chamber 18 after exiting the mouth 22. Due to this, a suitable return of the expanded gas from the expansion chamber 18 without hindrance by the gas flowing out of the mouth 22 into the expansion chamber 18 is possible even in the space limited by the slender end section 47 of the instrument head 12. With the instrument head 12, a tissue sample 50 can now be obtained, the diameter of which is smaller than the diameter of the working channel 45 of the endoscope 46.Thus, the head 12 of the instrument 10 with the tissue sample 50 can be retracted into the working channel 45 of the endoscope 46 after the tissue sample 50 has been obtained, so that the tissue sample 50 can be safely removed from the patient's body in the working channel 45 of the endoscope 46.

[0052] Figure 6shows a section of an instrument 10 according to the invention with a head 12, which is fastened to the shaft 11 of the instrument 10 by a tubular fastening section 51. The head 12 has a pointed end section 52, and a tubular attachment section 53 is arranged between the end section 52 and the fastening section 51. The head 12 has a waist 54 on the attachment section 53. In particular, the outer diameter of the attachment section 53 is reduced compared to the outer diameter of the pointed end section 52. The wall of the attachment section 53 preferably has a reduced thickness compared to the wall of the fastening section 51. The attachment section 53 delimits the expansion chamber 18, which can extend into the pointed end section 52. The capillary line section 21 of the supply line 15 extends into the adhesion section 53. The pointed end section 52 facilitates the puncture of the tissue for sample collection.To take the sample, the supply line 15 of the instrument 10 is pressurized with fluid, whereby the fluid flows through the supply line 15 in the direction of flow to the expansion chamber 18, expands in the expansion chamber 18, and cools the head 12. The freezing effect on the tissue can emanate in particular from the adhesion section 53. Taking the sample is simplified because the reduced outer diameter of the adhesion section 53 compared to the outer diameter of the pointed end section 52 creates a positive connection between the head 12 and the frozen tissue.

[0053] Figure 7shows a section of the distal end 13 of an exemplary embodiment of the instrument 10 according to the invention with a head 12 that is attached to the shaft 11 by means of a head receiving part 55. The head receiving part 55 of the instrument 10 extends within the lumen defined by the shaft 11 and the head 12. The outer diameter of the capillary line section 21 is smaller than the outer diameter of the step section 30n-1 adjacent to the transition section 32n-1 to the capillary line section 21. Due to the example of the continuous tapering of the inner cross-section of the supply line 15 in the transition section 32n-1 to the capillary line section 21, any impairment of the backflow of the expanded gas by the fluid flowing out of the supply line 15 is largely avoided.In addition, the flow resistance of the return line 19 can be improved by the continuous increase in the outer cross-section 40 of the supply line 15 at the transition section 32n-1 (in the flow direction of the gas flowing away from the expansion chamber 18) compared to an instrument with a sudden increase. The design of the supply line 15 therefore enables suitable return of the expanded gas despite the reduction in free volume by the head receiving part 55. The wall surface 26 opposite the mouth 22 of the capillary tube section 21 and delimiting the expansion chamber 18 is, in this embodiment as well as in the embodiment according to . Figure 6 a conical surface.

[0054] A cryosurgical instrument 10 is specified, which has a supply line 15 for supplying fluid into an expansion chamber 18 of the instrument 10. The supply line 15 has a capillary line section 21 that opens into the expansion chamber 18 and forms a throttle for the fluid to develop the Joule-Thompson effect when the fluid expands in the expansion chamber 18. The flow cross-section of the supply line 15 decreases in a funnel shape in the flow direction 34 toward the expansion chamber 18 in at least one transition section 32n-2, 32n-1, preferably in two or more transition sections 32n-2, 32n-1, of the supply line 15. Each transition section 32n-2, 32n-1 is followed in the flow direction 34 by a step section 30n-1, 30n of the supply line 15, in which the flow cross-section is preferably largely constant.The last stage section 30n-1, 30n is preferably formed by the capillary line section 21. In the stage sections 30n-1, 30n, pressure fluctuations in the fluid can subside. Due to the acceleration of the fluid in the transition sections 32n-2, 32n-1 and the subsidence of pressure fluctuations in the capillary tube section 21 and, if applicable, in the further stage sections 30n-1, 30n-2, the expansion area in the expansion chamber 18 is enlarged without impeding the return flow of the expanded gas from the expansion chamber 18.

[0055] By using the capillary tube section 21 and the funnel-shaped transition section(s) 30n-2, 30n-1, the free path length of the fluid jet without expansion of the fluid jet is greatly increased in the instrument 10 according to the invention compared to a cryosurgical instrument with a throttle orifice at the end of the supply line 15, so that the interaction between the fluid flowing away from the outlet opening 22 into the expansion chamber 18 and the gas flowing back from the expansion chamber 18 can be greatly reduced. Preferably, in one embodiment of the instrument 10 according to the invention, pressure fluctuations and / or turbulences of the fluid flowing through the supply line 15 toward the outlet 22 subside in the capillary tube section 21 to such an extent that they no longer determine the free path length of the fluid jet without expansion in the expansion chamber 18.The free path length of the fluid jet without expansion is measured from the orifice 22 in the flow direction 34 of the fluid to the point in the expansion chamber 18 at which the fluid jet diameter exceeds an amount equal to the amount of the outer diameter of the capillary line section 21 at the orifice 22, or the free path length of the fluid jet without expansion is measured from the orifice 22 in the flow direction 34 of the fluid to the point in the expansion chamber 18 at the level (in the flow direction 34) at which an interaction of the fluid jet flowing away from the orifice 22 into the expansion chamber 18 with the gas flowing back to the return line 19 begins. List of reference symbols:

[0056] 10 instrument 11 shaft 12 Head 13 Distal end section of the instrument 13a Distal end of the instrument 14 Adhesion surface 15 supply line 16 throttle plate 17 opening 18 Expansion chamber 19 Return line 19m-2, 19m-1 Transition sections of the return line 20 Distal end of the supply line 21 Capillary line section / capillary tube section 22 mouth 23 front side 24 cap 25 Distance 26 Wall surface 27 lumens 28 diameter 29 length 30n-2, 30n-1, 30n Step section 32n-2, 32n-1 Transition section 33 Internal cross-sectional area / flow cross-sectional area 34 Flow direction to the expansion chamber 35 Inner wall surface 36 Transition area 37 taper angle 38a wall of the shaft 38b Wall of the head 39 Wall of the supply line 40 External cross-section 41 Flow cross-section of the return line 42 Flow direction away from the expansion chamber 43 distal working end 44 Wall of the capillary tube section 45 Working channel 46 endoscope 47 final section 48 Outer diameter end section 49 Outer diameter shaft 50 Tissue sample 51 Fastening section 52 final section 53 Attachment section 54 waist 55 Head support part An-2, An-1, An Flow cross-sectional area of ​​the return line Bn-2, Bn-1, Bn Flow cross-sectional area of ​​the supply line S 1 -S 1 , S 2 -S 2 , S 3 -S 3 Cutting planes

Claims

1. A cryosurgical instrument (10) having a feed line (15) for supplying fluid, in particular gas, into an expansion chamber (18), wherein the supply line (15) comprises a capillary line section (21) which opens into the expansion chamber (18), having a return device (19) connected to the expansion chamber (18) for returning gas from the expansion chamber (18), wherein the feed line (15) has at least a first section (30n-2, 30n-1) and a second section (30n-1, 30n) with different sized inside cross-sections (33), wherein the flow path through the feed line (15) tapers in a funnel-shaped manner in a transition section (32n-2, 32n-1) from the first section (30n-2, 30n-1) to the second section (30n-1, 30n) in the flow direction (34) of the fluid toward the expansion chamber (18), wherein the ratio of the inner diameter (28) of the capillary line section (21) to the length (29) of the capillary line section (21) is between a minimum of 0.004 and a maximum of 0.2.

2. The cryosurgical instrument (10) according to claim 1, wherein the flow path in the feed line (15) tapers in a funnel-shaped manner in the transition section (32n-1) to the capillary line section (21, 30n).

3. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the feed line (15) has at least two transition sections (32n-2, 32n-1), in which the flow path of the feed line (15) tapers in a funnel-shaped manner in the flow direction (34).

4. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the first section (30n-2, 30n-1, 30n) and the second section (30n-2, 30n-1, 30n) are step sections (30n-2, 30n-1, 30n) of a series of two or more than two step sections (30n-2, 30n-1, 30n) of the feed line (15), wherein between two step sections (30n-2, 30n-1, 30n) there is arranged a transition section (32n-2, 32n-1) in each case, said transition section being adjacent to the two step sections (30n-2, 30n-1, 30n), wherein the inside cross-sections (33) of each step section (30n-2, 30n-1, 30n) belong to an inside cross-section step, wherein the inside cross-sections of an inside cross-section step of a step section (30n-2, 30n-1, 30n) are larger than the inside cross-sections of the inside cross-section step of the step section (30n-2, 30n-1, 30n) adjacent to the same transition section (32n-2, 32n-1) in the direction (34) toward the mouth (22) of the capillary line section (21) in the flow direction.

5. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the instrument (10) is configured in such a manner that the flow cross-section (33) for the fluid increases abruptly during the transition from the mouth (22) of the capillary line section (21) into the expansion chamber (18).

6. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein feed line (15) is arranged in a return line (19) of the return device (19) and / or wherein the return line (19) is arranged next to the return line (15), wherein the ratio of the flow cross-section (41) of the return line (19) next to the capillary line section (21) or around the capillary line section (21) to the inside cross-section (33) of the capillary line section (21) is greater than or equal to 5.

7. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the outside cross-section (40) of the feed line (15) decreases continuously in the funnel-shaped transition sections (32n-2, 32n-1) in the direction (34) toward the mouth (22) of the capillary line section (21).

8. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the feed line (15) having the capillary line section (21) and the transition sections (32n-2, 32n-1) is seamlessly formed in one piece.

9. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the section of the feed line (15) having the capillary line section (21) and the funnel-shaped transition sections (32n-2, 32n-1) is produced by a rotary swaging process.

10. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the wall thickness of the capillary line section (21) is equal to or less than the wall thickness of the feed line section adjacent to the transition section (32n-2, 32n-1) toward the capillary line section (21).

11. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the tapering angle (37) at which the inside cross-section (33) tapers in a funnel-like manner in the transition section (32n-2, 32n-1) is between a minimum of 15° and a maximum of 40°.

12. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the mouth opening (22) of the capillary line section (21) is arranged on the front side (23) of the capillary line section (21).

13. The cryosurgical instrument (10) according to at least one of the preceding claims, wherein the distance (25) between the mouth opening (22) and the opposite wall surface (26) of the expansion chamber (18) is between a minimum of 0.5 millimeters and a maximum of 5 millimeters.