Cryoprobe with reinforcing element

Abstract

Aspects of the present invention provide a miniaturized cryoprobe having a shaft diameter of up to 2 mm and including a reinforcing element that can act as a handle for manipulating the cryoprobe. Aspects of the present invention generally relate to devices, systems, and methods that can include a cryoprobe. In some cases, the cryoprobe can include an elongated shaft and an operating head having an expansion chamber. The elongated shaft can include a first passage configured to provide high-pressure gas to the expansion chamber; a second passage for exhausting gas from the expansion chamber; and a vacuum chamber coaxially arranged around the first passage and the second passage.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Provisional Application No. 62 / 823,366 filed on March 25, 2019 and Provisional Application No. 62 / 754,352 filed on November 1, 2018, all of which are incorporated herein by reference in their entirety. Background Art

[0003] The present invention relates to a cryoprobe used in cryoablation and a system used for cryoablation.

[0004] During cryosurgery, surgeons can deploy one or more cryoprobes to ablate a target area of ​​a patient's anatomical structure by freezing and thawing tissue. In one example, the cryoprobe uses the Joule-Thomson effect to produce cooling or heating of the probe tip. In this case, the expansion of the cryofluid in the cryoprobe from a higher pressure to a lower pressure results in cooling the device tip to a temperature at or below those temperatures necessary to cryoablate tissue near the tip. Heat transfer between the expanded cryofluid and the outer wall of the cryoprobe results in the formation of an "ice ball" in the tissue surrounding the tip and subsequent cryoablation of the tissue.

[0005] The cryoprobe may take the form of a percutaneously deployed needle. Conventional cryoablation techniques incorporate the use of multiple cryoneedles, each of which may be individually controlled to cryoablate a pre-planned three-dimensional ablation volume. The use of an array of such cryoprobes allows control of the shape of the ablation volume and allows accurate three-dimensional placement of an ice ball formed in a manner that conforms to the size, form, and location of the tissue to be ablated. However, a disadvantage of this technique is that, due to the introduction of multiple cryoprobes, the cryoprobes may become difficult to control and handle as the operating area becomes more crowded. Commercially available cryoprobes are provided with straight or curved shafts to facilitate placement.

[0006] The cryonephedrine shaft is typically about 150 to 250 mm in length. Due to the length of the shaft, the rotational torque on the shaft in situ is relatively large, which affects the ease of positioning and the lateral force on the tip within the tissue. This is particularly significant when ablating tissue within a few centimeters of the surface.

[0007] Furthermore, currently available devices are configured to produce relatively large ice balls and are therefore less useful in situations where small ablations are required or where more rigorous contouring is desired, such as around delicate tissue. Summary of the invention

[0008] Therefore, in a first aspect, the present invention provides a cryoprobe for use in cryoablation, comprising: a slender shaft having a distal end and a proximal end; an operating head at the distal end of the slender shaft, wherein the operating head includes an expansion chamber; the slender shaft includes a first passage, the first passage is used to provide high-pressure gas to the expansion chamber and wherein the first passage terminates in a Joule-Thomson orifice at its distal end, a second passage, the second passage is used to exhaust gas from the expansion chamber, wherein the second passage is coaxially arranged around the first passage, and a vacuum chamber, the vacuum chamber is coaxially arranged around the first passage and the second passage; the cryoprobe additionally includes a slender reinforcing element positioned toward the distal end of the slender shaft and in fixed engagement therewith, the reinforcing element being configured to reduce deflection of the slender shaft over the length of the reinforcing element during use.

[0009] A cryoprobe is a cryoneveld, for example, for percutaneous use.

[0010] The elongated shaft has a distal end and a proximal end and includes a first passageway, a second passageway and a vacuum chamber. The diameter of the shaft is defined by the outer diameter of the vacuum chamber.

[0011] An operating head is disposed at the distal end of the elongated shaft.

[0012] The cross-section of the elongated shaft has a diameter of 0.9 to 2.0 mm at its widest point. Preferably, the elongated shaft has a diameter of 0.9 to 1.4 mm, especially 1.0 to 1.3 mm, most preferably the elongated shaft has a diameter of 1.2 mm + / - 0.1 mm.

[0013] The combined shaft and operating head extends distally beyond the reinforcing element (measured from the tip of the operating head to the distal-most extent of the reinforcing element at a location adjacent to the shaft) to a length of up to 100 mm, preferably 8 to 60 mm, more preferably 20 to 40 mm, and most preferably 30 mm + / - 5 mm.

[0014] The axial proximal portion extends beyond the reinforcing member as a "tail" and terminates proximally at a junction configured to connect at least the first passage to a source of cryogenic fluid, such as a source of cryogenic gas. The junction may also be configured to receive an outlet pipe and provide an opening to allow the returned cryogenic gas to be discharged into the atmosphere. The junction may also be configured to connect the first passage to a source of heated gas, such as helium.

[0015] The shaft may additionally include a protective cover proximal to the reinforcing element. The cover is configured to allow the shaft to flex, but to reduce or prevent kinking of the shaft. The protective cover may extend distally beyond the most proximal portion of the reinforcing element and may cover at least a portion of the tail region extending proximally from the reinforcing element.

[0016] The first passage is usually defined by and coextensive with an inlet pipe having an outer peripheral wall. The first passage provides high pressure gas to the expansion chamber from a source of refrigerated gas (or heated gas). Preferably, the first passage extends into the expansion chamber and terminates in the chamber at or near its farthest end. The inlet pipe extends proximally to the proximal end of the tail region. The inlet pipe usually terminates in a connector, as described above.

[0017] The inlet tube is sized to fit within the second passage and have sufficient cross-sectional area of ​​the second passage to provide effective discharge of the gas. Therefore, the diameter of the inlet tube can be determined by the flow characteristics required for the device. Depending on the desired outer diameter of the device, the outer diameter of the inlet tube can be, for example, 0.25 to 0.5 mm, preferably 0.3 to 0.4 mm. The diameter of the first passage can be 0.15 to 0.25 mm, preferably 0.15 to 0.2 mm.

[0018] The inlet pipe is typically metallic and may, for example, be made of stainless steel.

[0019] High pressure gases suitable for use as cryogenic gases or cryogenic fluids include CO2, argon, nitrogen, krypton, CF4, xenon or N2O; preferably, the cryogenic gas is argon. As used herein, the term "high pressure" as applied to a gas refers to a gas pressure suitable for Joule-Thomson cooling of a cryoprobe. In the case of argon, for example, "high pressure" argon is typically between 3000 psi and 4500 psi, although slightly higher and lower pressures may sometimes be used.

[0020] The expansion of a high pressure gas through a Joule-Thomson orifice can also be used to provide heating. Certain gases ("heating gases") become warmer rather than cooler when passing through a Joule-Thomson orifice (e.g., when passing at room temperature or higher). Helium is an example of a gas with this property. Thus, passing helium through a Joule-Thomson orifice has the effect of warming the probe tip and accelerating tissue melting.

[0021] The first passage terminates in a Joule-Thomson orifice at its distal end, which may be located within an expansion chamber in the operating head. When high pressure gas is supplied through the first passage and exits through the Joule-Thomson orifice, it expands, causing it to cool. The cooled expanding gas and any liquefied gas formed cools the outer surface of the operating head and thereby freezes adjacent body tissue to produce the desired cryoablation effect.

[0022] The first passage is also capable of conveying a heating gas, such as helium. The heating gas has a lower transition temperature than the temperatures obtained by liquefying the cooling gas, or a negative Joule-Thomson coefficient at temperatures as low as those obtained by liquefying the cooling gas. Therefore, the first passage is configured to be connectable to a first gas source supplying high pressure cooling gas, and also to a second gas source supplying high pressure heating gas. Because switching between gas sources is typically controlled by a control unit, the first and second gases can be connected through the same proximal joint.

[0023] Therefore, the cryoprobe according to the present invention can quickly switch from cooling to heating to increase the speed of surgery and more easily prevent the operating head from adhering to the tissue. The cryoprobe can also cause rapid cyclic temperature changes in the cryoprobe, so that the temperature of the probe quickly alternates between a temperature of about 0°C and a temperature below -40°C.

[0024] The second passage evacuates gas from the expansion chamber toward the discharge device. The second passage is usually defined by and coextensive with an outlet pipe, which evacuates gas and has an inner circumferential wall and an outer circumferential wall. The second passage is coaxially arranged around the first passage so that the first and second passages can share a common circumferential wall, wherein the inner circumferential wall is the same as the outer circumferential wall of the inlet pipe. Preferably, the proximal end of the second passage is open to the atmosphere.

[0025] The second passage has a sufficient cross-sectional area to allow effective recirculation of the exhaust gas, so the diameter of the outlet pipe can be determined by the flow characteristics required for the device. This provides a simple counter-flow recuperative heat exchanger. Depending on the desired outer diameter of the device, the diameter of the second passage can be, for example, 0.6 to 1.2 mm, preferably 0.7 to 0.8 mm.

[0026] The outlet tube is typically metallic and may, for example, be made of stainless steel.

[0027] The coaxial arrangement of the first and second passages acts as a simple heat exchanger. The expanding gas at the proximal end of the second passage is cooler than the high pressure gas in the first passage at that point and therefore cools the high pressure refrigerated gas supplied towards the expansion chamber. The arrangement also provides a positive feedback mechanism whereby during continued use, the refrigerated gas supplied through the first passage becomes increasingly cooler, as does the gas exhausted via the second passage.

[0028] When the cooled expanded gas returns via the second passage formed around the circumference of the inlet pipe, it cools the gas introduced in the inlet pipe in a simple counter-current heat exchange mechanism.

[0029] Thus, the device may comprise a single heat exchange configuration involving the exchange of thermal energy between inlet and outlet tubes arranged linearly and concentrically within the shaft. This arrangement allows the shaft itself to have a uniform diameter from the proximal end to the distal end.

[0030] This serves as the only heat exchange mechanism necessary to form the ice ball around the tip of the device. Due to the size of the probe and the smaller size of the ice ball produced, an additional heat exchanger is no longer required. For example, a spiral coil heat exchanger commonly found in cryoablation devices is not necessary. This saves weight in the handle of the device where the heat exchange arrangement is usually located.

[0031] The second passage extends from the proximal end of the outlet tube to the distal end, wherein there are no additional heat exchange features. Likewise, the first passage extends from the proximal end of the inlet tube to the distal end, wherein there are no additional heat exchange features. Thus, the inlet tube extends proximally from the junction to the farthest end located in the expansion chamber, and the outlet tube extends distally from the vent to the atmosphere (generally from the junction) to the operating head, wherein there is little or no interference with the flow in either tube.

[0032] Due to the lack of other heat exchange structures, the resistance to the flow of the refrigerant gas through the first passage is uniform throughout the shaft, and the resistance to the flow of the returning refrigerant gas in the second passage is uniform throughout the shaft. Neither the flow in the inlet pipe nor the flow in the outlet pipe is affected (e.g., blocked, diverted, split, or slowed) by a heat exchange structure with another pipe, such as a spiral heat exchanger.

[0033] The vacuum chamber has an inner circumferential wall and an outer circumferential wall, whereby the outer circumferential wall defines the periphery of the elongated shaft of the probe. In some examples, the vacuum chamber is coaxially arranged around the first and second passages so that the vacuum chamber shares a circumferential wall with the second passage, for example, wherein the inner circumferential wall of the vacuum chamber is the same wall as the outer circumferential wall of the second passage. The vacuum chamber extends distally to the operating head, but does not extend above the operating head. This limits the scope of the ice ball to the distal end of the device, including the operating head, and protects the tissue around the more proximal portion of the shaft from the effects of low temperatures. This also allows the operator to safely handle the cryoprobe. The arrangement that the inner wall of the vacuum chamber also forms the outer wall of the second passage allows the device to be configured to minimize the diameter of the shaft and enable the cryoprobe to have very thin dimensions.

[0034] Preferably, the outlet tube extends distally beyond the distal-most extent of the vacuum chamber. This enables the distal-most end of the outlet tube to extend into the proximal chamber of the operating head and provides a secure mount for attaching the operating head. Preferably, the inlet tube extends beyond the distal-most end of the outlet tube into an expansion chamber formed beyond the distal-most end of the outlet tube.

[0035] Preferably, the outer wall of the vacuum chamber is tapered at its distal end so that the tapered end of the vacuum chamber forms a junction with the outer wall of the outlet pipe. This provides a circumferential recess between the outer wall of the vacuum chamber and the operating head. Preferably, the outer wall of the vacuum chamber is a push fit on the outlet pipe. This allows easy assembly of the device and helps to minimize the overall outer diameter of the device. Preferably, the operating head is welded or brazed to the vacuum tube and / or the outlet pipe. This configuration allows the outer wall of the vacuum tube to be easily attached to the outer wall of the outlet pipe. In one method, the outer wall of the vacuum sleeve is welded or brazed to the outer wall of the outlet pipe in the vacuum furnace before it is attached to the operating head.

[0036] Preferably, the surface of the operating head and the outer tube of the vacuum sleeve provide a continuous surface of uniform diameter. The presence of a circumferential notch between the operating head and the outlet tube and / or vacuum tube provides a secure welded or brazed joint and allows the device to have a continuous surface of uniform diameter. The joint is preferably laser welded.

[0037] The operating head is preferably formed of a single solid piece of material (e.g., as an integral unit). The operating head includes a chamber that is open at the proximal end and has a chamber wall that surrounds the chamber and extends from the proximal end of the operating head to the distal end of the chamber. The proximal chamber of the head is generally 1 to 3 mm deep, preferably 1 to 2 mm deep. The diameter of the head is approximately the same as the diameter of the shaft to provide a smooth and uniform outer surface. On the distal side of the chamber, the operating head is solid. The operating head can have a blunt distal end, but preferably, the operating head has a sharp distal end that is configured to penetrate tissue, preferably in the form of a three-sided trocar-type top. The length of the operating head measured from the top to the nearest point on the chamber wall is generally between 2 and 10 mm. The proximal portion of the chamber wall preferably forms a joint with the distal end of the outlet tube. Preferably, the inner surface of the proximal portion of the chamber wall forms a joint with the outer surface of the distal end of the outlet tube, preferably as a push fit. The expansion chamber of the device is formed between the distal end of the chamber and the distal end of the outlet tube. The chamber is defined by the chamber wall.

[0038] Preferably, the length of the operating head measured from the point where the operating head meets the farthest end of the vacuum chamber to the far end of the operating head is 2 to 7 mm (e.g. Figure 1 Preferably, the length of the operating head is 2.5 to 6 mm, and more preferably, the length of the operating head is 4 mm + / - 1.5 mm.

[0039] Preferably, the operating head is formed of a thermally conductive material, such as a metal, for example, stainless steel, to effectively freeze body tissue in contact with the operating head. In one embodiment, the operating head has an outer sheath layer, which is also preferably formed of a thermally conductive material.

[0040] The probe comprises an elongated reinforcing element, which is positioned toward the distal end of the elongated shaft. The element is used as a support for the shaft during manipulation, and is configured to reduce and preferably prevent the flexure of the elongated shaft over the length of the reinforcing element during use. In other cases, the shaft has considerable ductility due to the thinness of the wall of the tubular element (inlet pipe, outlet pipe and outer wall of the vacuum chamber) constituting the shaft. The reinforcing element is elongated along the axis of the shaft to provide sufficient support for the shaft. The reinforcing element can be used as a handle for manipulating the shaft. It is usually fixedly engaged with the shaft to prevent the shaft from moving relative to the element when the top is pushed into the tissue. In one arrangement, the reinforcing element is arranged around the shaft, for example, it can be coaxially and / or circumferentially arranged around the shaft. For example, it can be a reinforcing tube coaxially arranged around the shaft.

[0041] The reinforcing element may be in the form of a handle or grip, or a handle may be provided in addition to the reinforcing element. The handle also serves to improve the grip of the shaft. Typically, the handle may be coaxial with the elongated shaft. Preferably, its diameter is greater than the diameter of the vacuum cannula and is typically of a size and shape suitable for comfortable hand gripping. The handle not only serves to provide a portion suitable for manipulating the probe, but also reinforces the shaft at this point to prevent bending while manipulating it. The handle may be provided with an insulating layer, which may be an insulating material, an additional vacuum chamber, or a combination thereof, or both. The handle may be provided with a polymer sheath to assist in gripping the device during manipulation. The sheath may also be used to carry identification markings of the device, such as the size and type of probe.

[0042] The cryoablation devices of the present invention may be provided with a straight shaft or an angled shaft, wherein the shaft is bent to provide less crowding at the insertion site, typically with an approximately right angle bend.

[0043] Typically, the inlet and outlet pipes are continuous through the handle portion of the device. Preferably, they extend beyond the proximal extent of the handle to provide a high pressure gas inlet and a low pressure gas return line, respectively. The high pressure gas inlet preferably terminates proximally in a connector adapted to be connected to a source of refrigerated gas. The return line preferably terminates at an opening to release the returned gas to the atmosphere.

[0044] The outer wall of the vacuum chamber may extend through the handle portion. It may extend further proximally to insulate at least a portion of the gas return line proximal to the handle. The high pressure gas inlet and low pressure gas return line (and the vacuum chamber, if any) may be provided with an outer protective tube to prevent damage to the lines.

[0045] In another aspect of the invention, a system for cryoablation is provided, comprising one or more cryoprobes as described herein. Typically, such a system comprises one or more cryoprobes, such as cryonellary needles, suitable for percutaneous use; one or more sources of cryofluids; and a control system. The cryosurgical system can be used to cryoablate a target tissue (e.g., a tumor). By selecting an appropriate cryofluid and pressure, it can be used to cool the tissue more or less.

[0046] The cryogenic fluid source can supply a gas, such as argon, nitrogen, air, krypton, CO2, CF4, xenon, and various other gases, that can reach cryogenic temperatures (e.g., temperatures below 190 Kelvin) when expanded from a pressure greater than about 1000 psi. As used herein, a "cryogenic fluid" can refer to any fluid that reaches cryogenic temperatures (e.g., below 190 Kelvin) when expanded from a pressure greater than about 1000 psi (e.g., typically about 3500 psi). The source can include one or more valves and / or regulators to control the flow of the cryogenic fluid and the heating fluid.

[0047] The control system is configured to control the delivery of the cryofluid to the cryoprobe and may include, for example, one or more sensors, flow meters, timers, analog / digital converters, wired or wireless communication modules, valve controllers, etc. Additionally, the control system may also adjust the flow rate, temperature, and pressure of the cryofluid supplied to the cryoprobe.

[0048] In another embodiment, a method of ablating patient tissue is provided, comprising placing the tip of a cryoprobe as described herein in, at, or near the tissue to be ablated; delivering a cryogenic gas to a Joule-Thomson orifice via a first passage at a pressure sufficient to cause cooling of the tip of the probe to a cryogenic temperature and thereby freezing patient tissue in contact with the tip of the probe; and subsequently melting the tissue.

[0049] The tissue is at least thawed sufficiently so that the probe can be removed if necessary, however, several freeze and thaw cycles are typically performed, e.g., two, three or more cycles. In an alternative approach, heated gas is delivered to the Joule-Thomson orifice at a pressure sufficient to cause warming of the probe tip and thereby melting of the tissue, rather than allowing the tissue to melt naturally.

[0050] Typically, the freezing operation forms a "ball of ice" of frozen tissue around the tip of the probe.

[0051] In some methods, a cooling gas, such as nitrous oxide, may be used instead of a cryogenic gas. The expansion of these gases as they exit the Joule-Thomson orifice does not result in cooling to cryogenic temperatures, but rather in temperatures low enough to cause disruption or damage to the tissue, rather than killing it. This approach is particularly useful when the probe is used for cryoneurolysis of neural tissue, which can continue to grow after exposure to such temperatures, rather than after exposure to cryogenic temperatures.

[0052] One or more cryoprobes are placed at or near the tissue to be treated by ablation. High pressure gas, such as argon, is delivered to the cryoprobe to form an ice ball at the tip of the probe that surrounds the tissue to be treated. Imaging procedures, such as ultrasound or MRI, can be used to track the formation of the ice ball, and when the ice ball reaches the desired size, cooling is stopped. The ice ball can then be melted naturally using body temperature, or melting can be accelerated by delivering a heated gas, such as helium, to warm the tip of the probe. Helium melting is preferred because it is faster.

[0053] Typically, one or more ice ball formation and melting cycles are used to ablate the target tissue. Typically, one, two or three cycles are used.

[0054] Cryoablation of tumors is known to produce abscopal effects in lesions far from those treated. In the case of a tumor ablated using cryoablation, other tumors far from the first tumor have been observed to shrink. It is believed that this effect is mediated by the release of tumor antigens, which infuse the immune system to recognize distant tumors (see, e.g., Mehta et al., Gastroenterology Research and Practice, Vol. 2016, Article ID: 9251375).

[0055] As a result of these observations, the use of a combination of cryoablation and various immunomodulatory agents has been proposed for the treatment of tumors (see, e.g., Abdo et al., 2018, Frontiers in Oncology, Vol. 8, Article 85).

[0056] In one treatment approach, cryoablation of the tumor can be used in combination with immunomodulatory drugs administered before, during, or after the cryoablation therapy. Such drugs include checkpoint inhibitors, such as anti-CTLA-4, anti-PD-1, and anti-PDL-1 antibodies, including, for example, ipilimumab, nivolumab, pembrolizumab, atezolizumab, avelumab, and durvalumab.

[0057] The present probe is also particularly suitable for treating pain by partial (axotomy) or complete ablation (neurotomy) of nerves.

[0058] By utilizing a cryoprobe in which the elongated shaft has a reduced size (e.g., a cryoprobe of the present invention having a reduced shaft length and diameter), the number of cryoprobes present at the ablation site can be reduced because crowding is reduced. Given that an increased number of cryoprobes can be fitted into a given area, this further enhances the ability to accurately carve a three-dimensional ablation target site. Furthermore, by using a combination of straight and curved cryoprobes, an even greater number of cryoprobes can be deployed in a given area at the ablation site, thereby further reducing crowding when multiple cryoprobes are deployed.

[0059] The small diameter and short length also allow the probe to be used to access small volumes of tissue where a normal probe would be difficult or impossible to use accurately. It is particularly useful for treating conditions in infants.

[0060] Another particular condition that may be treated using the probe of the present invention is Morton's neuroma, a benign neuroma of the inter-metatarsal plantar nerve that is inaccessible to standard probes due to its size. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Various aspects of the present invention will now be further described by the following non-limiting examples with reference to the accompanying drawings. These contents are provided for illustrative purposes only, and in view of these contents, other examples falling within the scope of the claims will be apparent to those skilled in the art. All literature references cited herein are incorporated herein by reference.

[0062] Figure 1 is a simplified illustration of features of the cryoprobe shaft shown in cross-section. Figure 1A The joint arrangement between the operating head and the shaft is shown at a higher magnification.

[0063] Figure 2 is a pictorial view of the curved axis arrangement of the cryoprobe.

[0064] Figure 3 is a simplified illustration of features of an example cryoprobe with a stiffening element. The device is shown in cross section.

[0065] Figure 4 is a simplified illustration of features of a cryoprobe having another example of a stiffening element. The device is shown in cross section.

[0066] Example

[0067] A cryoneer was constructed according to the above description, having an inlet tube with an inner diameter of 0.18 mm and an outer diameter of 0.33 mm. An outer tube with an inner diameter of 0.72 mm and an overall diameter of 1.2 mm included a vacuum cannula. The length of the operating head was approximately 5 mm. The length of the entire device from the tip to the proximal end of the tail was 3 m, and the combined shaft and operating head extended 30 mm from the reinforcing element.

[0068] Using argon delivered at 3500 psi, these needles produced ice balls with a diameter of 10 mm at 2 minutes, 14 mm at 3.5 minutes, and 15 mm at 5 minutes. DETAILED DESCRIPTION

[0069] Attached photos

[0070] Figure 1 A simplified view of a cross section through a cryoprobe 1 is shown. The cryoprobe 1 has an elongated shaft 2 including an operating head 5 having a top end 16. The elongated shaft 2 encloses a first passage 3 coextensive with an inlet tube 17. A second passage 4 coextensive with an outlet tube 18. The first passage 3 and the second passage 4 are concentric, wherein the second passage 4 surrounds the first passage 3. The second passage 4 can be opened proximally to atmosphere via an outlet 19.

[0071] The operating head 5 includes an operating head proximal chamber 20, which is surrounded by a chamber wall 21 and is distally surrounded by a distal wall 25. The outlet tube 18 can extend into the proximal chamber 20 of the operating head 5. The expansion chamber 6 can be formed between the distal end 24 of the outlet tube 18 and the distal wall 25 of the operating head proximal chamber 20. The expansion chamber can be defined by the inner wall 23 of the operating head proximal chamber 20. The distal end 26 of the inlet tube 17 generally protrudes into the expansion chamber 6 and can terminate in the Joule-Thomson orifice 7 formed at the distal end of the first passage 3.

[0072] The inlet pipe 17 is configured to deliver cryogenic gas under pressure from a cryogenic fluid source (not shown in this figure). The cryogenic gas expands when leaving the Joule-Thomson orifice 7 and is exhausted to the atmosphere at an opening 19 via the outlet pipe 18 .

[0073] The elongated shaft 2 also includes a vacuum chamber 8, which is externally bounded by an outer circumferential vacuum chamber wall 27 and internally bounded by the wall 22 of the outlet tube 18. The vacuum chamber is configured to thermally insulate the shaft proximal to the operating head and thus prevent tissue damage proximal to the intended ice ball. Distally, the vacuum chamber wall 27 is tapered 14 and push fits over the outlet tube 18 at this point to provide a joint between the two tubes 41. The vacuum chamber wall 27 can be welded or brazed to the wall of the outlet tube 18 in a vacuum furnace before being attached to the operating head. The distal-most end 24 of the outlet tube 18 can protrude beyond the tapered end of the wall of the vacuum chamber 14 so as to be insertable into the proximal portion 28 of the proximal chamber 20 of the operating head. The proximal end 29 of the wall 21 of the proximal chamber 20 of the operating head can abut against the distal end 30 of the vacuum chamber outer wall 27 to provide a circumferential gap 31 between the vacuum chamber outer wall 27 and the proximal end 29 of the distal chamber wall 21 of the operating head. The operating head 5, vacuum chamber outer wall 27 and outlet tube 18 may be welded or brazed together at this point 15 to seal the vacuum tube and hold the head in place.

[0074] Figure 1A A close-up view of the joint between the operating head and the elongated shaft is shown. Figure 1 same.

[0075] Figure 2 A cryoprobe 1 having a shaft 2 and a distal operating head 5 is shown. The shaft is in a bent configuration, which helps prevent overcrowding at the insertion site when more than one device is used. The shaft has a handle region 103, which has an outer diameter greater than the shaft, and the handle region 103 is covered in a heat shrink wrap 155. The shaft 2 extends proximally to the handle 103 as a tail region 150. In this region, the shaft is covered by a wrap extending from the handle 103 to a proximal connector 151, which is configured to connect the first passage to a source of cryogenic fluid (not shown). The connector also includes a distal outlet of a second passage via an outlet 19, which is used to discharge low-pressure gas to the atmosphere 300. The connector also includes an inlet 301 for connecting to a high-pressure gas source.

[0076] Figure 3 A cross section through the cryoprobe is shown to illustrate its features. The cryoprobe 1 has a handle 103 that facilitates manipulation of the probe and prevents flexure of the shaft and kinking of the shaft during insertion into tissue. The cryoprobe has an elongated shaft 2 that extends distally through the handle portion 103. An operating head 5 is provided distally of the elongated shaft 2. The shaft extends proximally from the handle 103 in the form of a tail 150 that terminates in a fitting 151 configured to connect the first passage 3 to a source of cryofluid (not shown).

[0077] The elongated shaft 2 encloses a first passage 3 that is coextensive with an inlet tube 17. A second passage 4 is coextensive with an outlet tube 18. The second passage 4 may open proximally to atmosphere, for example, via an outlet 19. A distal-most end 26 of the inlet tube 17 typically protrudes into the expansion chamber 6 and may terminate in a Joule-Thomson orifice 7 formed at a distal-most end 32 of the first passage 3.

[0078] The inlet pipe 17 is configured to deliver cryogenic gas under pressure from a cryogenic fluid source (not shown in this figure). The cryogenic gas expands when leaving the Joule-Thomson orifice 7 and is exhausted to the atmosphere at an opening 19 via the outlet pipe 18 .

[0079] A vacuum chamber 8 is formed above the outlet tube 18 and is peripherally bounded by a peripheral vacuum chamber wall 27. The vacuum chamber is configured to thermally insulate the shaft proximal to the operating head and thus prevent tissue damage proximal to the intended ice ball.

[0080] The shaft 2 extends through the handle portion 103 and may be continuous with the tail 150, as shown, or may form a joint with a removable tail (not shown).

[0081] The handle portion 103 has a larger diameter than the vacuum chamber wall 27 and provides a reinforced area of ​​the shaft that prevents the shaft from flexing during manipulation and thus prevents the shaft from kinking. In one arrangement, the handle portion includes a sleeve 104 having a larger diameter than the vacuum chamber wall 27. The sleeve 104 can be metal or polymer. In one approach, the sleeve can have tapered regions 164, 165 that provide a gradual reduction in sleeve diameter and provide a push fit on the vacuum chamber wall 27. The handle 103 can include a space 106 between the sleeve 104 and the vacuum chamber wall 27. The tapered regions 164, 165 of the sleeve are particularly useful in this case, particularly in the case where the sleeve is metal, because it allows a thin metal sleeve to provide a wide handle portion with minimal weight and provides reinforcement to the sleeve. Where there is a space 106, it can be evacuated to provide additional insulation. The area between the vacuum chamber wall and the sleeve can also be filled with insulating material.

[0082] The tail 150 may be provided with a cover 107 that generally extends from at least the handle 103 to a proximal portion 152 of the tail 150. The cover 107 provides protection to the tail 150 and reduces kinking within the tail. The cover 107 may be loosely disposed over the vacuum sleeve wall 27 within the tail region 150 or may be processed to the vacuum sleeve wall 27. A cladding 155 may be disposed over the sleeve to seal the sleeve to the vacuum chamber wall 27. It may also extend to hold the distal end 154 of the cover 107 in place. For example, the cladding 155 may include a heat shrink sleeve.

[0083] Figure 4 Another embodiment of the handle portion is shown. The cryoprobe 1 has a handle 103 for manipulating the probe so as to prevent flexing of the probe and thereby prevent kinking of the shaft 2 during use. The cryoprobe has an elongated shaft 2, which extends distally through the handle portion 103 and from the handle portion 103. An operating head 5 is provided distally of the elongated shaft 2. The shaft extends proximally from the handle 103 in the form of a tail 150, which terminates in a fitting 151 configured to connect the first passage 3 to a source of cryogenic fluid (not shown). The elongated shaft 2 surrounds the first passage 3 extending together with the inlet tube 17. The second passage 4 extends together with the outlet tube 18. The second passage 4 can be opened proximally to the atmosphere. The farthest end 26 of the inlet tube 17 usually protrudes into the expansion chamber 6 and can terminate in the Joule-Thomson orifice 7 formed at the farthest end 32 of the first passage 3.

[0084] Inlet pipe 17 is configured to deliver cryogenic gas under pressure from a cryogenic fluid source (not shown in this figure). The cryogenic gas expands when leaving the Joule-Thomson orifice 7 and is exhausted to atmosphere at a distal opening (not shown in this figure) via outlet pipe 18.

[0085] A vacuum chamber 8 is formed above an outlet tube 18 which is externally bounded by a peripheral vacuum chamber wall 27. The vacuum chamber is configured to thermally insulate the shaft proximal to the operating head 5 and thus prevent tissue damage proximal to the intended ice ball.

[0086] The shaft 2 extends through the handle portion 103 and may be continuous with the tail 150, as shown, or may form a joint with a removable tail (not shown) that provides connection to a source of cryogenic fluid and optionally to a proximal gas evacuation port.

[0087] The handle portion 103 has a larger diameter than the vacuum chamber wall 27 and provides a reinforced area of ​​the shaft that prevents flexing of the shaft and protects the shaft during handling. In one arrangement, the handle portion 103 includes a first sleeve 130 having a larger inner diameter than the vacuum chamber wall 27. The sleeve 130 fits over the vacuum chamber wall and provides additional rigidity to the shaft. A cylindrical cover 155 may be disposed on the first sleeve and extend proximally over a proximal end 156 of the first sleeve 155 to cover at least a portion of the tail 150. Preferably, the cover 155 extends to the proximal end of the tail (not shown here).

[0088] The first sleeve 130 and the cap 155 can be held in place by a handle nose 157, which is typically a polymer material, such as polypropylene or PEEK, that extends circumferentially around the vacuum sleeve wall 27 at a distal end 158 of the handle and is configured to receive a distal-most end 162 of the second sleeve 161 in a position axially outward of the first sleeve 130. This allows for a wider sleeve and therefore a wider handle for easier manipulation. The handle nose 157 extends circumferentially around the shaft 2 and may also extend circumferentially around a distal end 159 of the first sleeve 130 and a distal end 160 of the cap 155.

[0089] The proximal end 166 of the second sleeve 161 may be received in a similar manner by a handle butt 163 that extends circumferentially around the vacuum sleeve wall 27 at the proximal end 164 of the handle.

[0090] The handle portion 103 may include a space 106 axially inward from the second sleeve 161 , which may optionally be filled with an insulating material, but is preferably empty to provide a lighter handle.

[0091] An outer coating (not shown in this figure) may extend over the sleeve and optionally over at least a portion of the nose and tail to provide a smooth surface to the handle. Again, heat shrink tubing is useful in this regard.

Claims

1. A cryoprobe, comprising: an elongated shaft having a distal end and a proximal end; an operating head at the distal end of the elongated shaft, wherein the operating head includes an expansion chamber; The elongated shaft comprises: a first passage configured to provide high pressure gas to the expansion chamber and wherein the first passage terminates in a Joule-Thomson orifice at a distal end thereof; a second passage for exhausting gas from the expansion chamber, wherein the second passage is coaxially arranged around the first passage; and a vacuum chamber coaxially disposed around the first passage and the second passage; The cryoprobe additionally includes an elongated stiffening element positioned toward the distal end of the elongated shaft, the elongated stiffening element being configured to reduce deflection of the elongated shaft; The reinforcing element includes a handle portion having a larger diameter than the vacuum chamber wall, the handle portion also having a tapered region, the tapered region providing a diameter of the handle portion that gradually decreases toward the vacuum chamber wall, the handle portion being arranged to surround the elongated shaft so that the handle portion is separated from the vacuum chamber wall. 2 . The cryoprobe according to claim 1 , wherein the cross-section of the elongated shaft has a diameter of 0.9 to 2.0 mm.

3. The cryoprobe of claim 1 or 2, wherein the combined shaft and operating head extends distally beyond the reinforcing element up to 100 mm. The cryoprobe of claim 1 , wherein the stiffening element is coaxially disposed around the elongated shaft. The cryoprobe of claim 1 , wherein the handle is configured for manipulating the cryoprobe. The cryoprobe of claim 5 , wherein the handle is hollow.

7. The cryoprobe according to claim 1 or 2, comprising a single heat exchange configuration consisting of heat energy exchange between the first passage and the second passage, the first passage and the second passage being linearly and concentrically arranged within the shaft.

8. The cryoprobe according to claim 1 or 2, wherein the operating head has a length of 2 to 7 mm.

9. A cryosurgery system comprising one or more cryoprobes according to any one of claims 1 to 8 and additionally comprising a source of cryofluid and a control configured to control delivery of the cryofluid to the cryoprobe.

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