Cryoprobe

Abstract

A cryosurgical device, such as a cryosurgical probe (cryoprobe), is disclosed. Some exemplary embodiments may include: an elongated shaft at least partially housing or defining a fluid supply conduit and a fluid exhaust conduit, the elongated shaft including a distal ablation section terminating at a closed distal end; a housing at least partially surrounding at least a portion of the proximal end of the elongated shaft and receiving or defining at least a portion of the fluid supply conduit and a portion of the fluid exhaust conduit; and / or a flow restriction element in fluid communication with the fluid exhaust conduit, the flow restriction element regulating fluid flow through at least a portion of the fluid exhaust conduit.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 731,310, filed September 14, 2018, which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to cryoprobes, and more particularly, to cryoprobes having an extendable shaft interconnecting an ablation tip and a handle control. Summary of the invention

[0004] The present disclosure contemplates that the temperature of the ablation tip of a cryoprobe may be related to the boiling temperature (e.g., vaporization temperature) of the refrigerant, which may be related to the refrigerant pressure at the ablation tip. The present disclosure contemplates that, for example, in a cryoprobe where the back pressure in the refrigerant exhaust stream varies, the refrigerant pressure at the ablation tip may vary significantly, thereby affecting the temperature of the ablation tip. The present disclosure provides methods and apparatus for improving the regulation of the refrigerant exhaust stream back pressure. In addition, the present disclosure contemplates that the refrigerant pressure at the ablation tip may be affected by the characteristics of the flow path leading to the ablation tip. The present disclosure provides methods and apparatus for improving the supply of refrigerant to the ablation tip to achieve a desired temperature. In this way, the present disclosure provides an improvement over the prior art relating to temperature regulation at the ablation tip of a cryoprobe.

[0005] The present disclosure contemplates that, although a cryoprobe may utilize extremely cold temperatures to achieve a desired effect at a desired location, exposing other locations to extremely cold temperatures may result in undesirable effects. The present disclosure contemplates that, for example, it may be desirable for the ablation tip of a cryoprobe to be extremely cold while the shaft on which the tip is disposed remains above the tissue ablation temperature. The present disclosure provides methods and apparatus for improving the ability of a cryoprobe to cool the ablation tip to a desired temperature while maintaining other external portions of the cryoprobe at a warmer temperature. In this manner, the present disclosure provides improvements over the prior art associated with cryoprobes.

[0006] The present disclosure contemplates that the rate of heat transfer and / or the extent of ablation may depend on the manner in which the cryoprobe engages the target tissue. For example, the present disclosure contemplates that the configuration of the cryoprobe may affect the difficulty of approaching, engaging, and ablating a particular tissue to a desired degree. The present disclosure provides methods and apparatus relating to cryoprobe configurations suitable for achieving desired tissue ablation (such as cryoanalgesia of intercostal nerves). In this manner, the present disclosure provides improvements in the prior art related to cryoprobes, for example, cryoprobes may be used for cryoanalgesia.

[0007] A first aspect of the present disclosure is to provide a cryogenic probe comprising: an elongated shaft at least partially accommodating or defining a fluid supply conduit and a fluid discharge conduit, the elongated shaft including a distal ablation section terminating at a closed distal end; a shell at least partially defining at least a portion of the proximal end of the elongated shaft and receiving or defining at least a portion of the fluid supply conduit and a portion of the fluid discharge conduit; and / or a flow restriction element fluidly connected to the fluid discharge conduit, the flow restriction element regulating the flow of fluid through at least a portion of the fluid discharge conduit.

[0008] In an embodiment, the flow restriction element may include a constriction fluidly inserted between the fluid discharge conduit and the discharge line. The cross-sectional area of ​​the constriction for fluid flow may be less than about 70% of the cross-sectional area of ​​the discharge line for fluid flow. The cross-sectional area of ​​the constriction for fluid flow may be less than about 50% of the cross-sectional area of ​​the discharge line for fluid flow. The cross-sectional area of ​​the constriction for fluid flow may be less than about 30% of the cross-sectional area of ​​the discharge line for fluid flow. The cross-sectional area of ​​the constriction for fluid flow may be less than about 15% of the cross-sectional area of ​​the discharge line for fluid flow. The cross-sectional area of ​​the constriction for fluid flow may be about 10% of the cross-sectional area of ​​the discharge line for fluid flow.

[0009] In an embodiment, the flow restriction element may include a pressure valve in fluid communication with the fluid supply conduit and the fluid exhaust conduit, the pressure valve regulating the flow of fluid through at least a portion of the fluid exhaust conduit. The pressure valve may include a valve plug configured to engage a valve seat and form a seal therebetween. The valve plug may be biased to engage the valve seat. The valve plug may be biased by a spring to engage the valve seat, and at least a portion of the spring may be located within the distal ablation segment.

[0010] In an embodiment, the distal ablation segment may include a spherical outer surface. The spherical outer surface may include a hemispherical portion. The distal ablation segment may include a necked segment to change the cross-section of the distal ablation segment. At least a portion of the fluid supply conduit may extend into the distal ablation segment. At least a portion of the fluid supply conduit extending into the distal ablation segment may include a fluid flow constriction before reaching a nozzle within the distal ablation segment. The proximal aspect of the distal ablation segment may be fluidly sealed to the distal aspect of the elongated shaft using at least one of adhesive bonding and fusion welding.

[0011] In an embodiment, the cryogenic probe may include a flexible, thermally insulated conduit that surrounds the elongated shaft along at least a portion of its longitudinal length. The flexible, thermally insulated conduit may define the elongated shaft along a majority of its longitudinal length. The flexible, thermally insulated conduit may include a spacer inserted between an outer covering of the flexible, thermally insulated conduit and the exterior of the elongated shaft. The spacer may include a foam, a spiral, and / or a plurality of polymer spirals. The polymer spirals may be longitudinally offset from one another along the flexible, thermally insulated conduit, and / or each polymer spiral may have a common axial dimension. The spacer may terminate before reaching at least one of the proximal and distal ends of the flexible, thermally insulated conduit. The flexible, thermally insulated conduit may be necked to have an outer major dimension that is less than the outer diameter of the spiral at at least one of the proximal and distal ends of the flexible, thermally insulated conduit.

[0012] In an embodiment, the elongated shaft may provide a bend greater than 180 degrees without breaking. The interior of the elongated shaft and the exterior of the fluid supply line may define a fluid exhaust line. The interior of the elongated shaft and the exterior of the fluid exhaust line may define a fluid supply line.

[0013] In embodiments, the bulbous outer surface may extend longitudinally more than half of the longitudinal length of the exposed outer surface of the distal ablation zone.The bulbous outer surface may extend longitudinally less than half of the longitudinal length of the exposed outer surface of the distal ablation zone.

[0014] In embodiments, the distal ablation zone may be configured to withstand pressure during a warming operation that includes blocking fluid flow through the fluid exhaust conduit.The housing may include an internal cavity housing an adapter operable to change the coaxial orientation of the fluid supply and fluid exhaust conduits to a parallel orientation.

[0015] A second aspect of the present disclosure is to provide a cryogenic probe comprising an elongated tube that at least partially accommodates or defines a fluid supply conduit and a fluid discharge conduit, the elongated tube comprising a distal ablation section terminating at a closed distal end, the elongated tube comprising at least one stagnant fluid sac inserted between the exterior of the conduit and at least one of the fluid supply conduit and the fluid discharge conduit; and / or a shell that at least partially defines at least a portion of the proximal end of the elongated tube and receives or defines at least a portion of the fluid supply conduit and a portion of the fluid discharge conduit.

[0016] In embodiments, the stagnant fluid pocket may be at least partially defined by a spacer spiral. The spacer spiral may include a plurality of spacer spirals. The plurality of spacer spirals may be longitudinally offset from one another along the length of the catheter. The spacer spiral may include an insulating material.

[0017] In an embodiment, the at least one stagnant fluid pocket may be at least partially defined by an insert that also provides a passage for at least one of a fluid supply conduit and a fluid exhaust conduit. The insert may include a triangular cross-section and / or may include separate passages for the fluid supply conduit and the fluid exhaust conduit. The separate passages for the fluid supply conduit and the fluid exhaust conduit may include at least one of a plurality of fluid supply conduits and a plurality of fluid exhaust conduits. The insert may include a geometric cross-section and / or may include separate conduits for the fluid supply conduit and the fluid exhaust conduit, the geometric cross-section having four or more sides. The separate conduits for the fluid supply conduit and the fluid exhaust conduit may include at least one of a plurality of fluid supply conduits and a plurality of fluid exhaust conduits.

[0018] The third aspect of the present disclosure is to provide a cryogenic probe, which includes a slender tube, the slender tube includes an insulating section that at least partially accommodates or defines a fluid supply conduit and a fluid discharge conduit, the slender tube includes a distal ablation section terminating at a closed distal end, the fluid supply conduit is close to the closed distal end and terminates within the distal ablation section, the cross-section of the fluid supply conduit at the terminal end is significantly smaller than the cross-section upstream of the terminal end; and / or a shell, which at least partially surrounds at least a portion of the proximal end of the slender tube and receives or defines at least a portion of the fluid supply conduit and a portion of the fluid discharge conduit.

[0019] In embodiments, the cross-section of the fluid supply conduit at the terminal end may be defined by at least one of a fluid flow feature and a nozzle having a cross-section substantially smaller than the cross-section of the fluid supply conduit upstream of the terminal end.

[0020] A fourth aspect of the present disclosure is to provide a method for providing cryoanalgesia, the method comprising positioning a bulbous distal outer surface of an ablation tip of a cryoprobe in close proximity to a target nerve, the target nerve comprising an axon and surrounding tubular structures; destroying the axon of the target nerve by delivering a cryogenic fluid to the cryoprobe to cool the ablation tip while keeping at least some of the surrounding tubular structures intact; warming the cryoprobe; and / or removing the bulbous distal outer surface from close proximity to the target nerve.

[0021] In an embodiment, positioning the spherical distal outer surface of the ablation tip of the cryoprobe in close proximity to the target nerve may include placing the spherical distal outer surface of the ablation tip in direct contact with the target nerve. Positioning the spherical distal outer surface of the ablation tip of the cryoprobe in close proximity to the target nerve may include placing the spherical distal outer surface of the ablation tip close to the target nerve but not in direct contact with the target nerve. Warming the cryoprobe may include blocking the flow of discharged cryogenic fluid from the cryoprobe while continuing to supply the cryogenic fluid to the cryoprobe. The ablation tip may include a proximal outer surface of the ablation tip having a substantially constant axial profile, whose diameter is less than the diameter of the spherical distal outer surface. The spherical outer surface may include a hemispherical surface having a diameter between approximately 3.0 mm and approximately 18.0 mm. The method may include repeating the positioning, destroying, warming, and removing operations on a second target nerve. The target nerve may include an intercostal nerve. The method may include bending the cryoprobe before positioning the spherical distal outer surface of the ablation tip of the cryoprobe in close proximity to the target nerve. Destroying axons of a target nerve while leaving at least some surrounding tubular structures intact may include leaving at least one of the endoneurium, perineurium, nerve bundles, and epineurium intact.Destroying axons of a target nerve while leaving at least some surrounding tubular structures intact may include leaving the endoneurium and perineurium intact. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a side view of a first exemplary cryoprobe according to the present disclosure.

[0023] Figure 2 The handle housing is half removed to show Figure 1 2 is a side view of the internal components within the handle housing of a first exemplary cryoprobe.

[0024] Figure 3 yes Figure 1 Top view of the adapter and hypotube of the first exemplary cryoprobe.

[0025] Figure 4 It is cut along the main dimension and longitudinal length Figure 3 Cross-sectional view of .

[0026] Figure 5 yes Figure 2 A cross-sectional view of an exemplary adapter and related components is depicted.

[0027] Figure 6 yes Figure 1 0 is a longitudinal cross-sectional view of a first exemplary cryoprobe taken at a distal opening of a handle housing.

[0028] Figure 7 It is taken along the transition length between the insulated pipe and the insulated conduit. Figure 1Longitudinal cross-sectional view of a first exemplary cryoprobe.

[0029] Figure 8 is a cross-sectional view of a first exemplary insulated conduit according to the present disclosure.

[0030] Fig. 9 is a longitudinal cross-sectional view of a first exemplary insulated conduit along a majority of the length of the insulated conduit.

[0031] Fig.10 is a longitudinal cross-sectional view of a first exemplary insulated catheter at its proximal end.

[0032] Fig.11 is a side view of a first exemplary spacer according to the present disclosure.

[0033] Fig.12 is an elevational perspective view of a first exemplary cryoprobe with the ablation tip and the insulated catheter in different bending positions.

[0034] Fig.13 is an elevational perspective view of a second exemplary insulated conduit according to the present disclosure.

[0035] Fig.14 is an axial cross-sectional view of a second exemplary insulated conduit surrounding a malleable shaft and a supply conduit.

[0036] Fig.15 yes Figure 1 A longitudinal cross-sectional view of a first exemplary cryoprobe taken at its distal end.

[0037] Fig.16 is a longitudinal cross-sectional view of a malleable shaft connected to an ablation tip using a first exemplary mounting technique.

[0038] Fig.17 is a longitudinal cross-sectional view of a malleable shaft connected to an ablation tip using a second exemplary mounting technique.

[0039] Fig.18 is a side view of an alternative exemplary ablation tip having a domed cylindrical shape.

[0040] Fig.19 is a side view of a further alternative exemplary ablation tip having a rounded conical shape embodied as a spherical contact surface.

[0041] Fig. 20 is a longitudinal cross-sectional view of an alternative adapter providing a fluid flow constriction that can be used to create back pressure at the ablation tip in accordance with the present disclosure.

[0042] Fig.21 is a longitudinal cross-sectional view of a second exemplary cryoprobe taken at its distal end.

[0043] Fig. 22 is an elevational perspective view of an exemplary boiler that may be part of a second exemplary cryoprobe.

[0044] Fig.23 It is shown by a dotted line Fig. 22 A front perspective view of a boiler having at least one hypotube extending therefrom to define a fluid flow channel.

[0045] Fig.24 is an axial cross-sectional view of a malleable shaft having a first exemplary longitudinal insert having a triangular shape with separate fluid flow paths and dedicated bladders along its longitudinal length.

[0046] Fig.25 is an axial cross-sectional view of a malleable shaft having a first exemplary longitudinal insert having a hexagonal shape with individual fluid flow paths and dedicated bladders along its longitudinal length.

[0047] Fig.26 is a process flow diagram depicting an exemplary process utilizing one or more exemplary cryoprobes of the present disclosure.

[0048] Fig. 27 is a graphical depiction of the thoracic cavity and associated tissues showing the positioning of the cryoprobe as part of a cryoanalgesia procedure in the intercostal region.

[0049] Fig.28 is a cross-sectional perspective view of a nerve being cryoanalgesic via a cryoprobe in accordance with at least some aspects of the present disclosure. DETAILED DESCRIPTION

[0050] Exemplary embodiments of the present disclosure are described and illustrated below to cover exemplary cryogenic probes, methods of making cryogenic probes, and methods of using cryogenic probes as part of a pain management program. Of course, it will be apparent to one of ordinary skill in the art that the embodiments discussed below are exemplary in nature and may be reconfigured without departing from the scope and spirit of the invention. However, for the sake of clarity and precision, the exemplary embodiments discussed below may include optional steps, methods, and features, which one of ordinary skill will recognize are not necessary conditions to fall within the scope of the present disclosure.

[0051] refer to Figure 1, a first exemplary cryoprobe (cryoprobe) 100 may include a distal ablation section 101 including an ablation tip 102 connected to a flexible or ductile elongated shaft 104 extending through a thermal insulator 106 and into a handle housing 108. By way of example, the distance between the ablation tip 102 and the handle housing 108 may vary depending on the intended application, but in an exemplary form, may range from approximately 4 to 30 inches. In an exemplary form, the thermal insulator 106 may be substantially rigid and fixedly mounted to the handle housing 108 so as to protect portions of the ductile shaft 104 from direct contact with the surrounding environment thereabout, including adjacent tissue when inserted into a mammal. In this exemplary embodiment, the handle housing 108 may include a pistol grip 110 and an internal cavity extending therethrough that accommodates a connection between the ductile shaft 104 and a connection bundle 112. In addition to the pistol grip 110, other gripping methods known in the art may be used.

[0052] In an exemplary form, the connection bundle 112 may include a braided sleeve 113 surrounding a supply line 114 that directs the working fluid from a fluid source (not shown) to the interior of the handle housing 108, and a drain line 116 that directs the working fluid from within the handle housing to a collection location (not shown), such as, but not limited to, a fluid recovery tank. In addition to the exemplary braided sleeve 113, other thicknesses and configurations of braided sleeves may be used to cover the supply line 114. Exemplary braided sleeves that may be used as part of the present disclosure include, but are not limited to, polyethylene terephthalate (PET) braided monofilament yarns, such as those available from TechFlex in Sparta, New Jersey. In addition, exemplary supply lines 114 and drain lines 116 that may be used as part of the present disclosure include, but are not limited to, micro-bore high-pressure hoses, such as those available from Hydrotechnik, England. In addition to the supply line 114 and the exhaust line 116, the braided sleeve 113 may also surround one or more thermocouple leads 118, which in an exemplary form are electrically connected to one or more thermocouples positioned within or adjacent to at least one of the ablation tip 102 and the extendable shaft 104. In addition, exemplary thermocouple leads 118 that may be used as part of the present disclosure include, but are not limited to, 24 AWG thermocouple wires available from Physitemp of Clifton, New Jersey. In this exemplary embodiment, the supply line 114 and the exhaust line 116 and the thermocouple leads 118 may be equipped with quick connect adapters 120 to make the cryoprobe 100 modular. In this manner, the cryoprobe 100 may be disposable and configured to interface with multiple or reusable components, such as, but not limited to, cryogenic fluid tanks, cryogenic fluid recirculators, and medical devices operable to display temperature readings.

[0053] refer to Figure 2-5In an exemplary form, the connection bundle 112 may extend into and terminate in a proximal opening 130 of the handle housing 108. In this exemplary embodiment, the handle housing 108 may include a right housing segment and a left housing segment that, when connected together, define an interior cavity and corresponding proximal openings 130 and distal openings 138. At the distal terminus of the connection bundle 112, a band 132 may surround the connection bundle end and the supply and exhaust lines 114, 116 and thermocouple leads 118. In an exemplary form, the distal end of the supply line 114 may be fluidly coupled to a fluid supply conduit, such as a supply hypotube 136, via a fluid tight seal using an adapter 134. For example, the adapter 134 may include a ribbed male proximal end that is received within the distal end of the supply line 114, while the female distal end of the adapter receives the supply hypotube 136. In an exemplary form, the connection between the supply adapter 134 and the supply line 114 can be supplemented using a crimp ring 138 that surrounds both the adapter and the supply hypotube to maintain a press fit between the adapter and the supply line. In addition, the connection between the supply adapter 134 and the supply hypotube 136 can be fluid-tight and is achieved using a fusion welding or brazing process to place the hypotube within the adapter. In this exemplary embodiment, the supply line 114 can be flexible or ductile and can be made of a single or multilayer structure of various metals and polymers, including but not limited to aluminum, copper, stainless steel, and thermoplastics (including extruded thermoplastics). As a further example, the supply line can include an inner layer for chemical compatibility (e.g., an extruded polymer tube) and one or more outer layers for strength (e.g., braided yarn and stainless steel), flexibility, wear resistance, and / or appearance. Moreover, the hypotube 136 and the supply adapter 134 can generally be more rigid than the supply line 114 and can be made of stainless steel and have a single or multilayer structure. As a further example, the hypotube 136 and the supply adapter 134 may be made of a single or multi-layer structure of various metals and polymers, including but not limited to aluminum, copper, stainless steel, and thermoplastics (including extruded thermoplastics). In addition, the hypotube 136 and the supply adapter 134 may include an inner layer for chemical compatibility (e.g., an extruded polymer tube) and one or more outer layers for strength (e.g., aluminum, stainless steel, braided wire), flexibility, wear resistance, and / or appearance.

[0054] In an exemplary form, the annular space between the exterior of the hypotube 136 and the interior of the ductile shaft 104 can form a fluid exhaust conduit 105 that can deliver the exhaust flow from the ablation tip 102 to the exhaust line 116. The distal end of the exhaust line 116 can be fluidly coupled to the exhaust adapter 140 via a fluid tight seal. Generally, in some exemplary embodiments, the exhaust adapter 140 can be operable to change the arrangement of the fluid exhaust conduit 105 and the fluid supply conduit 136 from a coaxial orientation to a parallel (non-coaxial) orientation. For example, the exhaust adapter 140 can include a ribbed convex proximal end 141 received within the distal end of the exhaust line 116, while the concave distal end 143 of the adapter receives the proximal end of the ductile shaft 104. Figure 4 An exemplary adapter 140 is shown having a substantially constant cross-sectional area for the flow of the exhaust stream between the inlet and outlet ends. However, it should be noted that the cross-sectional area available for the exhaust stream may vary between the inlet and outlet ends as a means of managing back pressure (see Fig. 20). In an exemplary form, the connection between the drain adapter 140 and the drain line 116 can be supplemented using a crimp ring 142 that surrounds both the adapter and the drain line 116 to maintain a press fit between the adapter and the drain line. In addition, the connection between the adapter 140 and the ductile shaft 104 can be fluid-tight and achieved using a brazing process to seat the shaft within the adapter so that the proximal end of the ductile shaft abuts a distal shoulder 145 of the adapter to form a seal therebetween. To help promote a continued fluid seal between the ductile shaft 104 and the adapter 140, the distal end of the adapter includes a frustoconical cone 144 that receives a frustoconical compression fitting 146 (e.g., a ferrule). The compression fitting 146 is repositioned proximally using a nut 148 that threadably engages helical threads 150 located around the periphery of the distal end of the adapter 140. In this manner, as the nut 148 is tightened, the nut pushes against the compression fitting 146, which causes the compression fitting to reduce its outer circumference and tightly clamp the exterior of the ductile shaft 104. Continued tightening of the nut 148 applies an even tighter clamping force between the compression fitting 146 and the exterior of the ductile shaft 104 to inhibit relative movement therebetween. A thread locking agent (not shown) may be applied between the threads of the nut 148 and the threads of the adapter 140 to inhibit relative movement between the nut and the adapter, thereby working together to maintain the relative position of the ductile shaft 104 against the distal shoulder 145 of the adapter 140 in a fluid-tight seal. In an exemplary form, the adapter 140 includes a passageway that accommodates the throughput of the hypotube 136, such that the distal end of the adapter is aligned with the hypotube and the ductile shaft 104 in a concentric arrangement. In the exemplary embodiment, the drain line 116 can be flexible or ductile and can be made of a single layer or multilayer structure of various metals and polymers, including but not limited to aluminum, copper, stainless steel, and thermoplastics (including extruded thermoplastics). As a further example, the drain line can include an inner layer for chemical compatibility (e.g., an extruded polymer tube) and one or more outer layers for strength (e.g., braided yarn and stainless steel), flexibility, wear resistance, and / or appearance. And the ductile shaft 104 and adapter 140 can generally be more rigid than the drain line 116 and can be made of stainless steel and have a single layer or multilayer structure. As a further example, the ductile shaft 104 and adapter 140 can be made of a single layer or multilayer structure of various metals and polymers, including but not limited to aluminum, copper, stainless steel, and thermoplastics (including extruded thermoplastics). Additionally, the ductile shaft 104 and adapter 140 may include an inner layer for chemical compatibility (eg, extruded polymer tubing) and one or more outer layers for strength (eg, copper, aluminum, stainless steel, braided yarn), flexibility, wear resistance, and / or appearance.

[0055] refer to Figure 6, the distal end of the handle housing 108 defines a distal opening 138 through which the hypotube 136, the ductile shaft 104, the thermocouple leads 118, and the thermal insulator 106 can extend. As a further example, the hypotube 136 can be concentrically located within the ductile shaft 104, while the thermocouple leads 118 extend along the exterior of the ductile shaft. Additionally, the thermal insulator 106 can be press-fit onto the ductile shaft 104 and the thermocouple leads 118.

[0056] like Figure 7 As shown, the longitudinal cross-section reflects the configuration within the insulated tube 106 and distal to the terminal end of the insulated tube. One or more thermocouples 160 may be positioned along the length of the ductile shaft 104 and electrically connected to the thermocouple lead 118 to provide temperature measurement. In an exemplary form, the thermocouple 160 may be brazed to the outside of the ductile shaft 104, but covered by the insulated tube 106. As a further example, the thermocouple 160 may be partially embedded in the ductile shaft 104 and may be operable to provide temperature measurement specific to a fluid flow (exhaust or supply) flowing within the ductile shaft. As a further example, the thermocouple 160 may be offset from the distal end of the insulated tube by approximately one-half to three inches (including 1.34 inches), and other thermocouples may be arranged along the length of the insulated tube.

[0057] Continue to refer Figure 7 and Figure 8-12, for example, the ductile shaft 104 may surround a hypotube 136, which is surrounded by the insulated tube 106. Near the distal end of the insulated tube 106, the insulated tube 106 may be hollowed out to provide a circumferential gap between the insulated tube and the ductile shaft 104. In the exemplary embodiment, the gap may be sized to receive a more flexible insulated conduit 170, wherein the longitudinal length of the gap may vary from approximately 0.1 inches to more than 1.0 inches (including 0.32 inches). For example, the insulated conduit 170 may include a spacer 174 inserted between the flexible cover 176 and the ductile shaft 104, which may maintain an insulating gap (e.g., an air gap) between the flexible cover and the ductile shaft. In an exemplary form, the spacer 174 may include one or more (e.g., four) spirals 174a, 174b, 174c, and 174d (having a substantially constant circular axial cross-section and / or a common axial dimension) that are longitudinally offset such that at any given axial cross-section along the longitudinal length, the corresponding spirals may be oriented at 12 o'clock, 3 o'clock, 6 o'clock, and 9 o'clock, respectively. At each longitudinal end, the spirals 174a, 174b, 174c, 174d may be coupled together or interfaced with a static structure to maintain the position of the segment ends. For example, each spiral may include a variety of non-conductive materials, such as, but not limited to, polymers, such as thermoplastics. In some exemplary embodiments, the individual spirals 174a, 174b, 174c, 174d may be formed as hollow tubes, which may optionally contain insulating materials. At the proximal end 175 of the insulated conduit 170, the outer diameter may be reduced or necked 173 to allow the proximal end to be inserted into the gap between the ductile shaft 104 and the distal end of the insulated tube 106. For example, the insulated catheter 170 may be necked to have an outer major dimension that is less than the outer diameter of the spirals 174a, 174b, 174c, 174d. Moving distally, the outer diameter of the insulated catheter 170 may increase and include a proximal shoulder 180 against which the proximal end of the spacer 174 rests. For example, the insulated catheter may include any insulating material having any number of configurations to provide a vacuum or fluid gap (e.g., a stagnant fluid pocket), such as, but not limited to, polystyrene foam. The insulated catheter 170 may be operable to thermally insulate the extendable shaft 104 from the external environment. In this exemplary embodiment, the extendable shaft 104, the hypotube 136, and the insulated catheter 170 may be sufficiently flexible to allow bending in excess of 180 degrees to reposition the ablation tip 102 between a starting position and an end position (see Fig.12 ).

[0058] Steering Fig.13 and 14, an alternative exemplary embodiment may replace the aforementioned insulating conduit 170 with an alternative exemplary flexible cover 190 for surrounding the ductile shaft 104 and the hypotube 136. In an exemplary form, the flexible cover 190 may include a plurality of internal protrusions 192 extending from the interior of a circumferentially continuous cover 194, wherein the protrusions may be arranged in an alternating circular and axial pattern along the longitudinal length. The arrangement of the protrusions defines an air gap (e.g., a non-flowing fluid pocket) 193 between the ductile shaft 104 and the continuous cover 194, which results in thermal insulation regardless of whether the ductile shaft 104 is oriented linearly or is specifically implemented as an arcuate shape indicating some kind of curvature (see Fig.12 ). Using the arrangement of the protrusions 192, a larger volume of air space can be created compared to the previously described insulated conduit 170. In addition, by forming the protrusions 192 into a conical, frustoconical, or hemispherical shape, the contact surface area between the protrusions and the ductile shaft 104 for conductive heat transfer can be reduced. Those skilled in the art will appreciate that the shape and pattern of the protrusions can be modified to improve the thermal insulation performance.

[0059] refer to Figure 15-17 , the distal end 196 of the flexible, insulated catheter 170 can present a reduced or necked outer diameter 197 (as can the flexible covering 190 if used instead). For example, the insulated catheter 170 can be necked to have an outer major dimension that is less than the outer diameter of the spirals 174a, 174b, 174c, 174d. As part of the reduced outer diameter of the insulated catheter 170, a distal shoulder 184 can be formed internally, and the distal end of the spacer 174 can be seated on the distal shoulder 184. Inserted proximally from the distal end 196 of the insulated catheter 170, the expandable shaft 104 can terminate and be connected to the ablation tip 102 in a fluid-tight manner. For example, as Fig.16 As depicted, a fluid tight seal may be achieved via a weld 198 at the connection location between the ablation tip 102 and the ductile shaft 104, such as, but not limited to, a circumferential surface weld and a circumferential butt weld. Fig.17 As depicted, the ductile shaft 104 may extend into a cavity formed into the ablation tip 102, and a fluid tight seal may be achieved by a weld 198 at the lap joint, such as, but not limited to, a circumferential fillet weld. Those skilled in the art will fully appreciate that other forms of fluid connection of the ductile shaft 104 and the ablation tip 102 are contemplated herein and include, but are not limited to, chemical bonding (e.g., adhesives), brazing, welding (e.g., spin and friction welding), swaging, and mechanical connection (e.g., threaded connection, friction fit, etc.).

[0060] Return to Fig.15In an exemplary form, the ablation tip 102 terminates at a closed distal end 103 and includes a solid metal housing having an internal cavity 200 configured to receive a terminal end 202 of a hypotube 136 extending beyond the ductile shaft 104. In this exemplary embodiment, the metal forming the ablation tip 102 may include any metal or metal alloy that can be used in a surgical setting, including but not limited to aluminum, titanium, stainless steel, copper, silver, gold, and any other thermally conductive metal or alloy, including coatings comprising one or more of the foregoing materials. For example, the cavity 200 may be embodied as a cylindrical shape that tapers conically toward a distal point 204. In this exemplary embodiment, the distal terminal end of the hypotube 136 includes a nozzle 206 through which a cryogenic fluid can be discharged and flow into the portion of the cavity 200 not occupied by the hypotube. In exemplary forms, the nozzle 206 may have a nozzle opening having a diameter between 0.05 and 0.001 inches and be positioned at the distal end of the cavity 200 anywhere from 0.005 inches to 2.0 inches (including 0.100 inches). Although not required, the hypotube 136 may also include a fluid flow feature 208, such as upstream of the nozzle 206 (e.g., between the hypotube 136 and the nozzle 206), to change the cross-sectional area available for cryogenic fluid to flow through the nozzle 206. For example, the hypotube 136 may be coupled to a fluid flow feature (e.g., a fluid flow constriction) 208, which is operable to reduce the cross-sectional area available for cryogenic fluid flow proximate the nozzle 206, which is operable to increase the pressure of the cryogenic fluid at the nozzle compared to the pressure of the cryogenic fluid flowing upstream of the fluid flow feature. Generally, the nozzle 206 and / or the fluid flow feature 208 may have a cross-section that is substantially smaller than the cross-section of the fluid supply conduit (e.g., the hypotube 36) upstream of the terminal end of the fluid supply conduit. The nozzle may have a cross-section for fluid flow that is substantially smaller than a cross-section for fluid flow of the fluid flow feature 208 .

[0061] In this exemplary embodiment, it is contemplated that the cryogenic fluid exiting the nozzle 206 is at a higher pressure upstream of the nozzle and is allowed to expand at a significantly lower pressure downstream of the nozzle within the cavity 200, thereby producing a Joule-Thompson expansion and significantly reducing the temperature of the cryogenic fluid and the ablation tip 102. By way of example, the cryogenic fluid may include any number of cryogenic fluids, such as, but not limited to, nitrous oxide, argon, carbon dioxide, and phase change fluids. As a further example, in the case of nitrous oxide, the cryogenic fluid may be supplied as a liquid at a temperature of 26.7° C. and a pressure of 800 psi upstream of the nozzle, and may include a gas phase or a gas-liquid mixed phase at approximately 45 psi and -68° C. within the ablation tip cavity 200. By the low pressure cryogenic fluid flowing through the cavity 200 and around the hypotube 136 and continuing into and through the ductile shaft 104 to surround the hypotube, a countercurrent flow may be established, thereby providing pre-cooling for the cryogenic fluid flowing through the hypotube as the Joule-Thompson expansion within the ablation tip 102 continues. Although not required, a vacuum or low pressure purge may be applied to the exhaust line 116 (see Figure 1 ) to accelerate the flow of the expanding cryogenic fluid through the ductile shaft 104, through the exhaust adapter 140, and into the exhaust line. As the Joule-Thompson expansion continues to occur at the ablation tip 102, the exterior of the tip 102 becomes cool enough to be used in an ablation procedure by contacting the tip with the tissue to be ablated. For example, an exemplary flow rate of the cryogenic fluid through the nozzle 206 ranges from approximately 15 to greater than 100 cubic centimeters per minute, depending on the cryogenic fluid utilized.

[0062] refer to Figure 15-19 In this exemplary embodiment, the ablation tip 102 may be embodied as a spherical outer surface 107, such as a hemispherical surface having a diameter ranging from approximately 3.0 mm to 18.0 mm. Generally, as used herein, "spherical" may refer to an enlarged (relative to adjacent structures) and generally rounded outer surface. The ablation tip 102 may utilize other outer shapes and surfaces, such as but not limited to Fig.18 The domed cylindrical surface depicted in Fig.19, or any other various spherical surfaces known to those skilled in the art. For outer surfaces other than spherical, the major axial dimension may be between 1.0 and 25 millimeters. As a further example, the ablation tip 102 may be specifically embodied as any spherical outer surface. Those skilled in the art will appreciate that the outer surface of the ablation tip 102 may be conformable to any number of external shapes specifically designed to perform specific ablations of specific anatomical features. In an exemplary form, the ablation tip 102 may be necked to include a proximal outer surface having a substantially constant axial profile, the diameter of which is smaller than the diameter of the spherical outer portion. The necked section may terminate at a step change in the axial diameter to facilitate a fluid-tight seal between the ablation tip 102 and the extendable shaft 104. In addition, the ablation tip 102 may be attached to or detached from the extendable shaft 104 using methods known in the art. Typically, in some exemplary embodiments, the spherical distal outer surface 107 of the distal ablation segment 101 may extend a longitudinal length L B , the longitudinal length L B The longitudinal length L of the exposed outer surface of the distal ablation zone may be AS In other exemplary embodiments, the longitudinal length L of the spherical outer surface 107 of the distal ablation zone 101 is B may extend less than the longitudinal length L of the exposed outer surface of the distal ablation zone AS half.

[0063] refer to Fig. 20 , an alternative exemplary adapter 240 including a flow restriction element may be used in place of the aforementioned exemplary adapter 140 to throttle the exhaust flow of refrigerant from the extendable shaft 104, thereby generating back pressure. In an exemplary form, the temperature that can be achieved by the ablation tip 102 may be proportional to the back pressure of the exhaust flow of the refrigerant, because a greater back pressure of the refrigerant results in a higher temperature at the ablation tip. In an exemplary form, most of the heat removal may be the result of a phase change (boiling) of the refrigerant within or near the ablation tip 102. The temperature that can be achieved by the ablation tip 102 is proportional to the boiling temperature (vaporization temperature) of the refrigerant, which is proportional to the pressure of the refrigerant. For example, as the back pressure of the refrigerant increases, the temperature also increases, reaching the lowest possible temperature that the ablation tip can achieve. Without some kind of flow restriction element (e.g., a valve or throttle) to delay the flow of the exhaust flow of the refrigerant, back pressure may become a byproduct of inconsistent flow restrictions in the exhaust path, because these flow restrictions may be flow rate dependent. Fig. 20An exemplary flow restriction element in the form of a constriction 242 is depicted between the exhaust refrigerant flow from the expandable shaft 104 and ultimately into the exhaust line 116. Assuming that the size of the constriction 242 is a fixed size and there is no valve, the amount of back pressure generated is a function of the flow rate, where higher flow rates result in greater back pressure. In some exemplary embodiments according to at least some aspects of the present disclosure, the adapter 140 may be configured such that the constriction 242 has a cross-sectional area for the exhaust refrigerant flow that is a fraction of the cross-sectional area of ​​the exhaust refrigerant flow of the exhaust line 116. In an exemplary embodiment, the cross-sectional area of ​​the constriction 242 for the exhaust refrigerant flow may be less than about 70% of the cross-sectional area of ​​the exhaust refrigerant flow of the exhaust line 116. In another exemplary embodiment, the cross-sectional area of ​​the constriction 242 for the exhaust refrigerant flow may be less than about 50% of the cross-sectional area of ​​the exhaust refrigerant flow of the exhaust line 116. In yet another exemplary embodiment, the cross-sectional area of ​​the contraction 242 for the refrigerant discharge flow may be less than about 30% of the cross-sectional area of ​​the discharge line 116 for the refrigerant discharge flow. In yet another exemplary embodiment, the cross-sectional area of ​​the contraction 242 for the refrigerant discharge flow may be less than about 15% of the cross-sectional area of ​​the discharge line 116 for the refrigerant discharge flow. In another exemplary embodiment, the cross-sectional area of ​​the contraction 242 for the refrigerant discharge flow may be about 10% of the cross-sectional area of ​​the discharge line 116 for the refrigerant discharge flow.

[0064] refer to Fig.21, the second exemplary cryoprobe (cryoprobe) 300 may share many of the same components as the first exemplary cryoprobe 100, including the handle housing 108, the connection bundle 112, the supply line 114, the exhaust line 116, the thermocouple leads 118, and the insulated tube 106. However, the second exemplary cryoprobe 300 differs in the configuration of the extendable shaft and the ablation tip. In the exemplary embodiment, the extendable shaft 304 may or may not cover the flexible insulated conduit 170. Regardless of whether a flexible insulated conduit is utilized, the extendable shaft 304 may surround a fluid exhaust conduit 310 to define a path for directing spent refrigerant to the handle housing 108. The outer circumference of the exhaust conduit 310 cooperates with the inner circumference of the extendable shaft 304 to define a fluid supply conduit 312 for cryogenic fluid. In exemplary forms, the ratio of the cross-sectional area of ​​the exhaust conduit 310 to the supply conduit 312 may range between approximately 30:1 and 1:1. A significant difference from the present exemplary cryoprobe conduit is that the exhaust conduit 310 is circumferentially inset from the supply conduit 312 as a means of avoiding inadvertent ablation of tissue that may be in contact with the extendable shaft 304 (assuming that the condition of the cryofluid traveling through the supply conduit is not necessarily cold enough to ablate tissue (e.g., above about -10°C)). In the exemplary form, the supply conduit 312 does not become cold enough to ablate tissue because the fluid flowing therethrough is at a high pressure (e.g., 300 to 800 psi) and therefore the boiling point of the cryofluid is above the tissue ablation temperature. The heat generated by compressing the cryofluid also helps to keep the exterior of the supply conduit 312 above the tissue ablation temperature. In addition, any heat exchange from the exhaust tube to the cryofluid flowing through the supply conduit 312 will be forced through the boiler 320 into the exhaust stream. The distal end of the extendable shaft 304 extends further than the distal end of the exhaust conduit 310. This difference in the distal terminus provides a recess of the collar to partially receive a boiler 320 having an axial cross-section that matches the axial cross-section of the ductile shaft 304, which in exemplary forms may be circular.

[0065] refer to Fig.21 and 22, the proximal end of the boiler 320 may include a nipple 324 configured to be received within the exhaust conduit 310 to form a fluid seal between a central bore 328 extending through the boiler 320 and the interior of the exhaust conduit 310. In a further exemplary form, the nipple 324 may include an externally raised circumferential ring 329 configured to form a friction fit and fluid seal between the nipple 324 and the exhaust conduit 310 to maintain the relative longitudinal position of the boiler 320 relative to the exhaust conduit 310. To prevent over-insertion of the boiler 320 into the exhaust conduit 310, the nipple 324 includes a circumferential lip 330 against which the distal end of the exhaust conduit 310 may abut. In an exemplary form, the nipple 324 may terminate distally in a proximal flange 332 configured to extend axially to fill an internal gap formed by the overhanging distal end of the ductile shaft 304. Despite filling the internal gap, the boiler 320 may be provided with one or more channels 334 that provide fluid communication between the supply conduit 312 and the interior of the distal ablation section 302, which may include an ablation tip 336 and / or the boiler 320, the ablation tip 336 including a closed distal end 303. In an exemplary form, the boiler 320 may be made of a polymer material and injection molded over one or more pre-existing lines (such as a hypotube 335) to define the channel 334 and allow fluid communication therethrough. For example, the channel 334 may not extend substantially beyond the distal end of the body of the boiler 320, thereby forming a nozzle that is substantially flush with the body of the boiler 320. Alternatively, the hypotube 335 may extend substantially beyond the distal end of the body of the boiler 320 in a spiral or other configuration to allow the refrigerant fluid expanding within the ablation tip 336 to pre-cool the refrigerant fluid before the refrigerant fluid exits the channel within the interior of the ablation tip (see Fig.23 ).

[0066] For example, to fluidly seal the ablation tip 336 and the supply conduit 312 around the boiler 320, the boiler 320 may include two or more outer circumferential grooves 340, each receiving a corresponding O-ring 342. Inserted into the grooves 340 on the outer circumference of the boiler 320 may be a raised rib 343 with a corresponding recessed groove 344. In this exemplary embodiment, the height of the raised rib 343 may be selected to be slightly less than the material thickness of at least one of the ductile shaft 304 and the ablation tip 336, so that when the boiler 320, the ductile shaft 304, and the ablation tip 336 are connected, the final outer surface of the connected components is not significantly uneven. To connect the boiler 320, the ductile shaft 304, and the ablation tip 336 to one another, the distal end of the ductile shaft 304 may be curled downwardly to position its end within the proximal recess of the recess 344, while the proximal end of the ablation tip 336 is similarly curled downwardly to be received within the distal recess of the recess 344. It should be noted that this curling action taken with respect to the ductile shaft 304 and the ablation tip 336 may also operate to complete the formation of a fluid tight seal via the O-ring 342.

[0067] The formation of a fluid tight seal allows the cryogen to flow out of the supply conduit 312, through the channel 334 of the boiler 320, and into the interior of the ablation tip 336. Upon reaching the ablation tip 336, the cryogen fluid is allowed to expand at a significantly lower pressure within the interior of the ablation tip 336, thereby producing a Joule-Thompson expansion and significantly reducing the temperature of the cryogenic fluid and the ablation tip. For example, the cryogenic fluid may include any number of cryogenic fluids, such as but not limited to nitrous oxide, argon, and carbon dioxide. As a further example, the cryogenic fluid may be a phase change fluid that is in equilibrium (or saturation point) at room temperature (approximately 15°C to 25°C) and a pressure of less than 2000 psi. As a further example, in the case of nitrous oxide, the cryogenic fluid may be supplied as a liquid upstream of the boiler 320 at a temperature of approximately 80°F and a pressure of approximately 800 psi, and may be discharged in a gas phase or a gas-liquid mixed phase at approximately 45 psi and -68°C. As the Joule-Thompson expansion continues to occur within the ablation tip 336, the exterior of the ablation tip becomes cool enough for the ablation procedure so that the ablation tip can come into contact with the tissue to be ablated. For example, an exemplary flow rate of the refrigerant fluid through the passage 334 ranges from approximately 15 to greater than 100 cubic centimeters per minute, depending on the refrigerant fluid utilized.

[0068] As previously discussed, the temperature that the ablation tip 336 can reach is directly proportional to the back pressure of the refrigerant exhaust flow. Therefore, the second exemplary cryoprobe 300 may (or may not) include a flow restriction element in the form of a pressure (e.g., pressure relief) valve 350 proximate the ablation tip 336 to maintain a predetermined back pressure within the ablation tip 336 by regulating the flow of spent refrigerant through the exhaust conduit 310. In an exemplary form, the pressure relief valve 350 may include a frustoconical plug 352 that is operably coupled to a spring 354 having a predetermined tension (i.e., spring stiffness). In this exemplary embodiment, the spring 354 may include a coil spring having an enlarged section 356 that is blocked from proximally passing a distal frustoconical end 358 of the central bore 328. The distal frustoconical end 358 may also be operable to provide a funnel function for the refrigerant fluid that exits the interior of the ablation tip 336 and moves within the central bore 328. The tension of spring 354 is preloaded (i.e., the spring is biased) to maintain the engagement between plug 352 and frustoconical proximal end 359 of central bore 328 (serving as a valve seat for the valve body) in a substantially fluid tight seal until a predetermined pressure is reached. When the fluid pressure within central bore 328 reaches the predetermined pressure, the pressure of the refrigerant exerts a force on plug 352 sufficient to overcome the spring bias of spring 354, thereby allowing separation between plug 352 and frustoconical proximal end 359 of central bore 328. As a further example, those skilled in the art will appreciate that spring 354 may be selected or manipulated to set the back pressure maintained within the interior of ablation tip 336. As a further example, spring 354 may be selected or manipulated to set the back pressure maintained within the interior of ablation tip 336 to between 15-100 psi (inclusive between 30-50 psi). In an exemplary form, for a central bore 328 having a diameter of 0.125 inches at its narrowest position, a spring force of 0.6 lbf would be operable to maintain a 50 psi back pressure within the ablation tip 336. While the exemplary pressure relief valve 350 has been described as extending into the boiler 320 and proximate to the ablation tip 336, one skilled in the art will appreciate that one or more pressure relief valves may be positioned proximate to the boiler and / or not proximate to the ablation tip 336.

[0069] Regardless of the presence or absence of the pressure relief valve 350, as the Joule-Thompson expansion within the ablation tip 336 continues, a counterflow is established by the expanding cryogenic fluid flowing through the central hole 328 and into the exhaust conduit 310, thereby providing pre-cooling for the cryogenic fluid flowing through the supply conduit 312 and the channel 334. The gap 321 between the radially outer surface at the distal end of the boiler 320 and the radially inner surface of the ablation tip 336 can act as a nozzle, similar to the nozzle 206 of the cryoprobe 100. Similarly, the channel 334 can act as a fluid flow constriction similar to the fluid flow feature 208 of the cryoprobe 100. In some example embodiments, the cross-section of the gap (nozzle) 321 can be substantially smaller than the cross-section of the supply conduit 312 upstream of the boiler 320. Similarly, in some exemplary embodiments, the cross-section of the channel 334 can be substantially smaller than the cross-section of the supply conduit 312 upstream of the boiler 320. In some example embodiments, the cross-section of the gap (nozzle) 321 can be smaller than the cross-section of the channel 334. Although not required, a discharge line 116 (see Figure 1 ) is vacuumed or low-pressure purged to accelerate the flow of the low-pressure cryogenic fluid through the exhaust line 310 and into the exhaust line.

[0070] In this exemplary embodiment, the ablation tip 336 can be embodied as an outer spherical shape with a diameter ranging from approximately 3.0 mm to 18.0 mm. However, the ablation tip 336 can utilize other outer shapes, such as but not limited to Fig.18 The domed cylindrical shape depicted and Fig.19 As a further example, the ablation tip 336 may be embodied as any spherical outer shape (e.g., Fig.15 Those skilled in the art will appreciate that the outer shape of the ablation tip 336 may be amenable to any number of outer shapes specifically designed to perform a specific ablation of a specific anatomical feature.

[0071] refer to Fig.24 and 25 , those skilled in the art will also appreciate that various configurations may be utilized within the extendable shaft 304 to deliver cryogenic fluid to the ablation tip 336 and to transport the expanded / cooled cryogenic fluid away from the ablation tip 336. For example, Fig.24, the ductile shaft 304 may house an insert 400 that defines an insulating bladder (e.g., a stagnant fluid bladder) 410, one or more cryogenic supply conduits 420, and one or more cryogenic exhaust conduits 430. The supply conduits 420 may be separate from the exhaust conduits 430. An exemplary insert 400 may include an extruded polymer such as, but not limited to, polypropylene, polyvinylidene fluoride, and low-density polyethylene. The insert 400 may be embodied as a triangular shape (e.g., in cross-section) to provide three contact points on the interior of the ductile shaft 304 and reduce those contact points between the insert and the ductile shaft, thereby reducing conductive heat transfer between the relatively cool exhaust conduits 430 and the surface of the ductile shaft 304. As a further example, the triangular shape may be selected to fit within the diameter of the ductile shaft 304 and provide three contact points between the insert and the shaft, recognizing that an equilateral triangle provides a minimum amount of dead air volume, while a right triangle provides a maximum amount of dead air volume. In some example embodiments, the dead air volume can be sealed and evacuated, which can provide a greater barrier to heat transfer to the outer surface. As an alternative to the triangular shape, additional sided shapes (e.g., shapes with four or more sides in cross section) can be used. In an exemplary form, the supply conduit 420 and the exhaust conduit 430 may include nothing other than the longitudinal channels formed in the insert 400, or may include special tubing (such as a hypotube) extruded around the insert. It is also within the scope of the exemplary insert 400 to include one or more conduits for routing thermocouple leads (not shown) or sensor leads (not shown) to provide real-time information about the temperature and / or pressure within one or more of the conduits 420, 430 and the balloon 410.

[0072] Fig.25Depicted is an additional exemplary insert 450 that may be positioned within the ductile shaft 304 and may define an insulating bladder (e.g., stagnant fluid bladder) 460, one or more cryogenic supply conduits 470, and one or more cryogenic exhaust conduits 480. The exemplary insert 450 may include an extruded polymer such as, but not limited to, polypropylene, polyvinylidene fluoride, and low-density polyethylene. The insert 450 may be embodied in a hexagonal shape to provide six contact points on the interior of the ductile shaft 304 and reduce those contact points between the insert and the ductile shaft, thereby reducing conductive heat transfer between the relatively cool exhaust conduits 480 and the surface of the ductile shaft. As a further example, by utilizing an object that has a pointed (low surface area contact) contact with the ductile shaft, the surface area for conductive heat transfer is reduced compared to an arcuate surface that matches the internal curvature of the ductile shaft. In an exemplary form, the supply conduit 470 and the exhaust conduit 480 may not include anything other than the longitudinal channels formed within the insert 450, or may include a dedicated tubing around which the insert is extruded. Also within the scope of the exemplary insert 450 is one or more conduits for routing thermocouple leads (not shown) or sensor leads (not shown) to provide real-time information regarding temperature and / or pressure within one or more of the conduits 470 , 480 and balloon 460 .

[0073] One or more components disclosed herein may include an echogenic coating to allow ultrasound visibility during surgical procedures where direct line of sight may be obstructed. Those skilled in the art will appreciate that ultrasound is used for non-line of sight surgical procedures, and therefore a detailed discussion of ultrasound is omitted for the sake of brevity. As an alternative to ultrasound, other visualization methods known in the art may be used.

[0074] The aforementioned cryoprobes 100, 300 may also include electrical sensing to indicate that the ablation sequence is complete. For example, one may pulse (i.e., send an electrical signal through) a nerve or other tissue distal to the ablation (such as in the intercostal space during a cryoanalgesia procedure) and attempt to measure the electrical signal at a location proximal to the ablation, which should dissipate the electrical signal or render it unmeasurable because the electrical signal is interrupted by the ablation. Continuous or discontinuous pulses may be used to discern when the ablation procedure is complete.

[0075] Go to Fig.26, an exemplary process 500 for using any of the aforementioned cryoprobes 100, 300 will be discussed below. As a prerequisite, a supply of cryogenic fluid needs to be established 502 from a static location or from a portable fluid holding container. For example, in an exemplary context of using nitrous oxide as a cryogenic fluid, a portable fluid holding container (e.g., a 20 pound tank) of liquefied nitrous oxide can be fluidly connected to an AtriCure Cryo Module (ACM) which is itself fluidly connected to the cryoprobe 100.

[0076] In an exemplary form, the ACM may be intended for cryosurgical treatment of arrhythmias. The ACM may include a non-sterile, reusable device cryoablation probe and / or a sterile, disposable device cryoablation probe. The ACM may also include an electromechanical cryosurgical unit (which may include controls, displays, indicators, and associated programming logic or circuits) that delivers a cryogenic fluid (nitrous oxide (N2O)) to the cryoablation probe under conditions to cool the active area of ​​the probe, which, when the cryogenic fluid flows through the probe, is operable to ablate tissue in contact with the active area, which in an exemplary form allows an operator to create an ablation line through tissue (such as, but not limited to, cardiac tissue). The ACM may also include a cryogenic fluid holding container, a cryogenic fluid supply line in fluid communication (or selective fluid communication) with the holding container and the cryoablation probe, a cryogenic fluid exhaust line in fluid communication with the cryoablation probe, a holding container heater, and a manual switch that allows control of the delivery of cryogenic fluid from the holding container and to the cryogenic probe and the cryogenic probe itself. In an exemplary form, the ACM provides controlled delivery of cryogenic fluid to the cryoprobe to allow tissue injury to be created below -40°C, with a typical operating range between -50°C and -70°C.

[0077] In operation 504, the refrigerant condition may be adjusted and / or verified. In an exemplary form, the portable fluid holding container may have a heating blanket covering the tank, which may be operable to add heat to the container to control the internal pressure, which may range between approximately 700 psi (~17°C) and 850 psi (~23°C) in an exemplary form. For example, the ACM may provide visual feedback about the pressure and temperature of the container, which is updated in real time. To the extent that heating is required to achieve the proper pressure, a green light may illuminate as part of the ACM to indicate that the refrigerant tank pressure is within a predetermined operating range.

[0078] In operation 506, the user may activate the ACM to deliver pressurized cryogenic fluid to the cryoprobe via the supply line. For example, the ACM may deliver pressurized cryogenic fluid at approximately 725 psi to the inlet connection of the cryoprobe so that the pressure of the cryogenic fluid is between 500 and 725 psi just before reaching the ablation tip.

[0079] In operation 508, refrigerant may be delivered to the cryoprobe 100, 300. When the cryogenic fluid is initially delivered into the ablation tip, the cryogenic fluid expands to approximately atmospheric pressure (14.7 psi). In operation 510, the back pressure of the spent refrigerant may be monitored and / or adjusted. In an exemplary form, as more cryogenic fluid enters the ablation tip and the spent cryogenic fluid accumulates, back pressure begins to build and may be adjusted to reach a steady-state back pressure of approximately 52 psi, which corresponds to an ablation tip temperature of approximately -65°C. However, it should be noted that ablation of tissue using the ablation tip may begin after the temperature of the ablation tip reaches a predetermined value, which may be higher than the steady-state temperature, including but not limited to -40°C.

[0080] In operation 512, an ablation cycle may be initiated. When the ablation tip reaches the predetermined ablation temperature, the ACM may perform an ablation cycle in which the ablation tip is maintained at or below the predetermined ablation temperature for a predetermined time, such as but not limited to 120 seconds.

[0081] In operation 514, a defrost (e.g., warming) cycle may be recommended. In an exemplary form, after the ablation cycle is completed, the ACM may activate the defrost cycle. For example, the defrost cycle may include stopping the flow of discharged cryogenic fluid from the cryoprobe while continuing to supply the cryoprobe with cryogenic fluid. Ultimately, the cryogenic fluids within the probe are all at the same pressure and temperature, such as, but not limited to, approximately 800 psi (corresponding to an ablation tip temperature of approximately 10°C). It is noteworthy that various exemplary cryoprobes according to at least some aspects of the present disclosure may be configured to withstand pressures expected during a defrost cycle, which may be higher than the pressures expected during a freezing cycle. The ACM uses a thermocouple to monitor the temperature at the ablation tip and, when a predetermined defrost temperature is reached, stops the flow of cryogenic fluid to the inlet of the cryoprobe while allowing ventilation of the discharged cryogenic fluid, thereby ultimately raising the temperature of the cryoprobe and reducing the pressure to atmospheric conditions.

[0082] After the defrost cycle is terminated, the ACM may be reactivated (operation 506) to restart the freeze and defrost cycle. Alternatively, a program termination sequence may be initiated (operation 516) wherein the connection between the cryoprobe and the tank is interrupted and the ACM is deactivated.

[0083] refer to Fig.28, exemplary cryoprobes 100, 300 can also be used in cryoanalgesia applications. Cryoanalgesia or freezing of nerves 700 uses extreme cold to ablate peripheral nerves and produces a temporary but completely recoverable loss of sensory nerve function. Cryoanalgesia causes axonal rupture (according to Seddon's classification, this is a level of nerve damage), in which axons 702 and myelin sheaths are destroyed, but at least some surrounding tubular structures (such as endoneurium 704, perineurium 706, fiber bundles 710 and / or perineurium 708) remain intact. Subsequent Wallerian degeneration, i.e., a process in which the entire length of the distal nerve segment of the cryoanalgesia site (cryoinjury) is removed, takes approximately 1 week. Regeneration of the nerve begins from the proximal segment and continues at an average rate of 1-3 mm / day, following the intact structural components until the tissue is re-innervated. This process can take several weeks to several months, depending on how much the cryoinjury affects the tissue. Because cryoanalgesia maintains the structure of the nerve, it is not related to the development of neuromas.

[0084] Local analgesia for nerves (e.g., intercostal nerves) is intended for management of pain due to incisions, any surgical muscle ruptures, discomfort from nerve compression caused by surgical devices (e.g., retractors) and surgical fixators (e.g., sutures), and any openings created by tube or trocar sites. In an exemplary form, an exemplary procedure includes cryoanalgesia for post-thoracotomy pain, which includes cryoablation of the intercostal nerves. Attempting cryoablation at insufficiently cold temperatures (e.g., temperatures above -20°C) will only produce a transient nerve conduction block, where sensation is restored when the tissue thaws, while temperatures that are too cold (e.g., below -100°C) can induce permanent nerve damage. When placed against tissue (such as the pleura or intercostal nerves), an ice ball can form around the tip of the cryoprobe 100, 300, and heat extraction can penetrate the tissue by several millimeters to produce cryoinjury. In addition to the probe temperature, the extent of the cryoinjury can depend on many other factors, including the size and material of the cryoprobe, the duration of freezing, the rate of freezing, the rate of thawing, and the number of freeze-thaw cycles. Below is an exemplary procedure for cryoanalgesia in response to open-chest surgery that is effective for pain management and can be applied to any nerve in the animal's body.

[0085] refer to Fig. 27 , it is recommended that the cryoablation procedure be performed as early as possible in the procedure, such as before or immediately after thoracotomy. The target nerve, such as an intercostal nerve 602, may be located in the incised intercostal space 604 (e.g., between ribs 606, 608), preferably at the edge of the innermost intercostal muscle 610 and the membranous portion 612 of the internal intercostal muscle. A location close to the lateral cutaneous branch but at least 2 cm from the ganglion 614 and at least 4 cm from the spine may be selected.

[0086] The cryoprobe 100, 300 (including the ablation tip 102) can be exposed approximately 2-3 cm, where the elongated shaft can be shaped with a curve for the costal groove. A hockey stick shape or a C shape can be used. The ablation tip 102 of the cryoprobe 100, 300 can be placed directly on top of the nerve 602 at a slight angle to ensure that the nerve is directly below the ablation tip. The insulated tube of the cryoprobe 100, 300 can be positioned over the ribs 606, 608 and carefully slid down the ribs until the cryoprobe falls off the ribs into the costal groove.

[0087] Prior to ablation, the ablation tip 102 may be pressed into the rib groove with sufficient pressure to produce compression of the tissue, thereby achieving stability and reducing local perfusion. If pressed against the skin, sufficient pressure may be sufficient pressure to produce blanching. After positioning the ablation tip 102 to contact the nerve 602 or in close proximity to the nerve 602, the cryogenic fluid flowing through the cryogenic probe 100, 300 may be operated to cool the ablation tip (to approximately -65C) and start or continue the freezing duration to freeze the nerve. For example, if the freezing probe tip 102 is positioned close to the nerve 602, the freezing duration may be 120 seconds, while the freezing duration may be shorter (e.g., 90 seconds) when the ablation tip is in direct contact with the nerve. The freezing probe 100, 300 may be defrosted after the freezing duration to allow detachment between the ablation tip and the animal tissue. In an exemplary form, as the freezing probe 100, 300 is defrosted, the ablation tip 102 may become bright and shiny and may be moved without resistance. To prevent tissue or nerve damage, the cryoprobe should not be forcibly moved while adhered to tissue. After defrosting, the cryo-duration process and defrost sequence can be repeated at another location on the same nerve (or a different location on a different nerve) and repeated as needed to achieve an appropriate pain management outcome. In general, some of the exemplary cryoanalgesia procedures described above can be repeated on intercostal nerves located in each of the third to ninth intercostal spaces.

[0088] In the cardiac space, it may be difficult to place an ablation tip from a conventional cryoprobe known in the art. Ablation of nerves in the thoracic space may be easily accomplished by providing better contact on the nerves using the exemplary ablation tip 102. In addition, due to the size of the tip, less ablation may be required.

[0089] From the above description, it will be apparent to one of ordinary skill in the art that, while the methods and apparatus described herein constitute exemplary embodiments of the present invention, the invention described herein is not limited to any precise embodiment, and changes may be made to these embodiments without departing from the scope of the present disclosure as defined by the claims. In addition, it should be understood that the present disclosure is defined by the claims, and that any limitation or element describing the exemplary embodiments set forth herein is not intended to be incorporated into the interpretation of any claim element unless such limitation or element is explicitly stated. Likewise, it should be understood that it is not necessary to satisfy any or all of the identified advantages or purposes of the present disclosure disclosed herein in order to fall within the scope of any claim, because the present disclosure is defined by the claims, and because inherent and / or unforeseeable advantages of the present disclosure may exist even though they may not be explicitly discussed herein.

Claims

1. A cryogenic probe, comprising: an elongated shaft at least partially housing or defining the fluid supply conduit and the fluid exhaust conduit, the elongated shaft including a distal ablation section terminating at a closed distal end; a housing at least partially surrounding at least a portion of the proximal end of the elongated shaft and receiving or defining at least a portion of the fluid supply conduit and a portion of the fluid exhaust conduit; as well as a boiler including a passage providing fluid communication between the fluid supply conduit and an interior of the distal ablation section; A valve is within the elongated shaft downstream of the distal ablation section, the valve being in fluid communication with the fluid exhaust conduit and regulating fluid flow from the distal ablation section and through at least a portion of the fluid exhaust conduit.

2. The cryogenic probe according to claim 1, wherein: The valve is interposed between the fluid discharge conduit and a discharge inlet of the boiler.

3. The cryogenic probe according to claim 1, wherein: The boiler includes a plurality of one or more channels.

4. The cryogenic probe according to claim 1, wherein: The valve includes a valve plug configured to engage a valve seat of the boiler and form a seal therebetween.

5. The cryogenic probe according to claim 4, wherein: The valve plug is biased to engage the valve seat.

6. The cryogenic probe according to claim 4, wherein: The valve plug is biased by a spring to engage the valve seat, and at least a portion of the spring is located within the distal ablation section.

7. A cryogenic probe according to any preceding claim, wherein: The distal ablation zone includes a spherical outer surface.

8. The cryogenic probe according to claim 7, wherein: The spherical outer surface includes a hemispherical portion.

9. A cryogenic probe according to any preceding claim, wherein: The distal ablation zone includes a necked zone to change a cross-section of the distal ablation zone.

10. A cryogenic probe according to any preceding claim, wherein At least a portion of the fluid supply conduit extends into the distal ablation zone.

11. The cryogenic probe according to claim 10, wherein: At least the portion of the fluid supply conduit extending into the distal ablation zone includes a fluid flow constriction prior to reaching a nozzle within the distal ablation zone.

12. A cryogenic probe according to any preceding claim, wherein The proximal aspect of the distal ablation section is fluidly sealed to the distal aspect of the elongated shaft using at least one of an adhesive bond and a fusion weld.

13. A cryogenic probe according to any preceding claim, further comprising a flexible, thermally insulated conduit surrounding the elongate shaft along at least a portion of its longitudinal length.

14. The cryogenic probe according to claim 13, wherein: The flexible, thermally insulated conduit surrounds the elongated shaft along a majority of its longitudinal length.

15. The cryogenic probe according to claim 13, wherein: The flexible, thermally insulated conduit includes a spacer interposed between an outer covering of the flexible, thermally insulated conduit and an exterior of the elongated shaft.

16. The cryogenic probe according to claim 15, wherein: The spacer comprises foam.

17. The cryogenic probe according to claim 15, wherein: The spacer comprises a spiral.

18. The cryogenic probe according to claim 15, wherein: The spacer includes a plurality of polymer helices.

19. The cryogenic probe according to claim 18, wherein: The polymer spirals are longitudinally offset from one another along the flexible, thermally insulated conduit; and, Each polymer helix has a common axial dimension.

20. The cryogenic probe according to any one of claims 15 to 19, wherein: The spacer terminates prior to reaching at least one of the proximal end and the distal end of the flexible, thermally insulated conduit.

21. The cryogenic probe according to claim 17, wherein: The flexible, thermally insulated conduit is necked to have an outer major dimension at at least one of a proximal end and a distal end of the flexible, thermally insulated conduit that is smaller than the helical outer diameter.

22. A cryogenic probe according to any preceding claim, wherein The elongated shaft provides for greater than 180 degrees of bending without breaking.

23. A cryogenic probe according to any preceding claim, wherein The interior of the elongated shaft and the exterior of the fluid supply conduit define the fluid exhaust conduit.

24. A cryogenic probe according to any preceding claim, wherein The interior of the elongated shaft and the exterior of the fluid exhaust conduit define the fluid supply conduit.

25. The cryogenic probe according to claim 7, wherein: The bulbous outer surface extends longitudinally over more than half of the longitudinal length of the exposed outer surface of the distal ablation section.

26. The cryogenic probe according to claim 7, wherein: The bulbous outer surface extends longitudinally less than half of a longitudinal length of an exposed outer surface of the distal ablation section.

27. The cryogenic probe according to claim 7, wherein: The distal ablation zone is configured to withstand pressure during a warming operation, the warming operation including preventing fluid from flowing through the fluid exhaust conduit.

28. A cryogenic probe according to any preceding claim, wherein The housing includes an interior cavity that receives an adapter operable to change the coaxial orientation of the fluid supply conduit and the fluid exhaust conduit to a parallel orientation.

29. The cryogenic probe of claim 1, said elongated shaft comprising at least one stagnant fluid bladder interposed between an exterior of said shaft and at least one of said fluid supply conduit and said fluid exhaust conduit.

30. The cryogenic probe of claim 29, the stagnant fluid pocket being at least partially defined by a spacer spiral.

31. The cryogenic probe according to claim 30, wherein The spacer spiral includes a plurality of spacer spirals.

32. The cryogenic probe according to claim 31, wherein The plurality of spacer spirals are longitudinally offset from one another along the length of the catheter.

33. The cryogenic probe of claim 30, wherein: The spacer spiral comprises an insulating material.

34. The cryogenic probe of claim 29, wherein: The at least one pocket of stagnant fluid is at least partially defined by an insert that also provides a passage for at least one of the fluid supply conduit and the fluid exhaust conduit.

35. The cryogenic probe of claim 34, wherein: The insert comprises a triangular cross-section and includes separate passages for the fluid supply conduit and the fluid exhaust conduit.

36. The cryogenic probe of claim 35, wherein: The separate passages for the fluid supply conduit and the fluid exhaust conduit include at least one of a plurality of fluid supply conduits and a plurality of fluid exhaust conduits.

37. The cryogenic probe of claim 34, wherein: The insert comprises a geometric cross-section having four or more sides and comprises separate conduits for the fluid supply conduit and the fluid exhaust conduit.

38. The cryogenic probe of claim 37, wherein: The separate conduits for the fluid supply conduit and the fluid exhaust conduit include at least one of a plurality of fluid supply conduits and a plurality of fluid exhaust conduits.

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