Cryosurgical probe with enhanced thermal performance

Abstract

The present disclosure relates to a cryosurgical probe having enhanced thermal performance. A probe and a method of using the probe. The probe may include a first member, a tip, a second member, and a third member. The first member may have a first end portion and a second end portion. The tip may be configured to engage the first member at the second end portion. The second member may be configured to extend and be positioned within the first member. The third member may be configured to be disposed at least partially outside the second member along at least a portion of the second member, engage an inner surface of the first member, and define at least one passageway between the third member and the first member. The probe may be coupled to a fluid supply device and a return device, and fluid may flow within the probe, including within the passageway defined between the first member and the third member.

Description

Technical Field

[0001] The present disclosure generally relates to medical devices, and more particularly, to cryosurgical probes and methods of using the same. Background Art

[0002] Cryosurgical probes are instruments used in medical procedures. Cryoablation is one such medical procedure. During cryoablation, an extremely cold fluid (liquid, gas, mixture, or other phase) can flow through a probe in thermal contact with the target tissue. Heat from the tissue is transferred from the tissue through the probe into the fluid, and the fluid carries the heat away from the target tissue. Removing the heat causes the tissue to freeze, thereby destroying the target tissue. The thermal performance of the probe depends on its rate of removing heat from the tissue. Summary of the Invention

[0003] The embodiments described herein relate to cryosurgical probes having improved thermal performance compared to existing designs. The improved performance of the embodiments described herein can enable shorter times to cool and freeze tissue, freeze larger volumes of tissue, or both. The improved thermal performance also results in less fluid being used for a given procedure, thereby both saving costs and reducing the outlet mass flow rate of the fluid.

[0004] According to some embodiments, a probe and a method of using the probe are disclosed. The probe can include a first member, a tip, a second member, and a third member. The first member can have a first end portion and a second end portion. The tip can be configured to engage the first member at the second end portion. The second member can be configured to extend and be positioned within the first member. The third member can be configured to be disposed at least partially outside the second member along at least a portion of the second member, engage an inner surface of the first member, and define at least one passageway between the third member and the first member. The probe can be coupled to a fluid supply device and a return device, and fluid can flow within the probe, including within the passageway defined between the first member and the third member. Brief Description of the Drawings

[0005] The features and advantages of the present disclosure will be more fully disclosed or will become apparent in the following detailed description of example embodiments. The following detailed description of the example embodiments will be considered in conjunction with the accompanying drawings, where like reference numerals refer to like components, and where:

[0006] Figure 1 is a perspective view of a probe according to some embodiments;

[0007] Figure 2 is a perspective cross-sectional view of an end of a probe according to some embodiments;

[0008] Figure 3A is a cross-sectional view of an end of a probe according to some embodiments;

[0009] Figure 3B Another end cross-sectional view of a probe according to some embodiments Figure 3A ;

[0010] Figure 4 Isometric view of a cross-sectional area for fluid flow within a portion of a probe according to some embodiments

[0011] Figure 5 Another isometric view of a cross-sectional area for fluid flow within a portion of a probe according to some embodiments

[0012] Figures 6A - 6D Shows various channel designs according to some embodiments

[0013] Figure 7 Isometric view of a portion of a probe according to some embodiments

[0014] Figure 8A and 8B Isometric cross-sectional view of a portion of a probe according to some embodiments

[0015] Figure 9 Cross-sectional view of a probe tip according to some embodiments

[0016] Figure 10 Isometric view of a component of a probe according to some embodiments

[0017] Figure 11A and 11B Are other isometric cross-sectional views of a probe according to some embodiments

[0018] Figure 12 Is another isometric cross-sectional view of a probe according to some embodiments; and

[0019] Figure 13 Is a block diagram of a method of using a probe designed according to some embodiments DETAILED DESCRIPTION

[0020] The description of the preferred embodiments should be read in conjunction with the accompanying drawings, which are a part of the entire written description of these disclosures. While the present disclosure is susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and will be described in detail herein. The objects and advantages of the claimed subject matter will become more apparent from the following detailed description of these example embodiments in conjunction with the drawings

[0021] However, it should be understood that the present disclosure is not intended to be limited to the specific forms disclosed. On the contrary, the present disclosure covers all modifications, equivalents, and alternatives falling within the spirit and scope of these example embodiments. Terms such as "coupled," "coupled to," "operatively coupled," "operatively connected," etc. should be understood broadly to mean connecting devices or components mechanically, electrically, wired, wirelessly, or otherwise together such that the connection allows the relevant devices or components to operate (e.g., communicate) with each other as desired by virtue of that relationship.

[0022] Figure 1 A perspective view of a probe 100 in accordance with some embodiments presented herein is shown. The probe 100 may have a first member 102 having a first end portion 104 and a second end portion 106. The first member 102 may have an elongated hollow structure extending from the first end portion 104 to the second end portion 106. The structure may be tubular, having a generally circular inner diameter and outer diameter, and may have generally constant inner and outer dimensions (e.g., radius) between the first end portion 104 and the second end portion 106. The first end portion 104 is coupled to a handle 108. The first end portion 104 may be referred to as the proximal end of the first member 102 due to its connection to the handle 108. Similarly, the second end portion 106 may be referred to as the distal end of the first member 102 as it is further from the handle 108 and other devices (e.g., a fluid supply device, a fluid return device, an electrical connection device for a temperature sensor, etc.).

[0023] The first member 102 may include various materials, including stainless steel, Inconel, titanium, or other materials.

[0024] The handle 108 has two main functions. First, the handle 108 improves the surgeon's ability to physically manipulate the position and orientation of the probe. Second, the handle 108 may provide physical connections between the inlet and outlet fluid flow paths within the first member 102 and a fluid supply device and a fluid return device, respectively, and any electrical connections between components of the first member 102 and a support device. These connections may be physically combined into a bundle 110, and the bundle 110 may be operatively coupled to a refrigerant source 111 (which may include a fluid return device, or the return device may be separate therefrom), a console 113 (the refrigerant source 111 may be integrated with the console 113).

[0025] The fluid used by the probe 100 may include, but is not limited to, argon, gaseous nitrogen, helium, a refrigerant, liquid nitrogen, and other fluids.

[0026] Figure 2is a perspective cross-sectional view of a second end portion 106 of a probe 100 according to some embodiments. A first member 102 is coupled to a tip 112 at the distal most end of the probe 100. The tip 112 can be round or can be sharp to facilitate movement of the probe through tissue. A surface 120 of the tip 112 can engage a surface 122 of the first member 102. Once engaged, the tip 112 can be fixed to the first member 102. As Figure 2 shown, the surface 120 of the tip 112 can be located on a flange that engages an inner surface 122 of the first member 102, but other arrangements are also possible. The tip 112 can have an inner surface 124, as Figure 2 shown, which can be tapered, flat, round, or hollow.

[0027] Figure 2 A second member 114 is also shown. The second member 114 can provide at least a portion of a fluid path from a fluid supply source to the probe tip 112. The second member 114 can be positioned within the first member 102 such that the second member 114 extends within the first member 102. This extension can be adjacent to the second end portion 106 of the probe 100. This extension can be along a longitudinal axis of the first member 102, and the second member 114 can be centered about this longitudinal axis. However, not all embodiments are limited to this, and in some embodiments, the second member 114 can extend generally along the longitudinal axis of the first member 102 but be offset from the longitudinal axis. In some embodiments, the second member 114 can extend from a handle 108 at a first end portion 104 almost to the probe tip 112. The second member 114 can have an elongated hollow structure and can be tubular. The second member 114 can be composed of various materials, including stainless steel, copper, inconel, titanium, brass, ceramic, or other materials.

[0028] Like the second member 114, a third member 116 can have a hollow structure that extends along the longitudinal axis of the first member 102 and can be generally tubular. The third member 116 can be disposed externally along at least a portion of the extension of the second member 114 and can be radially outside the second member 114. In some embodiments, the third member 116 can be in contact with and fixed to the second member 114, for example, by brazing. A distal end 126 of the third member 116 can substantially surround a portion of the second member 114, for example, by being radially outside the second member 114. The second member 114 and the third member 116 can each have distal ends 128 and 126 that form a surface generally perpendicular to the longitudinal axis of the first member 102. As Figure 2 shown, the respective distal ends 128 and 126 of the second member 114 and the third member 116 can be coplanar with each other.

[0029] The third member 116 may include stainless steel, copper, ceramic, Inconel, titanium, brass, plastic, or other materials.

[0030] Figure 3A FIG. 4 is an end cross-sectional view of the probe 100 according to some embodiments, with the second member 114 omitted. As shown, the outer surface 130 of the third member 116 may engage the inner surface 122 of the first member 102 at one or more points 132. The third member 116 may be configured to have an outer dimension "D" that is sufficiently close to the inner dimension of the first member 102 such that the third member 116 remains in place with respect to the first member 102. The outer surface 130 of the third member 116 may also have one or more segments 134 with dimensions smaller than the outer dimension "D", where the dimensions of the segments 134 are measured along the longitudinal axis of the first member 102. The one or more segments 134, the engagement points 132, and the inner surface 122 of the first member 102 together define a passageway 136 that may extend along the longitudinal length of the third member 116. The one or more passageways 136 may be annular passageways. The segments 134 may be formed by machining the outer surface 130 of the third member 116.

[0031] In operation, fluid may flow through the passageway 136 between the third member 116 and the first member 102 after first passing through the region near the second member 114 and the tip 112. This region may cause the fluid to expand. By designing the passageway 136 to have a small cross-sectional area, most of the cooling fluid is closer to the inner surface 122 of the first member 102 compared to designs that use larger passageways (such as the designs mentioned below). Additionally, the fluid velocity in these passageways is higher than the fluid velocity in older designs (where the cross-sectional area of the fluid passageway is larger), as seen in U.S. Patent Application No. 2007 / 0149959, thereby reducing the fluid boundary layer thickness and promoting heat transfer between the fluid and the first member 102 that is in thermal communication with the surrounding tissue. These two features both contribute to improving the thermal performance of the probe disclosed herein.

[0032] In some embodiments, some of the passageways 136 may provide an inlet fluid flow path from the proximal end to the distal end of the probe 100, thereby replacing some or all of the functions and uses of the second member 114 as described above. In some embodiments, some other passageways 136 may provide an outlet fluid flow path from the distal end to the proximal end of the probe 100. In some embodiments, all of the passageways 136 may provide an inlet fluid flow path and the second member 114 may provide an outlet fluid flow path.

[0033] The inventors have found that the position of the cross-sectional area of the passageway 136 relative to the inner surface 122 of the first member 102 has a significant effect on thermal performance. These cross-sectional areas of the passageway 136 are taken perpendicular to the longitudinal (major) axis of the first member 102. AsFigure 3B As shown, this relative positioning of the cross-sectional area 152 of the passageway 136 can be defined by the percentage of the cross-sectional area located between the inner surface 122 of the first member 102 and a boundary 154 positioned inwardly from the inner surface 122 of the first member 102. This boundary is offset inwardly from the inner surface 122 of the first member 102 by a distance “D2” which is 10% of the maximum internal cross-sectional radius defined by the inner surface 122 of the first member 102. For example, in the case where the first member 102 has a circular inner cross-section, the boundary is a circle having a diameter that is 80% of the inner diameter of the first member 102. A significant improvement in thermal performance is observed when at least 70% of the total cross-sectional area of the passageway 136 is located in this area between the inner surface 122 of the first member 102 and this boundary. In some embodiments, at least 80% of the total cross-sectional area of the passageway 136 is located in this same area. In some embodiments, at least 90% of the total cross-sectional area of the passageway 136 is located in this area. In some embodiments, at least 100% of the total cross-sectional area of the passageway 136 is located in this area.

[0034] The inventors have also found that a specific ratio of the cross-sectional area of the passageway 136 to the cross-sectional area of the first member 102 shows an improvement in the thermal performance of the probe 100. In these ratios, the inner surface 122 of the first member 102 defines the cross-sectional area within the first member 102. The total flow cross-sectional area of the passageway 136 taken perpendicular to the longitudinal (main) axis of the first member 102 is defined by the engagement of the third member 116 with the first member 102. The ratio of the total flow cross-sectional area of the passageway 136 to the cross-sectional area that circumscribes itself within the first member 102 and that improves thermal performance includes from 0.05 to 0.3.

[0035] Figure 3A The cross-sectional profile of the third member 116 shown is a polygon that is generally hexagonal, having six contact locations 132 between the outer surface 130 of the third member 116 and the inner surface 122 of the first member 102, thereby jointly defining a total of six passageways 136 for fluid flow. This profile is merely an example. Figure 4 Another example is shown in Figure 4 is a perspective view of the cross-sectional area for fluid flow within a portion of the probe 100 according to some embodiments. This profile is largely similar to the profile provided in FIG. 3, however, the width of the location 132 where the outer surface 130 of the third member 116 engages with the inner surface 122 of the first member 102 is reduced, this width being measured perpendicular to the longitudinal axis of the first member 102 and generally around the circumference of the third member 116, such that the location 132 more resembles a contact point (or line, when viewed along the length of the third member 116) rather than an area, thereby giving the third member 116 six sides of a hexagon.

[0036] Figure 5 Another exemplary cross-sectional area for fluid flow is shown. As shown, the third member 116 engages the inner surface 122 of the first member 102 at four locations 132, thereby defining four passageways 136. Although this embodiment and the previous embodiments show the third member having a polygonal or substantially polygonal shape (desirably with curved portions connecting flat portions of the outer surface 130), the third member 116 is not limited to having a polygonal outer shape.

[0037] Likewise, the number of locations 132 where the outer surface 130 of the third member 116 engages the inner surface 122 of the first member 102 is variable and can be as few as one (which can extend over an area around the circumference of the third member 116) to two, three, four, five, six, or even more. Conversely, the number of engagement locations 132 between the third member 116 and the first member 102 determines the number of passageways between the two members.

[0038] POSA will recognize that other shapes of the third member 116 can still enable the features discussed herein to achieve improved thermal performance.

[0039] Multiple channels 138 can be formed within the outer surface 130 of the third member 116, which direct fluid flow within the passageways 136 and sometimes between the passageways 136. These channels 138 can have various shapes, such as Figures 6A - 6D shown, Figures 6A - 6D is a top view of the outer surface 130 of the third member 116 as viewed along the extension of the third member. It can be seen that these channels 138 can have a stepped shape, a series of alternating faces parallel and then perpendicular to the extension of the third member 116 ( Figure 6A ), a series of zigzag shapes ( Figure 6B ). In some embodiments, the shape can be similar to a zigzag, but a series of continuously curved surfaces are used ( Figure 6C ). In some embodiments, the channels 138 can spiral around the third member 116 along the extension of the third member 116 ( Figure 6D ). By changing the direction of fluid flow, the channels 138 can reduce the boundary layer thickness of the fluid, thereby increasing the heat transfer coefficient. POSA will recognize that other channel designs / patterns can be used to direct fluid flow within the passageways 136.

[0040] Returning to Figure 2In embodiments where the second member 114 extends through the length of the third member 116, the third member 116 can have a proximal end 140 that can be located radially outward of and surrounding the second member 114. The fourth member 118 is located between the handle 108 and the proximal end 140 of the third member 116. In some embodiments, the fourth member 118 serves as a return line for the fluid after the fluid flows through the passage 136. The fourth member 118 can be a double-walled structure with or without a vacuum or insulating material between the double walls, and insulates the proximal end of the first member 102 from the cold working fluid, thereby serving as the end point of the cooling portion of the first member 102. The fourth member 118 can be a hollow structure extending within the first member 102. The structure can be tubular and can include stainless steel, Inconel, titanium, ceramic, or other materials. As Figure 2 As shown, the fourth member 118 can be coaxial with and radially surround the second member 114 (or other member that provides at least a portion of the flow path of the fluid to the tip 112). In some embodiments, for example Figure 7 In the illustrated embodiment, a bulk head member 119 may be used to seal and isolate the inlet and outlet pipes, which may be the second member 114 and the fourth member 118, respectively. The inlet and outlet pipes may optionally be coaxial where they pass through the bulk head member 119. The area near the bulk head member 119 may be insulated by physical insulation, vacuum, or both.

[0041] The fourth member 118 and the member providing at least a portion of the inlet flow path (which may be the second member 114) may be surrounded by an insulating structure 142 between these members and the first member 102. The insulating structure 142 is used to reduce heat transfer between the tissue and fluid surrounding the first member 102, thereby serving as the end point of the working cooling portion of the first member 102. The insulating structure 142 may include a material with low thermal conductivity, such as ceramic, and a vacuum may be used to help reduce heat transfer. This vacuum may be permanent, as a vacuum is drawn in a sealed volume within the structure 142, or actively drawn by a pump during operation of the probe.

[0042] Steering Figure 8A , illustrates a probe 100 according to some embodiments, wherein the second member 114 includes an extension 144, in addition to Figure 8A The embodiment is largely similar to Figure 2 The extension 144 is used to impinge the fluid onto the inner surface 124 of the tip 112. In addition, the extension 144 of the second member 114 is used to reduce the flow cross-sectional area near the tip 112. These two features can increase the heat transfer rate closer to the tip 112.

[0043] like Figure 8AAs shown, the second member 114 and the third member 116 are positioned within the first member 102 such that the distance measured between the distal end 128 of the extension 144 of the second member 114 and the tip 112 is less than a second distance measured between the distal end 126 of the third member 116 and the tip 112. In some embodiments, the outer dimension "D" of the third member 116 may be greater than the inner dimension between the tip 112 and the junction of the first member 102. This larger dimension prevents the third member 116 from extending as far as the second member 114 to the tip. The outer dimension of the extension 144 is small enough such that it may extend within the tip 112 to a position radially enclosed by the surfaces 120 and 122 of the tip 112 and the first member 102, respectively.

[0044] In some embodiments, as Figure 8B shown, a spacer member 158 or a protrusion may be added to the distal face of the third member 116 to prevent the third member 116 and the second member 114 from extending too far in the distal direction towards the tip 112. For example, the spacer member 158 may have a combined width that is greater than the width of the proximal end of the tip 112 such that the spacer member 158 will engage the proximal surface of the tip 112, thereby preventing the third member 116 and the second member 114 from extending too far in the distal direction towards the tip 112.

[0045] An extension 146 may also be added to the third member 116 such that a portion of the third member 116 extends into the region within the tip 112 such that the extension 146 is radially enclosed by a portion of the tip 112, the first member 102, or both. Figure 9 Such an embodiment is shown in a cross-sectional view of the tip 112 of the probe 100 of. The third member 116 includes a first portion having an outer dimension "D" that is greater than the inner dimension of the tip 112, for example, between the surfaces 120 that engage the first member 102. The third member 116 may also include a second portion, namely the extension 146, having an outer dimension at the same location that is less than the inner dimension of the tip 112. The extension 146 further reduces the flow cross-sectional area of the fluid, thereby increasing the heat transfer coefficient of the fluid in the tip region in the same manner as described above for the passage 136 between the third member 116 and the first member 102, and is superior by providing only the extended second member 114.

[0046] In some embodiments, the third member 116 may have a portion 148 between a larger first portion and an extending second portion. The portion 148 may be smooth. As used herein, "smooth" describes a surface that is generally without discontinuities (or "continuous"). Between the distal and proximal endpoints of the portion 148 may be smooth, and between the first and second portions of the third member 116 may be smooth or have a gradual transition. This smooth transition provided by the portion 148 reduces the resistance to fluid flow within the probe 100.

[0047] Figure 10 is a perspective view of the third member 116 having an extension and a portion 148.

[0048] According to some embodiments, as Figure 11A shown, the probe 100 has a fifth member 160 adjacent the tip 112. Since the fifth member 160 does not extend along the entire length of the third member 116, a section 150 of the third member 116 provides at least a portion of the access fluid flow path upstream of the fifth member 160. The second member 114 may extend along the longitudinal axis of the first member 102 near the proximal end of the third member 116 and may engage the third member 116 to provide a portion of the inlet fluid flow path.

[0049] In some embodiments, the third member 116 may include the fifth member 160 in the form of an integral part, as Figure 11B shown. The third member 116 may still engage the second member 114 at its proximal end. Fabricating an integral third member 116 / fifth member 160 component that provides the functions of both the third member 116 and the fifth member 160 can simplify assembly by reducing the number of components that may need to be connected to each other.

[0050] As Figure 12 shown, the second member 114 may be surrounded by the third member 116 at the proximal end of the third member 116, and the second member 114 may provide a fluid flow path into the section 150 of the third member 116. This arrangement allows for a greater ability to exchange heat between the inlet fluid in the section 150 and the fluid flowing in the passageway 136 between the third member 116 and the first member 102. This internal heat transfer between the fluids makes the temperature more uniform along the length of the probe 100. As shown, the member 116 may have a first internal dimension at the distal and proximal ends where it engages the fifth member 160 and the second member 114, respectively, and a second internal dimension between its distal and proximal ends. This second internal dimension allows the fluid to flow closer to the passageway 136 and results in a reduced radial thickness of the section 150 of the third member 116 compared to the distal and proximal ends of the third member 116.

[0051] Figure 13FIG. 1300 is a block diagram of a method 1300 of using a probe designed in accordance with some embodiments. The method begins at block 1302. At block 1304, a probe designed in accordance with one or more embodiments provided herein is provided. Then, at block 1306, the probe is coupled to a fluid supply device and a fluid return device. At block 1308, the probe is positioned such that it contacts the target tissue. Then, at block 1310, fluid is supplied to the probe and then, at block 1312, the fluid is drained from the probe to the fluid return device. The method may end at block 1314. Those of ordinary skill in the art will recognize that other conventional methods and procedures for flowing fluid into and out of the probe may be used with the probe 100 described in the embodiments herein.

[0052] Improvements to the internal design of the cryoprobe have enhanced the cooling performance of the cryoprobe, which utilizes an internal fluid (liquid, gas, mixed, or other phase) as the cooling medium disclosed herein. These improvements increase the rate of heat transfer between the outer surface of the probe and the internal working fluid. The increased rate of heat transfer can be used to cool / freeze tissue more quickly, freeze a larger tissue area, consume less fluid or energy for the same cooling or freezing performance, result in a more uniform temperature along the probe, or any combination of the above advantages.

[0053] The foregoing is provided to illustrate, explain, and describe these disclosed embodiments. Modifications and changes to these embodiments will be apparent to those skilled in the art and may be made without departing from the scope or spirit of these disclosures.

Claims

1. A cryosurgical probe, comprising: A first member having an elongated hollow structure extending from a first end portion to a second end portion; A tip coupled to the first member at the second end portion; A second member having a hollow, tubular structure and positioned within the first member such that the second member extends within the first member; And A third member having a hollow structure extending along a longitudinal axis of the first member and operatively coupled to an inner surface of the first member to define at least one passageway between the third member and the first member, wherein the third member is disposed outwardly from the second member along at least a portion of the second member, and wherein a portion of the third member surrounds at least a portion of the second member, the second member providing an inlet fluid flow path from a distal end to a proximal end of the cryosurgical probe, and the at least one passageway providing an outlet fluid flow path from the distal end to the proximal end of the cryosurgical probe, Wherein the third member is positioned at a location along the second member in which, when the tip is coupled to the first member, a first distance between a distal end of the second member and the tip is less than a second distance between a distal end of the third member and the tip.

2. The probe according to claim 1, wherein the third member includes a first portion having a first size and a second portion having a second size smaller than the first size, and wherein the second portion is configured to abut the tip.

3. The probe according to claim 2, wherein the third member includes a continuous surface between the first portion and the second portion.

4. The probe according to claim 1, wherein at least a portion of the second member is surrounded by the tip and the first member.

5. The probe according to claim 1, wherein the third member has an outer width greater than an inner width of the tip at a location where the tip is configured to engage the first member.

6. The probe according to claim 1, wherein the third member further includes a plurality of protrusions extending from a distal end of the third member, the plurality of protrusions having a combined width greater than a width of the tip at a proximal end of the tip.

7. The probe according to claim 1, wherein the second member and the third member include different materials.

8. The probe according to claim 1, wherein the third member further includes a proximal end configured to surround the second member away from the tip and a distal end configured to surround a fifth member having a hollow structure near the tip, and wherein the third member has a first inner size at the distal end and the proximal end, the first inner size being less than a second inner size, the second inner size being perpendicular to the extension of the third member and located between the distal end and the proximal end of the third member.

9. The probe according to claim 1, wherein the third member includes an outer surface defining a plurality of channels, and the plurality of channels define a portion of the at least one passageway at a location where the third member engages the inner surface of the first member.

10. The probe according to claim 9, wherein the plurality of channels include a zigzag, stepped, or continuously curved shape along the length of the third member.

11. The probe according to claim 1, further comprising a fourth member configured to extend within the first member, wherein the fourth member is configured to be positioned adjacent to the first end portion of the first member and radially surround at least a portion of the second member.

12. The probe according to claim 1, wherein the third member includes an outer surface having a polygonal cross-sectional shape.

13. The probe according to claim 1, wherein the third member is configured to operably engage the inner surface of the first member at at least two locations.

14. The probe according to claim 1, wherein at least 70% of the cross-sectional area of the at least one passageway defined between the third member and the first member is outside a boundary that is offset inward from the inner surface of the first member by a distance equal to 10% of the maximum internal dimension between the inner surfaces of the first member.

15. The probe according to claim 1, wherein the ratio of the cross-sectional area of the at least one passageway defined between the third member and the first member to another cross-sectional area defined by the inner surface of the first member is less than 0.

3.

16. The probe according to claim 1, further comprising a thermal insulation member configured to surround the second member.

17. A cryosurgical system, comprising: A fluid supply device; A cryosurgical probe, comprising: A first member having an elongated hollow structure extending from a first end portion to a second end portion; A tip coupled to the first member at the second end portion; A second member having a hollow, tubular structure and positioned within the first member such that the second member extends within the first member; A third member having a hollow structure extending along a longitudinal axis of the first member and operably coupled to the inner surface of the first member to define at least one passageway between the third member and the first member, wherein the third member is disposed outwardly from the second member along at least a portion of the second member, and wherein a portion of the third member surrounds at least a portion of the second member, the second member providing an inlet fluid flow path from the distal end to the proximal end of the cryosurgical probe, and the at least one passageway providing an outlet fluid flow path from the distal end to the proximal end of the cryosurgical probe, wherein the third member is positioned at a location along the second member where, when the tip is coupled to the first member, a first distance between the distal end of the second member and the tip is less than a second distance between the distal end of the third member and the tip; and A fourth member extending within the first member, wherein the fourth member is positioned adjacent the first end portion of the first member; and A fluid return device fluidly coupled to the fourth member.

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