WO1996029944A1

WO1996029944A1 - Cold-chargeable cryosurgical device

Info

Publication number: WO1996029944A1
Application number: PCT/US1996/003915
Authority: WO
Inventors: Alexander Levin
Original assignee: Helfgott & Karas, P.C.; Cryo-Medical Products
Priority date: 1995-03-24
Filing date: 1996-03-22
Publication date: 1996-10-03
Also published as: IL113116A0; AU5320396A

Abstract

A cold-chargeable cryosurgical device includes a housing (18); a chargeable cold storage unit (37) located inside the housing; a probe portion (12) arranged in heat transfer association with the cold storage unit, and terminating in a probe tip (20); an apparatus for conducting a refrigerant (13) in heat exchange association with the cold storage unit (37), such that the refrigerant is cooled thereby, and for supplying the cooled refrigerant via the probe portion to the probe tip (20) so as to cause cooling thereof.

Description

COLD-CHARGEABLE CRYOSURGICAL DEVICE

FΪF.LD OF Ti m 1NVF.NTION

Tlie present invention relates to surgical devices generally, and to cryosurgical devices in particular

BACKGROUND OF THE INVENTION

Various surgical devices for performance of cryostiigical oi hypothermic procedures are known The fields in which such devices are used includes cryosurgical procedures on brain tumors, ophthalmology, otorhinolaryngology, gynecology, urology, proctology, general oncology, stomatology, dermatology and cosmetic surgery

Most known devices employ either liquid or solid cooling agents (for example, liquid mtiogen, solid carbon dioxide or liquid fieon) for generating a required cooling effect during evaporation thereof, or thermoelectric cooling

Devices employing cooling agents are characterized by seveial disadvantages, including the fact that it is necessary to periodically refill them, and that refilling these devices with a liquid cooling agent is a complicated procedure Furthermore, many of these devices use refrigerants which, once used, dissipate into the atmosphere, and thus cannot be icusecl

Thermoelectric devices, while also known Ibi the performance of cryosurgical and hypothermic medical procedures, require expensive temperature control systems and, furthermore, they are not convenient to use due to their relatively bulky heat sink radiators

Λ further indication of the state of the art is provided by US Patent No 5,452,582, entitled "Cryo-Probe" This patent discloses a cryo-probe to which a refiigerant is furnished from a high piessuie, room temperature supply, thereby rendering insulation of the icfπgerant lines unnecessary Rcfi igeianl Hows thiough a pie-cooling heat cxchangci in the pi obe and through a restπctor wherein the pressure drops In accordance with the Joule-Thompson effect, the refrigerant expands and becomes cold and liquid is applied in the region of the crγo-lιp lo piovide rapid cooling thereof Expanded refrigerant gas at low pressure reverses direction and flows back from the cold tip in counterflow arrangement through the aforementioned heal exchanger lo give a pre-cooling effect to the refrigerant incoming from the external supply Λ second tube for conveying warm-up gas is located in the probe and extends to the cold tip After cryosurgery is complete, the high pressure tlow is stopped and warm gas is delivered to the tip in the probe at reduced pressure through the second tube from the same refrigerant supply as is used for cooling Accordingly, the tip is rapidly warmed SUMMARY OF THE INVENTION

The present invention seeks to provide a novel cryosurgical device which does not require the use of large quantities of refrigerant, and which is essentially a cold-chargeable device.

A first embodiment of the invention employs a two-phase thermosiphon which is driven by a cold-charged reservoir, wherein a portion of the two-phase thermosiphon defines a probe end, and wherein the entire device is totally portable

A second embodiment of the invention employs a cold-charged reservoir for cooling a room- temperature refrigerant for circulation in thermally conductive contact with a probe end

There is thus provided, in accordance with a preferred embodiment of the present invention, a cold-chargeable cryosurgical device which includes a housing, a chargeable cold storage unit located inside the housing, a probe portion arranged in heat transfer association with the cold storage unit, and terminating in a probe tip, and apparatus for conducting a refrigerant in heat exchange association with the cold storage unit, such that the refrigerant is cooled thereby, and for supplying the cooled refrigerant via the probe portion to the probe tip so as to cause cooling thereof

Additionally in accordance with a preferred embodiment of the invention, the chargeable cold storage unit includes a cold-chargeable substance which undergoes a liquid-solid phase change at a predetermined cryogenic temperature, and a thermally conductive container for the cold-chargeable substance

In accordance with one embodiment of the invention, the device is a portable device and the apparatus for conducting a refrigerant is a two-phase thermosiphon arranged in heat exchange association with the cold storage unit and containing a fluid in both its liquid and vapor forms

Furthermore, the thermally conductive container has an elongate annular configuration which defines a central opening, and the two-phase thermosiphon includes an elongate, thermally conductive container having a pair of ends, one of which constitutes the probe portion, and wherein the container is mounted within the opening of the annular container in thermal exchange association therewith, and such that the probe portion and the probe tip protrude therefrom

In the present embodiment, when the cold storage unit is at a cryogenic temperature, vapors within the two-phase thermosiphon in thermal exchange association with the cold storage unit are condensed into liquid form which tends to flow downward under gravitational forces.

In accordance with an alternative embodiment of the invention, the apparatus for passing a refrigerant in heat exchange association with the cold storage unit includes a refrigerant inlet. a refrigerant outlet; a supply conduit connected to the inlet, for conducting therefrom a refrigerant at non- cryogenic temperatures into heat exchange association with the cold storage unit so as to cool the refrigerant to a cryogenic temperature, and for supplying the cooled refrigerant to the probe portion and to the probe tip, whereat thermal energy is transferred from an outside source, via the probe tip, to the cryogenically cooled refrigerant so as to partially heat the refrigerant; and a return conduit connected to the outlet, for conducting the partially heated refrigerant away from the probe tip to the outlet.

Additionally in accordance with the present embodiment the refrigerant is supplied at a first, relatively warm temperature, and the partially heated refrigerant conducted away from the probe tip has a second temperature, lower than the first temperature, and the device further includes a countertlow heat exchanger

The countertlow heat exchanger includes a first passage for conveying the refrigerant from the inlet to the supply conduit; a second passage, generally parallel to the first passage, for conveying the partially heated refrigerant from the return conduit to the outlet; and apparatus for facilitating anisotropic thermal energy transfer from the refrigerant in the first passage to the partially heated refrigerant in the second passage

Preferably, the apparatus for facilitating anisotropic thermal energy transfer includes a plurality of thermally conductive disks having formed therein a first plurality of openings, and a plurality of thermally insulative disks having formed therein a second plurality of openings, wherein the first plurality of openings have a similar size and shape to those of the second plurality of openings, and the first plurality of openings are formed in the thermally conductive disks and the second plurality of openings are formed in the thermally insulative disks so as to be similarly located with respect to the disks, such that the thermally conductive and thermally insulative disks can be placed on top of each other such that the first and second pluralities of openings are in mutual registration, and wherein the thermally conductive and thermally insulative disks are stacked in an alternating arrangement, so as to define the first and the second passage therethrough, thereby to permit the supply of the refrigerant and the conveying of the partially heated refrigerant in generally parallel, opposite directions, respectively, wherein the thermally conductive disks are operative to permit heat transfer from the refrigerant to the partially heated refrigerant in a lateral direction, and the thermally insulative disks are operative to reduce heat loss from the partially heated freezing in a longitudinal direction. BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more easily understood and appreciated from the following detailed description, taken in conjunction with the drawings, in which

Figs 1 Λ and IB are longitudinal side-sectional views of a cryosurgical device constructed in accordance with a first embodiment of the invention, seen in charging' and 'use' modes, respectively.

Fig 2 A is a longitudinal side-view of a cryosurgical device constmcted in accordance with an second embodiment of the invention;

Fig 2B is a cross-sectional view of the cryosurgical device of Fig 2 A, along line B-B therein,

Fig 3 A is an enlarged side-sectional view of counterfiow apparatus employed in the device of Fig 2Λ. and

Figs 3B, 3C and 3D are cross-sectional views of the countertlow apparatus seen in Fig. 3 A, along respective lines B-B, C-C and D-D therein

DETAILED DESCRIPTION OF THE INVENTION Referring now to Figs 1 A and IB, there is seen a portable crvosurgical device, referenced generally 10, constructed and operative in accordance with a first embodiment of the present invention The construction of the cryosurgical device 10 for performance of cryosurgical or cosmetic procedures is based on use of substances which have a suitable melting temperature, the latent heat released by melting of these substances is used for freezing human tissue These substances are those which have been previously frozen, at least in part, by means of a refrigerant, such as, liquid nitrogen or liquid carbon dioxide, or by contact with a separate low-temperature freezing device

Cryosurgical device 10 has a typically elongate, generally cylindrical configuration, and has a centrally located two-phase thermosiphon or heat pipe, referenced 12, which has first and second ends 14 and 16, and which is mounted in a tubular housing 18 such that first and second ends 14 and 16 protrude from housing 16 Two-phase thermosiphon 12 is a sealed tube construction formed of a substance having high thermal conduction properties, such as copper or brass First tube end 14 is sealed by a "cryo-tip" or probe tip 20, and second end 16 is sealed by means of a filler construction having a valve 22 and plug 24, via which the two-phase thermosiphon 12 may be filled with a suitable low-boiling liquid and its vapor, referenced 13, typically Freon 13 or Freon 23 An inward-facing surface 26 of probe tip 20 may be provided with any suitable porous coating 28, such as sintered copper powder, in order to increase the heat transfer coefficients of the low-boiling liquid thereat In the present embodiment, it is seen that probe end 20 has a generally flattened configuration, rendering it suitable, inter alia, for dermatological applications

Tubular housing 18 is sealed at first and second ends 30 and 32, by means of respective annular inserts 34 and 36 through which two-phase thermosiphon 12 extends, thereby to form a cold-chargeable unit 37, having a sealed cylindrical, annular space, referenced generally 38, formed between the two-phase thermosiphon 12, the housing 18, and the inserts 34 and 36 Unit 37 contains a cold-chargeable substance 40 which changes its phase state at a predetermined temperature, or in a predetermined range of temperatures, and whose function is described below Typically, substance 40 is an anti-freeze substance such as ethylene glycol, having a freezing temperature in the range - 65°C - -85°C

In order to facilitate optimal thermal transfer between the two-phase thermosiphon 12 and the cold-chargeable substance 40, a plurality of radially extending metal fins 39 is provided on the exterior of two-phase thermosiphon 12, throughout space 38 of unit 37 Fins 39 are preferably made of copper or aluminum There may optionally be added to the cold-chargeable substance 40, a suitable powder filler which improves the thermal conductivity of substance 40

Cryosurgical device 10 is insulated by means of a cylindrical thermal insulation sleeve 42, mounted onto the exterior of housing 18, and, further, by means of a generally conical insulation cuff 44 (Fig I B), provided so as to cover a major portion of first end 14 of the two-phase thermosiphon 12 Cuff 44 is preferably detachable, thereby to enable cold charging of the chargeable unit 37 of the cryosurgical device, as seen in Fig 1 A, and as described below Optionally, probe tip 20 may also be provided with a temperature sensor (not shown) for measuring the temperature thereat during use

Referring now particularly to Fig 1 A, in order to charge substance 40 contained in cold- chargeable unit 37 with low-temperature cold, the insulation cuff 44 is removed from probe end 14, thereby to expose a portion of the two-phase thermosiphon, and this exposed portion is brought into contact with a cold source 46, for example, a low-temperature freezer of any suitable type known in the art During the cold-charging process it is important that the device 10 be held generally vertical, with probe tip 20 in a generally upwards orientation It is seen that, when device 10 is held in a generally vertical position, a portion of low-boiling substance 13 collects in second end 16 of the two-phase thermosiphon A further portion of substance 13, which is relatively warm, and which is thus in vapor form, collects in the space not taken up bv the liquid portion, and, due to its relatively low density and to the pressure difference generated between the first and second ends 14 and 16, tends to flow upwards, as indicated by arrows 48, towards first end 14 Heat transfer from the probe tip 20 to the cold source 46 is indicated schematically by arrows 49

The temperature of the cold source 46 is mitiallv lower than that of cold-chargeable substance 40, and is sufficiently low so as to cause any of the relatively warm vapor of the low- boiling substance 13 contained in two-phase thermosiphon 1 and coming into contact with the wall of the first end 14 of the two-phase thermosiphon, to condense into liquid form It will thus be appreciated that a cycle is set up whereby low-boiling substance 1 in the second end 16 of the two- phase thermosiphon is evaporated by the initially, relatively warm cold-chargeable substance 40 Vapors of low-boiling substance 13 flow upwards, and come into contact with the relatively cold surface of the first end 14 of the two-phase thermosiphon, so as to be converted back into liquid form The condensed liquid flows, under the influence of gravity, back down along the two-phase thermosiphon wall, as shown by arrows 50, into thermal contact with the cold-chargeable substance 40 The condensed liquid is then evaporated once again, and once again flows upwards

The repeated evaporation of the condensed liquid is caused by the latent heat in the cold- chargeable substance 40, resulting in cooling thereof This continues until substantially no more evaporation of the condensed liquid occurs, thus indicating thermal equilibrium between the cold- chargeable substance 40 and the cold source 46, and a desired cooling or freezing of the cold- chargeable substance 40 in unit 37

After termination of the charging process the device 10 is removed from cold source 46 and insulation cuff 44 is replaced onto probe end 14

Referring now to Fig I B, in use, the cryosurgical device 10 is seen to be generally inverted, such that the probe tip 20 is in a generally downwards onentation, such that the low-boiling liquid 13 collects in the first end 14 of the two-phase thermosiphon 12, in thermally conductive contact with probe tip 20 The probe tip is held against tissue, typically skin tissue, shown schematically at 52, so as to provide cryogenic cooling thereof

The relatively warm tissue 52 is cooled by transfer of heat energy to the probe tip 20, and, thereafter, to the low-boiling liquid 13 The thermal energy thus transferred to the liquid 13 causes partial evaporation of the liquid, such that vapors thereof flow upwards towards second end 16 of the two-phase thermosiphon 12, as shown schematically by arrows 5 As the vapor flows upwards, it is condensed back into liquid form as it contacts the interface between two-phase thermosiphon 12 and cold-chargeable unit 37. The liquid formed in this way flows downwards along the wall surface, as shown by arrows 56, thereby to replenish the volume of low-boiling liquid 13 adjacent to the probe tip 20 This cycle continues for a number of minutes, until the cold-chargeable substance 40 becomes warmed to non-cryogenic temperatures and melts, this typically, although not necessarily, coinciding with thermal equilibrium being reached between cold-chargeable substance 40 and the low-boiling liquid 13 At this stage, unit 37 must once again be charged with cold, as described above in conjunction with Fig. 1A Typically, the device 10 of the present embodiment may take approximately 20 minutes to become fully charged, and may take about 5 minutes to become discharged

In an alternative embodiment of the invention, the device 10 may be cold-charged by removing insulation sleeve 42, and by directly exposing the cold-chargeable unit 37 to an appropriate cold source

Referring now to Figs 2A and 2B, there is shown a cryosurgical device, referenced generally 100, constructed and operative in accordance with a second embodiment of the present invention It will be appreciated that, while the present embodiment is not totally portable as is device 10 shown and described above in conjunction with Figs. 1 A and 1 B, it is also a cold-chargeable device which, as will be appreciated from the following description, obviates the necessity of supplying a refrigerant at cryogenic temperatures

It will further be appreciated from the description that follows, that the present embodiment more easily enables provision of a long probe with a very small diameter end, thereby rendering it suitable for fine cryosurgical procedures, such as in ophthalmology or neurosurgery

Cryosurgical device 100 is formed of a generally tubular housing 102 on which is provided a detachable thermal insulation sleeve 103, a tubular, refrigerant supply conduit 104 extending axially through housing 102 The refrigerant may be any suitable antifreeze liquid, such as an ethanol-based substance A refrigerant return conduit 105 is arranged coaxially with and inside supply conduit 104 There are also provided annular end members 106 and 108, thereby to define together with housing 102 and supply conduit 104 a cold-chargeable unit 109, containing a sealed annular space 1 10. Unit 109 contains a cold-chargeable substance 1 12, such as ethylene glycol, which changes its phase state at a predetermined temperature, or in a predetermined range of temperatures, typically in the range -65°C - -85°C, and which functions as a "cold-charging" means In order to facilitate optimal thermal transfei from cold-chargeable substance 1 12 in unit 109 to a cooling fluid passing through supply conduit 104, there is preferably provided a plurality of radially extending metal fins 1 14 on the exterior of supply conduit 104, throughout the space 1 10 There may optionally be added to the cold-chargeable substance 1 12, a suitable powder filler which improves the thermal conductivity thereof

There is preferably also provided, at a rear end 1 16 of the cryosurgical device 100, a countertlow heat exchanger, referenced generally 1 18, having a layer 1 19 of a thermal insulation material provided thereabout As described in greater detail below, in conjunction with Figs 3A-3D, heat exchanger 1 18 is operative to reduce coid losses, and thus to extend the time that the device 100 av be used before recharging thereof is required

Device 100 has an elongate front end portion 120 which tapers to a probe tip 122, as seen in Fig 2A Probe tip 122 may have a diameter which is as small as 2 - mm or less Front end portion 120 is connected to cold-chargeable unit 109 via a connectoi member 1 4, through which conduits 104 and 105 extend Supply conduit 104 terminates in a manifold member 126, through which a refrigerant is supplied to the interior of front end portion 120 thereby to cool probe tip 122 Return conduit 105 extends through connector member 124 and defines a return fluid port 107 adjacent to probe tip 122, such that refrigerant flowing past probe tip 122, and which thus becomes relatively warmed, does not mix with cooler refrigerant upstream of the probe tip A conical outer jacket, referenced 128, is spaced apart from and mounted onto an inner wall portion 130 of front end portion 120 The space between the outer jacket 128 and wall portion 130, referenced 132, is evacuated so as to thermally insulate the interior of the probe front end portion 120

There is also provided a bypass conduit 134 which connects directly into supply conduit 104 as via connector member 124, and which, as described below, facilitates supply of a room- lemperature refrigerant directly to probe tip 122, so as to enable thawing thereof So as to accommodate the bypass conduit 134, insulation sleeve 103 has formed therein a longitudinal opening 136, and, further, has an additional strip of thermal insulation, referenced 138 (Fig 2B)

Preferably, the cold-chargeable unit 109 and front end portion 120 are formed as a single unit, and are not separable In accordance with an alternative embodiment of the invention, however, cold-chargeable unit 109 and front end portion 120 are formed so as to be mutually separable, in which case, the interface between unit 109 and portion 120 is provided with appropriate sealing fittings

Referring now also to Fig 3 A, counterflow heat exchanger 1 18 is provided so as to reduce cold loss from the device Heat exchanger 1 18 is formed of a stack of alternating thermally conductive disks 140, seen in Fig. 3B, and insulating disks 142, seen in Fig. 3C. Conductive disks 1 0 are typically made of metal, such as copper or aluminum, and insulating disks 142 are typically made of a polymer. Each disk 140 has formed therein a central first opening 144 and a plurality of radially distributed second openings 146. Each disk 142 has formed therein a central first opening 144' and a plurality of radially distributed second openings 146'. As seen in the drawings, disks 140 and 142 are of equal size, and the first and second openings are formed at corresponding locations tnerein. The stack of disks is thus arranged such that each of the respective first openings 144 and 1 4', and second openings 146 and 146' is located in coaxial registration with a counterpart opening in an adjacent disk, thereby to form a single central first passage 144" and a plurality of radially- spaced second passages 146", as seen in Fig. 3 A.

The stack of disks is held together between first and second bushings, respectively referenced 148 and 150. First bushing 148 is shown also in Fig. 3D It is seen that first bushing 148 is a manifold-type member, and has an inlet fluid port 152 through which refrigerant enters, first into a donut-shaped volume 1 54, and, which thereafter flows into second passages 146" Second bushing 150 is also a manifold-type member and has formed therein a donut-shaped volume 156 which communicates, via a plurality of openings 158, with supply conduit 104 (Fig. 2A). Accordingly, refrigerant which is supplied via inlet port 152 and volume 154, passes through second passages 146", and enters supply conduit 104 via donut-shaped volume 156 and openings 158. First and second bushings 148 and 150 also have formed therein central openings, respectively referenced 160 and 162, which are aligned with first passage 144", and together therewith, are operative to receive a return flow of refrigerant exiting through return conduit 105

It will thus be appreciated that, notwithstanding the fact that the flow through the counterflow heat exchanger 1 18 is in an axial, longitudinal direction, heat exchanger 1 18 is constructed so as to have anisotropic thermal conductivity, i.e - good thermal conductivity in the direction which is normal to direction of a cryoagent flow and low thermal conductivity in the direction of the refrigerant flow. This is due to the fact that the thermally conducting disks 140 are relatively thin and conduct heat radially inward, from the room-temperature refrigerant entering device 100 to the much cooler exiting return flow of refrigerant, while the insulating disks 142 are operative to prevent substantial transfer of heat from one metal disk 140 to another, in an axial direction. This enables more prolonged use of the device 100 prior to recharging, than would be possible without use of the counterflow heat exchanger 1 18

Cryosurgical device 100 of the present embodiment thus provides a number of advantages, including a) optimal usage of the cold of 'waste' or returned refrigerant for at least partially cooling, via counterflow heat exchanger 1 18, room-temperature refrigerant entering the cryoprobe, and b) the ability to use non-insulated pipes for supplying the refrigerant, due to the fact that it is supplied at room temperature, cooling thereof occurring inside the device 100

Referring now particularly to Fig 2 A, use of the cryosurgical device 100 of the present embodiment is as follows

Prior to use, cold-chargeable unit 109 must be charged with cold This is done by removal of insulation sleeve 103 and by subiecting the unit 109 to a suitable cold source (not shown), thereby to cool low melting substance 1 12 to a predetermined temperature

Subsequently, the fully-charged cryosurgical device 100 is removed from the cold source, its insulation sleeve 103 is replaced, and a refrigerant, which mav be at room temperature (for example, in the range 15°C - 25°C) is pumped into the device via inlet port 152 The refrigerant flows under pressure through heat exchanger 1 18, as descπbed above and as indicated by the arrows 164, flows through cold unit 109, whereat the refrigerant is cooled to a desired cryogenic temperature Subsequently, the refrigerant reaches probe tip 122, so as to cool it and thereafter to maintain it at a desired cryogenic temperature The refrigerant subsequently returns, through return conduit 105, as shown by arrows 166, and is warmed as thermal energy is conducted thereto via the thermally conductive disks 140 as it passes through heat exchanger 1 18, and exits device 100 via outlet port 168

In order to provide thawing of the probe tip 122 room-temperature refrigerant is introduced into front end portion 120 of device 100 via bypass conduit 1 34 so as to be circulated past the probe tip 122 The refrigerant - now having a somewhat lower temperature - is then removed from the cryosurgical device via return conduit 105

It will be appreciated by persons skilled in the art that the scope of the present invention is not limited to what has been specifically shown and described hereinabove, merely by way of example Rather, the scope of the present invention is limited solely by the claims, which follow

Claims

1 A cold-chargeable cryosurgical device which comprises a housing; chargeable cold storage means located inside said housing, a probe portion arranged in heat transfer association with said cold storage means, and terminating in a probe tip; and means for conducting a refrigerant in heat exchange association with said cold storage means, such that said refrigerant is cooled thereby, and for supplying said cooled refrigerant via said probe portion to said probe tip so as to cause cooling thereof.

2 A cryosurgical device according to claim 1 , wherein said chargeable cold storage means comprises a cold-chargeable substance, which undergoes a liquid-solid phase change at a predetermined cryogenic temperature; and thermally conductive means for containing said cold-chargeable substance.

3 A cryosurgical device according to claim 2, wherein said device is a portable device and said means for conducting a refrigerant comprises a two-phase thermosiphon arranged in heat exchange association with said cold storage means and containing a fluid in both liquid and vapor forms.

4 A cryosurgical device according to claim 3, wherein said thermally conductive means for containing said cold-chargeable substance is an elongate annular container defining a central opening, and said two-phase thermosiphon comprises an elongate, thermally conductive container having a pair of ends, one of which constitutes said probe portion, and wherein said container is mounted within said opening of said annular container in thermal exchange association therewith, and such that said probe portion and said probe tip protrude therefrom

5 A cryosurgical device according to claim 4, wherein, when said cold storage means is at a cryogenic temperature, vapors within said two-phase thermosiphon in thermal exchange association with said cold storage means are condensed into liquid form which tends to flow downward under gravitational forces.

6 A cryosurgical device according to claim 5, and comprising additional means, arranged in thermally conductive association with said cold-chargeable substance and said two-phase thermosiphon, for conducting thermal energy therebetween

7 A cryosurgical device according to claim 6, wherein said additional means comprises a plurality of fin portions mounted onto the exterior of said two-phase thermosiphon, and extending radially outward therefrom into said cold-chargeable substance

A cryosurgical device according to claim 5, and comprising a porous coating provided on an inward-facing surface of said probe tip, for increasing the heat transfer coefficient of said refrigerant thereat.

9 A cryosurgical device according to claim 2, wherein said means for passing a refrigerant in heat exchange association with said cold storage means comprises: refrigerant inlet means; refrigerant outlet means; supply conduit means connected to said inlet means, for conducting therefrom a refrigerant at non-cryogenic temperatures into heat exchange association with said cold storage means so as to cryogenically cool said refrigerant, and for supplying said cryogenically cooled refrigerant to said probe portion and to said probe tip, whereat thermal energy is transferred from an outside source, via said probe tip, to said cryogenically cooled refrigerant so as to partially heat said refrigerant; and return conduit means connected to said outlet means, for conducting said partially heated refrigerant away from said probe tip to said outlet means

10 A cryosurgical device according to claim 9, wherein said refrigerant is supplied at a first, relatively warm temperature, and said partially heated refrigerant conducted away from said probe tip has a second temperature, lower than said first temperature, and wherein said device further comprises: counterflow heat exchange means which comprises: first passage means for converting said refrigerant from said inlet means to said supply conduit means; second passage means, generally parallel to said first passage means, for conveying said partially heated refrigerant from said return conduit means to said outlet means; and means for facilitating anisotropic thermal energy transfer from said refrigerant in said first passage means to said partially heated refrigerant in said second passage means.

1 1. A cryosurgical device according to claim 10, wherein said means for facilitating anisotropic thermal energy transfer comprises: a plurality of thin, thermally conductive disks having formed therein a first plurality of openings; and a plurality of thermally insulative disks having formed therein a second plurality of openings, wherein said first plurality of openings have a similar size and shape to those of said second plurality of openings, and said first plurality of openings are formed in said thermally conductive disks and said second plurality of openings are formed in said thermally insulative disks so as to be similarly located with respect to said disks, such that said thermally conductive and thermally insulative disks can be placed on top of each other such that said first and second pluralities of openings are in mutual registration, and wherein said thermally conductive and thermally insulative disks are stacked in an alternating arrangement, so as to define said first and said second passage means therethrough, thereby to permit said supply of said refrigerant and said conveying of said partially heated refrigerant in generally parallel, opposite directions, respectively, wherein said thermally conductive disks are operative to permit heat transfer from said refrigerant to said partially heated freezing in a lateral direction, and said thermally insulative disks are operative to reduce heat loss from said partially heated freezing in a longitudinal direction.

12 A cryosurgical device according to claim 9, and comprising additional means, arranged in thermally conductive association with said cold-chargeable substance and said supply conduit means, for conducting thermal energy therebetween

13 A cryosurgical device according to claim 12, wherein said additional means comprises a plurality of fin portions mounted onto the exterior of said supply conduit means, and extending radially outward therefrom into said cold-chargeable substance.

14. A cryosurgical device according to claim 9, and also including bypass conduit means for facilitating supply of refrigerant at non-cryogenic temperatures directly to said probe portion and to said probe tip, thereby to provide thawing of said probe tip

15 A cryosurgical device according to any of claims 1 - 14, and substantially as shown and described hereinabove in conjunction with any of Figs 1 A-3D

16. A cryosurgical device according to any of claims 1 - 14, and substantially as shown in any of Figs. 1A-3D