CRYOPROBE WITH STIFFENING ELEMENT

Abstract

Aspects of the present invention provide miniaturized cryoprobes having shaft diameters up to 2 mm and including a stiffening element that may act as a grip for manipulation of the cryoprobe.

Various aspects of the present disclosure are generally directed towards apparatuses, systems, and methods that may include a cryoprobe: In certain instances, the cryoprobe may include an elongate shaft and an operating head having an expansion chamber. The elongate shaft may include a first passageway configured to provide high pressure gas to the expansion chamber, a second passageway for evacuating gas from the expansion chamber, and a vacuum chamber coaxially arranged around the first passageway and the second passageway.

Claims

1. A cryoprobe, comprising: an elongate shaft having a distal end and a proximate end; an operating head at the distal end of the elongate shaft, wherein the operating head comprises an expansion chamber; the elongate shaft comprising: a first passageway configured to provide high pressure gas to the expansion chamber and wherein the first passageway terminates in a Joule-Thomson orifice at its distal end; a second passageway for evacuating gas from the expansion chamber, wherein the second passageway is coaxially arranged around the first passageway; and a vacuum chamber coaxially arranged around the first passageway and the second passageway; the cryoprobe additionally comprising an elongate stiffening element located towards the distal end of the elongate shaft configured to reduce flexing of the elongate shaft.

2. A cryoprobe according to claim 1 wherein a cross section of the elongate shaft is from 0.9 to 2.0 mm in diameter.

3. A cryoprobe according to claim 1 wherein the shaft and operating head combined extend distally beyond the stiffening element up to 100 mm.

4. A cryoprobe according to claim 1 wherein the stiffening element is arranged coaxially about the elongate shaft.

5. A cryoprobe according to claim 1 wherein the stiffening element is configured as a grip for manipulation of the cryoprobe.

6. A cryoprobe according to claim 1 wherein the cryoprobe additionally comprises a grip for manipulation of the cryoprobe.

7. A cryoprobe according to claim 6 wherein the grip is hollow.

8. A cryoprobe according to claim 1 further comprising a single heat exchange arrangement consisting of an exchange of heat energy between the first passageway and the second passageway, the first and second passageways being arranged linearly and concentrically within the shaft.

9. A cryoprobe according to claim 1 wherein the operating head is from 2 to 7 mm in length.

10. A cryosurgical system comprising a cryoprobe and a source of cryofluid and a control configured to control a delivery of cryofluid to the cryoprobe; the cryoprobe comprising: an elongate shaft having a distal end and a proximate end; an operating head at the distal end of the elongate shaft, wherein the operating head comprises an expansion chamber; the elongate shaft comprising: a first passageway configured to provide high pressure gas to the expansion chamber and wherein the first passageway terminates in a Joule-Thomson orifice at its distal end; a second passageway for evacuating gas from the expansion chamber, wherein the second passageway is coaxially arranged around the first passageway; and a vacuum chamber coaxially arranged around the first passageway and the second passageway; the cryoprobe additionally comprising an elongate stiffening element located towards the distal end of the elongate shaft configured to reduce flexing of the elongate shaft.

11. A cryosurgical system according to claim 10 wherein a cross section of the elongate shaft is from 0.9 to 2.0 mm in diameter.

12. A cryosurgical system according to claim 10 wherein the shaft and operating head combined extend distally beyond the stiffening element up to 100 mm.

13. A cryosurgical system according to claim 10 wherein the stiffening element is arranged coaxially about the elongate shaft.

14. A cryosurgical system according to claim 10 wherein the stiffening element is configured as a grip for manipulation of the cryoprobe.

15. A cryosurgical system according to claim 10, wherein the cryoprobe additionally comprises a grip for manipulation of the cryoprobe.

16. A cryosurgical system according to claim 15 wherein the grip is hollow.

17. A cryosurgical system according to claim 10 further comprising a single heat exchange arrangement consisting of an exchange of heat energy between the first passageway and the second passageway, the first and second passageways being arranged linearly and concentrically within the shaft.

18. A cryosurgical system according to claim 10 wherein the operating head is from 2 to 7 mm in length.

19. A method of ablating a patient tissue, the method comprising: placing a tip of a cryoprobe within or adjacent to tissue to be ablated, the cryoprobe comprising: an elongate shaft having a distal end and a proximate end; an operating head at the distal end of the elongate shaft, wherein the operating head comprises an expansion chamber; the elongate shaft comprising; a first passageway configured to provide high pressure gas to the expansion chamber and wherein the first passageway terminates in a Joule-Thomson orifice at its distal end; a second passageway for evacuating gas from the expansion chamber, wherein the second passageway is coaxially arranged around the first passageway; and a vacuum chamber coaxially arranged around the first passageway and the second passageway; the cryoprobe additionally comprising an elongate stiffening element located towards the distal end of the elongate shaft configured to reduce flexing of the elongate shaft; delivering a cryogas to the Joule-Thomson orifice, via the first passageway, at a pressure sufficient to cause cooling of the tip of the probe to a cryogenic temperature to freeze patient tissue in contact with the probe tip; and subsequently thawing the tissue.

20. A method according to claim 11 wherein the tissue is thawed by delivering a warming gas to the Joule-Thomson orifice at a pressure sufficient to cause warming of the probe tip thereby thawing the tissue.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Aspects of the invention will now be described further by way of the following non limiting examples with reference to the figures. These are provided for the purpose of illustration only and other examples falling within the scope of the claims will be readily apparent to those skilled in the art in the light of these. All literature references cited herein are incorporated by reference.

[0061] FIG. 1 is a simplified illustration of features of the cryoprobe shaft, shown in cross section. FIG. 1A illustrates a joint arrangement between the operating head and the shaft in higher magnification.

[0062] FIG. 2 is a pictorial view of a bent shaft arrangement of the cryoprobe.

[0063] FIG. 3 is a simplified illustration of features of the cryoprobe with an example of a stiffening element. The device is shown in cross section.

[0064] FIG. 4 is a simplified illustration of features of the cryoprobe with a further example of a stiffening element. The device is shown in cross section.

EXAMPLE

[0065] Cryoneedles were constructed according to the description above having an inlet tube of 0.18 mm inner diameter and 0.33 mm outer diameter. An outer tube of 0.72 mm inner diameter and an overall diameter of 1.2 mm including the vacuum sleeve. The operating head was approximately 5 mm in length. The whole device from tip to proximal end of the tail was 3 m in length and the shaft and operating head combined extended from the stiffening element by 30 mm.

[0066] Using argon delivered at 3500 psi these needles produced ice balls of 10 mm in diameter in 2 minutes, 14 mm in diameter at 3.5 minutes, and 15 mm in diameter at 5 minutes.

DETAILED DESCRIPTION

Figures

[0067] FIG. 1 represents a cross section of a simplified view through a cryoprobe (1). The cryoprobe (1) has an elongate shaft (2) including an operating head (5) having tip (16). The elongate shaft (2) encloses a first passageway (3) which is co-extensive with an inlet tube (17). A second passageway (4) is co-extensive with an outlet tube (18). The first passageway (3) and second passageway (4) are concentric, wherein the second passageway (4) surrounds the first passageway (3). The second passageway (4) may be open to the atmosphere proximally via an outlet (19).

[0068] The operating head (5) comprises an operating head proximal chamber (20) surrounded by chamber walls (21) and distally by a distal end wall (25). The outlet tube (18) may project into the proximal chamber (20) of the operating head (5). An expansion chamber (6) may be formed between the distal end (24) of the outlet tube (18) and the distal end wall (25) of the operating head proximal chamber (20). The expansion chamber may be bounded by the inner walls (23) of the operating head proximal chamber (20). The distal most end (26) of the inlet tube (17) typically projects into the expansion chamber (6) and may terminate in a Joule-Thomson orifice (7) which is formed at the distal most end of the first passageway (3).

[0069] The inlet tube (17) is configured to deliver a cryogas under pressure from a cryofluid source (not shown in this figure). The cryogas expands on exiting the Joule-Thomson orifice (7) and evacuates via the outlet tube (18) to atmosphere at the opening (19).

[0070] The elongate shaft (2) further comprises a vacuum chamber (8) bounded externally by an outer circumferential vacuum chamber wall (27) and internally by the wall (22) of the outlet tube (18). The vacuum chamber is configured to thermally insulate the shaft proximal of the operating head and so prevent tissue damage proximal to the intended ice ball. Distally, the vacuum chamber wall (27) is tapered (14) and is a push fit over the outlet tube (18) at this point to provide a union between the two tubes (41). The vacuum chamber wall (27) may be welded or brazed to the wall of the outlet tube (18) in a vacuum furnace before being attached to the operating head. The distal most end (24) of the outlet tube (18) may project beyond the tapered end of the wall of the vacuum chamber (14) so as to be insertable into the proximal portion (28) of the operating head proximal chamber (20). The proximal end (29) of the wall (21) of the operating head proximal chamber (20) may be abutted against the distal end (30) of the vacuum chamber outer wall (27) to provide a circumferential indentation (31) between the vacuum chamber outer wall (27) and the proximal end (29) of the operating head distal chamber wall (21). The operating head (5), the vacuum chamber outer wall (27), and the outlet tube (18) can be welded or soldered together at this point (15) to seal the vacuum tube and hold the head in place.

[0071] FIG. 1A illustrates a close-up view of a joint between the operating head and the elongate shaft. Numbering is as for FIG. 1.

[0072] FIG. 2 shows a cryoprobe (1) having a shaft (2) and a distal operating head (5). The shaft is in a bent configuration, which is useful to prevent overcrowding at the insertion site when more than one device is used. The shaft has a grip region 103 of larger outer diameter than the shaft, which is covered in a heat shrink cover (155). The shaft (2) extends proximally of the grip (103) as a tail region (150). In this region, the shaft is covered by a cover extending from the grip (103) to the proximal connector (151), which is configured for connection of the first passageway to a cryofluid source (not shown). The connector also comprises the distal outlet of the second passageway via outlet (19) for venting the low-pressure gas to the atmosphere (300). The connector further comprises an inlet (301) for coupling to a source of high pressure gas.

[0073] FIG. 3 shows a section through a cryoprobe to illustrate features thereof. The cryoprobe (1) has a grip (103) that aids manipulation of the probe and acts to prevents flexing of the shaft during insertion into tissue and prevent kinking of the shaft. The cryoprobe has an elongate shaft (2) passing through and extending distally from the grip portion (103). An operating head (5) is provided distally of the elongate shaft (2). The shaft extends proximally of the grip (103) in the form of a tail portion (150), which terminates in a fitting (151) configured to connect the first passageway (3) to a cryofluid source (not shown).

[0074] The elongate shaft (2) encloses a first passageway (3) that is co-extensive with an inlet tube (17). A second passageway (4) is co-extensive with an outlet tube (18). The second passageway (4) may be open to the atmosphere proximally, e.g., via an outlet (19). The distal most end (26) of the inlet tube (17) typically projects into an expansion chamber (6) and may terminate in a Joule-Thomson orifice (7) that is formed at the distal most end (32) of the first passageway (3).

[0075] The inlet tube (17) is configured to deliver a cryogas under pressure from a cryofluid source (not shown in this figure). The cryogas expands on exiting the Joule-Thomson orifice (7) and evacuates via the outlet tube (18) to atmosphere at the opening (19).

[0076] A vacuum chamber (8) is formed over the outlet tube (18) and is bounded externally by an outer circumferential vacuum chamber wall (27). The vacuum chamber is configured to thermally insulate the shaft proximal to the operating head and so prevent tissue damage proximal to the intended ice ball.

[0077] The shaft (2) extends through the grip portion (103) and maybe continuous with the tail portion (150) as shown, or may form a union with a demountable tail portion (not shown).

[0078] The grip portion (103) has a diameter greater than the vacuum chamber wall (27) and provides a stiffened region of the shaft which prevents the shaft from flexing during manipulation and so prevents the shaft from kinking. In one arrangement, the grip portion comprises a sleeve (104) having a diameter greater than the vacuum chamber wall (27). The sleeve (104) may be of metal or polymer. In one approach, the sleeve may have tapered regions (164, 165) that provide a step down in sleeve diameter and provide a push fit over the vacuum chamber wall (27). The grip (103) may comprise a space (106) between the sleeve (104) and the vacuum chamber wall (27). The tapered regions of the sleeve (164, 165) are particularly useful in this case, particularly where the sleeve is metal as they allow a thin metallic sleeve to provide a wide grip portion with minimal weight, and provide stiffening to the sleeve. Where the space (106) is present it may be evacuated to provide additional insulation. The region between the vacuum chamber wall and the sleeve may also be filled with an insulating material.

[0079] The tail portion (150) may be provided with a covering (107), typically extending at least from the grip (103) to the proximal portion (152) of the tail (150). The covering (107) provides protection to the tail (150) and reduces kinking within the tail. The cover (107) may be loosely provided over the vacuum sleeve wall (27) within the tail region (150) or may be addressed to the vacuum sleeve wall (27). A coating (155) may be provided over the sleeve to seal the sleeve to the vacuum chamber wall (27). It may also extend to hold the distal end (154) of the cover (107) in place. This coating (155) may comprise a heat shrink sleeve, for example.

[0080] FIG. 4 illustrates a further embodiment of the grip portion. The cryoprobe (1) has a grip (103) for manipulation of the probe, and to prevent flexing of the probe during use and thereby prevent kinking of the shaft (2). The cryoprobe has an elongate shaft (2) passing through and extending distally from the grip portion (103). An operating head (5) is provided distally of the elongate shaft (2). The shaft extends proximally of the grip (103) in the form of a tail portion (150), which terminates in a fitting (151) configured to connect the first passageway (3) to a cryofluid source (not shown). The elongate shaft (2) encloses a first passageway (3) that is co-extensive with an inlet tube (17). A second passageway (4) is co-extensive with an outlet tube (18). The second passageway (4) may be open to the atmosphere proximally. The distal most end (26) of the inlet tube (17) typically projects into an expansion chamber (6) and may terminate in a Joule-Thomson orifice (7) which is formed at the distal most end (32) of the first passageway (3).

[0081] The inlet tube (17) is configured to deliver a cryogas under pressure from a cryofluid source (not shown in this figure). The cryogas expands on exiting the Joule-Thomson orifice (7) and evacuates via the outlet tube (18) to atmosphere at the distal opening (not shown in this figure).

[0082] A vacuum chamber (8) is formed over the outlet tube (18) bounded externally by an outer circumferential vacuum chamber wall (27). The vacuum chamber is configured to thermally insulate the shaft proximal to the operating head (5) and so prevent tissue damage proximal to the intended ice ball.

[0083] The shaft (2) extend through the grip portion (103) and may be continuous with the tail portion (150) as shown, or may form a union with a demountable tail portion (not shown) which provides the connection to the cryofluid source and optionally the proximal gas evacuation port(s).

[0084] The grip portion (103) has a diameter greater than the vacuum chamber wall (27) and provides a stiffened region of the shaft which prevents flexing of the shaft and protects the shaft during manipulation. In one arrangement, the grip portion (103) comprises a first sleeve (130) having an internal diameter greater than the vacuum chamber wall (27). The sleeve (130) fits over the vacuum chamber wall and provides additional stiffness to the shaft. A cylindrical cover (155) may be provided over the first sleeve and extending proximally past the proximal end (156) of the first sleeve (155) to cover at least a portion of the tail (150). Preferably, the cover (155) extends to the proximal end of the tail (not shown here).

[0085] The first sleeve (130) and the cover (155) may be held in place distally by a grip nose piece (157), typically of polymer material, such as polypropylene or PEEK, extending circumferentially about the vacuum sleeve wall (27) at the distal end (158) of the grip and configured to receive the distal most end (162) of a second sleeve (161) in a position axially outward of the first sleeve (130). This allows for wider sleeve and therefore a wider grip for easier manipulation. The grip nose piece extends circumferentially about the shaft (2), and may also extend circumferentially about the distal end (159) of the first sleeve (130) and the distal end (160) of the cover (155).

[0086] The proximal end (166) of the second sleeve (161) may be received in a similar manner by a grip tail piece (163) extending circumferentially about the vacuum sleeve wall (27) at the proximal end (164) of the grip.

[0087] The grip portion (103) may comprise a space (106) axially inwards of the second sleeve (161), which may optionally be filled with insulating material, but is preferably empty to provide a lighter grip.

[0088] An outer coating (not shown in this figure) may extend over the sleeve and optionally at least a portion of the nose piece and tail piece to provide a smooth surface to the grip. Again, a heat shrink tubing is useful in this regard.