Abstract:
The invention proposes a cryoprobe for surgical and other treatments. The cryoprobe comprises a bellow-wise section that performs displacement of a distal cryotip forwards with elevation of operation pressure in the interior of the cryoprobe. Needle-wise metal elements are installed on the external side of the cryotip. These needle-wise elements are deflecting outwards by a deflecting member fastened on the distal edge of an external shaft of the cryoprobe. This allows to enlarge significantly a frozen volume of the treated tissue for same operation temperature and the outer diameter of the cryoprobe.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is directed to providing a cryogenic probe for medical applications, such as surgery. 
         [0003]    2. Summary Of the Prior Art 
         [0004]    Cryogenic technology provides cooling to very low temperatures. It is widely used in medicine, and particularly in surgery. Freezing tissue can kill its cells, and this makes cryosurgery particularly useful for treating cancerous growths. A cryogenic-probe may be used to kill the cells of malignant cysts in mammary tissue. The cryoprobe is required to have a small diameter to cause minimal damage and trauma to the body tissue in its passage through body tissue. 
         [0005]    Typically, the site requiring treatment is significantly larger than the diameter of the cryoprobe and is all too frequently wider than the effectively frozen volume of tissue that is treatable by a single probe insertion. Use of multiple probes causes additional trauma and discomfort. Indeed, it will be appreciated that resorting to such procedures will invariably cause trauma to a large volume of tissue contacted along the entire length of the cryogenic probe used to bring the probe tip to its destination. 
         [0006]    One interesting development that addresses the issue of treating a considerably larger volume of tissue than that in proximity to the shaft of the ablation needle is described in U.S. Pat. No. 7,025,767 to Schaefer et a., titled “Tumor ablation needle with independently activated and independently traversing tines” which relates to a tumor ablation needle for use to treat ablated tumors with RF energy. The tumor ablation needle described therein comprises a needle with a spreading array of individually traversing conductive tines that are independently positioned. Specifically, An ablation probe, comprising: an elongated member having an exterior wall, a proximal end, and a distal end; a plurality of electrical insulators extending through the elongated member, each of the insulators having a lumen, wherein the elongated member has apertures extending along the exterior wall into each of the electrical insulators; a plurality of elongated electrode tines extending through the respective insulator lumens; and a plurality of side members associated with the proximal end of the elongated member, the side members mechanically connected to the respective electrode tines through the respective apertures for being operable to independently move the respective electrode tines to extend beyond, or retract within, the distal end of the elongated member, is discussed. 
         [0007]    There are some US patents teaching designs of cryosurgical probes or catheters with variable shapes of their distal tips. These include U.S. Pat. Nos. 7,001,378, 6,954,977, 6,951,569, 6,942,659, 6,913,604, 6,995,493. Such patents can be divided into three categories:
       1. Cryocatheters with inflatable cryotips.   2. Cryoprobes or cryocatheters with tubular spiral-wise cryotips.   3. Cryoprobes with linearly extending cryotips.       
 
         [0011]    US Patent application No. 20050177147 describes a cryoablation system which includes an elongated tubular cannula having a proximal end, a distal end, and a longitudinal axis, an expandable balloon extending from the distal end of the cannula and fluidly connected to a source of heat transfer fluid by at least one fluid path, a pump for circulating the heat transfer fluid into and out of the balloon, a probe handle coupled to the proximal end of the cannula and in fluidic communication with the balloon through the cannula, and a heat exchanger for varying the temperature of the heat transfer fluid, wherein the heat exchanger is fluidly connected to a secondary refrigerant source. The balloon is preferably expandable in response to an addition of a volume of heat transfer fluid. The heat exchanger may be positioned within the probe handle so that the secondary refrigerant can cool the heat transfer fluid to a treatment temperature before the heat transfer fluid is provided to the balloon, or the heat exchanger may alternatively be positioned within the console of the system so that the secondary refrigerant can cool the heat transfer fluid to a treatment temperature before the fluid is provided to the probe handle, or the heat exchanger may alternatively be positioned within the cannula so that the secondary refrigerant can cool the heat transfer fluid to a treatment temperature before the heat transfer fluid is provided to the balloon. In another alternative, the heat exchanger is positioned at least partially within the balloon. 
         [0012]    However, there is no design of a cryoprobe or cryocatheter, which allows to enlarge significantly an ice ball formed around the cryotip without inflating this cryotip and without substantial increase of the effective diameter of the cryotip. 
         [0013]    There is a need for a narrow cryogenic probe that can treat a relatively large volume of tissue, and the present invention addresses this need. 
       SUMMARY OF THE INVENTION  
       [0014]    In a first aspect, the present invention is directed to providing a cryogenic probe for coupling via a cryogenic conduit to a cryogenic cooling system. The cryogenic probe comprises three concentric lumen: an outer lumen ending in a perforated tip having at least one aperture there through and an inner deflecting member; an intermediate lumen that terminates at distal end thereof in a closed bellows arrangement to which a needle array is coupled, and is sealingly connected at proximal section thereof to the outer lumen; and an inner lumen that is open ended and serves to bring a cryogen into close proximity with the distal end of the intermediate lumen; such that boiling and expansion of the cryogen in the inner lumen causes the bellows arrangement to expand, forward with displacement of the needle arrangement forwards towards the perforated tip, such that deflecting member deflects at least one flexible needle of the needle array, sideways and outwards through at least one aperture, to protrude outwards from the distal end of the cryogenic probe. 
         [0015]    The cryogenic probe may be used for medical applications such that displacement the needle array forwards by expansion of the bellows causes at least one needle to be deflected by the deflecting member and to protrude outwards from the outer lumen, allowing treatment of tissue in a larger volume. 
         [0016]    In preferred embodiments, the needle array comprises a plurality of flexible needles arranged in a regular polygon array, said at least one aperture comprises a plurality of apertures such that displacement of the needle array forwards in the cylinder causes the plurality of flexible needles to splay, by them being deflected sideways and outwards through the at least one aperture to protrude outwards from the distal end of the cryogenic probe. 
         [0017]    Typically, the plurality of flexible needles comprises needles that are identical with each other. 
         [0018]    Optionally, at least one flexible needle is a solid needle; the proximal end thereof being cryogenically cooled, thereby cooling the distal end thereof by thermal conduction. 
         [0019]    Alternatively, at least one flexible needle is a hollow needle having an open proximal end and a closed distal end; the hollow needle being cryogenically cooled by a cryogen therein. Preferably, the inner surface of such a hollow needle is at least partially coated with an open-pore porous metal coating. 
         [0020]    The outer lumen is preferably characterized by at least one of the following list of restrictions: (i) a high rigidity and (ii) a thermal insulation means. 
         [0021]    The deflecting member is preferably characterized by at least one of the following list of restrictions: (a) the deflecting member is fabricated at least partially from a metal having a high thermal conductivity coefficient; (b) an inner surface of the deflecting member having a shape suitable for smoothly deflecting at least one flexible needle. 
         [0022]    Optionally the bellows head further comprises an internal porous coating having open pore porosity providing a surface for boiling cryogen thereupon. 
         [0023]    Optionally, the inner lumen is a cryogenic conduit that includes an expansion orifice at distal end thereof to allow a high pressure cryogenic gas to expand into the intermediate lumen and to partially liquefy. 
         [0024]    Optionally, the cryogenic cooling system uses a liquid cryogen. 
         [0025]    Optionally, the cryogenic probe tip further comprises an additional needle extending coaxially from the distal end of the bellows head on the intermediate lumen; the deflecting member having an axial hole there through to allow passage of the additional needle. 
     
     
       BRIEF DESCRIPTION OF THE FIGURES  
         [0026]    For a better understanding of the invention and to show how it may be carried into effect, reference will now be made, purely by way of example, to the accompanying drawings. 
           [0027]    With specific reference now to the drawings in detail, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the preferred embodiments of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention; the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 
           [0028]    In the accompanying drawings: 
           [0029]      FIG. 1  is a schematic cross section through a cryogenic probe in accordance with a first embodiment of the present invention having solid needles, in its retracted position; 
           [0030]      FIG. 2  is a schematic cross section through the cryogenic probe of  FIG. 1  in its extended position with extended needles; 
           [0031]      FIG. 3  is a schematic cross section through a cryogenic probe in accordance with a second embodiment of the present invention; 
           [0032]      FIG. 4  is a schematic cross section through a cryogenic probe in accordance with a third embodiment of the present invention; 
           [0033]      FIG. 5  is a schematic cross section through a cryogenic probe in in accordance with a fourth embodiment of the present invention having hollow needles. 
           [0034]      FIG. 6  is a schematic cross section through a cryogenic probe having a single needle probe that extends sideways out of the cylinder when it is displaced forwards by the bellows thereof. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0035]    The present invention relates to novel cryogenic probes that are useful for a variety of medical applications, particularly surgical techniques such as cryoablation. 
         [0036]    Such probes are useful for treating cysts and cancerous growths and, to be directed to a desired location, have to pass through healthy body tissue or through body cavities, and, to minimize trauma to healthy tissue, should be as narrow as possible. To effectively treat a cancerous growth, the volume of cryogenically frozen tissue should include all the cancerous cells. Thus it is desired that the effective diameter of the active part of the probe tip should be large. These are competing requirements. 
         [0037]    The volume treatable by a single insertion of a single, acceptably narrow probe of the prior art may be insufficient to treat the full volume of tissue requiring treatment. The present invention provides a extendible probe tip, that is preferable configurable to extend sideways as necessary, between fully extended and fully retracted limits. 
         [0038]    With reference to  FIG. 1 , a cryogenic probe  100  in accordance with a first embodiment of the present invention is shown. The crypogenic probe  100  is coupled to a cryogenic freezing system (not shown) via connector  110  that serves as an inlet for cryogenic fluid. 
         [0039]    A vent conduit  102  and an outlet connection  111  which serve for venting the gaseous phase of the cryogenic fluid after use is also provided. 
         [0040]    The cryogenic probe  100  includes an intermediate lumen  102  that terminates in bellow  103 , Bellows  103  are sealed at the distal edge thereof by a face plane  105  to the outer side of which a needle array  106  is appended, such that needle array points forwards, parrallel to axis of the intermediate lumen. Due to the bellows arrangement  103 ; the needle array  106  may be displaced frontwards and backwards, thereby extended and retracted via openings in cryoprobe tip. The intermediate lumen  102  is coupled to an external lumen  101  at distal end thereof. The external lumen  101  preferably has a high rigidity and is provided with a thermal insulation means. By displacement of bellows  103 , the bellows head  105  and the needle array  106  can be displaced-between a retracted position shown in  FIG. 1 , and an extended position as shown in  FIG. 2 . 
         [0041]    At the distal end of the external lumen  101 , a blunt tip  107  is provided, having a deflecting member  112  on inner surface thereof. The needle array  106  comprises one or more needles. Needles  106  extend forwards from the intermediate lumen  102  in a direction substantially parallel to the axis of the intermediate lumen  102 , such that if the bellows  103  are expanded, needles  106  are displaced forwards and are deflected sideways and outwards by the deflecting member  112  of blunt tip  107 , through apertures  108  set in the wall of the outer lumen  101  at the join between the outer lumen  101  and the blunt tip  107 . This results in the needle(s)  106  protruding outwards from the distal end of probe  1   00 , and assuming the extended position shown in  FIG. 2 . In this manner the needle(s)  106  can provide a cryogenic freezing effect in body tissue situated a larger distance away from tip  107  and the probe shaft, i.e. the outer lumen  101  This increases the effective diameter of the probe  100 . 
         [0042]    Where, as shown in  FIG. 1 , a plurality of such needles is arranged in parallel in an array of a regular polygon; circumferentially on the bellow&#39;s face plane  105 ; extension of bellows  103  within the outer lumen  101  results in the needles  105  being splayed out outwards, thereby allowing a cryogenic treatment to be effected over a relatively large volume, having a diameter that is much larger than the effective diameter that can be treated by a conventional cryogenic probe, it being appreciated that the probe  100  is designed for insertion into the body, and should, to minimise damage to tissue during its insertion and removal, be as narrow as possible. 
         [0043]    The cryogenic conduit may usefully include an an inner lumen  104  that is terminated at its distal end by connector  110  such that cryogenic fluid entering probe  100  via connector  110  is conveyed down inner lumen  104  to the distal end of the inner lumen  104  to allow a cryogenic fluid to boil on the inner surface of the face plane  105  that is provided with a porous coating  109  with open porosity so that the cryogenic fluid coolingly expands at distal end of the inner lumen  104  within bellows  103 , thereby both: displacing face plane  105  forwards and providing a cryogenic freezing effect at the distal end of the probe  100 , such that the expansion of the cryogenic gas occurs close to the needle array  106 . It should be noted, that a counter-flow heat exchanger, which is requided in this case, is not shown in the drawing. 
         [0044]    Typically the flexible needles  106  are all identical, but need not be. In the embodiment of  FIG. 1 and 2 , the face plane  105  is displacing forwards and the proximal ends of needles  106  are cooled by thermal conductivity from this face plane. 
         [0045]    Typically the flexible needles  106  are all identical, but need not be. In the embodiment of  FIG. 1  the face plane  105  is-displaced from the retracted position to the extended position by bellows  103 , illustrated as being situated right behind the face plane  105  and needle array- 106  attached thereto. Expansion of the bellows  103  displaces needles  106  forwards, onto the deflecting member  112 , and contraction of bellow  103  displaces the face plane  105  backwards retracting needles  106  attached thereto, providing the probe tip  100  with a small diameter, allowing it to be retracted from the body with minimal difficulty. 
         [0046]    The blunt tip  107  of probe  100  is preferably fabricated from a metal having a high thermal conductivity coefficient such as silver, for example. The deflecting member  112  on the inner surface thereof has a shape suitable for smoothly deflecting the flexible needle(s)  106  such as a cone or spherical shape, for example. The inner surface of the face plane  105  may be coated with a porous coating  109  having an open porosity to provide a large surface to encourage cryogenic fluid to boil thereon, providing the cryogenic freezing effect. 
         [0047]      FIG. 2  shows the axial section of the cryoprobe with the expandable cryotip in its operation state (where the internal pressure in the internal space of the cryoprobe is significantly higher than the atmospheric pressure). The cryogenic probe  200  comprises three tubular elements: an external shaft  201  with relatively high rigidity, an intervening lumen  202  with a bellows section  203  and a central feeding lumen  204  for delivery of a cryogen. 
         [0048]    The needle-wise elements  206  are installed on the outer surface of a face plane  205 , which seals the distal section of the intervening lumen  202 . 
         [0049]    The distal end of the external shaft is closed by a face plane element  207 , having a pointed outer surface and an inner surface with a deflecting form. In addition, the distal section of the external shaft  201  is provided with openings  208  for enabling the needle-wise elements  206  to protrude. 
         [0050]    The internal surface of the face plane  205  is coated by a porous metal coating  209  with open porosity. 
         [0051]    In addition, the proximal end of the central feeding lumen  204  is provided with a pipe connection  210 . 
         [0052]    In some embodiments, such as that shown in  FIGS. 1 and 2 , the flexible needle(s)  106  are solid and the proximal end(s) thereof are directly cryogenically cooled, with the distal end(s) thereof being cooled by thermal conduction therealong. 
         [0053]    Referring now to  FIG. 3 , in a second embodiment, mutatis mutandis, the cryogenic probe  300  may additionally include an additional extending needle-wise element  309  and a central hole  308  in the deflecting member  307 . The cryoprobe comprises three tubular elements: an external shaft  301  with relatively high rigidity, an intervening lumen  302  with a bellows section  303  and a central feeding lumen  304  for delivery of a cryogen. The peripheral needle-wise elements  306  are installed on the outer side of a face plane  305 , which seals the distal section of the intervening lumen  302 . The distal end of the external shaft is closed by the deflecting member  307 , which is pointed at its surface faced outwards and its surface directed inwards has a deflecting form. There is a central needle wise element  309 , which is installed on the outer side of the face plane  305  and positioned in the abovementioned central opening  308  with possibility of protruding from this central opening  308  with change of pressure in the internal space of the intervening lumen  302 . In addition, the distal section of the external shaft is provided with openings  310  for protruding the peripheral needle-wise elements  306 . The internal surface of the face plane  305  is coated by a porous metal coating  311  with open porosity. The proximal end of the central lumen  304  is provided with an inlet connection  312 , and an outlet connection  313  serves for removal of gases from the cryoprobe  300 . 
         [0054]    Referring to  FIG. 4 , in a third embodiment, mutatis mutandis, the flexible needle(s)  407  of probe  400  are sealed hollow needle(s) having closed proximal end(s) and closed distal end(s), the needles serving as heat pipe(s), i.e. they are filled with a cryogenic liquid, and its vapors; their counter-flow in the internal space of the needle allowing effective heat transfer from the proximal section of each needle to its distal section. 
         [0055]    The cryoprobe comprises three tubular elements: an external shaft  401  with relatively high rigidity, an intervening lumen  402  with a bellows section  403  and a central feeding lumen  404  with the inlet connection  405  for delivery of a cryogen. The proximal edge of the intervening lumen  402  is sealed with the proximal section of the central feeding lumen  404 , and the proximal edge of the external shaft  401  is sealed with the proximal section of the intervening lumen  402 . The distal section of the external shaft  401  is provided with opening  410  allowing to protrude needles  407  therethrough. A deflecting member  409  serves for deflecting the needle-wise elements  407  outwards in the process of their displacement forwards. 
         [0056]    The proximal section of the intervening lumen  402  is provided with the outlet connection  406  for removal of gases from the internal space of this intervening lumen  402 . The needle-wise elements  407  are installed as shown. 
         [0057]    As shown in  FIG. 5 , in a further embodiment, the enlarged axial section of the distal part of a cryoprobe with the needle-wise elements constructed as open heat pipes. Each needle-wise element  506  is constructed as a heat pipe; the internal walls of this heat pipe is provided with a porous coating  510 . The internal surface of the face plane  507  is coated by a porous metal coating  511  with open porosity. The internal spaces of the needle-wise elements  506  is in fluid communication with the internal space of the intervening lumen  502 , and the porous metal coatings  510  of these needle-wise elements are in capillary communication with the porous coating  511  of the face plane  507 . In such a way, the needle-wise elements  506  are functioning as heat pipes, when the cryogen is delivered via the central feeding lumen  504  on the porous metal coating  511 . Again, the needles  510  are displaced to the deflecting member  507  when they are displaced forwards by bellows  503 . 
         [0058]    In various embodiments, the cryogenic probe may be coupled to a cryogenic cooling system that uses a liquid cryogen such as liquid nitrous oxide, liquid argon or liquid nitrogen, or a gaseous cryogen, such as pressurized gaseous argon or nitrous oxide, for example. 
         [0059]    In various embodiments, the cryogenic probe may be coupled to a cryogenic cooling system that uses a liquid cryogen such as liquid nitrous oxide, liquid argon or liquid nitrogen, or a highly pressurized gaseous cryogen which should be expended via an orifice installed on the distal end of the central feeding lumen with its partial liquefying. In the last case, the distal section of the cryoprobe is provided with a counte-flow heat exchanger. 
         [0060]    As shown in  FIG. 6 , in a variant, providing some of the functionality of the embodiments described hereinabove, probe  600  has only one needle  607  provided at the distal end of a face plane  608 . The face plane  608  is joined sealingly with bellow  603  and a deflecting member is shaped to deflect needle  620  through an apperture  610  to protrude sideways from shaft  601  of probe  600 . 
         [0061]    Cryoprobe  600  comprises three tubular elements: the external shaft  601  with relatively high rigidity, an intervening lumen  602  with the bellows section  603  and a central feeding lumen  604  with the inlet connection  605  for delivery of a cryogen. The proximal edge of the intervening lumen  602  is sealed with the proximal section of the central feeding lumen  604 , and proximal edge of the external shaft  601  is sealed with the proximal section of the intervening lumen  602 . 
         [0062]    The proximal section of the intervening lumen  602  is provided with the outlet connection  606  for removal of gases from the internal space of this intervening lumen. The central needle-wise element  607  is constructed as an open capillary heat pipe; the internal wall of this capillary heat pipe is provided with a porous coating  611 . 
         [0063]    The internal surface of the face plane  608  is coated with a porous metal coating  612  with open porosity. 
         [0064]    The internal spaces of the central needle-wise element  607  is in fluid communication with the internal space of the intervening lumen  602 , and the porous metal coating  612  of the central needle-wise element is in capillary communication with the porous coating  611  of the face plane  607 . 
         [0065]    In this manner, the needle-wise element  607  functions as an open heat pipe, when the cryogen is delivered via the central feeding lumen  604  on the porous metal coating  611 . 
         [0066]    The cryogenic probes of the present invention may be used in a wide range of surgical applications including, inter alia, to treat cancerous growths, for treating breast cancer, for liver surgery, gynecology, and brainsurgery. 
         [0067]    Persons skilled in the art will appreciate that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined by the appended claims and includes both combinations and sub combinations of the various features described hereinabove as well as variations and modifications thereof, which would occur to persons skilled in the art upon reading the foregoing description. 
         [0068]    In the claims, the word “comprise”, and variations thereof such as “comprises”, “comprising” and the like indicate that the components listed are included, but not generally to the exclusion of other components.