Abstract:
Devices and methods for cooling microwave antennae and microwave hub construction are disclosed herein. The cooling system and hub can be utilized with a variety of microwave antenna types. A microwave hub is utilized to provide cooling fluids to a microwave antenna. The hub is constructed using no glue or adhesive for holding the different parts of the chambers in place. O-rings provide an increased reliability and consistency for fluid-tight seals in the hub. The various parts of the hub are form fitted and work together with the o-rings.

Description:
BACKGROUND 
       [0001]    The present invention relates generally to the field of ablation. More particularly, the present invention relates to apparatus, systems, and methods for cooling electrosurgical probes or microwave antennas. More particularly, the present invention relates to methods of assembly of electro-surgery and microwave antennas. 
         [0002]    During the course of surgical procedures, it is often necessary for medical personnel to utilize electrosurgical instruments to ablate tissue in a body. High frequency probes or antennas are often utilized to ablate tissue in a body. In use, the probes or antennas are connected to a high frequency power source to heat body tissue when inserted into the tissue. Among the drawbacks of such devices is the potential that the probes or antennas will overheat, thus causing damage to the bodily tissue or causing damage to the instrument. A cooling system may be used in conjunction with the instrument to provide cooling of the instrument and often to the tissue adjacent to the instrument so as to provide optimal thermal characteristics in the instrument and the tissue. In the event that the heat is not dissipated in the instrument, charring of the tissue or failure of the instrument can occur. 
         [0003]    Surgical systems exist that provide cooling systems for the instrument. Existing systems provide a flow of a cooling fluid to the instrument thus cooling the instrument and potentially the tissue adjacent to or abutting the targeted tissue. These systems generally employ a mechanism whereby the cooling fluid flows into a hub through a chamber. The fluid flows into a lumen path and down to the tip of the instrument, providing cooling along the shaft of the instrument. The fluid returns to another chamber in the hub and exits through a fluid egress channel. 
         [0004]    The chambers, lumen paths, hub and seals of a hub are constructed in a manner requiring an adhesive, or glue, to maintain their integrity during stress. It is known that during use, pressure is created in the interior of the hub causing stress at the seal locations, in the chambers and at the connection points. However, adhesives or glue can be inconsistent and unreliable. Not only can adhesives breakdown under stress or heat conditions, but the application of the adhesives during the manufacturing process can be inconsistent. These breakdowns and inconsistencies can lead to malfunctions and inadequate cooling. 
       SUMMARY OF THE INVENTION 
       [0005]    According to one embodiment of the present invention, there is provided an electrosurgical hub. The hub is adapted to provide cooling fluid to probes that extend from a distal end of the hub. The probes are utilized by medical personnel to ablate tissue in a body. 
         [0006]    Two chambers and a dual path lumen provide cooling liquid to a probe. Cooling fluid enters into the hub and is channeled from a first chamber through a lumen path which transports the fluid to the probes for cooling purposes. An insert defines the boundary for the first chamber and causes the cooling fluid to spin, thus reducing the presence of air bubbles. The insert is adapted to accommodate a first o-ring to form a seal between the first chamber and a second chamber. A connector connected to the probes which conducts power to the probe, is also adapted to accommodate a second o-ring to form a seal on the back side of the first chamber. 
         [0007]    The cooling fluid returns through a second lumen path and enters a second chamber. A plug is adapted to accommodate a third o-ring to form a second seal on the second chamber. The plug has an annular ring utilized to center the plug in the hub and maintain the third o-ring in position during high stress conditions. 
         [0008]    In general, the apparatus of the present invention is directed to a twin sealing chamber ablation hub constructed without glues or adhesives. The system offers a method of construction that improves reliability in the chamber seals. The apparatus includes a geometry whereby air bubbles which can cause hot spots on the ablation probe are substantially removed from the cooling liquid. 
         [0009]    There is accordingly a need for an electrosurgical hub that provides consistency in manufactured result as well as reliability under stress conditions. There is a need for a hub that overcomes the breakdown of adhesives. There is also a need for a hub that allows for consistent manufacturing procedures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a view of an embodiment of the invention showing twin chambers in a hub with inserts providing separation of the chambers; 
           [0011]      FIG. 2  is an alternate view of an embodiment of the invention showing twin chambers in a hub with inserts providing separation of the chambers; and 
           [0012]      FIG. 3  is a view of an insert of an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0013]    In one embodiment of the invention, a twin chamber microwave ablation hub comprises a plurality of inserts and o-rings causing seals between the chambers. A first chamber provides fluidic connection to an input port and a second chamber provides fluidic connection to an exit port. A dual path lumen provides fluidic connection from the first chamber to the second chamber. The first and second chambers are adapted to minimize the presence of air bubbles in a cooling fluid as the fluid travels through the input port and the first chamber, through a first path in the lumen to the distal end of an ablation probe. The cooling fluid returns via a second path in the lumen to the second chamber and exits the hub via the exit port. The first path and second path are concentric. 
         [0014]    The term “probe” is not limited to the present embodiment or depiction. Naturally, the efficacy of the present invention may be optimized by different types of devices intended to facilitate energy focalization in a body, such as electrodes, antennas or other suitable device. The term “probe” is used to include any device, mechanism or structure capable of being inserted into a body and allowing an energy source to be focalized for ablation or other medical treatment. 
         [0015]      FIG. 1  is a view of an embodiment of the invention showing a hub  10  and probe  20 . Hub  10  comprises a first chamber  30 , a second chamber  40 , a first lumen path  50 , a second lumen path  60 , a first port  70  and a second  72  port. First port  70  fluidicly couples to first chamber  30 . First chamber  30  fluidicly couples to first lumen path  50 . First lumen path  50  extends along a substantial portion of the probe  20 . The second lumen path  60  extends around and along the first lumen path  50  and fluidicly couples with the second chamber  40 . 
         [0016]    The first  30  and second  40  chambers are defined by inserts inside the hub  10 . A first insert  80  fits inside one end of hub  10 . In one embodiment, the first chamber  30  is at one end by the first insert toward the handle end of the hub  10 . The first insert  80  is positioned against stops  88 . Stops  88  provide a positioning stop on the interior walls  90  of the hub for the first insert  80 . The stops  88  provide a more precise positioning for the first insert  80  and eliminate placement guesswork. This allows for ease of insertion by providing a physical indicator of the proper insertion position. 
         [0017]    The interior walls  90  of the hub  10  may be graduated so that they are of decreasing diameter from the handle end of the hub to the stops  88 . This also allows for ease of insertion as well as precision in placement. In an embodiment of the invention, the graduation of the interior walls ceases prior to the stop  88 , creating a zone where the interior wall  90  is flat. As discussed below, the flat zone in wall  90  allows for more reliable sealing of the first chamber  30 . 
         [0018]    An o-ring  82  is positioned in space  83  of the insert first  80 . It is understood that the space  83  is a groove or other indentation in the first insert  80 . When the first insert  80  in inserted into the hub  10  to the proper depth, the o-ring  82  will contact the flat portion of the interior wall. The O-ring  82  provides for continued sealing in the event of slight movement or slight inaccuracies in the manufacture of the first insert  80  or hub  10 . The flat area allows for continued contact of the o-ring  82  in the event of slight movement. The o-ring  82  provides a water-tight seal for the first chamber  30 . Accordingly, any cooling fluid will not flow around chamber  30  and past stops  88 . 
         [0019]    The second chamber  40  is positioned distally of the first chamber  30 , toward the probe end of the hub  10 . As noted above, the first insert  80  is inserted inside the hub  10  to stops  88 . One end of the second chamber  40  is formed by the back side of the first insert  80 . The second chamber  40  is completed by second insert  95  opposite the first insert  80 . Insert  95  is inserted into the distal end of the hub  10  opposite the first insert  80 . In one embodiment, the interior walls of the hub  10  at the distal end are graduated so that they are of decreasing diameter from the end of hub  10  to the interior. The graduation of the interior walls ceases at the location where the o-ring  84  reside. This creates a flat zone which allows continued sealing in the event of slight movement or slight inaccuracies in the manufacture of the insert  95  or hub  10 . The graduation of the interior walls of hub  10  allow for ease of insertion of insert  95  as well as precision in placement. 
         [0020]    The insert  95  comprises an end portion  96  adapted to provide a stopping mechanism. The end portion  96  acts to contact the end of hub  10 . End portion  96  abuts the hub  10  and provides for precision in placement. An o-ring  84  is positioned in the second insert  95  to contact the interior wall  90  when the second insert  95  is inserted into the hub  10 . The O-ring  84  is positioned in space  98  of the second insert  95 . The o-ring  84  provides a water-tight seal for the second chamber  40 . Accordingly, cooling fluid will not flow around chamber  40  or into the first chamber  30 . The second insert  95  is molded to hub  10  on the opposite end of the hub  10  from handle  100 . The molding maintains closure and sealing during high pressure conditions. 
         [0021]    When the second insert  95  is inserted, a centered position in the hub is desired to help eliminate any leakage that may occur otherwise. An annular ring  120  is utilized to maintain a centered position of the second insert  95  and the o-ring  84  within the hub  10 . When the second insert  95  in inserted so that the end portion  96  abuts the hub  10 , the annular ring  120  contacts the interior wall  90  and disallows movement of the second insert  95 . 
         [0022]    A third o-ring  86  is positioned in handle  100 . The third o-ring  86  provides a fluid seal on the back side of chamber  30 . The handle  100  in inserted into the end of the hub  10  opposing the position of insert  95 . In an embodiment, the handle  100  is molded to hub  10 . The handle  100  is adapted to abut or closely abut insert  80 . The position of insert  80  is maintained by the handle  100  under high pressure conditions. 
         [0023]    Handle  100  connects to the probe  20 . Box  110  disallows improper insertion of the handle  100  and ensures that the microwave cable  20  is connected properly through the hub  10 . Box  110  protrudes away from the hub to disallow upside down insertion of the handle  100 . The probe  20  protrudes through the first  30  and second  40  chambers and first  80  and second  95  inserts. 
         [0024]      FIG. 2  is a perspective view of an embodiment of the invention showing hub  210  and probe  220  extending from within the handle  299  out through the distal end of the hub  210 . The probe  220  connects within the handle  299  to a power source (not shown). Hub  210  comprises a first chamber  230 , a second chamber  240 , a first lumen path  250 , a second lumen path  260  and a first  270  and second  272  port. In an embodiment, the first  270  and second  272  ports are angled in relation to the axis of the hub  210  so that they are not perpendicular to the axis. The angle of the ports  270 ,  272  forms an acute angle toward the proximal end of the hub  210 . The handle  299  forms a seal at the proximal end of the hub  210 . 
         [0025]    An insert  280  forms the first chamber  230  between the handle  299  and the insert  280 . A second insert  295  forms the second chamber  240  between the first insert  280  and the second insert  295 . The first chamber  230  is sealed by an o-ring  282  on the distal end of the chamber  230  and an o-ring  286  on the proximal end of the chamber  230 . The second chamber  240  is sealed by o-ring  282  and an o-ring  286  on the distal end of the second chamber  240 . Each O-ring  282 ,  284 ,  286  resides in a groove, or other formation, formed to receive the o-ring in the first insert  280 , the second insert  295  and the handle  299 , respectively. 
         [0026]    The first lumen path  260  forms a fluid passage allowing a cooling fluid to travel from the first chamber  230  along the probe  220  to the distal end of the probe  220 . The cooling fluid provides a cooling action along the length and tip (not shown) of the probe  220 . The second lumen path  250  provides a return passage for the cooling liquid and is fluidicly coupled to the second chamber  240 . The cooling liquid returns concentrically and outside the first lumen path  260  and empties into the second chamber  240 . 
         [0027]    As noted above relating to  FIGS. 1 and 2 , the first insert ( 80  in  FIG. 1 and 280  in  FIG. 2 ) defines a boundary for the first chamber ( 30  in  FIG. 1 and 230  in  FIG. 2 ) and causes the cooling fluid to spin and thus reduce the presence of air bubbles.  FIG. 3  provides a detailed view of the first insert  280 . As noted above, the first insert  280  creates the first chamber ( 230   FIG. 2 ). The insert  280  creates the chamber by using a seal  310  in the hub ( 210   FIG. 2 ). In an embodiment, the seal  310  is an o-ring which fits in a grooved portion  320 , or other formed recess, of the insert. The grooved portion  320  is adapted to accommodate the o-ring  310 . 
         [0028]    Cooling fluid flows into the first chamber and fills the space within the insert  280 . The geometry  325  on the insert  280  is concave and induces spin in the cooling fluid as it enters the first chamber. The vortex type action induced on the cooling fluid allows it to move around the probe as it moves down the first lumen path. The vortex action aids in the elimination of air bubbles which may cause overheating of the probe. 
         [0029]    The insert  280  comprises a plurality of legs  330 . In one embodiment, four legs  330  provide support for the insert  280 . The legs  330  provide a mechanism to abut the handle (not shown in  FIG. 3 ) when the hub (not shown in  FIG. 3 ) is assembled. The legs  330  will push against the handle to force the insert  280  against the stops on the interior of the hub. 
         [0030]    Referring again to  FIG. 1 , regarding the operation of the invention. Cooling fluid flows into the first port  70  and fills the first chamber  30 . In one embodiment, the first chamber  30  is sized so that it fills with fluid relatively rapidly. The first insert  80  is shaped so that the fluid entering the first chamber  30  spins in a circular manner. The spinning of the fluid causes any residual air bubbles to be removed from the probe  20  and the walls of the first chamber  30 . Air bubbles are known in the art to cause over-heating of the probe  20  and lead to failure of the device. The o-ring  82  in the first insert  30  seals the chamber  30 , thus not allowing fluid to enter the second chamber  40 . It is understood by those skilled in the art that the first insert  30  provides sealing. The o-ring  82  provides an extra level of sealing to ensure integrity under pressure conditions. 
         [0031]    The handle  10  has the O-ring  86  to create a seal on the back side of the first chamber  30 . It is understood by those skilled in the art that the handle  10  provides a level of sealing. The o-ring  86  provides an extra level of sealing to ensure integrity under pressure conditions. The cooling fluid flows out of chamber  30  and through the first lumen path  50 . The first lumen path  50  carries the cooling fluid to the proximal end of the probe  20  providing a cooling effect on the probe  20 . The cooling fluid returns to the hub  10  via the second lumen path  60 . The cooling fluid empties from the second lumen path  60  into the second chamber  40 . The second chamber is sealed by the o-ring  82  on one end which is positioned in the first insert  80  and the o-ring  84  which is positioned in the second insert  95 . It is understood by those skilled in the art that the second insert  95  provides a level of sealing. The o-ring  84  provides and extra level of sealing to ensure integrity under pressure conditions. 
         [0032]    As the cooling fluid pressure increases in the hub  10 , the pressure will cause a separating force on the components within the hub  10 . This pressure will stress the position of the o-ring  82  in the first insert  80  and the o-ring  84  of the second insert  95 . An external geometry (not shown) positioned on the outside of the handle  100  will hold the handle  100  in place and resist movement of the inserts  80 ,  95  and o-rings  82 ,  84 . 
         [0033]    Referring again to  FIG. 2 , the microwave assembly is easily manufactured with the hub  210 , the first insert  280 , the second insert  295  and the handle  299 . The first insert  280  is inserted into the hub  210  until it abuts the stops  288  which are formed on the inside of the hub  210 . The o-ring  282  in the first insert provides a seal against the interior wall of hub  210 . In an embodiment, the wall of the hub  210  is graduated so that the circumference lessens toward the middle of the hub  210 . The graduation levels off and ceases as the wall nears the stop  288  to allow a location for the o-ring  282  to seal. 
         [0034]    The interior lumen path  260  connects to the central hole  292  in the first insert  280 . The lumen paths  250 ,  260  protrude through the end of the hub  210 . The second insert  295  is inserted over the lumen paths  250 ,  260  and into the distal end of the hub  210 . O-ring  286  fits in a groove around the second insert  295  and forms a seal against the interior wall of the hub  210 . In one embodiment, the wall at the distal end of the hub  210  is also graduated so that the circumference lessens toward the middle of the hub  210 . The graduation levels off and ceases at a predetermined location which coincides with the position of the o-ring  286 . The second insert  295  is molded to the distal end of the hub  210  to provide stability during high pressure situations. 
         [0035]    The handle  299  and the probes are inserted into the proximal end of the hub  210 . The probe  220  passes through the central holes in the inserts  280 ,  295  and helps create and enforce the lumen paths  250 ,  260 . In an embodiment the handle  299  and probes  220  are pre-assembled to maintain a sound electrical connection. A lip portion  298  extends from the portion of the hub  210  opposite the ports  270 ,  272 . The lip portion  298  allows the insertion of the handle  299  in only one way to assure proper insertion of the handle  299 . Insertion of the handle  299  provides sufficient pressure on the first insert  280  to maintain the insert  280  in the proper position. The stop  288  on the interior of the hub  210  wall prevents the first insert from being inserted too far inside the hub  210 . The handle  299  is then molded to the hub  210 . 
         [0036]    It is understood that the above described embodiments are only illustrative of the application of the principles of the present disclosure. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of the present disclosure. The appended claims are intended to cover such modifications and arrangements.