Abstract:
Improved devices, systems and methods for treating a tissue region provide straightforward, yet reliable ways for installing diverse functional components within the confined space of a catheter-based instrument.

Description:
RELATED APPLICATIONS 
       [0001]    This application is a divisional of co-pending U.S. application Ser. No. 10/760, 433, filed Jan. 20, 2004, which is a divisional of U.S. application Ser. No. 09/955,915, filed Sep. 19, 2001, entitled “Devices, Systems and Methods for Treating Tissue Regions of the Body” (now U.S. Pat. No. 6,699,243). 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention is directed to devices, systems and methods for treating tissue regions of the body. 
       BACKGROUND OF THE INVENTION 
       [0003]    Catheter based instruments are widely used to gain access to interior body regions for diagnostic or therapeutic purposes. The size of such instruments are constrained by the need to permit deployment and use within relatively small, confined areas of the body. Still, there is the need for such instruments to carry one or more functional components, e.g., to ablate body tissue and/or to convey fluid into contact with tissue in the targeted tissue region and/or to sense local tissue conditions, etc. 
         [0004]    The challenge persists in accommodating the need for small, easily deployed catheter-based instruments with the demand for reliable and robust functionality. 
       SUMMARY OF THE INVENTION 
       [0005]    The invention provides improved devices, systems and methods for treating a tissue region that provide straightforward, yet reliable ways for installing diverse functional components within the confined space of a catheter-based instrument. 
         [0006]    One aspect of the invention provides a support assembly for an elongated electrode element. The support assembly comprises at least one spine for holding the elongated electrode element for use. The spine peripherally defines at least one spine lumen. The support assembly also includes an insert carried by the spine. The insert peripherally defines an insert lumen sized to accommodate forward and rearward sliding movement of the elongated electrode element within the spine. The insert includes a distal extension having an outer dimension sized for insertion into the spine lumen. The insert also includes a proximal region having an outer dimension sized to resist insertion into the spine lumen, to thereby define a maximum insertion length for the distal extension into the spine lumen. 
         [0007]    In one embodiment, the spine includes a side opening, and the distal extension of the insert includes an open distal end. In this arrangement, the maximum insertion length places the open distal end in desired alignment with the side opening for guiding sliding movement of a distal portion of the elongated electrode element toward the side opening. 
         [0008]    In one embodiment, the spine includes an interior ramp that depends from the side opening. In this arrangement, the maximum insertion length locates the open distal end of the insert on the interior ramp for guiding sliding movement of a distal portion of the elongated electrode element toward the side opening. 
         [0009]    In one embodiment, the maximum insertion length keeps the distal end of the insert from projecting through the side opening. 
         [0010]    Another aspect of the invention provides an electrode assembly. The assembly comprises an elongated electrode element having a distal operative portion. A connector to couple the elongated electrode element to a source of radio frequency energy. The assembly also mounts the elongated electrode element for sliding movement within an insert in a spine, as previously described. 
         [0011]    Another aspect of the invention provides a method for making a support assembly for an elongated electrode element. The method provides at least one spine with a lumen for holding the elongated electrode element for use. The method forms a side opening in the spine in communication with the spine lumen. The method also provides an insert for the spine lumen. The insert peripherally defines an insert lumen sized to accommodate forward and rearward sliding movement of the elongated electrode element within the spine. The insert includes a distal extension having an outer dimension sized for insertion into the spine lumen. The insert also includes a proximal region having an outer dimension sized to resist insertion into the spine lumen. 
         [0012]    The method inserts the distal extension through the spine lumen and outward beyond the side opening until the proximal region resists further insertion. The method cuts the distal extension flush with the side opening to form an open distal end. The cutting also defines a maximum insertion length for the distal extension. 
         [0013]    In one embodiment, the method secures the proximal region of the insert to the spine. 
         [0014]    In one embodiment, after performing the cutting step, the method moves the proximal region of the insert a short distance from the spine to withdraw the open distal end into the spine lumen. Afterwards, the method can secure the proximal region of the insert to the spine. 
         [0015]    In one embodiment, the method forms an interior ramp that depends from the side opening. In this arrangement, the distal extension is inserted through the spine lumen and outward beyond the side opening along the interior ramp. 
         [0016]    In one arrangement, after performing the cutting step, the method moves the proximal region a short distance from the spine to withdraw the open distal end into the spine lumen to rest on the interior ramp. Afterward, the method can secure the proximal region of the insert to the spine. 
         [0017]    Another aspect of the invention provides systems and methods for handling fluid to or from an operative element carried by a catheter tube. The systems and methods provide a manifold body sized to fit within the catheter tube. The manifold body includes a single main fluid junction, multiple branch fluid junctions, and a fluid circuit formed within the manifold body to channel fluid flow between the single main fluid junction and the multiple branch fluid junctions. The systems and methods couple the single main fluid junction to a fluid source or a fluid destination external to the catheter tube. The systems and methods couple each of the multiple branch fluid junctions individually to a fluid-conveying port on the operative element. The systems and methods mount the manifold within the catheter tube. 
         [0018]    Features and advantages of the inventions are set forth in the following Description and Drawings, as well as in the appended Claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a schematic view of a system for treating tissue that includes a treatment device that embodies features of the invention; 
           [0020]      FIG. 2  is a perspective view, with portions broken away and in section, of the treatment device shown in  FIG. 1 , with the basket element carried by the device shown in a collapsed condition for deployment to a targeted tissue region; 
           [0021]      FIG. 3  is a perspective view, with portions broken away, of the treatment device shown in  FIG. 1 , with the basket element carried by the device shown in an expanded condition, as it would be when ready for use in a targeted tissue region; 
           [0022]      FIG. 4  is a perspective view, with portions broken away, of the treatment device shown in  FIG. 1 , with the basket element carried by the device shown in an expanded condition, and with electrodes carried by the basket element extended for use in a targeted tissue region; 
           [0023]      FIG. 5  is an enlarged end view of one of the multiple lumen spines that form the basket element shown in  FIGS. 2 to 4 , showing the multiple interior lumens that the spine possesses; 
           [0024]      FIG. 6  is a top view of the multiple lumen spine shown in  FIG. 5 , showing the different functional elements that the interior lumens of the spine carry; 
           [0025]      FIG. 7  is a schematic view of the interior of the catheter tube and handle of the treatment device shown in  FIGS. 2 to 4 , showing the routing of different functional elements within the confined space of the catheter tube; 
           [0026]      FIG. 8  is an enlarged view of a portion of one of the multiple lumen spines that form the basket element shown in  FIGS. 2 to 4 , showing an electrode deployed through an opening in one of the spines; 
           [0027]      FIG. 9  is a side view of the electrode shown in  FIG. 8 , out of association with the spine; 
           [0028]      FIG. 10  is a side section view of the lumen of the spine shown in  FIG. 5 , in which the electrode shown in  FIG. 9  is carried, showing an insert that guides passage of the electrode within the spine, and showing the electrode in an extended position for use; 
           [0029]      FIGS. 11 to 15  are side sectional views showing the assembly of the insert shown in  FIG. 10  into the spine; 
           [0030]      FIG. 16  is a side section view of the lumen of the spine shown in  FIG. 10 , showing the electrode in a retracted position within the insert; 
           [0031]      FIG. 17  is a perspective view of an irrigation manifold that the treatment device shown in  FIG. 1  possesses, to route fluid within the catheter tube from a single source to several basket spines; 
           [0032]      FIG. 18  is a distal end view of the irrigation manifold shown in  FIG. 17 ; 
           [0033]      FIG. 19  is a proximal end view of the irrigation manifold shown in  FIG. 17 ; 
           [0034]      FIG. 20  is a side section view of the irrigation manifold shown in  FIG. 17  taken generally along line  20 - 20  in  FIG. 19 ; and 
           [0035]      FIG. 21  is a schematic view of the irrigation manifold shown in  FIG. 17  positioned within the catheter tube of the treatment device shown on  FIG. 1 , and serving to channel fluid from a source simultaneously to several basket spines. 
       
    
    
       [0036]    The invention may be embodied in several forms without departing from its spirit or essential characteristics. The scope of the invention is defined in the appended claims, rather than in the specific description preceding them. All embodiments that fall within the meaning and range of equivalency of the claims are therefore intended to be embraced by the claims. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    This Specification discloses various catheter-based systems and methods for treating dysfunction in various locations in an animal body. For example, the various aspects of the invention have application in procedures requiring treatment of sphincters and adjoining tissue regions in the body, or hemorrhoids, or incontinence, or restoring compliance to or otherwise tightening interior tissue or muscle regions. The systems and methods that embody features of the invention are also adaptable for use with systems and surgical techniques that are not necessarily catheter-based. 
         [0038]    The systems and methods are particularly well suited for treating dysfunctions in the upper gastrointestinal tract, e.g., in the lower esophageal sphincter and adjacent cardia of the stomach. For this reason, the systems and methods will be described in this context. Still, it should be appreciated that the disclosed systems and methods are applicable for use in treating other dysfunctions elsewhere in the body, which are not necessarily sphincter-related. 
       I. Overview 
       [0039]    A tissue treatment device  26  is shown in  FIG. 1 . The device  26  includes a handle  28  made, e.g., from molded plastic. The handle  28  carries a flexible catheter tube  30 . The catheter tube  30  can be constructed, for example, using standard flexible, medical grade plastic materials, like vinyl, nylon, poly(ethylene), ionomer, poly(urethane), poly(amide), and poly(ethylene terephthalate). The handle  28  is sized to be conveniently held by a physician, to introduce the catheter tube  30  into the tissue region targeted for treatment. The catheter tube  30  may be deployed with or without the use of a guide wire (not shown). 
         [0040]    The catheter tube  30  carries on its distal end an operative element  36 . The operative element  36  can take different forms and can be used for either therapeutic purposes, or diagnostic purposes, or both. The operative element  36  can support, for example, a device for imaging body tissue, such as an endoscope, or an ultrasound transducer. The operative element  36  can also support a device to deliver a drug or therapeutic material to body tissue. The operative element  36  can also support a device for sensing a physiological characteristic in tissue, such as electrical activity, or for transmitting energy to stimulate tissue or to form lesions in tissue. 
         [0041]    In the illustrated embodiment (shown in greater detail in  FIGS. 2 ,  3 , and  4 ), one function that the operative element  36  performs is to apply energy in a selective fashion to a targeted tissue region. For the purpose of illustration, the targeted tissue region can comprise, for example, the lower esophageal sphincter, or cardia of the stomach, or both. The applied energy creates one or more lesions, or a prescribed pattern of lesions, below the mucosal surface of the esophagus or cardia. The subsurface lesions are formed in a manner that preserves and protects the mucosal surface against thermal damage. The natural healing of the subsurface lesions leads to a physical tightening of the sphincter and/or adjoining cardia. The subsurface lesions can also result in the interruption of aberrant electrical pathways that may cause spontaneous sphincter relaxation. In any event, the treatment can restore normal closure function to the sphincter. 
         [0042]    In this arrangement (as  FIG. 1  shows), the treatment device  26  can operate as part of a system  24 . The system  24  includes a generator  38  to supply the treatment energy to the operative element  36 . 
         [0043]    A cable  40  is coupled to the handle  28 . The cable  40  is electrically coupled to the operative element  36  by wires that extend through the catheter tube  30 . The cable  40  is also electrically coupled to the generator  38 , to convey the generated energy to the operative element  36 . 
         [0044]    In the illustrated embodiment, the generator  38  supplies radio frequency energy, e.g., having a frequency in the range of about 400 kHz to about 10 mHz. Of course, other forms of energy can be applied, e.g., coherent or incoherent light; heated or cooled fluid; resistive heating; microwave; ultrasound; a tissue ablation fluid; or cryogenic fluid. 
         [0045]    The system  24  can also include certain auxiliary processing equipment. In the illustrated embodiment, the processing equipment comprises an external fluid delivery or irrigation apparatus  44 . A luer fitting  48  on the handle  28  couples to tubing  34  to connect the treatment device  26  to the fluid delivery apparatus  44 , to convey processing fluid for discharge by or near the operative element  36 . 
         [0046]    The system  24  also desirably includes a controller  52 . The controller  52  is linked to the generator  38  and the fluid delivery apparatus  44 . The controller  52 , which preferably includes an onboard central processing unit, governs the power levels, cycles, and duration that the radio frequency energy is distributed to the operative element  36 , to achieve and maintain power levels appropriate to achieve the desired treatment objectives. In tandem, the controller  52  also desirably governs the delivery of processing fluid. 
         [0047]    The controller  52  desirably includes an input/output (I/O) device  54 . The I/O device  54  allows the physician to input control and processing variables, to enable the controller to generate appropriate command signals. 
       II. The Operative Element 
       [0048]    In the embodiment shown in  FIGS. 2 to 4 , the operative element  36  comprises a three-dimensional basket  56 . The basket  56  includes one or more spines  58 , and typically includes from four to eight spines  58 , which are assembled together by a distal hub  60  and a proximal base  62 . In  FIGS. 2 to 4 , four spines  58  are shown, which are equally circumferentially spaced apart. 
         [0049]    Each spine  58  preferably comprises a flexible body made, e.g. from molded plastic, stainless steel, or nickel titanium alloy. Candidate plastic materials for the spine  58  include PEEK, Ultem, polyimide, Pebax, Hytrel polyester, PET, and polyurethane. 
         [0050]    The cross sectional shape of the spine body  58  can vary, possessing, e.g., a circular, elliptical, square, or rectilinear shape. In the illustrated embodiment, the spine bodies  58  each possess a rectilinear shape to resist twisting. 
         [0051]    In the illustrated embodiment (see  FIG. 5 ), each spine body  58  defines two or more interior lumens or passages. As  FIG. 5  shows, in the illustrated embodiment, three lumens or passages, designated L 1 , L 2 , and L 3 , are present. For each spine  58 , each passage L 1 , L 2 , and L 3  is dedicated to accommodate a different functional element. 
         [0052]    In the illustrated embodiment (see  FIGS. 6 and 7 ), a first or center passage L 1  carries a movable, elongated electrode element  66 . A second passage L 2  along one side the first passage L 1  carries a temperature sensing element  80 . A third passage L 3  along the opposite side of first passage L 1  is coupled to tubing  82  that carries processing fluid from the fluid delivery device  44 . 
         [0053]    A. The Electrodes 
         [0054]    Each electrode  66  is carried within the first passage L 1  for sliding movement. Each electrode  66  slides from a retracted position, withdrawn in the spine  58  (as shown in  FIG. 3 ), and an extended position, extending outward from the spine  58  through an opening  84  in the spine  58  (as shown in  FIGS. 4 and 8 ). 
         [0055]    As  FIG. 7  best shows, a push-pull lever  68  on the handle  28  (as  FIGS. 2 to 4  also show) is coupled by a stylet  86  to a carrier  88  located within the catheter tube  30 . The electrodes  66  are secured to the carrier  88 , extending from the carrier  88  into the lumens L 1  of the respective spine  58 . The lever  68  controls the sliding movement of the electrodes with the spines  58  between the retracted position (by pulling rearward on the lever  68 , arrow  90  in  FIG. 7 ) and the extended position (by pushing forward on the lever  68 , arrow  92  in  FIG. 7 ). 
         [0056]    As  FIGS. 2 to 4  show, the lever  68  is exposed on the handle  28  for manipulation by the thumb of an operator. A suitable rachet assembly  118  (see  FIG. 2 ) may be provided to advance the sliding movement of the lever  68  in a controlled, stepwise fashion. A slot  119  on the handle  28  stops advancement of the lever  68  beyond a predetermined distance. 
         [0057]    In the illustrated arrangement, the electrodes  66  are intended for monopolar operation. Each electrode  66  serves as a transmitter of energy, and an indifferent patch electrode on the patient=s skin (not shown) serves as a common return for all electrodes  66 . It should be appreciated, however, the operative element  36  could include bipolar pairs of electrodes  66 , if desired. 
         [0058]    In the embodiment shown in  FIGS. 2 to 4 , an expandable structure  72  comprising, e.g., a balloon, is located within the basket  56 . The balloon structure  72  can be made, e.g., from a Polyethylene Terephthalate (PET) material, or a polyamide (non-compliant) material, or a radiation cross-linked polyethylene (semi-compliant) material, or a latex material, or a silicone material, or a C-Flex (highly compliant) material. Non-compliant materials offer the advantages of a predictable size and pressure feedback when inflated in contact with tissue. Compliant materials offer the advantages of variable sizes and shape conformance to adjacent tissue geometries. 
         [0059]    The balloon structure  72  presents a normally, generally collapsed condition, as  FIG. 2  shows. In this condition, the basket  56  is also normally collapsed about the balloon structure  72 , presenting a low profile for deployment into the targeted tissue region. 
         [0060]    The catheter tube  30  includes an interior lumen  94  (see  FIG. 3 ), which communicates with the interior of the balloon structure  72 . A fitting  76  (e.g., a syringe-activated check valve) is carried by the handle  28 . The fitting  76  communicates with the lumen. The fitting  76  couples the lumen  94  to a syringe  78  (see  FIG. 3 ), which injects fluid under pressure through the lumen  94  into the balloon structure  72 , causing its expansion, as  FIG. 3  shows. 
         [0061]    Expansion of the balloon structure  72  urges the spines  58  of the basket  56  to open and expand (as  FIG. 3  shows). The force exerted by the balloon structure  72  upon the spines  58 , when expanded, is sufficient to exert an opening force upon the tissue surrounding the basket  56 . When moved to their extended positions, the electrode  66  penetrate tissue contacted by the spines  58 . 
         [0062]    The electrodes  66  can be formed from various energy transmitting materials. For deployment in the esophagus or cardia of the stomach, the electrodes  66  are formed, e.g., from nickel titanium. The electrodes  66  can also be formed from stainless steel, e.g., 304 stainless steel, or, as will be described later, a combination of nickel titanium and stainless steel. The electrodes  66  have sufficient distal sharpness and strength to penetrate a desired depth into the smooth muscle of the esophageal or cardia wall. The desired depth can range from about 4 mm to about 5 mm. 
         [0063]    To further facilitate penetration and anchoring in the targeted tissue region, each electrode  66  is preferably biased with a bend (as  FIGS. 4 and 8  show). Movement of the electrode  66  into the spine  58  overcomes the bias and straightens the electrode  66  for passage through the lumen L 1 . 
         [0064]    In the illustrated embodiment (see  FIGS. 4 and 8 ), each electrode  66  is normally biased with an antegrade bend (i.e., bending toward the proximal base  62  of the basket  56 ). Alternatively, each electrode  66  can be normally biased toward an opposite retrograde bend (i.e., bending toward the distal hub  60  of the basket  58 ). 
         [0065]    An electrical insulating material  70  (see  FIG. 9 ) is desirably coated about the distal end of each electrode  66 , a distance below the distal tip. For deployment in the esophagus or cardia, the length of the insulating material  70  ranges from about 80 to about 120 mm. The insulating material can comprise, e.g., a Polyethylene Terephthalate (PET) material, or a polyimide or polyamide material. For deployment in the esophagus or cardia, each electrode  66  preferably presents an exposed, non-insulated conductive length of about 8 mm. When the distal end of the electrode  66  that penetrates the targeted tissue region transmits radio frequency energy, the material  70  insulates the surface of the tissue region from direct exposure to the radio frequency energy. 
         [0066]    Desirably (see  FIG. 10 ), the electrode  66  slides within an insert  96  positioned within the first passage L 1 . The insert  96  guides the electrode  66  to the electrode opening  84  and protects the spine  58  from inadvertent puncture or Apoke-through® by the electrode  66 . 
         [0067]    The insert  96  is preferably made of a relatively hard (i.e., high durometer) and tough plastic material, e.g., PEEK plastic. This plastic material has a durometer in excess of 75 Shore D. The hardness provides lubricity for easy electrode movement within the insert  96 , and the toughness makes the insert  96  resistant to puncture by the electrode  66 . The insert material desirably is also adhesively bondable, which PEEK plastic is. Desirably, the insert is also reformable with heat, which PEEK plastic is, so that its outer diameter can be readily altered in desired ways during manufacture, as will be described in greater detail below. 
         [0068]    Other candidate materials for the insert  96  include Ultem, polyimide, Pebax, Hytrel polyester, PET, and polyurethane. 
         [0069]    A main advantage of the insert  96  is absolute guidance of the electrode  66  through the spine opening  84 . The flexibility to provide an insert  96  of a different material and possessing different mechanical properties than a spine  58  is another advantage. The insert  96  can also have a different wall thickness than the spine body  58 , so that the dimensions of each of these components can be made appropriate to the function they perform. 
         [0070]    As  FIG. 10  shows, the insert  96  includes a first body portion  98  and a second body portion  100 . The first body portion  96  has an outside diameter smaller than the inner diameter of the passage L 1 , to accommodate insertion of the first body portion  98  into the passage L 1 . The second body portion  100  has an outside diameter that is larger than the inner diameter of the passage L 1 , to prevent its insertion into the passage. The transition between the first and second body portions  98  and  100  forms a notch  102  that abuts against the proximal end  116  of the spine  58 . This abutment forms a mechanical stop, to prevent movement of the first body portion  98  within the passage L 1  beyond a prescribed distance. 
         [0071]    In this arrangement (see  FIG. 9 ), the electrode  66  may comprise a hybrid of materials comprising stainless steel for the proximal portion  104  and nickel titanium alloy for the distal portion  106 . The nickel titanium alloy performs best in the curved distal portion  106  of the electrode  66 , due to its super-elastic properties. The use of stainless steel in the proximal portion  104  can reduce cost, by minimizing the amount of nickel titanium alloy required. 
         [0072]    The different materials may be joined, e.g., by crimping, swaging, soldering, welding, or adhesive bonding, which provide electrical continuity between or among the various materials. 
         [0073]    The distal portion  106  of the electrode  66  possesses an outside diameter less than the inner diameter of the insert  96 . This allows the distal portion  106  of the electrode  66  to freely slide within the insert  96 . The proximal portion  104  of the electrode has an outside diameter that is larger than the inner diameter of the insert  96 . The transition between the distal and proximal portions  106  and  104  of the electrode  66  forms a notch  108  that abuts against the notch  102  formed at the transition between the first and second body portions  98  and  100  of the insert  96 . 
         [0074]    In assembly (see  FIG. 11 ), the electrode opening  84  is formed in the spine  58  by a heat gun  112  or the like in the desired located on the exterior of the passage L 1 . As  FIG. 12  shows, a segment  110  of the spine wall is displaced into the passage L 1  as the opening  84  is created. This wall segment  110  is deflected into the passage L 1 , to form an interior ramp appended to the opening  84 . 
         [0075]    As  FIG. 13  shows, the first body portion  98  of the insert  96  is inserted through the proximal end  116  of the spine  58  into the passage L 1 . The first body portion  98  is advanced through the formed opening  84  to the fullest extent permitted, i.e., until the notch  102  between the first and second body portions  98  and  100  abuts against the proximal end  116  of the spine  58 . 
         [0076]    As  FIG. 14  shows, the first body portion  98  that projects from the opening  84  is cut to form a terminus  112  that is flush with the opening  84 . The insert  96  is then pulled back a small distance (see  FIG. 15 ), so that the terminus  112  rests within the passage L 1  against the ramp wall segment  110 , a small distance below the plane of the opening  84 . Adhesive  114  is applied in the space between the notch  102  and the proximal end  116  of the spine  58 , to thereby secure the insert  96  to the body of the spine  58 . As  FIG. 16  shows, the distal portion  106  of the electrode  66  freely slides through the insert  96  in response to operation of the push-pull lever  68  previously described. The insert terminus  112  faces toward the opening  84 , and serves to reliably guide the distal portion  106  of the electrode  66  toward and away from the opening  84 . The eventual abutment between the lever  68  and the slot  119  on the handle  28  (see  FIG. 2 ) will mechanically stop further passage of the distal portion  106  of the electrode  66  through the opening  84 . The depth of electrode penetration into tissue is thus mechanically controlled, to prevent puncture through the targeted tissue region. 
         [0077]    Should the adhesive  114  fail, the eventual abutment of the notch  102  (between the first and second body portions  98  and  100  of the insert  96 ) against the proximal end  116  of the spine  58  will mechanically limit the extent to which the insert terminus  112  can advance through the opening  84 . The mechanically limited displacement of the insert terminus  112  through the opening  84  serves to prevent exposure of the cut insert. terminus  112  beyond the plane of the electrode opening and into contact with tissue. 
         [0078]    The electrodes  66  can be formed in various sizes and shapes. The electrodes  66  can possess a circular cross sectional shape. However, the electrodes  66  preferably possess a cross section that provides increased resistance to twisting or bending as the electrodes penetrate tissue. For example, the electrodes can possess a rectangular cross section. Alternatively, the electrodes  66  can possess an elliptical cross section. Other cross sections, e.g., conical or pyramidal, can also be used to resist twisting. 
         [0079]    The surface of the electrode  66  can, e.g., be smooth, or textured, or concave, or convex. The preceding description describes electrodes  66  bent in either an antegrade or retrograde direction over an arc of ninety degrees or less. The bend provides a secure anchorage in tissue. Retraction of the electrodes  66  into the insert overcomes the bias and straightens the electrode  66  when not in use. 
         [0080]    B. Surface Cooling 
         [0081]    In the illustrated embodiment (see  FIG. 6 ), the fluid delivery apparatus  44  conveys processing fluid through the third passage L 3  in the spine  58  for discharge at the treatment site. The processing fluid F can comprise, e.g., saline or sterile water, to cool surface tissue while energy is being applied by the electrode  66  to ohmically heat muscle or tissue beneath the surface, to thereby protect the surface tissue from thermal damage. 
         [0082]    The third passage L 3  conveys liquid from the irrigation apparatus through an opening  120  formed in the spine  58 . The irrigation opening  120  in each spine  58  is generally aligned with the needle opening  84  in the spine  58 , so that ablation and cooling occur in the same general tissue region. 
         [0083]    In the illustrated embodiment (see  FIG. 7 ), the individual lengths of tubing  82  that convey irrigation fluid to each passage L 3  of the spines  58  are coupled to an irrigation manifold  122  within the catheter tube  30 . The irrigation manifold  122  is, in turn, coupled by a single tube  124  to the luer fitting  48  on the handle  28 , previously described (see  FIG. 1 ). The irrigation manifold  122  simplifies connection of the multiple tubing  82  to the single tube  124  within the confined space of the catheter tube  30  (as  FIG. 21  shows), as well as efficiently routes cooling fluid to the appropriate openings  120 . 
         [0084]    The irrigation manifold  122  can be constructed in various ways, e.g., from molded or machined plastic such as polycarbonate or Ultem. In the illustrated embodiment (see  FIGS. 17 to 20 ), the manifold  122  is formed from plastic to form a compact body  134  sized to fit within the catheter tube. The manifold body including a single main fluid junction or inlet port  130 , multiple branch fluid junctions or apertures  128 , and a fluid circuit  126  formed within the manifold body  134  to channel fluid flow between the single main fluid junction  130  and the multiple branch fluid junctions  128 . The single tube  124  is secured to the main fluid junction  130  (see  FIG. 21 ), e.g., by an adhesive bond. The multiple branch fluid junctions or apertures  128 , which are sized and arranged side-by-side to receive individual ends of the tubings  82  (see  FIG. 21 ), e.g., by adhesive bonds. The apertures  128  desirably include internal tubing stops to facilitate accurate adhesive bonding. The manifold  122  is also desirably made from a clear or transparent plastic, to further facilitate the process of adhesive bonding the tubings  82  within the apertures  128 . The tubings  82  extend from the manifold  122  and are routed to the designated passages L 3  in the spines  58 . The cavity  126  distributes irrigation fluid conveyed through the single tube  124  to the individual tubings  82  serving the spines  58 . 
         [0085]    In a representative embodiment, the manifold body  134  can measure about 0.74 inch in overall maximum length (from apertures  128  to the end of the inlet port  130 ) and about 0.274 inch in maximum width. 
         [0086]    It should be appreciated that the manifold  122  can serve to handle fluid flow either to (i.e, fluid irrigation) or from (i.e., fluid aspiration) an operative element carried by a catheter tube. The manifold body for carrying out either function is sized to fit within the catheter tube. The manifold body is machined or molded as a single unit to including a single main fluid junction (inlet  130 ), multiple branch fluid junctions (apertures  128 ), and a fluid circuit (circuit  126 ) to channel fluid flow between the single main fluid junction and the multiple branch fluid junctions. The single main fluid junction can be coupled either to a fluid source or a fluid destination external to the catheter tube. Likewise, each of the multiple branch fluid junctions can be individually coupled to a fluid-conveying port on the operative element. 
       C. Temperature Sensing 
       [0087]    In the illustrated embodiment (see  FIGS. 6 and 7 ), the second passage L 2  in each spine  58  carries a temperature sensing element  80 . In the illustrated embodiment, the temperature sensing element  80  comprises a thermocouple assembly. The temperature sensor is exposed through an opening  140  in the spine body  38 . The temperature sensor rests against surface tissue when the basket structure is deployed for use. Desirably (as  FIG. 6  shows), the temperature sensor opening  140  is generally aligned with the electrode and cooling fluid openings  84  and  120 , so that ablation, temperature sensing, and cooling occur generally in the same localized tissue region. 
         [0088]    As  FIG. 7  shows, the individual thermocouple wires  80  extend from the respective passages L 2 . The thermocouple wires  80  are desirably wound to form a composite thermocouple cable  142 . The thermocouple cable  142  extends through the catheter tube  30  into the handle  28 . The thermocouple cable  142  is electrically coupled (via the cable  40 ) to temperature sensing and processing elements of the controller  52 . 
         [0089]    The I/O device  54  of the controller  52  receives real time processing feedback information from the temperature sensors  80 , for processing by the controller  52 , e.g., to govern the application of energy and the delivery of processing fluid. The I/O device  54  can also include a graphical user interface (GUI), to graphically present processing information to the physician for viewing or analysis. 
         [0090]    Various features of the invention are set forth in the following claim.