Abstract:
A dual function catheter handle is provided for simultaneous movement of two control wires. The catheter handle has a handle housing having proximal and distal ends and a generally hollow interior. A core is mounted in the interior of the handle housing, the core having a longitudinal slot therethrough. A first moveable member is provided with a proximal end mounted in the interior of the handle housing and a distal end extending outside the handle housing. The first moveable member is longitudinally moveable relative to the handle housing. A second moveable member is mounted in the longitudinal slot of the core and is longitudinally moveable relative to the core and handle housing. The second moveable member has a threaded surface. A rotatable member is mounted on the handle housing. The rotatable member has a threaded inner surface that mates with the threaded surface of the second moveable member so that rotation of the rotatable member causes longitudinal movement of the second moveable member. The first moveable member and second moveable member are capable of simultaneously moving proximally relative to the handle housing.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
   This application is a continuation of U.S. patent application Ser. No. 10/040,981, filed Dec. 31, 2001 now U.S. Pat. No. 6,913,594, entitled DUAL-FUNCTION CATHETER HANDLE, the entire disclosures of which are incorporated herein by reference. 

   FIELD OF THE INVENTION 
   The present invention is directed to a dual-function catheter handle for manipulating two different control wires. 
   BACKGROUND OF THE INVENTION 
   Electrode catheters have been in common use in medical practice for many years. They are used to stimulate and map electrical activity in the heart and to ablate sites of aberrant electrical activity. 
   In use, the electrode catheter is inserted into a major vein or artery, e.g., femoral artery, and then guided into the chamber of the heart which is of concern. Within the heart, the ability to control the exact position and orientation of the catheter tip is critical and largely determines how useful the catheter is. 
   Steerable catheters are generally well-known. For example, U.S. Patent No. RE 34,502 describes a catheter having a control handle comprising a housing having a piston chamber at its distal end. A piston is mounted in the piston chamber and is afforded lengthwise movement. The proximal end of the catheter body is attached to the piston. A puller wire is attached to the housing and extends through the piston and through the catheter body. The distal end of the puller wire is anchored in the tip section of the catheter. In this arrangement, lengthwise movement of the piston relative to the housing results in deflection of the distal end of the catheter body. The design described in RE 34,502 is generally limited to a catheter having a single puller wire. 
   Some catheter designs require more than one puller wire. For example, if a bidirectional catheter is desired, i.e., a catheter that can be deflected in more than one direction without rotating the catheter body, more than one puller wire becomes necessary. Catheters having two or more puller wires and handles for controlling the multiple puller wires are disclosed, for example, in U.S. Pat. Nos. 6,171,277 and 6,183,463. However, these patents describe catheter handles whereby simultaneous proximal movement of the puller wires relative to the catheter body is prohibited, which is desirable for certain applications. However, for other applications, it is desirable to simultaneously move the puller wires proximally relative to the catheter body. 
   SUMMARY OF THE INVENTION 
   The present invention is directed to a dual function catheter handle that is capable of simultaneously moving two control or puller wires relative to the body of the catheter and also to a catheter incorporating the handle. In one embodiment, the invention is directed to a catheter handle comprising a handle housing having proximal and distal ends and a generally hollow interior. A first moveable member is provided having a proximal end mounted in the interior of the handle housing and a distal end extending outside the handle housing. The first moveable member is longitudinally moveable relative to the handle housing. A second moveable member is mounted in the interior of the handle housing and longitudinally moveable relative to the handle housing. A rotatable member is mounted on the handle housing so that rotation of the rotatable member causes longitudinal movement of the second moveable member. 
   In a particularly preferred embodiment, the invention is directed to a catheter handle comprising a handle housing having proximal and distal ends and a generally hollow interior. A core is mounted in the interior of the handle housing, the core having a longitudinal slot therethrough. A first moveable member is provided having a proximal end mounted in the interior of the handle housing and a distal end extending outside the handle housing. The first moveable member is longitudinally moveable relative to the handle housing. A second moveable member is mounted in the longitudinal slot of the core and is longitudinally moveable relative to the core and handle housing. The second moveable member has a threaded surface. A rotatable member is mounted on the handle housing and has a threaded inner surface that mates with the threaded surface of the second moveable member. Rotation of the rotatable member causes longitudinal movement of the second moveable member. 
   In another embodiment, the invention is directed to a catheter incorporating the inventive handle. The catheter comprises an elongated, flexible catheter body having proximal and distal ends and a lumen extending therethrough. An intermediate section is mounted at the distal end of the catheter body. The intermediate section has proximal and distal ends and first and second off-axis lumens extending therethrough. The intermediate section can be separate from or integral with the catheter body. A handle as described above is mounted at the proximal end of the catheter body. The catheter body is attached to the handle housing, either directly or indirectly, for example, by mounting it to the core. A first puller wire extends through the catheter body and first off-axis lumen of the intermediate section. The first puller wire has a proximal end anchored to the first moveable member of the handle and a distal end anchored at or near the distal end of the catheter. The distal end of the catheter to which the puller wires are anchored can include any part of the distal end that is inserted into the heart, such as the intermediate section or another ablation or mapping assembly that is mounted onto the intermediate section. A second puller wire extends through the catheter body and second off-axis lumen of the intermediate section. The second puller wire has a proximal end anchored to the second moveable member of the handle and a distal end anchored at or near the distal end of the catheter. In a particularly preferred embodiment, the distal end of the first puller wire is anchored to the intermediate section and the catheter further comprises a generally circular mapping assembly mounted on distal end of the intermediate section, wherein the distal end of the second puller wire extends through an off-axis lumen of them mapping assembly and is anchored at or near the distal end of the mapping assembly for contraction of the mapping assembly. 

   
     DESCRIPTION OF THE DRAWINGS 
     These and other features and advantages of the present invention will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
       FIG. 1  is a perspective view of a catheter according to the invention. 
       FIG. 2  is a side cross-sectional view of the catheter body of a catheter according to the invention. 
       FIG. 3  is a side cross-sectional view of the junction of the intermediate section and mapping assembly of a catheter according to the invention. 
       FIG. 4  is a schematic perspective view of the mapping assembly according to the invention. 
       FIG. 5  is a side view of the mapping assembly according to the invention in a clockwise formation. 
       FIG. 6  is a side view of the mapping assembly according to the invention in a counterclockwise formation rotated 90° relative to the assembly depicted in  FIG. 5 . 
       FIG. 7  is a schematic view of the mapping assembly according to the invention. 
       FIG. 8  is a schematic view of the mapping assembly according to the invention depicting the relationship between the first and last electrodes. 
       FIG. 9  is a side section view of a catheter handle according to the invention. 
       FIG. 10  is a cut away view of the catheter handle of  FIG. 9 . 
       FIG. 11  is a perspective view of an assembly of the catheter handle of  FIG. 9 . 
       FIG. 12  is a perspective view of the piston of the catheter handle of  FIG. 9 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The invention is directed to a catheter handle for manipulating two independently displaceable control or puller wires.  FIG. 1  shows a catheter  10  comprising an elongated catheter body  12  having proximal and distal ends, a control handle  16  attached at the proximal end of the catheter body, an intermediate section  14  attached at the distal end of the catheter body, and a mapping assembly  17  attached to the intermediate section. 
   With reference to  FIG. 2 , the catheter body  12  comprises an elongated tubular construction having a single, axial or central lumen  18 , although multiple lumens can be provided if desired. The catheter body  12  is flexible, i.e., bendable, but substantially non-compressible along its length. The catheter body  12  can be of any suitable construction and made of any suitable material. A presently preferred construction comprises an outer wall  20  made of polyurethane or PEBAX. The outer wall  20  comprises an imbedded braided mesh of stainless steel or the like to increase torsional stiffness of the catheter body  12  so that, when the control handle  16  is rotated, the intermediate section  14  of the catheter  10  will rotate in a corresponding manner. 
   The outer diameter of the catheter body  12  is not critical, but is preferably no more than about 8 french, more preferably about 7 french. Likewise the thickness of the outer wall  20  is not critical, but is thin enough so that the central lumen  18  can accommodate a puller wire, lead wires, and any other desired wires, cables or tubes, as discussed in more detail below. If desired, the inner surface of the outer wall  20  may be lined with a stiffening tube (not shown) to provide improved torsional stability. A particularly preferred catheter has an outer wall  20  with an outer diameter of from about 0.090 inch to about 0.94 inch and an inner diameter of from about 0.061 inch to about 0.065 inch. 
   As shown in  FIGS. 2 and 3 , the intermediate section  14  comprises a short section of tubing  22  having three off-axis lumens, a first lumen  30  that carries a first puller wire  64 , a second lumen  32  that carries a second puller wire  65  and a third lumen  34  that carries electrode lead wires  50  and a support member  24  for the mapping assembly  17 , all of which are discussed further below. The tubing  22  is made of a suitable non-toxic material that is preferably more flexible than the catheter body  12 . A presently preferred material for the tubing  22  is braided polyurethane, i.e., polyurethane with an embedded mesh of braided stainless steel or the like. The size of each lumen is not critical, but is sufficient to house the lead wires, puller wire or support member. 
   The useful length of the catheter, i.e., that portion that can be inserted into the patient excluding the mapping assembly  17 , can vary as desired. Preferably the useful length ranges from about 110 cm to about 120 cm. The length of the intermediate section  14  is a relatively small portion of the useful length, and preferably ranges from about 3.5 cm to about 10 cm, more preferably from about 5 cm to about 6.5 cm. 
   A preferred means for attaching the catheter body  12  to the intermediate section  14  is illustrated in  FIG. 2 . The proximal end of the intermediate section  14  comprises an outer circumferential notch  26  that receives the inner surface of the outer wall  22  of the catheter body  12 . The intermediate section  14  and catheter body  12  are attached by glue or the like. 
   Alternatively, the catheter body  12  and intermediate section  14  can be formed of a single unitary piece of tubing. Such a design would be useful, for example, where the catheter body and intermediate section have the same number of lumens. 
   If desired, a spacer (not shown) can be located within the catheter body  12  between the distal end of the stiffening tube (if provided) and the proximal end of the intermediate section  14 . The spacer provides a transition in flexibility at the junction of the catheter body  12  and intermediate section  14 , which allows this junction to bend smoothly without folding or kinking. A catheter having such a spacer is described in U.S. Pat. No. 5,964,757, the disclosure of which is incorporated herein by reference. 
   At the distal end of the intermediate section  14  is a mapping assembly, as shown in  FIGS. 3 to 7 . The mapping assembly comprises a non-conductive covering  28  having two off-axis lumens  114  and  116  extending therethrough. The distal end of the support member  24 , which gives shape to the mapping assembly  17 , extends through the first lumen  114  of the non-conductive covering  28 . However, if desired, the support member  24  can be eliminated and the non-conductive covering  28  can be designed to provide the desired shape for the mapping assembly  17 . 
   The mapping assembly  17  has a generally straight proximal region  38 , a generally circular main region  39  and a generally straight distal region  40 . The proximal region  38  is mounted on the intermediate section  14 , as described in more detail below, so that its axis is generally parallel to the axis of the intermediate section. The proximal region  38  preferably has an exposed length, e.g., not contained within the intermediate section  14 , ranging from about 3 mm to about 12 mm, more preferably about 3 mm to about 8 mm, still more preferably about 5 mm inch, but can vary as desired. 
   The generally circular main region  39  does not form a flat circle, but is very slightly helical, as shown in  FIGS. 4 to 6 . The main region  39  has an outer diameter preferably ranging from about 8 mm to about 35 mm, more preferably from about 12 mm to about 20 mm, still more preferably about 15 mm. The transition region  41  of the straight proximal region  38  and generally circular main region  39  is slightly curved and formed such that, when viewed from the side with the proximal region at the top of the circular main region as shown in  FIG. 5 , the proximal region (along with the intermediate section  14 ) forms an angle α with the curved region ranging from about 75° to about 95°, preferably from about 83° to about 93°, more preferably about 87°. The main region  39  can curve in a clockwise direction, as shown in  FIG. 5 , or a counterclockwise direction, as shown in  FIG. 6 . When the assembly  17  is turned 90°, as shown in  FIG. 6 , so that the transition region  41  is near the center of the main region, the proximal region (along with the intermediate section  14 ) forms an angle β with the main region ranging from about 90° to about 135°, preferably from about 100° to about 110°, more preferably about 105°. The support member  24  is made of a material having shape-memory, i.e., that can be straightened or bent out of its original shape upon exertion of a force and is capable of substantially returning to its original shape upon removal of the force. A particularly preferred material for the support member  24  is a nickel/titanium alloy. Such alloys typically comprise about 55% nickel and 45% titanium, but may comprise from about 54% to about 57% nickel with the balance being titanium. A preferred nickel/titanium alloy is Nitinol, which has excellent shape memory, together with ductility, strength, corrosion resistance, electrical resistivity and temperature stability. The non-conductive covering  28  can be made of any suitable material, and is preferably made of a biocompatible plastic such as polyurethane or PEBAX. 
   A series of ring electrodes  36  are mounted on the non-conductive covering  28  of the generally circular main region  39  of the mapping assembly  17 . The ring electrodes  36  can be made of any suitable solid conductive material, such as platinum or gold, preferably a combination of platinum and iridium, and mounted onto the non-conductive covering  28  with glue or the like. Alternatively, the ring electrodes can be formed by coating the non-conductive covering  28  with an electrically conducting material, like platinum, gold and/or iridium. The coating can be applied using sputtering, ion beam deposition or an equivalent technique. 
   In a preferred embodiment, each ring electrode  36  is mounted by first forming a hole in the non-conductive covering  28 . An electrode lead wire  50  is fed through the hole, and the ring electrode  36  is welded in place over the lead wire and non-conductive covering  28 . The lead wires  50  extend between the non-conductive covering  28  and the support member  24 . 
   The number of ring electrodes  36  on the assembly can vary as desired. Preferably the number of ring electrodes ranges from about six to about twenty, more preferably from about eight to about twelve. In a particularly preferred embodiment, the assembly carries ten ring electrodes. The ring electrodes  36  are preferably approximately evenly spaced around the generally circular main region  39 , as best shown in  FIG. 7 . In a particularly preferred embodiment, a distance of approximately 5 mm is provided between the centers of the ring electrodes  36 . 
     FIGS. 7 and 8  show a particularly preferred electrode arrangement. As explained above, the generally circular main region  39  is very slightly helical, although  FIGS. 7 and 8  depict the main region as a flat circle, as it would generally appear when viewed from the distal end of the catheter. The generally straight distal region  40  forms a tangent relative to the generally circular main region  39  and contacts the main region at a tangent point  43 . A first electrode  36   a  is provided, which is the electrode that is on the generally circular main region  39  closest to the proximal region  38 . A second electrode  36   b  is provided, which is the electrode that is on the generally circular main region  39  closest to the distal region  40 . Preferably, the first electrode  36   a  is positioned along the circumference of the generally circular main region  39  at a distance θ of no more than about 55° from the tangent point, more preferably no more than about 48° from the tangent point, still more preferably from about 15° to about 36° from the tangent point. Preferably the second electrode  36   b  is positioned along the circumference of the generally circular main region  39  at a distance ω of no more than about 55° degrees from the tangent point, more preferably no more than about 48° from the tangent point, still more preferably from about 15° to about 36° from the tangent point. Preferably the first electrode  36   a  is positioned along the circumference of the generally circular main region  39  at a distance γ of no more than 100° from the second electrode  36   b , preferably no more than 80° from the second electrode, still more preferably from about 30° to about 75° from the second electrode. If desired, additional electrodes (not shown) could be mounted along the intermediate section  14 , the generally straight proximal section  39 , the transition region  41 , and/or generally straight distal region  40 . 
   The junction of the intermediate section  14  and mapping assembly  17  is shown in  FIG. 3 . The non-conductive covering  28  is attached to the tubing  22  of the intermediate section by glue or the like. The support member  24  extends from the third lumen  34  into the first lumen  114  of the non-conductive covering  28  and through the generally circular main region  39  of the mapping assembly. The proximal end of the support member  24  terminates a short distance within the third lumen  34  of the intermediate section  14 , approximately about 5 mm, so as not to adversely affect the ability of the intermediate section to deflect. However, if desired, the proximal end of the support member  24  can extend into the catheter body  12 . 
   The lead wires  50  attached to the ring electrodes  36  also extend through the first lumen  114  in the non-conductive covering  28 , the third lumen  34  of the intermediate section  14 , the central lumen  18  of the catheter body  12 , and the control handle  16 , and terminate at their proximal end in the connector  37 , which is connected to a source of RF energy (not shown). The portion of the lead wires  50  extending through the central lumen  18  of the catheter body  12 , control handle  16  and proximal end of the intermediate section  14  are enclosed within a protective sheath  62 , which can be made of any suitable material, preferably polyimide. The protective sheath  62  is anchored at its distal end to the proximal end of the intermediate section  14  by gluing it in the third lumen  34  with polyurethane glue or the like. 
   The generally straight distal region  40  of the mapping assembly  17  is provided with an atraumatic design to prevent the distal end of the mapping assembly from penetrating tissue. In the depicted embodiment, the distal region  40  comprises a tightly wound coil spring  44  made, for example, of stainless steel, such as the mini guidewire commercially available from Cordis Corporation (Miami, Fla.) or a coil having a 0.0045 inch wire size and a 0.009 inch inner diameter, such as that commercially available from Microspring. The coil spring  44  extends through the first lumen  114  of the non-conductive covering  28  and is mounted at its proximal end in a short piece of tubing  45  with polyurethane glue or the like, which is then glued or otherwise anchored within the non-conductive covering. The tubing  45  is less flexible than the non-conductive covering  28  but more flexible than that support member  24  to provide a transition in flexibility along the length of the mapping assembly  17 . The distal end of the distal region  40  is capped, preferably with polyurethane glue  46 , to prevent body fluids from entering the mapping assembly  17 . In the depicted embodiment, the generally straight distal region  40  has a length of about 0.5 inch, but can be any desired length, for example, ranging from about 0.25 inch to about 1.0 inch. The generally straight distal region  40  is preferably sufficiently long to serve as an anchor for introducing the catheter into a guiding sheath, as discussed in more detail below, because the mapping assembly  17  must be straightened upon introduction into the sheath. Without having the generally straight distal region  40  as an anchor, the mapping assembly  17  has a tendency to pull out of the guiding sheath upon its introduction into the guiding sheath. Additionally, if desired, the distal region  40  can be formed, at least in part, of a radiopaque material to aid in the positioning of the mapping assembly  17  under fluoroscopy. 
   As noted above, two puller wires  64  and  65  extend through the catheter. The first puller wire  64  is provided for deflection of the intermediate section  14 . The second puller wire  65  is provided for contracting the mapping assembly  17 . Each puller wire  64  and  65  extends from the control handle  16 , through the central lumen  18  of the catheter body  12  and into the first and second lumens  30  and  32  of the intermediate section  14 , respectively. The second puller wire  65  then extends into the second lumen  116  of the mapping assembly  17 . As described in more detail below, the proximal end of the first puller wire  64  is anchored within the control handle  16 , and the distal end of the first puller wire is anchored in the intermediate section  14 . Also as described further below, the proximal end of the second puller wire  65  is anchored within the control handle  16 , and the distal end of the second puller wire is anchored in the distal end of the mapping assembly  17 . 
   Each puller wire  64  and  65  is made of any suitable metal, such as stainless steel or Nitinol. Preferably each puller wire  64  and  65  has a coating (not shown), such as a coating of Teflon or the like. Each puller wire  64  and  65  has a diameter preferably ranging from about 0.006 inch to about 0.010 inch. 
   In the depicted embodiment, the first puller wire  64  is anchored at its distal end to the distal end of the intermediate section  14  using a T-shaped anchor, as shown in  FIG. 3 , which comprises a short piece of tubular stainless steel  80 , e.g., hypodermic stock, which is fitted over the distal end of the first puller wire  64  and crimped to fixedly secure it to the first puller wire. The distal end of the tubular stainless steel  80  is fixedly attached, e.g., by welding, to a cross-piece  82  formed of stainless steel ribbon or the like. The cross-piece  82  sits beyond the distal end of the first lumen  30 . The cross-piece  82  is larger than the lumen opening and, therefore, cannot be pulled through the opening. The distal end of the first lumen  30  is then filled with glue or the like, preferably a polyurethane glue. Within the first lumen  30  of the intermediate section  14 , the first puller wire  64  extends through a plastic, preferably Teflon® puller wire sheath (not shown), which prevents the first puller wire  64  from cutting into the wall of the intermediate section  14  when the intermediate section is deflected. Alternatively, the first puller wire  64  could be anchored to the side wall of the intermediate section  14  in a similar manner, where the T-shaped anchor extends into a notch in the side wall rather than beyond the distal end of the first lumen  30 . Such a design is disclosed in U.S. Pat. No. 6,064,908, the disclosure of which is incorporated herein by reference. 
   The second puller wire  65  is anchored in the distal end of the second lumen  116  of the mapping assembly in a manner similar to the first puller wire  64 . A T-shaped anchor is mounted on the distal end of the second puller wire  65 , extends into a notch in the side wall of the non-conductive covering  28 , and is held in place with polyurethane glue or the like. Any other suitable method for anchoring the puller wires  64  and  65  could also be used. 
   In the depicted embodiment, two compression coils  66  are situated within the catheter body  12 , each in surrounding relation to a corresponding puller wire  64  and  65 . Each compression coil  66  extends from the proximal end of the catheter body  12  to the proximal end of the intermediate section  14 . The compression coils  66  are made of any suitable metal, preferably stainless steel. Each compression coil  66  is tightly wound on itself to provide flexibility, i.e., bending, but to resist compression. The inner diameter of each compression coil  66  is preferably slightly larger than the diameter of the corresponding puller wire  64  and  65 . The Teflon® coatings on the puller wire  64  allow them to slide freely within the compression coils  66 . The outer surfaces of the compression coil  66  are covered by flexible, non-conductive sheathes  68 , e.g., made of polyimide tubing. 
   Each compression coil  66  is anchored at its proximal end to the outer wall  20  of the catheter body  12  by proximal glue joint  70  and at its distal end to the intermediate section  14  by distal glue joint  72 . Both glue joints  70  and  72  preferably comprise polyurethane glue or the like. The glue may be applied by means of a syringe or the like through a hole made between the outer surface of the catheter body  12  and the central lumen  18 . Such a hole may be formed, for example, by a needle or the like that punctures the outer wall  20  of the catheter body  12  which is heated sufficiently to form a permanent hole. The glue is then introduced through the hole to the outer surfaces of the compression coils  66  and wicks around the outer circumferences to form a glue joint about the entire circumferences of the compression coils. If desired, the compression coils  66  could be anchored at different longitudinal locations or eliminated altogether. 
   Longitudinal movement of each of the puller wires  64  and  65  relative to the catheter body  12  is accomplished by suitable manipulation of the control handle  16 . An embodiment of the control handle  16  according to the invention is shown in  FIGS. 9 to 11 . The control handle  16  comprises a generally tubular housing  86  having a longitudinal axis and proximal and distal ends and a generally tubular core  90  extending within the housing along its longitudinal axis. In the depicted embodiment, the core  90  is a separate piece that is fixedly attached to the handle housing  86  for ease in manufacturing, although the core could be formed integral with the housing if desired. The core  90  has proximal and distal ends that extend beyond and outside the proximal and distal ends, respectively, of the housing  86 . The catheter body  12  is fixedly attached to the distal end of the core  90  by means of a glue joint and shrink sleeve, as is generally known to those skilled in the art, or by any other suitable method. The puller wires  64  and  65 , lead wires  50  and any other wires, tubes or cables that extend through the catheter body  12  extend through a lumen or passage  88  in the core  90 , although the lead wires  50  are not shown in  FIGS. 9 to 11  for clarity. An elongated slot  102  extends through a portion of the length of the core  90 . 
   A piston  84  is mounted within the housing  86  in surrounding relation to the core  90 . The piston  84  has a tubular distal end  85  and a semicircular proximal end  87 . The semicircular proximal end  87  is shaped so that its inner surface fits generally against the tubular core  102 . The precise shape of the piston  84  is not critical to the invention. When the handle  16  is assembled, a portion of the distal end  85  of the piston  84  extends outside the distal end of the handle housing  86 . The distal end  85  of the piston  84  comprises threading  89  to provide a means for mounting a thumb control  92 , having corresponding internal threading (not shown), onto the piston. A preferred arrangement for mounting the thumb control  92  on the piston  84  is described in U.S. patent application Ser. No. 09/546,310 filed Apr. 10, 2000, entitled “Single Gear Drive Bi-Directional Control Handle for Steerable Catheter,” the disclosure of which is incorporated herein by reference. With this design, the user can cause longitudinal movement of the piston  84  relative to the handle housing  86  by pushing or pulling the piston  84  (directly or via the thumb control  92 ). 
   The proximal end of the first puller wire  64  is anchored to the piston  84  by any suitable method. In the depicted embodiment, as shown in  FIG. 12 , the proximal end of the piston  84  comprises a generally rectangular opening  118  having a slanted edge  119 . The opening  118  extends through a wall of the piston  84 . A channel  121 , which only extends a part of the way through the wall of the piston  84 , is provided proximal the opening  118 . A small groove  122  having a width less than that of the channel  121  connects the channel to the opening  118 . The first puller wire  64  extends through the lumen  88  in the core  90 , through the slot  102  in the core, through the opening  118  in the piston  84 , through the small groove  122 , and into the channel  121 . The first puller wire  64  is anchored in the channel  121  by means of a puller wire anchor  124 , which preferably comprises a short piece of hypodermic stock that is fixedly attached, e.g., by crimping, to the proximal end of the first puller wire  64  after it has passed through the small groove  122 . The puller wire anchor  124  has a diameter greater than the width of the small groove  122  and thus prevents the proximal end of the first puller wire  64  from being pulled through the small groove. The length of the opening  118  is limited such that, when the piston  84  is in its most distal position relative to the housing  86 , the opening does not extend outside the housing. However, the opening  118  is preferably long enough so that the first puller wire  64  extends through the opening at an angle rather than bending or kinking. 
   Because the catheter body  12  is attached to the core  90 , proximal movement of the piston  84  relative to handle housing  86  and core  90  causes proximal movement of the piston and first puller wire  64  relative to the catheter body  12 . Such movement results in deflection of the intermediate section  14  in the direction of the side of the first off-axis lumen  30  through which the first puller wire extends. 
   As shown in  FIG. 9 , the second puller wire  65  is anchored at its proximal end to a threaded slide  100 , which is disposed in the slot  102  of the core  90 , by any suitable method. In the depicted embodiment, the slide  100  comprises a generally solid, generally rectangular piece of plastic with threading  101  along one surface. The slide  100  has a generally rectangular hole  103  in which the distal end of the second puller anchor  65  in anchored with a puller wire anchor  125 , in a manner similar to the first puller wire  64 , discussed above. 
   The threaded slide  100  is mounted within the slot  102  in the core  90  such that the threaded slide is prevented from rotating, but is able to move longitudinally within the slot, thus producing a relative lateral motion between the threaded slide and the core. The handle housing  86  has a window  104 , through which the threaded surface  101  of the threaded slide  100  protrudes when the handle is assembled. The window has first and second window edges  118  and  120 , which limit the lateral movement of the threaded slide  100 . 
   A threaded sleeve  98  is mounted between first and second shoulders  106  and  108  on the handle housing  86 . The threaded sleeve  98  has internal threading that engages the threads  101  of the threaded slide  100 , such that rotation of the threaded sleeve causes the threaded slide to move longitudinally within the slot  102  in the core  90 . Other arrangements for slidably mounting the threaded slide  100  within the handle housing  86  could also be used in accordance with the invention. For example, the threaded slide  100  could be mounted over or around the core  90  instead of within a slot in the core. 
   Because the proximal end of the second puller wire  65  is attached to the threaded slide  100  and the core  90  is attached to the catheter body  12 , longitudinal movement of the threaded slide relative to the core results in corresponding movement of the second puller wire relative to the catheter body. Therefore, when the threaded sleeve  98  is rotated, the second puller wire  65  moves proximally relative to the catheter body  12 , thus causing the straight distal region  40  of the mapping assembly  17  to also move relative to the catheter body and arc proximally or deflect. The deflection of the straight distal region  40  of the mapping assembly  17 , in turn, causes the circular main region  39  of the mapping assembly to contract to thereby have a smaller diameter. 
   In one embodiment, the threaded sleeve  98  has a longitudinal slit and comprises a flexible material, such as delryn. To mount the threaded sleeve  98  over the handle housing  86 , the sleeve is separated along the slit and fit over the housing, such that the sleeve is disposed between the shoulders  106  and  108  of the handle housing. Alternatively, the threaded sleeve  98  may be formed from two halves that are fit over the housing  86  and then affixed together, such as by weld, adhesive, a screw, a rivet or the like. In the depicted embodiment, a gripping sleeve  112  is mounted over the threaded sleeve  98  to aid in rotating the sleeve and provide comfort to the user. The gripping sleeve  112  may comprise a high friction surface, such as rubber. The gripping sleeve  112  also aides in holding the threaded sleeve  98  together when the sleeve is assembled on the handle housing  86 . 
   In the depicted embodiment, the threaded sleeve  98  goes around the entire circumference of the handle housing  86 . If desired the threaded sleeve  98  could be replaced with another rotatable member that extends around only a part of the circumference of the handle housing  86 . 
   If desired, a fastener (not shown) can be provided to maintain the handle housing  86  in place over the core  90 . A description of such an arrangement is provided in U.S. patent application Ser. No. 09/546,310 filed Apr. 10, 2000, entitled “Single Gear Drive Bi-Directional Control Handle for Steerable Catheter,” the disclosure of which is incorporated herein by reference. 
   In use, a suitable guiding sheath is inserted into the patient with its distal end positioned at a desired mapping location. An example of a suitable guiding sheath for use in connection with the present invention is the Preface™ Braiding Guiding Sheath, commercially available from Cordis Webster (Diamond Bar, Calif.). The distal end of the sheath is guided into one of the atria. A catheter in accordance with the present invention is fed through the guiding sheath until its distal end extends out of the distal end of the guiding sheath. As the catheter is fed through the guiding sheath, the mapping assembly  17  is straightened to fit through the sheath. Once the distal end of the catheter is positioned at the desired mapping location, the guiding sheath is pulled proximally, allowing the deflectable intermediate section  14  and mapping assembly  17  to extend outside the sheath, and the mapping assembly  17  returns to its original shape due to the shape-memory of the support member  24 . The mapping assembly  17  is then inserted into a pulmonary vein or other tubular region (such as the coronary sinus, superior vena cava, or inferior vena cava) so that the outer circumference of the generally circular main region  39  of the assembly is in contact with a circumference inside the tubular region. Preferably at least about 50%, more preferably at least about 70%, and still more preferably at least about 80% of the circumference of the generally circular main region is in contact with a circumference inside the tubular region. 
   The circular arrangement of the electrodes  36  permits measurement of the electrical activity at that circumference of the tubular structure so that ectopic beats between the electrodes can be identified. The size of the generally circular main region  39  permits measurement of electrical activity along a diameter of a pulmonary vein or other tubular structure of or near the heart because the circular main region has a diameter generally corresponding to that of a pulmonary vein or the coronary sinus. Additionally, because the main region  39  preferably does not form a flat circle, but instead is somewhat helical, as shown in  FIG. 4 , it is easier for the user to guide the mapping assembly  17  into a tubular region. If the circumference of the main region  39  of the mapping assembly  17  is larger than the circumference of the structure to be mapped, the mapping assembly can be contracted by longitudinal movement of the second puller wire  65  using the control handle  16 , as described above. 
   The inventive handle is not limited to the above-described catheter design. The handle is also particularly useful for bi-directional catheters and other catheters having two puller wires for deflection of the distal end of the catheter body, i.e., the intermediate section. Such catheters are described in U.S. Pat. Nos. 6,171,277, 6,183,463, 6,198,974, 6,210,407, and 6,267,746, U.S. patent application Ser. No. 09/822,087, filed Mar. 30, 2001, “Steerable Catheter with a Control Handle Having a Pulley Mechanism,” and U.S. patent application Ser. No. 09/846,732, filed Apr. 30, 2001, entitled “Asymmetrical Bidirectional Steerable Catheter,” the disclosures of which are incorporated herein by reference. Other uses for the handle of the invention would be recognized by one skilled in the art. 
   The preceding description has been presented with reference to presently preferred embodiments of the invention. Workers skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structure may be practiced without meaningfully departing from the principal, spirit and scope of this invention. 
   Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and illustrated in the accompanying drawings, but rather should be read consistent with and as support to the following claims which are to have their fullest and fair scope.