Patent Publication Number: US-2021187247-A1

Title: Catheter with multi-functional control handle having linear mechanism

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of and claims priority to and the benefit of U.S. application Ser. No. 16/030,601 filed Jul. 9, 2018, now U.S. Pat. No. 10,940,291, which is a continuation of and claims priority to and the benefit of U.S. patent application Ser. No. 15/431,648 filed Feb. 13, 2017, now U.S. Pat. No. 10,016,576, which is a continuation of and claims priority to and the benefit of U.S. application Ser. No. 14/300,063, filed Jun. 9, 2014, now U.S. Pat. No. 9,566,416, which is a continuation of and claims priority to and the benefit of U.S. application Ser. No. 12/550,204 filed Aug. 28, 2009, now U.S. Pat. No. 8,747,351, the entire contents of all of which are incorporated herein by reference. 
    
    
     FIELD OF INVENTION 
     This invention relates to a catheter, in particular, a catheter with a control handle having multiple control mechanisms for deflecting and contracting portions of the catheter. 
     BACKGROUND 
     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. Atrial fibrillation is a common sustained cardiac arrhythmia and a major cause of stroke. This condition is perpetuated by reentrant wavelets propagating in an abnormal atrial-tissue substrate. Various approaches have been developed to interrupt wavelets, including surgical or catheter-mediated atriotomy. Prior to treating the condition, one has to first determine the location of the wavelets. Various techniques have been proposed for making such a determination, including the use of catheters with a mapping assembly that is adapted to measure activity within a pulmonary vein, coronary sinus or other tubular structure about the inner circumference of the structure. One such mapping assembly has a tubular structure comprising a generally circular main region generally transverse and distal to the catheter body and having an outer circumference and a generally straight distal region distal to the main region. The tubular structure comprises a non-conductive cover over at least the main region of the mapping assembly. A support member having shape-memory is disposed within at least the main region of the mapping assembly. A plurality of electrode pairs, each comprising two ring electrodes, are carried by the generally circular main region of the mapping assembly. 
     In use, the electrode catheter is inserted into a guiding sheath which has been positioned a major vein or artery, e.g., femoral artery, and guided into a chamber of the heart. Within the chamber, the catheter is extended past a distal end of the guiding sheath to expose the mapping assembly. The catheter is maneuvered through movements that include deflection of a distal portion of the catheter so that the mapping assembly is positioned at the tubular region in the heart chamber. The ability to control the exact position and orientation of the catheter and also the configuration of the mapping assembly is critical and largely determines how useful the catheter is. 
     Steerable catheters are generally well-known. For example, U.S. Pat. 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 elongated catheter body is attached to the piston. A puller wire is attached to the housing and extends through the piston, through the catheter body, and into a tip section at the distal end of 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 catheter tip section. 
     The design described in U.S. Pat. No. RE 34,502 is generally limited to a catheter having a single puller wire. If bi-directional deflection is desire, more than one puller wire becomes necessary. Moreover, if more control is desired, such as contraction of the mapping assembly, an additional puller wire is needed. Space is limited within a control handle and operation of puller wire control mechanisms must not interfere with components that extend through the control handle, such as lead wires, cables, and irrigation tubing. Moreover, it is desirable that the control mechanisms be arranged such that the catheter can be operated single-handedly by the user. Accordingly, a need exists for a control handle capable of moving three puller wires for at least two independent movements, such as bi-directional deflection of the catheter shaft and contraction of the mapping assembly, preferably through a single-handed manipulation of the user. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a catheter for use in a patient&#39;s heart, especially for mapping a tubular region of the heart. In one embodiment, the catheter has a catheter body and a deflectable intermediate section distal the catheter body. Distal the intermediate section is a mapping assembly that has a generally circular portion adapted to sit on or in a tubular region of the heart. A control handle of the catheter allows for single-handed manipulation of various control mechanisms that can deflect the intermediate section and contract the mapping assembly by means of a deflection control assembly and a linear control assembly. The deflection control assembly has a deflection arm and a rocker member. The linear control assembly has a linear control member, an inner rotational member and a cam. A pair of puller members are responsive to the deflection control assembly to bi-directionally deflect the intermediate section. A third puller member is responsive to the linear control assembly to contract the generally circular portion of the mapping assembly. 
     In a more detailed embodiment, a proximal end of the third puller member is anchored in the linear control assembly, such that actuation of the linear control member by a user moves the third puller member longitudinally relative to the catheter body. The linear control member has a portion that slidably engages housing of the control handle, and a projection that is received in a track formed on the inner rotational member such that distal and proximal movement of the control member along the longitudinal axis of the control handle rotates the inner rotational member to expand or retract the mapping assembly. Situated between the inner rotational member and the cam, a follower to which a proximal end of the third puller member is anchored is guided by a slot formed in the inner rotational member so as to slide in a cam track formed on the cam. Both the cam track and the track formed on the inner rotational member are helical to maximize efficiency of the linear control assembly in occupying a relatively small space in the control handle to achieve the linear motion desirable for expanding and contracting mapping assembly. 
    
    
     
       BRIEF 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. It is understood that selected structures and features have not been shown in certain drawings so as to provide better viewing of the remaining structures and features. 
         FIG. 1  is a top plan view of one embodiment of the catheter of the present invention. 
         FIG. 2 a    is a side cross-sectional view of an embodiment of a junction of a catheter body and an intermediate section, taken along a first diameter. 
         FIG. 2 b    is a side cross-sectional view of the embodiment of the junction of  FIG. 2 a   , taken along a second diameter generally perpendicular to the first diameter. 
         FIG. 3  is a side view of a distal portion of the catheter of  FIG. 1 , including an intermediate section and a mapping assembly. 
         FIG. 4  is a longitudinal cross-sectional view of the intermediate section of  FIG. 3 , taken along line  4 - 4 . 
         FIG. 5  is a schematic view of the mapping assembly showing one arrangement of the ring electrodes. 
         FIG. 6  is a longitudinal cross-sectional view of the mapping assembly of  FIG. 3  along line  6 - 6 . 
         FIG. 7  is a side cross-sectional view of an embodiment of a distal end of the mapping assembly of  FIG. 3 . 
         FIG. 8 a    is a side cross-sectional view of an embodiment of a junction between the intermediate section and the mapping assembly, taken along a first diameter. 
         FIG. 8 b    is a side cross-sectional view of an embodiment of a junction between the intermediate section and the mapping assembly, taken along a second diameter generally perpendicular to the first diameter. 
         FIG. 9  is a top plan view of an embodiment of a control handle housing half including an embodiment of a deflection control assembly. 
         FIG. 10  is a top perspective view of an embodiment of a rocker member of a deflection control assembly. 
         FIG. 11  is a bottom perspective view of an embodiment of a rocker member. 
         FIG. 12  is a side view of an embodiment of a pulley of a deflection control assembly. 
         FIGS. 13 a -13 c    are schematics of an embodiment of the deflection control assembly in neutral and rotated configurations. 
         FIG. 14  is a longitudinal cross section of an embodiment of the deflection control assembly and tension control assembly mounted on a control handle. 
         FIG. 14 a    is a detailed view of a portion of  FIG. 14 , including an embodiment of a retaining nut and a tension screw. 
         FIG. 15  is a partial perspective view of an embodiment of a first control handle housing half. 
         FIG. 16  is a perspective view of an embodiment of a deflection arm. 
         FIG. 17  is a perspective view of an embodiment of a tension control dial. 
         FIG. 18  is a perspective view of an embodiment of a locking plate. 
         FIG. 19  is a partial perspective view of a portion of an embodiment of a control handle. 
         FIG. 20  is a partial perspective view of a portion of an embodiment of a deflection arm and a tension control member mounted on a control handle. 
         FIG. 21  is a partial perspective view of a portion of an embodiment of a second control handle housing half and a retaining nut, the second control housing half adapted to oppose the first control handle housing half. 
         FIG. 22  is a perspective view of the tension control dial of  FIG. 17  and locking plate of  FIG. 18  as assembled. 
         FIG. 23  is an exploded perspective view of an embodiment of a linear control assembly. 
         FIG. 24  is a side cross-sectional view of the linear control assembly of  FIG. 23 , as assembled on a control handle. 
         FIG. 25  is a longitudinal cross-sectional view of the linear control assembly of  FIG. 24 , taken along line a-a. 
         FIG. 26  is a longitudinal cross-sectional view of the linear control assembly of  FIG. 24 , taken along line b-b. 
         FIG. 27  is a longitudinal cross-sectional view of the linear control assembly of  FIG. 24 , taken along line c-c. 
         FIG. 28  is a side cross-sectional view of an alternate embodiment of the linear control assembly, as assembled on a control handle. 
         FIG. 29  is a longitudinal cross-sectional view of the linear control assembly of  FIG. 28 , taken along line a-a. 
         FIG. 30  is a longitudinal cross-sectional view of the linear control assembly of  FIG. 28  taken along line b-b. 
         FIG. 31  is a longitudinal cross-sectional view of the linear control assembly of  FIG. 28 , taken along line c-c. 
         FIG. 32  is a partial perspective view of an alternate embodiment of a control handle housing half. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , the present invention is directed to a catheter  10  with multiple control capabilities for mapping and/or ablation of the heart. In the illustrated embodiment of  FIG. 1 , a catheter  10  comprises an elongated catheter body  12 , a deflectable intermediate section  14  at a distal end of the catheter body  12 , a tip section  15  including a mapping assembly  17  at a distal end of the intermediate section  14 , and a multi-functional control handle  16  at a proximal end of the catheter body  12  for controlling portions of the catheter, for example, deflecting the intermediate section  14  and contracting the mapping assembly  17 . 
     With reference to  FIGS. 2 a  and 2 b   , the catheter body  12  comprises a single, central or axial lumen  18 . The catheter body  12  is flexible, i.e., bendable, but substantially non-compressible along its length. The catheter body  12  may be of any suitable construction and made of any suitable material. In one embodiment, the catheter body  12  comprises an outer wall  22  made of a polyurethane or nylon. The outer wall  22  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 tip section 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. Likewise the thickness of the outer wall  22  is not critical. The inner surface of the outer wall  22  is lined with a stiffening tube  20 , which can be made of any suitable material, preferably polyimide. The stiffening tube  20  is held in place relative to the outer wall  22  at the proximal end of the catheter body  12 . A first glue joint  23  is made between the distal ends of the stiffening tube  20  and the outer wall  22  by a fast drying glue, e.g. Super Glue® Thereafter a second glue joint  25  is formed between the proximal ends of the stiffening tube  20  and outer wall  22  using a slower drying but stronger glue, e.g., polyurethane. 
     The stiffening tube, along with the braided outer wall  22 , provides improved torsional stability while at the same time minimizing the wall thickness of the catheter, thus maximizing the diameter of the single lumen. The outer diameter of the stiffening tube  20  is about the same as or slightly smaller than the inner diameter of the outer wall  22 . Polyimide tubing is suitable because it may be very thin walled while still providing very good stiffness. This maximizes the diameter of the central lumen  18  without sacrificing strength and stiffness. Polyimide material is typically not used for stiffening tubes because of its tendency to kink when bent. However, it has been found that, in combination with an outer wall  22  of polyurethane, nylon or other similar material, particularly having a stainless steel braided mesh, the tendency for the polyimide stiffening tube  20  to kink when bent is essentially eliminated with respect to the applications for which the catheter is used. 
     In one embodiment, the outer wall  22  has an outer diameter of about 0.092 inch and an inner diameter of about 0.063 inch and the polyimide stiffening tube  20  has an outer diameter of about 0.0615 inch and an inner diameter of about 0.052 inch. 
     As shown in  FIGS. 2 a , 2 b    and  4 , the intermediate section  14  comprises a shorter section of tubing  19  with multiple off-axis lumens, for example, first, second, third and fourth lumens  30 ,  31 ,  32  and  33 . The tubing  19  is made of a suitable non-toxic material which is preferably more flexible than the catheter body  12 . A suitable material for the tubing  19  is braided polyurethane, i.e., polyurethane with an embedded mesh of braided stainless steel or the like. The outer diameter of the intermediate section  14 , like that of the catheter body  12 , is preferably no greater than about 8 French. The size of the lumens is not critical. In one embodiment, the intermediate section has an outer diameter of about 7 French (0.092 inch) and the lumens are generally about the same size, having a diameter of about 0.022 inch, or selected lumens can have a slightly larger diameter of about 0.036 inch. 
     A means for attaching the catheter body  12  to the intermediate section  14  is illustrated in  FIGS. 2 a  and 2 b   . The proximal end of the intermediate section  14  comprises an inner counter bore  24  that receives the outer surface of the polyimide stiffener  20 . The intermediate section  14  and catheter body  12  are attached by glue  29  or the like. 
     As shown in  FIGS. 2 a  and 2 b   , extending through the single lumen  18  of the catheter body  12  are various components, for example, lead wires and multiple puller members, and any other wires or cables. Longitudinal movement of the puller members relative to the catheter body  12  enable user control of various parts of the catheter via the control handle. In one embodiment, the puller members include a pair of deflection puller members  42  for deflecting the intermediate section  14  and a contraction puller member  35  for adjusting the mapping assembly  17  of the tip section  15 . 
     A single lumen catheter body  12  may be preferred over a multi-lumen body because the single lumen  18  body can permit better tip control when rotating the catheter  10 . The single lumen  18  permits the components passing therethrough to float freely within the catheter body. If such components were restricted within multiple lumens, they can build up energy when the handle  16  is rotated, resulting in the catheter body  12  having a tendency to rotate back if, for example, the handle is released, or if bent around a curve, to flip over, either for which are undesirable performance characteristics. 
     A deflection puller member  42  extends through the central lumen  18  of the catheter body  12  and into the second lumen  31  of the intermediate section  14 . Another deflection puller member  42  extends through the central lumen  18  and into the fourth lumen  33  of the intermediate section  14 . The distal ends of the deflection puller members  42  are anchored to the wall of the tubing  19  near the distal end of the intermediate section  14  by means of T-anchors  83  ( FIG. 8B ). In the intermediate section  14 , each deflection puller members  42  extends through a plastic, e.g. Teflon®, sheath  81 , which prevents the deflection puller members  42  from cutting into the wall of the tubing  19  of the intermediate section  14  when the intermediate section  14  is deflected. 
     As shown in  FIG. 2 b   , compression coils  44  in surrounding relation to the deflection puller members  42  extend from the proximal end of the catheter body  12  to the proximal end of the intermediate section  14 . The compression coils  44  are made of any suitable metal, e.g., stainless steel. The compression coils  44  are tightly wound on itself to provide flexibility, i.e., bending, but to resist compression. The inner diameter of the compression coils  44  is preferably slightly larger than the diameter of the puller wires  42 . For example, when a puller member  42  has a diameter of about 0.007 inches, the compression coil  44  preferably has an inner diameter of about 0.008 inches. The Teflon® coating on the puller member  42  allows them to slide freely within the compression coils  44 . The outer surface of the compression coils  44  is covered by a flexible, non-conductive sheath  27  to prevent contact between the compression coils  44  and other components, such as lead wires and cables, etc. In one embodiment, a non-conductive sheath is made of polyimide tubing. 
     The compression coils  44  are anchored at their proximal ends to the proximal end of the stiffening tube  20  in the catheter body  12  by glue joint  50  ( FIG. 2 b   ) and at its distal end near the proximal end of the intermediate section  14  in the second lumen  31  and fourth lumen  33  by glue joints  49  ( FIG. 2 b   ). 
     With reference to  FIG. 3 , at the distal end of the intermediate section  14  is the mapping assembly  17 . The mapping assembly  17  comprises a generally straight proximal region  38  and a generally circular main region  39 . The proximal region  38  is mounted on the intermediate section  14 , as described in more detail below, so that its axis can be a linear axial extension of the intermediate section  14 . The proximal region  38  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, but can vary as desired. 
     The generally circular main region  39  is generally traverse, if not also perpendicular, to the catheter body  12  and the intermediate section  14 . The generally circular main region  39  can form a flat circle or can be very slightly helical. The main region  39  has an outer diameter preferably ranging from about 10 mm to about 25 mm, more preferably about 12 mm to about 20 mm. The generally circular main region  39  can curve in a clockwise direction or a counterclockwise direction. As shown in  FIGS. 5, 6 and 7 , the mapping assembly  17  is formed of a non-conductive cover or tubing  52  which can have any cross-sectional shape as desired. The non-conductive cover  52  can be made of any suitable material, and is preferably made of a biocompatible plastic such as polyurethane or PEBAX. The non-conductive cover  52  can be pre-formed into the desired generally circular shape of the generally circular main region  39 . Alternatively, the shape of the generally circular main region  39  can be defined by a wire or other component extending through the non-conductive cover  52 . 
     In the depicted embodiment, a pre-formed support member  54  extends through the non-conductive cover  52  to define the shape of the generally circular main region  39 . The support member  54  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 suitable material for the support member  54  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 suitable nickel/titanium alloy is Nitinol, which has excellent shape memory, together with ductility, strength, corrosion resistance, electrical resistivity and temperature stability. 
     A series of ring electrodes  26  are mounted on the non-conductive cover  52  of the generally circular main region  39  of the mapping assembly  17 , as shown in  FIG. 5 . The ring electrodes  26  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 cover  52  with glue or the like. Alternatively, the ring electrodes  26  can be formed by coating the non-conductive cover  52  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. A suitable mapping assembly is described in U.S. Pat. No. 7,274,957, the entire disclosure of which is hereby incorporated by reference. If desired, additional electrodes (not shown) could be mounted along the intermediate section  14  and/or the generally straight proximal section  38 . 
     The contraction puller member  35 , for example, a contraction puller wire, is provided to contract the generally circular main region  39  to thereby change or reduce its diameter, for example, when mapping or ablating circular or tubular regions of the heart. The contraction wire  35  has a proximal end anchored in the control handle  16 , which is used to manipulate the contraction wire as described further below. The contraction wire  35  extends through the central lumen  18  of the catheter body  12 , through the third lumen  32  of the intermediate section  14  and into the non-conductive cover  52  of the mapping assembly  17 . The portion of the contraction wire  35  extending through the non-conductive cover  52  is positioned on the side of the generally circular main region  39  closer to the center of the generally circular main region, as best shown in  FIG. 6 . The center of the generally circular main region refers to the center of the circle formed by the generally circular main region. With this arrangement, contraction of the generally circular main region  39  is dramatically improved over arrangements where the position of the contraction wire  35  is not so controlled. 
     As shown in  FIGS. 5 and 6 , within the mapping assembly  17 , the contraction wire  35  extends through a plastic tube  55 . In one embodiment, the plastic tube  55  comprise three layers, including an inner layer of polyimide over which a braided layer is formed, the braided layer comprising a braided stainless steel mesh or the like, as is generally known in the art. The braided layer enhances the strength of the plastic tube  55 , reducing the tendency for contraction wire  35  to straighten the preformed curve of the mapping assembly  17 . A thin plastic layer of polytetrafluoroethylene is provided over the braided layer to protect the braided layer from getting tangled with the lead wires  40  within the non-conductive cover  52 . The plastic tube  55  has a proximal end anchored to the distal end of the intermediate section  14  in the third lumen  32  by glue or the like ( FIG. 8 a   ). The support member  54  extends through the plastic tube  55  with the contraction wire  35  ( FIG. 8 a   ). The distal ends of the support member  54  and the contraction wire  35  are soldered or otherwise attached to a small stainless steel tube  53  ( FIG. 7 ). With this arrangement, the relative positions of the contraction wire  35  and the support member  54  can be controlled so that the contraction wire can be positioned on the side of the generally circular region  39  closer to the center of the generally circular region  39 , as described above. The contraction wire  35  on the inside of the curve pulls the support member  54  to the inside of the curve, enhancing contraction of the generally circular region  39 . Further, when the plastic tube  55  includes a braided layer, it keeps the contraction wire  35  from tearing through the non-conductive cover  52 . 
     A third compression coil  46  is situated within the catheter body  12  and intermediate section shaft  14  in surrounding relation to the contraction wire  35  ( FIG. 2 a   ). The third compression coil  46  extends from the proximal end of the catheter body  12  and to near the distal end of the third lumen  32  of the intermediate section  14 . The third compression coil  46  is made of any suitable metal, such as stainless steel, and is tightly wound on itself to provide flexibility, i.e., bending, but to resist compression. The inner diameter of the third compression coil  46  is preferably slightly larger than the diameter of the contraction wire  35 . The outer surface of the compression coil  46  is covered by a flexible, non-conductive sheath  68 , e.g., made of polyimide tubing. The third compression coil  46  preferably is formed of a wire having a square or rectangular cross-sectional area, which makes it less compressible than a compression coil formed from a wire having a circular cross-sectional area. As a result, the third compression coil  46  keeps the catheter body  12 , and particularly the intermediate section  14 , from deflecting when the contraction wire  35  is manipulated to contract the mapping assembly  17  as it absorbs more of the compression. 
     The third compression coil  46  is anchored at its proximal end to the outer wall  20  of the catheter body  12  by the proximal glue joint  50  and to the intermediate section  14  by distal glue joint  72 . 
     It is understood that glue joints throughout the catheter  10  may comprise polyurethane glue or the like. The glue may be applied by means of a syringe or the like through a hole made in the tubing walls. Such a hole may be formed, for example, by a needle or the like that punctures the tubing walls where the needle is heated sufficiently to form a permanent hole. The glue is then introduced through the hole to wick around the component(s) within the tubing to form a glue joint about the entire circumference of the component(s). 
     In the depicted embodiment of  FIG. 7 , the distal end of the mapping assembly  17  is sealed closed with a dome  51  of polyurethane glue or the like. A short ring  56 , made of metal or plastic, and preferably polyamide, is mounted within the distal end of the non-conductive cover  52 . The short ring  56  prevents the distal end of the non-conductive cover  52  from collapsing, there by maintaining the diameter of the non-conductive cover at its distal end. 
     At the junction of the intermediate section  14  and the mapping assembly  17  as shown in  FIGS. 8 a  and 8 b   , the non-conductive cover  52  is attached to the intermediate section  14  by glue or the like. The plastic tube  55  has its proximal end inserted and glued in the distal end of the intermediate section  14 . The glue (not shown) from the plastic tube  55  can further serve to anchor the distal end of the third compression coil  46  in place within the third lumen  32 . The support member  54  extends from the third lumen  32  into the plastic tube  55  within the non-conductive cover  52 . The proximal end of the support member  54  terminates a short distance proximally from the distal end of the third lumen  32 , approximately about 5 mm, so as not to adversely affect the ability of the intermediate section  14  to deflect. However, if desired, the proximal end of the support member  54  can extend proximally further into the intermediate section  14  and/or the catheter body  12 . 
     The lead wires  40  attached to the ring electrodes  26  extend through the first lumen  30  of the intermediate section  14  ( FIG. 2 a   ), through the central lumen  18  of the catheter body  12 , through the control handle  16 , and terminate at their proximal end in a connector (not shown) which is connected to an appropriate monitor or other device for receiving and displaying the information received from the ring electrodes  26 . The portion of the lead wires  40  extending through the central lumen  18  of the catheter body  12 , control handle  16  and proximal end of the intermediate section  14  is 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 lead wire lumen  30  with polyurethane glue or the like to form glue joint  73 . 
     The lead wires  40  are attached to the ring electrode  26  by any conventional technique. In one embodiment, each ring electrode  26  is mounted by first forming a hole in the non-conductive cover  52 . An electrode lead wire  40  is fed through the hole, and the ring electrode  26  is welded in place over the lead wire and non-conductive cover  52 . 
     With reference to  FIG. 1 , the control handle  16  comprises a generally elongated handle housing, which can be made of any suitable rigid material, such as plastic configured through a suitable molding process. In the illustrated embodiment, the housing includes two opposing halves  16   a  and  16   b  that generally mirror each other and are joined by glue, sonic welding or other suitable means along a longitudinal peripheral seam  28  around the housing. In the illustrated embodiment, the cross section of the handle  16  formed by the opposing halves changes along the length of the handle. A more distal portion  112  has a smaller, generally rectangular cross section. A mid-portion  114  has a larger, generally rectangular cross section. A more proximal portion  116  has a generally circular cross section. 
     In the illustrated embodiment of  FIGS. 1 and 9 , the control handle  16  houses components of a deflection control assembly  74  in the mid-portion  114 . The deflection control assembly includes a deflection member or arm  75  that can be directly manipulated by an operator to control deflection of the intermediate section  14 . The deflection arm  75  is rotatable about an axis  76  that is generally transverse or perpendicular to the longitudinal axis of the control handle. The deflection control assembly  74  has a rotatable rocker member  78  that acts on the deflection puller members  42  to deflect the intermediate section  14 . The rocker member  78  has a length L dimension, a width W dimension and a thickness T dimension ( FIGS. 10 and 11 ). 
     Along its thickness dimension T, the rocker member  78  is configured with two opposing annular formations  140   a  and  140   b  that define a central hole or passage  143  that extends through its entire thickness. The central hole  143  is aligned with the rotational axis  76  of the deflection arm  75 . Along its length dimension L, the rocker member  78  also has two smaller holes  146  that oppose each other across the central hole  143 . In each hole sits a pulley  147 , for example, a snap bearing ( FIG. 12 ), that has a rotational axis parallel to the axis  76 . Each deflection puller member  42  enters the rocker member through slots  148  and a portion is wound around a respective pulley  147 . 
     As understood by one of ordinary skill in the art, the rocker member  78  and the pulleys  147  are arranged such that rotation of the rocker member in one direction about the axis  76  draws back one puller member  42  to deflect the intermediate section  14  in that direction. With reference to  FIGS. 13 a -13 c   , as the rocker member  78  is rotated by means of the deflection arm (as represented by line  75 ), the pulleys  147  are displaced from a neutral position ( FIG. 13 a   ) with one pulley  147  drawing a puller member  42  on one side of the catheter body  12  against its anchored proximal end for deflecting the intermediate section  14  toward that side ( FIGS. 13 b  and 13 c   ). 
     Each deflection puller member  42  may comprise multiple segments. As illustrated in  FIG. 9 , each deflection puller member has a distal puller wire  42   a  and a proximal fiber  42   b  that are joined or connected at a location within the control handle  16  distal the rocker member  78 . The puller wire  42   a  and the tensile fiber  42   b  of each deflection puller member are connected or secured to each other by a connector  154 , e.g., a crimped brass ferrule covered by shrink tubing. Each puller wire  42   a  extends through the catheter body  12  and the intermediate section  14 . Each tensile fiber  42   b  extends inside the control handle  16 . In this manner, it is the more flexible tensile fibers  42   b  that interact with the pulleys  147  and undergo repeated bending and straightening during deflection operations, as they are less prone to bending stress and fatigue failure. 
     Each puller wire  42   a  is made of any suitable metal, such as stainless steel or Nitinol. Preferably each puller wire has a low friction coating, such as a coating of Teflon® or the like. Each puller wire has a diameter preferably ranging from about 0.006 inch to about 0.012 inch. Preferably both of the puller wires have the same diameter. Flat puller wires may be used in place of round puller wires. Their cross sectional dimensions should be such that they provide comparable tensile strengths as round puller wires. 
     Each tensile fiber  42   b  may be of a high modulus fiber material, preferably having an ultimate tensile strength substantially in the range of 412-463 ksi (2480-3200 Mpa) such as High Molecular Density Polyethylene (e.g., Spectra™ or Dyneema™), a spun para-aramid fiber polymer (e.g., Kevlar™) or a melt spun liquid crystal polymer fiber rope (e.g., Vectran™), or a high strength ceramic fiber (e.g., Nextel™). The term fiber is used herein interchangeably with the term fibers in that the tensile fiber may be of a woven or braided construction. In any case, these materials tend to be flexible, providing suitable durability when used in wrapped engagement with the pulleys and the like for greater throw in deflecting the catheter tip. Further, they are substantially non-stretching, which increases the responsiveness to the manipulation of the control handle, and nonmagnetic so that they generally appear transparent to an MRI. The low density of the material causes it to be generally transparent to an x-ray machine. The materials can also be nonconductive to avoid shorting. Vectran™ for example, has high strength, high abrasion resistance, is an electrical insulator, nonmagnetic, is polymeric, and has low elongation under sustained loading conditions. 
     In the illustrated embodiment of  FIG. 9 , each tensile fiber  42   b  extends proximally from the connector  154  toward the rocker member  78  where each is wound around a respective pulley  147  and turns about 180 degrees to double back toward the distal end of the control handle. Each proximal end of the tensile fiber  42   b  is anchored by an anchor assembly  90  that includes a pair or racks  92 , a slug  94  and a stop  96 . The proximal end of each tensile fiber  22   b  extends between a channel  91  defined by the pair of racks  92 , and the proximal end of each tensile fiber is encased within a molded member or slug  94  sized to fit in and translate in the channel  91 . Proximal the slug are the stops  96  that are adjustably positioned in a selected location along the racks  92 , for example, by means of interlocking teeth  98  formed in the racks and the stops to releasably lock in the selected position against movement. The stops  96  are formed so that each respective tensile fiber  42   b  can slide through or below them while blocking the slugs  94  from moving proximally past them. Accordingly, the stops  96  limit the proximal movement of the slugs  94  and anchor the proximal ends of the tensile fibers  42   b  to effectuate deflection when each is drawn proximally by the deflection control assembly  74 . During assembly of the control handle  16 , before the two housing halves  16   a ,  16   b  are joined, the stops  96  are selectively positioned between the racks  92  to achieve a desirable tension in each tensile member. The interlocking teeth  98  of the racks  92  and stops  96  allow for fine adjustments in setting the tension. 
     The construction and assembly of the deflection control assembly  74  including the deflection arm  75  and a tension adjustment member  101  on the control handle  16  are described as follows. With reference to  FIGS. 14 and 14   a , the rocker member  78  of the assembly  74  is situated between the two halves  16   a  and  16   b  of the control handle  16 , with each of its annular formations  140   a  and  140   b  extending respectively through an opening  120   a ,  120   b  formed in the distal portion  114  of each housing half  16   a  and  16   b.    
     The annular formation  140   a  has recesses  160  ( FIG. 10 ) exposed through the opening  120   a  ( FIG. 15 ) that receive protrusions  152  projecting from a facing surface  154  of the deflection arm  75  ( FIG. 16 ) to rotationally couple the deflection arm  75  and the rocker member  78 . The protrusions  152  can snap fit into the recesses  160  and/or be secured by adhesives, glue, sonic welding and the like. A central circular protrusion  156  from the deflection arm  75  fits into the hole  143  circumscribed by the annular formation  140   a  of the rocker member  78 . A suitable deflection assembly and control handle are described in co-pending U.S. application Ser. No. 12/346,834, filed Dec. 30, 2008, entitled DEFLECTABLE SHEATH INTRODUCER, the entire disclosure of which is hereby incorporated by reference. Another suitable deflection assembly with deflection sensitivity is described in co-pending U.S. application Ser. No. 12/211,728, filed Sep. 16, 2008, entitled CATHETER WITH ADJUSTABLE DEFLECTION SENSITIVITY, the entire disclosure of which is hereby incorporated by reference. Therein, a cam that is responsive to a deflection sensitivity knob can vary the separation distance between the two pulleys  147 , thereby changing the deflection sensitivity of the deflection arm. 
     Opposing the deflection arm  75  is the deflection tension adjustment member or dial  101  ( FIGS. 17 and 20 ) which is coupled to and indirectly engaged with the rocker member  78  by various mechanisms and parts and allows an operator to adjust the ease with which the deflection arm  75  can be rotated. Mounted primarily on the housing half  16   b , the illustrated embodiment of a tension adjustment assembly  100  includes the adjustment dial  101  ( FIG. 17 ), a locking plate  102  ( FIG. 18 ), a tension cap screw  103 , a retaining nut  136  and a washer  119  (see  FIGS. 14 and 14   a ). A user rotates the dial  101  to adjust the tightness or tension of the rotational movement of deflection arm  75  by effectively compressing or releasing the rocker member  78  against the washer  119  (e.g., a Belleville type) and the control handle housing half  16   b.    
     The dial  101  has a generally circular cross section with a circumferential edge  115  having a friction-inducing surface ( FIG. 17 ). A central circular protrusion  105  and a plurality of prongs  106  ( FIG. 17 ) situated along a diameter of the dial project from a surface  104  of the dial  101 . 
     The locking plate  102  is sandwiched between the dial  101  and the handle housing  16   b  ( FIG. 20 ). The locking plate  102  ( FIG. 18 ) has a central larger hole  107  and two smaller holes  108 , all three of which extend through the entire thickness of the locking plate. The two prongs  106  of the dial  101  are adapted to be inserted through the smaller holes  108  in the plate  102  ( FIG. 21 ) and received in semi-circular grooves  109  ( FIG. 19 ) formed in an outer surface of the housing half  16   b . The grooves  109  limit the degree of rotation of the dial  101  in clockwise and counterclockwise directions. The central hole  107  of the plate  102  ( FIG. 18 ) has different cross-sections that include a larger circular cross-section  107   a  and a smaller circular cross-section  107   b . The larger circular cross-section  107   a  receives a head  112  of a cap screw  103 , and the smaller circular cross-section  107   b  receives a threaded body  115  of the cap screw  103  ( FIG. 14 a   ). 
     The threaded body  115  of the cap screw  103  extending through the central hole  107  of the locking plate  102  engages the retaining nut  136  situated in the opening  143  of the rocker member  78 . A head  115  of the nut abuts and is anchored against a neck  132  formed in the inner surface of the opening  143  of the rocker member  78 . The opening  120   b  in the housing half  16   b  ( FIG. 21 ) has a larger cross section  122  and a smaller cross section  124 . The smaller cross section  124  has a polygonal shape which matches a polygonal (e.g., hexagonal) end  126  of the nut  136  so that the nut  136  is effectively locked against rotation relative to the housing handle  16   b.    
     The central protrusion  105  of the dial  101  ( FIG. 17 ) forms a press or interference fit with the head  112  of the cap screw  103  to create rotational alignment between these two components. The prongs  106  of the dial  101  lock and rotationally couple the dial  101  and the lock plate  102 , and the cap screw  103  is rotationally coupled to the locking plate  102 . Coupling of the dial  101  and the locking plate  102  may also be achieved by means of welding the two components together. In that case, the prongs  106  need not protrude from the dial  101  but can instead extend from the locking plate  102 . 
     Between the polygonal end  126  of the nut  136  and the housing handle  16   b  is the washer  119  whose compression against the nut  136  and the housing handle  16   b  is adjustable by the user&#39;s rotation of the dial  101  which tightens or releases the engagement between cap screw  103  and the nut  136 , thus increasing or decreasing the ease with which the rocker member  78  and hence the deflection arm  75  can be rotated. 
     Components that extend through the control handle, including, for example, the lead wires  40  and the contraction wire  35  also enter the control handle at the distal end. In the illustrated embodiment of  FIG. 9 , these components extend along the longitudinal axis of the control handle. A protective tubing  152  through which the components extend can be provided, positioned between the two deflection puller members  42  and through a channel  150  form through the width dimension W of the rocker member  78  ( FIG. 11 ). Distal and proximal portions of the channel  150  have indents, e.g., triangular or wedge-shaped,  151  ( FIGS. 9 and 11 ) to allow the rocker member  78  to rotate freely within a predetermined range of angles, e.g., about ±45 degrees of the longitudinal axis of the control handle  16 , without interference by the tubing  152  and the components therethrough. 
     Alternatively, the components extending through the control handle, with the exception of the contraction wire  35 , are routed on an off-axis path  153  diverging from the deflection puller members  42  at entry into the distal end of the control handle  16 . The components thus extend along the periphery of the housing handle, bypassing the rocker member  78 . 
     It is understood that the distance between the distal end of the compression coils  44  and the distal anchor sites of each deflection puller members  42  in the intermediate section  14  determines the curvature of the intermediate section  14  in the direction of the deflection puller members. For example, an arrangement wherein the two deflection puller members  42  are anchored at different distances from the distal ends of the compression coils  44  allows a long reach curve in a first plane and a short reach curve in a plane 90.degree. from the first, i.e., a first curve in one plane generally along the axis of the intermediate section  14  before it is deflected and a second curve distal to the first curve in a plane transverse, and preferably normal to the first plane. The high torque characteristic of the catheter intermediate section  14  reduces the tendency for the deflection in one direction to deform the deflection in the other direction. Suitable deflection control handles and parts thereof for use with such a catheter are described in U.S. patent application Ser. No. 08/924,611, filed Sep. 5, 1997, entitled “Omni-Directional Steerable Catheter”, Ser. No. 09/130,359, filed Aug. 7, 1998, entitled “Bi-Directional Control Handle for Steerable Catheter”, and Ser. No. 09/143,426, filed Aug. 28, 1998, entitled “Bidirectional Steerable Catheter with Bidirectional Control Handle”, the entire disclosures of which are hereby incorporated by reference. 
     For adjusting the mapping assembly  17  by means of a third puller member, e.g., the contraction wire  35 , a distal end of the contraction wire extending between the two deflection puller members  42  within the control handle  16  is anchored in the control handle for actuation by means of a linear control assembly  300  housed in the proximal portion  116  of the control handle. In the illustrated embodiment of  FIG. 23 , the linear control assembly  300  includes a linear control member  302 , a fixed cam  306  whose body  307  supports a rotational member  304 , the combination of which effectuates longitudinal movement of the contraction wire  35  relative to the catheter body  12 , for example, to contract and expand the mapping assembly  17 . In the disclosed embodiment, the linear control assembly  300  is positioned proximal the deflection control assembly  74 , although it is understood that it can be positioned distal the deflection control assembly  74 . 
     With reference to  FIGS. 23-27 , the proximal portion  116  of the control handle  16  in which the linear control assembly is housed has a generally circular cross section of an inner diameter D 1  and an outer diameter D 2 . The cam  306  has a collar  309  and a barrel body  307 . The collar is sized so that it can be received in an inner circumferential groove  260  ( FIG. 15 ) formed in the control handle housing halves  16   a  and  16   b . The collar is affixed therein by glue or the like so the cam is fixed relative to the control handle  16 . The rotational member  304  is mounted on the body  307  of the cam  36  so that it can rotate on the cam in response to linear movement of the control member  302  along a longitudinal axis  310  of the control handle. 
     To convert linear movement of the linear control member  302  into rotational movement of the rotational member  304 , the member  304  has a helical track  305  formed in its outer surface that extends between a distal end and a proximal end of the member  304 . The linear control member  302  has an outer portion  311 , a thinner portion  312 , a wider portion  314 , and a projection  303  ( FIG. 24 ). To couple the control member and the inner rotational member, the projection  303  is received in the track  305  through an opening formed by a recess opening  350  ( FIG. 15 ) formed in each control handle housing halves  16   a ,  16   b  for the thinner portion  312 . The wider portion  314  has a width dimension (better seen in  FIGS. 26 and 27 ) that conforms to a cutout formation  307  ( FIG. 15 ) below the recess opening  350  in the housing halves  16   a ,  16   b  so that the linear control member  302  does not detach from the control handle  16 . The longitudinal dimensions of the recess  350  and  307  which are both greater than the length of the linear control member  302  allow the control member and the control handle to slidably engage each other thus allowing distal and proximal linear movement of the control member along the longitudinal axis, as actuated by user to advance or retract the third puller member. 
     The body  307  of the cam  306  on which the rotational member  304  is supported also has a helical track  332  formed in an outer surface of the body  307 . The track  332  extends between the collar  309  and a proximal end of the body. Riding in the track  332  is a finger  341  of a follower  340  generally situated between the cam  306  and the inner rotational member  304 , whose movement is guided by an axial slot  342  formed in the rotational member  304  as the rotational member is rotated by the linear control member  302  by means of the projection  303  received in the helical track  305 . A distal end of the contraction wire  35  is anchored to the finger  341  so that the follower  340  can move the contraction wire  35  longitudinally relative to the catheter body  12 . 
     As a user moves the control member  302  linearly along the longitudinal axis  310 , the projection  303  rotates the rotational member  304  by means of the track  305  thereon. As the rotational member  304  and its axial slot  342  rotate, so does the follower  340  within the slot  342 , with all three orbiting the longitudinal axis of the cam and the control handle  16 . As the follower  340  orbits, it finger  341  slides in the helical track  332  to move distally or proximally relative to the control handle  16 . As the follower  340  slides distally, the contraction wire  35  is pushed distally to expand the mapping assembly  17 . As the follower  340  slides proximally, the contraction wire is drawn proximally to contract the mapping assembly  17 . Such is a means by which linear movement of the control member  302  is converted to a rotational movement by which the contraction puller member  35  is advanced or retracted within the control handle. Advantageously, the distance the follower  340  can travel along the helical track  332  is not limited to and in fact can be much greater than the length of the cylindrical body  307 , for greater range or degree of motion in the catheter component controlled by the contraction wire  35 . Indeed, the distance the follower  340  can travel (and hence amount by which the contraction wire  35  can be moved) along the cylindrical body  307  depends on the pitch of the helical track  332  (e.g., width of one complete helix turn) and the diameter of the cylindrical body  207 . 
     The collar  309  of the cam  306  has a radial notch  344  through which the contraction wire  35  passes to reach the body  307 . A lip  349  is formed at the proximal end of the body  307  of the cam  306  as a snap-fit feature to retain the rotational member  304  on the body  307 . Axial notches  346  allow deformation or deflection of the proximal end of the cam  307  to facilitate the snap-fit feature. Lead wires and other components (e.g., thermocouple wires, cables, irrigation tubing) extending through the protective tubing  152  can pass through passage  348  of the cam. 
     In an alternate embodiment, the linear control assembly includes a second linear control member  302   b  that diametrically opposes a first linear control member  302   a  on the control handle  16 , as illustrated in  FIGS. 28-31 . Each linear control member has a projection  303   a ,  303   b  that engages a respective one of double helical tracks  305   a  and  305   b  provided on the inner rotational member  304 . As illustrated in  FIG. 32 , the linear control members  302   a ,  302   b  slidably engage the control handle housing halves by means of opposing cutout formations  307   a ,  307   b , respectively, and the projections  303   a ,  303   b  reaches the inner rotational member  304  through recess openings  350   a ,  350   b , respectively. Thus, the user can use either linear control member to expand or contract the mapping assembly, where both linear control members move similarly and contemporaneously in response to actuation of either linear control member by the user. 
     In either of the foregoing embodiments, as a user pushes or pulls on a linear control member, the projection on the linear control member moves distally or proximally in a linear fashion which slides in a helical track on the rotational member to rotate the rotational member. As the rotational member rotates about the cam, its axial slot guides the follower to orbit about the cam. The follower slides in the cam track moving distally or proximally relative to the control handle. As the follower slides distally, the contraction wire is pushed distally, for example, to expand the mapping assembly. As the follower slides proximally, the contraction wire is drawn proximally, for example, to contract the mapping assembly. 
     It is understood that relative sizing of the components of the control assembly is not limited to the illustrated embodiments. Advantageously, the control assembly utilizes minimal space in the control handle for maximizing contraction and expansion of the mapping assembly by converting linear motion of the control member into rotational motion of the inner member which retracts and advances (or releases) the contraction wire in a linear fashion. For either embodiment, a suitable length L of the cam track about the cam can be L=Pi*(D E −D C ) where D E  is the expanded diameter of the generally circular main portion  39  of the mapping assembly  17  and D C  is the contracted diameter of the generally circular main portion  39 . 
     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 Biosense Webster, Inc. (Diamond Bar, Calif.). The distal end of the sheath is guided into one of the chamber, for example, 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  54 . 
     By manipulating and rotating the deflection arm  75  of the deflection control assembly  74  to deflect the intermediate section  14 , the mapping assembly  17  is then inserted into a pulmonary vein or other tubular region (such as the superior vena cava, or inferior vena cava) so that the outer circumference of the generally circular main region  39  of the assembly  17  is in contact with a circumference inside the tubular region. Turning the deflection arm  75  in one direction deflects the intermediate section  14  to that direction. Turning the deflection  75  in the opposite direction deflects the intermediate section  14  to that opposite direction. Tension of the deflection  75  is adjusted by manipulating and rotating the dial  101 . Turning the dial  101  in one direction increases the tension. Turning the dial  101  in the opposition direction decreases the tension. 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  26  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 other tubular structure. By manipulating the linear control member of the control assembly, the assembly  17 , in particular, the generally circular main region  39 , is adjusted to fit the pulmonary vein or other tubular structure. By pulling back on a linear control member, the contraction wire is drawn proximally to tighten and decrease the diameter of the generally circular region  39 . By pushing forward on a linear control member, the contraction wire is pushed distally to release the generally circular region  39  and expands its diameter. 
     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. For example, the catheter can be adapted such that the third puller member advances and retracts another component such as a guide wire or a needle. As understood by one of ordinary skill in the art, the drawings are not necessarily to scale. 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.