Abstract:
A catheter includes a tip electrode with a shell and a support member to provide a plenum chamber. The plug is formed with a U-shaped passage for a safety line to wrap around and secure the support member (with the shell affixed thereto) to the catheter. Additional passages are formed in the plug to accommodate components such as irrigation tubing, lead wire and thermocouple wire pair. A method of manufacture provides distal installation and/or anchoring of the safety line, lead wire and thermocouple wire pair in the support member prior to sealing the support member and mounting the shell.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 13/736,020 filed Jan. 7, 2013, issued as U.S. Pat. No. 9,174,023, the entire content of which is incorporated herein by reference. 
     
    
     FIELD OF INVENTION 
       [0002]    The present invention relates to catheters, particular catheters with a deflectable portion and a control handle to control deflection. 
       BACKGROUND OF INVENTION 
       [0003]    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 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. 
         [0004]    A typical mapping or ablation catheter has an elongated catheter body, an intermediate deflectable section, a distal section carrying one or more electrodes, and a control handle in which the proximal end of at least one puller wire is anchored. The puller wire extends distally through the catheter body and at least through the intermediate deflectable section. A distal end of the puller wire is typically anchored at or near a junction of the deflectable section and the distal section. A compression coil surrounding the puller wire is generally provided through the catheter body, where a distal end of the compression coil defines an initiation location of the desired deflection. A protective tubing around the puller wire generally provided distal of the compression coil to protect the outer tubing of the catheter from being cut by the puller wire during deflection. 
         [0005]    Unidirectional catheters use a single puller wire. Control handles for unidirectional catheter include control handles using a piston that is housed in a handle housing and longitudinally movable relative thereto for actuating the puller wire in achieving a desired deflection. Because the patient&#39;s heart is active with blood flow and moving walls and chambers, the catheter is subjected to forces that may cause the catheter to change or lose the deflection without an operator&#39;s constant attention and manipulation. Thus, the piston may have a friction-inducing member, for example, an O-ring, situated between the piston and the handle housing to maintain a desired deflection and prevent the piston from sliding or moving under these forces. However, the O-ring may not consistently provide sufficient friction to hold the piston and maintain the desired deflection. 
         [0006]    Accordingly, it is desirable to provide a unidirectional catheter control handle with a tension mechanism that can releasably lock the piston in a particular position, and allow repositioning of the piston to a different position and adjusting of the amount of force needed to reposition the piston. Moreover, it is desirable that the mechanism allow control of the tension of deflection for providing a user with an enhanced ability to accurately position the catheter. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a unidirectional catheter with an improved control handle having a tension adjustment assembly enabling the catheter to be releasably locked in a desired deflection and allowing adjustment of the catheter&#39;s resistance to deflection. 
         [0008]    In one embodiment, the catheter includes a flexible tubing, and a control handle having a housing and a piston in a telescopic configuration, where the piston has a thumb control and the piston is longitudinally slidable relative to the housing by a user via the thumb control for deflecting the tubing. Advantageously, the control handle includes a tension adjustment assembly that provides a force member adapted for applying a force on the piston, and a knob rotationally coupled to the force member, where the knob is adapted for rotation by the user to adjust the force applied on the piston by the force member. The force includes contact, pressure and/or friction between the piston and the housing of the control handle and allows the piston to be releasably locked in a desired position relative to the housing, repositioned relative to the housing and adjustment of the ease by which the piston can be moved relative to the housing. The tension adjustment assembly may also include a guide which limits the range of motion of the knob so as to prevent damage to the piston and/or housing, or disassembly or detachment of the tension adjustment assembly. 
         [0009]    In a more detailed embodiment, the force member includes a set screw which extends through an axial bore formed in the knob, where a distal end of the set screw extends through a threaded bore formed in the housing so that the distal end makes adjustable contact with the piston to apply the force. The distal tip may have a nonslip surface for contact with the housing. 
         [0010]    The knob is configured for rotation in one direction to increase the force applied by the set screw on the piston and in an opposition direction to decrease the force applied by the set screw on the piston, where increasing the frictional engagement locks the piston and the housing in a desired position and decreasing the frictional engagement unlocks the piston and the housing and allows repositioning of the piston and the housing relative to each other. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0011]    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: 
           [0012]      FIG. 1  is a perspective view of a catheter in accordance with an embodiment of the present invention. 
           [0013]      FIG. 2  is a side cross-sectional view of the catheter of  FIG. 1 , including a junction between a catheter body and an intermediate deflectable section. 
           [0014]      FIG. 2A  is an end cross-sectional view of the intermediate deflectable section of  FIG. 2 , taken along line A-A. 
           [0015]      FIG. 3  is a side cross-sectional view of the catheter of  FIG. 1 , including a junction between the intermediate deflectable section and a distal section. 
           [0016]      FIG. 3A  is a side cross-sectional view of the catheter of  FIG. 1 , including a tip electrode. 
           [0017]      FIG. 4  is a side cross-sectional view of the catheter handle of  FIG. 1 . 
           [0018]      FIG. 5  is an exploded perspective view of a tension adjustment assembly in accordance with an embodiment of the present invention, including a guide plate. 
           [0019]      FIG. 6  is a side cross-sectional view of an tension adjustment assembly. 
           [0020]      FIG. 7  is an exploded perspective view of a tension control knob of the assembly of  FIGS. 5 and 6 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]      FIG. 1  illustrates an embodiment of a catheter  10  with an elongated catheter body  12 , an deflectable intermediate section  14 , a distal section  15  with a tip electrode  17  and an improved control handle  16  employing a piston  54  housed in a handle housing for unidirectional deflection that advantageously provides a tension adjusting mechanism  55  that allows an operator to releasably lock the piston in a particular position relative to the handle housing, and allow repositioning of the piston to a different position and adjusting of the amount of force needed to reposition the piston. As such, the control handle provides a user with an enhanced ability to accurately position the catheter within the patient&#39;s body. 
         [0022]    With reference to  FIGS. 1 and 2 , the catheter body  12  comprises an elongated tubular construction having a single, axial or central lumen  18 . 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. 
         [0023]    The outer diameter of the catheter body  12  is not critical, but is preferably no more than about 8 french, more preferably 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 puller wire, lead wires, and any other desired wires, cables or tubings. If desired, the inner surface of the outer wall  20  is lined with a stiffening tube  22  to provide improved torsional stability. A disclosed embodiment, the 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. 
         [0024]    Distal ends of the stiffening tube  22  and the outer wall  20  are fixedly attached near the distal end of the catheter body  12  by forming a glue joint  23  with polyurethane glue or the like. A second glue joint (not shown) is formed between proximal ends of the stiffening tube  20  and outer wall  22  using a slower drying but stronger glue, e.g., polyurethane. 
         [0025]    Components that extend between the control handle  16  and the deflectable section  14  pass through the central lumen  18  of the catheter body  12 . These components include lead wires  40  for the tip electrode  17  and ring electrodes  21  carried on the distal section  15 , an irrigation tubing  38  for delivering fluid to the tip electrode, a cable  74  for an electromagnetic position/location sensor  34  carried in the distal section  15 , puller wire  42  for deflecting the intermediate section  14 , and a pair of thermocouple wires  41 ,  43  to sense temperature at the distal section  15 . 
         [0026]    Illustrated in  FIGS. 2 and 2A  is an embodiment of the intermediate section  14  which comprises a short section of tubing  19 . The tubing also has a braided mesh construction but with multiple off-axis lumens, for example lumens  26 ,  27  and  28 . The first lumen  26  carries a puller wire  42  for unidirectional deflection of the intermediate section. The second lumen  27  carries the lead wires  40 , the thermocouple wires  41  and  43 , and the sensor cable  74 . The third lumen  28  carries the irrigation tubing  38 . 
         [0027]    The tubing  19  of the intermediate section  14  is made of a suitable non-toxic material that is 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 size of each lumen is not critical, but is sufficient to house the respective components extending therethrough. 
         [0028]    A means for attaching the catheter body  12  to the intermediate section  14  is illustrated in  FIGS. 2 and 2A . The proximal end of the intermediate section  14  comprises an outer circumferential notch  25  that receives an inner surface of the outer wall  20  of the catheter body  12 . The intermediate section  14  and catheter body  12  are attached by glue or the like. 
         [0029]    If desired, a spacer (not shown) can be located within the catheter body between the distal end of the stiffening tube (if provided) and the proximal end of the intermediate section. The spacer provides a transition in flexibility at the junction of the catheter body and intermediate section, 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. 
         [0030]    The puller wire  42  is preferably coated with Teflon®. The puller wire can be made of any suitable metal, such as stainless steel or Nitinol and the Teflon coating imparts lubricity to the puller wire. The puller wire preferably has a diameter ranging from about 0.006 to about 0.010 inch. 
         [0031]    The portion of the puller wire in the catheter body  12  passes through a compression coil  35  in surrounding relation thereto. The compression coil  35  extends from the proximal end of the catheter body  12  to at or near the proximal end of the intermediate section  14 . The compression coil is made of any suitable metal, preferably stainless steel, and are tightly wound on itself to provide flexibility, i.e., bending, but to resist compression. The inner diameter of the compression coil is preferably slightly larger than the diameter of the puller wire. Within the catheter body  12 , the outer surface of the compression coil  35  is also covered by a flexible, non-conductive sheath  39 , e.g., made of polyimide tubing. The portion of the puller wires distal of the compression coil  35  may extend through a protective plastic sheath  37 , e.g., of TEFLON®, to prevent the puller wire from cutting into the tubing  19  of the intermediate section  14  during deflection. 
         [0032]    A proximal end of the puller wire  42  is anchored in the control handle  16 , as described further below. A distal end of the puller wire is anchored in the distal section  15 , for example, by a T-bar  44  as shown in  FIG. 3 . 
         [0033]    As shown in  FIGS. 3 and 3A , the distal section  15  comprises a tubing  24  extending between the deflectable intermediate section  14  and the tip electrode  17 . The tubing  24  has a central lumen  48  which houses the sensor  34  and allows components, including the tip and ring electrode lead wires  40 T and  40 R, the thermocouple wire pair  41  and  43 , irrigation tubing  38  and sensor cable  74 , extending to the tip electrode  17  to reorient themselves. Mounted on the tubing  24  is at least one ring electrode  21 . 
         [0034]    The tip electrode  17  is received in a distal end of the tubing  24 . On a proximal surface of the tip electrode, blind holes  60  and  62  are formed to receive distal ends of the tip electrode lead wire  40 T and the thermocouple wires  41  and  43 , respectively. Receiving a distal end of the irrigation tubing  38  is an axial passage  66  formed in the tip electrode  17 . The axial passage  66  connect with transverse branches  68  and fluid ports  69  that pass fluid from the irrigation tubing to outside the tip electrode. 
         [0035]    With reference to  FIG. 4 , longitudinal movement of the puller wire  42  relative to the catheter body  12 , which results in deflection of the tip section  12 , is accomplished by suitable manipulation of the control handle  16 . The distal end of the control handle  16  comprises a piston  54  that is telescopically movable relative to a control handle housing or barrel  80 . An outer surface  82  of the piston is generally surrounded by and in slidable contact with an inner surface  84  of the barrel  80 . The proximal end of the catheter body  12  is connected to the piston  54  by means of a shrink sleeve  31 . 
         [0036]    The piston  54  has a thumb control  56  that is distal and outside of the housing  80  and accessible to a user grasping the barrel  80  to move distally or proximally, for example, with his thumb, relative to the housing for manipulating the puller wire  42 . The surfaces  82  and  84  slide against each other as the piston is moved longitudinally relative to the barrel  80  by the user via the thumb control  56 . An O-ring  86  mounted on the piston and sandwiched between the surfaces  82  and  84  provides friction to provide more control and “feel” in the movement of the piston  54  relative to the barrel  80 . However, in accordance with a feature of the present invention, the control handle includes a tension adjustment assembly  90  that allows the user to releasably lock the piston in place, reposition of the piston, and adjust the amount of friction between the piston and the barrel  80  in controlling the amount of force needed to move the piston  54 . 
         [0037]    With reference to  FIGS. 5 and 6 , the tension adjustment assembly  90  includes a force or contact member  92  adapted for contact with the piston  54  and an adjustable micro-tension control knob  94  configured to adjust the amount of contact, pressure and/or friction (used interchangeably herein) exerted by the contacting member on the piston. In the illustrated embodiment, the knob has a circular cross section and the member  92  includes a set screw  96  with a nonslip, friction-inducing tip  98 , e.g., of low durometer plastic, that is received in a center axial bore  100  of the knob  94 . The screw  96  and the knob  94  are rotationally coupled to each other, for example, by coupling pins  102  ( FIG. 7 ) that contact and fixedly engage the body of the screw  96  through threaded radial bores  106  formed in the knob  94 . The screw and knob may also be rotationally coupled by glue or sonic welding. The distal tip  98  of the screw is received in a threaded bore  108  formed in a raised surface region  115  of the barrel  80 . 
         [0038]    Generally surrounding the bore  108  is at least one rotational travel path guide  110 . In the illustrated embodiment, there are a pair of diametrically opposing, recessed semi-circular tracks. Sliding in the guides  110  are diametrically opposing projections or pins  112  extending from an inner adjacent surface of the knob  94 . The guides may be formed in the raised region  115  of the barrel  80  ( FIG. 6 ). Alternatively, the assembly  90  may include a circular guide plate  117  ( FIG. 5 ) with the guides  110  formed thereon and a center threaded bore  109  aligned with the bore  108 . The guide plate is affixed to the outer surface  82  of the barrel  80  and sandwiched between the barrel  80  and the knob  94 . 
         [0039]    In use, the user manipulates the thumb control  56  by moving it distally or proximally relative to the barrel  80  to achieve the desired deflection in the catheter. To lock, release and/or allow for more “feel” or greater tension in movability and adjustability of the thumb control  56  and the piston  54 , the user can vary the tension by rotating the knob  94 . By rotating the knob  94 , the set screw  96  rotationally coupled thereto is either advanced into or withdrawn out of the bore  108  in the barrel for applying greater or lesser contact, pressure and/or friction forces by its distal tip  98  onto the outer surface of the barrel  80 . By loosening the knob  94 , movement of the piston  54  relative to the barrel  80  is increased. By tightening the knob  94 , movement of the piston  54  relative to the barrel is decreased. Maximum and minimum levels of the forces are advantageously limited by ends  114  of guides  100  which prevent the pins  112  and hence the knob  94  from being rotated in either the clockwise or counterclockwise direction beyond positions that would damage the piston or allow disassembly of the assembly  90 . In the illustrated embodiment, each guide  110  spans about 160 degrees. In reaching a maximum tightness as limited by the guides  110 , the piston is locked in place to maintain a desired deflection. In reaching a maximum looseness as limited by the guides  110 , the piston is easily movable without the set screw  96  or the knob  94  disengaging entirely from the barrel  80 . Outer circumferential surface  116  of the knob may be ribbed or otherwise textured for providing a more tactile surface for the user. 
         [0040]    In the illustrated embodiment, the tension adjustment assembly  90  is positioned closer to the distal end of the barrel  80 . However, it is understood that the assembly  90  may be positioned anywhere on the barrel  80  so long as the contact member  92  or set screw  96  is able to come in and out of contact with the outer surface  82  of the barrel. 
         [0041]    As show in  FIG. 4 , the puller wire  42 , the lead wires  40  for the tip electrode  17  and any ring electrodes, and the electromagnetic sensor cable  74  extend through the piston  54 . The puller wire  42  is anchored to an anchor pin  57  located proximal to the piston  54 . The lead wires  40  and electromagnetic sensor cable  74  extend through a first tunnel  58 , located near the side of the control handle  16 . The electromagnetic sensor cable  74  connects to the circuit board  64  in the proximal end of the control handle. Wires  73  connect the circuit board  64  to a computer and imaging monitor (not shown). 
         [0042]    Within the piston  54 , the electromagnetic sensor cable  74  and lead wires  40  are situated within a transfer tube  77   a,  and the puller wire  42  is situated within another transfer tube  77   b  to allow longitudinal movement of the wires and cable near the glue joint  53 . 
         [0043]    The lead wires  40  pass through the lumen  28  ( FIGS. 2 and 2A ) of the tubing  19  of the deflectable intermediate section  14  and the central lumen  18  of the catheter body  12 . The portion of the lead wires extending through the central lumen  18  of the catheter body  12 , and proximal end of the lumen  27  may be enclosed within a protective sheath (not shown), which can be made of any suitable material, preferably polyimide. The protective sheath is anchored at its distal end to the proximal end of the intermediate section  14  by gluing it in the lumen  27  with polyurethane glue or the like. Each electrode lead wire has its proximal end terminating in a connector at the proximal end of the control handle  16 . 
         [0044]    The preceding description has been presented with reference to certain exemplary embodiments of the invention. Workers skilled in the art and technology to which this invention pertains will appreciate that alterations and changes to the described structure may be practiced without meaningfully departing from the principal, spirit and scope of this invention. It is understood that 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. Rather, it should be read as consistent with and as support for the following claims which are to have their fullest and fairest scope.