Abstract:
A catheter that is particularly useful for mapping electrical activity in the heart of a patient is provided. The catheter comprises an elongated catheter body having a lumen extending longitudinally therethrough. A control handle is attached to the proximal end of the catheter body and includes first and second members that are moveable relative to each other. The second member is attached to the catheter body. An inner member is slidably mounted in the lumen of the catheter body. The inner member comprises an elongated stiffening member that is surrounded by and connected to a non-conductive covering having a free distal end on which is mounted one or more electrodes. The proximal end of the inner member is attached to the first member of the control handle. Longitudinal movement of the first member relative to the second member results in longitudinal movement of the inner member relative to the catheter body to cause the inner member to extend out of and retract into the catheter body.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S)  
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 60/426,834, filed Nov. 15, 2003, the entire disclosure of which is incorporated herein by reference. 
     
    
     
       BACKGROUND  
         [0002]    Electrophysiology catheters are commonly used for mapping electrical activity in a heart. By mapping the electrical activity in the heart, one can detect ectopic sites of electrical activation or other electrical activation pathways that contribute to heart malfunctions. This type of information may then allow a cardiologist to intervene and destroy the malfunctioning heart tissues. Such destruction of heart tissue is referred to as ablation, which is a rapidly growing field within electrophysiology and obviates the need for maximally invasive open heart surgery.  
           [0003]    Such electrophysiology mapping catheters typically have an elongated flexible body with a distal end that carries one or more electrodes that are used to map or collect electrical information about the electrical activity in the heart. The distal end can be deflectable to assist the user in properly positioning the catheter for mapping in a desired location. Typically, such catheters can be deflected to form a single curve. It is desirable to have a catheter that can be deflective to form a variety of curves to thereby map an entire region where a single curve may not be sufficient.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention is directed to an improved catheter that is particularly useful for mapping electrical activity in a heart of a patient and that allows the user to vary curve preferences as well as the number of electrodes to be used to map a particular area of tissue.  
           [0005]    In one embodiment, the invention is directed to a catheter comprising an elongated catheter body having a proximal end, a distal end and a lumen extending longitudinally therethrough. A control handle is attached to the proximal end of the catheter body. The control handle includes a first member, such as housing, that is moveable relative to a second member, such as a piston slidably mounted in the housing. The catheter body is attached to the second member.  
           [0006]    An inner member is slidably mounted in the lumen of the catheter body. The inner member comprises an elongated stiffening member, having proximal and distal ends, that is surrounded by and connected to a non-conductive covering. The non-conductive covering has a free distal end on which is mounted one or more electrodes. The proximal end of the inner member is attached to the first member of the control handle. Longitudinal movement of the first member relative to the second member results in longitudinal movement of the inner member relative to the catheter body to cause the inner member to extend out of and retract into the catheter body. 
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0007]    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:  
         [0008]    [0008]FIG. 1 is a perspective view of a catheter according to the invention.  
         [0009]    [0009]FIG. 2 is an end cross-sectional view of the catheter body of the catheter of FIG. 1 taken along line  2 - 2 .  
         [0010]    [0010]FIG. 3 is an end cross-sectional view of the inner member of the catheter of FIG. 1 taken along line  3 - 3 .  
         [0011]    [0011]FIG. 4 is a side cross-sectional view of the control handle of the catheter of FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0012]    The invention is directed to a telescoping catheter having an extendable and retractable mapping assembly at the distal end of the catheter that is deflectable. As shown in FIG. 1, the catheter comprises an elongated catheter body  12  having proximal and distal ends, an elongated telescoping inner member  14  extending through the catheter body, and a control handle  16  at the proximal end of the catheter body. The catheter body  12  comprises an elongated tubular construction having a single, axial or central lumen  15 , as shown in FIG. 2, but can optionally have multiple lumens along all or part of its length 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 of the catheter body  12  comprises an outer wall  18  made of polyurethane or PEBAX® (polyether block amide). The outer wall  18  preferably comprises an imbedded braided mesh of stainless steel or the like, as is generally known in the art, to increase torsional stiffness of the catheter body  12  so that, when the control handle  16  is rotated, the distal end of the catheter body  12  will rotate in a corresponding manner.  
         [0013]    The length of the catheter body  12  is not critical, but preferably ranges from about 90 cm to about 120 cm, and more preferably is about 110 cm. The outer diameter of the catheter body  12  is also not critical, but is preferably no more than about 8 french, more preferably about 7 french. Likewise, the thickness of the outer wall  18  is not critical, but is preferably thin enough so that the central lumen  15  can accommodate all necessary wires and other components extending through the catheter body  12 .  
         [0014]    In the depicted embodiment, two ring electrodes  17  are mounted, preferably evenly-spaced, along the distal end of the catheter body  12 . As would be recognized by one skilled in the art, the number and arrangement of the electrodes on the catheter body can vary as desired, or the electrodes can be eliminated altogether. Each ring electrode  17  is electrically connected to an electrode lead wire  19 , which in turn is electrically connected to a connector  34  at the proximal end of the catheter, which is connected to an appropriate mapping or monitoring system (not shown). Each electrode lead wire  19  extends from the connector  34 , through the control handle  16 , and into the central lumen  15  of the catheter body  12  where it is attached to its corresponding ring electrode  17 . Each lead wire  19 , which includes a non-conductive coating over almost all of its length, is attached to its corresponding ring electrode  17  by any suitable method.  
         [0015]    The inner member  14  is slidably mounted within the central lumen  15  of the catheter body  12 . As best shown in FIG. 3, the inner member  14  comprises an elongated stiffening member  20  surrounded by a flexible non-conductive cover  22 . The stiffening member  20  preferably comprises a superelastic material, for example a nickel-titanium alloy such as nitinol, but can comprise any other suitable material, such as stainless steel or plastic. The non-conductive cover  22  preferably comprises a biocompatible plastic tubing, such as a polyurethane or polyimide tubing. In the depicted embodiment, the non-conductive cover  22  has an outer wall  24  with a single lumen  26  extending therethrough, but could alternatively include multiple lumens. The non-conductive cover  22 , and thus the inner member  14 , has a free distal end, i.e., a distal end that is not connected or attached to any other part of the inner member, to the catheter body, or to any other external structure that confines movement of the distal end.  
         [0016]    In the depicted embodiment, the distal end of the inner member  14  has an atraumatic tip comprising a plastic cap  28 , preferably made of polyurethane. The plastic cap  28  is glued or otherwise fixedly attached to the distal end of the inner member  14 . Other atraumatic tip designs could be used in connection with the invention, or the use of an atraumatic tip can be eliminated.  
         [0017]    The inner member  14  carries one or more electrodes along its distal end. In the depicted embodiment, twelve ring electrodes  30  are mounted, preferably evenly-spaced, along the distal end of the non-conductive cover  22 . As would be recognized by one skilled in the art, the number and arrangement of the electrodes on the inner member can vary as desired. For example, the inner member  14  could carry a tip electrode (not shown) on the distal end of the spine in place of the plastic cap  28 . Each ring electrode  30  has a length preferably up to about 2 mm, more preferably from about 0.5 mm to about 1 mm. The distance between the ring electrodes  28  preferably ranges from about 1 mm to about 10 mm, more preferably from about 2 mm to about 5 mm. Preferably the inner member  14  carries from 2 to about 20 electrodes, more preferably from 3 to about 15 electrodes.  
         [0018]    Each ring electrode  30  is electrically connected to an electrode lead wire  32 , which in turn is electrically connected to the connector  34 , which is connected to an appropriate mapping or monitoring system (not shown). In the depicted embodiment, the inner member electrode lead wires  32  are connected to the same connector as the catheter body electrode lead wires  19 , but could also be connected to a different connector depending on the desired application. Each electrode lead wire  32  extends from the connector  34 , through the control handle  16 , and into the non-conductive cover  22  of the inner member  14  where it is attached to its corresponding ring electrode  30 . Each lead wire  32 , which includes a non-conductive coating over almost all of its length, is attached to its corresponding ring electrode  30  by any suitable method.  
         [0019]    A preferred method for attaching a lead wire  19  or  32  to a ring electrode  17  or  30  involves first making a small hole through the outer wall of the catheter body  12  or non-conductive cover  22 . Such a hole can be created, for example, by inserting a needle through the outer wall and heating the needle sufficiently to form a permanent hole. The lead wire  19  or  32  is then drawn through the hole by using a microhook or the like. The end of the lead wire  19  or  32  is then stripped of any coating and welded to the underside of the corresponding ring electrode  17  or  30 , which is then slid into position over the hole and fixed in place with polyurethane glue or the like. Alternatively, each ring electrode  19  or  30  may be formed by wrapping the lead wire  17  or  32  around the catheter body  12  or non-conductive cover  22  a number of times and stripping the lead wire of its own non-conductive coating on its outwardly facing surfaces. In such an instance, the lead wire functions as a ring electrode.  
         [0020]    The inner member  14  is moveable between a retracted position, where the entire inner member is contained within the central lumen  15  of the catheter body  12 , and a fully extended position, where all of the electrodes  30  mounted on the inner member extend beyond the distal end of the catheter body. The length of the exposed portion of the inner member  14  when in the fully extended position preferably ranges from about 10 mm to about 200 mm. The inner member  14  can also be moved to one or more intermediate extended positions where the distal end of the inner member  14  extends beyond the distal end of the catheter body  12 , but one or more of the electrodes  30  are still contained within the central lumen  15  of the catheter body. To affect such movement, the proximal end of the stiffening member  20  is attached to the control handle  16 , as discussed in more detail below.  
         [0021]    In the depicted embodiment, the distal end of the stiffening member  20  is attached to the distal end of the inner member  14 , and indirectly to the distal end of the non-conductive cover  22 , by being glued or otherwise attached to the plastic cap  22 . The stiffening member  20  can be attached, directly or indirectly, to the non-conductive cover  22  in any other manner and at any other position along the length of the inner member  14 . However, it is currently preferred that the stiffening member  20  be attached to the non-conductive cover  22  closer to the distal end of the inner member  14  to permit the user to have better control when extending and retracting the inner member.  
         [0022]    In the depicted embodiment, the non-conductive cover  22  extends the full length of the catheter body  12  with its proximal end in the control handle  16 . However, if desired, the non-conductive cover  22  can terminate at its proximal end at any position within the catheter body  12 . The non-conductive cover  22  should be sufficiently long so that, when the inner member  14  is in its fully extended position, at least a portion of the non-conductive cover is maintained within the catheter body  12 .  
         [0023]    Within the catheter body  12 , the inner member  14  extends through a sleeve  38 , preferably made of plastic, such as nylon. The sleeve  38  serves as a lumen for the inner member  14  within the catheter body  12 . In particular, the sleeve  38  protects the inner member  14  from interfering or getting tangled with the lead wires  19  that extend through the catheter body  12  when the inner member  14  is being extended or retracted.  
         [0024]    Additionally, a mechanism is provided for deflecting the distal end of the inner member  14 . Specifically, a puller wire  36  extends through the non-conductive cover  22  with a distal end anchored at or near the distal end of the inner member  14  and a proximal end anchored to the control handle  16 , as described further below. The puller wire  36  is made of any suitable metal, such as stainless steel or Nitinol, and is preferably coated with Teflon® or the like to impart lubricity to the puller wire. The puller wire  36  preferably has a diameter ranging from about 0.006 to about 0.010 inches.  
         [0025]    A preferred mechanism for anchoring the puller wire  36  to the inner member  14  comprises a T-bar anchor  39  anchored within the plastic cap  28  by glue or the like. If the inner member  14  includes multiple lumens, the T-bar anchor  39  can be anchored to the plastic cap  28  as generally described in U.S. Pat. Nos. 5,893,885 and 6,066,125, the entire disclosures of which are incorporated herein by reference. If the inner member  14  carries a tip electrode, the puller wire  36  can be anchored in the tip electrode, as also described in U.S. Pat. No. 6,066,125. Alternatively, the puller wire  36  can be anchored to the side of the inner member  14 , as generally described in U.S. Pat. No. 6,123,699, the entire disclosure of which is incorporated herein by reference. Other arrangements for anchoring a puller wire  36  to the distal end of the inner member  14  are included within the scope of the invention. If desired, a compression coil (not shown) may be provided in surrounding relation to the puller wire  36  within the catheter body  12 , as described in U.S. Pat. No. 6,066,125.  
         [0026]    Longitudinal movement of the stiffening member  20  to affect extension and retraction of the inner member  14  is accomplished by suitable manipulation of the control handle  16 . Similarly, longitudinal movement of the puller wire  36  relative to the catheter body  12 , which results in deflection of the inner member  14 , is accomplished by suitable manipulation of the control handle  16 .  
         [0027]    As shown in FIGS. 1 and 4, a preferred control handle comprises a generally cylindrical housing  40  having a piston chamber  42  at its distal end. A generally cylindrical piston  44  is disposed within and generally coaxial with the piston chamber  42 . The piston  44  includes a circumferential O-ring notch  46  that carries an O-ring  48  to provide a snug, watertight fit between the piston and the wall of the piston chamber  42 . The piston  44  has an axial bore  50  along its length. The diameter of the axial bore  50  is approximately the same as the outer diameter of the catheter body  12 . The proximal end of the catheter body  12  extends into the axial bore  50  and is fixedly attached, for example, by glue, to the piston  44 . The stiffening member  20 , puller wire  36 , and electrode lead wires  19  and  32  extend from the inner member  14  or catheter body  12 , through the axial bore  50  of the piston  44  and into the control handle  16 .  
         [0028]    The distal end of the piston  44  extends beyond the distal end of the housing  40  so that it can be manually controlled by the user. An annular thumb control  52  is attached at or near the distal end of the piston  44  to facilitate lengthwise movement of the piston relative to the housing  40 .  
         [0029]    For longitudinal movement of the stiffening member  20 , the housing includes a longitudinal slot  56  extending therethrough. A slider  58  is slidably mounted in the longitudinal slot  56 , as best shown in FIG. 1. The proximal end of the stiffening member  20  is anchored to the portion of the slider  58  that is contained within the handle housing  40  by any suitable method. A suitable method for anchoring the stiffening member  20  to the slider  58  involves use of a short stainless steel tubing  60  or the like mounted on the proximal end of the stiffening member. The slider  58  includes an opening  62  for receiving the stainless steel tubing  60  and a channel  64  distal to the opening having a size that permits the stiffening member  20  to pass therethrough but that prevents the stainless steel tubing from passing therethrough. Other mechanisms for anchoring the stiffening member  20  to the slider  58  are within the scope of the invention.  
         [0030]    For longitudinal movement of the puller wire  36 , the puller wire is anchored to the housing  40  by any suitable method. In the depicted embodiment, the puller wire  36  is anchored to the housing by means of an anchor  54  that extends into a transverse hole in the housing proximal to the piston chamber  42 . Such a design is described in more detail in U.S. Pat. No. 5,383,923, the entire disclosure of which is incorporated herein by reference. In use, the distal end of the inner member  14 , once moved to an extended position, can be curved or bent by moving the piston  44  distally out of the piston chamber  42  by pushing outwardly on the thumb control  52 .  
         [0031]    The precise control handle mechanisms used for deflection of the puller wire  36  and for extension of the inner member  14  can be modified as desired. For example, the slider  58  could instead be used for manipulation of the puller wire  36 , and the piston  42  can be used for manipulation of the stiffening member  20 . Other control handles capable of manipulating a plurality of wires can also be used in connection with the invention. Examples of such handles are disclosed in U.S. Pat. No. 6,066,125 and U.S. patent application Ser. No. 09/710,210, entitled “Deflectable Catheter with Modifiable Handle,” the disclosures of which are incorporated herein by reference.  
         [0032]    If desired, a catheter body puller wire (not shown) can also be provided for deflection of the distal end of the catheter body  12 . With such a design, the catheter puller wire is anchored at its distal end to the distal end of the catheter body, as generally described in U.S. Pat. No. 6,123,699, and is anchored at its proximal end to the control handle  16 . To manipulate the catheter body puller wire, the control handle would contain an additional deflection mechanism, such as an additional slider (not shown) in a separate slot. If desired, the distal end of the catheter body  12  can comprise a piece of tubing (not shown) that is more flexible than the rest of the catheter body and that contains an off-axis lumen (not shown) into which the distal end of the catheter puller wire extends, as generally described in U.S. Pat. No. 6,123,699.  
         [0033]    If desired, the inner member  14  and/or the distal end of the catheter body  12  can also include one or more location sensors (not shown), such as an electromagnetic location sensor, for conveying locational information about the electrodes on the inner member and/or catheter body. Use and design of such location sensors are described in more detail in U.S. application Ser. No. 10/040,932, entitled “Catheter Having Multiple Spines Each Having Electrical Mapping and Location Sensing Capabilities,” the disclosure of which is incorporated herein by reference.  
         [0034]    The preceding description has been presented with references to presently preferred embodiments of the invention. Persons skilled in the art and technology to which this invention pertains will appreciate that alterations and changes in the described structures can be practiced without meaningfully departing from the principle, spirit and scope of this invention. Accordingly, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.