Patent Publication Number: US-2021187241-A1

Title: Expandable Assembly Catheter

Description:
FIELD OF THE INVENTION 
     The present invention relates to medical equipment, and in particular, but not exclusively, to expandable assembly catheters. 
     BACKGROUND 
     A wide range of medical procedures involve placing probes, such as catheters, within a patient&#39;s body. Location sensing systems have been developed for tracking such probes. Magnetic location sensing is one of the methods known in the art. In magnetic location sensing, magnetic field generators are typically placed at known locations external to the patient. A magnetic field sensor within the distal end of the probe generates electrical signals in response to these magnetic fields, which are processed to determine the coordinate locations of the distal end of the probe. These methods and systems are described in U.S. Pat. Nos. 5,391,199, 6,690,963, 6,484,118, 6,239,724, 6,618,612 and 6,332,089, in PCT International Publication No. WO 1996/005768, and in U.S. Patent Application Publications Nos. 2002/006455 and 2003/0120150 and 2004/0068178. Locations may also be tracked using impedance or current based systems. 
     One medical procedure in which these types of probes or catheters have proved extremely useful is in the treatment of cardiac arrhythmias. Cardiac arrhythmias and atrial fibrillation in particular, persist as common and dangerous medical ailments, especially in the aging population. 
     Diagnosis and treatment of cardiac arrhythmias include mapping the electrical properties of heart tissue, especially the endocardium and the heart volume, and selectively ablating cardiac tissue by application of energy. Such ablation can cease or modify the propagation of unwanted electrical signals from one portion of the heart to another. The ablation process destroys the unwanted electrical pathways by formation of non-conducting lesions. Various energy delivery modalities have been disclosed for forming lesions, and include use of microwave, laser and more commonly, radiofrequency energies to create conduction blocks along the cardiac tissue wall. In a two-step procedure, mapping followed by ablation, electrical activity at points within the heart is typically sensed and measured by advancing a catheter containing one or more electrical sensors into the heart, and acquiring data at a multiplicity of points. These data are then utilized to select the endocardial target areas at which the ablation is to be performed. 
     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 vein, and then guided into the chamber of the heart of concern. A typical ablation procedure involves the insertion of a catheter having a one or more electrodes at its distal end into a heart chamber. A reference electrode may be provided, generally taped to the skin of the patient or by means of a second catheter that is positioned in or near the heart. RF (radio frequency) current is applied to the tip electrode(s) of the ablating catheter, and current flows through the media that surrounds it, i.e., blood and tissue, toward the reference electrode. 
     The distribution of current depends on the amount of electrode surface in contact with the tissue as compared to blood, which has a higher conductivity than the tissue. Heating of the tissue occurs due to its electrical resistance. The tissue is heated sufficiently to cause cellular destruction in the cardiac tissue resulting in formation of a lesion within the cardiac tissue which is electrically non-conductive. 
     US Patent Publication 2013/0253298 of Harley, et al., describes a multi electrode catheter for non-contact mapping of the heart having independent articulation and deployment features. 
     US Patent Publication 2012/0239028 of Wallace, et al., describes in one embodiment, a device including an expandable support member having a first portion and a second portion. The first portion is adapted to have a smaller expansion index than the second portion. A therapeutic or diagnostic instrument is supported, at least in part, by the expandable support member first portion. In another embodiment, the support member is adapted for non-uniform expansion of the first and second portions. There are also described methods of forming therapeutic devices. There are also described methods of providing therapy to tissue in a body by positioning a device in proximity to tissue in a body selected to receive therapy. Next, the expandable support member second portion is expanded until the instrument is at a therapeutic position relative to the tissue in a body selected to receive therapy. Thereafter, therapy or diagnosis is provided to the selected tissue using the device. 
     U.S. Pat. 5,823,189 to Kordis describes an electrode support structure has at least two spline leaves, each comprising an opposed pair of spline elements connected by a center web. Each web has a hole through which a pin assembly extends to join the webs of the spline leaves in a mutually stacked relationship. The spline elements radiate from the pin assembly in a circumferentially spaced relationship for carrying one or more electrodes. A hub member is over-molded about the pin assembly. 
     U.S. Pat. No. 8,644,902 to Kordis, et al., describes a method for sensing multiple local electric voltages from endocardial surface of a heart, and includes providing a system for sensing multiple local electric voltages from endocardial surface of a heart, including: a first elongate tubular member having a lumen, a proximal end and a distal end; a basket assembly including: a plurality of flexible splines for guiding a plurality of exposed electrodes, the splines having proximal portions, distal portions and medial portions therein between, wherein the electrodes are substantially flat electrodes and are substantially unidirectionally oriented towards a direction outside of the basket. 
     SUMMARY 
     There is provided in accordance with an embodiment of the present disclosure, a catheter apparatus, including an elongated deflectable element including a distal end, a coupler connected to the distal end, a pusher including a distal portion, and being configured to be advanced and retracted through the deflectable element, a nose connector connected to the distal portion of the pusher, and including a distal receptacle having an inner surface and a distal facing opening, and an expandable assembly including a plurality of flexible polymer circuit strips, each flexible polymer circuit strip including multiple electrodes disposed thereon, the flexible polymer circuit strips being disposed circumferentially around the distal portion of the pusher, with first ends of the strips being connected to the coupler and second ends of the strips including respective hinges entering the distal facing opening and connected to the inner surface of the distal receptacle of the nose connector, the strips being configured to bow radially outward when the pusher is retracted expanding the expandable assembly from a collapsed form to an expanded form. 
     Further in accordance with an embodiment of the present disclosure the respective hinges are configured to provide a maximum angular range of movement, which is in excess of 80 degrees, between the collapsed form and the expanded form. 
     Still further in accordance with an embodiment of the present disclosure the hinges have a thickness in the range of 10 to 140 microns. 
     Additionally, in accordance with an embodiment of the present disclosure, the apparatus includes respective elongated resilient support elements connected along a given length of respective ones of the flexible polymer circuit strips providing a shape of the expandable assembly in the expanded form. 
     Moreover, in accordance with an embodiment of the present disclosure the elongated resilient support elements include Nitinol. 
     Further in accordance with an embodiment of the present disclosure the elongated resilient support elements include Polyetherimide (PEI). 
     Still further in accordance with an embodiment of the present disclosure the respective elongated resilient support elements extend along the respective strips from the coupler until before the respective hinges. 
     Additionally, in accordance with an embodiment of the present disclosure the flexible polymer circuit strips include a polyimide layer. 
     Moreover, in accordance with an embodiment of the present disclosure the hinges of the flexible polymer circuit strips are supported with a length of yarn. 
     Further in accordance with an embodiment of the present disclosure the yarn includes any one or more of the following an ultra-high-molecular-weight polyethylene yarn, or a yarn spun from a liquid-crystal polymer. 
     Still further in accordance with an embodiment of the present disclosure the flexible polymer circuit strips are covered with a thermoplastic polymer resin shrink wrap (PET). 
     Additionally, in accordance with an embodiment of the present disclosure respective ones of the second ends of respective ones of the flexible polymer circuit strips are tapered along the width of the respective ones of the flexible polymer circuit strips. 
     Moreover, in accordance with an embodiment of the present disclosure the coupler has an inner surface, the first ends of the strips being connected to the inner surface of the coupler. 
     Further in accordance with an embodiment of the present disclosure respective ones of the first ends of respective ones of the flexible polymer circuit strips include an electrical connection array. 
     Still further in accordance with an embodiment of the present disclosure, the apparatus includes a position sensor disposed in the distal receptacle of the nose connector. 
     Additionally, in accordance with an embodiment of the present disclosure, the apparatus includes a position sensor disposed between the coupler and the pusher. 
     Moreover, in accordance with an embodiment of the present disclosure, the apparatus includes a nose cap covering the distal facing opening of the nose connector. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood from the following detailed description, taken in conjunction with the drawings in which: 
         FIG. 1  is a schematic view of a basket catheter constructed and operative in accordance with an embodiment of the present invention; 
         FIGS. 2 and 3  are more detailed views of the expandable assembly of the basket catheter of  FIG. 1 ; 
         FIG. 4  is a partly exploded view of the basket catheter of  FIG. 1 ; 
         FIG. 5  is an enlarged view of a nose section of the basket catheter of  FIG. 1  with a nose cap removed; 
         FIGS. 6A and 6B  are schematic views of the expandable assembly of the basket catheter of  FIG. 1  in expanded and collapsed form; 
         FIG. 7  is a schematic view of the flexible polymer circuit strips for use in the basket catheter of  FIG. 1 ; 
         FIG. 8  is a cross-sectional view through line A-A of  FIG. 7 ; 
         FIG. 9  is a schematic view of a deflectable element of the basket catheter of  FIG. 1 ; 
         FIG. 10  is a schematic view of an irrigation sleeve of the basket catheter of  FIG. 1 ; 
         FIG. 11  is a schematic view of a pusher of the basket catheter of  FIG. 1 ; 
         FIG. 12  is a schematic view of a multi-axis position sensor of the basket catheter of  FIG. 1 ; 
         FIGS. 13A-B  are schematic views of a nose connector of the basket catheter of  FIG. 1 ; 
         FIG. 14  is a schematic view of a nose connector retainer of the basket catheter of  FIG. 1 ; 
         FIGS. 15A-B  are schematic views of a nose cap of the basket catheter of  FIG. 1 ; 
         FIG. 16  is a schematic view of a coupler of the basket catheter of  FIG. 1 ; 
         FIG. 17  is a schematic view of a single-axis position sensor of the basket catheter of  FIG. 1 ; 
         FIG. 18  is a schematic view of a proximal retainer ring of the basket container of  FIG. 1 ; and 
         FIGS. 19-20  are cross sectional views through line A-A of  FIG. 1 . 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Overview 
     Investigative electrodes on basket catheters are generally distributed along the length of the splines of the basket assembly. Proximal ends of the splines of the basket assembly are generally connected to an insertion tube of the catheter, while distal ends of the splines are connected to a pusher which is disposed within an insertion tube. The pusher may be retracted and advanced, to expand and collapse, the basket assembly, respectively. When the basket assembly is collapsed, the splines have a substantially linear formation, with the distal ends of the splines being connected to outer surface of the pusher and typically covered with a cap forming the nose of the catheter. When the basket assembly is expanded the nose of the catheter protrudes distally beyond the expanded assembly. 
     During investigative procedures, the tissue region contacted by the distal portion of the basket is of greater interest than other regions for investigative purposes, but due to the nose of the basket protruding beyond the expanded assembly, some of the distal portion surrounding the nose of the basket assembly is prevented from making contact with tissue thereby preventing using some of that distal portion for investigative purposes. 
     Basket catheters with flatter noses have been proposed, but generally these catheters suffer from various disadvantages such as the nose is not flat enough, the basket does not collapse sufficiently, and/or the structural engineering of the basket is deficient in one or more ways such that the basket fails under compression and/or tension when being deployed and/or in use. 
     Embodiments of the present invention solve the above problems by providing a catheter apparatus including an expandable basket assembly with a substantially flat nose so that electrodes may be placed close to the nose and still make contact with tissue when the basket assembly is expanded. The distal ends of the splines include hinges which are flexible enough and have a large enough angular range of bending to allow the expandable assembly to achieve its fully expanded form and its fully collapsed form, while being strong enough to withstand the various compressive and tensile stresses applied to the catheter. The distal ends of the splines are tucked into, and connected to, a receptacle at the end of the pusher so that the end of the catheter is either level with the basket assembly when the basket is expanded or only sticks out at minimal distance (for example, up to about 1 mm) from the expanded basket assembly. 
     In some embodiments, the catheter apparatus includes an elongated deflectable element, a coupler connected to the distal end of the deflectable element, and a pusher, which may be advanced and retracted through the deflectable element. 
     The apparatus also includes a nose connector connected to the distal portion of the pusher, and an expandable assembly comprising flexible polymer circuit strips. Each flexible polymer circuit strip includes multiple electrodes disposed thereon. The flexible polymer circuit strips are placed circumferentially around the distal portion of the pusher, with first ends of the strips being connected to the coupler and second ends of the strips comprising respective hinges entering a distal facing opening of a distal receptacle of the nose connector and connected to the inner surface of the distal receptacle of the nose connector. The strips are configured to bow radially outward when the pusher is retracted expanding the expandable assembly from a collapsed form to an expanded form. 
     In some embodiments, the second ends of the flexible polymer circuit strips are tapered along their width to facilitate insertion of the strips into the receptacle without overlap. In some embodiments, the first ends of the strips are connected to the inner surface of the coupler. 
     The apparatus includes respective elongated resilient support elements connected along a given length of respective ones of the flexible polymer circuit strips providing a shape of the expandable assembly in the expanded form. The respective elongated resilient support elements extend along the respective strips from the coupler until before the respective hinges thereby providing the strips with sufficient resilience where needed without adding bulk to the hinges. The elongated resilient support elements may include any suitable resilient material, for example, but not limited to, Nitinol and/or Polyetherimide (PEI). 
     The flexible polymer circuit strips may include a polyimide layer. The hinges of the flexible polymer circuit strips may be strengthened with any suitable material, for example, but not limited to, a length of yarn, which is flexible and provides tensile support to the strips. In some embodiments, a length of yarn runs the whole length of each strip including the hinges. The yarn may include any suitable yarn. For example, the yarn may include one or more of the following: an ultra-high-molecular-weight polyethylene yarn; or a yarn spun from a liquid-crystal polymer. Each flexible polymer circuit strip, its length of yarn, and elongated resilient support element may be secured together with a suitable adhesive, for example, epoxy, and then covered with a thermoplastic polymer resin shrink wrap (PET) or any other suitable covering. Windows may be created in the PET covering with a laser, mechanical removal, or any other suitable method in order to expose the electrodes. Alternatively, prior to shrinking, the PET covering may already have windows present. 
     In some embodiments, each flexible polymer circuit strip may be electrically isolated from its elongated resilient support element, for example, by coating the elongated resilient support element with an insulator or by using a covering such as a shrink wrap which wraps the elongated resilient support element and the length of yarn. In some embodiments, the elongated resilient support elements may be non-conductive. 
     The hinges (including the yarn and covering layers) may have any suitable thickness, for example, in the range of 10 to 140 microns. 
     The catheter apparatus may include one or more positions sensors, for example, a position sensor (e.g., a multi-axis sensor) disposed in the distal receptacle of the nose connector, and/or a position sensor (e.g., a single-axis sensor) disposed between the coupler and the pusher. A nose cap may be used to cover the distal facing opening of the nose connector. 
     SYSTEM DESCRIPTION 
     Reference is now made to  FIG. 1 , which is a schematic view of a basket catheter  10  constructed and operative in accordance with an embodiment of the present invention. The basket catheter  10  includes an elongated deflectable element  12  having a distal end  14 , a coupler  16  connected to the distal end  14 , and a pusher  18  including a distal portion  20 . The pusher  18  is configured to be advanced and retracted through the deflectable element  12 , for example, using a manipulator or handle (not shown). The basket catheter  10  also includes an expandable assembly  22  comprising a plurality of flexible polymer circuit strips  24  (only some labeled for the sake of simplicity). Each flexible polymer circuit strip  24  includes multiple electrodes  26  disposed thereon (only some labeled for the sake of simplicity). The formation of the various elements and how they are connected with each other are described in more detail with reference to the  FIGS. 4-20 . 
     Reference is now made to  FIGS. 2 and 3 , which are more detailed views of the expandable assembly  22  of the basket catheter  10  of  FIG. 1 .  FIGS. 2 and 3  show the electrodes  26  on the flexible polymer circuit strips  24  more clearly. 
       FIG. 2  shows that the electrodes  26  are not disposed on the proximal portions of the flexible polymer circuit strips  24 . The basket catheter  10  includes a nose connector  30  connected to the distal portion  20  of the pusher  18 . The flexible polymer circuit strips  24  are connected via hinges  28  (only some labeled for the sake of simplicity) of the flexible polymer circuit strips  24  to the nose connector  30 . 
     Reference is now made to  FIGS. 4-5 .  FIG. 4  is a partly exploded view of the basket catheter  10  of  FIG. 1 .  FIG. 5  is an enlarged view of a nose section of the basket catheter  10  of  FIG. 1  with a nose cap  32  removed. 
       FIG. 4  shows the nose cap  32  and the coupler  16  removed from the basket catheter  10  to illustrate how the flexible polymer circuit strips  24  are connected to the nose connector  30  and the coupler  16 . The nose connector  30  is connected to the distal portion  20  of the pusher  18 . The proximal end of the coupler  16  may be connected to the elongated deflectable element  12  using any suitable connection method, such as using adhesive, for example, epoxy. The nose connector  30  is secured to the distal portion  20  of the pusher  18  using a center electrode ring  40 , which is described in more detail with reference to  FIGS. 14 and 19 . The flexible polymer circuit strips  24  are disposed circumferentially around the distal portion  20  of the pusher  18 , with first ends  42  (only some labeled for the sake of simplicity) of the strips  24  being connected to an inner surface  44  of the coupler  16 . The connection between the flexible polymer circuit strips  24  and the inner surface  44  is shown more clearly with reference to  FIG. 20 . 
       FIG. 5  shows that the nose connector  30  includes a distal receptacle  34  having an inner surface  36  and a distal facing opening  38 . The nose connector  30  is described in more detail with reference to  FIGS. 13A-B  and  19 .  FIG. 5  shows that second ends  46  ( FIG. 5 ) (only some labeled for the sake of simplicity) of the strips  24  comprising the respective hinges  28  ( FIG. 5 ) entering the distal facing opening  38  ( FIG. 5 ) and are connected to the inner surface  36  ( FIG. 5 ) of the distal receptacle  34  ( FIG. 5 ) of the nose connector  30 . 
       FIG. 4  shows that the basket catheter  10  also includes respective elongated resilient support elements  48  connected along a given length of respective ones of the flexible polymer circuit strips  24  providing a shape of the expandable assembly  22  in the expanded form of the expandable assembly  22 . The elongated resilient support elements  48  may include any suitable material, for example, but not limited to, Nitinol and/or Polyetherimide (PEI). 
       FIG. 4  shows that the respective elongated resilient support elements  48  extend along inner surface of the respective strips  24  from the coupler  16 , while  FIG. 5  shows that the elongated resilient support elements  48  extend along the respective flexible polymer circuit strips  24  until before the respective hinges  28 . Insets  50  of  FIG. 5  show one of the hinges  28  and a portion of one of the flexible polymer circuit strips  24  adjacent to that hinge  28 . The insets  50  illustrate that the elongated resilient support element  48  does not extend to the region of the hinge  28 . It can also be seen that the hinge region is much thinner than the region including the elongated resilient support element  48 . The hinges  28  may have any suitable thickness, for example, in the range of approximately 10 to approximately 140 microns. The strip  24  are folded such that strip  24  defines a generally perpendicular configuration (inset  50 ) to each other. 
     In some embodiments, each of the flexible polymer circuit strips  24  comprises a polyimide layer. The flexible polymer circuit strips  24  may be composed of any suitable materials. The flexible polymer circuit strips  24  are described in more detail with reference to  FIGS. 7 and 8 . 
       FIG. 5  also shows that respective ones of the second ends  46  of respective ones of the flexible polymer circuit strips  24  are tapered along the width of the respective ones of the flexible polymer circuit strips  24  to allow inserting the second ends  46  into the distal receptacle  34  without overlap. The hinges  28  may be connected to the inner surface  36  of the distal receptacle  34  using any suitable adhesive, for example, epoxy, and/or using any suitable connection method. 
     The hinges  28  of the flexible polymer circuit strips  24  are supported with a length of yarn  52 , which typically runs the length of each respective flexible polymer circuit strip  24 . Each flexible polymer circuit strip  24  along with the yarn  52  and the associated elongated resilient support element  48  may be covered with a suitable covering  54 , e.g., thermoplastic polymer resin shrink wrap (PET) described in more detail with reference to  FIG. 8 . Yarn  52  can be any suitable high strength polymer including, for example, ultra high molecular weight polyethylene (Spectra or Dyneema), Kevlar, liquid crystal polymer (Vectran) and the like. 
     Reference is now made to  FIGS. 6A and 6B , which are schematic views of the expandable assembly  22  of the basket catheter  10  of  FIG. 1  in expanded and collapsed form, respectively. The flexible polymer circuit strips  24  are configured to bow radially outward when the pusher  18  is retracted expanding the expandable assembly  22  from a collapsed form to an expanded form. The collapsed form of the expandable assembly  22  represents the non-stressed form of the flexible polymer circuit strips  24  which are provided with their shape using the elongated resilient support elements  48  ( FIG. 4 ). 
     In some embodiments, the flexible polymer circuit strips  24  are formed as flat strips as described in more detail with reference to  FIG. 7 . The distal ends of the flexible polymer circuit strips  24  are connected to the inner surface  36  ( FIG. 5 ) of the nose connector  30 . At that point the flat flexible polymer circuit strips  24  are generally parallel with a line  58 , which is an extension of an axis of the nose connector  30  extended distally beyond the distal end of the nose connector  30 . The proximal ends of the flexible polymer circuit strips  24  are then connected to the coupler  16  so that in the collapsed form, the angle between a tangent  56  to the flexible polymer circuit strips  24  and the line  58  is close to 180 degrees, while in the expanded form, the angle between the tangent  56  and the line  58  is about 90 degrees. Therefore, in operation (when the flexible polymer circuit strips  24  are connected to the nose connector  30  and the coupler  16 ) the hinges  28  are configured to provide a maximum angular range of movement of the flexible polymer circuit strips  24  of about 90 degrees and generally in excess of 80 degrees. However, the hinges  28  are capable of bending 180 degrees or more. The maximum angular range is defined as the maximum angular range between the tangent  56  to the flexible polymer circuit strips  24  and the line  58 . The tangent  56  to the most distal portion of the flexible polymer circuit strips  24  generally provides the maximum angular range between the flexible polymer circuit strips  24  and the line  58 . 
     Reference is now made to  FIG. 7 , which is a schematic view of the flexible polymer circuit strips  24  for use in the basket catheter  10  of  FIG. 1 . The flexible polymer circuit strips  24  may be formed from a single piece of polymer, such as polyimide. Circuit strips  24  may be connected to each other by polyimide, or assembled as individual pieces that are held in proper alignment and secured to coupler  16 . By manufacturing circuit strips  24  as individual components the yield of the base circuit may be increased as a failed electrode scraps one circuit strip rather than an entire assembly of strips. Respective first ends  42  of the respective flexible polymer circuit strips  24  include an electrical connection array  60 . An inset  62  shows that the electrical connection array  60  includes electrical contacts  64  thereon (only some labeled for the sake of simplicity). The electrical contacts  64  are connected via traces (not shown) on the back of the flexible polymer circuit strips  24  to respective ones of the electrodes  26  disposed on the front of the flexible polymer circuit strips  24 . Away from the region of the first ends  42 , the flexible polymer circuit strips  24  are separate from each other to allow the flexible polymer circuit strips  24  to form the expandable assembly  22  ( FIG. 1 ) when connected to the basket catheter  10 . Wires (not shown) may connect the electrodes  26  to control circuitry (not shown) via the electrical contacts  64 . The wires may be disposed in lumens  66  ( FIG. 4 ) of the elongated deflectable element  12  ( FIG. 4 ). 
     The flexible polymer circuit strips  24  may have any suitable dimensions. For example, the length of the flexible polymer circuit strips  24  may be in the range of 10 mm to 60 mm, e.g., 30 mm the width of the flexible polymer circuit strips  24  may be in the range of 0.25 mm to 3 mm, e.g., 0.72 mm, the thickness of the flexible polymer circuit strips  24  may be in the range of 0.005 mm to 0.14 mm. 
     Reference is now made to  FIG. 8 , which is a cross-sectional view through line A-A of  FIG. 7 . The yarn  52  is run along the length of the elongated resilient support element  48 , e.g., formed from Nitinol or PEI, and beyond so that the yarn  52  will also run the length of the hinge  28  comprised of the flexible polymer circuit strips  24 . The elongated resilient support elements  48  may have any suitable thickness, for example, in the range of 0.025 mm to 0.25 mm. A covering  68 , such as a thermoplastic polymer resin shrink wrap (PET), is placed over the yarn  52  and the elongated resilient support element  48 . Epoxy is injected into the covering  68 . Heat is then applied to the covering thereby shrinking the covering over the yarn  52  and the elongated resilient support element  48 . One reason to cover the elongated resilient support element  48  with the covering  68  is to electrically isolate the elongated resilient support element  48  from the circuit traces of the flexible polymer circuit strip  24 . The covering  68  may be omitted, for example, if the elongated resilient support element  48  is covered with an insulating coating (e.g., polyurethane) or is comprised of an insulating material. 
     The flexible polymer circuit strip  24  are then placed over the yarn  52  and the elongated resilient support element  48  with the circuit trace side of the flexible polymer circuit strip  24  facing the elongated resilient support element  48  and the electrodes  26  of the flexible polymer circuit strips  24  facing away from the elongated resilient support element  48 . The covering  54  is disposed around the flexible polymer circuit strip  24 , yarn  52 , and elongated resilient support element  48  combination, and epoxy  70  is injected into the covering  54 . The covering  54  is then heated thereby shrinking the covering  54  around the combination. The flexible polymer circuit strips  24  are therefore covered with the covering  54 , e.g., a thermoplastic polymer resin shrink wrap (PET). 
     The yarn  52  may comprises any one or more of the following: an ultra-high-molecular-weight polyethylene yarn; or a yarn spun from a liquid-crystal polymer. The yarn  52  may be any suitable linear density, for example, in a range between  25  denier and  250  denier. 
     Reference is now made to  FIG. 9 , which is a schematic view of the elongated deflectable element  12  of the basket catheter  10  of  FIG. 1 . The elongated deflectable element  12  may be produced from any suitable material, for example, polyurethane or polyether block amide. The distal end  14  of the elongated deflectable element  12  has a smaller outer diameter than the rest of the elongated deflectable element  12  to accept the coupler  16  thereon as shown in  FIG. 20 . The elongated deflectable element  12  includes lumens  66  for inserting various tubes and wires therein as described herein. The elongated deflectable element  12  may have any suitable outer diameter and length, for example, the outer diameter may be in a range between 1 mm and 4 mm and the length may be in a range between 1 cm and 15 cm. 
     Reference is now made to  FIG. 10 , which is a schematic view of an irrigation sleeve  72  of the basket catheter  10  of  FIG. 1 . The irrigation sleeve  72  is a flexible tube which is disposed in one of the lumens  66  ( FIG. 9 ) of the elongated deflectable element  12  ( FIG. 9 ). The irrigation sleeve  72  may be used to carry irrigation fluid to the region of the expandable assembly  22  ( FIG. 1 ). The irrigation sleeve  72  is sized to fit in one of the lumens  66  (typically a central lumen) of the elongated deflectable element  12  and extend beyond the distal end  14  ( FIG. 9 ) of the elongated deflectable element  12  as shown in  FIG. 20 . The inner and outer diameter of the irrigation sleeve  72  may be in the range between 3 mm and 5 mm. The irrigation sleeve  72  may be formed from any suitable material, for example, but not limited to polyimide, polyurethane, polyether block amide, or polyethylene terephthalate. 
     Reference is now made to  FIG. 11 , which is a schematic view of the pusher  18  of the basket catheter  10  of  FIG. 1 . The pusher  18  is a flexible tube and is disposed in the irrigation sleeve  72 . The pusher  18  is sized to slide in the irrigation sleeve  72  and allow room for irrigation fluid to pass between the irrigation sleeve  72  and the pusher  18 . The inner diameter of the pusher  18  is sized to accommodate wiring of a multi-axis position sensor described with reference to  FIG. 12 . The pusher  18  extends beyond the distal end  14  of the elongated deflectable element  12  ( FIG. 9 ) until the nose connector  30  as shown in  FIG. 19 . The pusher  18  may be formed from any suitable material, for example, but not limited to polyimide with or without braiding, polyether ether ketone (PEEK) with or without braiding, or polyamide with or without braiding. 
     Reference is now made to  FIG. 12 , which is a schematic view of a multi-axis position sensor  74  of the basket catheter  10  of  FIG. 1 . The multi-axis position sensor  74  may comprise a dual-axis or triple-axis position sensor, for example, a magnetic position sensor comprising multiple orthogonal coils. Wiring  76  is used to connect the multi-axis position sensor  74  via the hollow of the pusher  18  ( FIG. 11 ) to a position computation system (not shown) disposed proximally to the basket catheter  10 . The multi-axis position sensor  74  and the wiring  76  are shown in more detail in  FIGS. 5 and 19 . 
     Reference is now made to  FIGS. 13A-B , which are schematic views of the nose connector  30  of the basket catheter  10  of  FIG. 1 . The nose connector  30  may be formed from any suitable material, for example, but not limited to polycarbonate with or without glass filler, PEEK with or without glass filler, or PEI with or without glass filler. The nose connector  30  includes a proximal cavity  78  ( FIG. 13A ) in which the pusher  18  ( FIG. 11 ) is secured and through which the wiring  76  passes as shown in  FIG. 19 .  FIG. 13B  also shows the distal receptacle  34 , the inner surface  36 , and the distal facing opening  38 . The distal receptacle  34  houses the multi-axis position sensor  74  ( FIG. 12 ) and the hinges  28  ( FIG. 5 ) which are connected to the inner surface  36 . 
     Reference is now made to  FIG. 14 , which is a schematic view of the center electrode ring  40  of the basket catheter  10  of  FIG. 1 . Electrode  40  is electrically connected to a wire (not shown) that passes through the slot in the side of proximal cavity  78  and into pusher  18 . The center electrode ring  40  may be formed from any suitable material, for example, but not limited to noble metals and their alloys comprising platinum, palladium, gold, or iridium. The center electrode ring  40  serves a secondary role by providing mechanical support around the proximal cavity  78  ( FIG. 13A ) of the nose connector  30  to secure the nose connector  30  to the pusher  18  ( FIG. 11 ) as shown in  FIG. 19 . 
     Reference is now made to  FIGS. 15A-B , which are schematic views of the nose cap  32  of the basket catheter  10  of  FIG. 1 . The nose cap  32  includes a hollow cylinder  80  covered with a cover  82  which may be wider than the hollow cylinder  80 . The nose cap  32  may be formed from any suitable material, for example, but not limited to polycarbonate with or without glass filler, PEEK with or without glass filler, or PEI with or without glass filler. The nose cap  32  is sized to fit in the distal receptacle  34  ( FIG. 13B ) of the nose connector  30  ( FIG. 13B ) and cover the distal facing opening  38  ( FIG. 13B ) while allowing space for the multi-axis position sensor  74  ( FIG. 12 ) and the hinges  28  ( FIG. 5 ) therein as shown in  FIG. 19 . The nose cap  32  may optionally be sized to provide a pressure fit against the hinges  28  to prevent the hinges  28  from being pulled away from the inner surface  36  ( FIG. 13B ) of the nose connector  30  ( FIG. 13B ). The nose connector  30  may also function to protect the multi-axis position sensor  74 . 
     Reference is now made to  FIG. 16 , which is a schematic view of the coupler  16  of the basket catheter  10  of  FIG. 1 . The coupler  16  typically comprises a hollow tube and may be formed from any suitable material, for example, but not limited to polycarbonate with or without glass filler, PEEK with or without glass filler, polyimide, polyamide, or PEI with or without glass filler. The coupler  16  may be sized to have the same inner diameter as the outer diameter of the distal end  14  ( FIG. 9 ) of the elongated deflectable element  12  ( FIG. 9 ) and the same outer diameter as the proximal portion of the elongated deflectable element  12 . The coupler  16  is also sized to surround various elements described in more detail with reference to  FIG. 20 . 
     Reference is now made to  FIG. 17 , which is a schematic view of a single-axis position sensor  86  of the basket catheter  10  of  FIG. 1 . The single-axis position sensor  86  may include any suitable position sensor, for example, a magnetic position sensor comprising a coil wound on a hollow cylinder  88 . Wiring (not shown) from the single-axis position sensor  86  may be passed down one of the lumens  66  ( FIG. 9 ) to a position computation system (not shown) disposed proximally to the basket catheter  10 . The hollow cylinder  88  is sized to accommodate the irrigation sleeve  72  therein as shown in  FIG. 20 . The outer diameter and length of the single-axis position sensor  86  is sized to fit in the coupler  16  ( FIG. 16 ). The hollow cylinder  88  may be formed from any suitable material, for example, but not limited to, a material used as a magnetic core. 
     Reference is now made to  FIG. 18 , which is a schematic view of a proximal retainer ring  84  of the basket container  10  of  FIG. 1 . The proximal retainer ring  84  is configured to provide a pressure fit around the distal end of the irrigation sleeve  72  ( FIG. 10 ) and retain the single-axis position sensor  86  ( FIG. 17 ) to be adjacent to the distal end  14  ( FIG. 9 ) of the elongated deflectable element  12  ( FIG. 9 ) as shown in  FIG. 20 . The proximal retainer ring  84  also serves to secure the flexible polymer circuits  24  between the retainer ring  84  and the coupler  16 . The proximal retainer ring  84  may be formed from any suitable material, for example, but not limited to polycarbonate with or without glass filler, PEEK with or without glass filler, or PEI with or without glass filler. 
     Reference is now made to  FIGS. 19-20 , which are cross sectional views through line A-A of  FIG. 1 .  FIG. 19  shows a distal portion of the expandable assembly  22 , while  FIG. 20  shows a proximal portion. 
       FIG. 19  shows that the distal portion  20  of the pusher  18  is disposed in the proximal cavity  78  of the nose connector  30  and is secured therein using the center electrode ring  40  disposed around the outside of the proximal cavity  78 . The multi-axis position sensor  74  is disposed in the distal receptacle  34  of the nose connector  30  with the wiring  76  extending proximally through the pusher  18 . The second ends  46  of the flexible polymer circuit strips  24  are connected to the inner surface  36  of the distal receptacle  34  of the nose connector  30 . The elongated resilient support elements  48  extend along the length of the flexible polymer circuit strips  24  until, but not including, the hinges  28 . The nose cap  32  is inserted into the distal receptacle  34  with the hollow cylinder  80  surrounding the distal portion of the multi-axis position sensor  74  and providing pressure against the second ends  46  of the flexible polymer circuit strips  24 . The nose cap  32  covers the distal facing opening  38  of the nose connector  30 . 
       FIG. 20  shows that the irrigation sleeve  72  is disposed in the elongated deflectable element  12 . The pusher  18  is disposed in the irrigation sleeve  72 . The wiring  76  is disposed in the pusher  18 . The single-axis position sensor  86  is disposed around the irrigation sleeve  72  (between the coupler  16  and the pusher  18 ) close to the distal end  14  of the elongated deflectable element  12 . The proximal retainer ring  84  provides a pressure fit around the irrigation sleeve  72  and keeps the single-axis position sensor  86  in place distally to the distal end  14  of the elongated deflectable element  12 . The proximal end of the coupler  16  is connected to the distal end  14  of the elongated deflectable element  12 . The first ends  42  of the flexible polymer circuit strips  24  are connected to the inner surface  44  of the coupler  16 .  FIG. 20  shows that the elongated resilient support elements  48  extend along the respective strips  24  from the coupler  16  until before the respective hinges  28  ( FIG. 19 ). 
     While the expandable assembly is shown without being mounted to a flexible membrane, it is within the scope of the invention that the expandable assembly can be provided with a membrane (e.g., balloon like surface) as a base substrate for the circuit strips. As well, the membrane can be used as a covering layer over the circuit strips  24  with electrodes  26  being exposed (or not covered by the membrane for exposure) to the ambient environment (e.g., inside organ tissues). 
     As used herein, the terms “about” or “approximately” for any numerical values or ranges indicate a suitable dimensional tolerance that allows the part or collection of components to function for its intended purpose as described herein. More specifically, “about” or “approximately” may refer to the range of values ±20% of the recited value, e.g. “about 90%” may refer to the range of values from 72% to 108%. 
     Various features of the invention which are, for clarity, described in the contexts of separate embodiments may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable sub-combination. 
     The embodiments described above are cited by way of example, and the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the invention includes both combinations and sub-combinations of the various features described hereinabove, as well as variations and modifications thereof which would occur to persons skilled in the art upon reading the foregoing description and which are not disclosed in the prior art.