ELECTRODE DESIGNS FOR CATHETERS

Abstract

The disclosed technology includes a catheter comprising an elongated deflectable element extending along a longitudinal axis from a proximal end to a distal end, a position electrode attached to the elongated deflectable element proximate the distal end and configured for impedance-based position tracking, and a covering at least partially enclosing the position electrode. The covering can comprise a plurality of apertures such that a portion of a conductive surface of the position electrode is exposed through each aperture of the plurality of apertures.

Claims

1. A catheter comprising: an elongated deflectable element extending along a longitudinal axis from a proximal end to a distal end; a position electrode attached to the elongated deflectable element proximate the distal end and configured for impedance-based position tracking; and a covering at least partially enclosing the position electrode, the covering comprising a plurality of apertures such that a portion of a conductive surface of the position electrode is exposed through each aperture of the plurality of apertures.

2. The catheter according to claim 1 further comprising a magnetic position sensor attached to the elongated deflectable element proximate the distal end.

3. The catheter according to claim 2, the magnetic position sensor disposed at least partially around an outer perimeter of the position electrode.

4. The catheter according to claim 1, the covering comprising a non-conductive polymer material and the conductive surface of the position electrode being disposed a distance below an outer surface of the covering such that the conductive surface and the outer surface are non-planar.

5. The catheter according to claim 1, further comprising a conductive polymer coating disposed in each aperture of the plurality of apertures.

6. The catheter according to claim 1, the plurality of apertures comprising a plurality of circular apertures.

7. The catheter according to claim 1, the plurality of apertures comprising a plurality of polygonal apertures.

8. The catheter according to claim 1 further comprising an end effector disposed at the distal end of the elongated deflectable element, wherein the position electrode comprises a first position electrode disposed at a proximate end of the end effector, the catheter further comprising: a second position electrode disposed at a distal end of the end effector.

9. The catheter according to claim 8 further comprising a first magnetic position sensor disposed at the proximal end of the end effector; and a second magnetic position sensor disposed at the distal end of the end effector.

10. The catheter according to claim 1, the plurality of apertures comprising a plurality of elongated slits, each elongated slit of the plurality of elongated slits extending from near a first end of the position electrode to near a second end of the position electrode.

11. The catheter according to claim 1, the covering comprising a conductive polymer material.

12. A medical system comprising: a handle; and a probe attached to the handle comprising: an elongated deflectable element extending along a longitudinal axis from a proximal end to a distal end; a position electrode attached to the elongated deflectable element proximate the distal end and configured for impedance-based position tracking; and a covering at least partially enclosing the position electrode, the covering comprising a conductive polymer; and a plurality of external electrodes, the plurality of external electrodes configured to receive a current output by the position electrode.

13. The medical system according to claim 12, the covering further comprising a plurality of apertures such that a portion of a conductive surface of the position electrode is exposed through each aperture of the plurality of apertures.

14. The medical system according to claim 13, the conductive surface of the position electrode being disposed a distance below an outer surface of the covering such that the conductive surface and the outer surface are non-planar.

15. The medical system according to claim 12, the probe further comprising a magnetic position sensor attached to the elongated deflectable element proximate the distal end.

16. The medical system according to claim 15, the magnetic position sensor disposed at least partially underneath the position electrode.

17. The medical system according to claim 15 further comprising a magnetic field generator configured to generate a magnetic field, the magnetic position sensor configured to output a signal based at least in part on the magnetic field.

18. The medical system according to claim 17, the signal being a first signal and the medical system further comprising a controller configured to: receive the first signal from the magnetic position sensor; receive a second signal from the plurality of external electrodes; and determine, based at least in part on the first signal or the second signal, a position of the probe.

19. The medical system according to claim 18, the controller being further configured to determine, based at least in part on the first signal or the second signal, an orientation of the probe.

20. The medical system according to claim 12, the handle and the probe comprising a lumen extending therethrough configured to permit a catheter device to be inserted therethrough.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] The present invention will be understood from the following detailed description, taken in conjunction with the drawings in which:

[0066] FIG. 1 is a schematic view of a basket catheter constructed and operative in accordance with an embodiment of the present invention;

[0067] FIGS. 2 and 3 are more detailed views of the expandable assembly of the basket catheter of FIG. 1;

[0068] FIG. 4 is a partly exploded view of the basket catheter of FIG. 1;

[0069] FIG. 5 is an enlarged view of a nose section of the basket catheter of FIG. 1 with a nose cap removed;

[0070] FIGS. 6A and 6B are schematic views of the expandable assembly of the basket catheter of FIG. 1 in expanded and collapsed form;

[0071] FIG. 7 is a schematic view of the flexible polymer circuit strips for use in the basket catheter of FIG. 1;

[0072] FIG. 8A is a cross-sectional view through line A-A of FIG. 7;

[0073] FIGS. 8B-8I illustrate example apertures formed in a covering of the flexible polymer circuit strips of FIG. 7;

[0074] FIG. 8J is a table illustrating impedance values for example aperture patterns formed in the covering of the flexible polymer circuit strips of FIG. 7;

[0075] FIG. 9 is a schematic view of a deflectable element of the basket catheter of FIG. 1;

[0076] FIG. 10 is a schematic view of an irrigation sleeve of the basket catheter of FIG. 1;

[0077] FIG. 11 is a schematic view of a pusher of the basket catheter of FIG. 1;

[0078] FIG. 12 is a schematic view of a multi-axis position sensor of the basket catheter of FIG. 1;

[0079] FIGS. 13A-B are schematic views of a nose connector of the basket catheter of FIG. 1;

[0080] FIG. 14 is a schematic view of a nose connector retainer of the basket catheter of FIG. 1;

[0081] FIGS. 15A-B are schematic views of a nose cap of the basket catheter of FIG. 1;

[0082] FIG. 16 is a schematic view of a coupler of the basket catheter of FIG. 1;

[0083] FIG. 17 is a schematic view of a single-axis position sensor of the basket catheter of FIG. 1;

[0084] FIG. 18 is a schematic view of a proximal retainer ring of the basket container of FIG. 1;

[0085] FIGS. 19-20 are cross sectional views through line A-A of FIG. 1;

[0086] FIG. 21 illustrates a flowchart of a method of forming a flexible polymer circuit strip of the basket catheter of FIG. 1 in accordance with an embodiment of the present invention; and

[0087] FIG. 22 illustrates another catheter comprising position sensors, in according with an embodiment of the present invention.

DESCRIPTION OF EXAMPLE EMBODIMENTS

OVERVIEW

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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).

[0095] 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 (or apertures) 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.

[0096] The flexible polymer circuit strips may further include a conductive polymer coating, such as poly(3,4-ethylenedioxythiophen) (PEDOT) or poly(3, 4 ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), over each electrode to help protect the electrode, reduce input impedance, and enhance the signal-to-noise ratio. The conductive polymer coating may be applied to each electrode by dipping the electrode in a solution comprising the conductive polymer coating and then passing an electrical current through the electrode. As the current passes through each electrode, the conductive polymer coating adheres to the surface of the electrode.

[0097] To help reduce the likelihood that the conductive polymer coating is damaged by rubbing on the sheath or contacting other objects, the disclosed technology can include forming apertures in the PET covering with a laser, mechanical removal, or any other suitable method in order to expose only a portion of each electrode. In other words, rather than removing the PET covering to expose the entire surface of the electrode, the disclosed technology can include removing smaller portions of the PET covering to form small apertures through the PET covering to expose only portions of the electrode’s surface. By including small apertures through the PET, the PET can provide protection to the conductive polymer coating which is positioned in each aperture by preventing the conductive polymer coating from contacting the sheath or other objects. The apertures can be sized, shaped, and positioned to help reduce the likelihood that the conductive polymer coating will contact the sheath or other objects while also ensuring the electrode is capable of detecting electrical signals of the heart. Reduction in damage to the conductive polymer coating may result in more accurate signals from the electrodes and/or less risk of a health threat due to shedding of coating into the patient’s heart and/or vasculature.

[0098] 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.

[0099] The hinges (including the yarn and covering layers) may have any suitable thickness, for example, in the range of 10 to 140 microns.

[0100] 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.

[0101] The disclosed technology can further include a catheter configured for delivery of other catheter devices into a body of a patient. In other words, the disclosed technology can include a catheter sheath configured to guide other catheter devices into an organ in the body. For example, the catheter can include a handle and an elongated deflectable element that each comprise a lumen extending therethrough. A physician can use the catheter to navigate to a location of interest in an organ (e.g., a heart) and to position a distal end of the catheter near the area of interest. The physician can then insert a second catheter (e.g., a basket catheter for mapping and/or ablation) through the lumen to deliver the second catheter to the location of interest near the distal end of the catheter.

[0102] The catheter can include position sensors configured for determining a position and orientation of the catheter. The catheter, for example, can include electrodes configured for impedance-based tracking as well as magnetic position sensors configured for magnetic-based position tracking. Details of a catheter having electrodes configured for impedance-based tracking as well as magnetic position sensing are disclosed in U.S. Pat. App. No. 17/547,517 filed on Dec. 10, 2021, the entirety of which is incorporated herein by reference as if fully set forth herein and is included in the Appendix attached hereto. The electrodes and magnetic position sensors can be covered with a polymer covering and apertures can be formed therethrough in accordance with other examples described herein. The apertures can further include a conductive polymer coating to help protect the electrode, reduce input impedance, and enhance the signal-to-noise ratio. In other examples, the electrodes can have a conductive polymer covering placed over the electrodes without having any apertures which can help to protect the electrode and reduce input impedance and enhance the signal-to-noise ratio as compared to non-conductive polymer.

[0103] Further advantages of the disclosed technology will become apparent throughout the following description and with reference to the drawings.

SYSTEM DESCRIPTION

[0104] 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. 4-21.

[0105] 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.

[0106] 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.

[0107] 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.

[0108] 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.

[0109] 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).

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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. 8A. 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.

[0114] 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).

[0115] 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.

[0116] 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).

[0117] 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.

[0118] Reference is now made to FIG. 8A, 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.

[0119] The yarn 52 may comprise 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.

[0120] 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).

[0121] As illustrated in FIG. 8A, apertures 55 can be formed through the covering 54 to expose the electrode 26. In some examples, the apertures 55 can expose the entire outer surface of each electrode 26 or the apertures can expose only a portion of the outer surface of each electrode 26. The apertures 55 can be formed by using a laser to cut, or otherwise remove, the covering 54 to expose the electrode 26. In other examples, the apertures 55 can be formed by mechanically removing the covering 54, by chemically etching the covering, plasma etching the covering, or by other suitable methods of removing the covering 54 to form the apertures 55. The covering 54 can be removed such that the conductive surface of each electrode 26 is disposed approximately 12 microns below an outer surface of the covering 54. As will be described in greater detail in relation to FIGS. 8B-8I, if the apertures 55 expose only a portion of the outer surface of each electrode 26, the apertures 55 can comprise several small apertures 55 which collectively define a conductive area that is less than 50% of the conductive surface of the electrode 26.

[0122] Some or all of the electrodes 26 can also be coated with a coating 27 to help ensure the electrode 26 is able to properly detect electrical signals of the heart. The coating 27 can be any type of coating suitable for the application. As a non-limiting example, the coating 27 can be poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3, 4 ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), electrochemically grown iridium oxide, electrochemically grown Titanium Nitride (TiN) or any other suitable coating for the particular application. The coating 27 can help to reduce the overall impedance of the electrode 26. In some examples, the coating 27 can be applied to the exposed surface of the electrode 26 such that the overall impedance can be reduced by about 99% at low frequencies. As an example, the coating 27 can be configured such that the input impedance to each electrode 26 is measured at less than 13,000 ohms at 1 Hz.

[0123] The coating 27 can be a hydrogel that can be electrochemically grown or adhered to the electrode 26 when a current is passed through the electrode 26. In other examples, the coating 27 can be mechanically applied to each electrode 26 by spraying, painting, dipping, or otherwise covering the electrode 26 with the coating 27. The coating can have a thickness between 10 nanometers and 10 microns. In some examples, the coating can be a thickness that is less than the thickness of the covering 54 such that the covering 54 can help to protect the coating 27 from contacting the coupler 16, the deflectable element 12, or other objects which can damage the coating 27.

[0124] Reference is now made to FIGS. 8B-8I, which illustrate example apertures 55 formed in a covering of the flexible polymer circuit strips of FIG. 7. By forming apertures 55 formed through the covering 54 to expose a surface of the electrode 26, the exposed surface of the electrode 26 can be coated with the coating 27. As illustrated in FIGS. 8B-8I, the apertures 55 can be many shapes, sizes, and configurations. As will be appreciated by one of ordinary skill in the art, by changing the shape, size, and configuration of the apertures 55, the amount of exposed surface area of the electrodes 26 can be either increased or decreased, effectively increasing or decreasing the conductive surface area of the electrode 26. Furthermore, by increasing or decreasing the exposed surface area of the electrodes 26, the amount of coating 27 that can be applied to an aperture 55 will also be increased or decreased. In other words, as the apertures 55 increase in size, the surface area of the coating 27 in each aperture 55 will also increase which can cause the coating 27 to be more likely to rub on objects and become delaminated. Thus, as the aperture 55 size decreases, the covering 54 can provide more mechanical protection to the coating 27 to help reduce the likelihood of the coating 27 coming into contact with objects as the basket catheter 10 is used. As will be appreciated, however, as the size of a given aperture 55 is reduced, the conductive surface area of the electrode 26 will also be reduced. Therefore, the size, shape, and configuration of the apertures 55 over an electrode 26 can be optimized to allow for the electrode to sufficiently detect electrical signals while also ensuring the covering 54 provides sufficient mechanical protection to the coating 27. Manufacturability is another consideration. Presently, it is preferred that features of the covering 54 are at least 0.003 inches (76 microns) to avoid damaging the covering 54 between apertures 55 during manufacturing.

[0125] FIG. 8B illustrates an example electrode 26 of a flexible polymer circuit strip 24 having circular apertures 55A through the covering 54. In this example, eight circular apertures 55A can be formed through the covering 54 with each circular aperture 55A being spaced equally from each other. As will be appreciated, more or fewer circular aperture 55A can be formed through the covering 54 depending on the application. Furthermore, in some examples, the circular apertures 55A can be unequally spaced from each other. The coating 27 can be adhered to the exposed surface of the electrode 26 within each circular aperture 55A.

[0126] In other examples, the apertures 55 can comprise a polygonal shape. For example, FIG. 8C illustrates an electrode 26 of a flexible polymer circuit strip 24 having rectangular apertures 55B through the covering 54. In this example, fifteen rectangular apertures 55B can be formed through the covering 54 with each rectangular aperture 55B being spaced equally from each other. The rectangular apertures 55B can comprise a square or other rectangular shape. As another example, FIG. 8D illustrates an electrode 26 of a flexible polymer circuit strip 24 having decagonal apertures 55C through the covering 54. In this example, fifteen decagonal apertures 55C can be formed through the covering 54 with each decagonal aperture 55C being spaced equally from each other. As yet another example, FIG. 8E illustrates an electrode 26 of a flexible polymer circuit strip 24 having triangular apertures 55D through the covering 54. In this example, nineteen triangular apertures 55D can be formed through the covering 54. The triangular apertures 55D can be offset between each row of triangular apertures 55D such that a first row comprises four triangular apertures 55D while a second row comprises three triangular apertures 55D. Further, alternating rows can be inverted in relation to the one previous. This can allow for partially nesting of the tip of the inverted triangular aperture 55D between two other triangular apertures 55D in the previous row. The coating 27 can be adhered to the exposed surface of the electrode 26 within each rectangular aperture 55B, decagonal aperture 55C, triangular aperture 55D, etc.

[0127] As will be appreciated by one of skill in the art, apertures 55 of various other shapes and sizes can be formed through the covering 54 to expose the surface of the electrode 26. Furthermore, apertures 55 of various shapes can be formed through the covering 54 over a single electrode 26. For example, circular apertures 55A, decagonal apertures 55C, and triangular apertures 55D can be formed together over a single electrode 26. Similarly, apertures 55 of one size can be formed through the covering 54 over an electrode 26 along with apertures 55 of a different size. Further still, the apertures 55 may be equally spaced across the surface of the electrode 26 or unequally spaced across the surface of the electrode 26.

[0128] FIGS. 8F and 8G illustrate example electrodes 26 of a flexible polymer circuit strip 24 having apertures 55 which are elongated slits 55E, 55F formed through the covering 54. At least four elongated slits 55E, 55F can be formed through the covering 54 to expose the surface of the electrode 26, although it will be appreciated that more or fewer elongated slits 55E, 55F can be formed depending on the application. In the example illustrated in FIG. 8F, the elongated slits 55E can extend from near one end of the electrode 26 to near a second end of the electrode 26 in a lengthwise direction. In the example illustrated in FIG. 8G, the elongated slits 55E can extend from near one end of the electrode 26 to near a second end of the electrode 26 in a widthwise direction.

[0129] As will be appreciated by one of skill in the art, by forming elongated slits 55E, 55F through the covering 54, a greater continuous surface area of the electrode 26 may be exposed which can help to increase the exposed conductive surface area of the electrode 26 but may also increase the likelihood of the coating 27 being rubbed while in use. Therefore, the spacing and size of the elongated slits 55E, 55F can be varied to help ensure the electrode 26 has a sufficient amount of surface area exposed while also ensuring the coating 27 is sufficiently protected.

[0130] FIG. 8H illustrates an example electrode 26 of a flexible polymer circuit strip 24 having apertures 55 which are elongated slits 55G formed through the covering 54. Unlike the elongated slits 55E, 55F illustrated in FIGS. 8F and 8G, the elongated slits 55G extend only a portion of the length of the electrode 26 (e.g., approximately less than ⅓ of the length of the electrode 26). In this way, the elongated slits 55G can be configured to provide greater mechanical protection to the coating 27 but still ensure a sufficient amount of the electrode 26 is exposed.

[0131] FIG. 8I illustrates an example electrode 26 of a flexible polymer circuit strip 24 having a combination of circular apertures 55A and elongated slits 55E. In this example, the elongated slits 55E can help to increase the exposed surface area of the electrode 26 while the circular apertures 55A can expose some of the surface area of the electrode 26 while also helping to provide greater mechanical protection to the coating 27. As will be appreciated by one of skill in the art, any of the example apertures 55A-55D and elongated slits 55E-55G can be combined to help ensure a sufficient amount of the electrode 26 is exposed while also ensuring the coating 27 is suitably protected.

[0132] Reference is now made to FIG. 8J, which is a table (Table 1) illustrating impedance values for example patterns of apertures 55 formed in the covering of the flexible polymer circuit strips of FIG. 7. Although Table 1 illustrates impedance values that were experimentally obtained for a few selected patterns of apertures 55, impedance values may also be obtained for any of the patterns of apertures 55 described herein. Thus, Table 1 should not be construed as limiting but is offered to illustrate the impedance values of a few example patterns of apertures 55.

[0133] As illustrated in FIG. 8J, the impedance values (in ohms) for six different aperture 55 patterns and two control samples (one with coating 27 covering approximately 100% of the electrode 26 surface and one without any coating 27) are shown at frequencies of 1 Hz, 10 Hz, 50 Hz, and 100 Hz. As illustrated, as the input frequency increases, the impedance generally decreases. Furthermore, the impedance values are inversely related to the exposed surface area. Illustrations of the six different aperture 55 patterns are shown below Table 1 for explanatory purposes.

[0134] Starting from left to right in table 1, impedance data of a first example electrode 26 (Example 1) having three rows of seven circular apertures 55A in each row is shown. The impedance of Example 1 can range from approximately 10,406 ± 920 ohms at 1 Hz to approximately 168 ± 28 ohms at 100 Hz. Example 2 similarly illustrates an electrode 26 having circular apertures 55A, however, Example 2 comprises two rows of five circular apertures 55A in each row. As shown, the impedance of Example 2 can range from approximately 12,502 ± 552 ohms at 1 Hz to approximately 206 ± 20 ohms at 100 Hz. As will be appreciated, because Example 2 has less surface area of the electrode 26 coated with the coating 27, the covering 54 covers a greater amount of the surface area of the electrode 26 and can be more mechanically robust since more covering 54 material can be located between each circular aperture 55A.

[0135] Continuing from left to right in Table 1, Example 3 illustrates an electrode 26 having four elongated slits 55E stretching from near one end of the electrode 26 to near a second end of the electrode 26. The impedance of Example 3 can range from approximately 7,000 ± 467 ohm at 1 Hz to approximately 109 ± 4 ohms at 100 Hz. Example 4 illustrates an electrode 26 having three rows of elongated slits 55G with each elongated slit 55G extending only a portion of the electrode 26 surface. In particular, Example 4 comprises three rows of three elongated slits 55G. The impedance of Example 4 can range from approximately 10,544 ± 235 ohms at 1 Hz to approximately 164 ± 8 ohms at 100 Hz. As will be appreciated, because the elongated slits 55G of Example 4 extend only a portion of the surface of the electrode 26, the coating 27 can be more mechanically protected by the covering 54 when compared to Example 3.

[0136] Example 5 and Example 6 in Table 1 illustrate electrodes 26 having an aperture 55 sized to expose approximately one-third and two-thirds of the electrode 26 respectively. As shown, the impedance value of Example 5 can range from approximately 16,921± 4,158 ohms at 1 Hz to 306 ± 77 ohms at 100 Hz while the impedance value of Example 6 can range from approximately 9,951 ± 407 ohms at 1 Hz to 186 ± 24 ohms at 100 Hz. As will be appreciated, although the impedance may be reduced by having a larger aperture size 55 as shown in Example 6, the coating 27 may have a greater tendency of being damaged because the covering 54 is less able to provide mechanical protection to the coating 27.

[0137] In the two far right columns of Table 1, impedance values for two control examples are included for reference. First, a control showing an electrode 26 having approximately 100% of its surface coated with the coating 27 is shown. In this example, the overall impedance can range from approximately 6,629 ± 197 ohms at 1 Hz to 117 ± 3 ohms at 100 Hz. In the second control example, an electrode having none of its surface coated with the coating 27 is shown. The impedance values for an electrode 26 not having any coating 27 can range from approximately 265,513 ± 9,186 ohms at 1 Hz to 3,636 ± 182 ohms at 100 Hz. As these two control examples illustrate, the coating 27 can help to significantly reduce the overall impedance of the electrode 26. However, as previously explained, the coating 27 can become damaged and eventually delaminate if the coating 27 is impacted by components of the basket catheter 10 or other objects. Thus, by forming apertures 55 through the covering 54 and then coating the electrode’s 26 surface with the coating 27, the disclosed technology can reduce the overall impedance while also helping to reduce the likelihood of damaging the coating 27.

[0138] 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.

[0139] 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.

[0140] 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.

[0141] 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.

[0142] 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.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] 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.

[0148] 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.

[0149] 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.

[0150] 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).

[0151] 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).

[0152] Reference is now made to FIG. 21, which illustrates an example method 100 of manufacturing a flexible polymer circuit strip 24 as described herein. The method 100 can include providing 102 an elongated resilient support element (e.g., elongated resilient support element 48), providing 104 a flexible polymer circuit (e.g., flexible polymer circuit strip 24), and providing 106 a yarn (e.g., yarn 52). The method can further include placing 108 the elongated resilient support element, the flexible polymer circuit, and the yarn together into a thermoplastic polymer resin shrink wrap (PET) (e.g., covering 54). The PET can then be heated 110 to shrink the PET around the elongated resilient support element, the flexible polymer circuit, and the yarn to at least partially enclose the elongated resilient support element, the flexible polymer circuit, and the yarn.

[0153] The method 100 can further include forming 112 a plurality of apertures through the PET to expose the surface of each electrode (e.g., electrode 26) on the flexible polymer circuit. As will be appreciated by one of ordinary skill in the art with the benefit of this disclosure, forming 112 the plurality of apertures through the PET can include any of the examples shown and described in this disclosure. For example, forming 112 the plurality of apertures through the PET can include forming circular apertures 55A as shown and described in relation to FIG. 8B. As another example, forming 112 the plurality of apertures through the PET can include forming elongated strips 55E as shown and described in relation to FIG. 8F. Forming 112 the plurality of apertures through the PET can further include any combination of the examples shown and described in this disclosure and any of the methods described herein.

[0154] FIG. 22 illustrates a catheter 200, in accordance another example of the disclosed technology. The catheter 200 can have a handle 202 and an elongated deflectable element 204 (a probe) having a proximal end 206 and a distal end 208. The handle 202 and the elongated deflectable element 204 can extend along a longitudinal axis L-L and have a lumen 210 extending therethrough. The lumen 210 can be sized to permit a catheter or other medical instrument to be inserted therethrough. For example, a physician can use the catheter 200 to navigate to an organ in a body of a patient and to position the distal end 208 of the catheter 200 in a location of interest within the organ. The physician can then insert another catheter or other medical instrument through the lumen 210 to deliver the second catheter or other medical instrument to the location of interest in the organ. In this way, the catheter 200 can act as a guiding sheath for guiding additional catheters to the location of interest in the organ.

[0155] To help ensure the distal end 208 of the catheter 200 can be navigated to the correct location, the catheter 200 can include a steerable end effector 220 that can be bent or otherwise articulated in a desired direction which can be controlled by a rotary knob 203 on the handle 202. The rotary knob 203, for example, can be connected to one or more pull wires, band, or any other suitable structures as will be apparent to those of skill in the art in view of the teaching herein. The end effector 220 can further include one or more electrode assemblies 230 disposed along the length of the end effector 220. For example, the end effector 220 can include at least a first electrode assembly 230 at a proximate end of the end effector 220 and a second electrode assembly 230 at a distal end of the end effector 230 as shown in FIG. 22. Electrode assemblies 230 can include one or more electrodes 232 and one or more magnetic position sensors 240 that can each be configured for determining a position and orientation of the end effector 220. Alternatively, one or more of the electrode assemblies 230 can be positioned at a distal end of the catheter 200 rather than on the end effector 220.

[0156] The electrodes 232, can be configured for impedance-based tracking. As will be appreciated by one of skill in the art, for impedance-based tracking, electrical current can be passed between electrodes 232 and electrode skin patches (not shown). The respective characteristics (e.g., impedance values) of the currents passing between electrodes 232 and electrode skin patches can be measured to determine the position coordinates of the catheter 200. Details of the impedance-based location tracking technology are described in U.S. Pat. Nos. 7,536,218; 7,756,576; 7,848,787; 7,869,865; and 8,456,182, each of which is incorporated herein by reference as if fully set forth herein.

[0157] In addition to being used to provide location sensing as described above, in some versions, electrodes 232 may be used to provide a reference signal during an EP mapping procedure, during an ablation procedure, or during any other kinds of procedures where blood impedance measurements may be useful. Such EP mapping procedures, ablation procedures, or other procedures may be performed via a catheter or some other instrument that is disposed in catheter 200. In some scenarios, electrodes 232 may contact tissue and may therefore pick up potentials from the tissue.

[0158] The electrodes 232 can include the same or similar features of the electrodes 26 described herein. That is, the electrodes 232 can include a covering 234 that can be disposed entirely over the electrodes 232, the magnetic position sensors 240, and much, if not all, of the rest of the end effector 220. The covering 234 can be a non-conductive polymer material or the covering 234 can be a conductive polymer material. As will be appreciated, covering the electrode 232 with a non-conductive polymer material can increase the impedance of the electrode and reduce the effectiveness of the impedance-based position tracking system due to less current being conducted to the electrode skin patches. In contrast, the conductive polymer material may permit sufficient current delivery from the electrodes 232 to utilize impedance-based position tracking.

[0159] In some examples, the covering 234 can have a plurality of apertures 236 formed therethrough. The aperture 236 can be formed by the same methods and have the same characteristics as the apertures 55 described herein previously (i.e., as described at least in relation to FIGS. 8A-8I). That is, the apertures 236 can have the same shape, be formed by the same method, and/or be formed such that the conductive surface of the electrode 234 being disposed a distance below an outer surface of the covering 234 such that the conductive surface and the outer surface are non-planar. Furthermore, the apertures 236 can have a conductive coating 238 placed over at least the portions of the electrode 232 exposed through the apertures 236. The coating 238 can be or include the same coating 27 described previously herein (i.e., as described at least in relation to FIGS. 8A-8I). As will be appreciated, the conductive coating 238 can help to reduce the overall impedance of the electrode 232. In some examples, the coating 238 can be applied to the exposed surface of the electrode 232 such that the overall impedance can be reduced by about 99% at low frequencies.

[0160] The magnetic position sensors 240 can be disposed around an outer perimeter of the electrode 232 as shown in FIG. 22. Alternatively, the magnetic position sensor 240 can be disposed underneath, beside, or partially around, underneath or beside the electrode 232. For example, the magnetic position sensor 240 can be a loop or coil of conductive material that is disposed in a circular or non-circular loop around a perimeter of the electrode 232. Alternatively, the magnetic position sensor 240 can be disposed at a location along the end effector 220 that is different than a location of the electrode 232. The magnetic position sensor 240 can be a magnetic based position sensor including three magnetic coils for sensing three-dimensional (3D) position and orientation. Magnetic position sensor 240 may be operated together with a location pad (not shown) including a plurality of magnetic coils configured to generate magnetic fields in a predefined working volume (e.g., a magnetic field generator). Real time position of the distal end 208 of catheter 200 can be tracked based on magnetic fields generated with location pad and sensed by magnetic position sensor 240. Details of the magnetic based position sensing technology are described in U.S. Pat. Nos. 5,391,199; 5,443,489; 5,558,091; 6,172,499; 6,239,724; 6,332,089; 6,484,118; 6,618,612; 6,690,963; 6,788,967; 6,892,091, each of which is incorporated herein by reference as if fully set forth herein.

[0161] Although not shown, it will be appreciated that the disclosed technology can be used in connection with a controller, such as a computer, that can be configured to receive signals from the skin patches and/or the magnetic position sensor 240 to determine a position and orientation of the end effector 220 as is known in the art. That is, signals from an impedance-based tracking system (including the electrodes 232) and signals from a magnetic-based position tracking system (including the magnetic position sensors 240) can be output to the controller and the controller can process the signals to correlate data generated from the signals into a position and orientation of the end effector 220. In this way, the position and orientation of the catheter 200 can be determined and output to a connected display so that a physician can ensure the catheter 200 is properly positioned.

[0162] In some examples, the electrodes 232 can be used in combination with the electrode skin patches (not shown) to generate position data based on impedance values and/or other characteristics associated with current flowing between electrodes 232 and the electrode skin patches, such impedance-based position data from electrodes 232 may be used in combination with the electromagnetic position data generated using the magnetic position sensors 240. For instance, in some scenarios the position data generated using the magnetic position sensors 240 may first be used to define an initial position matrix. Once that initial position matrix is defined based on the position data generated using the navigation sensor formed by magnetic position sensors 240, the position data generated using electrodes 232 may be used to further refine the initial position matrix that is defined from the electromagnetic position data generated using the magnetic position sensors 240. Alternatively, the electromagnetic-based position sensing data may be used in combination with the impedance-based position sensing data in any other suitable fashion.

[0163] Although described in relation to a catheter 200 having a lumen 210 extending therethrough, one of skill in the art will appreciated that the features of the electrode assembly 230 described herein can be applicable to other types of catheters. For example, the electrode assembly 230 can be applicable to basket catheters, planar catheters, lasso catheters, focal ablation catheters, etc. without departing from the scope of this disclosure.

[0164] 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%.

[0165] 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 subcombination.

[0166] 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 subcombinations 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.