Method of forming a spline using a flexible circuit component and an electrode assembly including the spline

Abstract

A method of forming a spline for an electrode assembly includes providing a structural member including a first surface and a second surface. The method further includes providing a flexible circuit assembly including a plurality of electrodes and at least one flexible circuit substrate having a contact surface and an outer surface opposite the contact surface. The plurality of electrodes are disposed on the outer surface of the at least one flexible circuit substrate. The method includes positioning the flexible circuit assembly relative to the structural member such that a first set of electrodes is aligned with the first surface and a second set of electrodes is aligned with the second surface. The method further includes coupling the at least one flexible circuit substrate to at least one of the structural member and the at least one flexible circuit substrate.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application Serial No. 63 / 021,737, filed May 8, 2020, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention generally relates to medical devices for use in the human body. In particular, the present invention relates to methods of forming splines for electrode assemblies using flexible circuit components. Background Art

[0004] Electrophysiology catheters are used in a variety of diagnostic, therapeutic, and / or mapping and ablation procedures to diagnose and / or correct conditions such as atrial arrhythmias, including, for example, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter.

[0005] Typically, to perform such diagnostic, therapeutic, and / or mapping and ablation procedures, a catheter is deployed and maneuvered through a patient's vasculature to a predetermined site, such as a site within the patient's heart. The catheter typically carries one or more electrodes that can be used, for example, for cardiac mapping or diagnosis, ablation, and / or other therapeutic delivery modalities, or for both, for example. Ablation therapy can be used to treat a variety of conditions affecting the human anatomy, including atrial or cardiac arrhythmias. When tissue is ablated or at least subjected to ablation energy generated by an ablation generator and delivered by an ablation catheter, a lesion is formed in the tissue. Electrodes mounted on or in the ablation catheter are used to create tissue cell necrosis in cardiac tissue to correct conditions such as atrial arrhythmias (including, but not limited to, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter). Cardiac arrhythmias can cause a variety of dangerous conditions, including loss of synchronous atrioventricular contraction and blood flow stasis. It is believed that the primary cause of atrial arrhythmias is stray electrical signals within the left or right atrium. The ablation catheter delivers ablation energy (e.g., radiofrequency energy, cryoablation, laser, chemicals, high-intensity focused ultrasound, etc.) to cardiac tissue to create a lesion in the cardiac tissue. This lesion disrupts unwanted electrical pathways, thereby limiting or preventing stray electrical signals that cause arrhythmias.

[0006] Electroporation is a non-thermal ablation technique that involves applying a strong electric field that induces the formation of pores in cell membranes. The electric field can be induced by applying pulses of relatively short duration, which can last, for example, from nanoseconds to several milliseconds. Such pulses can be repeated to form a pulse train. When such an electric field is applied to tissue in a in vivo environment, the cells in the tissue are affected by the transmembrane potential, which opens pores in the cell wall. Electroporation can be reversible (i.e., the temporarily opened pores will reseal) or irreversible (i.e., the pores will remain open), which results in cell destruction. For example, in the field of gene therapy, reversible electroporation is used to transfect high molecular weight therapeutic vectors into cells. In other therapeutic applications, appropriately configured pulse trains can be used alone to cause cell destruction, for example by causing irreversible electroporation.

[0007] Catheters (such as basket catheters and planar catheters) have electrodes distributed along a set number of splines. In particular, the electrodes are typically disposed on one side of each spline. Thus, the electrode density of at least some known catheters is limited by the number of splines and the number of electrodes disposed on each spline. Due to the inherent difficulty in increasing the number of splines, the electrode assembly can be limited to a set number of splines. For example, for a basket catheter, as the number of splines increases, the diameter of the electrode basket increases, which is undesirable because a larger electrode basket may be more difficult to deploy in a smaller target site. Alternatively, narrower splines can be used to maintain the diameter of the electrode basket, but the narrower splines limit the electrode size.

[0008] Additionally, at least some known catheters apply a positioning force only on one side of the catheter when deployed. For example, a helical catheter must be attached to only one point (e.g., at its proximal end), which results in the positioning force being applied only to one side of the helix. Thus, a force cannot be applied on the opposite side (e.g., 180° around the helix). SUMMARY OF THE INVENTION

[0009] The present invention relates to a method of forming splines for an electrode assembly for a catheter system. The method includes providing a structural member including a first surface and a second surface. The method further includes providing a flexible circuit assembly including a plurality of electrodes and at least one flexible circuit substrate having a contact surface and an outer surface opposite the contact surface. The plurality of electrodes are disposed on the outer surface of the at least one flexible circuit substrate. The method includes positioning the flexible circuit assembly relative to the structural member such that a first set of electrodes is aligned with the first surface and a second set of electrodes is aligned with the second surface. The method further includes coupling the at least one flexible circuit substrate to the structural member and at least one of the at least one flexible circuit substrate.

[0010] The present invention also relates to an electrode assembly for a catheter system. The electrode assembly has a longitudinal axis, a proximal end, and a distal end. The electrode assembly includes at least one spline that extends from the proximal end to the distal end of the electrode assembly. The at least one spline includes a structural member that extends from the proximal end to the distal end of the electrode assembly. The structural member includes a first surface and a second surface. The at least one spline further includes a flexible circuit assembly that includes a plurality of electrodes and at least one flexible circuit substrate having a contact surface and an outer surface opposite the contact surface. The plurality of electrodes are disposed on the outer surface of the at least one flexible circuit substrate. The flexible circuit assembly is positioned relative to the structural member such that a first group of the plurality of electrodes is aligned with the first surface of the structural member and a second group of the plurality of electrodes is aligned with the second surface of the structural member. The at least one flexible circuit substrate is coupled to the structural member and at least one of the at least one flexible circuit substrate.

[0011] The present invention also relates to a catheter system that includes a flexible catheter shaft, a handle coupled to the proximal end of the catheter shaft, and an electrode assembly. The electrode assembly is coupled to the distal end of the flexible catheter shaft and has a longitudinal axis, a proximal end, and a distal end. The electrode assembly includes at least one spline that extends from the proximal end to the distal end of the electrode assembly. The at least one spline includes a structural member that extends from the proximal end to the distal end of the electrode assembly. The structural member includes a first surface and a second surface. The at least one spline further includes a flexible circuit assembly that includes a plurality of electrodes and at least one flexible circuit substrate having a contact surface and an outer surface opposite the contact surface. The plurality of electrodes are disposed on the outer surface of the at least one flexible circuit substrate. The flexible circuit assembly is positioned relative to the structural member such that a first group of the plurality of electrodes is aligned with the first surface of the structural member and a second group of the plurality of electrodes is aligned with the second surface of the structural member. The at least one flexible circuit substrate is coupled to the structural member and at least one of the at least one flexible circuit substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Schematic diagrams and block diagrams of catheter systems incorporating embodiments of the present invention.

[0013] Figure 2 is Figure 1 A simplified block diagram and schematic diagram of an exemplary visualization, navigation, and / or mapping system for the catheter system shown.

[0014] Figure 3 is applicable to Figure 1 A perspective view of an exemplary electrode assembly for the system, shown in the form of a basket electrode assembly.

[0015] Figure 4 Another exemplary electrode assembly suitable for Figure 1 the system, shown in the form of a planar electrode assembly.

[0016] Figure 5 Another exemplary electrode assembly suitable for Figure 3 and Figure 4 end view of an exemplary spline of the electrode assembly shown.

[0017] Figure 6 Another exemplary sub-component of a flexible circuit assembly suitable for forming Figure 5 a spline, shown in a top view.

[0018] Figure 7 Steps in an exemplary method of forming Figure 5 a spline are shown.

[0019] Figure 8 Another exemplary electrode assembly suitable for Figure 3 and Figure 4 end view of another exemplary spline of the electrode assembly shown.

[0020] Figure 9 An exemplary flexible circuit assembly suitable for forming Figure 8 a spline is shown.

[0021] Figure 10 Steps in an exemplary method of forming Figure 8 a spline are shown.

[0022] Figure 11 Steps in an exemplary method of forming Figure 8 a spline are shown, and another subsequent step is shown.

[0023] Figure 12 Another exemplary electrode assembly suitable for Figure 3 and Figure 4 end view of another exemplary spline of the electrode assembly shown.

[0024] Figure 13 Steps in an exemplary method of forming Figure 12 a spline are shown.

[0025] Figure 14 Another exemplary sub-component of the system suitable for Figure 1 is shown in a perspective view in a spiral configuration.

[0026] Figure 15 A flowchart of an exemplary method of forming a spline for an electrode assembly (such as Figure 3 and Figure 4 the electrode assemblies shown) is shown.

[0027] In the various views of the drawings, corresponding reference numerals indicate corresponding parts. It is to be understood that the drawings are not necessarily to scale. Detailed Description

[0028] The present invention generally relates to medical devices for use in the human body. The present invention provides a medical device including a spline having an electrode assembly for a catheter system and a method of forming the spline for use in medical procedures in the human vasculature, such as mapping and / or ablation procedures. The electrode assembly of the present invention includes at least one spline including a structural member and a flexible circuit assembly. The flexible circuit assembly includes at least one flexible circuit substrate and a plurality of electrodes disposed on an outer surface of the at least one flexible circuit substrate. The flexible circuit assembly is positioned relative to the structural member such that the electrodes are aligned with both a first surface and a second surface of the structural member. At least some known electrode assemblies include a spline formed by positioning a structural member within a tubing and subsequently disposing electrodes on an outer surface of the tubing.

[0029] Unlike some known electrode assemblies, the disclosed embodiments are capable of forming a spline by directly coupling the electrodes to one or more surfaces of the structural member via the flexible circuit substrate, thereby eliminating the need for an intermediate tubing. Additionally, the disclosed embodiments are capable of disposing electrodes on two or more surfaces of a single spline, thereby enabling more electrodes to be disposed on a single spline. Such an arrangement increases the electrode density circumferentially around the electrode assembly, which can improve the accuracy of mapping and / or ablation procedures and thus result in more consistent and improved medical outcomes.

[0030] Reference is now made to the drawings, Figure 1 FIG. 13 is a schematic and block diagram of a catheter system 100 suitable for diagnostic purposes, anatomical mapping, and / or ablation therapy, such as electropermeabilization therapy. Generally, the embodiments each include an electrode assembly disposed at the distal end of a catheter shaft. As used herein, "proximal" refers to the direction toward the end of the catheter closer to the clinician, and "distal" refers to the direction away from the clinician and (generally) within the individual's body. The electrode assembly includes one or more individual, electrically isolated electrode elements. Each electrode element (also referred to herein as a catheter electrode) is individually wired such that it can be selectively paired or combined with any other electrode element to act as a bipolar or multipolar electrode.

[0031] System 100 can be used for irreversible electroporation to destroy tissue. In particular, System 100 can be used for electroporation-induced primary necrosis therapy, which refers to the effect of delivering an electric current in a manner that directly causes an irreversible loss of plasma membrane (cell wall) integrity, resulting in its rupture and cell necrosis. This mechanism of cell death can be regarded as an "outside-in" process, meaning that the disruption of the outer cell wall has an adverse effect on the interior of the cell. Typically, for classical plasma membrane electroporation, the electric current is delivered as a pulsed electric field (i.e., pulsed electric field ablation (PFA)) in the form of short-duration pulses (e.g., having a duration of 0.1 to 20 milliseconds (ms)) between closely spaced multiple electrodes capable of delivering an electric field strength of about 0.1 to 1.0 kilovolts per centimeter (kV / cm).

[0032] System 100 includes an electrode assembly 102, which includes at least one catheter electrode configured to be used as described below. The electrode assembly 102 is incorporated as part of a medical device, such as a catheter 104 for electroporation therapy, diagnosis, mapping, and / or therapeutic procedures. For example, the electrode assembly 102 can be used to map one or more structures 106 (also referred to herein as internal body structures 106) within a patient's body 108. As another example, the electrode assembly 102 can be used for ablation therapy (such as electroporation therapy) of the tissue of a structure 106 in the body 108. In the illustrated embodiment, the structure 106 includes a patient's vasculature and / or the heart or heart tissue. However, it should be understood that the embodiments can be used for mapping, diagnosis, and / or ablation therapy for a variety of other body structures and / or tissues.

[0033] System 100 also includes additional subsystems, such as a power source 110 and a visualization, navigation, and mapping system 112 for visualization, mapping, and navigation of the internal body structure 106. The power source 110 is any power source configured to energize or excite the electrodes of the electrode assembly 102 and / or generate an electric field and / or a magnetic field to perform appropriate functions during a medical procedure. For example, the power source 110 includes a radio frequency (RF) ablation and / or electroporation generator to allow System 100 to be used for RF ablation and electroporation procedures. In such embodiments, the power source 110 is configured to energize the electrodes according to an ablation strategy, which can be predetermined or user-selectable. When used for RF ablation procedures, the power source 110 outputs radio frequency (RF) energy to the catheter 104 via a cable 114. The RF energy (e.g., using bipolar electrode stimulation) exits the catheter 104 through the electrodes of the electrode assembly 102. The dissipation of the radio frequency energy in the body increases the temperature near the electrodes, thereby allowing RF ablation to occur.

[0034] In some embodiments, system 100 includes one or more return electrodes 116 (e.g., patch electrodes) for monopolar electrode stimulation or performing mapping functions, as further described herein. In such embodiments, power supply 110 includes a signal generator coupled to patch electrode 116 and configured to excite patch electrode 116 to generate an electric field within body 108.

[0035] In the illustrated embodiment, catheter 104 includes a cable connector or interface 118, a handle 120, and a shaft 122 having a proximal end 124 and a distal end 126. Catheter 104 may also include other conventional components not shown herein, such as one or more sensors (e.g., sensor 138), additional electrodes, and corresponding conductors or wires. Connector 118 provides mechanical and electrical connection(s) for cable(s) 114 extending from power supply 110 and / or visualization, navigation, and mapping system 112, and is disposed at the proximal end of catheter 104 as shown.

[0036] Handle 120 provides a means for a clinician to hold the position of catheter 104 and may further provide a mechanism for steering or guiding shaft 122 within body 108. For example, handle 120 may include a mechanism for changing the length of one or more guide wires extending through catheter 104 to the distal end 126 of shaft 122 or for steering shaft 122. Additionally, in some embodiments, handle 120 may be configured to change the shape, size, and / or orientation of a portion of the catheter. It should be understood that the construction of handle 120 may vary. In an alternative exemplary embodiment, catheter 104 may be robotically driven or controlled. Thus, rather than a clinician manipulating the handle to advance / retract and / or steer or guide catheter 104 (especially its shaft 122), a robot is used to manipulate catheter 104.

[0037] Shaft 122 is an elongated, tubular, flexible member configured for movement within body 108. Shaft 122 is configured to support electrode assembly 102 as well as to contain associated conductors and possibly additional electronics for signal processing or conditioning. Shaft 122 may also permit the delivery, delivery, and / or removal of fluids (including flush and body fluids), drugs, and / or surgical tools or instruments. Shaft 122 may be made of a conventional material such as polyurethane and defines one or more lumens configured to accommodate and / or convey electrical conductors, fluids, or surgical tools. Shaft 122 may be guided into a blood vessel or other structure 106 within body 108 through a conventional introducer. Shaft 122 may then be advanced, retracted, and / or steered or guided through body 108 to a desired location within structure 106, including by using a guide wire or other mechanisms known in the art.

[0038] In an embodiment of the present invention, the electrode assembly 102 is coupled to the distal end 126 of the shaft 122 to deliver the electrode assembly 102 to a target location within the patient's body 108. In some embodiments, the electrode assembly 102 is an electrode basket that is selectively configurable between a collapsed configuration and an expanded configuration. For example, the electrode assembly 102 can be delivered to a target location (e.g., within a catheter shaft 122 and / or within a separate catheter not specifically shown) in a collapsed configuration. In this example, the electrode assembly 102 is then deployed into an expanded configuration at the target location to perform a medical procedure (e.g., an ablation or mapping procedure). In some embodiments, the electrode assembly 102 is in the form of a planar or grid electrode assembly that includes a paddle coupled to a catheter body. In an embodiment of the present invention, the electrode assembly 102 is subsequently energized using a power source 110 to perform a medical procedure at the target location. The electrode assembly 102 may include a plurality of electrodes thereon (e.g., such as Figures 3 to 5 226 shown). The electrode assembly 102 and / or catheter shaft 122 may include one or more sensors 138 therein or thereon.

[0039] The sensors 138 mounted in or on the shaft 122 and / or in or on the electrode assembly 102 can be used for various diagnostic and therapeutic purposes, including, for example, electrophysiological studies and cardiac mapping. In an embodiment, one or more sensors 138 are provided to perform position sensing functions. More particularly, one or more sensors 138 are configured as positioning sensors that provide information related to the position (e.g., position and orientation) of the catheter 104 and its distal end 126 to, for example, a visualization, navigation, and mapping system 112, particularly at a particular time point. The sensor 138 may include one of a variety of types of sensors, such as, for example, but not limited to, an electrode (e.g., a tip electrode and a ring electrode) or a magnetic sensor (e.g., a magnetic coil). It should be understood that the number, shape, orientation, and purpose of the sensors may vary.

[0040] A visualization, navigation, and mapping system 112 may be provided for visualization, mapping, and navigation of the internal body structure 106, for example by determining the locations of the electrode assembly 102, one or more splines, and / or specific electrodes thereon. These locations may be projected onto a geometric anatomical model. The visualization, navigation, and mapping system 112 may include conventional equipment known in the art (e.g., EnSite 3D from Abbott Laboratories, USA). TM Velocity TM or EnSite TM Precision TM Cardiac Mapping and Visualization System, or EnSite TM NavX TMThe system, commercially available from Abbott in the United States, and as described in U.S. Patent No. 7,263,397 jointly assigned to the reference titled "Method and Apparatus for Catheter Navigation and Location and Mapping in the Heart", the entire disclosure of which is incorporated herein by reference). Other systems and components suitable for the visualization, navigation, and mapping system 112 are described, for example, in U.S. Patent No. 7,885,707 titled "Method of Scaling Navigation Signals to Account for Impedance Drift in Tissue" and U.S. Patent Application Publication No. 2018 / 0296111 titled "Orientation Independent Sensing, Mapping, Interface and Analysis System and Methods", the entire disclosures of which are incorporated herein by reference. In various embodiments, the visualization, navigation, and mapping system 112 uses the electrodes of the electrode assembly 102 as bipolar pairs for the visualization, mapping, and navigation of the internal body structure 106. However, it should be understood that the system is exemplary in nature and not restrictive. Other techniques for visualizing / navigating / mapping catheters in space are known, including, for example, the CARTO navigation and location system of Biosense Webster, Inc., the system, commonly available fluoroscopy systems, or systems such as the gMPS system of Mediguide Ltd. In this regard, some positioning, navigation, and / or visualization systems will provide sensors for generating signals indicative of catheter position information and may include, for example, one or more electrodes in the case of impedance-based positioning systems or, alternatively, one or more coils (i.e., windings) configured to detect one or more characteristics of a magnetic field in the case of magnetic field-based positioning systems.

[0041] System 100 may also include a host computer system 130, which in some embodiments may be integrated with the visualization, navigation, and mapping system 112. The computer system 130 may include an electronic control unit (ECU) 132 and a memory 134. The computer system 130 also includes a display device 136, which may be integrated into the computer system 130 and / or coupled to the computer system 130. The catheter 104 and thus the electrode assembly 102 may be coupled to the computer system 130 and / or the visualization, navigation, and mapping system 112 via a wired or wireless connection.

[0042] Figure 2 A simplified block diagram and schematic illustration of the visualization, navigation, and / or mapping system 112 for the system 100 ( Figure 1 shown therein). Referring to Figure 1 and Figure 2 , the visualization, navigation, and mapping system 112 may include a plurality of patch electrodes 116, an ECU 132, a display device 136, and other components. In addition to the patch electrodes 116 referred to as "abdominal patches" B , the patch electrodes 116 are configured to generate electrical signals for, for example, determining the position and orientation of the catheter 104 and for guiding it. In one embodiment, the patch electrodes 116 are orthogonally placed on the surface of the patient's body 108 and are used to generate a specific axis electric field within the body 108. For example, in one embodiment, the patch electrodes 116 X1 , 116 X2 may be placed along a first (x) axis. The patch electrodes 116 Y1 , 116 Y2 may be placed along a second (y) axis, and the patch electrodes 116 Z1 , 116 Z2 may be placed along a third (z) axis. In other embodiments, the generated dipoles (e.g., the dipole between electrodes 116 X1 and 116 Y1 ) may not be on the axis. Each of the patch electrodes 116 may be coupled to a multiplexer switch 140. In one embodiment, the ECU 132 is configured via appropriate software to provide control signals to the switch 140 to sequentially couple pairs of the electrodes 116 to a signal generator (e.g., a power supply 110). The excitation of each pair of electrodes 116 generates an electric field within the body 108 and in regions of interest such as the patient's heart. The voltage levels at the non-excited electrodes 116 of the abdominal patch 116 B are filtered by, for example, a low-pass filter 142, converted by an analog-to-digital converter 144, and provided to the ECU 132 as a reference value.

[0043] As described above, catheter 104 includes electrode assembly 102 coupled thereto. In an embodiment, electrode assembly 102 includes a plurality of splines, each spline including one or more electrodes mounted therein or thereon (e.g., electrode 414 as shown in Figures 5 to 13 ), and in some embodiments, these electrodes are electrically coupled to power supply 110 and / or ECU 132 to achieve one or more diagnostic or therapeutic purposes as described herein. In an embodiment, electrode assembly 102 is placed within an electric field generated in body 108 by excitation patch electrodes 116. When placed in the electric field, the voltage experienced by the electrodes on electrode assembly 102 depends on their position between patch electrodes 116 and the position of each electrode relative to the tissue of the anatomically mapped structure 106. A comparison of the voltage measurements made between each electrode on electrode assembly 102 and patch electrodes 116 can be used to determine the position of each electrode on electrode assembly 102 relative to anatomically mapped structure 106. This position information can then be used by ECU 132, for example, to generate models such as surface models and / or maps of the anatomically mapped structure, or corresponding to the surface models and / or maps of the anatomically mapped structure. Thus, as catheter 104 is moved along the surface of the desired anatomically mapped structure 106, for example, electrode assembly 102 can be used to collect position data points corresponding to the positions of the electrodes thereon and thus can be used to collect position data points corresponding to the surface of anatomically mapped structure 106. These position data points can then be used by ECU 132, for example, to generate or construct a surface model of the anatomically mapped structure. Additionally, the information received from electrode assembly 102 can also be used to display the position and orientation of electrode assembly 102 and / or the tip of catheter 104 on a display device such as display device 136. Thus, ECU 132 of visualization, navigation, and mapping system 112 provides means for generating a display signal and other means for controlling display device 136 and creating a graphical user interface (GUI) on display device 136.

[0044] ECU 132 can include, for example, a programmable microprocessor or microcontroller, or can include an application specific integrated circuit (ASIC). ECU 132 can include a central processing unit (CPU) and an input / output (I / O) interface through which ECU 132 can receive a plurality of input signals, including, for example, signals generated by electrode assembly 102. ECU 132 can also generate a plurality of output signals, including, for example, signals for controlling display device 136. ECU 132 can be configured to perform various functions, such as those described herein, using appropriate programming instructions or code. Thus, in one embodiment, ECU 132 is programmed with one or more computer programs encoded on a computer-readable storage medium to perform the functions described herein.

[0045] The ECU 132 can be configured to construct a geometric anatomical model of the structure 106 for display on the display device 136. The ECU 132 can also be configured to generate a GUI through which a user can view the geometric anatomical model and / or control the electrode assembly 102 and other aspects. The anatomical model can include a three-dimensional (3-D) model or a two-dimensional (2-D) model. To display the data and images generated by the ECU 132, the display device 136 can include one or more conventional computer monitors or other display devices known in the art.

[0046] Figure 3 A perspective view of an exemplary electrode assembly 102 suitable for use in the system 100, shown in the form of a basket electrode assembly 200. The basket electrode assembly 200 includes a basket 202 coupled to a catheter body 204 (e.g., a shaft 122) via a suitable proximal connector 206. The basket 202 includes a plurality of splines 208 and a distal connector 210, with each spline 208 terminating at the distal connector 210. In some embodiments, such as the illustrated embodiment, the basket electrode assembly 200 can also include a flush tube 212 (e.g., for supplying fluid to the basket electrode assembly 200). In other embodiments, the flush tube 212 can be omitted. Each of the plurality of splines 208 includes at least one electrode 214. Although each spline 208 can include more or fewer than eight electrodes 214, in the illustrated embodiment, each of the plurality of splines includes eight electrodes 214.

[0047] The electrode 214 can be used for various diagnostic and therapeutic purposes, including but not limited to cardiac mapping and / or ablation (such as radiofrequency ablation or irreversible electroporation (IRE) ablation). For example, in some embodiments, the electrode assembly 200 can be configured as a bipolar electrode assembly for bipolar electroporation therapy. Specifically, the electrodes 214 can be individually electrically coupled to an electroporation generator, such as the power supply 110 (e.g., via suitable wires or other suitable electrical conductors extending through the catheter shaft 122), and can be configured to be selectively energized with opposite polarities (e.g., by the power supply 110 and / or the computer system 130) to generate an electric potential and a corresponding electric field therebetween for IRE therapy. That is, one of the electrodes 214 can be configured to act as a cathode, while the other of the electrodes 214 can be configured to act as an anode. The electrodes 214 can be any suitable electroporation electrodes. The electrodes 214 can have any other shape or configuration. It is recognized that the shape, size, and / or configuration of the electrodes 214 may affect various parameters of the applied electroporation therapy. For example, increasing the surface area of one or more of the electrodes 214 can reduce the applied voltage required to cause the same level of tissue damage. In various embodiments, any combination of the electrodes 214 can be configured as an electrode pair, including for example but not limited to adjacent electrodes, non-adjacent electrodes, electrodes on adjacent splines, electrodes on non-adjacent splines, and any other combination of electrodes that enables the functionality of the system 100 as described herein. In some embodiments, as described above, the power supply 110 is configured to energize the electrodes according to an ablation strategy.

[0048] Figure 4 FIG. 4 is a perspective view of another exemplary electrode assembly 102 suitable for use with the system 100, shown in the form of a planar electrode assembly 300. The planar electrode assembly 300 includes a paddle 302 coupled to a catheter body 304 (such as the shaft 122). In the illustrated embodiment, the catheter body 304 includes body electrodes 306, 308, and 310 coupled thereto. In the illustrated embodiment, the paddle 302 includes a first spline 312, a second spline 314, a third spline 316, and a fourth spline 318, which are coupled to the catheter body 304 via a proximal connector and to each other via a distal connector at the distal end of the paddle 302. In one embodiment, the first spline 312 and the fourth spline 318 can be one continuous segment, and the second spline 314 and the third spline 316 can be another continuous segment. In other embodiments, the various splines can be separate segments coupled to each other. The first spline 312, the second spline 314, the third spline 316, and the fourth spline 318 are generally aligned in the same (topological) plane. Although the paddle 302 is in Figure 4is illustrated as being relatively flat or planar, but it should be understood that the paddle 302 can be bent, curled, warped, twisted, and / or otherwise deformed. Accordingly, the plane defined by the paddle 302 and the splines 312, 314, 316, and 318 can be correspondingly deformed such that the plane is a non-flat topological plane. In the illustrated embodiment, the planar electrode assembly 300 further includes a flush port 320 located at the distal end of the catheter body 304. The flush port 320 is positioned to deliver a flush agent to a portion of one or more of the splines 312 - 318.

[0049] The plurality of splines may further include a different number of electrodes 322. The electrodes in the illustrated embodiment may include unipolar electrodes or electrodes printed on a flexible bendable material. The electrodes may be evenly spaced along one or more surfaces of the spline. In other embodiments, the electrodes may be evenly or unevenly spaced, and the electrodes may include any other suitable type of electrode.

[0050] The electrodes 322 can be used for a variety of diagnostic and therapeutic purposes, including but not limited to cardiac mapping and / or ablation (e.g., radiofrequency ablation or IRE ablation). For example, in some embodiments, the electrode assembly 300 can be configured as a bipolar electrode assembly for bipolar electroporation therapy. Specifically, the electrodes 322 can be individually electrically coupled to an electroporation generator, such as the power supply 110 (e.g., via suitable wires or other suitable electrical conductors extending through the catheter shaft 122), and can be configured to be selectively energized with opposite polarities (e.g., by the power supply 110 and / or the computer system 130) to generate an electric potential and a corresponding electric field therebetween for IRE therapy. That is, one of the electrodes 322 can be configured to act as a cathode, while another of the electrodes 322 can be configured to act as an anode. The electrodes 322 can be any suitable electroporation electrodes. The electrodes 322 can have any other shape or configuration. It is recognized that the shape, size, and / or configuration of the electrodes 322 may affect various parameters of the applied electroporation therapy.

[0051] Figure 5 A end view of an exemplary spline 400 suitable for the electrode assemblies described herein (e.g., electrode assemblies 102, 200, and 300) is shown. In particular, the spline 400 can be incorporated into the basket electrode assembly 200 as one or more of the splines 208 (all shown in Figure 3 ). Additionally or alternatively, the spline 400 can be incorporated into the planar electrode assembly 300 as one or more of the splines 312, 314, 316, and 318 (all shown in Figure 4 ). In the illustrated embodiment, the spline 400 includes a flexible circuit assembly 402 and a structural member 404. The structural member 404 extends from the proximal end 401 of the spline 400 to the distal end ( Figure 5(not shown in the figure), and generally provides structural support for the spline 400 and its components (such as the flexible circuit assembly 402). The structural member 404 includes a first surface 406 and a second surface 408 (both shown in Figure 7 the figure). In the illustrated embodiment, the structural member 404 has a rectangular cross-section, and the first surface 406 and the second surface 408 are located on opposite sides of the structural member 404. In other embodiments, the structural member 404 may have a cross-sectional shape other than rectangular, and the first surface 406 and the second surface 408 may be on non-opposite sides of the structural member 404. Additionally, in an embodiment, the structural member 404 is a single continuous member that extends the entire length of the spline 400 (i.e., from the proximal end 401 to the distal end).

[0052] The structural member 404 can be made of various suitable materials, including but not limited to metal alloys, stainless steel, copper-aluminum-nickel alloys, alloys including zinc, copper, gold, and / or iron, polymers including any of the above materials, shape memory polymers, and / or combinations thereof. In some embodiments, the structural member 404 can be made of a non-metallic material such as a formed rigid plastic material. In an embodiment, the structural member 404 is made of a shape memory alloy. A particularly preferred shape memory alloy for use is Nitinol, a nickel-titanium (NiTi) alloy. Nitinol is an approximately stoichiometric alloy of nickel and titanium, which may also include small amounts of other metals to obtain desired properties. Nickel-titanium alloys are very elastic and are commonly referred to as "superelastic" or "pseudoelastic". Such shape memory alloys tend to have a temperature-induced phase change, which will cause the material to have a preferred form that can be fixed by inducing a phase change in the material by heating the material above a certain transition temperature. When the alloy cools down, the alloy will "recover" to its shape during the heat treatment process and will tend to assume that form unless restricted from doing so.

[0053] The flexible circuit assembly 402 includes at least one flexible circuit designed to bend or flex during use and is typically mounted on a flexible substrate. In the illustrated embodiment, the flexible circuit assembly 402 includes a first sub-assembly 410 and a second sub-assembly 412. Figure 6 Top views of the first and second sub-assemblies of the flexible circuit assembly 402 ( Figure 5 shown in the figure). Although in other embodiments, the first sub-assembly 410 and the second sub-assembly 412 may have different configurations, in the illustrated embodiment, the first sub-assembly 410 and the second sub-assembly 412 are the same. Referring to Figure 5 and Figure 6 , each of the first sub-assembly 410 and the second sub-assembly 412 includes a plurality of electrodes 414 provided on a flexible circuit substrate 416. Each flexible circuit substrate 416 in the sub-assemblies 410, 412 includes a contact surface (such as an inner surface) 420 ( Figure 7The opposite outer surfaces 418 (shown in [reference]). Each flexible circuit substrate 416 further includes a first longitudinal edge 422 and a second longitudinal edge 424. In one embodiment, the flexible circuit substrate 416 is a flexible printed circuit, such as a polyimide flexible circuit. In one example, the flexible circuit substrate 416 can be Kapton polyimide flexible circuit.

[0054] The electrodes 414 are disposed on the outer surface 418 of each flexible circuit substrate 416. The electrodes 414 can be any suitable type of electrode, such as a single-sided electrode disposed on the outer surface 418 or an electrode printed on the flexible circuit substrate 416. In an exemplary embodiment, the first subassembly 410 and the second subassembly 412 each include a single flexible circuit that includes electrodes on one side of the flexible circuit. Although other embodiments may include more or fewer than 12 electrodes, the illustrated embodiment includes 12 electrodes disposed on the outer surface 418. For example, the first subassembly 410 and the second subassembly 412 can include any suitable number of electrodes that enable the functions of the system 100 to operate as described herein. In one example, the spline 400 can include eight to twelve electrodes on each subassembly 410, 412. Additionally, in the illustrated embodiment, the electrodes 414 are rectangular or approximately rectangular (i.e., a rounded rectangle). In other embodiments, the electrodes 414 can have any suitable shape or configuration that enables the functions of the spline 400 to operate as described herein, including, for example, but not limited to, circular or spherical. The plurality of electrodes 414 of the first subassembly 410 are interchangeably referred to herein as the first set of electrodes, and the plurality of electrodes 414 of the second subassembly 412 are interchangeably referred to herein as the second set of electrodes.

[0055] Figure 7 Steps 500 in an exemplary method of forming the spline 400 are shown ( Figure 5 shown in [reference]). Referring to Figures 5 to 7 , an exemplary method of forming the spline 400 includes positioning the structural member 404 between the first subassembly 410 and the second subassembly 412 such that the electrodes 414 (e.g., the first set of electrodes) of the first subassembly 410 are aligned with the first surface 406 of the structural member 404, and the electrodes 414 (e.g., the second set of electrodes) of the second subassembly 412 are aligned with the second surface 408 of the structural member 404. The exemplary method further includes coupling the flexible circuit substrates 416 to each other at their respective first edges 422 and their respective second edges 424, as shown by the arrow 426 in Figure 7 . The flexible circuit substrates 416 can be joined using an adhesive material 428 (as shown in Figure 5are joined at their respective first edges 422 and respective second edges 424. In one embodiment, an opening (e.g., a gap in space) formed by joining the respective first edges 422 and the respective second edges 424 may be completely filled with an adhesive material 428. The adhesive material 428 may be applied on the contact surfaces 420 of one or both of the flexible circuit substrates 416. The adhesive material 428 may be a biocompatible adhesive or any suitable material for bonding the flexible circuit substrates 416 together. In other embodiments, the flexible circuit substrates 416 are heat-sealed together.

[0056] In certain embodiments, the flexible circuit substrates 416 are only joined to each other and are not fixed to the structural member 404. For example, the flexible circuit substrates 416 of the first subassembly 410 and the second subassembly 412 may be joined only at their respective first edges 422 and second edges 424 such that the joined flexible circuit substrates 416 are free to move and slide relative to the structural member 404. In other embodiments, one or both of the flexible circuit substrates 416 are directly joined to the structural member 404 at the first surface 406 and / or the second surface 408. In an embodiment, the structural member 404 is sandwiched between two separate subassemblies 410, 412 to form a bilateral spline of the electrode 414.

[0057] Figure 8 shows an end view of another exemplary spline 600 suitable for use in the electrode assembly 102 ( Figure 1 shown in). In particular, the spline 600 may be incorporated into the basket electrode assembly 200 as one or more splines 208 (both shown in Figure 3 shown in). Additionally or alternatively, the spline 600 may be incorporated into the planar electrode assembly 300 as one or more of the splines 312, 314, 316, and 318 (all shown in Figure 4 shown in). As described above, the spline 600 may be substantially similar to the spline 400 or have a configuration substantially the same as the spline 400. The spline 600 includes a structural member 404 and a flexible circuit assembly 602. The structural member 404 extends from the proximal end 601 of the spline 600 to a distal end (not shown). The flexible circuit substrates 416 may be joined together using an adhesive material 428. In one embodiment, an opening (e.g., a gap in space) formed by joining the flexible circuit substrates 416 may be completely filled with the adhesive material 428.

[0058] Figure 9 is a top view of the flexible circuit assembly 602 for the spline 600 ( Figure 8 shown in). Referring to Figure 8 and Figure 9, the flexible circuit assembly 602 includes a first sub-assembly 410 and a second sub-assembly 412. Each of the sub-assemblies 410, 412 includes a plurality of electrodes 414 disposed on an outer surface 418 of a flexible circuit substrate 416. In Figure 8 and Figure 9 the illustrated embodiment, the first sub-assembly 410 and the second sub-assembly 412 of the flexible circuit assembly 602 are joined together at a fold line 604. The fold line 604 may include any weakened line, such as a score line, a break line, a crease, a perforation line, and combinations thereof, that facilitates folding or bending of the joined sub-assemblies 410, 412 at the fold line 604.

[0059] Figure 10 Steps 700 in an exemplary method of forming a spline 600 using the flexible circuit assembly 602 are shown ( Figure 8 shown in). As Figure 10 shown, an exemplary method of forming a spline 600 includes positioning a structural member 404 adjacent to a contact surface 420 proximate to the sub-assemblies 410, 412 such that the structural member 404 is close to the fold line 604. Figure 11 Another subsequent step 800 in an exemplary method of forming a spline 600 is shown. As Figure 11 shown, an exemplary method of forming a spline 600 further includes folding the flexible circuit assembly 602 about the fold line 604 and around the structural member 404 such that the electrodes 414 (e.g., a first set of electrodes) of the first sub-assembly 410 are coupled adjacent to a first surface 406 of the structural member 404, and the electrodes 414 (e.g., a second set of electrodes) of the second sub-assembly 412 are coupled adjacent to a second surface 408 of the structural member 404. An exemplary method of forming a spline 600 further includes coupling the flexible circuit substrates 416 of the sub-assemblies 410, 412 to each other at a longitudinal edge 606 of the flexible circuit assembly 602, as Figure 10 shown by arrow 608 in. As Figure 8 shown, the flexible circuit substrates 416 may be coupled at the edge 606 using an adhesive material 428. In some embodiments, the flexible circuit substrates 416 of the first sub-assembly 410 and the second sub-assembly 412 are coupled only to each other and not fixed to the structural member 404. For example, the flexible circuit substrates 416 of the first sub-assembly 410 and the second sub-assembly 412 may be coupled only at the longitudinal edge 606 such that the coupled flexible circuit substrates 416 are free to move and slide relative to the structural member 404. In other embodiments, one or both of the flexible circuit substrates 416 are directly coupled to the structural member 404 at the first surface 406 and / or the second surface 408.

[0060] Figure 12 shown is applicable to the electrode assembly 102 ( Figure 1An end view of another exemplary spline 900 (shown in Figure 3 is incorporated into the basket electrode assembly 200 as one or more of the splines 208 (all shown in Figure 4 . Additionally or alternatively, the spline 900 may be incorporated into the planar electrode assembly 300 as one or more of the splines 312, 314, 316, and 318 (all shown in Figure 5 ). The spline 900 includes a structural member 404 and a flexible circuit assembly 902. The structural member 404 was described above with respect to the spline 400 ( Figure 8 shown in) and the spline 600 ( Figure 13 shown in Figure 12 ). Figure 12 and Figure 13 , the flexible circuit assembly 902 of the spline 900 includes a flexible tubular substrate 904 that defines a cavity 906 therein. In one embodiment, the flexible tubular substrate 904 is a flexible printed circuit formed in the shape of a compressible cylindrical tube.

[0061] A plurality of electrodes 414 are disposed on the outer surface 908 of the flexible tubular substrate 904. The electrodes 414 may have the same configuration as described above with reference to the spline 400 ( Figure 5 shown in) and the spline 600 ( Figure 8 shown in). The flexible circuit assembly 902 includes two sets of electrodes 414 (a first set of electrodes and a second set of electrodes) disposed on opposite sides of the flexible tubular substrate 904. Each set of electrodes 414 may include any suitable number of electrodes 414 that enable the spline 900 to function as described herein. For example, each set of electrodes 414 may include eight to twelve electrodes.

[0062] As Figure 13 shown, an exemplary method of forming the spline 900 includes inserting the structural member 404 into the cavity 906 of the flexible tubular substrate 904. The exemplary method of forming the spline 900 further includes compressing the flexible tubular substrate 904 (e.g., by applying a force to the outer surface 908) such that a first set of electrodes 414 of the flexible circuit assembly 902 are coupled adjacent a first surface 406 of the structural member 404 and a second set of electrodes 414 of the flexible circuit assembly 902 are coupled adjacent a second surface 408 of the structural member 404. An adhesive material 428 may be applied to a contact surface (e.g., an inner surface) 910 of the flexible tubular substrate 904 such that when the flexible tubular substrate 904 is compressed, the contact surface 910 of the flexible tubular substrate 904 adheres to the structural member 404. In one embodiment, an opening (e.g., a gap in the space) formed by compressing the flexible tubular substrate 904 may be completely filled with the adhesive material 428.

[0063] Although the splines and spline formation methods of the present invention are described with reference to specific electrode assemblies (such as the basket electrode assembly 200 and the planar electrode assembly 300), it should be understood that the splines and spline formation methods of the present invention are not limited to use in the specific electrode assembly configurations shown and described herein, but can be incorporated into any other suitable electrode assembly such that the functionality of the system 100 ( Figure 1 shown therein) can be as described herein.

[0064] Figure 14 is a perspective view of one of the sub-assemblies 410, 412 arranged to be suitable for the helical configuration 1100 of the system 100 ( Figure 1 shown therein). In the illustrated embodiment, the structural member 404 is omitted. In other embodiments, the individual sub-assemblies 410, 412 can be coupled to a structural member (such as the structural member 404) to facilitate deployment of the individual sub-assemblies 410, 412 into a desired helical shape or other desired shape, such as to facilitate contact with certain anatomical structures. The individual sub-assemblies 410, 412 are wound along the length of the sub-assemblies 410, 412 to form the helical configuration 1100 and are stretched to reduce the outer diameter of the helical configuration 1100. More specifically, in these embodiments, the flexible circuit board 416 of one of the sub-assemblies 410, 412 can be wound into a coil and stretched so as to be inserted into the system 100 as a long linear conduit. In the illustrated embodiment, the electrodes 414 are disposed on the outer surface 418 of the flexible circuit board 416. The electrodes 414 can be any suitable type of electrode, such as unilateral electrodes disposed on the outer surface 418 or electrodes printed on the flexible circuit board 416. In some embodiments, the individual sub-assemblies 410, 412 including the structural member 404 can be wound into a helical configuration.

[0065] Figure 15 To form a spline (such as the spline 400 ( Figure 1 shown therein), the spline 600 ( Figure 5 shown therein) or the spline 900 ( Figure 8 shown therein)) for an electrode assembly (such as the electrode assembly 102 Figure 12Flowchart of an exemplary method 1200 (shown in). Method 1200 includes 1202 providing a structural member (such as structural member 404) that includes a first surface and a second surface. Method 1200 further includes 1204 providing a flexible circuit assembly (such as flexible circuit assembly 402, flexible circuit assembly 602, or flexible circuit assembly 902) that includes a plurality of electrodes and at least one flexible circuit substrate (such as flexible circuit substrate 416 or flexible tubular substrate 904). The at least one flexible circuit substrate has a contact surface and an outer surface opposite the contact surface. The plurality of electrodes are disposed on the outer surface of the at least one flexible circuit substrate. Method 1200 further includes 1206 positioning the flexible circuit assembly relative to the structural member such that a first set of the plurality of electrodes is aligned with the first surface of the structural member and a second set of the plurality of electrodes is aligned with the second surface of the structural member. Method 1200 further includes 1208 coupling the at least one flexible circuit substrate to the at least one structural member and the at least one flexible circuit substrate.

[0066] Although certain steps of the example method are numbered, such numbering does not indicate that these steps must be performed in the order listed. Thus, particular steps need not be performed in the exact order in which they are presented, unless the description specifically requires such an order. These steps may be performed in the order listed or in another suitable order.

[0067] Although the embodiments and examples disclosed herein have been described with reference to specific embodiments, it should be understood that these embodiments and examples are only for illustrative purposes of the principles and applications of the present invention. Thus, it should be understood that various modifications can be made to the illustrative embodiments and examples without departing from the spirit and scope of the present invention as defined by the claims, and other arrangements can be designed. Therefore, this application is intended to cover modifications and variations of these embodiments and their equivalents.

[0068] This written description uses examples to disclose the present invention (including the best mode), and enables any person skilled in the art to practice the present invention (including making and using any device or system, and performing any combined method). The patentable scope of the present invention is defined by the claims, and may include other examples that occur to those skilled in the art. If these other examples have structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims, then these other examples are intended to be within the scope of the claims.

Claims

1. A method of forming a spline for an electrode assembly for a catheter system, the method comprises: providing a structural member including a first surface and a second surface; providing a flexible circuit assembly including a plurality of electrodes and at least one flexible circuit substrate having a contact surface and an outer surface opposite the contact surface, the plurality of electrodes being disposed on the outer surface of the at least one flexible circuit substrate; positioning the flexible circuit assembly relative to the structural member such that a first set of the plurality of electrodes is aligned with the first surface of the structural member and a second set of the plurality of electrodes is aligned with the second surface of the structural member; and coupling the flexible circuit substrates to each other at respective first edges and respective second edges, the coupling forming a gap between at least one flexible circuit substrate and at least one structural member.

2. The method according to claim 1, further comprising coupling the at least one flexible circuit substrate to the structural member using an adhesive.

3. The method according to claim 2, wherein coupling the at least one flexible circuit substrate to the structural member includes coupling the contact surface of the at least one flexible circuit substrate to at least one of the first surface and the second surface of the structural member using an adhesive.

4. The method according to claim 1, further comprising heat-sealing the at least one flexible circuit substrate to at least one of the structural member and the at least one flexible circuit substrate.

5. The method according to claim 1, wherein the at least one flexible circuit substrate includes a first flexible circuit substrate and a separate second flexible circuit substrate, each of the first flexible circuit substrate and the second flexible circuit substrate including respective first longitudinal edges and second longitudinal edges; wherein positioning the flexible circuit assembly relative to the structural member includes positioning the structural member between the first flexible circuit substrate and the second flexible circuit substrate; and wherein coupling the flexible circuit substrates to each other at respective first edges and respective second edges includes coupling the first flexible circuit substrate and the second flexible circuit substrate at respective first longitudinal edges and second longitudinal edges of the first flexible circuit substrate and the second flexible circuit substrate such that a first set of the plurality of electrodes is aligned with the first surface of the structural member and a second set of the plurality of electrodes is aligned with the second surface of the structural member.

6. The method according to claim 5, wherein coupling the first flexible circuit substrate and the second flexible circuit substrate at respective first edges and respective second edges of the first flexible circuit substrate and the second flexible circuit substrate includes coupling the first flexible circuit substrate and the second flexible circuit substrate using an adhesive such that the first flexible circuit substrate and the second flexible circuit substrate are slidable relative to the structural member.

7. The method according to claim 1, wherein the flexible circuit assembly includes a first flexible circuit substrate and a second flexible circuit substrate connected to the first flexible circuit at a fold line, and wherein forming the spline includes folding the first flexible circuit substrate around the fold line and around the structural member relative to the second flexible circuit substrate such that the first set of electrodes is aligned with a first surface of the structural member and the second set of electrodes is aligned with a second surface of the structural member.

8. The method according to claim 7, wherein coupling the flexible circuit substrates to each other at respective first edges and respective second edges includes coupling the first flexible circuit substrate to the second flexible circuit substrate using an adhesive.

9. The method according to claim 1, wherein the structural member is made of nitinol.

10. The method according to claim 1, wherein the at least one flexible circuit substrate is a flexible printed circuit.

11. The method according to claim 1, wherein the structural member includes a plurality of discrete members.

12. The method according to claim 1, further comprising incorporating the formed spline into a planar electrode assembly.

13. The method according to claim 1, further comprising incorporating the formed spline into a basket electrode assembly.

14. An electrode assembly for a catheter system, the electrode assembly having a longitudinal axis, a proximal end, and a distal end, the electrode assembly comprising: at least one spline extending from the proximal end to the distal end of the electrode assembly, the at least one spline including: a structural member extending from the proximal end to the distal end of the electrode assembly, the structural member including a first surface and a second surface; and a flexible circuit assembly including a plurality of electrodes and at least one flexible circuit substrate having a contact surface and an outer surface opposite the contact surface, the plurality of electrodes disposed on the outer surface of the at least one flexible circuit substrate, wherein the flexible circuit assembly is positioned relative to the structural member such that a first set of the plurality of electrodes is aligned with the first surface of the structural member and a second set of the plurality of electrodes is aligned with the second surface of the structural member, and wherein the flexible circuit substrates are coupled to each other at respective first edges and respective second edges and a gap is defined between at least one flexible circuit substrate and at least one structural member.

15. The electrode assembly according to claim 14, wherein the flexible circuit assembly includes a first flexible circuit substrate and a separate second flexible circuit substrate, each of the first flexible circuit substrate and the second flexible circuit substrate including respective first longitudinal edges and second longitudinal edges; wherein the structural member is positioned between the first flexible circuit substrate and the second flexible circuit substrate; and wherein the first flexible circuit substrate and the second flexible circuit substrate are coupled at their respective first longitudinal edges and their respective second longitudinal edges such that a first set of the plurality of electrodes is aligned with the first surface of the structural member and a second set of the plurality of electrodes is aligned with the second surface of the structural member.

16. The electrode assembly according to claim 14, wherein the flexible circuit assembly includes at least two flexible circuit substrates joined at a fold line, and wherein the flexible circuit assembly is folded about the fold line and around the structural member such that the first set of electrodes is aligned with a first surface of the structural member and the second set of electrodes is aligned with a second surface of the structural member.

17. A catheter system, which comprises: a flexible catheter shaft; a handle coupled to a proximal end of the catheter shaft; an electrode assembly coupled to a distal end of the flexible catheter shaft and having a longitudinal axis, a proximal end, and a distal end, the electrode assembly including at least one spline extending from the proximal end to the distal end of the electrode assembly, the at least one spline including: a structural member extending from the proximal end to the distal end of the electrode assembly, the structural member including a first surface and a second surface; and a flexible circuit assembly including a plurality of electrodes and at least one flexible circuit substrate having a contact surface and an outer surface opposite the contact surface, the plurality of electrodes being disposed on the outer surface of the at least one flexible circuit substrate, wherein the flexible circuit assembly is positioned relative to the structural member such that a first set of the plurality of electrodes is aligned with the first surface of the structural member and a second set of the plurality of electrodes is aligned with the second surface of the structural member, and wherein the flexible circuit substrates are joined to each other at respective first edges and respective second edges, and a gap is defined between at least one flexible circuit substrate and at least one structural member.

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