Electrophysiological catheter systems with composite electrodes based on contact force and impedance sensing in irreversible electroporation (IRE) and related methods

Abstract

To provide a catheter system. [Solution] A catheter system for use with a catheter having a distal assembly supporting a plurality of electrodes adapted to sense electrical signals within cardiac tissue and a force sensor configured to generate a first contact signal representing a contact force acting on the distal assembly. The system includes an ablation power generator configured to energize the plurality of electrodes, an impedance circuit configured to generate a second contact signal representing an electrode in contact with tissue, a processor configured to receive the first and second contact signals and generate a switch signal in response thereto, and a switch circuit configured to connect only selected electrodes in contact with tissue to the ablation power generator in response to the switch signal when forming one or more composite electrodes.

Description

Technical Field

[0001] The present invention generally relates to diagnostic catheters and ablation catheters, and more particularly to diagnostic catheters and ablation catheters configured for irreversible electroporation (IRE) of cardiac tissue in unipolar and bipolar modes.

Background Art

[0002] Cardiac arrhythmias such as atrial fibrillation occur when electrical signals abnormally conduct from a region of cardiac tissue to adjacent tissue, thereby disrupting the normal cardiac cycle and causing asynchronous rhythm. The unwanted signal source may be located in atrial or ventricular tissue. The unwanted signal may conduct through cardiac tissue to other locations, causing or sustaining an arrhythmia.

[0003] Procedures for treating arrhythmias include surgically interfering with the source of the signal causing the arrhythmia and interfering with the conduction path of such signals.Cardiac arrhythmias such as atrial fibrillation occur when electrical signals abnormally conduct from a region of cardiac tissue to adjacent tissue, thereby disrupting the normal cardiac cycle and causing asynchronous rhythm. The unwanted signal source may be located in atrial or ventricular tissue. The unwanted signal may conduct through cardiac tissue to other locations, causing or sustaining an arrhythmia. By mapping the electrical properties and cardiac volume of the endocardium and selectively ablating cardiac tissue by applying energy, it may be possible to interrupt or modify the propagation of unwanted electrical signals from one part of the heart to another. The ablation process can disrupt unwanted electrical pathways by forming non-conductive regions of tissue.

[0004] In this two-step procedure, including mapping and subsequent ablation, a first or mapping catheter containing one or more electrical sensors is advanced into the heart, and by acquiring data at a number of points, the electrical activity at each point within the heart can be sensed and measured. Next, using these data, a target area where ablation is to be performed by a second or ablation catheter can be selected.

[0005] During ablation, an RF current is applied to the first electrode of the ablation catheter, and the current flows through the surrounding medium, i.e., blood and tissue, toward a second electrode, which may be another electrode on the catheter or an external skin patch reference electrode. The current distribution is determined by the amount of electrode surface in contact with the tissue compared to blood, which has a higher conductivity than tissue. Heating of the tissue occurs due to its electrical resistance. The tissue is sufficiently heated, causing the destruction of cells within the target tissue and resulting in the formation of non-conductive damage. This damage can form in the tissue in contact with the electrode or in adjacent tissue. During this process, heating of the electrode also occurs as a result of conduction from the heated tissue to the electrode itself.

[0006] The use of multi-electrode catheters for irreversible electroporation (IRE) has been previously proposed in patent literature. For example, International Publication No. 2018 / 191149 describes an electroporation system and method for energizing a catheter to achieve electroporation. The catheter for achieving electroporation includes a distal section and an electrode assembly. The distal section is configured to be positioned within a vein in the body. The vein defines a central axis. The electrode assembly is coupled to the distal section and includes a structure and multiple electrodes distributed around it. The structure is configured to be at least partially in contact with the vein. Each electrode is configured to be selectively energized to form a circumferential ring of energized electrodes concentric with the central axis of the vein. In one embodiment, each electrode is individually wired so that it can be selectively paired or combined with any other electrode to act as a bipolar or multipolar electrode.

[0007] As another example, U.S. Patent No. 8,295,902 describes a tissue electrode assembly comprising a membrane configured to form an expandable and adaptable body that can be deployed in a patient's body. The assembly further comprises a flexible circuit disposed on the surface of the membrane. Conductive electrodes cover at least a portion of the flexible circuit and a portion of the surface of the membrane not covered by the flexible circuit, and the conductive electrodes are foldable together with the membrane to form a delivery configuration having a diameter suitable for minimally invasive delivery of the assembly to the patient. In one embodiment, a pattern of multiple electrodes deposited on the membrane can collectively form a large electrode array of an energy transmission element.

[0008] U.S. Patent Application No. 18 / 159,288, filed on 25 January 2023, entitled "Electrode Designs for Catheters" (hereinafter, "Application 288"), discloses 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 adjacent to the distal end and configured for impedance-based position tracking, and a cover at least partially surrounding the position electrode. The cover may have a plurality of openings, so that a portion of the conductive surface of the position electrode is exposed through each of the multiple openings. The entire contents of Application 288 are incorporated herein by reference and are attached herein by reference as Appendix A.

[0009] The applicants recognize the need to provide a catheter having electrodes configured for both diagnostic mapping and therapeutic ablation, the electrodes being capable of operating in various modalities, including unipolar and bipolar configurations and biphasic voltage pulsation in pulsed field ablation (PFA) to induce irreversible tissue electroporation (IRE), but capable of sensing and ablating the electrical activity of tissue with lower impedance and higher conductivity. [Overview of the project] [Means for solving the problem]

[0010] Embodiments described herein relate to electrophysiological systems using a catheter with an end-effector carrying multiple electrodes configured for both diagnostic mapping and therapeutic ablation, wherein the electrodes can sense the electrical activity of tissue and ablate with high voltage, low impedance, and greater electrical conductivity, and are operable in various modalities including unipolar and bipolar configurations and biphasic voltage pulsation, all of which identify the electrode in contact with tissue via a composite electrode comprising only selected electrodes electrically connected based on contact force sensing and impedance sensing, so that such connected electrodes can withstand the high voltage in pulsed-field ablation (PFA) and induce apoptosis.

[0011] In some embodiments, the catheter system comprises a catheter, an ablation power generator, an impedance circuit, a processor, and a switch circuit. The catheter includes a basket assembly having a plurality of electrodes configured to receive electrical signals from cardiac tissue and a contact force sensor, the contact force sensor configured to generate a first contact signal representing the contact force acting on the basket assembly. The ablation power generator is configured to energize one or more of the plurality of electrodes to deliver energy into cardiac tissue. The impedance circuit is configured to send current to each electrode and generate a second contact signal for each electrode representing contact between the electrode and cardiac tissue. The processor is configured to receive the first and second contact signals to identify the selected electrode in contact with the tissue and to generate a switch signal in response to the first and second contact signals. The switch circuit is configured to electrically connect only the selected electrode to the ablation power generator in response to the switch signal when forming a composite electrode.

[0012] In some embodiments, the switch circuit is configured to electrically connect the electrodes selected for bipolar ablation.

[0013] In some embodiments, the switch circuit is configured to electrically connect the electrodes selected for unipolar ablation.

[0014] In some embodiments, the basket assembly includes a shaft defining a longitudinal axis, a plurality of strips converging at a distal and proximal end, and an elongated pusher extending through the shaft and movable longitudinally relative to the shaft, the elongated pusher having a distal end connected to the distal end of the strips such that movement of the elongated pusher proximal to the shaft along the longitudinal axis bends the strips outward as the basket assembly expands.

[0015] In some embodiments, the catheter includes a position sensor housed within a pusher.

[0016] In some embodiments, the basket assembly folds when the elongated pusher is moved distally along the longitudinal axis relative to the shaft after proximal movement.

[0017] In some embodiments, the contact force sensor is housed within the shaft, proximal to the distal end of the shaft.

[0018] In some embodiments, the contact force sensor includes a first end, a second end, and a deformable spring between those ends.

[0019] In some embodiments, the contact force sensor further includes a magnetic field transmitter housed at a first end and a magnetic field receiver housed at a second end, the magnetic field receiver configured to respond to the magnetic field transmitter by generating a displacement signal indicating a displacement in the spatial relationship between the magnetic field transmitter and the magnetic field sensor.

[0020] In some embodiments, the displacement signal indicates the distance and angular direction of the displacement.

[0021] In some embodiments, each strip includes a flexible polymer circuit strip and an elongated elastic support element.

[0022] In some embodiments, each flexible polymer circuit strip includes a plurality of electrodes aligned along the length of the strip.

[0023] In some embodiments, the ablation power generator is configured to supply ablation energy to the electrodes for pulsed field ablation (PFA) to cause apoptosis in heart tissue.

[0024] In some embodiments, the ablation voltage ranges from about 1 kV to 3 kV. <00OO081>

[0025] In some embodiments, the catheter includes a reference electrode.

[0026] In some embodiments, the reference electrode is circumferentially mounted on the pusher as a ring electrode.

[0027] In some embodiments, the system further includes a user input device configured to instruct the catheter system to operate in a tissue sensing mode or an ablation mode.

[0028] In some embodiments, the user input device includes a manually operable device.

[0029] In some embodiments, the user input device includes a foot-operable device.

[0030] <OO00098>In some embodiments, the switch circuit includes a first switch configured to connect each electrode to an ablation power generator, a second switch configured to connect each electrode to a processing unit, and a third switch configured as a float.

[0031] In some embodiments, the processing unit is configured to activate a switch circuit in response to at least one of a first contact signal and a second contact signal, thereby connecting each electrode to an ablation power generator via a first switch.

[0032] In some embodiments, each electrode is configured as an active electrode.

[0033] In some embodiments, the processing unit is configured to activate a switch circuit in response to at least one of a first contact signal and a second contact signal, thereby connecting each electrode to the processing unit via a second switch.

[0034] In some embodiments, each electrode is configured as a return electrode.

[0035] In some embodiments, the processing unit is configured to activate a switch circuit when there is no contact signal, thereby connecting each electrode to a third switch.

[0036] In some embodiments, the catheter system comprises a catheter, an ablation power generator, a processor, and a switch circuit. The catheter includes a plurality of electrodes and a plurality of force sensors, each force sensor configured to generate a respective contact signal representing the contact force acting on the respective electrode. The ablation power generator is configured to energize the plurality of electrodes. The processor is configured to receive each respective contact signal and, in response, generate a respective switch signal for each electrode. The switch circuit is configured to electrically connect only the selected electrodes in contact with tissue to the ablation power generator in response to each respective switch signal when forming a composite electrode.

[0037] In some embodiments, the system includes a user input device configured to operate an ablation power generator.

[0038] In some embodiments, the processor is configured to operate the ablation power generator in a biphasic mode.

[0039] In some embodiments, the processor is configured to activate a switching circuit between unipolar and bipolar modes.

[0040] In some embodiments, the processing unit is configured to activate a switch circuit between a tissue sensing mode and an ablation mode.

[0041] In some embodiments, the processing unit is configured to activate a switch circuit in response to a control signal from a user input device.

[0042] In some embodiments, the catheter further comprises a reference electrode.

[0043] In some embodiments, the reference electrode is configured to avoid tissue contact.

[0044] In some embodiments, the switch circuit includes a first switch configured to connect each electrode to an ablation power generator, a second switch configured to connect each electrode to a processing unit, and a third switch as a float.

[0045] In some embodiments, the processing unit is configured to activate a switch circuit in response to a contact signal, connecting each electrode to an ablation power generator via a first switch.

[0046] In some embodiments, each electrode is configured as an active electrode.

[0047] In some embodiments, the processing unit is configured to activate a switch circuit in response to a contact signal, thereby connecting each electrode to the processing unit via a second switch.

[0048] In some embodiments, each electrode is configured as a return electrode.

[0049] In some embodiments, the processing unit is configured to activate a switch circuit when there is no contact signal, thereby connecting each electrode to a third switch.

[0050] In some embodiments, the catheter includes an expandable distal assembly with spines, on which electrodes are positioned.

[0051] In some embodiments, the distal assembly is configured as a 3D form having an interior, and the reference electrode is placed inside the distal assembly.

[0052] In some embodiments, the catheter includes a shaft, the distal assembly extends from the distal end of the shaft, and the distal assembly includes a strut extending from the distal end of the shaft to the electrode, the strut being configured to deform in response to a contact force acting on the electrode.

[0053] In some embodiments, a force sensor is attached to a support column and configured to generate a contact signal in response to deformation of the support column. [Brief explanation of the drawing]

[0054] These features and advantages of the present invention, as well as other features and advantages, will be better understood by considering the following detailed description in conjunction with the accompanying drawings. Please note that in certain drawings, certain selected structures and mechanisms are not shown in order to make the remaining structures and mechanisms easier to see. [Figure 1] This is a diagram of an electrophysiological system according to one embodiment of the present invention, for sensing electrical activity in cardiac tissue and performing ablation on cardiac tissue. [Figure 2A] This is a perspective view of a catheter for use with the system shown in Figure 1, according to one embodiment of the present invention. [Figure 2B] This is a side view of the contact force sensor shown in Figure 2A, according to one embodiment of the present invention. [Figure 3] Figure 2A is a perspective view of the distal electrode assembly according to one embodiment of the present invention. [Figure 4A] This is a side cross-sectional view of the distal portion of the distal electrode assembly shown in Figure 3, according to one embodiment of the present invention. [Figure 4B] This is a side cross-sectional view of the proximal portion of the distal electrode assembly shown in Figure 3, according to one embodiment of the present invention. [Figure 5A] Figure 3 is a schematic diagram of the distal electrode assembly in both its extended and folded forms, according to one embodiment of the present invention. [Figure 5B] Figure 3 is a schematic diagram of the distal electrode assembly in both its extended and folded forms, according to one embodiment of the present invention. [Figure 6] This is a block diagram of the system shown in Figure 1, relating to one embodiment of the present invention. [Figure 7] This flowchart shows a method 300 for diagnosing and treating cardiac arrhythmias according to one embodiment of the present invention. [Figure 8] This is a perspective view of an extended distal electrode assembly according to another embodiment of the present invention. [Figure 9] This is a perspective view of an extended distal electrode assembly according to yet another embodiment of the present invention. [Figure 10] This is a block diagram of the system configured for use with the distal electrode assembly shown in Figure 9. [Figure 11] This is a block diagram of the system shown in Figure 10 in tissue sensing mode, according to one embodiment of the present invention. [Figure 12] This is a block diagram of the system shown in Figure 10 in unipolar ablation mode, according to one embodiment of the present invention. [Figure 13] This is a block diagram of the system shown in Figure 10 in bipolar ablation mode, according to one embodiment of the present invention. [Modes for carrying out the invention]

[0055] The following detailed description should be read in reference to the drawings, where similar elements in different drawings are numbered identically. The drawings are not necessarily to scale, depict selected embodiments, and are not intended to limit the scope of the invention. The detailed description is illustrative of the principles of the invention, not limiting, but illustrating them as examples. This specification describes several embodiments, adaptations, modifications, alternatives, and uses of the invention, including those that are currently considered to be the best modes for carrying out the invention, which will make it obvious to those skilled in the art how to make and use the invention.

[0056] As used herein, the terms “about” or “approximately” for any number or range indicate a preferred dimensional tolerance that enables some or all of the components to function for the intended purposes described herein. More specifically, “about” or “approximately” may refer to a range of values ​​within ±10% of the enumerated values; for example, “about 90%” may refer to a range of values ​​between 81% and 99%.

[0057] In addition, as used herein, the terms “patient,” “host,” “user,” and “subject” refer to any human or animal subject, and while the use of the present invention in a human patient represents a preferred embodiment, it is not intended to limit the system or method to human use. Furthermore, the term “proximal” refers to a location closer to the operator, while “distal” refers to a location further away from the operator or physician.

[0058] Any one or more of the teachings, expressions, modifications, examples, etc., described herein may be combined with any one or more of the other teachings, expressions, modifications, examples, etc., described herein. Therefore, the teachings, expressions, modifications, examples, etc., described below should not be considered in isolation. In light of the teachings herein, various preferred ways in which they may be combined will be readily apparent to those skilled in the art. Such modifications and variations are intended to be included within the scope of the claims.

[0059] Exemplary end effectors, which are substantially planar and include a plurality of electrodes that can be configured for mapping and / or ablation, are illustrated and disclosed herein. The end effectors can be joined to a shaft having additional catheter components to form a mapping and / or ablation catheter through processes disclosed herein and processes similar to those known to those skilled in the art. The exemplary end effectors illustrated herein include modifications and features that can be combined to form additional end effector designs, as will be understood by those skilled in the art.

[0060] The following detailed description should be read in reference to the drawings, where similar elements in different drawings are numbered identically. The drawings are not necessarily to scale, depict selected embodiments, and are not intended to limit the scope of the invention. The detailed description is illustrative of the principles of the invention, not limiting, but illustrating them as examples. This specification describes several embodiments, adaptations, modifications, alternatives, and uses of the invention, including those that are currently considered to be the best modes for carrying out the invention, which will make it obvious to those skilled in the art how to make and use the invention.

[0061] Where used herein, the terms “about” or “approximately” for any number or range indicate a preferred dimensional tolerance that enables some or all of the components to function for the intended purposes described herein. More specifically, “about” or “approximately” may refer to a range of values ​​within ±20% of the enumerated values. For example, “about 90%” may refer to a range of values ​​between 71% and 110%. In addition, where used herein, the terms “patient,” “host,” “user,” and “subject” refer to any human or animal subject, and while the use of the present invention in a human patient represents a preferred embodiment, it is not intended to limit the system or method to human use. Furthermore, the term “proximal” refers to a location closer to the operator or physician, while “distal” refers to a location further away from the operator or physician.

[0062] As discussed herein, the vascular systems of “patient,” “host,” “user,” and “subject” can be human or any animal vascular system. It should be understood that animals can be any applicable type, including but not limited to mammals, veterinary animals, domestic animals, or pet animals. For example, an animal could be a laboratory animal specifically selected to have certain characteristics similar to humans (e.g., rats, dogs, pigs, monkeys, etc.). It should be understood that a subject could be, for example, any applicable human patient.

[0063] As discussed herein, “operator” may include physicians, doctors, surgeons, technicians, scientists, or any other individuals or delivery devices associated with the delivery of a multi-electrode catheter for the treatment of drug-refractory atrial fibrillation to a subject.

[0064] As discussed herein, the terms “to ablate” or “ablation,” in the context of the devices and corresponding systems of this disclosure, refer throughout this disclosure to components and structural features configured to reduce or prevent the generation of irregular cardiac signals within cells by utilizing non-thermal energy, such as irreversible electroporation (IRE), which is interchangeably referred to as pulsed electric field (PEF) and pulsed-field ablation (PFA). In the context of the devices and corresponding systems of this disclosure, “to ablate” or “ablation” is used throughout this disclosure to refer to non-thermal ablation of cardiac tissue in a particular condition, including but not limited to arrhythmias, atrial flutter ablation, pulmonary vein isolation, supraventricular tachycardia ablation, and ventricular tachycardia ablation. The terms “to ablate” or “ablation” also include known methods, devices, and systems for achieving various forms of body tissue ablation, as will be understood by those skilled in the art.

[0065] As discussed herein, when the terms “bipolar” and “monopole” are used to refer to ablation schemes, they describe different ablation schemes with respect to the current path and electric field distribution. “Bipole” refers to an ablation scheme that utilizes a current path between two electrodes, both placed at the treatment site. The current density and magnetic flux density are typically approximately equal in each of the two electrodes. “Monopole” refers to an ablation scheme that utilizes a current path between two electrodes, where one electrode with a high current density and high electric flux density is placed at the treatment site, and a second electrode with a relatively low current density and lower electric flux density is placed at a distance from the treatment site.

[0066] As discussed herein, the term “biphasic pulse” refers to an electrical signal having a positive voltage phase pulse (referred to herein as “positive phase”) and a negative voltage phase pulse (referred to herein as “negative phase”). A “single-phase pulse” refers to an electrical signal having only a positive phase or only a negative phase. A system providing a biphasic pulse is configured to prevent the application of direct current (DC) voltage to a patient. For example, the average voltage of a biphasic pulse may be zero volts relative to ground or other common reference voltage. Additionally or alternatively, the system may include capacitors or other protective components. Where the voltage amplitude of a biphasic pulse is described herein, it is understood that the expressed voltage amplitude is the absolute value of the approximately peak amplitude of each of the positive voltage phase or negative voltage phase. Each phase of a biphasic pulse preferably has a square shape with an essentially constant voltage amplitude over most of the phase duration. The phases of a biphasic pulse are temporally separated by an interphase delay. The interphase delay duration is preferably less than or approximately equal to the duration of the phase of the biphasic pulse. The interphase delay duration is preferably about 25% of the phase duration of the biphasic pulse.

[0067] As discussed herein, the terms “tubular” and “tube” are to be interpreted broadly and are not limited to a right cylindrical structure, a structure with a strictly circular cross-section, or a structure with a uniform cross-section over its entire length. For example, a tubular structure is generally illustrated as a substantially right cylindrical structure. However, a tubular structure may have a tapered or curved outer surface without departing from the scope of this disclosure.

[0068] In electrophysiological systems, electrical activity within the heart is detected using a catheter with two or more electrodes for bipolar mapping. Electrical activity within the heart is detected using a first electrode configured to sense both local activation energy (proximity signal) at the point of contact with cardiac tissue and far-field activation energy (remote signal) received by the electrode through the blood. A second electrode, located adjacent to the first electrode, is configured to receive approximately the same far-field signal but not the local activation energy (proximity signal). A suitable signal processing unit can process the signals received by both the first and second electrodes and more accurately determine the proximity signal by subtracting the remote signal detected by the second electrode from the proximity and remote signals detected by the first electrode.

[0069] The catheter typically also includes a position sensor, such as an electromagnetic position sensor. Suitable electromagnetic sensors are described in U.S. Patents No. 5,443,489, 5,480,422, 5,546,951, 5,568,809 and 5,391,199, the disclosures of which are incorporated herein by reference. In some embodiments, to use the electromagnetic sensor, the patient is placed in a generated magnetic field, for example, by placing a pad containing a coil for generating a magnetic field below the patient. A reference electromagnetic sensor is fixed to the patient, for example, taped to the patient's back, and the catheter with the electromagnetic position sensor is advanced into the patient's heart. Each sensor preferably comprises three small coils that generate an electrical signal indicating their position in the magnetic field. The signals generated by both the fixed reference sensor and the sensors in the catheter in the heart are processed to confirm the precise location of the sensors in the catheter relative to the reference sensor. Using this technique, a physician can visually map the cardiac chambers. This mapping is performed by advancing the catheter into the cardiac chambers until its distal tip makes contact with the heart wall. This position is recorded and saved. The distal tip is then moved to another position where it makes contact with the heart wall, and this position is saved again. By combining electromagnetic sensors and sensing electrodes, physicians can generate a 3D electroanatomical map to simultaneously map the contours or shapes of the cardiac chambers and the electrical activity of the heart, and display it on a monitor. Thus, physicians may observe and diagnose abnormal electrical activity in a patient's heart.

[0070] 3D electroanatomical maps can also be based on estimated anatomical maps. In the field, mapping algorithms based on such measurements, such as fast anatomical mapping (FAM), are known. The FAM method can provide physicians with further mapping capabilities, such as electrophysiological (EP) mapping, which can be used for cardiac ablation. During the FAM process, the physician guides the distal end of a catheter to the desired position and collects anatomical signals from there. In principle, FAM can provide the physician with a surface representing the estimated anatomical mapping of the tissue in question. Point locations on the surface of the cardiac chambers are plotted using the acquired electroanatomical data. This surface is used by the physician during EP mapping and ablation procedures.

[0071] The catheter may also be configured to provide hybrid magnetic-based and impedance-based position sensing, benefiting from both the high accuracy of magnetic position sensing and the lower cost of impedance-based sensing. In impedance-based active current location (ACL) sensing, impedance is measured between an electrode on the catheter and an external skin patch electrode placed on the patient's body. An electrical signal is applied to the electrode on the catheter ("active" electrode), and the resulting voltage and / or current is measured at the external skin patch electrode ("return" electrode). In hybrid position sensing, an externally applied magnetic field is measured by a magnetic field sensor to derive the precise position coordinates of the catheter. A current or voltage from the external skin patch electrode is also applied, and the impedance between the external skin patch electrode and the catheter electrode is measured. Dual position measurements are repeated at multiple locations within the body cavity to generate a calibration map, correlating the impedance measurements with the position coordinates confirmed by the magnetic field sensor. Additional catheters with diagnostic or therapeutic functions may be introduced into the heart, and the impedance measurements taken from the electrodes of these additional catheters are correlated with a calibration map to determine the precise position coordinates of these additional catheters; therefore, these additional catheters do not need to include magnetic field sensors. In particular, the typical values ​​of the frequency and amplitude of the active-current-location (ACL) signal are approximately 100 kilohertz (kHz) and 1 millivolt (mV), respectively, while the values ​​of the frequency and amplitude of the ECG signal are approximately 1 hertz (Hz) and 1 microvolt (μV), respectively.

[0072] An ablation system typically comprises a catheter having at least two electrodes coupled to an energy source. One electrode is configured as an anode and the other as a cathode. The electrodes are energized with a DC voltage and may conduct current at various frequencies, amplitudes, pulse widths, and polarities. When the energy source supplies an energizing potential to the electrodes, the current is conducted through the patient tissue between the first and second electrodes. The polarity of the electrodes may be reversed by reversing the polarity of the output of the energy source. The current supplied by the energy source may consist of pulses or pulse sequences. Each pulse may be biphasic, consisting of a first component having polarity and a second component having the opposite polarity. The pulses may consist of unipolar / bipolar mixed pulses.

[0073] Irreversible electroporation, also known as pulsed-field ablation, can be used as an invasive therapeutic method to kill tissue cells by exposing them to high-voltage pulses. Specifically, IRE pulses have potential applications in killing myocardial tissue cells to treat cardiac arrhythmias. Cell destruction occurs when the transmembrane potential difference exceeds a threshold, leading to cell death and subsequent tissue damage. Therefore, of particular interest is the use of high-voltage bipolar electrical pulses, for example, using a selected pair of electrodes in contact with the tissue to generate a high electric field exceeding a specific threshold to kill tissue cells between the electrodes.

[0074] Embodiments of the present invention described below utilize a multi-electrode catheter configured for both mapping and ablation, including RF, PFA, and IRE ablation with IRE pulses of typical magnitude 1kV to 3kV, capable of operating in both unipolar and bipolar modes. The catheter may include a balloon, basket, or lasso having coated electrodes adapted to reduce impedance and increase conductivity in order to improve current delivery for ablation. Furthermore, the catheter allows for selective electrical connection or "short-circuiting" of multiple electrodes, for example, electrodes on selected spines, based on the detection of tissue contact at each electrode, in order to minimize the application of excessive current to the patient by ablating only at the electrodes as needed. These selective "short-circuiting" of electrodes effectively form a single composite catheter electrode for more efficient ablation.

[0075] Figure 1 is a schematic diagram of a catheter-based irreversible electroporation (IRE) system 10 using a basket catheter 27, the shaft 129 of the catheter 27 being inserted by a physician 24 through the patient's vascular system 23. The catheter is configured so that the physician can navigate the end effector or expandable basket electrode assembly 127 of the catheter 27 to a target location within the patient's heart 12.

[0076] In the embodiments shown in Figures 2A and 3, the shaft 129 of the basket catheter 27 includes a deflectable section 112, and the basket catheter 27 includes an elongated pusher 118 that extends through the shaft 129 and the deflectable section 112 and is longitudinally movable thereto. The pusher 118 has a distal section 120 that acts on the distal end of the basket assembly 127, so that a physician 24 can use, for example, a manipulator or handle (not shown) to pull the pusher 118 against the shaft 129 to expand the basket assembly 127 as shown in Figure 5A, or extend the pusher 118 to fold the basket assembly as shown in Figure 5B. The basket assembly 127 includes a plurality of flexible polymer circuit strips 124. Each flexible polymer strip 124 includes a plurality of electrodes 26 positioned thereon. Referring to Figures 4A and 4B, the basket catheter 27 includes a nose connector 130 that connects to the distal portion 120 of the pusher 118. The flexible polymer circuit strip 124 is connected to the nose connector 130 via a hinge 128 formed at the distal end 146 of the flexible polymer circuit strip 124. The distal end 146 is sandwiched between the nose cap 132 and the nose connector 130, and therefore does not have an electrode 26. The basket catheter 27 also includes each elongated elastic support element 148 positioned along a given length of each strip of the flexible polymer circuit strip 124, giving the basket assembly 127 its shape in an expanded form.

[0077] As shown in Figures 5A and 5B, the flexible polymer circuit strip 124 is configured to bend radially outward when pulled in by the physician as the pusher 118 expands the basket assembly 127 from its folded state, and to extend substantially parallel to the pusher 118 when advanced by the physician as the pusher 118 folds the basket assembly from its expanded state. The folded state of the expandable assembly 127 represents the stress-free form of the flexible polymer circuit strip 24, whose shape is given by the elongated elastic support element 148.

[0078] In some embodiments, the distal portion 120 of the pusher 118 houses a multi-axis position sensor 14 (Figure 4A), which may include a biaxial or triaxial position sensor, such as a magnetic position sensor with multiple orthogonal coils. Wiring 176 for transmitting position signals is connected to the multi-axis position sensor 14 via the hollow portion of the pusher 118. The nose cap 132 covers the nose connector 130 attached to the distal portion 120 of the pusher 118, thereby holding the multi-axis position sensor 14 to the nose connector 130, while also securing the distal end 146 of the strip 124 to the nose connector 130 and thus to the distal portion 120 of the pusher 118. An irrigation sleeve 172 (Figure 4B) is positioned within the shaft 129, in which case the distal end of the irrigation sleeve is generally coplanar with the distal end 131 of the shaft 129 so that the irrigation fluid can pass through the shaft and exit from the distal end of the shaft. A uniaxial position sensor 186 is positioned circumferentially around the irrigation sleeve 172, immediately proximal to the distal end 131. The uniaxial position sensor 186 allows the navigation system to locate the distal end of the catheter. Similar basket catheters are described in U.S. Patent Application Publication 2021 / 0187241 and U.S. Patent Application Publication 2023 / 0346459, whose entire disclosure is incorporated herein by reference.

[0079] After the basket assembly 127 reaches the target position as shown in Figure 1, the physician pulls in the pusher 118 to expand the basket assembly 127. The physician 24 then manipulates the shaft 129, which includes a deflectable section 112, to deflect the basket assembly in one direction or in both directions, thereby causing one or more electrodes 26 positioned on the basket assembly 127 to come into contact with the tissue of the heart 12 to sense electrical activity, including intracardiac electromagnetism (IEGM) signals, to map the ventricles of the heart 12, and / or apply voltage through the electrodes 26, including high-voltage PFA pulses for irreversible electroperforation (IRE).

[0080] Referring to Figure 6, the system 10 includes a patient interface unit (PIU) 30, an ablation power generator 34, and an operating console 31 which may include a display 36 for displaying a 3D map and electrophoresis. The ablation power generator 34 is adapted to conduct ablation energy to the ablation electrode. The energy generated by the ablation energy generator may include, but is not limited to, radio frequency (RF) energy or pulsed-field ablation (PFA) energy, or a combination thereof, including unipolar or bipolar high-voltage DC pulses, which may be used to induce irreversible electroperforation (IRE). The PIU 30 is an interface configured to establish electrical communication between the catheter, electrophysiological equipment, power supply, and a system controller for controlling the operation of the system 10. In some embodiments, the PIU 30 further includes processing capabilities for performing real-time calculations of the catheter position and performing ECG calculations.

[0081] The operation, functions, and behavior of system 10 are managed by a system controller 11, which includes a processing unit 41 that communicates with memory 42 containing software for the operation of the system. In some embodiments, at least some of the operation, functions, or behavior of the system controller 11 is performed using custom-designed hardware and software, such as an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA). In some embodiments, the system controller 11 is managed by a physician using a user interface device that allows the physician to set system parameters. The results of the procedure are provided to the physician on a display 36. The software in memory 42 may be downloaded to the system controller 11 in electronic form, for example, via a network. Alternatively or additionally, the software may be provided on a non-temporary tangible medium, such as an optical, magnetic, or electronic storage medium.

[0082] As shown in Figure 6, in some embodiments, the memory 42 includes a number of modules used by the processing unit 41, for example, a system module 60 for controlling the modules in the memory 42 and the processing unit 41 when the modules are executed, an irrigation module 61 for controlling the supply and flow of fluid through the catheter, a temperature sensing module 62 for sensing temperature at a tissue target location, a sensing tissue signal module 63 for sensing cardiac electrical signals such as IEGM signals for generating an electrophoresis diagram, and a position sensing module 64 for tracking the position (location and orientation) of the distal end 22 of the catheter, the position sensing module may include a magnetic-based position sensing subroutine 65 that responds to an external magnetic field, or an impedance-based ACL subroutine 66 for position sensing based on a hybrid of electromagnetic position sensing and impedance-based active current position (ACL) sensing. Memory 42 may also include a 3D EA mapping module 67 for generating a 3D electroanatomical map of the heart showing the electrical activity of the heart and the location of such activity; a force sensing module 68 for sensing contact between the distal end 22 of the catheter and cardiac tissue 12; and an ablation (PFA) module 69 including a biphasic subroutine 71 for controlling and applying ablation, including PFA, to cardiac tissue. Memory 42 may further include a switch control module 73 having a tissue sensing subroutine 74 for controlling switch connections in the electrode electrical circuit for sensing tissue electrical signals, and a unipolar subroutine 75 and a bipolar subroutine 76 for controlling switch connections in the electrode electrical circuit as “active” or “return” electrodes during ablation. In some embodiments, memory 42 also includes a patient data storage device 77 for storing data received and / or generated by the system.

[0083] In some embodiments, the system controller 11 includes an industrial-standard personal computer 43, which includes a general-purpose computer processing unit that responds to user input devices 44, including, for example, a mouse 45, a keyboard 46, a touchscreen 47, and / or a foot pedal 99. Additional user input devices may include an ablation polarity toggle controller 48 for switching between unipolar ablation mode and bipolar ablation mode, and a toggle controller 50 for switching between tissue electrical sensing mode and ablation mode.

[0084] In some embodiments, the PIU 30 of the system controller 11 includes a circuit connection device, which includes a switch circuit 51 with switches and / or relays that respond to controllers 48, 50 of the user input device 44 when electrically connecting / disconnecting the selected catheter electrode 26 to the ablation power generator 34 or the processing unit 41, for example, when the electrode 26 functions as an "activate" or "return" in an electrical circuit used for user-selected operating modes between tissue electrical activity sensing, unipolar ablation, and bipolar ablation. As shown in the embodiment of Figure 6, each electrode E1 to EN+1 is coupled to the switch circuit 51 via its respective leads L1 to LN+1, further coupled to the ablation power generator 34 via its respective lead M (collectively referred to as M / N+1), and coupled to the processing unit 41 via its respective lead J (collectively referred to as J / N+1). The reference electrode Eref is also connected to the switch circuit 51 by lead 52, and further connected to the processing unit 41 by lead 53. As shown in Figure 4A, the central ring electrode 140 is attached to the outer surface of the proximal portion of the nose connector 130. Surrounded by the strip 124, the central ring electrode 140 is generally isolated from tissue contact and can therefore function as a reference electrode as needed or appropriately.

[0085] Selected electrical connections / disconnections of the electrodes 26 to the ablation power generator 34 and / or processing unit 41 via the switch circuit 51 are adjusted based on the detection of contact between the electrodes 26 and cardiac tissue 12, and / or the degree to which such contact exceeds a predetermined threshold force, by a contact force sensor assembly 220 coupled to the processing unit 41 and configured to detect contact between tissue and a basket assembly, including contact between one or more electrodes and cardiac tissue.

[0086] The basket catheter 27 is configured for multiple functions, including sensing tissue electrical signals and tissue ablation. As shown in Figure 1, the physician places the basket assembly 127 of the catheter 27 into contact with the heart wall to sense a target site within the heart 12. For ablation, the physician 24 similarly places the basket assembly 27 into contact with the heart wall at the target site. To track the position of the basket assembly 27, the catheter includes a multi-axis position sensor 14 housed in a nose connector 130 at the distal end of the pusher 118 (Figures 3 and 4A). In some embodiments, the position sensor 14 is a magnetic-based position sensor having three magnetic coils for sensing three-dimensional (3D) position and orientation. The magnetic-based position can be operated in conjunction with a position pad 25 containing multiple magnetic coils 32 configured to generate a magnetic field within a given working volume. The real-time position of the basket assembly 127 can be tracked based on the magnetic field generated by the position pad 25 and sensed by the magnetic-based position sensor 14. Details of magnetic-based position sensing technology are described in U.S. Patents No. 5,5391,199, No. 5,443,489, No. 5,558,091, No. 6,172,499, No. 6,239,724, No. 6,332,089, No. 6,484,118, No. 6,618,612, No. 6,690,963, No. 6,788,967, and No. 6,892,091.

[0087] System 10 includes one or more electrode patches 38 placed on a patient 23 for skin contact to establish a position reference at the position pad 25, as well as impedance-based position tracking of the electrodes 26. For impedance-based position tracking, the system controller 11 activates a driver circuit 80 to send current to each electrode 26, which is sensed at each electrode skin patch 38 and used to measure the impedance between the electrode 26 and the electrode skin patch 38. Based on the measured impedance, the processing unit 41 can access the impedance-based ACL subroutine 66 of the position module 64 to determine the position of the basket assembly 127 relative to the electrode skin patches 38. Details of the impedance-based position tracking technique are described in U.S. Patents 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182.

[0088] As shown in Figure 2A, the contact force sensor assembly 220 is located in the shaft 129 proximal to the basket assembly 127. In the illustrated embodiment of Figure 2B, the force contact sensor assembly 220 includes a proximal end 222 and a distal end 224, the proximal end 222 housing a magnetic field transmitting coil 232 and the distal end 224 housing a magnetic field receiver 232. As understood in the art, the magnetic field transmitting coil 232 may be configured to generate a magnetic field, and the magnetic field receiving coil 231 may be configured to detect the presence and magnitude of a magnetic field. The contact force sensor assembly 220 may further include an elastically deformable deflection section 226 located between the proximal end 222 and the distal end 224 and configured to deflect when a force is applied to the contact force sensor assembly 220. The deflection section 226 may be configured to allow the spatial relationship between the proximal end 222 and the distal end 224 to change when a force is applied. In the illustrated embodiment, the deflection portion 226 includes a helical spring 226, in which case the distal edge 260 of the tube 240 includes an opening 262 (partially labeled for simplification) arranged around the outer circumference of the distal edge 260. The inner proximal surface 258 of the distal coupler 226 includes a projection 264 (partially labeled for simplification) arranged circumferentially around the inner proximal surface 258 and configured to engage with the opening 262 (or a slot arranged around the outer circumference of the substantially tubular member 38) to prevent rotation of the distal coupler 226 relative to the tube 240. The opening 262 and the projection 264 may be of any preferred shape. In some embodiments, the opening 262 includes a U-shaped opening as shown in Figure 2B.

[0089] As a result of the change in spatial relationship when the deflection section 226 is deformed due to the application of a contact force to the basket assembly 127, the magnetic field receiving coil 231 will detect a change in the magnetic field (caused by the movement of the sensor 232). Since the spring constant K of the deflection section 226 can be predetermined and the distance between the magnetic field transmitting coil 232 and the magnetic field receiving coil 231 can be detected, the force applied to the basket assembly 127 can be determined. Furthermore, if the magnetic field receiving coil 231 includes at least three magnetic sensing coils, the angular direction and magnitude of the displacement between the magnetic field transmitting coil 232 and at least three magnetic sensing coils 2315 can be determined by triangulation. A suitable contact force sensor is described in U.S. Patent Application Publication 2023 / 0346459, the entire disclosure of which is incorporated herein by reference. Since the configuration of the basket assembly 127 and the arrangement of the flexible polymer circuit strip 124 and the electrodes 26 thereon are known, the spatial relationship of each electrode 26 on the basket assembly 127 to the contact force sensor assembly 220 can also be predetermined. Therefore, the identity of the electrode 26 on the basket assembly 127 that is in tissue contact can be inferred when the contact force sensor assembly 220 detects the directional and distance displacement of the proximal end 222 relative to the distal end 224.

[0090] The inference of contact between any particular electrode 26 and tissue by the contact force sensor 220 can be confirmed by impedance measurement. As stated, impedance can be measured between the electrode 26 and the electrode skin patch 38, as shown in Figure 1. In addition to the system 10 determining catheter position by using impedance measurements between the electrode 26 and the patch 38, the system controller 11 can also infer tissue contact via the driver circuit 80 to bring current between each electrode 26 and the corresponding body surface electrode 38 and measure the impedance between them when determining whether each electrode is in contact with tissue. Since impedance increases when an electrode in contact with blood moves and makes contact with tissue, it is understood that the system 10 can at least infer, if it does not determine, which electrode 26 on the basket assembly 127 is in contact with tissue, by using impedance measurements in combination with the detection of displacement by the contact force (and force direction) sensor assembly 220. In other embodiments, the body surface electrode 38 may take other forms, such as a subcutaneous probe or a handheld device operated by a medical professional.

[0091] Figure 7 is a flowchart of a method 300 for diagnosing and treating cardiac arrhythmias according to one embodiment of the present invention. In block 302, the method 300 includes positioning a catheter 27 together with a basket assembly 127 in a location within the heart. The physician 24 can use a deflection section 112 to deflect the catheter 27 when manipulating the basket assembly 127 to a predetermined location within the heart.

[0092] In block 204, the method includes determining whether the basket assembly 127 is in contact with the heart tissue via the contact force sensor 220 (block 304). In some embodiments, referring to Figure 6, the processing unit 41 accesses the force sensing module 68 to activate the contact force sensor 220. When the deformable portion 226 of the sensor 220 bends or otherwise deforms in response to an external force exerted on the basket assembly 127 by the heart tissue, the sensor 220 generates a signal indicating contact between the basket assembly 127 and the heart tissue.

[0093] In block 306, the physician operates the catheter 27 in diagnostic tissue sensing mode via the switch 50 for the electrode 26 to sense the electrical activity of the heart. In some embodiments, the processing unit 41 accesses the tissue sensing subroutine 74 of the switch control module 73 to activate the switch circuit 51 for proper switch connections between the electrodes E1~EN+1 and the processing unit 41, and the processing unit 41 also receives the sensed electrical activity of the heart for measuring the ECG.

[0094] In block 308, the processing unit 41 accesses the 3D EA mapping module 67 to create a 3D electroanatomical map for display on the display 36. The processing unit 41 accesses memory or storage loaded with appropriate operating software, and user interface functions may include modeling the endocardial anatomical structure in three dimensions (3D) and rendering the model or anatomical map 20 for display on the display device 36. Other functions may include displaying representative visual indicators or activation sequences (or other data) edited from electrographs recorded in images overlaid on the rendered anatomical map, displaying the real-time position and orientation of the catheter in the cardiac chambers, and displaying sites of interest such as the location where ablation energy was applied. One commercially available product embodying the elements of system 10 is available as the CARTO® 3 system, commercially available from Biosense Webster, Inc. (31 Technology Drive, Suite 200, Irvine, CA 92618, USA).

[0095] In some embodiments, the processing unit 41 uses the sensed cardiac electrical activity and a 3D mapping of the heart via a magnetic-based position sensing subroutine 65 of a position sensing module 64 and a multi-axis position sensor 14 housed in a nose connector 130 inside the basket assembly 127. An impedance-based ACL subroutine 66 may also be used to determine the position of the basket assembly 127. The 3D electroanatomical map should reveal areas of irregular electrical signals within the heart, such as arrhythmias.

[0096] In block 310, the physician operates the catheter in therapeutic mode via a switch controller 50 at electrodes E1 to EN+1 to receive ablation energy and ablate the cardiac tissue in contact with the electrodes. The controller 50 is a toggle that switches between tissue sensing (e.g., mapping) mode and ablation mode, and may be, for example, a manual control switch or a foot pedal. In some embodiments, the processing unit 41 accesses the ablation module 69 and operates the switch circuit 51 for appropriate switch connections between the electrodes and the ablation power generator 34 for the delivery of ablation energy. In this regard, ablation energy is delivered only to electrodes in contact with cardiac tissue as determined by the contact force sensor 220 assembly. Furthermore, if the displacement between the proximal end 222 and distal end 224 of the contact force sensor assembly 220 is defined and measured in terms of distance and angular direction by the magnetic field receiving coil 231 in response to the magnetic field transmitter 231, the processing unit 41 can infer which electrode is in contact with cardiac tissue using the configuration of the basket assembly 127 and the positions of each electrode E1 to EN+1 within that configuration using a force sensing module 68. In some embodiments, this inference can be confirmed by impedance measurement, with the understanding that impedance increases when an electrode is in contact with cardiac tissue and decreases when an electrode is not in contact with cardiac tissue. For example, impedance measurements can be obtained by the processing unit 41 when accessing the impedance-based ACL subroutine 66 of the position sensing module 64 to activate a switch circuit 51 for an electrical connection between each electrode 26 and the processing unit 41, and the processing unit 41 then sends the current received by the processing unit 41 to each electrode 26 when measuring the impedance of each electrode.By combining displacement measurements from the contact force sensor assembly 220 with tissue contact via impedance measurements of each electrode, the processing unit 41 can identify which electrodes are in contact with cardiac tissue (as well as the approximate contact force and direction of the force applied to the electrodes) when forming one or more composite electrodes for delivering PFA to selected areas within the heart, and accordingly activate the switch circuit 51 to disconnect the electrical connection from the ablation power generator 34 to electrodes not in contact with cardiac tissue, and connect only the electrodes in contact with cardiac tissue to the ablation power generator 34. For example, referring to Figure 3, the processing unit 41 identifies electrodes A, B, C, and D that come into contact with cardiac tissue and activates the switch circuit 51 to connect electrodes A and B when forming a first composite electrode and electrodes C and D when forming a second composite electrode, wherein the first composite electrode is the active electrode and the second composite electrode is the return electrode for bipolar ablation, or both the first and second composite electrodes are active electrodes and a third electrode, such as the central ring electrode 140 or the body surface patch 38, is the return electrode for unipolar ablation. Selective electrical connection of electrodes allows for the delivery of higher voltage ablation energy in PFA and IRE by combining smaller electrodes without damaging the basket assembly or exposing the patient to excessive ablation energy.

[0097] Figures 8 and 9 show a catheter 327 in which the basket assembly 328 is in an expanded state when not constrained, such as by advancing from the distal end 381 of the sheath 380. The basket assembly 328 includes a number of flexible spines 321 that extend beyond the end of the shaft 329. In the illustrated embodiment, the spines 321 converge at both the distal and proximal ends of the basket assembly 328. During a medical procedure, the physician can unfold the basket assembly 328 by advancing the shaft 329 distally relative to the sheath 380 and withdrawing the basket assembly 328 from the sheath 380, thereby transitioning it from a folded state to an expanded state. In the expanded state, the spines 321 of the basket assembly 328 are bent radially outward along the longitudinal axis 386, while in the folded state, the spines 321 are constrained substantially along the longitudinal axis 386 of the shaft 329 of the catheter 327.

[0098] Referring to Figures 8 and 9, each of electrodes E1 to E10 may be coated with an impedance-reducing coating as described in detail in U.S. Patent Application No. 18 / 159,288, which is incorporated by reference as if fully described herein, along with a copy attached to the appendix. Each flexible strip 321 may consist of a flexible polymer circuit strip 321 including a polyimide layer. The hinge 328 of the flexible polymer circuit strip may be reinforced with a thread of some length of any suitable material, e.g., a thread that is flexible and provides tensile support to the strip. In some embodiments, the length of the thread extends to the entire length of each strip including the hinge. The thread may include any suitable thread. For example, the thread may include any one or more of ultra-high molecular weight polyethylene threads or threads spun from liquid crystal polymers. Each flexible polymer circuit strip, its length of thread, and elongated elastic support element may be fixed together with a suitable adhesive, such as epoxy, and then coated with thermoplastic polymer resin shrink packaging (PET) or any other suitable coating. Windows (or openings) may be created in the PET coating using a laser, mechanical removal, or any other suitable method to expose the electrodes. Alternatively, before shrinkage, the PET coating may have windows that already exist. The flexible polymer circuit strip may further include a conductive polymer coating, such as poly(3,4-ethylenedioxythiophene) (PEDOT) or poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), on each electrode to protect the electrodes, reduce input impedance, and help improve the signal-to-noise ratio. The conductive polymer coating may be applied to each electrode by immersing the electrodes in a solution containing the conductive polymer coating and then passing an electric current through the electrodes. As the current passes through each electrode, the conductive polymer coating adheres to the surface of the electrodes. To help reduce the likelihood of the conductive polymer coating being damaged by friction on the sheath or contact with other objects, the techniques of the present disclosure may include forming openings in the PET coating using a laser, mechanical removal, or any other suitable method to expose only a portion of each electrode.In other words, rather than removing the PET coating to expose the entire surface of the electrode, the techniques of the present disclosure may include removing smaller portions of the PET coating to expose only a portion of the electrode surface by forming small openings through the PET coating. By including small openings through the PET, the PET can provide protection to the conductive polymer coating positioned within each opening by preventing the conductive polymer coating from coming into contact with the sheath or other objects. The openings may be sized, molded, and positioned to help reduce the possibility of the conductive polymer coating coming into contact with the sheath or other objects, while also ensuring that the electrode can still detect electrical signals from the heart. Reduced damage to the conductive polymer coating may result in more accurate signals from the electrode, and / or a reduced risk of health threats due to the coating detaching onto the patient's heart and / or vascular structure. Details of the rope or thread, PET shrink wrap, windows in the PET shrink wrap, and conductive polymer coating are shown and described in the present applicant's published patent application, U.S. Patent Application Publication No. 20210187254A1 (Agent Reference Number BIO6243), which is incorporated by reference with the appendices.

[0099] Referring to Figure 10, the system 410 includes a catheter with a basket assembly 328, an ablation power generator 434, and a switch circuit 451 which may be provided in the PIU to establish electrical communication between the catheter and the processing unit 441. The switch circuit 451 controls the selected electrodes E1-E of the basket assembly 328. N+1The user input device 444 is configured to respond to the activation of the electrical connection / disconnection of electrodes E1-E10 (for example, in Figures 8 and 9), and the ablation power generator 434 and / or processing unit 441 cause these electrodes to function as "active" or "returned" in an electrical circuit used for a user-selected operating mode between tissue electrical activity sensing (e.g., mapping), unipolar ablation, and bipolar ablation. Such selected electrical connection / disconnection may be further adjusted based on the detection by the force sensor assembly 320, in the manner described above, of the contact between electrodes E1-E10 of the basket assembly and cardiac tissue, and / or the degree of such contact exceeding a predetermined threshold. Alternatively, the basket assembly 328 may include a plurality of force sensors FS1-FS10, each force sensor configured to detect contact between its respective electrode Ei and cardiac tissue 412, and the force sensors FS1-FS10 may be located, for example, at either the distal or proximal end of a spine. Therefore, the switch circuit 451 can create one or more effective composite electrodes from selected electrodes on the catheter by short-circuiting only the electrodes detected to be in contact with tissue and disconnecting electrodes detected not in contact with tissue or not in sufficient contact with tissue, with respect to a predetermined threshold contact force, in order to avoid applying excessive current to the patient and to apply current only when necessary.

[0100] In the embodiment shown in Figure 10, the switch circuit 451 includes switches SW1 to SW10, each switch providing a three-way switch (or double-throw switch) to each electrode, configured to connect each electrode to one of at least three settings at any given time. The three settings for each switch SWi are as follows: (i) Setting S1, which connects to the ablation power generator 434 as the “active” electrode for ablation, including unipolar ablation and bipolar ablation. (ii) Setting S2, which connects to the processing unit 41 as a “return” electrode for bipolar ablation that senses cardiac electrical signals, and (iii) Setting S3 to connect to the float F as an inert electrode that is not in contact with the tissue or is in insufficient contact with the tissue in either unipolar ablation or bipolar ablation.

[0101] In some embodiments, the basket assembly 328 also includes an electrode ERef, for example, a ring electrode positioned at the center of the basket assembly, for example, on a central longitudinal tube 321 extending between the proximal and distal ends of the basket assembly. The electrode ERef has a bidirectional switch SWW that provides (i) a setting S5 to connect to the processing unit as a “return” electrode or TRUREF® electrode when the system is operating in unipolar ablation mode, and (ii) a setting S6 to connect to the float as an inert electrode.

[0102] Referring to Figures 10, 11, 12, and 13, only one spine of the basket assembly and the electrodes E1, E2, E3, E4, E9, and E10 on it are briefly described and understood to represent multiple spines of the basket assembly and their electrodes. As shown in the embodiment of Figure 10, electrodes E1 to E10 are arranged on the spine, and each pair of electrodes is positioned closer to each other than the other pair of electrodes. As shown in Figures 11, 12, and 13, electrode pairs E3 and E4 are not in contact with tissue T, while electrode pairs E1, E2 and E9 and E10 are in contact with tissue T. Thus, in some embodiments, the system controller instructs the processing unit 441 to execute the force sensing module 468 to activate the force sensors FS1 to FS10. In response to the force sensing module 468 detecting electrodes E1, E2, E9, and E10 with tissue contact and electrodes E3 and E4 that do not have contact (or do not have sufficient contact), the system instructs the processing unit 441 to execute the switch control module 473 to control the switch circuit 451 when setting switches SW3 and SW4 for electrodes E3 and E4 to the float setting S3, as shown in Figures 11, 12, and 13. The switch settings of switches SW1, SW2, SW9, and SW10 for the remaining electrodes E1, E2, E9, and E10 that are in contact with tissue (or have sufficient contact above the contact threshold) depend on the operating mode selected by the user.

[0103] To sense the electrical activity of cardiac tissue, the user activates a first control switch to select tissue sensing (for example, for mapping). In response, the system controller instructs the processing unit 441 to execute the tissue sensing subroutine 474 of the switch control module 473. Thus, as shown in the embodiment of Figure 11, the switch circuit 451 sets switches SW1, SW2, SW9, and SW10 at electrodes E1, E2, E9, and E10, respectively, to setting S2 when connecting each of these electrodes to the processing unit 41 as a “return” electrode for sensing tissue signals, including IEGM signals from cardiac tissue, and the system controller instructs the processing unit 441 to execute the tissue sensing subroutine 474 to receive such signals and process them into a potential diagram. The switch circuit 451 also sets switch SWW at electrode EREF to setting S3 when connecting the electrode to float S6 as an “inactive” electrode. The current path from cardiac tissue to the processing unit is shown by a dotted line.

[0104] To ablate cardiac tissue, the user activates a first control switch to select ablation and a second control switch to select unipolar or bipolar ablation. If unipolar ablation is selected, the system controller instructs the processing unit 441 to execute the unipolar subroutine 475 of the switch control module 473. Thus, as shown in the embodiment of Figure 12, the switch circuit 451 sets the switches SW1, SW2, SW9, SW10 at electrodes E1, E2, E9, and E10, respectively, to setting S1, which connects these electrodes to the ablation power generator 434 as "active" for delivering ablation energy, including pulse energy at IRE, and sets the switch SWW at electrode EREF to setting S5, which connects this electrode to the processing unit 441 as a "return" electrode. The current path from the ablation power generator 434 to the processing unit 441 is shown by a dotted line, and the composite electrode is formed from a "short circuit" of electrodes E1, E2, E9, and E10 that are in contact with the tissue, and ablation power is not supplied to electrodes E3 and E4 that are disconnected from the circuit. Therefore, ablation is applied only when the electrodes are in contact (or there is sufficient contact above the threshold contact force), and the patient is exposed only to the required amount of ablation output.

[0105] To ablate cardiac tissue in a bipolar manner, the user selects bipolar ablation using a second control switch. The system controller then instructs the processing unit 441 to execute the bipolar subroutine 476 of the switch control module 473. Thus, as shown in the embodiment of Figure 13, the switch circuit 51 sets the respective switches SW1 and SW10 at electrodes E1 and E10 to setting S1, which connects these electrodes to the ablation power generator 434 as "active" electrodes for delivering ablation energy, including pulse energy at IRE, while the respective switches SW2 and SW9 at electrodes E2 and E9 are set to setting S2, which connects these electrodes to the processing unit 441 as "return" electrodes. The switch circuit 451 also sets the switch SWW at electrode EREF to setting S6, which connects the electrode to the float as an "inactive" electrode. The current path from the ablation power generator 434 to the processing unit 441 is shown by a dotted line, and the composite electrode is formed from the "short-circuit" circuit of electrodes E1 and E10.

[0106] In the IRE procedure, pulse frequency ablation (PFA) signals are delivered to the "active" electrode of either unipolar or bipolar ablation, which has one or more pulse trains ("pulse bursts") with pauses between pulse trains. The pauses allow the tissue to cool and the muscle to relax if contraction occurs.

[0107] In the embodiment of the basket assembly shown in Figure 9, when used in tubular regions such as pulmonary veins, contact with tissue occurs most frequently around the equatorial region of the basket assembly, including electrodes E5, E6, E7, E8 on selected or all spines of the basket assembly. Therefore, the processing unit activates a switch circuit to electrically connect these equatorial electrodes, forming one or more composite electrodes for ablating the pulmonary veins. Bipolar ablation can be achieved with electrical energy from an ablation power generator, depending on the electrical connection provided by the switch circuit, for example, moving from equatorial electrodes E5, E6, E7, E8 on spine 321A to equatorial electrodes E5, E6, E7, E8 on spine 321B or spine 321C, skipping over spine 321B, or even to the central ring electrode 340. Unipolar ablation can be achieved by moving electrical energy from the ablation power generator from equatorial electrodes E5, E6, E7, E8 to a surface electrode 38 on the patient's skin (see Figure 1).

[0108] The above description is provided in relation to preferred embodiments of the present invention as of now. Those skilled in the art will recognize that modifications and changes can be made to the described structures without departing in a substantial manner from the principles, spirit, and scope of the invention. Any feature or structure disclosed in one embodiment may be incorporated, as needed or as appropriate, in place of or in addition to other features of other embodiments. As will be understood by those skilled in the art, the drawings are not necessarily to scale. Therefore, the above description should not be read as relating only to the exact structures described and illustrated in the accompanying drawings, but rather as being consistent with and supporting the claims, which are deemed to have the most complete and fair scope below.

[0109] It should be noted that the electrodes described and illustrated herein are not limited to mapping (i.e., sensing or recording signals) but can be used in bipolar or unipolar modes alone, or in combination with mapping or sensing functions, to deliver energy such as RF (alternating current cycle) or IRE (DC pulse). In IRE applications, for example, the electrodes may be configured to deliver at least 900V per electrode with a current of at least 10 amperes over a number of pulses sufficient to induce cellular apoptosis. It should also be noted that the mapping and ablation described herein may be applied to tissues and organs other than the heart.

[0110] It should be understood that any of the embodiments described herein may include a variety of other features in addition to or instead of those described above. For example, any of the embodiments described herein may include one or more of the various features disclosed in any of the various references incorporated herein by reference.

[0111] It should be understood that one or more of the teachings, expressions, embodiments, examples, etc. described herein may be combined with one or more of the other teachings, expressions, embodiments, examples, etc. described herein. Therefore, the above teachings, expressions, embodiments, examples, etc. should not be considered in isolation from each other. Various preferred ways in which the teachings herein may be combined will be readily apparent to those skilled in the art in view of the teachings herein. Such modifications and variations are intended to be included within the claims.

[0112] Any patent, publication, or other disclosure material that is said to be incorporated herein by reference will be incorporated herein only to the extent that the incorporated material, in whole or in part, does not contradict any existing definitions, views, or other disclosure material contained herein. Any disclosure expressly contained herein, either by itself or to the extent necessary, shall take precedence over any conflicting statements incorporated herein by reference. Any material, or any part thereof, that is said to be incorporated herein by reference but contradicts any existing definitions, views, or other disclosure material contained herein will be incorporated only to the extent that there is no conflict between the incorporated material and the existing disclosure material.

[0113] While various modifications of the present invention have been illustrated and described, further adaptations of the methods and systems described herein can be achieved by appropriate modifications by those skilled in the art without departing from the scope of the invention. Some of these possible modifications have been mentioned, but others will be obvious to those skilled in the art. For example, the embodiments, modifications, geometric shapes, materials, dimensions, proportions, processes, etc., discussed above are illustrative and not essential. Therefore, it should be understood that the scope of the invention is considered with respect to the following claims and is not limited to the structural and operational details shown and described herein and in the drawings.

[0114] [Implementation Method] (1) A catheter system, A catheter comprising a basket assembly having a plurality of electrodes and a contact force sensor for receiving signals from cardiac tissue, wherein the contact force sensor is configured to generate a first contact signal representing a contact force acting on the basket assembly, An ablation power generator configured to deliver energy into the cardiac tissue by energizing one or more of the plurality of electrodes, An impedance circuit configured to send current to each electrode and generate a second contact signal for each electrode representing contact between the electrode and cardiac tissue, A processor configured to receive the first contact signal and the second contact signal, identify the selected electrode in contact with the tissue, and generate a switch signal in response to the first contact signal and the second contact signal, A catheter system comprising: a switch circuit configured to electrically connect only the selected electrode to the ablation power generator in response to the switch signal when forming a composite ablation electrode. (2) The catheter system according to Embodiment 1, wherein the switch circuit is configured to electrically connect the selected electrodes for bipolar ablation. (3) The catheter system according to Embodiment 1, wherein the switch circuit is configured to electrically connect the selected electrode for unipolar ablation. (4) The catheter system according to Embodiment 1, wherein the basket assembly includes a shaft defining a longitudinal axis, a plurality of elongated strips converging at a distal end and a proximal end, and an elongated pusher extending through the shaft and movable longitudinally relative to the shaft, the elongated pusher having a distal end connected to the distal end of the strips such that the proximal movement of the elongated pusher relative to the shaft along the longitudinal axis bends the strips outward when the basket assembly is expanded. (5) The catheter system according to Embodiment 4, wherein the catheter includes a position sensor housed within the pusher.

[0115] (6) The catheter system according to Embodiment 4, wherein the basket assembly is folded when the elongated pusher is moved distally along the longitudinal axis relative to the shaft after proximal movement. (7) The catheter system according to Embodiment 1, wherein the contact force sensor is housed within the shaft at the proximal end of the shaft. (8) The catheter system according to Embodiment 1, wherein the contact force sensor includes a first end, a second end, and a deformable spring between those ends. (9) The catheter system according to Embodiment 8, wherein the contact force sensor further includes a magnetic field transmitter housed at the first end and a magnetic field receiver housed at the second end, the magnetic field receiver being configured to respond to the magnetic field transmitter by generating a displacement signal indicating a displacement in the spatial relationship between the magnetic field transmitter and the magnetic field sensor. (10) The catheter system according to Embodiment 9, wherein the displacement signal indicates the distance and angular direction of the displacement.

[0116] (11) A catheter system, A catheter having multiple electrodes and multiple force sensors, wherein each force sensor is configured to generate a contact signal representing the contact force acting on each electrode, an ablation power generator configured to supply current to the plurality of electrodes, A processor configured to receive each contact signal and generate each switch signal for each electrode in response, A switch circuit is configured to electrically connect only the selected electrode in contact with the tissue to the ablation power generator in response to each switch signal when forming composite electrodes. A catheter system equipped with the following features. (12) The catheter system according to embodiment 11, further comprising a user input device configured to operate the ablation power generator. (13) The catheter system according to embodiment 11, wherein the processor is configured to operate the ablation power generator in a biphasic mode. (14) The catheter system according to embodiment 11, wherein the processor is configured to operate the switch circuit between a unipolar mode and a bipolar mode. (15) The catheter system according to embodiment 11, wherein the processing unit is configured to operate the switch circuit between tissue sensing mode and ablation mode.

[0117] (16) The catheter system according to embodiment 11, wherein the processing unit is configured to activate the switch circuit in response to a control signal from the user input device. (17) The catheter system according to embodiment 11, wherein the catheter further comprises a reference electrode. (18) The catheter system according to embodiment 17, wherein the reference electrode is configured to avoid tissue contact. (19) The catheter system according to Embodiment 11, wherein the switch circuit includes a first switch configured to connect each electrode to the ablation power generator, a second switch configured to connect each electrode to a processing unit, and a third switch as a float. (20) The catheter system according to embodiment 19, wherein the processing unit is configured to activate the switch circuit in response to the contact signal to connect each of the electrodes to the ablation power generator via the first switch.

Claims

1. It is a catheter system, A catheter comprising a basket assembly having a plurality of electrodes and a contact force sensor for receiving signals from cardiac tissue, wherein the contact force sensor is configured to generate a first contact signal representing a contact force acting on the basket assembly, An ablation power generator configured to deliver energy into the cardiac tissue by energizing one or more of the plurality of electrodes, An impedance circuit configured to send current to each electrode and generate a second contact signal for each electrode representing contact between the electrode and cardiac tissue, A processor configured to receive the first contact signal and the second contact signal, identify the selected electrode in contact with the tissue, and generate a switch signal in response to the first contact signal and the second contact signal, A catheter system comprising: a switch circuit configured to electrically connect only the selected electrode to the ablation power generator in response to the switch signal when forming a composite ablation electrode.

2. The catheter system according to claim 1, wherein the switch circuit is configured to electrically connect the selected electrodes for bipolar ablation.

3. The catheter system according to claim 1, wherein the switch circuit is configured to electrically connect the selected electrodes for unipolar ablation.

4. The catheter system according to claim 1, wherein the basket assembly includes a shaft defining a longitudinal axis, a plurality of elongated strips converging at a distal end and a proximal end, and an elongated pusher extending through the shaft and movable longitudinally relative to the shaft, the elongated pusher having a distal end connected to the distal end of the strips such that the proximal movement of the elongated pusher relative to the shaft along the longitudinal axis bends the strips outward as the basket assembly expands.

5. The catheter system according to claim 4, wherein the catheter includes a position sensor housed within the pusher.

6. The catheter system according to claim 4, wherein the basket assembly is folded when the elongated pusher is moved distally along the longitudinal axis relative to the shaft after proximal movement.

7. The catheter system according to claim 1, wherein the contact force sensor is housed within the shaft at the proximal end of the shaft.

8. The catheter system according to claim 1, wherein the contact force sensor includes a first end, a second end, and a deformable spring between those ends.

9. The catheter system according to claim 8, wherein the contact force sensor further includes a magnetic field transmitter housed at the first end and a magnetic field receiver housed at the second end, the magnetic field receiver being configured to respond to the magnetic field transmitter when generating a displacement signal indicating a displacement in the spatial relationship between the magnetic field transmitter and the magnetic field sensor.

10. The catheter system according to claim 9, wherein the displacement signal indicates the distance and angular direction of the displacement.

11. It is a catheter system, A catheter having multiple electrodes and multiple force sensors, wherein each force sensor is configured to generate a contact signal representing the contact force acting on each electrode, an ablation power generator configured to supply current to the plurality of electrodes, A processor configured to receive each contact signal and generate each switch signal for each electrode in response, A switch circuit is configured to electrically connect only the selected electrode in contact with the tissue to the ablation power generator in response to each switch signal when forming composite electrodes. A catheter system equipped with the following features.

12. The catheter system according to claim 11, further comprising a user input device configured to operate the ablation power generator.

13. The catheter system according to claim 11, wherein the processor is configured to operate the ablation power generator in a biphasic mode.

14. The catheter system according to claim 11, wherein the processor is configured to operate the switch circuit between a unipolar mode and a bipolar mode.

15. The catheter system according to claim 11, wherein the processing unit is configured to activate the switch circuit between tissue sensing mode and ablation mode.

16. The catheter system according to claim 11, wherein the processing unit is configured to activate the switch circuit in response to a control signal from the user input device.

17. The catheter system according to claim 11, wherein the catheter further comprises a reference electrode.

18. The catheter system according to claim 17, wherein the reference electrode is configured to avoid tissue contact.

19. The catheter system according to claim 11, wherein the switch circuit includes a first switch configured to connect each electrode to the ablation power generator, a second switch configured to connect each electrode to a processing unit, and a third switch as a float.

20. The catheter system according to claim 19, wherein the processing unit is configured to activate the switch circuit in response to the contact signal to connect each of the electrodes to the ablation power generator via the first switch.

Images