CN118000897A

CN118000897A - Catheter, system and method for combining ablation modalities

Info

Publication number: CN118000897A
Application number: CN202410257317.7A
Authority: CN
Inventors: T·夏尔马; J·马弗尔; A·戈瓦里; A·维尔马
Original assignee: Biosense Webster Israel Ltd
Current assignee: Biosense Webster Israel Ltd
Priority date: 2022-09-11
Filing date: 2022-11-25
Publication date: 2024-05-10
Also published as: CN117598771A; CN118000896A; CN117598772A

Abstract

The title of the present disclosure is "catheters, systems, and methods for combining ablation modalities". The disclosed technology includes a method of ablating tissue, the method including positioning an electrode in contact with the tissue, and applying a first ablation signal to the tissue. The method may include forming a first ablation site including a first depth, wherein the temperature of the tissue has little or no first temperature change. The method may include applying a second ablation signal to the tissue that is different from the first ablation signal. Applying the second ablation signal to the tissue may include forming a second ablation focus including a second depth, and generating a second temperature change in the tissue, the second temperature change differing from the first temperature change by at least 10 ℃. The method may include forming a combined ablation site including the first ablation site and the second ablation site and including a combined size. The combined depth may be about 20% to about 40% greater than either of the first depth and the second dimension.

Description

Catheter, system and method for combining ablation modalities

Technical Field

The present invention relates to catheters particularly suited for performing pulsed field ablation in or near the heart. Catheters may also be used for mapping and/or thermal ablation using radio frequency electrical signals.

Background

When a region of cardiac tissue abnormally conducts electrical signals to adjacent tissue, an arrhythmia, such as atrial fibrillation, will occur, disrupting the normal cardiac cycle and causing arrhythmia. The sources of unwanted signals are typically located in the tissues of the atria and ventricles. Regardless of the source, unwanted signals are conducted elsewhere through the heart tissue where they can trigger or sustain an arrhythmia.

Treatment of cardiac arrhythmias may include disrupting the conductive path of the electrical signal to cause the arrhythmia to cease, or modifying the propagation of unwanted electrical signals from one portion of the heart to another. Such procedures typically include a two-step process: (1) mapping; and (2) ablation. During mapping, a catheter having an end effector, preferably having a high density of electrodes, is moved across the target tissue, electrical signals are acquired from each electrode, and a map is generated based on the acquired signals. During ablation, non-conductive foci are formed at areas selected based on the map to disrupt electrical signals passing through those areas. The most common ablation technique today involves applying Radio Frequency Ablation (RFA) electrical signals to the tissue via electrodes to generate heat. Irreversible electroporation (IRE) ablation is a recently developed technique that involves applying short duration high voltage pulses across tissue to cause cell death, sometimes referred to as Pulsed Field Ablation (PFA). Typically, RFA and PFA are applied as separate and distinct technologies. In the context of the present disclosure, RFA may be interchangeably referred to as RF, and PFA may be referred to as PF.

Different targets for mapping, ablation with RF signals, and IRE ablation often lead to different catheter design objectives. As a non-exhaustive list, some catheters with circular, semicircular, or spiral end effectors for mapping and/or ablation are described in the following patents and patent applications: U.S. patent No. 6,973,339, U.S. patent No. 7,371,232, U.S. patent No. 8,275,440, U.S. patent No. 8,475,450, U.S. patent No. 8,600,472, U.S. patent No. 8,608,735, U.S. patent No. 9,050,010, U.S. patent No. 9,788,893, U.S. patent No. 9,848,948, U.S. patent publication No. 2017/0100188, U.S. patent publication No. 2021/0369338, U.S. patent application No. 17/570,829, U.S. provisional patent application No. 63/336,094, and U.S. provisional patent application No. 63/220,312, each of which is incorporated herein by reference, a copy of which is provided in the appendix.

Disclosure of Invention

In general, examples presented herein may include a method of ablating tissue. The method may include positioning an electrode in contact with tissue, and applying a first ablation signal to the tissue with the electrode. Applying the first ablation signal to the tissue may include forming a first ablation focus including a first depth, wherein the temperature of the tissue has little or no first temperature change.

The method may include applying a second ablation signal, different from the first ablation signal, to the tissue with the electrode. Applying the second ablation signal to the tissue may include forming a second ablation focus including a second depth, and generating a second temperature change in the tissue that differs from the first temperature change by at least 10 ℃.

The method may include forming a combination ablation site including a first ablation site and a second ablation site and including a combined size. The combined depth may be about 20% to about 40% greater than either of the first depth and the second dimension.

The first and second ablation signals may be applied to the tissue at least sequentially or simultaneously.

The positioning step may include applying a contact force between the tissue and the electrode of about 5 grams to about 40 grams.

The first ablation signal may be one of a Radio Frequency (RF) signal or a Pulsed Field (PF) signal, and the second ablation signal is the other of the RF signal or the PF signal.

The method may further comprise: setting the power of the RF signal to about 1 watt to about 400 watts; maintaining the RF signal for about 1 second to about 60 seconds; and generating one of a first temperature change or a second temperature change of about 20 ℃ to about 70 ℃.

The method may further include setting the voltage of the PF signal to about 900 volts to about 3000 volts.

The RF signal may form one of a first depth or a second depth between about 3mm to about 5 mm.

The PF signal may form one of a first depth or a second depth between about 4mm to about 6 mm.

The disclosed technology may include a system for electrophysiological use. The system may include: an Alternating Current (AC) signal generator configured to provide a radio frequency signal at high power; a Direct Current (DC) signal generator configured to provide a high voltage pulse; and a catheter having an end effector.

The end effector may be electrically coupled to the AC signal generator and the DC signal generator. The end effector may include at least one electrode disposed on the end effector such that the at least one electrode delivers a high voltage pulse from the at least one electrode to organ tissue within a patient, to first and second return electrodes coupled to the exterior of the patient's body, and a radio frequency signal between the at least one electrode and one of the first or second return electrodes.

The radio frequency signal and the high voltage pulse may be applied to the organ tissue sequentially or simultaneously.

The end effector may include a cylindrical member having a distal tip electrode and irrigation ports disposed on the cylindrical member to provide irrigation fluid proximate the distal tip electrode.

The distal tip electrode may be coupled to a force sensor. The radio frequency signal may be applied with a contact force of about 5 grams or more. The radio frequency signal may be provided with a power of at least 25 watts at a frequency of about 350kHz to about 500 kHz. The radio frequency signal may include a frequency of 350kHz to about 500kHz and the radio frequency signal may be provided for a duration of at least 1 second.

The high voltage pulse may include an amplitude of at least 800V. Each of the high voltage pulses may have a duration of less than 20 microseconds. Multiple high voltage pulses may provide a burst of about 100 microseconds. A time gap of any value selected from 0.3 ms to 1000 ms may be provided between adjacent bursts. Multiple bursts may provide PFA bursts. The PFA burst may comprise any value between 2 bursts and 100 bursts, wherein the duration of the PFA burst comprises any value selected from 0 milliseconds to 500 milliseconds. The high voltage pulse may provide about 60 joules or less.

Drawings

The above-described and further aspects of the present invention will be further discussed with reference to the following description, taken in conjunction with the accompanying drawings, in which like numerals indicate like structural elements and features in the various figures. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. The drawings depict one or more implementations of the present devices, systems, and methods by way of example only, not by way of limitation.

FIG. 1 is a schematic illustration of a medical system including an exemplary medical probe that may be used in accordance with the disclosed technology;

FIG. 2A is a side view of a catheter for use with the system of FIG. 1 in accordance with the disclosed technology;

FIG. 2B is a perspective view of a catheter for use with the system of FIG. 1, in accordance with the disclosed technology;

FIG. 3 is a schematic cross-sectional view of a heart chamber having a conduit within the chamber in contact with the heart wall in accordance with the disclosed technology;

FIGS. 4A and 4B are pictures depicting depth of tissue treated with RF energy and PFA energy in accordance with the disclosed techniques;

FIG. 5 illustrates a flow chart of a method of ablating tissue using RF energy and PFA energy in accordance with the disclosed technology;

FIG. 6A illustrates a basket catheter in accordance with the disclosed technology;

FIG. 6B illustrates a circular catheter in accordance with the disclosed technology;

Fig. 6C illustrates a planar array catheter in accordance with the disclosed technology.

Detailed Description

The incorporation by reference of documents herein is to be considered an integral part of the present application except that to the extent that any term is defined in such incorporated document in a manner that contradicts the definition made explicitly or implicitly in this specification, only the definition in this specification should be considered.

Although example embodiments of the disclosed technology are explained in detail herein, it should be understood that other embodiments are contemplated. Accordingly, it is not intended to limit the scope of the disclosed technology to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The disclosed technology is capable of other embodiments and of being practiced or of being carried out in various ways. As will be appreciated by those skilled in the relevant art in light of the teachings herein, features of the embodiments disclosed herein (including those disclosed in the attached appendix) may be combined.

As used herein, the term "about" or "approximately" for any numerical value or range indicates a suitable dimensional tolerance that allows a collection of components or elements to achieve the intended purpose thereof as described herein. More specifically, "about" or "approximately" may refer to a range of values of ±20% of the recited values, for example "about 90%" may refer to a range of values of 71% to 99%.

As discussed herein, the term "ablation" as it relates to the devices and corresponding systems of the present disclosure refers to components and structural features configured to reduce or prevent the generation of unstable cardiac signals. Non-thermal ablation includes the use of irreversible electroporation (IRE) to cause cell death, interchangeably referred to herein as Pulsed Electric Field (PEF) and Pulsed Field Ablation (PFA). Thermal ablation includes the use of extreme temperatures to cause cell death and includes RF ablation. "ablation" as used throughout the present disclosure, when referring to the devices and corresponding systems of the present disclosure, refers to ablation of cardiac tissue for certain conditions, including, but not limited to, arrhythmia, atrial flutter ablation, pulmonary vein isolation, supraventricular tachycardia ablation, and ventricular tachycardia ablation. As will be appreciated by those skilled in the relevant art, the term "ablation" as it relates generally to known methods, devices and systems includes various forms of body tissue ablation.

As discussed herein, the terms "bipolar" and "monopolar" when used in reference to an ablation scheme describe an ablation scheme that differs in terms of current path and electric field distribution. "bipolar" refers to an ablation protocol that utilizes a current path between two electrodes, both of which are positioned at a treatment site inside the body; the current density and the current flux density at each of the two electrodes are typically approximately equal. "monopolar" refers to an ablation procedure utilizing a current path between two electrodes, with one electrode having a high current density and a high electrical flux density positioned at the treatment site and a second electrode having a relatively lower current density and a lower electrical flux density positioned away from the treatment site, typically outside the body via a contact patch.

As discussed herein, the terms "biphasic pulse" and "monophasic pulse" refer to the corresponding electrical signals. A "biphasic pulse" refers to an electrical signal having a positive voltage phase pulse (referred to herein as the "positive phase") and a negative voltage phase pulse (referred to herein as the "negative phase"). "monophasic pulse" refers to an electrical signal having only a positive phase or only a negative phase. Preferably, the system providing biphasic pulses is configured to prevent the application of a direct current voltage (DC) to the patient. For example, the average voltage of the biphasic pulse may be zero volts relative to ground or other common reference voltage. Additionally or alternatively, the system may include a capacitor or other protective component. Voltage amplitudes of biphasic and/or monophasic pulses are described herein, it being understood that the expressed voltage amplitudes are absolute values of the approximate peak amplitudes of each of the positive voltage phase and/or the negative voltage phase. Each phase of the biphasic pulse and the monophasic pulse preferably has a square shape with a substantially constant voltage amplitude during a substantial portion of the phase duration. The phases of the biphasic pulse are separated in time by an inter-phase delay. The inter-phase delay duration is preferably less than or approximately equal to the duration of the phase of the biphasic pulse. The inter-phase delay duration is more preferably about 25% of the duration of the phase of the biphasic pulse.

As discussed herein, the terms "tubular" and "tube" are to be understood in a broad sense and are not limited to structures that are right circular cylinders or that are entirely circumferential in cross-section or have a uniform cross-section throughout their length. For example, the tubular structure is generally shown as a substantially right circular cylinder structure. However, the tubular structure may have a tapered or curved outer surface without departing from the scope of the present disclosure.

Referring to fig. 1, an exemplary catheter-based electrophysiology mapping and ablation system 10 is shown. The system 10 includes a plurality of catheters that are percutaneously inserted by a physician 24 through the vascular system of a patient into a chamber or vascular structure of the heart 12. Typically, the delivery sheath catheter is inserted into the left atrium or the right atrium near the desired location in the heart 12. Multiple catheters may then be inserted into the delivery sheath catheter in order to reach the desired location. The plurality of catheters may include catheters dedicated to sensing Intracardiac Electrogram (IEGM) signals, catheters dedicated to ablation, and/or catheters dedicated to both sensing and ablation. An exemplary catheter 14 configured for sensing IEGM is shown herein. The physician 24 brings the distal tip 28 of the catheter 14 into contact with the heart wall for sensing a target site in the heart 12. For ablation, the physician 24 would similarly bring the distal end of the ablation catheter to the target site for ablation.

The catheter 14 is an exemplary catheter comprising one (preferably multiple) electrodes 26 optionally distributed over multiple ridges 22 at a distal tip 28 and configured to sense IEGM signals. Catheter 14 may additionally include a position sensor 29 embedded in or near distal tip 28 for tracking the position and orientation of distal tip 28. Optionally and preferably, the position sensor 29 is a magnetic-based position sensor comprising three magnetic coils for sensing three-dimensional (3D) position and orientation.

The magnetic-based position sensor 29 is operable with a placemat 25 that includes a plurality of magnetic coils 32 configured to generate a magnetic field in a predetermined workspace. The real-time position of the distal tip 28 of the catheter 14 may be tracked based on the magnetic field generated with the location pad 25 and sensed by the magnetic-based position sensor 29. Details of magnetic-based position sensing techniques are described in U.S. Pat. nos. 5,5391,199、5,443,489、5,558,091、6,172,499、6,239,724、6,332,089、6,484,118、6,618,612、6,690,963、6,788,967 and 6,892,091.

The system 10 includes one or more electrode patches 38 that are positioned in contact with the skin of the patient 23 to establish a positional reference for impedance-based tracking of the location pad 25 and the electrode 26. For impedance-based tracking, current is directed toward the electrodes 26 and sensed at the electrode skin patches 38 so that the position of each electrode can be triangulated via the electrode patches 38. Details of impedance-based location tracking techniques are described in U.S. patent nos. 7,536,218, 7,756,576, 7,848,787, 7,869,865, and 8,456,182. The electrode patch(s) 38 may serve as return electrodes (also referred to as indifferent electrodes) during the monopolar mode of ablation, whereby electrical energy is provided by one or more electrodes on the catheter such that the electrical energy completes a circuit to the indifferent (or return) electrode 38 via tissue. In practice, where the surface area of the electrode patch 38 is not large enough to handle power transfer, two separate return electrode patches (which have a surface area greater than that of the patch 38) are used separately from the electrode patch 38.

Recorder 11 displays an electrogram 21 captured with body surface ECG electrodes 18 and an Intracardiac Electrogram (IEGM) captured with electrodes 26 of catheter 14. Recorder 11 may include pacing capabilities for pacing the heart rhythm and/or may be electrically connected to a separate pacemaker.

The system 10 may include an ablation energy generator 50 adapted to conduct ablation energy to one or more electrodes at a distal tip of a catheter configured for ablation. The energy generated by ablation energy generator 50 may include, but is not limited to, radio Frequency (RF) energy or Pulsed Field Ablation (PFA) energy, including monopolar or bipolar high voltage DC pulses that may be used to achieve irreversible electroporation (IRE), or a combination thereof.

The Patient Interface Unit (PIU) 30 is an interface configured to establish electrical communication between a catheter, electrophysiological equipment, a power source, and a workstation 55 for controlling operation of the system 10. The electrophysiological equipment of system 10 can include, for example, a plurality of catheters, location pads 25, body surface ECG electrodes 18, electrode patches 38, an ablation energy generator 50, and a recorder 11. Optionally and preferably, the PIU 30 additionally includes processing power for enabling real-time calculation of the position of the catheter and for performing ECG calculations.

The workstation 55 includes memory, a processor unit with memory or storage loaded with appropriate operating software, and user interface capabilities. Workstation 55 may provide a number of functions, optionally including: (1) Three-dimensional (3D) modeling of endocardial anatomy and rendering of the model or anatomical map 20 for display on display device 27; (2) Displaying the activation sequence (or other data) compiled from the recorded electrogram 21 on the display device 27 with a representative visual marker or image superimposed on the rendered anatomical map 20; (3) Displaying real-time positions and orientations of a plurality of catheters within a heart chamber; and (5) displaying a site of interest (such as a site to which ablation energy has been applied) on the display device 27. A commercial product embodying elements of system 10 is available from the Biosense Webster, inc.,31A Technology Drive,Irvine,CA 92618 as a CARTO ^TM system.

As shown in fig. 2A, the catheter 14 may include an elongate catheter body 17, a deflectable intermediate section 19, a distal section 13 carrying at least a tip electrode 15 on a distal tip 28 thereof, and a control handle 16. The catheter 14 may be a steerable multi-electrode lumen catheter with deflectable tips designed to facilitate electrophysiological mapping of the heart 12 and to deliver Radio Frequency (RF) and Pulsed Field (PF) currents to the tip electrode 15 for ablation purposes. A physician 24, such as a cardiologist, may insert the catheter 14 through the vascular system of the patient 23 such that the distal section 13 of the catheter enters the chamber of the patient's heart 12. Physician 24 pushes the catheter so that distal tip 28 of the catheter engages endocardial tissue at the desired location or locations. Catheter 14 is connected to console 55 by a suitable connector at its proximal end. The console 55 may include an ablation energy generator 50 that supplies high frequency electrical energy (AC or DC) via the catheter 14 for ablating tissue in the heart 12 at the location where the distal section 13 is engaged. For ablation, the catheter 14 may be used in combination with a dispersion pad (e.g., a return electrode or an indifferent electrode). In this regard, the catheter 14 may include a shaft measuring 7.5F with an 8F ring electrode. Catheter 14 may also have a force sensing system near distal tip electrode 15 that provides real-time measurement of the contact force between catheter tip 15 and the wall of heart 12 (and the contact angle between tip electrode 15 and tissue).

As shown in fig. 2B, the distal tip section 13 may include an electrode assembly 15 and at least one micro-component having an atraumatic distal end adapted for direct contact with target tissue. The catheter body 17 may have a longitudinal axis, and an intermediate section 19 distal to the catheter body 17 that may be deflected off-axis unidirectionally or bidirectionally from the catheter body 12. Distal to the intermediate section 19 is an electrode assembly carrying at least one electrode 15. Proximal to the catheter body is a control handle 16 that allows an operator to manipulate the catheter, including deflection of the intermediate section 14.

The elongate catheter body may be a relatively highly torsionable shaft with the distal tip section 13 attached to the deflectable intermediate section 19 and containing the electrode assembly 15 with an electrode array. For example, the distal tip section 13 may comprise a 3.5mm tip dome with three microelectrodes. All electrodes can be used for recording and stimulation purposes. The rocker 34 may be used to deflect the distal tip portion 13. The high torque shaft also allows the plane of the curved tip to be rotated to facilitate accurate positioning of the catheter tip at the desired site. Three curve type configurations named "D", "F" and "J" are available. The electrode assembly 15 is used to deliver ablation energy from the ablation generator 50 to a desired ablation site. The electrode assembly 15 and the ring electrode may be made of noble metal. In some examples, catheter 14 may also include six thermocouple temperature sensors embedded in 3.5mm tip electrode 15.

Fig. 3 is a schematic cross-sectional view of a chamber of the heart 12 showing a flexible deflectable intermediate section 19 of the catheter 14 inside the heart. Catheter 14 is typically inserted percutaneously through a blood vessel (such as the vena cava or aorta) into the heart and then inserted through the septum to reach the endocardial heart chamber. Electrode 15 on distal tip 28 of the catheter engages endocardial tissue 31. The pressure exerted by the distal tip on the endocardium locally deforms the endocardial tissue, such that the electrode 15 contacts the tissue over a relatively large area. In the illustrated example, the electrodes 15 engage the endocardium at an angle, rather than the frontal plane. Thus, the distal tip 28 bends at the resilient joint 33 relative to the deflectable intermediate section 19 of the catheter. Such bending facilitates optimal contact between the electrode and endocardial tissue.

The angle of curvature of the joint 33 is generally proportional to the pressure exerted by the tissue 30 on the distal tip 28 (or in other words, the pressure exerted by the distal tip on the tissue) due to the elastic mass of the joint. Thus, measurement of the bending angle gives an indication of the pressure. This pressure indication may be used by the operator of catheter 14 to ensure that the distal tip is pressed firmly enough against the endocardium to achieve the desired therapeutic or diagnostic result, but not so hard as to cause undesired tissue damage. One system for using pressure sensing catheters in this manner is described in U.S. patent nos. 8,357,152, 9,492,639, and 10,688,278, the disclosures of which are incorporated herein by reference. The catheter 14 may be used in such systems.

The ablation energy generator 50 may generate Radio Frequency (RF) current in accordance with known RF generators as disclosed in U.S. patent No. 5,906,614 and U.S. patent No. 10,869,713, the disclosures of which are incorporated herein by reference. The RF current forms the ablation focus through a thermal process. RF ablation increases tissue temperature and destroys cells by heating. In addition, the ablation energy generator 50 may also generate a Pulsed Field (PF) current to form an ablation focus using irreversible electroporation (IRE). IRE is primarily a nonthermal process that destroys cells by disrupting the cell membrane. A discussion of dual mode ablation energy generator 50 capable of generating RF signals and PF signals is found in U.S. publication No. 2021/0161592. U.S. publication No. 2021/0161592 also discusses the use of PF ablation and RF ablation in combination, and this patent is incorporated by reference, a copy of which is provided in the appendix.

The use of the ablation energy generator 50 and end-effector discussed above and below can be used to increase the method of foci formation using RF signals and PF signals. These ablation foci are formed in the patient's tissue and, in one example, are used in pulmonary vein isolation techniques.

Typical RF ablation forms a lesion depth in tissue of about 3mm to about 5mm. One example of a parameter for forming an RF ablation focus is setting the power of the RF signal to about 1 watt to about 400 watts. In addition, the RF signal is maintained for about 1 second to about 60 seconds.

Whereas RF ablation uses heat to damage tissue, RF signals typically produce temperature changes in the tissue of about 20 ℃ to about 70 ℃ above body temperature.

A typical PF differs from RF ablation in that at least the PF signal produces a temperature change of only a few degrees. The PF typically forms an ablation focus in patient tissue that is between about 4mm to about 6mm in size. To form an ablation focus, the voltage of the PF signal is set to about 800 volts to about 3000 volts. In addition, the PF signal is typically generated using a specific waveform.

However, one aspect of the present invention uses both the RF signal and the PF signal on the same portion of tissue to form a larger (i.e., deeper) lesion than either the RF signal or the PF signal alone can produce. Fig. 4A and 4B illustrate tissue treated with an example of the present invention. The light/white tissue is the RF ablation focus 402. In this example, the RF ablation focus is formed by generating an RF signal having a power of about 50W and a duration of about 10 seconds. The RF ablation signal forms an ablation focus having a specific depth 404. The PF signal is then applied to the same location on the tissue. The PF signal causes the formation of a PF ablation focus 406. This is shown by darker tissue surrounding the RF ablation focus 402. The PF signal is generated using a standard PF protocol as described in U.S. patent publication No. 2021/0161592.

Applying the PF signal to the same location as the RF signal is applied creates a combined ablation focus. The combined lesion depth 410 is formed by the RF lesion 402 and the PF lesion 406. The combined lesion depth or depth 410 is greater or deeper than the RF lesion depth 404 or PF lesion depth 408. The combined lesion depth 410 may be about 20% to about 40% greater than the RF lesion depth 404 and the PF lesion depth 408. One consideration for this surprising result is that the RF signal "activates" or "prepares" the non-ablated tissue surrounding the RF ablation region 402 so that the PF signal can enter the tissue deeper. Such activation may weaken the cells in the area below the area 402, so the PF ablation signal may form a deeper ablation focus 408. Conversely, first applying the PF signal destroys the voltage difference in the cell wall, so that the lesion can be as deep when the RF signal is applied. Both the PF signal and the RF signal may also be applied simultaneously to achieve substantially the same depth of the ablation focus. It should be noted here that for ease of measurement, the ablation focus "depth" (the maximum range measured from the electrode contact point to the depth inside the incised tissue) is measured to the maximum depth, but the average depth can also be used to quantify the ablation effect of each ablation modality.

To date, we have devised an ablation system for electrophysiological ablation that provides a combined ablation focus depth via two different energy modalities: (a) An Alternating Current (AC) signal generator configured to provide a radio frequency signal at high power; and (b) a Direct Current (DC) signal generator configured to provide a high voltage pulse. The system also includes a catheter having an end effector electrically coupled to the AC signal generator and the DC signal generator. The end effector can have at least one electrode disposed on the end effector such that the electrode delivers a high voltage pulse from the at least one electrode to organ tissue within a patient, to first and second return electrodes coupled to an exterior of the patient's body, and to one of the first or second return electrodes between the at least one electrode and one of the first or second return electrodes. The RF signal and the high voltage pulse may be applied to the organ tissue sequentially or simultaneously.

In an example, an end effector can have a cylindrical member with a distal tip electrode and irrigation ports disposed on the cylindrical member to provide irrigation fluid proximate the distal tip electrode.

Another example may have a distal tip electrode coupled to a force sensor. In addition, the radio frequency signal may be applied with a contact force of about 5 grams or more. In addition, the radio frequency signal may be provided with a power of at least 25 watts (up to 400 watts) at a frequency of about 350kHz to about 500 kHz. The radio frequency signal may also include a frequency of 350kHz to about 500kHz, and the radio frequency signal may be provided for a duration of at least 1 second to about 240 seconds.

For other examples, the high voltage pulse may include an amplitude of at least 800V to about 3000V. Further, the duration of each high voltage pulse may be less than 20 microseconds and provide a burst of about 100 microseconds. A time gap of any value selected from 0.3 ms to 1000 ms may be provided between adjacent bursts. These bursts may provide PF bursts. The PF burst may have any value between 2 bursts and 100 bursts, wherein the duration of the PF burst comprises any value selected from 0 milliseconds to 500 milliseconds. In addition, the high voltage pulse may provide about 60 joules or less.

Because of the systems and disclosure provided herein, we devised a method 500 of ablating tissue using the present invention, as shown in fig. 5. The method 500 may include positioning an electrode in contact with tissue (step 502). Once contacted, the method 500 may include applying a first ablation signal to tissue with an electrode (step 504). In one example, the first ablation signal may be an RF ablation signal. However, in other examples, the PF ablation signal may be the first ablation signal. The first ablation signal may form a first ablation focus including a first depth and may produce a first temperature change in tissue.

A second ablation signal may be applied to the tissue using the electrode to form a second ablation focus in the tissue (step 506). In an example, the second ablation signal may be different from the first ablation signal. The second ablation focus may be formed to have a second size. The second ablation signal may produce a second temperature change in the tissue that differs from the first temperature change by at least 10 ℃. As above, if the RF signal is a first signal, the PF signal may be a second signal, and when the PF signal is a first signal, the RF signal may be a second signal. In the case where RF ablation results in a tissue temperature change of greater than 20℃, the PF results in a temperature change of only a few degrees.

Alternatively, the first lesion may be formed with little or no first temperature change in the temperature of the tissue, and the second lesion may be formed by producing a second temperature change in the tissue that differs from the first temperature change by at least 10 ℃.

The method may include 500 forming a combined ablation focus (step 508), which may be caused by applying the first and second ablation signals. The deeper/larger combination ablation focus may be formed from a combination of a first ablation focus and a second ablation focus having a combined size. The combined depth may be about 20% to about 40% greater than either of the first depth and the second dimension. Further, the method 500 may include sequentially applying the first ablation signal and the second ablation signal. This may include first applying the RF signal and then applying the PF signal, or vice versa. However, whereas Alternating Current (AC) may be used to generate the RF signal and Direct Current (DC) may be used to generate the PF signal, another example may have both signals generated simultaneously or at least have some overlap in the application of the RF signal and the PF signal. In addition, the contact force between the tissue and the electrode is known to be one factor in the effectiveness of forming an ablation focus. In one example, the contact force may be about 5 grams to about 40 grams.

Although the present disclosure is described as being applicable to catheters 14 having tip electrodes 15 as shown and described with respect to fig. 2A-3, the disclosed techniques are not so limited and may be applicable to catheters having other configurations. For example, the disclosed techniques may be applicable to: basket catheter 600A (as shown in fig. 6A and described in U.S. provisional patent application No. 63/336,094, which provisional patent application is incorporated herein by reference); a circular catheter 600B having a circular region generally transverse to the longitudinal axis of the catheter (as shown in fig. 6B and described in U.S. provisional patent application No. 63/220,312, which is incorporated herein by reference); and a planar array catheter 600C having a planar array of electrodes (as shown in fig. 6C and described in U.S. patent publication No. 2021/0369338). Furthermore, the disclosed techniques may be applicable to catheters with or without the ability to deliver irrigation to the area proximate the electrode. Furthermore, the disclosed techniques may be applicable to catheters having force sensors configured to detect forces applied to the distal end of the catheter as well as catheters without force sensors. In other words, the disclosed techniques may be applicable to a series of catheters having electrodes configured to ablate tissue.

Fig. 6A is a perspective view of a basket catheter 600A having a basket electrode assembly 610 attached to the distal end of deflectable intermediate section 619. Basket electrode assembly 610 can include a plurality of ridges 622, where each ridge has one or more electrodes 626 attached thereto. The electrode 626 may be configured for mapping and/or ablation. For example, the electrode 626 may be configured to deliver RF energy or PF energy to ablate tissue in accordance with the techniques described herein. As will be appreciated, by using basket electrode assembly 610 to deliver RF energy or PF energy, the disclosed techniques may be configured to ablate a larger area of tissue than tip electrode 15 described with respect to fig. 2A-3. In some examples, selected electrodes 626 on basket electrode assembly 610 may be energized to ablate selected areas of tissue contacted by basket electrode assembly 610, enabling physician 24 to better control basket electrode assembly 610.

Fig. 6B is an illustration of a profile view of a circular catheter 600B having a circular region 630 attached to a deflectable intermediate section 619. The circular region 630 is disposed generally orthogonal to a longitudinal axis passing through the distal end of the deflectable intermediate section 619. The circular region 630 is preferably substantially perpendicular to the catheter body and forms a flat circle, or may be slightly helical, as shown in fig. 6B.

The circular region 630 includes electrodes 626 distributed around its circumference. The electrode 626 may be configured for mapping and/or ablation. During an exemplary treatment of electrode 626 for ablating tissue, electrode 626 may be configured to deliver RF energy and PF energy to ablate tissue in accordance with the techniques disclosed herein. When the diameter of the circular main region substantially corresponds to the diameter of a pulmonary vein or coronary sinus, the depth of the substantially circular region 630 may allow for ablation of tissue along the diameter of the pulmonary vein or other tubular structure of the heart 12 or in the vicinity of the heart. The circular arrangement of electrodes 626 facilitates the formation of a circular or annular ablation focus to interrupt electrical activity through the circumference of the tubular body structure, thereby electrically isolating the tubular structure from tissue on opposite sides of the annular ablation focus. In other examples, each electrode 626 may be energized individually to provide RF ablation or PF ablation only at selected portions of tissue.

Fig. 6C shows a planar array catheter 600C having a plurality of ridges 622 disposed in a plane and attached to the distal end of deflectable intermediate section 619. Each ridge 622 has one or more electrodes 626 disposed thereon. Each electrode 626 may be configured for mapping and/or ablation. For example, the electrode 626 may be configured to deliver RF energy or PF energy to ablate tissue in accordance with the techniques described herein. By arranging electrodes 626 in a planar array along ridge 622, planar array catheter 600C may be configured to facilitate ablating a larger area of tissue than tip electrode 15 described with respect to fig. 2A-3. In some examples, selected electrodes 626 on planar array catheter 600C may be energized to ablate selected areas of tissue contacted by electrodes 626, enabling physician 24 to better control planar array catheter 600C.

As will be appreciated, the method 500 described herein may vary according to the various elements and examples described herein. That is, a method according to the disclosed technology may include all or some of the steps described above, and/or may include additional steps not explicitly disclosed above. Some steps may be performed sequentially or simultaneously. Furthermore, methods according to the disclosed technology may include some, but not all, of the specific steps described above. Furthermore, the various methods described herein may be combined in whole or in part.

While the present disclosure has been described in connection with the various exemplary aspects, as illustrated in the various figures and described above, it is to be understood that other similar aspects may be used or modifications and additions may be made to the described aspects for performing the same function of the present disclosure without deviating therefrom. For example, in various aspects of the present disclosure, methods and compositions are described in accordance with various aspects of the presently disclosed subject matter. Other methods or components equivalent to these described aspects are also contemplated by the teachings herein. Accordingly, the disclosure should not be limited to any single aspect, but rather construed in breadth and scope in accordance with the appended claims.

Claims

1. A method of ablating tissue, comprising:

positioning an electrode in contact with the tissue;

Applying a first ablation signal to the tissue with the electrode, comprising:

Forming a first ablation focus comprising a first depth, wherein the temperature of the tissue has little or no first temperature change; and

Applying a second ablation signal to the tissue, different from the first ablation signal, with the electrode, comprising:

Forming a second ablation focus comprising a second size; and

Generating a second temperature change in the tissue, the second temperature change differing from the first temperature change by at least 10 ℃; and

Forming a combination ablation site comprising the first and second ablation sites and comprising a combination size,

The combined depth is about 20% to about 40% greater than either of the first depth and the second dimension.

2. The method of claim 1, wherein the first and second ablation signals are applied to the tissue in at least one of a sequential or simultaneous manner.

3. The method of claim 1, wherein the positioning step comprises applying a contact force between the tissue and the electrode of about 5 grams to about 40 grams.

4. The method of claim 1, wherein the first ablation signal is one of a Radio Frequency (RF) signal or a Pulsed Field (PF) signal and the second ablation signal is the other of the RF signal or the PF signal.

5. The method of any one of claims 1 to 4, further comprising:

Setting the power of the RF signal to about 1 watt to about 400 watts;

maintaining the RF signal for about 1 second to about 60 seconds; and

One of the first temperature change or the second temperature change is produced at about 20 ℃ to about 70 ℃.

6. The method of claim 4, further comprising:

the voltage of the PF signal is set to about 900 volts to about 3000 volts.

7. The method of any of claims 1-4, wherein the RF signal forms one of the first depth or the second depth between about 3mm to about 5mm.

8. The method of any of claims 1-4, wherein the PF signal forms one of the first depth or the second depth between about 4mm to about 6 mm.