Systems and methods for energy delivery

Abstract

A catheter assembly is provided. The catheter assembly comprises a catheter having at least one injury generating electrode, the at least one injury generating electrode configured to be placed in a patient, and at least one return array configured to be placed in a patient and at a distance from the at least one injury generating electrode, the at least one return array having at least one return electrode, and the catheter assembly is configured to generate injury in the vicinity of the at least one injury generating electrode by applying energy between i) the at least one injury generating electrode and ii) a return patch and at least one return electrode.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 457,252, filed on April 5, 2023, U.S. Provisional Patent Application No. 63 / 534,958, filed on August 28, 2023, and U.S. Provisional Patent Application No. 63 / 534,965, filed on August 28, 2023, all of which are hereby incorporated by reference in their entirety.

[0002] The present disclosure generally relates to tissue ablation systems. In particular, the present disclosure relates to systems for reducing the mobilization of skeletal muscle.

Background Art

[0003] It is generally known that ablation therapy can be used to treat various conditions that afflict the anatomical structures of the human body. For example, ablation therapy can be used to treat atrial arrhythmias. When tissue is ablated or at least exposed to ablation energy generated by an ablation generator and delivered by an ablation catheter, a lesion is formed in the tissue. Electrodes attached to or included in an ablation catheter are used to cause cell death (e.g., via apoptosis or necrosis of the tissue) in cardiac tissue in order to improve pathological conditions such as atrial arrhythmias (including, but not limited to, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter).

[0004] Arrhythmias (i.e., irregular heart rhythms) can lead to a variety of dangerous conditions, including loss of synchronized atrioventricular contractions and stagnation of blood flow, and can result in various illnesses and even death. The main cause of atrial arrhythmias is thought to be stray electrical signals within the left or right atrium of the heart. Ablation catheters deliver ablation energy (such as radiofrequency energy, cryoablation, lasers, chemicals, or high-intensity focused ultrasound) to cardiac tissue, causing damage to the tissue. This damage disrupts unwanted electrical pathways, thereby limiting or preventing stray electrical signals that lead to arrhythmias.

[0005] Electroporation is a non-thermal ablation technique that involves applying a strong electric field to induce pore formation in the cell membrane. The electric field can be induced by applying pulses with relatively short durations, for example, from nanoseconds to milliseconds. Such pulses can also be repeated to form a pulse train. When such an electric field is applied to tissue in vivo, cells within the tissue receive a transmembrane potential, causing pores in the cell wall to open. Electroporation can be reversible (i.e., the temporarily opened pores close again) or irreversible (i.e., the pores remain open). For example, in the field of gene therapy, reversible electroporation (i.e., temporarily opening pores) is used to introduce high molecular weight therapeutic vectors into cells. In other therapeutic applications, a properly configured pulse train alone can be used to induce cell destruction, for example, by causing irreversible electroporation.

[0006] Irreversible electroporation, also known as pulsed-field ablation (PFA), is a new technique with potential advantages over other types of ablation. The mechanism of damage formation in PFA involves the function of electric field exposure, which disrupts cell membrane permeability and leads to cell death. PFA uses (most common) bipolar and biphasic high-voltage and ultrashort-duration pulses to destabilize the cell membrane (creating pores in the cytoplasmic membrane) and induce cell death. This method has several potential advantages for ablation of cardiac arrhythmias, including high selectivity for myocardial tissue and minimal thermal effects.

[0007] At least some known PFA systems are single-catheter PFA systems. These include unipolar catheters that deliver energy from the catheter to a single back patch, and bipolar catheters that deliver energy between electrodes contained within the same catheter. At least some applications of unipolar catheters may, in some situations, involve significant skeletal muscle recruitment. At least some applications of bipolar catheters may minimize or eliminate skeletal muscle recruitment, but in some situations it may be difficult to achieve the same depth of injury as with unipolar catheters, and in some situations it may result in bubble formation.

[0008] Therefore, it is desirable to provide a catheter system that combines the advantages of unipolar and bipolar catheters while avoiding their potential drawbacks. [Overview of the Initiative] [Means for solving the problem]

[0009] In one embodiment, a catheter assembly is provided. The catheter assembly comprises a catheter having at least one injury generating electrode, the catheter having at least one injury generating electrode configured to be placed in a patient, and at least one return array being placed in a patient and located away from the at least one injury generating electrode, the at least one return array having at least one return electrode, and the catheter assembly is configured to generate injury in the vicinity of the at least one injury generating electrode by applying energy between i) the at least one injury generating electrode and ii) a return patch and at least one return electrode.

[0010] In another embodiment, an ablation system is provided. The ablation system comprises a generator and a catheter assembly coupled to the generator. The catheter assembly comprises a catheter having at least one injury generating electrode, the at least one injury generating electrode configured to be placed in a patient, and at least one return array configured to be placed in a patient and located away from the at least one injury generating electrode, the at least one return array having at least one return electrode, the generator being configured to generate injury in the vicinity of the at least one injury generating electrode by applying energy between i) the at least one injury generating electrode and ii) a return patch and the at least one return electrode.

[0011] In yet another embodiment, an ablation system is provided. The ablation system comprises a generator, a catheter having at least one injury generating electrode, the at least one injury generating electrode configured to be placed inside the patient, and a plurality of return patches configured to be placed outside the patient, wherein the generator is configured to apply energy between the at least one injury generating electrode and the plurality of return patches to generate injury in the vicinity of the at least one injury generating electrode.

[0012] In yet another embodiment, an ablation system is provided, comprising a generator and a plurality of electrodes coupled to the generator, wherein the ablation system is configured to apply energy between a first electrode and a first subset of the plurality of electrodes to generate a first injury near the first electrode, and then to apply energy between a second electrode and a second subset of the plurality of electrodes to generate a second injury near the second electrode, wherein the first and second injuries overlap at least partially.

[0013] The above and other aspects, features, details, usefulness and advantages of this disclosure will become apparent from reading the following description and claims, as well as from examining the accompanying drawings. [Brief explanation of the drawing]

[0014] [Figure 1] Schematic and block diagram of a system for electroporation therapy.

[0015] [Figure 2] A simplified schematic diagram of one embodiment of a catheter assembly for use with an ablation system.

[0016] [Figure 3] A simplified schematic diagram of another embodiment of a catheter assembly for use with ablation.

[0017] [Figure 4] Simplified schematic diagram of one embodiment of the return array.

[0018] [Figure 5] Simplified schematic diagram of another embodiment of the return array.

[0019] [Figure 6] Simplified schematic diagram of another embodiment of the return array.

[0020] [Figure 7A] Simplified schematic diagram of one embodiment of the return array assembly.

[0021] [Figure 7B] Simplified schematic diagram of the return array assembly shown in FIG. 7A slid onto an introducer used to deploy the damage generating catheter.

[0022] [Figure 8] Schematic diagram of one embodiment of patch placement.

MODE FOR CARRYING OUT THE INVENTION

[0023] A system and method for a catheter assembly are provided. The catheter assembly comprises a catheter having at least one injury generating electrode, the at least one injury generating electrode configured to be placed in a patient, and at least one return array, the at least one return array having at least one return electrode, the catheter assembly being configured to apply energy between i) at least one injury generating electrode and ii) a return patch and at least one return electrode to generate injury in the vicinity of the at least one injury generating electrode.

[0024] While at least some embodiments of this disclosure are described in relation to pulmonary vein isolation (PVI), the features and methods described herein are intended to be incorporated into any number of systems and any number of applications, as will be understood by those skilled in the art based on this disclosure.

[0025] Furthermore, while at least some embodiments of this disclosure describe electroporation applications in which an electric field is applied between electrodes, the features and methods described are intended to be applicable to other energy delivery applications. For example, in some embodiments, the features and methods described herein are used in radio frequency (RF) applications in which electrical energy is used to thermally ablate tissue.

[0026] Figure 1 is a block diagram of system 10 for electroporation therapy. Generally, system 10 comprises a catheter electrode assembly 12 positioned at the distal end 48 of a catheter 14. As used herein, “proximal” refers to the direction toward the end of the catheter closer to the clinician, and “distal” refers to the direction toward away from the clinician and (generally) into the patient’s body. The electrode assembly includes one or more electrically insulated individual electrode elements. Each electrode element, also referred to herein as a catheter electrode, is individually wired to function as a bipolar or multipolar electrode, either selectively paired with or combined with other electrode elements.

[0027] System 10 may be used for pulsed-field ablation (PFA) (also known as irreversible electroporation (IRE)) to destroy tissue. In particular, System 10 may be used for electroporation-induced primary apoptosis therapy, which refers to the effect of delivering an electric current in such a way that it directly causes the irreversible loss of the cell membrane (cell wall), leading to its destruction and cell apoptosis. This mechanism of cell death can be considered an "outside-in" process, meaning that the destruction of the cell's outer wall has a detrimental effect on the inside of the cell. Typically, in classical cell membrane electroporation, the current is delivered as a pulsed electric field in the form of short-duration pulses (e.g., having a duration of 0.1 to 20 milliseconds (ms)) between closely spaced electrodes, capable of delivering an electric field strength of about 0.1 to 1.0 kilovolts / centimeter (kV / cm). System 10 may be used, for example, for high-power (e.g., high voltage and / or high current) PFA treatments. In some specific embodiments, System 10 is configured to deliver a PFA signal with a relatively high voltage and a low pulse duration.

[0028] In one embodiment, all electrodes of the catheter deliver current simultaneously. Alternatively, in another embodiment, stimulation is delivered between pairs of electrodes on the catheter. Using multiple electrodes to deliver current simultaneously may facilitate the formation of sufficiently deep wounds for electroporation. To facilitate switching between i) simultaneously activating electrodes to deliver energy and ii) activating electrodes to sense signals (e.g., independently of each other), electrodes may be switchable between being connected to a 3D mapping system and being connected to an EP amplifier.

[0029] While the energizing strategy is described as including DC pulses, embodiments may use variations, and it should be understood that these remain within the spirit and scope of this disclosure. For example, exponentially decaying pulses, exponentially increasing pulses, and combinations thereof may be used. Furthermore, in some embodiments, AC pulses may be used. Also, as described above, in some embodiments, RF energy delivery may be used.

[0030] Furthermore, it should be understood that the mechanism of cell destruction in PFA is not primarily due to the heating effect, but rather to cell membrane destruction caused by the application of a high-voltage electric field. Therefore, PFA makes it easier to reduce the thermal effect of ablation. This "cold therapy" thus possesses desirable characteristics. However, as mentioned above, the systems and methods described herein may also be used for RF applications.

[0031] With this background, referring again to Figure 1, the system 10 comprises a catheter electrode assembly 12 including at least one catheter electrode. The electrode assembly 12 is incorporated as part of a medical device such as a catheter 14 for PFA therapy of tissue 16 in the patient's body 17. In exemplary embodiments, the tissue 16 includes cardiac or myocardial tissue. However, it should be understood that embodiments may be used to perform PFA therapy with respect to various other body tissues.

[0032] Figure 1 further illustrates a plurality of return electrodes designated 18, 20, and 21, which may be used by various subsystems included in the overall system 10, such as an electroporation generator 26, an electrophysiological (EP) monitor such as an ECG monitor 28, and a localization and navigation system 30 for visualization, mapping, and navigation of internal structures. In the illustrated embodiment, the return electrodes 18, 20, and 21 are patch electrodes. The illustration of a single patch electrode is illustrative (for clarity), and it should be understood that such subsystems to which these patch electrodes are connected may include, and typically will include, a plurality of patch (body surface) electrodes. Furthermore, the patches may be placed in any suitable location. For example, one or more patches may be placed on the lower back of the patient, centered relative to the patient's spine.

[0033] In other embodiments, the return electrodes 18, 20, and 21 may be other types of electrodes suitable for use as return electrodes, for example, including one or more catheter electrodes. The return electrodes, which are catheter electrodes, may be part of the electrode assembly 12 or part of a separate catheter or device (not shown). The system 10 may further include a main computer system 32 (including an electronic control unit 50 and a data storage memory 52), which in certain embodiments may be integrated with a localization and navigation system 30. The system 32 may further include, among other components, conventional interface components such as various user input / output mechanisms 34A and a display 34B.

[0034] The electroporation generator 26 is configured to energize the electrode elements according to a PFA energizing strategy, which may be predetermined or user-selectable. For primary apoptosis therapy induced by PFA, the generator 26 may be configured to generate a current that is delivered through the electrode assembly 12 as a pulsed electric field in the form of short-duration DC pulses (e.g., durations of nanoseconds to several milliseconds, durations of 0.1 to 20 milliseconds, or any duration suitable for electroporation) between closely spaced electrodes, capable of delivering an electric field strength of approximately 0.1 to 1.0 kV / cm (i.e., at the tissue site). The amplitude and pulse duration required for PFA are inversely proportional. As the pulse duration decreases, the amplitude must be increased to achieve PFA.

[0035] PFA has been shown to be an effective form of ablation for the treatment of cardiac arrhythmias, particularly instantaneous pulmonary vein isolation (PVI). PFA involves delivering high-voltage pulses from electrodes placed on a catheter (e.g., including the basket catheter and / or balloon catheter described herein). In PFA, for example, the voltage amplitude may range from about 300V to at least 3,200V (or even on the order of 10,000V), and the pulse width may range from several hundred nanoseconds to several tens of milliseconds.

[0036] These electric fields may be applied between adjacent electrodes (bipolar approach) or between one or more electrodes and the return patch (unipolar approach). Each of these approaches has its own advantages and disadvantages.

[0037] For example, regarding the continuity of damage, a unipolar approach may leave a gap in the damage area (called a dead zone) between electrodes where the electric field strength is low or zero, whereas a bipolar approach, due to the high electric field strength, can generally prevent dead zones between electrodes.

[0038] Regarding the size and proximity of the injury, the unipolar approach has a wider effective range and may be able to create deeper injuries with the same applied voltage. Furthermore, the unipolar approach can create injuries at a distance (e.g., generally close but not necessarily in contact with tissue). The bipolar approach can create smaller injuries and requires proximity or contact with tissue to create percutaneous injuries. However, while the unipolar approach may create injuries that are larger than necessary, injuries produced using the bipolar approach may be more localized.

[0039] Due to their broad effective range, unipolar approaches may cause unwanted activation of skeletal muscle and / or nerves. In contrast, bipolar approaches have a limited effective range proportional to the electrode spacing on the leads and are less likely to depolarize cardiomyocytes or nerve fibers.

[0040] In a unipolar approach, only a single potential is applied to the catheter wire and electrodes. Furthermore, because all electrodes have the same polarity, this configuration is less susceptible to arc discharge (for example, when using the basket catheter and / or balloon catheter described herein). In contrast, in a bipolar approach, because different electrodes are at different potentials, the internal structure of the catheter must be constructed to prevent arc discharge.

[0041] Since both unipolar and bipolar approaches have their advantages and disadvantages, it would be desirable to provide a PFA system that achieves the advantages of both approaches while avoiding the disadvantages of both.

[0042] Returning to Figure 1, the electroporation generator 26, sometimes referred to herein as the DC energy source, is a monophase electroporation generator 26 configured to generate a series of DC energy pulses, all generating current in the same direction. In other embodiments, the electroporation generator is a biphase or polyphase electroporation generator configured to generate DC energy pulses, all not generating current in the same direction. In some embodiments, the electroporation generator 26 is configured to output energy in DC pulses at selectable energy levels such as 50 joules, 100 joules, or 200 joules. Other embodiments may have more or fewer energy settings, and the available settings may be the same or different. To successfully perform electroporation, some embodiments utilize an output level of 200 joules. For example, the electroporation generator 26 may output DC pulses with a peak magnitude ranging from about 300 volts (V) to about 3,200 V at an output level of 200 joules. In some embodiments, the peak magnitude may be even larger (e.g., on the order of 10,000 V). In other embodiments, any other suitable positive or negative voltage may be output. For example, in some embodiments, the systems and methods described herein may include pulses having a pulse width of about 200 nanoseconds to about 20 microseconds and an amplitude of about 500 V to about 4,000 V.

[0043] In some embodiments, the variable impedance 27 can be used to change the impedance of the system 10 to limit arc discharge. Furthermore, the variable impedance 27 may be used to change one or more characteristics of the output of the electroporation generator 26, such as amplitude, duration, or pulse shape. Although illustrated as a separate component, the variable impedance 27 may be incorporated into the catheter 14 or the generator 26.

[0044] In other embodiments, one or more semiconductor devices may be used in series with the catheter 14 to limit arc discharge. For example, a semiconductor device could be implemented that is a specially designed two-terminal device adapted from a field-effect transistor, capable of acting very quickly to limit current and power. Two of these devices may be used for biphasic energy delivery and one for monophasic energy delivery. While commercially available devices are designed for low currents and are typically in the milliampere range, semiconductor devices used for PFA applications may also be adapted by changing the size and / or dopant concentration of existing devices. This would facilitate improved patient safety and potentially allow for multiple uses of the catheter and generator.

[0045] In the illustrated embodiment, the catheter 14 comprises a cable connector or interface 40, a handle 42, and a shaft 44 having a proximal end 46 and a distal end 48. The catheter 14 may also comprise other conventional components not shown herein, such as a temperature sensor, additional electrodes, and corresponding conductors or lead wires. The connector 40 provides mechanical and electrical connections for a cable 56 extending from the generator 26. The connector 40 may comprise conventional components known in the art and is located at the proximal end of the catheter 14, as shown.

[0046] The handle 42 may provide a place for the clinician to hold the catheter 14 and may further provide means for manipulating or guiding the shaft 44 within the body 17. For example, the handle 42 may include means for changing the length of a guidewire extending through the catheter 14 to the distal end 48 of the shaft 44, or means for manipulating the shaft 44. Furthermore, in some embodiments, the handle 42 may be configured to change the shape, size, and / or orientation of a portion of the catheter, and it will be understood that the structure of the handle 42 may vary. In another embodiment, the catheter 14 may be robot-driven or robot-controlled. Thus, the catheter 14 is manipulated using a robot rather than the clinician manipulating the handle to move the catheter 14 forward / backward and / or manipulate or guide it. The shaft 44 is an elongated tubular flexible member configured to move within the body 17. The shaft 44 supports the electrode assembly 12 and is configured to include associated conductors and, optionally, additional electronics used for signal processing or adjustment. The shaft 44 may also allow for the transport, delivery, and / or removal of fluids (including irrigation fluids and body fluids), pharmaceuticals, and / or surgical instruments or tools. The shaft 44 may be made of a conventional material such as polyurethane and define one or more lumens configured to accommodate and / or transport electrical conductors, fluids, or surgical instruments, as described herein. The shaft 44 may be introduced into a blood vessel or other structure within the body 17 via a conventional introducer. The shaft 44 may then advance / retract and / or be manipulated or guided through the body 17 to a desired location, such as a site of tissue 16, including the use of a guidewire or other means known in the art.

[0047] In some embodiments, the catheter 14 includes a basket catheter assembly having a catheter electrode (not shown in Figure 1) positioned at the distal end of a shaft 44 within the basket structure. Furthermore, as described herein, an inflatable balloon may be housed within the basket structure.

[0048] The localization and navigation system 30 may be provided for visualization, mapping, and navigation of internal structures. The localization and navigation system 30 is a conventional device commonly known in the art (for example, generally described in U.S. Patent Application Publication 2020 / 0138334, entitled “Method for Medical Device Localization Based on Magnetic and Impedance Sensors,” EnSite X TMThis may include mapping systems (the entire disclosure thereof is incorporated herein by reference). However, it should be understood that this system is illustrative and not inherently limiting. Other techniques for the spatial positioning / navigation (and visualization) of catheters are also known, such as Biosense-Webster's CARTO navigation and positioning system, Boston Scientific SyMed's Rhythmia® system, Koninklijke Philips NV's KODEX® system, Northern Digital's AURORA® system, commonly available fluoroscopy systems, or magnetic positioning systems such as Mediguide's gMPS system. In this regard, some positioning, navigation and / or visualization systems may include sensors for generating signals indicating the position of a catheter, for example, one or more electrodes in the case of an impedance-based positioning system, or one or more coils (i.e., wire windings) configured to detect one or more characteristics of a magnetic field in the case of a magnetic field-based positioning system. As yet another example, system 10 may utilize a combination of electric field-based and magnetic field-based systems, such as those commonly shown with reference to U.S. Patent No. 7,536,218, whose entire disclosure is incorporated herein by reference, entitled "Hybrid Magnetic-Based and Impedance Based Position Sensing."

[0049] To monitor the operation of system 10, one or more impedances between the catheter electrodes and / or return electrodes 18, 20, and 21 may be measured. For example, for system 10, impedances may be measured as described in U.S. Patent Application Publication No. 2019 / 0117113 filed on 23 October 2018, U.S. Patent Application Publication No. 2019 / 0183378 filed on 19 December 2018, and U.S. Patent Application No. 63 / 027,660 filed on 20 May 2020, all of which are incorporated herein by reference in their entirety.

[0050] The systems and methods described herein include return electrode arrangements that facilitate the realization of the advantages of both unipolar and bipolar approaches to PFA. In some embodiments, as described herein, the PFA system comprises a lesion target array and at least one return electrode array. The at least one return electrode array is located remotely from the lesion target array but is located within the patient, similar to the lesion target array. In other embodiments, the PFA system comprises a lesion target array and a plurality of return patches distributed on the patient's surface, as described herein. These embodiments facilitate the reduction of skeletal muscle recruitment by distributing the current using the return electrode arrangements described herein.

[0051] As described herein, a damaged area target array comprises one or more damage generating electrodes. Therefore, in some embodiments, the damaged area target array comprises multiple damage generating electrodes. In such embodiments, the multiple damage generating electrodes may be operated together (e.g., in a "ganged" configuration) to function as a single larger effective electrode. While individual damage generating electrodes may generate spot-like damage or relatively circular damage, operating multiple damage generating electrodes together can generate damage of other desired shapes (e.g., linear damage, relatively large circular damage, elliptical damage, etc.). Those skilled in the art will understand that many different damage shapes are possible using the embodiments described herein.

[0052] Furthermore, although some of the embodiments disclosed herein are described in the context of ring electrodes, those skilled in the art will understand that the systems and methods described herein may be carried out using any suitable type of electrode. For example, the damage generating electrode and return electrode may include ring electrodes, relatively small spot electrodes (e.g., arrays of flexible printed electrodes), dome-shaped or rounded electrodes, stud or spline electrodes, and / or any other suitable type of electrode.

[0053] Figure 2 is a simplified schematic diagram of one embodiment of a catheter assembly 200 for use with an ablation system (e.g., system 10 (shown in Figure 1)). The catheter assembly 200 comprises a first catheter 202 and a second catheter 204. The distal end 206 of the first catheter 202 is positioned at a patient injury target location 208 (i.e., the region where the tissue to be ablated is located) and comprises at least one injury generating electrode 210. In this embodiment, the second catheter 204 comprises a first return array 220 located at the distal end 221 of the second catheter 204 and a second return array 222 proximal to the first return array 220. The first return array 220 is positioned at a first return position 224, and the second return array 222 is positioned at a second return position 226. The first return position 224 and the second return position 226 may be, for example, in the patient's blood flow.

[0054] The first return array 220 and the second return array 222 each include at least one return electrode 230. In Figure 2, each return array 220 and 222 includes three return electrodes 230. Alternatively, each return array 220 and 222 may include any appropriate number of electrodes 230. For example, in one embodiment, each return array 220 and 222 includes 10 return electrodes 230.

[0055] During operation, PFA is achieved by applying an electric field between at least one injury-generating electrode 210 of the first catheter 202 and the return electrode 230 of the second catheter 204. Notably, the first return array 220 and the second return array 222 have a much larger electrode surface area than at least one injury-generating electrode 210. For example, the first return array 220 and the second return array 222 may have lengths ranging from approximately 150 millimeters (mm) to 305 mm. Therefore, when an electric field is applied, the current density of the first return array 220 and the second return array 222 is much lower than the current density of at least one injury-generating electrode 210. As a result, injury is generally generated at at least one injury-generating electrode 210, but not at the first return array 220 and the second return array 222.

[0056] This configuration allows for the use of a larger electric field to more effectively, deeply, and significantly increase the size of the injury target at the injury site 208, while avoiding undesirable effects at the first return position 224 and the second return position 226, such as undesirable heating, injury formation, and / or smooth muscle reaction. This configuration also facilitates making the first catheter 202 angle-agnostic for injury purposes (i.e., the resulting injury shape does not substantially change even if the orientation angle between at least one injury-generating electrode 210 and the tissue being ablated differs).

[0057] For example, in one experimental scenario, each of the first return array 220 and the second return array 222 had 10 return electrodes 230. In this scenario, when an electric field was generated between at least one damage-generating electrode 210 and both the return arrays 220 and 222 (i.e., between at least one damage-generating electrode 210 and a total of 20 return electrodes 230), no damage was formed at the first return position 224 and the second return position 226. When an electric field was generated between at least one damage-generating electrode 210 and only one of the return arrays 220 and 222 (i.e., between at least one damage-generating electrode 210 and a total of 10 return electrodes 230), only surface damage was formed at the relevant one of the first return position 224 and the second return position 226.

[0058] Figure 3 is a simplified schematic diagram of another embodiment of a catheter assembly 300 for use with an ablation system (e.g., system 10 (shown in Figure 1)). The catheter assembly 300 comprises a first catheter 302 and a second catheter 304. The distal end 306 of the first catheter 302 is positioned at the patient's injury target location 308 (i.e., the area where the tissue to be ablated is located) and comprises at least one injury generating electrode 310. In this embodiment, the second catheter 304 comprises a return array 320 located at the distal end 322 of the second catheter 304. The first return array 320 comprises at least one return electrode 330.

[0059] In this embodiment, the first catheter 302 is positioned, for example, in the patient's left atrium and can roam freely with at least one injury-generating electrode 310 to generate injury as desired.

[0060] The second catheter 304 is positioned in the patient's coronary sinus. Alternatively, the second catheter 304 may be positioned, for example, in the patient's inferior vena cava, right atrium, or pericardium. This positioning of the second catheter 304 ensures that the return array 320 is close to tissue that is less affected by the applied PFA energy. Alternatively, or additionally, the second catheter 304 may include structural features (detailed below) that physically prevent at least one return electrode 330 from getting close enough to cardiac tissue to form damage.

[0061] During operation, PFA is achieved by applying an electric field between at least one injury-generating electrode 310 of the first catheter 302 and at least one return electrode 330 of the second catheter 304. Notably, the return array 320 has a much larger electrode surface area than the at least one injury-generating electrode 310. Therefore, when an electric field is applied, the current density of the return array 320 is much lower than that of the at least one injury-generating electrode 310. As a result, injury is generated at the at least one injury-generating electrode 310, but not at the return array 320.

[0062] By positioning at least one return electrode 330 away from at least one damage-generating electrode 310, the depth and magnitude of the generated damage can be easily adjusted by changing the voltage of the applied electric field. Specifically, this arrangement can significantly increase the damage depth achievable with a single voltage (allowing the use of lower voltages) and may also reduce microbubble formation.

[0063] The embodiments shown in Figures 2 and 3 illustrate two catheters (for example, one catheter having an electrode for wound formation and another catheter including one or more return arrays), but those skilled in the art will understand that other embodiments are possible. For example, in one embodiment, a single catheter is used, and one or more return arrays are positioned sufficiently distal to the wound formation electrode. In another example, three catheters are used, with the first catheter including the wound formation electrode, the second catheter including the first return array, and the third catheter including the second return array.

[0064] Furthermore, in embodiments described herein, energy may be delivered between at least one injury-generating electrode (e.g., injury-generating electrode 210 and injury-generating electrode 310) and a combination of i) one or more external patch electrodes (e.g., return electrodes 18, 20, 21) and ii) one or more internal return electrodes (e.g., electrodes of return arrays 220, 222, and 322). That is, the energy delivered from at least one injury-generating electrode is distributed between i) one or more external return electrodes and ii) one or more internal electrodes. This concentrates the energy on at least one injury-generating electrode, generating injury in the vicinity of that electrode, while dissipating the current between multiple returns (e.g., patches and internal electrodes) to prevent injury from being generated at the returns. It should be noted that the internal electrodes may be located on the same catheter as at least one injury-generating electrode, or on one or more other catheters.

[0065] In one example, the injury-generating electrode is the tip electrode on the catheter, and a combination of i) one or more other electrodes on the same catheter and ii) one or more external patch electrodes functions as the return electrode.

[0066] In some embodiments, relatively large and continuous injuries may be generated by sequentially switching which electrode functions as the injury-generating electrode / return electrode. For example, consider a catheter including a proximal electrode, a distal electrode, and an intermediate electrode positioned between the proximal and distal electrodes. In the first stage, the proximal electrode is set as the injury-generating electrode, and the intermediate and distal electrodes are set as return electrodes (generating a first injury near the proximal electrode). In the second stage, the intermediate electrode is set as the injury-generating electrode, and the proximal and distal electrodes are set as return electrodes (generating a second injury near the intermediate electrode). In the third stage, the distal electrode is set as the injury-generating electrode, and the proximal and intermediate electrodes are set as return electrodes (generating a third injury near the distal electrode). This switching may be performed automatically using an appropriate control unit (e.g., a computer system 32).

[0067] If the proximal, intermediate, and distal electrodes are positioned at a sufficient distance from each other, the first, second, and third injuries will overlap at least partially, forming a larger single injury. It is noteworthy that this single injury may be formed with the catheter in a single position (i.e., it is not necessary to move the catheter between multiple different positions to form the injury).

[0068] In this embodiment, three electrodes are used on the same catheter, but those skilled in the art will understand that this method may also be applied using any appropriate number of electrodes on one or more catheters.

[0069] As described above, catheters comprising one or more return arrays may include structural features that physically prevent at least one return electrode from approaching cardiac tissue close enough to form damage. For example, Figure 4 is a simplified schematic diagram of one embodiment of a return array 400. The return array 400 comprises at least one return electrode 402 and a selectively inflatable balloon 404 surrounding the at least one return electrode 402. The balloon 404 is defined with a plurality of perfusion holes 406. Notably, the balloon 404 acts as a buffer or barrier, keeping at least one return electrode 402 at a distance from adjacent tissue, minimizing or eliminating the effect that at least one return electrode 402 has on that tissue when an electric field is applied.

[0070] Figure 5 is a simplified schematic diagram of another embodiment of the return array 500. The return array 500 comprises at least one return electrode 502 and a plurality of struts 504 surrounding the at least one return electrode 502 and forming a selectively expandable basket 506. The struts 504 are made of an insulating material, such as nitinol. Notably, the basket 506 acts as a buffer, keeping the at least one return electrode 502 at a distance from adjacent tissue, minimizing or eliminating the effect that the at least one return electrode 502 has on that tissue when an electric field is applied.

[0071] Figure 6 is a simplified schematic diagram of another embodiment of the return array 600. The return array 600 includes a wrap-around electrode 602 that spirally wraps multiple times around the catheter body 604, resulting in a relatively large electrode surface area (and reduced current density).

[0072] As those skilled in the art will understand, other return array configurations may be used to achieve a relatively large electrode surface area. For example, in some embodiments, the return array comprises a number of ring electrodes (e.g., five or more ring electrodes) that are activated together (e.g., in a “linked” configuration) to function as a larger effective electrode. Collectively, the number of ring electrodes form a relatively large electrode surface area (resulting in a reduced current density). In other embodiments, for example, a single elongated electrode and / or a rolled foil electrode may extend along a portion of the catheter body. Furthermore, in some embodiments, expandable features (e.g., expandable struts, expandable arms, and / or inflatable balloons) may be used to increase the effective electrode surface area.

[0073] In some embodiments, the return array may be mounted on a separate sleeve which may slide over or otherwise be coupled to the injury-generating catheter and / or introducer. For example, Figure 7A is a simplified schematic diagram of one embodiment of the return array assembly 700, and Figure 7B is a simplified schematic diagram of the return array assembly 700 which slides over an introducer 702 used to position the injury-generating catheter 704.

[0074] The return array assembly 700 comprises a sleeve 710 sized to slide on the introducer 702. The sleeve 710 comprises a return array 712 and an insulating portion 714. In this embodiment, the return array 712 is a single elongated electrode 716. However, other electrode configurations may be used (e.g., multiple ring electrodes, helically wound electrodes, coil electrodes, etc.). The return array assembly 700 further comprises an electrode connector 720 (e.g., for coupling the return array 712 to a pulse generator) and a flush port 722 (e.g., for facilitating the flushing of the return array 712 with fluid).

[0075] Figure 7B shows a return array assembly 700 coupled to an introducer 702. As shown in Figure 7B, the introducer 702 includes a handle 730 located distal to the return array assembly 700. A injury-generating catheter 704 extends distally from the introducer 702 through the vascular system 732, and the distal end 734 of the injury-generating catheter 704 is located within the left atrium 736. The distal end 734 includes at least one injury-generating electrode 738. In this embodiment, an elongated electrode 716 is located in the cardiac blood supply pool but not in the heart itself.

[0076] During operation, PFA is achieved by applying an electric field between at least one injury-generating electrode 738 and an elongated electrode 716. Notably, the elongated electrode 716 has a much larger electrode surface area than at least one injury-generating electrode 738. Therefore, when an electric field is applied, the current density at the elongated electrode 716 is much lower than the current density at at least one injury-generating electrode 738. As a result, injury is generated at at least one injury-generating electrode 738 (i.e., within the left atrium 736), but no injury is generated at the elongated electrode 716.

[0077] As described above, various embodiments of return arrays are possible, including those with relatively large electrode surface areas. In some embodiments, when a long array of return electrodes is used, higher resistance occurs at the distal end of the array, potentially resulting in the generation of shadow lesions at the distal end. To avoid this, the distal end electrodes of the array may be short-circuited with the other electrodes of the array. However, it is still desirable to have a certain degree of high resistance at the distal end. Therefore, resistive members may be used to facilitate the even distribution of current across the return array. For example, coil electrodes may be used, and the pitch of the coil electrodes may be set to achieve the desired resistance. Alternatively or additionally, a semi-resistive coating may be applied to one or more electrodes, the electrodes may be made of different materials (e.g., a more conductive material for more proximal electrodes and a more resistive material for more distal electrodes), the electrodes may have different surface areas, and / or the electrodes may have different shapes (e.g., holes and / or etching outs may be defined penetrating the more distal electrodes) to selectively change the resistivity of the electrodes so that the current is evenly distributed across the return array.

[0078] As described above, in some embodiments, PFA is achieved by applying a voltage between the injured target array and a plurality of return patches distributed on the patient's outer surface.

[0079] For example, Figure 8 is a schematic diagram of one embodiment of patch arrangement 800. Patch arrangement 800 comprises a first patch 802 on the patient's front 804, and a second patch 806 and a third patch 808 on the patient's back 810. As shown in Figure 8, the patches are positioned in the center of the patient's back 810 and front 804. Of course, those skilled in the art will understand that patch arrangement 800 is merely illustrative and other suitable configurations may be used.

[0080] Each of patches 802, 806, and 808 may be relatively large to achieve a more dispersed effect. Alternatively, two or more patches 802, 806, and 808 may be activated simultaneously to function as a larger active electrode to achieve a dispersed effect. Those skilled in the art will understand that patches 802, 806, and 808 may have any suitable size and shape. For example, the patches may be circular, rectangular, or square. Furthermore, the patches may have widths and heights between 2 and 7 inches (50.8 to 177.8 millimeters), respectively. As a result, the patch surface area may be between 4 and 49 square inches (25.8 to 316.1 cm²). 2 )

[0081] The distributed patch network reduces the total energy density in each patch 802, 806, and 808, facilitating the reduction of skeletal muscle recruitment during PFA therapy. In some embodiments, patches 802, 806, and 808 are activated iteratively. For example, in a first period, a voltage is applied between the injured target array (not shown) and the first patch 802; in a second period following the first, a voltage is applied between the injured target array and the second patch 806; and in a third period following the second, a voltage is applied between the injured target array and the third patch 808. By sequentially activating patches 802, 806, and 808, the total joules seen in each patch are reduced, the electrical impulses seen in each patch are reduced, and the overall current through the patch network is reduced, while distributing the voltage drop across patches 802, 806, and 808. This also facilitates the reduction of skeletal muscle recruitment. Of particular note is that by distributing the electric current across patches placed in various locations on the body, it becomes easier to suppress the patient's movements.

[0082] Those skilled in the art will understand that the various embodiments of the catheter assembly described herein can be implemented independently of each other or in any suitable combination.

[0083] Embodiments described herein provide a catheter assembly. The catheter assembly comprises a catheter having at least one injury generating electrode, the at least one injury generating electrode configured to be placed in a patient, and at least one return array configured to be placed in a patient and at a distance from the at least one injury generating electrode, the at least one return array having at least one return electrode, the catheter assembly is configured to generate injury in the vicinity of the at least one injury generating electrode by applying energy between i) the at least one injury generating electrode and ii) a return patch and the at least one return electrode.

[0084] While specific embodiments of this disclosure have been described above with some degree of detail, those skilled in the art will be able to make numerous modifications to the disclosed embodiments without departing from the spirit or scope of this disclosure. All directional references (e.g., top, bottom, upward, downward, left, right, leftward, rightward, top, bottom, upward, downward, vertical, horizontal, clockwise, and counterclockwise) are used solely for identification purposes to aid the reader's understanding of this disclosure and, in particular, do not create any limitation on the location, orientation, or use of this disclosure. References relating to connections (e.g., attached, joined, connected, etc.) should be interpreted broadly and may include intermediate members between the connection of elements and relative movement between elements. Thus, references relating to connections do not necessarily imply that two elements are directly connected and in a fixed relationship with one another. All matters included in the above description or shown in the accompanying drawings are intended to be interpreted only as illustrative and not limiting. Modifications of details or structures may be made without departing from the spirit of this disclosure as defined in the accompanying claims.

[0085] When describing elements of this disclosure or preferred embodiments thereof, the articles “a,” “an,” “the,” and “said” are intended to indicate the presence of one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be comprehensive and mean that additional elements other than those listed may exist.

[0086] Various modifications can be made to the above configuration without departing from the scope of this disclosure, so all matters included in the above description or shown in the accompanying drawings are intended to be interpretable, not restrictive.

Claims

1. A catheter assembly, A catheter comprising at least one injury-generating electrode, wherein the at least one injury-generating electrode is configured to be placed inside a patient, and the catheter and A return array comprising: at least one return array placed within the patient and configured to be located away from the at least one injury-generating electrode, wherein the at least one return array comprises at least one return electrode; The catheter assembly is configured to generate damage in the vicinity of the at least one damage generating electrode by applying energy between i) the at least one damage generating electrode and ii) a return patch and the at least one return electrode.

2. The catheter assembly according to claim 1, wherein the at least one return electrode has a larger electrode surface area than the at least one damage-generating electrode.

3. With at least one additional catheter, The catheter assembly according to claim 1, wherein the at least one additional catheter comprises the at least one return array.

4. The catheter assembly according to claim 1, wherein the at least one return array comprises a selectively inflatable balloon surrounding the at least one return electrode.

5. The catheter assembly according to claim 1, wherein the at least one return array comprises a plurality of insulating struts surrounding the at least one return electrode.

6. The catheter assembly according to claim 1, wherein the catheter assembly is configured to apply high-frequency energy in order to apply energy.

7. The catheter assembly according to claim 1, wherein the at least one return electrode comprises a wound electrode spirally wrapped around the catheter body.

8. The catheter assembly according to claim 1, wherein the at least one return electrode comprises a plurality of ring electrodes.

9. The catheter assembly according to claim 1, wherein the at least one return electrode comprises a single elongated electrode.

10. It further includes a sleeve configured to slide onto the introducer, The catheter assembly according to claim 1, wherein the sleeve comprises the at least one return array.

11. It is an ablation system, A generator, The system comprises a catheter assembly coupled to the generator, The catheter assembly is A catheter comprising at least one injury-generating electrode, wherein the at least one injury-generating electrode is configured to be placed inside a patient, and the catheter and A return array comprising: at least one return array placed within the patient and configured to be located away from the at least one injury-generating electrode, wherein the at least one return array comprises at least one return electrode; An ablation system in which the generator is configured to generate damage in the vicinity of the at least one damage generating electrode by applying energy between i) the at least one damage generating electrode and ii) the return patch and the at least one return electrode.

12. The ablation system according to claim 11, wherein the at least one return electrode has a larger electrode surface area than the at least one damage-generating electrode.

13. The catheter assembly further comprises at least one additional catheter, The ablation system according to claim 11, wherein the at least one additional catheter comprises the at least one return array.

14. The ablation system according to claim 11, wherein the at least one return array is configured to be positioned in the patient's bloodstream.

15. The ablation system according to claim 11, wherein the catheter assembly further comprises a resistive member configured to facilitate the even distribution of current across the at least one return array.

16. It is an ablation system, A generator, A catheter comprising at least one injury-generating electrode, wherein the at least one injury-generating electrode is configured to be placed inside a patient, and the catheter and The system comprises a plurality of return patches configured to be positioned outside the patient, An ablation system in which the generator is configured to apply energy between the at least one damage generating electrode and the plurality of return patches to generate damage in the vicinity of the at least one damage generating electrode.

17. The ablation system according to claim 16, wherein at least two of the plurality of return patches are configured to be activated simultaneously to function as a larger effective electrode.

18. The ablation system according to claim 16, wherein at least two of the plurality of return patches are configured to be activated repeatedly.

19. Each of the aforementioned patches is 4 square inches (25.8 cm) 2 The ablation system according to claim 16, having a larger surface area than ).

20. The ablation system according to claim 16, comprising a first patch configured to be positioned on the front of the patient, and second and third patches configured to be positioned on the back of the patient.

21. It is an ablation system, A generator, The generator comprises a plurality of electrodes coupled to it, The ablation system described above is Energy is applied between a first electrode among the plurality of electrodes and a first subset of the plurality of electrodes to generate a first damage near the first electrode. Subsequently, energy is applied between the second electrode among the plurality of electrodes and the second subset among the plurality of electrodes to generate a second damage in the vicinity of the second electrode. An ablation system in which the first injury and the second injury overlap at least partially.

22. The ablation system further comprises a catheter, The ablation system according to claim 21, wherein the catheter comprises the plurality of electrodes.

23. The ablation system according to claim 21, wherein at least one of the plurality of electrodes is placed on a catheter different from at least one of the other electrodes.

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