Pulsed field ablation device and method

Abstract

An ablation device and method for pulsed field ablation includes a catheter including an expandable basket, a set of electrodes formed on the expandable basket, and a pulse generator adapted to generate electrical pulses, the pulse generator being in electrical communication with the set of electrodes. The expandable basket is formed of a braided mesh of filaments, the filaments being made of a non-conductive material, at least a portion of the filaments having a lumen, the lumen including a fusible material, and the filaments further including an electrode and a conductive wire. The conductive wire extends at least partially through the lumen of the filament and is electrically connected to the electrode.

Description

[Technical Field]

[0001] The present invention relates to ablation devices and methods, and in particular to devices and methods for pulsed field ablation of target tissue by pulsed electric fields, where one of the main principles of ablation can be irreversible electroporation of cell membranes. [Background technology]

[0002] Atrial fibrillation is the most common sustained cardiac arrhythmia, affecting 10% of the population over the age of 60. In addition to pharmacological treatment, an established treatment to improve the symptoms of the disease and reduce mortality is the so-called catheter ablation.

[0003] Catheter ablation typically involves subcutaneously advancing one or more flexible catheters into a patient's blood vessels, either in the femoral, internal jugular, or subclavian vein, for cardiac ablation, and then advancing the catheters toward a target treatment site within or on the surface of the heart.

[0004] The primary ablation approach to cardiac arrhythmia treatment involves either directly eliminating the arrhythmogenic substrate by disrupting it or preventing nonphysiological action potential propagation by linear or circular isolation. Both of these approaches require the creation of a lesion that essentially blocks myocardial action potential propagation. By applying energy, small portions of myocardium are locally destroyed and converted into nonmyocardial connective tissue by natural physiological processes within a few weeks.

[0005] Common ablation methods known from the prior art are based on the thermal destruction of tissue by either high or low temperatures. Such methods include, for example, heating the target tissue by a radio frequency field (RF) or a laser, or freezing the tissue by cryoablation. These methods cause necrosis of the target tissue, which can add risks to the procedure.

[0006] Recently, methods and devices using electric fields for ablation have been utilized. The purpose of these methods is to induce irreversible electroporation of cell membranes to cause tissue destruction instead of destruction by high or low temperatures, thereby reducing the drawbacks and risks of ablation procedures that are primarily based on thermal damage. However, there are still drawbacks that need to be resolved.

[0007] A common design for such devices is a catheter with a distal tip containing one or more electrodes. The catheter may have, for example, a single active electrode at the tip. An unrelated electrode may be placed on the patient's skin, for example. Ablation of the target treatment site using such a device must be performed point-by-point, which increases the duration and complexity of the procedure.

[0008] Another example of a conventional device is a catheter with a row of electrodes at the distal tip of a single catheter body. The distal tip of such a catheter is delivered near a target treatment site and deployed (bent) into a specific shape near the target treatment site. While such a shape allows for the use of two or more electrodes for treatment and requires less movement at the distal tip, deploying the catheter into the correct shape and properly positioning and maneuvering such a catheter can be very difficult. Similarly, unrelated electrodes can be placed on the patient's skin, or ablation can be performed in a bipolar fashion between specific electrodes located at the distal end of the catheter.

[0009] Devices with catheter terminal baskets containing a single strut carrying an electrode are also known in the prior art. Such devices can ensure easier deployment and positioning relative to the target site. Because more electrodes are typically located on the catheter terminal, ablation can again be either monopolar, with an unrelated electrode placed on the patient's skin, for example, or bipolar between specific electrodes on the catheter terminal. One drawback of this solution is the limited number of struts, which means that a limited number of electrodes create a specific circular pattern in space. This drawback stems from the need for mechanical stability of specific struts to ensure the basket maintains a stable shape. This means that the struts must be sufficiently rigid and maintain specific dimensions. The number of struts used is then limited by the size of the catheter. Another drawback of this solution is that such a structure cannot fully guarantee the mutual distance of the struts in the deployed configuration, which means that the distance between the electrodes cannot be guaranteed. This means that the device may need to be repositioned multiple times to ensure proper ablation, which extends the duration of the procedure.

[0010] There is a need to increase the quality and safety of ablation while reducing patient risk and treatment duration. Thus, there is a need for improved ablation devices and methods that are gentler and safer for the patient, with reduced complexity and improved quality and reliability of the methods and devices themselves. Summary of the Invention

[0011] Disclosed herein are ablation system devices and methods, in particular ablation methods and devices for pulsed field ablation with electric fields according to the description, which can address and solve the above-mentioned problems, are gentler and safer for the patient, require less time and technical complexity, and improve the quality, effectiveness and reliability of the systems, methods and devices themselves. [Brief explanation of the drawings]

[0012] Exemplary aspects of the present disclosure are illustrated by way of example in the accompanying drawings, in which like reference numerals indicate the same or similar elements.

[0013] [Figure 1] FIG. 1 is a block diagram of an exemplary ablation system.

[0014] [Figure 2] 1 is a schematic of an exemplary pulsed field ablation device with a catheter.

[0015] [Figure 3A] 1 illustrates an exemplary catheter having a shaft assembly.

[0016] [Figure 3B] 1 is an exemplary cross-sectional view of a shaft assembly.

[0017] [Figure 4] 1 is an exemplary representation of a distal tip of a catheter having a basket assembly in an expanded configuration.

[0018] [Figure 5] 1 illustrates an exemplary distal tip of a catheter having a basket assembly in a collapsed configuration.

[0019] [Figure 6A] 1 illustrates an exemplary expandable basket.

[0020] [Figure 6B] FIG. 10 is a detailed view of an exemplary expandable basket with filaments.

[0021] [Figure 6C] FIG. 10 is a detailed view of an exemplary expandable basket with filaments and conductive wires.

[0022] [Figure 7A] FIG. 1 is a front view of an exemplary distal tip of a catheter.

[0023] [Figure 7B] FIG. 1 is a side view of an exemplary distal tip of a catheter.

[0024] [Figure 8] 1 illustrates an exemplary braided mesh with elongated electrodes.

[0025] [Figure 9] 1 shows an exemplary braided mesh having filaments and conductive wires inside the lumens of the filaments.

[0026] [Figure 10] 10A-10C are exemplary schematic diagrams of the position of the basket assembly adjacent to the treatment site.

[0027] [Figure 11] 1 is a schematic diagram of an exemplary mode of operation of an electrode.

[0028] [Figure 12] 10 is a schematic diagram of another exemplary mode of operation of the electrodes. FIG.

[0029] [Figure 13A] 1 is an example of a spatial pattern of electrodes at the distal tip of a catheter.

[0030] [Figure 13B] 1 is another example of a spatial pattern of electrodes at the distal tip of a catheter.

[0031] [Figure 14] 10 is a diagram of a possible layout of electrodes already switched to a hybrid mode of operation. FIG.

[0032] [Figure 15A] 1 shows an exemplary pattern of electrodes.

[0033] [Figure 15B] 10 shows another exemplary pattern of electrodes.

[0034] [Figure 15C] 10 shows another exemplary pattern of electrodes.

[0035] [Figure 16] 1 illustrates a portion of an exemplary pulsed field ablation protocol.

[0036] [Figure 17a] Examples of inter-pulse pauses with voltages different from 0V are shown.

[0037] [Figure 17b] 1 shows examples of different biphasic pulses.

[0038] [Figure 18] FIG. 1 illustrates an example of a terminal assembly.

[0039] [Figure 19] 1 illustrates another view of an exemplary terminal assembly.

[0040] [Figure 20] 1 shows an example of filaments joined to each other at their intersections.

[0041] [Figure 21] FIG. 10 is a view of the distal portion of a basket assembly having a merging structure and a living hinge.

[0042] [Figure 22] 1 shows an example of a filament produced by a molding process.

[0043] [Figure 23] FIG. 1 is an example of a partially braided mesh containing filaments produced by a molding process.

[0044] [Figure 24a] 1 is an example of a flat braided mesh made by a molding process.

[0045] [Figure 24b] 1 shows a flat formed braided mesh bent into the shape of a tube.

[0046] [Figure 24c] 1 shows a plurality of planar molded meshes bent into the shape of a tube.

[0047] [Figure 25a] 1 is a diagram of an example of a formed mesh formed as a three-dimensional structure.

[0048] [Figure 25b] 1A-1C are diagrams of examples of molded expandable baskets.

[0049] [Figure 26] 1 shows two filaments formed by molding to create a merged structure.

[0050] [Figure 27] 1 illustrates an exemplary arrangement of mold components configured for injection molding of filaments.

[0051] [Figure 28] 1 is a cross section of an expandable basket secured to an inner elongate shaft.

[0052] [Figure 29] 10A-10C are diagrams of examples of an inner elongate shaft end and an expandable basket before and after mechanical attachment to one another.

[0053] [Figure 30a] FIG. 10 is a cross-sectional view of an expandable basket secured to an inner elongate shaft.

[0054] [Figure 30b] 10A-10C show detailed views of exemplary protrusions of the inner elongate shaft.

[0055] [Figure 31a] 1 shows a cross section of a filament at various manufacturing steps.

[0056] [Figure 31b] 10A-10C show cross sections of a filament at different manufacturing steps.

[0057] [Figure 31c] 10 shows another cross section of the filament at another manufacturing step.

[0058] [Figure 32] FIG. 2 is a block diagram of a pulse generator.

[0059] [Figure 33] FIG. 1 is a schematic diagram of an improved half-bridge.

[0060] [Figure 34] 1 shows the layout of electrodes imprinted on a two-dimensional plane. DETAILED DESCRIPTION OF THE INVENTION

[0061] Detailed Description FIG. 1 illustrates an ablation system (100) for pulsed field ablation of target tissue. The ablation system (100) described herein includes a pulsed field ablation device (101). The ablation system (100) may include or be connected to other parts or devices suitable for performing or supporting the pulsed field ablation methods described herein. The other parts or devices may be, for example, a control unit (111), a graphical user interface (GUI) unit (113), an electrical control circuit (115), an electrocardiogram (ECG) trigger circuit (117), an ECG recording device (129), ECG electrodes (125), a pacing device (131), a catheter signal interconnect circuit (119), and / or an electrophysiology (EP) display device (133), which may include an EP recording system. The EP display device may display and / or record data from one or more other devices connected to the ablation system (100). Additionally, the ablation system (100) can include a mapping device (135), such as a three-dimensional (3D) mapping device or a real-time position measurement (RPM) device, and / or an unrelated electrode (127). The mapping device (135) records, for example, EGMs (intracardiac electrograms) of locations in space measured by the catheter, creating a map of the heart's surface. This can also indicate the position and orientation of the catheter. Other possible methods for measuring the actual position of the catheter can be via sensors in the catheter (e.g., magnetic-based localization), or using, for example, impedance measurements at the catheter's electrodes, or measurements based on radio frequency or a combination thereof. Advantageously, in some instances, the catheter used for localization is the same catheter used for ablation.

[0062] The pulsed field ablation device (101) includes a pulse generator (103) for generating short, high-voltage electrical pulses, and a catheter (105) suitable for insertion into a body cavity of a patient, the catheter having a distal tip (107) suitable for performing pulsed field ablation of target tissue with a pulsed electric field using a set of electrodes (109). The catheter (105) is in electrical communication with the pulse generator (103).

[0063] The generator (103) may be configured to generate high voltage electrical pulses having a frequency of, for example, 0.1 Hz to 10 Hz, with monophasic pulse amplitudes varying from 100 V up to 5 kV and biphasic pulse amplitudes varying from 200 V to 10 kV peak-to-peak. The pulse durations may range from the nanosecond range to the millisecond range. An exemplary schematic of the generator (103) can be seen in FIG. 32.

[0064] The generator (103) may include a power supply unit (3200) capable of generating an operating voltage at its output, for example, between 100V and 5000V, or between 250V and 2000V, or between 500V and 1000V. The power supply unit (3200) may also transfer AC current, for example, from a current source (3202), to DC current at the output of the power supply unit (3200), for example, from a plug. The power supply unit (3200) may have an output power of between 100W and 5000W, or between 200W and 3000W, or between 500W and 1000W. The power supply unit (3200) may include a regulator (3201) for regulating the generation of the operating voltage. The operating voltage may be regulated, for example, by switching it on and off, according to feedback from the power supply unit (3200) output. The power supply unit (3200) may comprise, for example, a switched mode power supply (3208) configured to vary the voltage coming from the current source (3202), for example, to vary it from about 230 V to about 400 V, a safety transformer (3209) (e.g., an AC-DC transformer), a power factor correction (PFC) circuit block (3210), and / or at least one DC / DC converter (3211). The power supply unit (3200) may also be coupled to the electrical control circuit (115) and may be regulated, for example, to be switched on and off according to a signal from the electrical control circuit (115).

[0065] The output of the power supply unit (3200) may be coupled to a capacitor unit (3203) including at least one capacitor (3212). The capacitor unit (3203) generates energy for the high-voltage electrical pulse. The capacitance of the capacitor unit (3203) may be, for example, 50 μF to 1500 μF, or 80 μF to 1000 μF, or 160 μF to 750 μF. The capacitor unit (3203) may include an emergency system (3207) capable of triggering emergency dissipation of charge from the capacitor unit (3203) in the event of a fault or if any measured parameter is outside the safety boundary of the pulsed field ablation device (101). The emergency system (3207) may include a safety discharge resistor configured to safely discharge the capacitor (3212), e.g., a thyristor protection and / or a contactor configured to short-circuit the capacitor (3212) if necessary. The operating speed of the emergency system (3207) may be, for example, 50 ms to 100 ms.

[0066] The generator may further include a switching unit (3204) that may include at least one switch (3205), such as a semiconductor switch. The input of the switching unit (3204) may be coupled to the capacitor unit (3203), and the output of the switching unit (3204), and therefore the switch (3205), may be coupled to at least one electrode (109) and configured to switch the electrode (109) between a first polarity mode, a second polarity mode, and a high impedance mode. The number of switches (3205) may depend on the number of independently switchable electrodes or groups of independently switchable electrodes (109). One switch (3205) may be coupled to one electrode (109) or multiple electrodes.

[0067] The switch 3205 may be a semiconductor switch, such as an improved half bridge 3300. A schematic diagram of the improved half bridge 3300 can be seen in FIG. 33. The improved half bridge 3300 is an improvement over a conventional half bridge. It solves the problems of the conventional half bridge's parasitic characteristics, such as closed-state leakage current and output capacitance. The improved half bridge 3300 may include a top surface and a bottom surface. An upper transistor 3301 is coupled to a common collector. An upper resistor 3302 is coupled to the emitter of the upper transistor 3301 and to ground. Due to the placement of the upper resistor 3302, the voltage across the upper resistor 3302 is near zero when the upper transistor 3301 is closed. The improved half bridge 3300 may further include an upper diode 3303. The upper diode (3303) is coupled through its anode to the emitter of the upper transistor (3301) and through its cathode to the output (OUT) of the half bridge (3300). When the upper transistor (3301) is closed (high impedance state), the upper diode (3303) can ensure that current from the output of the half bridge (3300) does not pass through the upper resistor (3302). The bottom transistor (3304) has a common emitter, and there is a bottom resistor (3305) coupled to the collector of the bottom transistor (3304). The bottom resistor (3305) is coupled to the positive power supply (+). Due to the bottom resistor (3305), the voltage across the bottom resistor (3305) is close to zero when the bottom transistor (3304) is closed. The bottom diode (3306) is connected in reverse, i.e., the anode of the bottom diode (3306) is coupled to the output (OUT) of the modified half bridge (3300) and the cathode is coupled to the collector of the bottom transistor (3304), preventing the output (OUT) of the modified half bridge (3300) from having a permanent output voltage.

[0068] In instances where the switching unit (3204) is directly coupled to the capacitor unit (3203), patient or operator safety may depend on the reliability of at least one switch (3205). In the event of a switch (3205) failure, the patient or operator may face uncontrolled dissipation of the high capacitance of the capacitor unit (3203) for a period of 50 ms to 100 ms.

[0069] For example, to address such risks to the patient or operator, at least one DC / DC converter unit (3206) can be coupled between the capacitor unit (3203) and the switching unit (3204). The DC / DC converter unit (3206) can have an input voltage of 100V to 5000V, 250V to 2000V, or 500V to 1000V, and an output voltage of 150V to 5000V, 500V to 3000V, or 1000V to 2000V. The DC / DC converter unit (3206) can include, for example, an output capacitor (3213) at its output.

[0070] The DC / DC converter unit (3206) can include an output capacitor emergency system (3214) that can cause emergency dissipation of capacitance from the output capacitor (3213) and interrupt voltage delivery from the generator (103) to the electrodes (109) in the event of any fault or any measured parameter outside the safety boundary of the pulsed field ablation device (101). The output capacitor emergency system (3214) can include a safety discharge resistor configured to safely discharge the output capacitor (3213), e.g., a thyristor protection and / or a contactor configured to short-circuit the output capacitor (3213) if necessary. The emergency dissipation of capacitance from the output capacitor (3213) and interruption of voltage supply from the generator (103) to the electrodes (109) can take less than 50 ms, or less than 25 ms, or less than 15 ms, or less than 5 ms, or less than 1 ms, or less than 100 μs, or less than 10 μs.

[0071] The capacitance of the output capacitor (3213) may be, for example, 1 μF to 200 μF, or 1.5 μF to 100 μF, or 2 μF to 50 μF, or 5 μF to 30 μF. The DC / DC converter unit (3206) may be, for example, a DC / DC converter without feedback. The DC / DC converter unit (3206) may be configured to convert the high capacitance of the capacitor unit (3203) into a lower capacitance in the output capacitor (3213). The DC / DC converter unit (3206) may further be configured to rapidly discharge the capacitance of the output capacitor (3213). The DC / DC converter unit (3206) may further be configured, for example, to limit leakage current from the power supply unit (3200) to the patient to, for example, less than a limit of 10 μA. The leakage current may be generated, for example, by parasitic capacitance of the windings of the power supply unit (3200). The DC / DC converter unit (3206) may include two windings and may be, for example, a series resonant converter. The DC / DC converter unit (3206) may have a conversion ratio of, for example, 1:1 to 1:6, or 4:5 to 1:4, or 2:3 to 1:3.

[0072] The power supply unit (3200), capacitor unit (3203), DC / DC converter unit (3206), switching unit (3204), and / or current source (3202) may be coupled to one or more electrical control circuits (115). The electrical control circuits (115), for example, may receive data from and / or send control signals to the power supply unit (3200), capacitor unit (3203), DC / DC converter unit (3206), switching unit (3204), and / or current source (3202). The data may include, for example, measured parameters at various locations of the pulsed field ablation device (101), generator (103), power supply unit (3200), capacitor unit (3203), DC / DC converter unit (3206), switching unit (3204), and / or current source (3202). The measured parameters may be, for example, temperature, impedance, current, or voltage. The voltage can be measured, for example, at the output of the power supply unit (3200), the capacitor unit (3203), the DC / DC converter unit (3206), the current source (3202), and / or the switching unit (3204), for example, at the output of at least one switch (3205).

[0073] The electrical control circuitry (115) can evaluate the received data and, based on the received data, send control signals to the power supply unit (3200), the capacitor unit (3203), the DC / DC converter unit (3206), the current source (3202), the switching unit (3204), and / or other parts of the ablation device (101). If at least one of the measured parameters falls outside predetermined boundaries, the electrical control circuitry (115) can send control signals to the power supply unit (3200), the capacitor unit (3203), the DC / DC converter unit (3206), the switching unit (3204), for example, to initiate a safe disconnection of a particular unit or all or a subset of the units. Safe disconnection may mean, for example, turning off the power supply unit (3200) and activating the emergency system (3207) of the capacitor unit (3203) (discharging the capacitor (3212) to a safety discharge resistor and / or shorting the capacitor (3212) via a thyristor protection and / or contactor). In the DC / DC converter unit (3206), safe disconnection may mean activating the output capacitor emergency system (3214) (discharging the output capacitor (3213) to a safety discharge resistor and / or shorting the output capacitor (3213) via a thyristor protection and / or contactor). In the switching unit (3204), safe disconnection may mean disconnecting at least one switch (3205).

[0074] The pulsed field ablation device (101) may include or be connected to other parts or devices suitable for performing or supporting the pulsed field ablation methods described herein. The other parts or devices may be, for example, a remote control unit (111), a graphical user interface (GUI) unit (113), an electrocardiogram (ECG) device including an electrical control circuit (115), an ECG trigger circuit (117), an ECG recording device (129), ECG electrodes (125), a pacing device (131), a catheter signal interconnect circuit (119), and / or an electrophysiology (EP) display device (133), which may include an EP recording system. The EP display device may display and / or record data from other devices connected to the ablation system (100). Additionally, the ablation system (100) may include a mapping device (135), such as a three-dimensional (3D) mapping device or a real-time position measurement (RPM) device, and / or an extraneous electrode (127). For example, the pulsed field ablation device (101) can be configured for use within or on a patient's heart, e.g., for the treatment of cardiac tissue, e.g., for pulsed field ablation of cardiac tissue, e.g., for pulsed field ablation of myocardial tissue, e.g., for pulmonary vein isolation. The devices and methods disclosed herein can be used elsewhere, e.g., in any tubular tissue, organ, or vessel within the body, or at the site of, e.g., a tumor.

[0075] The catheter (105) shown in Figure 2 includes a shaft assembly (201) and a catheter distal tip (107) disposed adjacent to the distal portion of the catheter (105). The shaft assembly (201) defines a central longitudinal axis (203) of the catheter (105). The catheter (105) may further include a handle assembly (123) and a connecting assembly (121). The catheter (105) may be steerable or non-steerable and may be introduced into position, for example, via an introducer sheath (not shown), with or without the aid of a guidewire (not shown).

[0076] The connection assembly (121) of the catheter (105) can serve to interconnect the catheter (105) with other portions of the ablation system (100). The connection assembly (121) can include a single connection portion or more spatially separated connection portions. The connection assembly (121) can be located in a proximal portion of the catheter (105) and / or can be part of, for example, the handle assembly (123). The connection assembly (121) portion can include, for example, one or more electrical connections, mechanical connections, fluid connections, and / or inputs for guidewires.

[0077] The connection assembly can include at least one connector, such as an electrical connector, a fluid connector, a data connector, an optical connector, etc. The connector can serve to connect and disconnect the catheter (105) to other portions of the ablation system (100).

[0078] The handle assembly (123) may be attached to the catheter shaft assembly (201) and may function, for example, to steer and manipulate the catheter (105) and / or precisely control the movement and deflection of the catheter (105). To enable steering functions, there may be a knob (not shown) attached adjacent to the distal section of the catheter (105) that is fed through a separate lumen and connected to steering wires (not shown), which may be connected to a knob or steering mechanism (not shown) inside the handle assembly (123). The handle assembly (123) may further include a grip (not shown) and / or a deployment mechanism (not shown) that deploys / retracts the distal tip basket assembly (401, see FIG. 4 ) and / or the expandable basket (409) by pushing / pulling the connection assembly (121) or one or more connecting portions of the connection assembly (121) and other portions, such as the inner elongate shaft (301) and / or outer elongate shaft (303) relative to one another. The deployment mechanism can include, for example, an actuator for longitudinally actuating the inner elongate shaft (301) relative to the outer elongate shaft (303).

[0079] FIG. 3A shows a catheter (105) having a shaft assembly (201). The shaft assembly may include an outer elongate shaft (303) and / or an inner elongate shaft (301). A cross section of the exemplary shaft assembly (201) at section AA shown in FIG. 3B may include two concentric tubes, the outer tube being the outer elongate shaft (303) and the inner tube being the inner elongate shaft (301). The shafts can translate longitudinally relative to one another along the central longitudinal axis (203). This translation may, for example, allow the expandable basket (409) to be deployed / retracted from a collapsed configuration to a fully expanded configuration and back again.

[0080] The outer elongate shaft can include a proximal portion, a distal portion, and a body extending between the proximal and distal ends. The outer elongate shaft can be coupled to a handle assembly adjacent its proximal portion and to a catheter distal tip adjacent its distal portion.

[0081] The body of the outer elongate shaft (303) can include one or more lumens (309, 311), e.g., extending along its entire length between the proximal and distal ends. The lumens can accommodate, for example, lead wires or fluids, such as irrigation fluid. One or more of the lumens can be configured to receive one or more of the inner elongate shafts. The body of the outer elongate shaft can be further defined, for example, by a proximal section (305) and a central section (307). The central section of the body can be designed with a more flexible jacket compared to the proximal section, allowing for bending of the outer elongate shaft and increasing its flexibility. The proximal section includes a more rigid material jacket, e.g., to increase the torque and stiffness of the body of the outer elongate shaft. Suitable materials for the construction of the jacket include, but are not limited to, nylon, TPU, HDPE, or PEBA.

[0082] The body of the outer elongate shaft can include conductive wires. The conductive wires can pass through a central lumen (309) of the outer elongate shaft, or the outer elongate shaft can include several other lumens (311), such that one or more of the wires can pass through one or more of the other lumens (311). For example, the number of other lumens can correspond to the number of filaments in the braided mesh of the catheter distal tip; for example, if 20 filaments are used to construct the catheter distal tip, 20 other lumens can be used.

[0083] The conductive wires may extend from the basket assembly to a connection assembly, for example, adjacent the handle assembly.

[0084] In some embodiments, the inner elongate shaft can be configured to slide relative to the outer elongate shaft along the central longitudinal axis. Accordingly, one or more of the lumens can include, for example, a low-friction liner, such as a polytetrafluoroethylene (PTFE) liner.

[0085] Stiffness and torque are important characteristics for the outer elongate shaft to possess, and therefore the outer elongate shaft can comprise a braid of metal or rigid polymer wire wrapped around the inner layer of the body, for example, laterally over / around a PTFE liner, and in some embodiments embedded within the outer jacket of the body, or can comprise a rigid polymer, including but not limited to, polyimide, polyamide, polyetheretherketone (PEEK), or any other suitable material.

[0086] The outer layer of the outer elongate shaft may comprise a laminated polymer to provide a seamless, smooth, and soft surface. As previously mentioned, the outermost layers of the central and proximal sections may be formed from different polymers; for example, a nylon material may be used for the proximal section, while a PEBA, which is more flexible than nylon, may be used for the outermost layer of the central section. However, both sections may have the same innermost layer. The outer elongate shaft may have a substantially constant outer diameter along its length.

[0087] The outer diameter (OD) dimension of the outer elongate shaft can conform, for example, to the French catheter scale, which is commonly used to standardize catheter sizes. Diameters on this scale are defined in French (FR), where 1 mm = 3 FR. The scale typically ranges from 3 FR catheters to 34 FR catheters. For example, the diameter of the outer elongate shaft can be between 5 FR and 20 FR, or between 7 FR and 16 FR, or between 9 FR and 15 FR. The diameter of the central lumen of the outer elongate shaft can be approximately 0.1 mm to 5 mm, or between 1 mm and 4 mm, or between 2 mm and 3.5 mm, or between 2.5 mm and 3 mm.

[0088] The inner elongate shaft may include a proximal end, a distal end, and a body extending between the proximal and distal ends. The body of the inner elongate shaft may include one or more lumens (313), for example, extending along the entire length of the inner elongate shaft between the proximal and distal ends, or may be lumenless. The one or more lumens (313) of the inner elongate shaft may be designed, for example, to accommodate a standard guidewire (not shown) and / or to conduct fluid, such as irrigation fluid. The diameter of the one or more lumens (313) may be 0.1 mm to 3 mm, or 0.5 mm to 1.5 mm, or 0.9 mm to 1 mm, or 0.94 mm to 0.99 mm. One or more of the inner elongate shafts may be adapted for placement in one or more lumens (309, 311) of the outer elongate shaft. The dimensions of the inner elongate shaft can be selected to match the diameter of the designated lumen of the outer elongate shaft, but the two structures must still allow for smooth relative movement between them. That is, the outer dimensions of the inner elongate shaft (301) can be 0.1 mm to 4.9 mm, or 0.5 mm to 3.5 mm, or 1 mm to 3 mm, or 1.28 mm to 2.8 mm.

[0089] The inner elongate shaft may be adapted to accommodate a guidewire within its lumen, so that a low friction liner of the inner lumen, such as a PTFE liner, may be used.

[0090] As mentioned above, the inner elongate shaft can translate relative to the outer elongate shaft to deploy the basket assembly / expandable basket, and thus, for example, a braided socket can be woven along the length of the PTFE liner to form the body of the inner elongate shaft. Another embodiment can include a cut hypotube in place of the braid in the body of the inner elongate shaft to improve its flexibility and torque.

[0091] A polymer jacket can be melt / laminated laterally over the layer with the braid or hypotube to increase the flexibility of the tube and provide a seamless surface. A variety of polymers can be used for the jacket; exemplary materials can be NYLON, polyether block amide (PEBA), polyether ether ketone (PEEK), or polyimide.

[0092] The distal tip portion (107) of the example catheter shown in Figure 4 further includes a basket assembly (401). The basket assembly (401) can include a basket assembly proximal portion (403), a basket assembly distal portion (405), and a basket assembly body (407) extending between the proximal and distal portions. The basket assembly body can include a central body portion (419) that occupies approximately one-third of the basket assembly body and extends about a plane (425) that intersects the basket assembly at a portion having a largest diameter in the proximal and distal directions (in one of its expanded configurations). The basket assembly body can further include a distal body portion (421) extending distally from the central body portion (419) and a proximal body portion (423) extending proximally from the central body portion (419), each of which occupies approximately one-third of the basket assembly body (407).

[0093] The basket assembly (401) includes an expandable basket (409). The basket assembly proximal portion (403) can include attachment of the proximal portion of the expandable basket (409) adjacent to the distal end of the outer elongate shaft (303). The distal portion of the basket assembly (401) can include attachment of the distal portion of the expandable basket (409) adjacent to the distal end of one or more of the inner elongate shafts (301) that form the contact assembly (411).

[0094] An example of the attachment of the distal portion of the expandable basket (409) adjacent to the distal end of one or more of the inner elongate shafts (301) can be seen in FIG. 28. In this particular example, the distal end of the expandable basket (409) can be created with the aid of a ring (2801) to which the filament (415) is secured or bent at a location (2804) that secures the filament (415) to the ring (2801). The distal portion of the expandable basket (409) is attached to the inner elongate shaft (301) by a mechanical locking mechanism. To lock the basket to the shaft, for example, two protrusions (2802, 2803) are formed on the inner elongate shaft (301) to hold either side (proximal and distal) of the basket distal end, including the ring (2801), which locks the expandable basket (409) to the inner elongate shaft (301). The assembly is created by pushing the inner elongate shaft (301) with the prepared first protrusion (2802) distally through an opening in the distal portion of the expandable basket, e.g., through a hole in the ring (2801), until the first protrusion (2802) on the shaft reaches the distal portion of the expandable basket from the proximal side, as shown in Figure 29. The inner elongate shaft end (2901) (that protruding distally from the basket) is then tipped / heated in a bullet-shaped mold to form a second protrusion (2803) with an atraumatic bullet-shaped end that prevents the inner elongate shaft (301) from moving proximally relative to the expandable basket (409). This connection is made in a way that locks the inner elongate shaft (301) to the expandable basket (409) under operating conditions, but also in a way that the connection breaks loose under certain axial loads if the basket is not undeployable and the catheter needs to be withdrawn from the patient. The axial load (force) required to brake the connection may be between 10N and 100N, or between 15N and 75N, or between 20N and 50N.

[0095] The protrusions (2802, 2803) may be formed on the inner elongate shaft by other techniques as well. One particular example is shown in FIGS. 30a and 30b. The second protrusion (2803), in this example, may be formed by a distal addition member (3001) coupled to the inner elongate shaft (301), e.g., the inner elongate shaft end (2901). The distal addition member (3001) may be in the form of, for example, a toroid, a cylinder, a cone, a frustoconical, or a hollow tubular body, e.g., with an atraumatic shape (e.g., bullet-shaped, flange-shaped) formed at its distal end to ensure that the terminal assembly does not mechanically injure the patient, and may be made of, for example, plastic or metal. The distal addition member (3001) may include a tubular structure (3002) protruding proximally from the second protrusion (2803) parallel to the inner elongate shaft. The distal addition member (3001) and / or the tubular structure (3002) can include a cavity (3006) adapted to receive, for example, at least a portion of the inner elongate shaft (301), e.g., the inner elongate shaft end (2901), and a guidewire. The cavity (3006) can have two inner diameters: a first diameter (3007) formed proximal to the distal addition member (3001) that is large enough to fit over at least a portion of the inner elongate shaft (301), e.g., the inner elongate shaft end (2901), and a second diameter (3008) formed distal to the first diameter (3007) that is smaller than the first diameter (3007), e.g., smaller than the outer diameter of the inner elongate shaft (301) configured to pass a guidewire therethrough. Such a configuration of the cavity (3006) allows the distal additional member (3001) to act as a distal stop for the inner elongate shaft (301) in the direction of the longitudinal central axis (203), while also preventing possible sharp edges of the inner elongate shaft end (2901) from being exposed distal to the distal additional member (3001) and possibly causing tissue damage upon contact.The distal additional member (3001) may be coupled to the inner elongate shaft (301), and the coupling may include, for example, crimping, welding, screws, threads, molten plastic, or adhesive, such as a hot melt adhesive or glue.

[0096] In the specific example shown in Figures 30a and 30b, the distal add-on member (3001) can be bonded to the inner elongate shaft (301), for example, by molten plastic or adhesive. The distal add-on member (3001) can include a cavity having a diameter larger than the outer diameter of the inner elongate shaft (301), for example, 0.1% to 50%, or 0.5% to 40%, or 1% to 25% larger. The inner elongate shaft can be inserted into the cavity, and the resulting space (3003) between the inner elongate shaft (301) and the cavity wall can be filled with an adhesive, for example, a hot melt adhesive or glue. The distal add-on member (3001) can include an adhesive opening (3004) for this purpose, which can provide access for the adhesive into the resulting space (3003). After filling the resulting space (3003) with adhesive, the adhesive opening (3004) can be closed and sealed, for example, by a plug, molten plastic, or by adhesive, for example a hot melt adhesive or glue, possibly the same as that used to bond the distal additional member (3001) to the inner elongate shaft (301).

[0097] The first protrusion (2802), as illustrated in Figures 30a and 30b, may be formed, for example, by a tubular proximal addition member (3005) coupled to the inner elongate shaft (301). The proximal addition member (3005) may be directly coupled to the inner elongate shaft (301), or may be coupled to the inner elongate shaft (301) via, for example, a distal addition member (3001), such as to a tubular structure (3002). In another example, shown in Figures 30a and 30b, the proximal addition member (3005) may be coupled to the inner elongate shaft (301) both directly and indirectly via the distal addition member (3001). The coupling of the proximal addition member (3005) to the inner elongate shaft (301) and / or to the distal addition member (3001) can include, for example, crimping, welding, screws, threads, molten plastic, adhesive, such as a hot melt adhesive or glue, or another fastening member (not shown), for example, positioned proximally on the inner elongate shaft (301). The first protrusion (2802) can have a shape and can include, for example, a plastic tube.

[0098] The ring (2801) to which the filament (415) is secured can be coupled directly to the inner elongate shaft (301) or via, for example, a distal additional member (3001) or a proximal additional member (3005). An example of a ring (2801) coupled to the inner elongate shaft (301) via a distal additional member (3001) is shown in Figures 30a and 30b. In this particular example, the distal additional member (3001) includes a tubular structure (3002) protruding proximally from a second protrusion (2803) parallel to the inner elongate shaft, and the ring (2801) can surround the tubular structure (3002).

[0099] The terminal assembly (411) can be advantageously designed without, or at least with a reduced structure, such as a cap or similar formation, protruding distally from the basket assembly distal portion (405), which is particularly advantageous in situations where at least part of the ablation procedure needs to be performed in a relatively flat treatment site.

[0100] An exemplary solution for the terminal assembly may be an overmolded structure. The filaments may be secured to one another and / or to the distal end of the inner elongate shaft by an overmolding process to form an overmolded terminal assembly. Another securing procedure (and / or terminal assembly fabrication procedure) similar to overmolding may be, for example, tilting, in which the filaments are at least partially melted and forced into a pre-shaped mold, thus connecting them to one another and / or to the inner elongate shaft. Lamination is another exemplary process for securing the filaments to their distal ends to form the terminal assembly. The terminal assembly may also be fabricated by swaging or crimping the distal ends of the filaments. The filaments may be joined together in the terminal assembly area and, for example, swaged or crimped together by some type of metal ring.

[0101] In another example, the terminal assembly may be fabricated as a hinged mechanical structure, as shown in FIG. 18 . For example, one or more filaments may be at their distal ends in a region of the terminal assembly secured to an articulation element (1801), which may include, for example, a lateral narrow portion (1803) and a distal portion (1805) that is wider than the lateral narrow portion (1803). The lateral narrow portion (1803) may be in the form of a pin having, for example, a square, rectangular, circular, elliptical, or other suitable cross-section. The distal portion (1805) may have, for example, an elliptical or circular shape, or in another example, a ball or sphere shape. Other possible shapes of the distal portion (1805) may be cylindrical, conical, cubical, or block-shaped. This can have one of the same dimensions as the lateral narrow portion (1803), for example, if the entire articulating element (1801) is made from a single piece of sheet material (metal sheet, polymer sheet), or if not (for example, if the articulating element is cast or forged). The articulating element (1801) can be made, for example, from a metal (e.g., nitinol) or other material, such as a polymer or thermoplastic. The filament can be secured to the articulating element by, for example, welding, gluing, or crimping. The connection area (1807) can be at least partially laminated, for example, to prevent possible tissue damage and seal the assembly. The articulating element is then secured within a central projectile structure (1809). This can be, for example, a hollow structure with a cutting window (1811) suitable for receiving the proximal portion (1803) of the articulating element (1801). In this case, the distal portion (1805) of the articulating element is positioned within the inner cavity (1813) of the hollow structure. The distal portion (1805) of the articulation element may, in some instances, have a dimension (cross-section or width) that is greater than the dimension of the window (1811), thereby preventing slippage of the distal portion (1805) of the articulation element (1801) through the window (1811), thus retaining the articulation element, and with it the distal portion of the filament attached to the connection region (1807) and central bullet structure (1809).The central bullet structure (1809) can include several sections connected to each other (e.g., by welding, gluing, or other mechanical means such as snaps, threading, screws, bolts, etc.). It can also have different external shapes, e.g., cylindrical, spherical, or elliptical. The shape of the cavity (1813) can correspond to the external shape or can be different. The central bullet structure can include a fixing portion (1815) for fixing the distal end of the inner elongate shaft to the central bullet structure. The fixing portion (1815) can have, for example, the shape of a hollow tube connected to the central bullet structure. The fixing portion is suitable for receiving and / or connecting the distal portion of the inner elongate shaft and can allow the flow and / or redirection of fluids, e.g., irrigation fluids, emerging from the lumen of the inner elongate shaft. The fixing portion can interface with the cavity (1813) or can be mechanically and / or fluidically connected thereto. This may be adapted to direct at least a portion of the irrigation fluid into the cavity of the central projectile structure, for example by means of an opening (1901) as shown in FIG.

[0102] Such hinge mechanical structures as described above can allow for easier radial movement (relative to the central longitudinal axis of the catheter) of the filament in the region of the terminal assembly, which can be advantageous during operation with the expandable basket, particularly in the transition (deployment / retraction) between a collapsed configuration and one or more expanded configurations.

[0103] When metal components are used in the design of the terminal assembly, they can be used as electrodes, for example, for ablation or sensing or mapping or a combination thereof.

[0104] The expandable basket may be attached to the inner and / or outer elongate shafts, for example, by gluing, welding, laminating, or by mechanical means.

[0105] The expandable basket (409) is configured for transition (deployment / retraction) between a collapsed configuration, for example, as shown in FIG. 5, and one or more expanded configurations. The transition (deployment / retraction) may be caused by the shape of the pretensioned braided mesh (413) and / or filaments (415), and / or by linear displacement of the inner elongate shaft (301) relative to the outer elongate shaft (303) along the central longitudinal axis (203) of the catheter (105), or a combination thereof. Another possibility for deployment / retraction of the expandable basket (409) may be by the tension of an additional support structure, such as an inner coil or balloon (not shown).

[0106] The expandable basket can include filaments braided into a braided mesh or a shaped mesh. In the collapsed configuration, the cross-section of the expandable basket can be equal to or close in size to the cross-section of the outer elongate shaft, although in some embodiments, the cross-section of the expandable basket can be smaller than the cross-section of the outer elongate shaft, depending on the dimensions of the outer elongate shaft. In the expanded configuration, the cross-section of the expandable basket can be significantly larger than the cross-section of the outer elongate shaft. The fully expanded expandable basket can have a maximum cross-sectional diameter of, for example, 20 mm to 40 mm, or 22 mm to 38 mm, or 25 mm to 35 mm. Such dimensions of the fully expanded expandable basket can be suitable for placement in, for example, a cardiac cavity. For larger body cavities, the expandable basket can have larger dimensions, for example, 30 mm to 150 mm, or 40 mm to 120 mm, or 50 mm to 100 mm. In other situations, a fully expanded expandable basket with smaller dimensions may be suitable for smaller body cavities. Such smaller expandable baskets may have dimensions in the fully expanded state of, for example, 3 mm to 25 mm, or 5 mm to 15 mm, or 7 mm to 10 mm.

[0107] In some embodiments, rather than the filaments (415) braided into the braided mesh (413) being cut adjacent to the distal portion of the expandable basket (409), the filaments (415) can be bent at the distal portion and attached adjacent to the distal portion of the inner elongate shaft to form a terminal assembly. The bent filaments can then be directed back toward the expandable basket (409) or the outer elongate shaft, where they can terminate. Figure 6A shows an expandable basket (409) with bent filaments at its distal portion (603) in more detail.

[0108] Expandable baskets made from braided mesh have an advantage over prior art solutions with non-braided struts in that they have higher mechanical stability while using relatively thin filaments. Having more filaments in the structure can also allow for the use of more electrodes. The electrodes placed on the filaments can also be more optimally distributed, meaning, for example, that they can be placed closer together or desired patterns can be created in the expandable basket. Another advantage of expandable baskets made from braided mesh is the higher mechanical stability of the structure, which can ensure a stable and predictable distance between electrodes.

[0109] The braided mesh may be heat-treated to ensure deformation of the filaments and fixation of such deformation. Such deformed filaments then ensure that the filament intersections (points where filaments cross each other) remain relatively stable over the length of the filaments during expansion and collapse of the basket assembly (expandable basket). This means that the filament intersections remain relatively the same over long distances of the filaments in the collapsed and fully expanded states of the basket assembly (expandable basket). What changes is the mutual angle of the specific filaments forming the intersections (e.g., from about 2 degrees to 178 degrees, or vice versa). While some small longitudinal movements of the intersections may not be completely avoided by this process, they are limited to a degree that does not impair the dimensions and / or mechanical stability of the braided mesh. This feature may then enable, for example, the placement of electrodes at the filament intersections and / or ensure the electrodes' stable, predictable, and desired mutual positions and / or distances.

[0110] Further structural stability of an expandable basket made from a braided mesh can be achieved, for example, by joining certain filaments (contained in the braided mesh) together. The filaments can be joined to each other, for example, at their intersections. An exemplary solution can be seen in FIG. 20. The joints (2001) can be fixed (not allowing any mutual movement of the filaments at the joint) or interacting (allowing some kind of mutual movement of the filaments at the joint). Joining can be achieved, for example, by gluing, welding, laminating, bonding, tying (e.g., with some kind of string), or melting. Another option would be to tie the filaments together, for example, by a ring structure or crimping. If the ring structure is made of a conductive material (e.g., metal), it can also function as an electrode. The same applies to crimping. Metal connectors can also function as electrodes.

[0111] A structure adapted to join two filaments may already be included on the filament even before braiding. In examples where at least one filament (415) is produced by a molding process, such as an injection molding process, the filament (415) may include at least one region where the filament splits and / or at least one region where additional loops (2201) on the filament are formed during the molding process, as seen in Figures 22 and 23. Such at least one split region and / or additional loops (2201) may be created, for example, at or adjacent to at least one filament crossover region (2202), which is a region of the filament that intersects with another filament at an intersection (2301) of the braided mesh. A split or loop (2201) on a first filament (415) included in the cross-point (2301) can be adapted for insertion of a second filament (415) included in the cross-point (2301), thus functioning to facilitate joining (securing) the two filaments (415) together at the cross-point (2301). Such cross-points (2301) where the filaments (415) are secured by a loop (2201) or split can have similar properties to cross-points joined by, for example, tying, but without the need for a tying step.

[0112] In an example, if a first filament included in an intersection includes a loop in and / or adjacent to the intersection region involved in the intersection, the second filament included in the intersection does not include a loop in and / or adjacent to the intersection region involved in this particular intersection, meaning that there can be a maximum of one loop at any intersection. The length of the loop in and / or adjacent to the intersection region on the first filament at the intersection (the length from the connection point with the first filament to the connection point with the second filament) can be selected according to the diameter of the second filament included in the intersection (the other filament must fit into the loop, but the loop should not be too loose around the other filament), for example, 0.5 mm to 10 mm, 1 mm to 7 mm, or 2 mm to 5 mm. The cross-sectional diameter of the loop can be, for example, 0.1 mm to 1 mm, 0.15 mm to 0.7 mm, or 0.2 mm to 0.5 mm.

[0113] All of the intersections included in the expandable basket may be joined, or only some of the intersections may be joined and the remaining intersections may not be joined.

[0114] In another example, the expandable basket can be made by a molding process, such as an injection molding process. The mesh of the expandable basket may not be braided in this example, but may be made from a molded structure. There may be several options for how to make the expandable basket by molding.

[0115] The expandable basket can be fabricated, for example, by at least one formed mesh in the form of a two-dimensional (flat, planar) structure (planar formed mesh) (2401), as shown in FIG. 24a. The at least one planar formed mesh (2401) is configured to be formed into a three-dimensional shape after forming. After forming, the at least one planar formed mesh can be removed from the mold and bent, for example, around a central longitudinal axis (203), into the shape of a tube, as shown in FIG. 24b. FIG. 24c shows an example of creating an expandable basket using multiple planar formed meshes. Each of the formed meshes (2401), in this example, alone forms only a portion of the intended tube (a portion of the circumference of the intended tube) and can be bent into a shape that, when assembled, forms a complete tube. The edges (2402) of the formed meshes are then joined together (e.g., by welding, crimping, gluing, tying, etc.) to create a tubular structure. The distal portions (2403) of the tubular structures can then be mated and optionally secured to the distal portion of the inner elongate shaft to create the terminal assembly, and thus the expandable basket. The proximal portion (2404) of the tubular structures can be coupled to the distal end of the outer elongate shaft.

[0116] In another example, the expandable basket can be made from a molded mesh that has already been formed into a three-dimensional structure. Figure 25a shows an example of such a structure, which can be, for example, a tubular molded mesh structure (2501). In this example, the step of bending the two-dimensional flat molded mesh can be omitted, but the tubular molded mesh structure is already created in the mold. Further steps are similar to the previous example. The distal portion (2403) of the tubular molded mesh structure (2501) can be paired and joined, and optionally secured, to the distal portion of the inner elongate shaft, thus creating the terminal assembly and, therefore, the expandable basket. The proximal portion (2404) of the tubular molded mesh structure (2501) can be joined to the distal end of the outer elongate shaft.

[0117] In a further example, which can be seen in Figure 25b, the expandable basket (409) can be molded in a single step. In this particular example, the expandable basket is made directly by a molding process with the distal portion (2502) of the expandable basket already molded therewith, thus creating at least a portion of the terminal assembly in a single step with the molding of the remaining portions of the expandable basket. The molded distal portion (2502) of the expandable basket (409) can then be coupled to the distal end of the inner elongate shaft, and the proximal portion (2503) can be coupled to the distal end of the outer elongate shaft.

[0118] A shaped mesh formed as a three-dimensional structure can be a shape other than tubular, for example, it can be formed into the shape of an expandable basket in one of its expanded states.

[0119] The formed mesh formed as a three-dimensional structure need not be formed as a complete structure, but it is possible to form several three-dimensional sections of the formed mesh and then join the sections together. The three-dimensional sections can, for example, be made up of only a portion of the intended structure (e.g., a portion of the circumference of one tube or basket in an expanded state) and, when paired and joined, create a complete structure.

[0120] In the example of an expandable basket made from a molded mesh, electrodes, conductive wires, and / or other structures (e.g., tubes for forming lumens, reinforcing struts, etc.) may be placed in a mold before molding and can be overmolded during molding of the molded mesh. The structures can be fully overmolded, meaning that they are completely inside the molded mesh and do not reach the surface of the molded mesh, and / or partially, e.g., at least a portion of their surface is exposed at the surface of the molded mesh. For example, electrodes can be partially overmolded when at least a portion of their surface is exposed at the surface of the molded mesh. However, the structures do not need to be overmolded; at least a portion of them can be added to the molded mesh after the molding process.

[0121] The molded mesh can be made from a polymer or thermoplastic elastomer such as, for example, nylon, fluorinated ethylene propylene (FEP), polyethylene (PE), PEBA, PEEK, polyimide (PI), polypropylene (PP), PTFE, polyurethane (PU), polyethylene terephthalate (PET), or silicone.

[0122] The particular openings (mesh, interstices) within the braid or shaped mesh need not be uniform in size; rather, the size of the particular openings may vary. The size may increase, for example, from the distal and proximal portions of the expandable basket (which may be smallest) to the middle portion of the expandable basket (which may be largest). In other words, the dimensions of the openings in the central body portion of the basket assembly may be larger than the dimensions of the openings in the proximal and distal body portions of the basket assembly. The dimensions may increase, for example, linearly or exponentially. The circumferences of the openings in the proximal and distal body portions may be, for example, between 1 mm and 40 mm, while the circumferences of the openings in the central body portion may be, for example, between 5 mm and 80 mm. The number of rows of openings forming the complete braid or shaped mesh of the expandable basket may be between 4 and 40.

[0123] The ratio of the circumference of the smallest opening to the circumference of the largest opening in the expandable basket can be 100:101 to 1:80, or 20:21 to 1:50, or 10:11 to 1:40. The number of rows of openings can be counted from the first complete opening at the attachment of the proximal portion of the expandable basket adjacent the distal end of the outer elongate shaft to the last opening at the distal portion of the basket assembly terminated by the terminal assembly. The total number of openings in the braided or molded mesh forming the expandable basket (total number of openings in the expandable basket) can be 12 to 1000, or 16 to 500, or 24 to 259, or 32 to 128.

[0124] Two or more filaments forming a braided or shaped mesh, and thus an expandable basket, can be merged or joined together at their proximal and / or distal ends to form a merged structure (2101) in the proximal and / or distal portions of the expandable basket, as shown schematically in FIG. 21 . Such a solution can reduce the number of filaments in the proximal and / or distal portions of the expandable basket. Reducing the number of filaments entering related structures, such as the proximal portion of the expandable basket adjacent to the distal end of the outer elongate shaft and / or the proximal portion of the basket assembly, which may include attachments to the distal portion of the basket assembly, which may include a terminal assembly, can reduce the complexity and / or mechanical stability of those structures and thus the entire basket assembly. Because the number of components in a structure with a reduced number of filaments is reduced, it may even help reduce the risk of ablation procedures. With regard to filament length, the merged structure in the proximal or distal portion of the filament can account for 1% to 30%, or 3% to 20%, or 5% to 15% of the total length of the filaments included in the expandable basket. As mentioned above, the filaments can be merged at their distal or proximal ends, or both. When filaments are merged at both ends, the merged lengths can be the same at both ends, or they can be different. The merged portions of the filaments at either the proximal or distal end of the basket can account for 1% to 35%, 4% to 25%, or 6% to 20% of the length of the expandable basket in its collapsed configuration. The filaments can be merged, for example, by bonding, welding, laminating, gluing, tying, or melting. Another option is to join the filaments together, for example, by some kind of tubular structure or by crimping. The tubular structure can be, for example, a tube made of metal or polymer, or a thermoplastic tube with a lumen. In this case, the ends of the filaments are threaded through the lumen of the tube and secured therein (e.g., by bonding, welding, laminating, gluing, tying, melting, or swaging), thus joining them to each other.Another option may be the use of a multi-lumen tube made of metal or polymer or thermoplastic, with each end of each filament to be joined being threaded through a separate (its own) lumen of the multi-lumen tube and secured therein (e.g., by gluing, welding, laminating, bonding, bundling, melting or swaging), and thus joined together.

[0125] In examples with filaments (415) manufactured by a molding process such as injection molding, at least two filaments (415) can be molded as a single filament, braided into a braided mesh, and then merged together at their proximal and / or distal ends to form the merged structure (2101). However, at least two filaments (415) can be molded at once, such that at least one of the merged structures (2101) (either proximal or distal) can already be formed during the molding process. An example of a filament (415) and merged structure (2101) made by a molding process can be seen in FIG. 26. The filaments (415) containing the already formed merged structure (2101) can then be braided into a braided mesh, avoiding at least one step of filament merging after braiding. Ends of the filaments (415) that are not yet merged from the molding process can merge together and / or with other different filaments after the braiding process.

[0126] The filaments may be made from electrically insulating, non-conductive materials, such as nylon, fluorinated ethylene propylene (FEP), polyethylene (PE), PEBA, PEEK, polyimide (PI), polypropylene (PP), PTFE, polyurethane (PU), polyethylene terephthalate (PET), or polymers or thermoplastic elastomers, such as silicone. The material may be further reinforced, for example, with glass fibers. The cross-section of the filaments may be circular, or other cross-sectional shapes are possible, for example, but not limited to, oval, circular, semicircular, rectangular, square, flat, or star-shaped. The filaments (415) may be formed from a tube having an at least partially hollow structure with a lumen (601), as seen in FIG. 6B, for example. Some or all of the filaments (415) may be hollow along their entire length, or, for example, the lumen (601) may be present only along a portion of the length of one or more filaments (415). Another embodiment may include a braided mesh (413) that includes a first subset of filaments (415) that include a lumen (601) and another subset of filaments (415) that do not have a lumen, or none of the filaments may have a lumen.

[0127] In another example, the filament can be fabricated by a molding process, such as an injection molding process. The electrodes (109), e.g., the conductive wires (417) connected to the electrodes (109), and / or other components (e.g., tubes for creating lumens, reinforcing struts (2702), other wires, etc.) can be pre-positioned in the mold (2701) before molding, or can be overmolded during the shaping of the filament, as shown in FIG. 27 . Components can be fully overmolded, meaning they do not reach the surface of the filament (are not exposed on the surface of the filament), are completely inside the shaped filament, and / or can be partially overmolded, e.g., when at least a portion of their surface is exposed on the surface of the shaped filament. For example, electrodes can be partially overmolded when at least a portion of their surface is exposed on the surface of the shaped filament. However, structures need not be overmolded; at least a portion of them can be added to the filament, and thus to the subsequent braided mesh, after the shaping process.

[0128] Filaments made from electrically insulated tubes with a hollow structure (cavity) can have drawbacks, for example, when an electrode, such as a tube, is placed on the filament and a wire connected to the electrode is guided inside the filament's lumen. A small opening in the filament wall usually facilitates the wire's transition through the filament wall. This small opening must be sealed, for example, to prevent blood or other fluids from reaching the inside of the filament. If the electrode is a ring electrode placed around the filament, the seal can be between the filament and the electrode. Typically, such a seal is achieved by adhesive placed in the area between the edge of the electrode and the filament on which the electrode is placed. The adhesive ensures a seal between the electrode and the filament. Another advantage of such a solution is that the adhesive on the edge of the electrode adds rigidity to the filament immediately adjacent to the electrode, ensuring that if the filament needs to bend in the area where the electrode is placed, the filament bends further away from the edge of the electrode, preventing exposure of the electrode's edge. Electrodes can have sharp edges, and exposing such sharp edges could, for example, cause harm to the patient. A drawback of the solution of ring electrodes placed on a tubular filament and sealed with adhesive is that the seal adds additional material, which means that the diameter of the filament increases where the adhesive is applied to the filament, which can be problematic for catheters with a large number of filaments. Another problem with the solution of applying adhesive to seal the electrode from the filament is that the adhesive can peel off, which can cause portions of the adhesive to become loose and potentially cause harm to the patient. This problem can be solved, for example, by filaments manufactured by a molding process, or in further examples, by filaments such as

[0129] In another example, the filament (415) may take the form of an at least partially hollow structure, including a tube made of a non-conductive material, such as a thermoplastic. Exemplary cross sections of such a filament (415) can be seen in Figures 31a-31c. A filament (415) including an electrode (109), e.g., a ring electrode, may include at least two tubes (3100) that may be joined together at the location where the electrode (109) is disposed on the filament (415). The tubes (3100) may be made of a material with a melting point, e.g., a material with a melting point lower than that of the other structures of the filament, e.g., a thermoplastic. The tube joint may include a molten material (3101), which may originate from at least one of the tubes (3100). The molten material (3101) fills the lumen of the electrode (109) and can seal the electrode and / or conductive wire (417) connected to the electrode, or another structure leading from the lumen of the filament to the electrode (109), or any other structure leading to the lumen of the filament, ensuring a secure connection between the tubes. The filament can include a cord (3102) that can be longitudinally disposed inside the lumen of the filament and can provide an uninterrupted connection, at least in the region where the electrode (109) is disposed on the filament (415) and thus the tubes (3100) are connected to each other. The cord (3102) can function as reinforcement for the filament.

[0130] The manufacturing process for a filament including at least two tubes described in the previous paragraph can include the steps shown in Figures 31a-31c. In the first step shown in Figure 31a, the tubes (3100) and electrodes (109) are placed on a cord (3102) so that the electrode (109) is positioned between the tubes, thus creating an assembly. A conductive wire (417) connected to the electrode (109) is routed into the lumen of one of the tubes (3100). In the next step, the entire assembly is heated to at least the melting temperature of the material from which the tubes (3100) are made. The tubes (3100) melt, and molten material from the end of the tube adjacent to the electrode flows into and fills the lumen of the electrode. In the next step, the assembly is cooled to a temperature below the melting temperature of the material from which the tubes (3100) are made. The results of this step can be seen in Figures 31b and / or 31c.

[0131] The exemplary filament (415) shown in FIGS. 31a-31c may include other structures, particularly at least one ring (3103). The ring may be made of a different material than the tube (3100). In particular, the melting point of the ring (3103) material may be higher than that of the tube (3100), and the deflection point of the ring (3103) material may be approximately the same as that of the tube (3100). The ring may be located on the tube, particularly at the end of the tube adjacent to the electrode (109). This can serve as an additional sealing, surface smoothing, and reinforcing element at the transition between the edge of the electrode (107) and the tube (3001). This can prevent overflow of the tube material onto the electrode during the manufacturing process. The ring can also assist in the bending point of the filament. When the filament is bent, it can help move the bending point away from the electrode at the sharpest angle, which can be beneficial, for example, to prevent exposure of the electrode's sharp edges. The length L of the ring can be 0.1 mm to 10 mm, or 0.2 mm to 5 mm, or 0.5 mm to 4 mm, or 0.7 to 2.5 mm. The filament may include one ring adjacent one side of the electrode, or it may include at least two rings, for example, adjacent both sides of the electrode.

[0132] The inner diameter of the rings (3103) before the manufacturing process may be the same as or larger than the outer diameter of the tube (3100) they have before the manufacturing process. In the first step of the manufacturing process, as shown in FIG. 31a, the ring (3103) can be placed on the tube (3100), specifically on the end of the tube adjacent to the electrode (109), and the tube (3100) with the electrode (109) is placed on the cord (3102) so that the electrode (109) is placed between the tube (3100) with the ring (3103) to form an assembly. In the next step, the entire assembly is heated to at least the melting temperature of the material from which the tube (3100) is made and the deflection temperature of the material from which the ring (3103) is made. The tube (3100) melts, and molten material from the end of the tube adjacent to the electrode flows into and fills the lumen of the electrode, while the ring (3103) shrinks. The softened ring (3103) should shrink until its outer diameter reaches the same size as the outer diameter of the electrode (109), or between the same size as the outer diameter of the electrode (109) and minus 10% of the outer diameter of the electrode (109), or between minus 0.1% of the outer diameter of the electrode (109) and minus 7% of the outer diameter of the electrode (109), or between minus 0.2% of the outer diameter of the electrode (109) and minus 5% of the outer diameter of the electrode (109). Such an amount of shrinkage prevents the material from which the ring (3103) is made from from melting onto the electrode in subsequent steps, which could lead to potential insulation issues or delamination of such melted material on the electrode during use. The results of this step can be seen in Figure 31b. In the next step, the assembly is further heated to the melting temperature of the material from which the ring (3103) is to be formed. As shown in Figure 31c, the material of the ring (3103) melts and bonds with the material of the tube (3100). In a next step, the assembly is cooled to at least the melting temperature of the material from which the tube (3100) is made.

[0133] Due to shrinkage of the molten material of the tube (3100) and due to some of the material filling the electrode lumen during the manufacturing process, the outer diameter of the tube (3100) prior to the manufacturing process may be larger than the outer diameter of the electrode. This may be, for example, 1% to 60%, or 3% to 50%, or 5% to 40%, or 10% to 35% larger. The materials of the tube (3100) and ring (3103) may be, for example, thermoplastics with two different melting temperatures, such as nylon. The materials may be selected so that the melting point of the ring (3103) material is higher than the melting point of the tube (3100) material and the deflection point of the ring (3103) material is approximately the same as the melting point of the tube (3100) material.

[0134] The diameter of the filaments in the braided or formed mesh can be 0.2 mm to 1 mm, or 0.4 mm to 0.8 mm, or 0.5 mm to 0.7 mm. The number of filaments braided into the braided mesh forming the expandable basket can vary from 5 to 150, or 10 to 60, or 15 to 50, or 16 to 32. The filaments produced by the forming process can have several specific aspects. For example, the diameter of the filament need not be uniform throughout its entire length but may vary along its length. For example, the filament may have a different (e.g., reduced) diameter in at least one intersection region compared to the remainder of the filament. In the specific example of an intersection of two filaments, at least one of the filaments forming the intersection may be reduced in diameter and / or cross-sectional area adjacent to and / or involved in the intersection. In examples, when the diameter of a filament is reduced in a specific region, it may be reduced by, for example, 0.1% to 90%, or 0.5% to 75%, or 1% to 60% compared to the diameter of the unreduced filament. In instances where the cross-sectional area is reduced in a particular region, it may be reduced by an amount between 0.1% and 90%, or between 0.5% and 75%, or between 1% and 60% compared to the unreduced cross-sectional area.

[0135] The reduction in the filaments in and / or adjacent to the intersection region can help mechanically stabilize the braided mesh, and therefore the expandable basket, by providing more stable intersections and / or can help reduce the maximum diameter of the collapsed expandable basket. The reduced diameter filaments in and / or adjacent to the intersection region can ensure that the filament intersections remain relatively stable across the length of the filaments as the basket assembly (expandable basket) expands and collapses. This means that the filament intersections remain relatively the same across the length of the filaments in the collapsed and fully expanded states of the basket assembly (expandable basket). What changes is the angle between the specific filaments forming the intersection (e.g., from about 2 degrees to 178 degrees, or vice versa). While some small longitudinal movements of the intersections may not be completely avoided, they are limited to a degree that does not compromise the dimensions and / or mechanical stability of the braided mesh. This feature, for example, can then enable the placement of electrodes at the filament intersections and / or ensure a stable, predictable, and desired mutual position and / or distance of the electrodes.

[0136] In another embodiment, the filaments produced by the molding process can have variable cross-sectional shapes. This can be advantageous, for example, at filament intersections, where a different cross-sectional shape of at least one of the filaments included in the intersection can help stabilize the intersection and / or reduce the maximum diameter of the expandable basket in a collapsed configuration. The cross-sectional shape used at and / or adjacent to the intersection region of the filaments included in the filament intersection can be, for example, semicircular, rectangular, flat, elliptical, or oval, while the cross-sections of the remainder of the filaments can be different, for example, circular. If the cross-sections of the filaments at and / or adjacent to the intersection region include flat or planar sides, the flat or planar sides can be in contact with other filaments forming the intersection.

[0137] Combinations of varying cross-sectional areas and varying diameters of the filaments are also possible. For example, the filaments can have different cross-sections and different (e.g., reduced) diameters at and / or adjacent to the intersection regions, which can again help stabilize the braided mesh, and thus the expandable basket, and reduce the maximum diameter of the expandable basket in the collapsed configuration. The maximum diameter of the expandable basket in the collapsed configuration can be reduced by, for example, 0.01% to 50%, or 0.05% to 30%, or 0.1% to 15%.

[0138] Variable diameters and / or cross-sections may be used not only in and / or adjacent to filament crossover regions, but also in different regions of the filament. For example, reduced diameters and / or cross-section changes may allow for the creation of weaker and / or more rigid regions of the filament, e.g., to create living hinges during the filament shaping process.

[0139] In another example, the shaped filament need not be straight, but may be prefabricated with at least one bend or curve (2601). The bend and / or curve (2601) may be located, for example, at and / or adjacent to at least one intersection region of the filament, or, for example, adjacent to the proximal or distal end of the filament. An example of such a solution is seen in FIG. 26. The prefabricated curve (2601) can, for example, serve to further stabilize the braided mesh and, therefore, the expandable basket. The filament may be prefabricated such that post-braiding thermal stabilization of the braided mesh is not required.

[0140] In further embodiments, the filament can be shaped to include at least one region where the filament splits and / or at least one region where an additional loop (2201) on the filament (415) is formed during the shaping process. Such at least one split region and / or additional loop (2201) may be formed, for example, at and / or adjacent to at least one filament crossover region (2202) and may function, for example, as a support at at least one intersection of two filaments (415) after the filaments (415) are braided into a braided mesh. In a further example, the filament can include electrodes inside the split (e.g., inside the region bounded by the beginning and end of the filament split) and / or inside the filament loop region (2203) bounded by the first connection point (2204) of the loop (2201) to the filament (415) and the second connection point (2204) of the loop (2201) to the filament (415), as seen in FIG. 22 .

[0141] The filament intersection region is the region of the filament involved in the intersection in the braided mesh structure. In some cases, at least one electrode may be disposed in and / or adjacent to the filament intersection region. If an electrode is disposed in and / or adjacent to the intersection region of a first filament included in a particular intersection, the second filament included in this intersection may not include an electrode in and / or adjacent to the intersection region of this particular intersection. This means that there may be a maximum of one electrode at any intersection of the braided mesh, and therefore the expandable basket. In a further embodiment where an intersection includes an electrode, it may be included in and / or adjacent to the filament intersection region further laterally away from the longitudinal axis at this particular intersection, meaning that the electrode is disposed on the periphery of the expandable basket.

[0142] In examples involving shaped filaments, such shaped filaments can have a different diameter and / or cross-section in at least one intersection region than the remainder of the filament, as previously described. In one particular example, if an electrode is included at an intersection, a first filament including the electrode can have a cross-section corresponding to the cross-section of the electrode in the intersection region (e.g., a circular cross-section) and can include a loop at or adjacent to the intersection region, and a second filament at this intersection can have, for example, a smaller diameter and / or a different cross-section than the remainder of the filament (e.g., it can have a flat, rectangular, oval, or semicircular cross-section in the intersection region and a circular cross-section in another region).

[0143] However, this does not mean that a filament with an electrode at or adjacent to the intersection region cannot have a different diameter or a different cross-section at the intersection region than the remainder of the filament. For example, an electrode included on a filament can have a different diameter or a different cross-section than the remainder of the filament.

[0144] There are further options for increasing the mechanical stability of the filament. One of them is the use of multilayer walls. The walls of the filament can, for example, contain two or more layers of material. Materials with different properties can be used in combination to result in a more mechanically stable wall and therefore a more mechanically stable filament. Such combinations can use layers made of different materials, for example, from the group of polymers or thermoplastics, such as nylon, fluorinated ethylene propylene (FEP), polyethylene (PE), PEBA, PEEK, polyimide (PI), polypropylene (PP), PTFE, polyurethane (PU), polyethylene terephthalate (PET), or silicone. Another possible option is the use of layers made of the same type of material, but with different subgroups of materials with different properties for each layer. The materials used for certain layers can be further reinforced, for example, with glass fibers.

[0145] In another embodiment, the filament can be further mechanically reinforced, for example, by inserting a mechanical support into the filament lumen. Such a mechanical support can be, for example, in the form of a strut disposed in the filament lumen. The strut can be disposed within the entire length of the filament or within the entire length of the filament lumen if the filament does not have a lumen along its entire length. Another possible option is to dispose the strut only along a portion of the entire length of the lumen, thus reinforcing a portion of the filament with struts and leaving another portion without strut reinforcement. The strut can be made, for example, of nitinol, or, for example, of an electrically insulating layer, such as polyamide (PA), polyimide (PI), or PTFE. Other possible materials suitable for the struts can be polymers or thermoplastics, such as nylon, fluorinated ethylene propylene (FEP), polyethylene (PE), PEBA, PEEK, polyimide (PI), polypropylene (PP), PTFE, polyurethane (PU), polyethylene terephthalate (PET), or silicone.

[0146] In examples with a molded filament, at least one reinforcing strut (2702) can be placed in the mold (2701) and overmolded. In this example, the strut (2702) must be made from a material with a higher melting point than the filament. The at least one strut (2702) can be placed over the entire length of the filament or only a portion of the length of the filament, thus leaving some of the filament reinforced with the strut and other portions without strut reinforcement. An example of a strut already placed in the mold can be seen in FIG. 27.

[0147] Yet another suitable option for further reinforcing the filament is to fill at least a portion of the lumen of the filament with an adhesive or a molten polymer or thermoplastic material.

[0148] The braided mesh may then be configured such that all of the filaments contained in the braided mesh are reinforced, or such that only a portion of the filaments contained in the braided mesh include reinforcement, while another portion of the filaments may not include reinforcement.

[0149] At least one of the filaments forming the braided mesh can include at least one location where the structure of the filament is locally mechanically weaker than the rest of the filament. Such a location can form a so-called living hinge (2103), as shown schematically in FIG. 21 . A living hinge can be useful for defining a more or less precise location where the filament included in the braided mesh, and therefore the expandable basket, bends more easily, forming a smaller radius (or a more direct kink) than a filament without such a living hinge. This can further help define a more predictable shape of the deployed expandable basket in at least one of the deployed positions. Establishing such a living hinge in the filament can include thinning or cutting a portion of the filament. Thinning can be achieved, for example, by squeezing or thermoforming a specific location of the filament. Thinning can occur around the entire circumference of the filament or only partially. A partially asymmetric thinning can be advantageous, since the hinge thus formed can define a specific direction in which the filament is more likely to bend compared to other directions. In one example of an expandable basket, living hinges formed in the filaments can allow the filaments, and therefore the braided mesh, to bend more easily, for example, radially from the central longitudinal axis of the catheter. For example, living hinges that create a smaller radius or twist in the filaments in the region of the distal body portion (421) of the basket assembly body or the terminal assembly can help shape the expandable basket (basket assembly body) in a region distal to a plane that intersects with the basket assembly at its largest diameter (in one of its expanded configurations), so that at least a portion of the distal portion of the expandable basket (region of the distal body portion) can form a larger angle (radially from the elongated axis) compared to the proximal portion of the basket (region of the proximal body portion).In extreme cases, the distal portion of the expandable basket (region of the distal body portion) can form an angle of 90° or more (radially from the elongate axis) such that at least a portion of the expandable basket containing the electrodes is the longitudinally most distal portion of the catheter and achieves the expanded state without any other portion (e.g., the contact assembly) protruding more distally. Such a configuration can be advantageous, for example, in ablation of a relatively flat treatment site.

[0150] In instances where the expandable basket is formed from a formed mesh or where it includes filaments formed by a forming process, the living hinge may be formed directly during the forming of the formed mesh or shaped filament, for example, by at least one of a reduction in diameter of a portion of the formed mesh or filament and a change in cross-section of a portion of the formed mesh or filament.

[0151] At least one living hinge, as described in the previous paragraph, may be included in at least a portion of the braided mesh where the filaments are merged together (in a merged structure). In this case, the living hinge is a location on the merged structure that is locally mechanically weaker than the rest of the merged structure and may be created, for example, by thinning or cutting the merged structure after merging. Another option for establishing a living hinge in the merged structure, particularly when the merged structure includes a polymer tube and filaments are merged into the lumen of the tube or into multiple lumens of a multi-lumen tube, is to pre-thin or pre-cut the polymer tube before inserting the filaments. Such pre-thinning of the tube can be achieved, for example, by squeezing, thermoforming, or molding, e.g., injection molding.

[0152] The living hinges can be formed in the distal, central, and / or proximal body portions of the basket assembly body. For example, if they are located in the proximal body portion, they can be located in a proximal region that is 0% to 20%, 0% to 15%, or 0% to 10% of the length of the folded basket. If they are located in the distal body portion, they can be located in a distal region that is 0% to 20%, 0% to 15%, or 0% to 10% of the length of the folded basket. They may also be part of the terminal assembly. If the hinge is located in the central body portion, it can be located on a plane that intersects the basket assembly, distal to the maximum diameter, or -20% to +20%, -10% to +10%, or -5% to +5% of this plane or the center of the folded basket.

[0153] The expandable basket can include one or more electrodes or a set of electrodes. The electrodes can be configured for at least one of generating an electric field for ablation of tissue or acquiring or transmitting electrical or other signals, such as signals for tissue mapping, ECG monitoring, impedance measurement, and / or detecting contact with tissue. Another function of the electrodes can be to serve as markers for X-rays. Electrodes can be coupled to specific filaments of the expandable basket. Electrodes can be disposed on each filament or on only a portion of the filaments. Each electrode-containing filament can include one or more electrodes, for example, 1 to 15, 1 to 10, 1 to 6, or 1 to 3 electrodes. The electrodes can be of one type or different types. The total number of electrodes disposed on the expandable basket can be 1 to 200, 5 to 100, 10 to 50, 15 to 40, or 20 to 35. The spatial distance between the electrodes in the fully expanded configuration of the expandable basket can be between 0.1 mm and 15 mm, or between 0.5 mm and 10 mm, or between 1 mm and 6 mm, or between 2 mm and 4 mm.

[0154] The electrodes may operate individually or in pairs or groups, or some of the electrodes may operate individually and some may operate in pairs or groups.

[0155] In examples, electrodes may be positioned at regions where filaments cross one another (filament crossing points). Such locations may be advantageous due to the ability to maintain a more stable distance between electrodes during different configurations of the expandable basket, and such configurations may also advantageously prevent undesired contact between electrodes, particularly when the expandable basket is not in a fully expanded configuration.

[0156] All of the electrodes contained in the expandable basket may be located at the filament crossings, or only some of the electrodes may be located at the filament crossings and some of the electrodes may be located elsewhere.

[0157] Each filament may also contain one or different types of electrodes, or different filaments may house different types of electrodes. Different types of electrodes can be understood as electrodes with different functions, such as ablation electrodes and measurement electrodes, or physically different electrodes, such as those with different shapes, sizes, designs, or materials, or as a combination of different types of electrodes with different functional and physical properties. For example, in a configuration with ring-shaped electrodes arranged on a filament, all electrodes may have the same diameter but different lengths, so that there may be, for example, two or more groups of such electrodes, each group having a different length. The number of electrodes in each group may be the same or different. In extreme cases, each electrode in the expandable basket may have a different length. In a configuration with ring-shaped electrodes, such electrodes may have a diameter of 0.2 mm to 3 mm, or 0.4 mm to 2 mm, or 0.5 mm to 1 mm, and a length of 0.1 mm to 10 mm, or 0.2 mm to 8 mm, or 0.3 mm to 6 mm, or 0.4 mm to 4 mm.

[0158] In one example, there may be a first group of 5 to 20 shorter electrodes, e.g., having a length of 0.3 mm to 3 mm, and a second group of 5 to 30 electrodes, which may be longer, e.g., having a length of 0.6 mm to 4 mm. Advantageously, electrodes from the first group may be used for at least one type of measurement, e.g., intracardiac ECG (EGM) measurement, or ablation, and electrodes from the second group may be used for ablation, either independently or in combination with electrodes from the first group.

[0159] Electrodes can be positioned on the body of the basket assembly. For example, electrodes can be positioned on the central or distal body portion, and in some cases, electrodes can even be positioned on the proximal body portion. Other electrodes can be positioned on or within the outer elongate shaft, inner elongate shaft, catheter distal tip, or terminal assembly. In configurations where electrodes are positioned on the elongate shaft, distal tip, or terminal assembly and ring electrodes are used, they can have a diameter of 0.2 mm to 10 mm, or 0.5 mm to 8 mm, or 1 mm to 6 mm, or 2 mm to 5 mm, and a length of 0.1 mm to 20 mm, or 0.2 mm to 15 mm, or 0.3 mm to 12 mm, or 0.4 mm to 10 mm.

[0160] The layout of the electrodes on the expandable basket can ensure a continuous, eg, circular, ablation area while the expandable basket is in the expanded position, and a pattern can be created.

[0161] For example, the layout of the electrodes in the expandable basket can ensure a continuous circular ablation area, and patterns can also be created, even while the expandable basket is held in various expanded positions between the fully collapsed position and the fully expanded position.

[0162] Additional electrodes, such as those located on or within the outer elongate shaft, inner elongate shaft, catheter distal tip, or terminal assembly, may be part of the pattern or may be operated independently of the other electrodes. For example, electrodes in the region of the distal tip or terminal assembly of the catheter may be used for point ablation. There may be special, dedicated electrodes in the region of the distal tip or terminal assembly, or, for example, metal components of the terminal assembly may function as electrodes, or a combination thereof may be possible.

[0163] The pattern (701) generated by the electrodes (109) may be, for example, a circular pattern in space around the central longitudinal axis (203) when the expandable basket (409) is in one of its expanded configurations, as seen at least in FIG. 7A. Other two-dimensional or three-dimensional patterns generated by the electrodes (109) are also possible. The pattern (701) may or may not be centered around the central longitudinal axis (203). The pattern (701) may have different shapes, including, but not limited to, circles, ellipses, squares, rectangles, polygons, planes, etc., or the arrangement of the electrodes (109) on the expandable basket may be irregular. For example, there may be one pattern (701) in one plane, more patterns (701) in one plane, or more patterns (701) in different planes.

[0164] The pattern generated by the electrodes can be disposed on the basket assembly body, particularly the distal, central, or proximal body portions, as shown in FIG. 7B. The pattern may extend through two or more of these portions. For example, for treatment of a flat treatment site located distally from the basket assembly, the electrode pattern may be advantageously disposed on the distal portion of the basket assembly. In particular, the pattern may be disposed on a portion of the basket assembly surrounded by a region that forms an angle (703) of 0° to 90° with respect to the central axis (203) at the center of a plane (425) that intersects the basket assembly at the portion of the basket assembly having the largest diameter (in one of the expanded configurations). In some configurations, the pattern may be disposed partially on the distal portion of the basket assembly body and partially on the central portion of the basket assembly body. In some configurations, the pattern may be disposed on a section of the basket assembly surrounded by a region that forms an angle (705) of 0° to 120° with respect to the central axis (203) at the center of the plane (425). Such pattern placement may be particularly advantageous for treatment of a blood vessel opening, such as the ostium of a pulmonary vein. In situations where the treatment site has a tubular shape, the pattern may be disposed in the intermediate portion of the basket assembly, particularly in the portion of the basket assembly bounded by a region that forms an angle (707) of 45° to 135° with respect to the central axis (203) at the center of the plane (425). When a flat treatment site is disposed proximal to the basket assembly, e.g., the septum, the electrode pattern may be disposed in the proximal body portion of the basket assembly, or partially in the proximal body portion and partially in the central body portion, particularly in the portion of the basket assembly bounded by a region that forms an angle (709) of 90° to 180° with respect to the central axis (203) at the center of the plane (425). Optionally, electrodes may be disposed in all portions of the basket assembly, thus creating patterns in all portions and selecting only those patterns necessary or optimal for performing a particular treatment.

[0165] A particular pattern can be created using all of the electrodes in the expandable basket, or only a portion of the electrodes. The pattern can have different numbers of electrodes in various expanded positions between the fully collapsed and fully expanded positions of the expandable basket. Adjacent electrodes in the pattern can have a distance between each other of, for example, 0.1 mm to 15 mm, 0.5 mm to 10 mm, 1 mm to 6 mm, or 2 mm to 4 mm.

[0166] The electrodes are electrically connected to the pulse generator, for example, by conductive wires. The electrodes may be electrically or communicatively connected to other units or portions of the pulse field ablation device, as well as to other units or portions of the device, such as a mapping device, an EP display device, a pacing device, an ECG recording device, a catheter signal interconnect circuit, an ECG trigger circuit, an electrical control circuit, a GUI unit, or a remote control unit. Aside from the ring-shaped electrodes described above, the electrodes may have any of many different shapes, such as a tube threaded around the filament, a coiled metal sheet, a square and / or rectangular shape, or other shapes of conductive material attached to the filament. Another possible form of the electrode (109) may be an elongated continuous electrode drawn along the surface of a portion of the filament (415) of the braided mesh (413) so as not to contact the filament (415) at their intersections, as shown in FIG. 8 . The electrode (109) may be attached to a particular filament (415) of the expandable basket by any means, such as mechanical attachment, swaging, crimping, adhesive bonding, lamination, deposition, and / or soldering. The electrodes can be made of any conductive material, such as copper, gold, steel, titanium, platinum, platinum-iridium, etc. If there is at least one filament made of a conductive material, it can also function as an electrode. If the entire conductive filament is not insulated, the entire filament may function as an electrode, or if the filament is, for example, partially electrically insulated, the bare, uninsulated portion may function as an electrode.

[0167] The conductive wires can provide electrical connection between the electrodes and the pulse generator. The conductive wires can be part of the structure of the basket assembly (401). For example, the conductive wires (417) can be at least partially disposed in the lumen (601) of the filament (415), as shown in FIG. 6C or FIG. 9. There can be one or more conductive wires (417) coupled to each of the electrodes, or one or more electrodes can be coupled to a single puller wire. The conductive wires (417) can be incorporated into one of the walls of the shaft assembly, for example, the wall of the outer elongate shaft. The conductive wires can also be disposed in a central lumen of the outer elongate shaft, or there can be a separate lumen in the outer elongate shaft suitable for conductor placement. The conductive wires can terminate adjacent to the electrodes or extend spatially further along the length of the filament beyond the electrodes. The conductive wires can be disposed, for example, along the entire length of the filament of the basket assembly. Optionally, some of the conductive wires (417) can terminate adjacent to the electrodes, while others can be directed spatially further along the filament beyond the electrodes, or can be positioned along the entire length of the filament of the basket assembly.

[0168] When the conductive wire is disposed along the entire length of the filament, an expandable basket design solution in which the filament is bent at the distal end of the expandable basket and returned to the expandable basket rather than severed is particularly advantageous. Because certain conductive wires are configured to carry electrical pulses between the electrode and the pulse generator, insulating the severed filament from the inner conductive wire can be extremely difficult in a terminal assembly. However, in examples with bent filaments with internal conductive wires, the insulation of the terminal assembly can be easily ensured.

[0169] The material used for the conductive wire can be any conductive material, such as copper, stainless steel, steel, nitinol, aluminum, gold, platinum, or silver. The conductive wire can be insulated or uninsulated. The wire can be insulated using any suitable material, such as polyimide, polyurethane, polyester, polyvinyl chloride (PVC), rubber, rubber-like polymers, nylon, polyethylene, polypropylene, silicone, fiberglass, or different fluoropolymers, such as ethylene propylene diene monomer (EPDM) or polytetrafluoroethylene (PTFE). The wire can be made with a single conductor or groups of conductors, but wires made with groups of conductors are sometimes called "cables." If the wire is insulated, the minimum breakdown voltage of the wire insulation should be at least 100 V, 500 V, 1000 V, 4000 V, or 10,000 V. The diameter of the wire with insulation can be limited by the dimensions of other structures in the device, such as the filament, and the minimum voltage it must be able to withstand without risk of failure. Typical diameters of the wire, with or without insulation, can be between 0.05 mm and 0.7 mm, or between 0.07 mm and 0.5 mm, or between 0.1 mm and 0.3 mm, or between 0.11 mm and 0.2 mm, or between 0.12 mm and 0.18 mm.

[0170] Constructing a braided mesh from an electrically insulating material, such as the one or more conductive wires within a hollow filament described above, may be particularly advantageous for ablation systems based on the principle of pulsed field ablation using pulsed electric fields. As will be further described, pulsed field ablation methods require an electric field generated around an electrode. To generate the field, an electrical pulse must be carried by a specific conductive wire between the electrode and a pulse generator. If the filament is non-conductive and the conductive wire is held inside the filament as described herein, electrical insulation of the specific conductive wire can be ensured even at voltage levels of several kV, e.g., 1 kV to 10 kV, carried by the conductive wire. However, the option of a braided mesh with at least one or more filaments made from a conductive material (e.g., nitinol, copper, stainless steel, steel, aluminum, gold, platinum, or silver) may also be possible. Such conductive filaments may be insulated, uninsulated, or only partially insulated. They may potentially conduct electrical current as well as act as electrodes (if uninsulated or only partially insulated) and / or as additional mechanical support for the braided mesh and, therefore, the expandable basket.

[0171] Another advantage of braided meshes made from polymer or thermoplastic elastomer filaments is their ease of manufacture compared to, for example, metal braided meshes. Braided meshes can be fabricated, for example, using a three-dimensional mandrel apparatus. The specific filaments forming the braided mesh can be arranged in a desired pattern on the mandrel. The filaments may already contain conductive wires. The entire structure can then be heated, for example, near the melting point of the filament material, and the structure can then be rapidly cooled. Because filaments made from thermoplastic elastomers or polymers generally require lower temperatures to reach their melting point than most metals, the manufacturing process can be faster, more efficient, and require less energy input. Another advantage of such a manufacturing process is that the conductive wires do not need to be heated to extreme temperatures, which could damage the wire's electrical properties. This situation can arise, for example, when the braided mesh is made from metal wires (metal filaments) and the braided mesh wires (filaments) also function as conductive wires.

[0172] The braided mesh with inserted conductive wires can be attached to the outer and inner elongate shafts to form an expandable basket and part of the basket assembly. Electrodes can be attached to specific filaments of the braided mesh before or after the braided mesh is attached to the elongate shafts. The pulse generator is the part responsible for generating the electrical signal for the catheter electrodes. The pulse generator can, for example, allow for setting the amplitude, shape, and / or number of electrical pulses during activation. The pulse generator can also diagnose the electrical waveform to measure power. The pulse generator can allow for synchronized operation with an ECG device or another part of the ablation system or device.

[0173] Additionally, methods of ablation using the described pulsed field ablation devices are disclosed.

[0174] One method includes positioning a catheter (105) adjacent to a treatment site, such as a heart chamber, in a patient via a blood vessel. The catheter (105) may be inserted percutaneously into the patient's blood vessel.

[0175] Other support structures and / or devices can be used to help navigate the distal tip of the catheter to its desired location. Examples of such devices include a guidewire or a sheath. The distal tip of the catheter can be delivered proximal to the treatment site in a collapsed state, for example, via a sheath. In the collapsed state, the diameter of the basket assembly at the distal tip of the catheter can be smaller than or approximately equal to the diameter of the outer elongate shaft of the catheter. Such a configuration allows for easy access of the distal tip of the catheter proximal to the treatment site.

[0176] The treatment site may be located, for example, within the body, for example, within or on the surface of the heart, for example, within a cardiac cavity, particularly, for example, within the left atrium of the heart. The treatment site may include, for example, the ostium of a pulmonary vein. Other locations of the treatment site may be, for example, any tubular tissue, organ, or blood vessel within the body, or, for example, the site of a tumor.

[0177] Once the catheter distal tip is delivered to the treatment site, the catheter's basket assembly unfolds from a collapsed or semi-collapsed configuration to one of its expanded configurations. This unfolding can be caused by the shape of the braided mesh or pretensioning of its filaments, by linear displacement of the inner elongate shaft relative to the outer elongate shaft along the catheter's central longitudinal axis, by tensioning of an additional support structure, such as an inner coil or balloon (not shown), or a combination thereof.

[0178] The catheter distal tip (107) may then be positioned adjacent to the target tissue at the treatment site (1001), such as at least a portion of the basket assembly (401), and / or a portion of the expandable basket (409) may be in contact with the treatment site (1001). In this position, at least a portion of the set of electrodes (109) disposed on the basket assembly (401) may be in contact with the tissue at the treatment site (1001). A schematic diagram of an exemplary position can be seen in FIG. 10. The contact assembly (411) can improve contact between the electrodes and the treatment site by having a flat design without distally protruding structures. When the basket assembly (401), particularly the basket assembly distal portion (405), does not have any distally protruding structures, it is easier to contact the electrodes with the treatment site, even when the treatment site is relatively flat.

[0179] After positioning the catheter distal tip adjacent to the treatment site, optional measurement steps can be performed with or without the catheter. Various types of measurements can be performed, for example, to diagnose the type or quality of tissue at or around the treatment site, the spatial location of the catheter distal tip, particularly relative to the treatment site, the contact of the catheter distal tip and / or specific electrodes with target tissue at the treatment site, or to understand electrophysiological processes in tissue adjacent to the electrodes. For example, electrodes can also be used to measure contact with target tissue and can be placed on the filaments of an expandable basket, e.g., a braided mesh. The measurement electrodes can be separate from the ablation electrodes, or the ablation electrodes can be used for measurements. Separate measurement electrodes can also be combined with the ablation electrodes, which have measurement capabilities, in a single catheter distal tip. To perform the measuring step, a separate measuring device can be used, such as a separate measuring catheter (not shown), an ECG device including an ECG trigger circuit, an ECG recording device, ECG electrodes, an intracardiac ECG (EGM), an intracardiac echo device, an esophageal temperature measuring device, a fluoroscopy device, an RTG device, an MR device, etc. The measuring step may be performed once or may be repeated several times during the ablation procedure.

[0180] Ablation of the target tissue at the treatment site (1001) uses the principle of pulsed field ablation, e.g., caused by a pulsed electric field of appropriate parameters. Although the terms "electric field" or "pulsed electric field" are referred to herein, the electric fields contemplated herein may further include a magnetic component.

[0181] The basket assembly deployment, measurement, and ablation procedures can be performed in several stages. For example, the expandable basket can be delivered adjacent to the treatment site in a fully collapsed configuration. After delivery, it can be deployed to a first expanded configuration. For example, a pretensioned shape of the braided mesh and / or filaments can trigger this first transition. In this configuration, for example, further manipulation with the basket assembly, as well as measurement and / or ablation, can be performed. Further repositioning, measurement, and / or ablation can also be performed in any order at this location.

[0182] The basket assembly can then be deployed to a second expanded configuration, which can be achieved, for example, by linear displacement of the inner elongate shaft relative to the outer elongate shaft along the central longitudinal axis of the catheter. In this configuration, for example, further manipulation of the basket assembly, as well as measurement and / or ablation, can be performed. Further repositioning, measurement, and / or ablation can also be performed in any order at this position.

[0183] The basket assembly can, for example, be deployed to several different expanded positions during which further repositioning, measurement, and / or ablation can be performed.

[0184] In the case of pulmonary vein isolation ablation, a set of electrodes can create a circular shape around the pulmonary vein ostium. After ablation, the shape of the ablated tissue may have a circular shape around the pulmonary vein ostium. By repositioning the basket assembly or by switching between different electrodes, several such shapes of ablated tissue can be created.

[0185] The pulsed electric field (PEF) can be generated, for example, by an electrical pulse, e.g., a high-frequency electrical pulse. The electrical pulse can be generated by a pulse generator and delivered to the target tissue by an electrode positioned at the distal tip of the catheter and in electrical contact with the pulse generator. The electrical pulse can be generated by a wide variety of electrical pulses, ranging from monophasic (single-polarity) pulses to symmetric and / or asymmetric biphasic pulses. Pulses may be combined with extra pre-pulses or extra measurement pulses for tissue conditioning. Pulses may be single pulses or repeated in trains, where pulse parameters may vary or remain constant. Trains of pulses can also be performed in sequences. The maximum amplitude of the pulses depends on the target tissue, electrode size, and / or electrode distance, and can generate an electric field with a maximum electric field strength of, for example, 0.1 kV to 10 kV, 0.4 kV to 5 kV, or 0.5 kV to 2 kV per centimeter of the target tissue volume. The pulse duration can be in the nanosecond to millisecond range, e.g., 2 ns to 10 ms, or 10 ns to 5 ms, or 10 μs to 1 ms. The pulse shape can be, for example, square, exponentially-like, rectangular, sawtooth, triangular, or sinusoidal.

[0186] Pulses can be monophasic or biphasic. Biphasic pulses can be symmetric or asymmetric. Pulses can be repeated from 1 to 100,000 times. The frequency of the high-frequency pulses can vary from 0.1 Hz to 10 Hz. The amplitude (Um) of monophasic pulses can vary from 100 V to 10 kV, and the peak-to-peak amplitude of biphasic pulses can vary from 200 V to 20 kV.

[0187] Figure 16 can serve as an example of a possible portion of a pulsed field ablation (PFA) protocol and as a clarification of terminology and expression related to PFA protocols. A PFA protocol includes a series of electrical pulses (1601) and pauses (1603, 1607, 1615). The electrical pulses (1601) can be further organized into units with specific hierarchies, such as trains (TR) and bursts (B).

[0188] Electrical pulses (1601) can be defined, for example, by their shape, amplitude (Um) at a particular voltage, and pulse length with duration (t1). The pulse amplitude (Um) can be either negative or positive in the case of monophasic pulses (pulses can have negative or positive voltages). Electrical pulses (1601) can be separated from one another by inter-pulse pauses (1603) defined by duration (t2) and voltage (Up). The voltage during the inter-pulse pauses (1603) can drop to 0 V or can have a positive or negative voltage value (Up). The absolute voltage value (Up) of the inter-pulse pause is less than the absolute voltage (amplitude (Um)) of the adjacent electrical pulse (1601), particularly up to 50% of the amplitude (Um) of the adjacent electrical pulse. In situations where the electrical pulses have a positive amplitude (Um), the voltage value (Up) of the inter-pulse pause (1603) remains positive between 0 V and the amplitude (Um) of the electrical pulse (1601), and in situations where the electrical pulse (1601) has a negative amplitude (Um), the voltage value (Up) of the inter-pulse pause (1603) remains negative between 0 V and the electrical pulse amplitude (Um). An example of an inter-pulse pause (1603) having a voltage different from 0 V is shown in Figure 17a. Biphasic pulses may be symmetric or asymmetric in at least one of time, amplitude, or energy.

[0189] An example of a biphasic electrical pulse is shown in Figure 17b. A biphasic pulse can have the same amplitude (voltage) of the positive phase (1701) and the negative phase (1703) with the same duration (t10, t12) of both phases (exemplary pulses A, D), or the amplitude and / or duration (t10) of the positive phase and the amplitude and / or duration (t12) of the negative phase can be different (exemplary pulses B, C). The resulting pulse can then have the same energy in the positive and negative phases of the pulse, or the energies of the positive and negative phases of the pulse can be different. A biphasic pulse with the same energy in both phases is sometimes called a symmetric biphasic pulse. A symmetric biphasic pulse can be balanced (if the duration and amplitude of both phases of the pulse are identical) or unbalanced (if the amplitude and / or duration are different for each phase). An asymmetric biphasic pulse has phases with different energies. Exemplary biphasic pulses A, B, and C have no pause between certain phases of the pulse (interphase pause), and exemplary pulse D is a biphasic pulse with an interphase pause (1705). The duration of the interphase pause of the pulse can be 0 μs to 50 μs, or 0 μs to 10 μs, or 0 μs to 5 μs.

[0190] A consecutive set or series of pulses, with or without inter-pulse pauses, may be referred to as a train (TR). Particular trains (TR) may be characterized, for example, by duration (t4) or number of pulses, and may be separated from one another by inter-train pauses (1607) having duration (t5), or inter-train pauses (1607) may separate trains with individual single pulses. A set or series of trains (TR) and inter-train pauses (1607) may be referred to as a burst (B), and may be characterized, for example, by duration (t6), number of trains (TR), number of pulses, or inter-burst pauses (1615) (having duration (t7) between particular bursts (B)).

[0191] As already mentioned above, the value of the voltage at the electrodes (Up) does not have to be reduced to 0 V between pulses, especially during the interpulse pause (1603), but can remain at a level such that the risk of generating bubbles due to electrolysis or temperature rise is nonexistent or very small, for example up to 50% of the amplitude (Um) of the adjacent electric pulse. This may also reduce unwanted relaxation of polar molecules, potentially shortening the length of at least some parts of the PFA protocol and therefore increasing the effectiveness of PEF therapy.

[0192] When pulses with amplitudes (Um) of hundreds to thousands of volts are applied, even if they are applied to the atria, there is a certain risk of depolarizing the ventricular muscle and causing undesired ventricular rhythms in the heart. Depolarization can be caused directly by an electric field or by secondary energy induction in another device, such as a catheter, placed in or near the atria or ventricles or both. Timing the active sequence (individual pulses, trains, and / or bursts) with a pause, as described below, has an effect called overdrive. The overdrive effect is commonly used in ablation catheterization procedures to reduce the risk of undesired cardiac rhythms by using an external pacemaker. An advantage of the proposed PFA protocol is that if the therapeutic (ablation) electrical pulse causes myocardial depolarization, it can also act as a pacing pulse to the heart, eliminating the need for an additional pacing device (e.g., an external pacemaker) to synchronize the pacing device pulse with the therapeutic pulse of the PFA protocol. This means that in this case, there is no need to use a pacing device to control the number of ventricular contractions per minute, detect individual ventricular contractions from the surface ECG, and then trigger ablation pulses accordingly.

[0193] The duration (t8) of one cycle (1609) of a burst (B), and the inter-burst pause (1615) between bursts, which can be between 201 ms and 800 ms, are determined by the range between the need to deliver pulses safely faster than the patient's actual heart rate (overdrive effect) and the need to maintain the heart rate at a safe level (roughly stated as 220 beats per minute minus age). The cycle duration can be fixed or variable within a prescribed range (201 ms to 800 ms) within the PFA protocol, for example, according to a sinusoidal or trigonometric function. Individual bursts (B) can have a duration (t6) of 1 ms to 200 ms, 30 ms to 180 ms, or 60 ms to 160 ms, which is a safe time for the applied burst of pulses (B) to contract the heart chambers and protect the ventricles from damage or undesirable rhythms. The burst (B) duration (t6) can also be fixed or variable in the described range (1 ms-200 ms) within the PFA protocol, for example according to a sinusoidal or trigonometric function.

[0194] This PFA protocol may have other positive effects on the ablation outcome, for example, reducing the risk of inducing undesired ventricular rhythms and / or maximizing the efficiency of PEF application.

[0195] However, although electroporation has been described as the main trigger of cardiomyocyte death after the application of PEF, actual cell death can instead be caused, for example, by electrical disruption of cardiomyocyte, mitochondrial, or nuclear membranes; by separating individual cells / cardiomyocytes (or cell groups) of the myocardium (e.g., by damaging intercalated discs or by mechanical damage due to a direct electric field, or hypercontraction); by damage to myofibers or myofibrils; by ATP depletion and insufficient production in cardiomyocytes due to hypercontraction; by loosening of intercellular junctions of cardiomyocytes; by myolysis of myocytes; by crumpling of cardiomyocytes directly under the influence of an electric field or by mechanical damage due to hypercontraction; by irreversible damage to the calcium cycle (whether due to non-physiological function of the sarcoplasmic reticulum, ion pumps, calcium channels, or calcium-binding proteins); by calcium overload of the myocardium - mitochondrial swelling (as a result of hypercontraction or damage of the cardiomyocyte sarcolemma or non-physiological function of calcium channels); or by the formation of reactive oxygen species (ROS) and subsequent oxidation of membrane phospholipids by PEF.

[0196] The electric field can be generated between one or more electrodes located at the distal tip of the catheter and a separate electrode, for example, located remotely on the patient's skin. The separate electrode may, in some embodiments, have a surface significantly larger than the combined surface area of ​​the active distal tip electrodes. This mode of operation is typically referred to as monopolar. Another option for generating the electric field is bipolar mode, in which the electric field is generated between two or more, usually closely spaced or adjacent, distal tip electrodes of different polarities. In this case, the combined surface area of ​​the active electrodes with one polarity is similar to the combined surface area of ​​the active electrodes with the second polarity.

[0197] In some embodiments, the electrodes (109) located on the distal assembly can operate in a hybrid mode between the previous two types. An example of such a configuration is shown in FIG. 11. In this mode, only the electrodes (109) located on the distal tip (107) are used for ablation. There is a first single electrode or group of electrodes operating in a mode with a first polarity (P1) and a second single electrode or group of electrodes operating in a mode with a different polarity (P2, which may be the opposite polarity) from the operating mode of the first electrode or group of electrodes. The surface or total surface of the first electrode or first group of electrodes is significantly smaller than the surface or total surface of the second electrode or group of electrodes. For example, there may be a third group of electrodes operating in a third mode in a high impedance (HI) state, where the impedance of the electrodes in the third group is higher, for example, than 500 Ω. The electrode operating in the third mode may be adjacent to an electrode or group of electrodes operating in the first mode.

[0198] One advantage of operating the electrode in this hybrid mode is that the generated electric field can have a more uniform current density compared to bipolar mode. Another advantage of the hybrid mode of operation is that the electric field generated in this mode can, in some embodiments, reach deeper into the target tissue compared to bipolar mode. For cardiac cavity ablation, the depth of the ablated target tissue (in one example, the target tissue can include myocardial tissue) can be up to 5 mm.

[0199] A variant of the hybrid operating mode of the electrode (109) with a group of electrodes (two or more electrodes) operating in a mode with a first polarity (P1) is shown in Figure 12. The functional principle of this operating mode is similar to the variant in which one electrode (109) operates in a mode with a first polarity (P1). For example, the total surface of the electrodes operating in a mode with a first polarity (P1) is significantly smaller than the total surface of the electrodes operating in a mode with a different polarity (P2).

[0200] An example of a group of electrodes (two or more electrodes) operating in a mode having a first polarity (P1) may be advantageous over an example of a single electrode operating in a mode having a first polarity (P1), for example, in situations where reducing the size of the electrode is advantageous. Reducing the size of the electrode may be advantageous or necessary when increasing the number of electrodes is necessary or desirable. For example, a larger number of electrodes is desirable when more precise mapping of the treatment site or more precise and / or more uniform ablation of target tissue at the treatment site is desired. Because the treatment site may be part of the human anatomy, the overall size of the pulsed field ablation device, particularly a catheter having a catheter distal tip, must be limited in accordance with the human anatomy. Therefore, if more electrodes are required for the ablation device, for a certain number of electrodes, the size of the electrodes must be limited so as to fit within the limited dimensions of the critical parts of the pulsed field ablation device, such as the catheter and / or its distal tip and / or its basket assembly. Another advantage of smaller electrode size is that such a configuration can help increase the depth of ablation.

[0201] Smaller electrode sizes can have other advantages, for example, in instances where the same electrode is used for ablation and for measurement, the same electrode must be configured to deliver the high-voltage pulse and record the measurement. For example, in measuring ECG signals, smaller electrodes may be advantageous.

[0202] However, there are also challenges associated with smaller electrodes. In examples involving pulsed field ablation, the electric field is generated between the electrodes, for example, by an electric pulse, e.g., a high-frequency electric pulse generated by a pulse generator. For effective ablation of the entire target region of the treatment site, it may be important to generate an electric field with a maximum electric field amplitude of several hundred volts to several kilovolts per centimeter of the target tissue volume. Using smaller electrodes means a smaller electrode surface area. When the electrode surface area is smaller, the voltage induced in the electrode must be higher to achieve the desired electric field density in the target tissue compared to a larger electrode with a larger surface area. Adverse effects of such a configuration may include a higher electric field density, a higher electric field strength, and / or possible sparking at the edge of the electrode. However, some or all of these issues can be addressed and overcome by using a group of selected electrodes (two or more electrodes) operating in a mode with a first polarity instead of a single electrode operating in a mode with a first polarity. With a first group of well-selected electrodes operating in a mode with a first polarity, a second group of electrodes operating in a mode with a different polarity, and a third group of electrodes operating in a third mode, possibly in a high-impedance state, the first group of electrodes and / or the second group of electrodes can function as virtual electrodes. That is, the electrodes in the first group can act together as one virtual electrode, and / or the electrodes in the second group can act as another virtual electrode. This configuration can reduce the strength and / or density of the electric field near the electrodes. Other positive effects of this configuration can be a reduced risk of sparking and increased ablation depth, or increased depth of ablated tissue at the treatment site.

[0203] The increase in the surface area of ​​the electrodes in the first group, and the resulting creation of virtual electrodes, can result in a reduction in the voltage that needs to be induced on the electrodes and / or the elimination of sparks primarily at the edges of the electrodes. However, the concept of disproportional surface areas of the electrodes in the first and second groups of electrodes can be preserved, meaning that the surface area or sum of the surface areas of the first electrode or first group of electrodes is significantly smaller than the surface area or sum of the surface areas of the second electrode or group of electrodes. The ratio of the surface area or sum of the surface areas of the electrodes in the first group to the sum of the surface areas of the electrodes in the second group of electrodes can be 2:3 to 1:100, or 3:5 to 1:80, or 3:5 to 1:70, or 1:2 to 1:50, or 1:2 to 1:40, or 1:2 to 1:30, or 1:2 to 1:20, or 1:3 to 1:15, or 1:3 to 1:10, or 1:4 to 1:8.

[0204] Adding an electrode to the first group of electrodes operating in a first polarity mode can significantly reduce the strength of the electric field near the electrode. For example, using four electrodes instead of one in the first group of electrodes operating in a first polarity mode reduces the electric field strength at the electrode surface by a factor of four, while in an example where three electrodes are used, the electric field strength is reduced by a factor of two. This reduction in strength may allow the use of lower voltages on the electrodes compared to solutions with only one electrode operating in a first polarity mode. Additionally or alternatively, the reduction can increase the depth of the ablated target tissue by increasing the area of ​​the electric field at a constant voltage per centimeter. The value of the voltage per centimeter of the area of ​​the electric field can be, for example, 50 V / cm to 3000 V / cm, or 100 V / cm to 1500 V / cm, or 250 V / cm to 1000 V / cm.

[0205] Certain electrodes at the distal tip of the catheter can be switched to one or more modes during ablation. They can be switched during a single ablation cycle or several ablation cycles. Electrodes may be switched to one or more modes several times during a single ablation cycle or several ablation cycles. In some embodiments, it is even possible to have two or more groups of electrodes simultaneously operating in a mode with a first polarity and other groups of electrodes operating with different polarities, with or without electrodes operating in a high impedance state.

[0206] A particular electrode can be switched into one of the modes, for example, before or after each pulse, before or after several consecutive pulses within a pulse train, before or after one or several pulse trains within a pulse train, or, for example, before or after one or several bursts of pulses.

[0207] The layout or spatial pattern of the electrodes at the distal tip can be created to allow for hybrid electrode operation modes and / or for the purpose of creating virtual electrodes. Because the electrodes can be switched between one or more modes during ablation, the resulting virtual electrodes can have different spatial shapes, meaning that the electric fields generated around and between the virtual electrodes can have different shapes with different magnetic field configurations and / or electric field densities and strengths. Examples of spatial patterns of electrodes at the distal tip, specifically the expandable basket, can be seen in Figures 13A and 13B. Figure 13A shows a front view of a basket assembly (401) with a spatial pattern of electrodes (109) suitable for creating virtual electrodes by switching the electrodes (109) between different operation modes with a first polarity and a different polarity and / or high impedance.

[0208] Figure 13B again shows a front view of the basket assembly (401) with a spatial pattern of electrodes suitable for creating virtual electrodes by switching the electrodes (109) to different modes, but this time the electrodes are positioned in areas where the filaments (415) cross each other (filament crossing points).

[0209] An example of a possible layout of electrodes already switched into a hybrid operating mode can be seen in Figure 14, which is also a front view of the basket assembly (401). A first group of electrodes (109) are operating in a mode having a first polarity (P1) and together form a first virtual electrode (1401). Another group of electrodes (109) are operating in a mode having a different polarity (P2) and together create a second virtual electrode (1403). In this configuration, when an electrical pulse is delivered from the pulse generator (103) to the electrodes (109), an electric field is generated between and around the virtual electrodes (1401, 1403). Some of the electrodes (109) may be operating in a third mode, e.g., in a high impedance (HI) state.

[0210] Electrodes in a high-impedance state (higher than 500 Ω) can help shape the electric field generated between and around electrodes from the first group of electrodes and the second group of electrodes, and / or between or around virtual electrodes. In one example, assigning a high-impedance state to electrodes spatially adjacent to electrodes operating in a mode with a first polarity can have a positive effect on the shape of the electric field, such that a portion of the electric field capable of causing ablation reaches deeper into the target tissue at the treatment site, compared to an operating mode without electrodes in a high-impedance state. This phenomenon can have a positive effect on the quality and uniformity of the ablation procedure. Electrodes in a high-impedance state can be spatially positioned between the first group of electrodes and the second group of electrodes.

[0211] An exemplary pattern of electrodes (109) is shown in more detail in FIG. 15A. The electrodes (109) create a repeating cross, square, or rectangular pattern on the filaments (415) of the braided mesh in one of the expandable basket's expanded configurations. From this view, perpendicular to the tangent plane (e.g., contacting the expandable basket at the intersections (1501) of four adjacent electrodes), the pattern appears two-dimensional, but is actually three-dimensional because the electrodes (109) are fixed to or are part of the filaments (415) of the braided mesh, forming the expandable basket, and therefore the pattern conforms to the curvature of the expandable basket. This pattern of electrodes is advantageous in embodiments using a group of electrodes operating in a mode having a first polarity (P1). In this example, the group of four adjacent electrodes operating in a mode having a first polarity (P1), thus creating the first virtual electrode (1401), has either a cross shape as shown in FIG. 15A, or a square or rectangle as shown in FIG. 15B. The advantage is that both virtual electrodes (1401) generated by both shapes can be combined with a second virtual electrode, possibly prompted by an electrode in a high impedance state, to generate an electric field with specific qualities (potential shape, magnitude, density, gradient) suitable for ablation of the target tissue.

[0212] 15C shows an example of an electrode pattern in which electrodes (109) are placed at the regions where filaments (415) cross each other (filament intersections). Also shown here is a group of exemplary electrodes operating in a mode having a first polarity (P1).

[0213] The exact shape of the electrode pattern depends in part on the shape of the expandable basket. This also means that the pattern and shape of the group of electrodes forming the virtual electrodes may differ in the collapsed configuration and / or different expanded configurations of the expandable basket. In most expanded configurations of the expandable basket, the rectangles and squares formed by the electrodes as described above are tilted, forming shapes that more closely resemble diamonds or rhomboids. The same applies to the angle between the two imaginary lines forming the cross and passing through the electrodes, which is not a right angle in most expanded configurations.

[0214] Figure 34 shows an exemplary pattern layout of electrodes (109) included in an expandable basket imprinted on a flat, two-dimensional plane. The electrodes are arranged in a pattern such that in all expanded configurations of the expandable basket, the distance (3401) between the closest points of longitudinally adjacent electrodes (109) in the direction of + / - 45° from the central axis (203) (measured perpendicular to the axis of the central axis (203)) is less than 2 mm. An example of such a pair of longitudinally adjacent electrodes (109) in the direction of + / - 45° from the central axis (203) can be seen in Figure 34.

[0215] When using high-voltage pulses in the human body, it may be necessary for safety reasons to synchronize pulse delivery with the cardiac cycle, for example to avoid ventricular rhythm. Pulse field ablation devices may incorporate or use means for such synchronization, including triggering pulse delivery by this synchronization means. The synchronization means may be, for example, an ECG device.

Claims

[Claim 1] 1. An ablation device for pulsed field ablation of tissue, comprising: An ablation device comprising at least one of a pulse generator and a catheter.

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