electrosurgical generator

Abstract

The present invention discloses an RF electrosurgical system featuring an RF electrosurgical generator with a user interface and an output for delivering RF energy to an RF ablation instrument. The RF electrosurgical generator is equipped with software designed to measure impedance values ​​while delivering voltage pulses to the ablation instrument. If the measured impedance value exceeds a predetermined impedance threshold, the software is programmed to either partially or fully reduce the voltage amplitude of each voltage pulse. This innovative system ensures optimal performance and safety during electrosurgical procedures by dynamically adapting the voltage output based on real-time impedance measurements.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Application No. 63 / 488,950, entitled "Generator for Electrosurgical Use," filed March 7, 2023, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] Electrosurgery is a procedure in which high-frequency alternating polarity electrical current (radio frequency or RF current) is applied to living tissue to ablate, coagulate, desiccate, or electrocauterize the tissue. Its benefits include the ability to make precise incisions with limited blood loss.

[0003] RF current or energy, typically alternating between about 100 kilohertz and about 4 megahertz, induces ionic vibrations that generate intracellular heat. Depending on certain characteristics of the current, different levels of intracellular heat can be rapidly generated, resulting in different tissue outcomes, specifically ablation, coagulation, desiccation, and electrocautery. Electrosurgical devices are typically classified as wet-field and dry-field. Wet-field devices operate in saline solution or body fluids as a result of the alternating current passing between two electrodes or between a single electrode and a ground return pad.

[0004] Most wet-field electrosurgical systems typically have at least an ablation mode and a coagulation mode. In ablation mode, a small area of ​​tissue is rapidly heated, creating a vapor pocket that bursts through vaporization, allowing for the incision of small sections of soft tissue. While the peak voltage can be very high, the average power required to ablate tissue is relatively low. In coagulation mode, the average voltage output is typically higher than that in ablation mode, generating a greater thermal effect, leaving the tissue largely intact but destroying cells at the point of contact, disrupting and sealing small blood vessels, and staunching bleeding from capillaries and arterioles. Cautery mode is typically used in dry-field electrosurgical procedures, generating an electrical arc between the air gap and the tissue, creating a more superficial "cauterization" of the tissue. However, arcing, intentional or unintentional, is also possible during wet-field electrosurgical procedures.

[0005] RF electrosurgery is typically performed using an RF electrosurgical generator and a surgical instrument containing either one electrode (monopolar instruments) or two electrodes (bipolar instruments). Some RF electrosurgical generators can be used with either monopolar or bipolar instruments.

[0006] Monopolar instruments typically have a single electrode or conductive surface connected to an RF electrosurgical generator, with a second electrode (often in the form of a pad or external adhesive electrode) placed in contact with the patient's skin to complete the RF electrosurgical generator's circuit. Bipolar instruments often contain two electrodes connected to different circuit paths that, when placed near or in contact with tissue, complete the RF electrosurgical generator's electrical circuit. In wet-field procedures, monopolar instruments are often more successful at vaporizing or ablating tissue than bipolar instruments. Summary of the Invention

[0007] In some aspects, the technology described herein relates to an RF electrosurgical system, including: an RF electrosurgical generator including a user interface and one or more outputs that supply RF energy to an RF ablation instrument connected to the generator; the RF electrosurgical generator executing software configured to: measure measured impedance values ​​while providing a plurality of voltage pulses to the ablation instrument; and partially or completely reduce the voltage amplitude of each of the plurality of voltage pulses when the measured impedance value exceeds an impedance threshold.

[0008] In some aspects, the technology described herein relates to RF electrosurgical systems having an impedance threshold in the inclusive range of about 500 ohms to about 2,000 ohms.

[0009] In some aspects, the technology described herein relates to RF electrosurgical systems in which the impedance threshold is a predetermined threshold or percentage impedance increase.

[0010] In some aspects, the technology described herein relates to an RF electrosurgical system in which impedance thresholds are looked up in a database stored in the memory of the RF electrosurgical generator based on the cutting instrument model number, serial number, or identification.

[0011] In some aspects, the technology described herein relates to an RF electrosurgical system in which the software is further configured to partially or completely reduce the voltage amplitude of each of the plurality of voltage pulses when a predetermined voltage amplitude threshold for one of the plurality of pulses is exceeded and / or a predetermined pulse time threshold for one of the plurality of pulses is exceeded.

[0012] In some aspects, the technology described herein relates to RF electrosurgical systems in which the time intervals between multiple pulses are non-uniform.

[0013] In some aspects, the technology described herein relates to RF electrosurgical systems in which multiple voltage pulses are arranged in bursts separated by relaxation periods.

[0014] In some aspects, the technology described herein relates to RF electrosurgical systems in which RF energy alternates within the inclusive range of about 4 and 5 megahertz.

[0015] In some aspects, the technology described herein relates to RF electrosurgical systems in which RF energy is alternating at 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0 megahertz.

[0016] In some aspects, the technology described herein relates to RF electrosurgical systems in which RF energy is generated at a duty cycle of about 1% to about 20%.

[0017] In some aspects, the technology described herein relates to an RF electrosurgical system in which the RF electrosurgical generator prevents generation of multiple voltage pulses during one or more of atrial diastole, atrial systole, ventricular diastole, and / or ventricular systole.

[0018] In some aspects, the technology described herein relates to RF electrosurgical systems in which software is configured to monitor electrocardiogram (ECG) data and limit RF energy to only a portion of a patient's cardiac cycle, rather than all of it.

[0019] In some aspects, the technology described herein relates to an RF electrosurgical system in which software displays a user interface configured to select which portion of a patient's cardiac cycle receives RF energy.

[0020] In some aspects, the technology described herein relates to an RF electrosurgical system in which the ablation instrument is a leaflet treatment device removal system.

[0021] In some aspects, the technology described herein relates to RF electrosurgical systems in which the cutting instrument is a loop containing one or more electrodes.

[0022] In some aspects, the technology described herein relates to an RF electrosurgical system in which the cutting instrument is a resecting loop catheter containing multiple electrodes, each with a separate electrical pathway in communication with an RF electrosurgical generator.

[0023] In some aspects, the technology described herein relates to an RF electrosurgical system in which software is configured to monitor measured temperature values ​​from an ablation instrument and prevent RF energy when the measured temperature values ​​exceed a predetermined temperature threshold.

[0024] In some aspects, the technology described herein relates to RF electrosurgical systems in which the ablation instrument is an RF guidewire having a distal portion that forms a coiled shape in an unconstrained state.

[0025] In some aspects, the technology described herein relates to an RF electrosurgical system in which software is configured to measure impedance from an ablation instrument, compare it to a tissue contact impedance threshold, and alert the user to tissue contact when the tissue contact impedance threshold is exceeded.

[0026] In some aspects, the technology described herein relates to an RF electrosurgical system in which software is configured to measure impedance from an ablation instrument, compare it to a device contact impedance threshold, and alert the user to tissue contact when the device contact impedance threshold is exceeded.

[0027] In some aspects, the technology described herein relates to an RF electrosurgical system in which software is configured to measure the duration of use of a cutting instrument.

[0028] In some aspects, the technology described herein relates to a method of operating an RF electrosurgical system, comprising: executing software on an RF electrosurgical generator including a user interface and one or more outputs that supply RF energy to an RF ablation instrument connected to the generator; measuring a measured impedance value on the RF electrosurgical generator while providing a plurality of voltage pulses to the ablation instrument; and partially or completely reducing the voltage amplitude of each of the plurality of voltage pulses on the RF electrosurgical generator when the measured impedance value exceeds an impedance threshold.

[0029] In some aspects, the technology described herein relates to an RF electrosurgical system, including: an RF electrosurgical generator including a user interface and one or more outputs that deliver RF energy to an RF ablation instrument connected to the generator; the RF electrosurgical generator executing software configured to: prevent RF energy from being delivered to the ablation instrument during one or more of atrial diastole, atrial systole, ventricular diastole, and / or ventricular systole. [Brief explanation of the drawings]

[0030] The following drawings are included to illustrate certain exemplary aspects of the present disclosure and should not be construed as exclusive or limiting. The subject matter of the present disclosure may include considerable modifications, variations, combinations, and equivalents in form and function that would be readily apparent to one skilled in the art having the teachings of the present disclosure. The present disclosure refers to the drawings as follows:

[0031] [Figure 1] FIG. 1 shows a perspective view of an RF electrosurgical system 100 including an RF electrosurgical generator 102 configured to supply RF energy to one or more surgical instruments, according to some embodiments.

[0032] [Figure 2] FIG. 2 is a graph of voltage amplitude versus time illustrating an exemplary voltage train burst 130 and relaxation period 132, according to some embodiments.

[0033] [Figure 3] FIG. 3 is a graph of voltage amplitude versus time illustrating exemplary voltage pulses 134 within each voltage train burst 130, according to some examples.

[0034] [Figure 4] FIG. 4 illustrates a graph of voltage amplitude and impedance of RF energy output, according to some embodiments.

[0035] [Figure 5] FIG. 5 shows, by way of example, an ECG graph of voltage versus time demonstrating a patient's cardiac cycle, according to some embodiments.

[0036] [Figure 6] FIG. 6 illustrates a side view of an example leaflet treatment device removal system 150 that may be used to remove a leaflet clip or similar device from a patient's heart, according to some embodiments.

[0037] [Figure 7] FIG. 7 shows a diagram of a resecting loop 160 including only a single electrode 162 and adjacent insulating portion 164 located at the distal end of the resecting loop 160, according to some embodiments.

[0038] [Figure 8] FIG. 8 shows a diagram of a resection loop 166 having multiple electrodes 162A, 162B, 162C, according to some embodiments.

[0039] [Figure 9] FIG. 9 shows a diagram of a resection loop 166 having multiple electrodes 162A, 162B, 162C, according to some embodiments.

[0040] [Figure 10]FIG. 10 illustrates a capture basket catheter 152, a snare catheter 154, and a distal portion of a resecting loop catheter 156 positioned on the underside or ventricular side of a leaflet clip 40 connected to a heart valve leaflet 20, according to some embodiments.

[0041] [Figure 11] FIG. 11 shows a snare catheter 154 that may be positioned and tightened around a leaflet clip 40 to pull the leaflet clip 40 toward or into the basket of a capture basket catheter 152, according to some embodiments.

[0042] [Figure 12] FIG. 12 shows an example of a resecting loop device 170 having a hook, "C" shape, or open loop shape 172, according to some embodiments.

[0043] [Figure 13] FIG. 13 shows a capturing member 180, which may be an elongated wire, multiple wires, a tubular structure, or similar elongated structure, that may be positioned within a lumen of a catheter body 182, according to some embodiments.

[0044] [Figure 14] FIG. 14 shows, by way of example, a capturing member 180 that may be an elongated wire, multiple wires, a tubular structure, or a similar elongated structure and may be positioned within a lumen of a catheter body 182, according to some embodiments.

[0045] [Figure 15] FIG. 15 illustrates another example of an RF guidewire 190 that may be advanced from a catheter or sheath 192, according to some embodiments.

[0046] [Figure 16] FIG. 16 illustrates another example of an RF guidewire 190 that may be advanced from a catheter or sheath 192, according to some embodiments.

[0047] [Figure 17] FIG. 17 illustrates a contact interface 200 that may be displayed on the display 104 of the RF electrosurgical generator 102, according to some embodiments.

[0048] [Figure 18] FIG. 18 illustrates an electrode activation interface 202 that allows a user to determine which electrodes become electrically active when RF power is supplied to an ablation instrument (eg, a resection loop), according to some embodiments. Detailed Description

[0049] It will be appreciated by those skilled in the art that the present disclosure is not limited to what has been particularly shown and described herein. Various modifications and variations are possible in light of the teachings herein without departing from the scope, spirit, or intent thereof.

[0050] Although different examples may be described in this specification, it is specifically contemplated that any of the features from the different examples may be used and combined in any combination. In other words, features of the different examples may be mixed and matched with one another. Thus, even if every permutation of features from the different examples is not explicitly shown or described, it is the intent of the present disclosure to encompass such combinations as would be understood by one of ordinary skill in the art.

[0051] The terms used in this disclosure should be interpreted in an permissive manner and are not intended to be limiting. In the drawings, like numbers refer to like elements. Unless otherwise noted, all accompanying drawings are not to scale. Unless otherwise noted, the term "about" is defined to mean plus or minus 5% of the stated value.

[0052] The terms "distal" or "distally" generally refer to the direction or region toward the end of the device within the patient's body (e.g., away from the physician / clinician), and the terms "proximal" or "proximally" refer to the direction or region toward the end of the device that remains outside the patient's body (e.g., toward or closer to the physician / clinician or the handle / hub of the device).

[0053] This specification generally relates to various aspects of an improved RF electrosurgical system including an RF electrosurgical generator. The improved RF electrosurgical system may be used in a variety of different procedures, but may be particularly useful in procedures performed within or involving a patient's heart.

[0054] In a first example, an RF electrosurgical system includes an RF electrosurgical generator that supplies RF current to one or more electrosurgical instruments. In some examples, the RF electrosurgical generator may be configured to generate cavitational "sparks" that achieve effective and reproducible wet-field ablation while minimizing heat generation within the tissue. A cavitational spark is generally defined as the creation of a spark or plasma within the wet-field environment between the active electrode and the patient's tissue, which rapidly heats and pre-explodes tissue cells. When applied correctly, this cavitational spark may produce the desired ablation while limiting excessive heat to adjacent or nearby tissue. Furthermore, such cavitational sparks may better enable the desired ablation when the active electrode is fully immersed in the tissue, fully immersed in the bloodstream, or in partial contact with the tissue and blood.

[0055] RF electrosurgical generators create such cavitation sparks with improved ablation performance by providing multiple pulses (e.g., pulse trains or bursts). Each pulse is varied to provide a rapid voltage increase resulting in a high voltage peak, while controlling this voltage based on measured impedance. At certain voltages, the current of these voltage peaks may overcome the electrode-tissue interface and produce cavitation sparks that locally disrupt tissue and produce the desired ablation effect.

[0056] When a cavitation spark occurs, the impedance increases. Therefore, the impedance may be continuously measured (or at least during voltage application), and if it exceeds a predetermined threshold, a cavitation spark is presumed to have been generated. The voltage amplitude may be immediately reduced to minimize excessive heat generation. While the timing of the impedance increase appears relatively simultaneous with the cavitation spark caused by the high voltage, the impedance may have a very small time offset (e.g., a few microseconds). However, for the purpose of generating one or more cavitation sparks for ablation purposes, such a small time offset may not significantly affect ablation performance.

[0057] This pulsing process may be repeated, for example, after a short relaxation period. These groups or bursts of pulses may be duty cycled to produce a significantly lower time-averaged output power than would be the case for a continuous signal (e.g., between 1% and 50%, or more specifically, a 10% duty cycle).

[0058] The details of these pulses are explained later in this specification.

[0059] In another example, the RF electrosurgical generator may limit RF ablation energy to only specific portions of the patient's cardiac cycle. For example, ablation may be generally limited to diastole or systole, or to one or more of atrial diastole, atrial systole, ventricular diastole, and / or ventricular systole. RF ablation energy may be limited to any combination of these cardiac cycle phases (e.g., one, two, or three cardiac cycle phases, as well as all cardiac cycle phases). In a similar example, ablation may be limited to one or more portions of an ECG measurement, such as one or more of the P wave, PR segment, Q wave, R wave, S wave, ST segment, PR interval, QRS complex, or QT interval. Similarly, RF ablation energy may be limited to any combination of these ECG portions. This may be particularly useful for procedures involving ablation within the heart or in areas near or adjacent to the heart.

[0060] By restricting RF energy to only a portion of a patient's cardiac cycle, many different procedures can be performed. For example, cardiac valve cusps, such as the mitral, aortic, tricuspid, or pulmonary valve, may be ablated only during a specific portion of a patient's cardiac cycle. In another example, cardiac valve treatments, such as cardiac valve cusp clips, may be ablated only during a specific portion of a patient's cardiac cycle. In another example, RF energy may be restricted when creating openings through the atrial or ventricular septum of a patient's heart.

[0061] The RF generator may limit RF energy to the active electrodes by monitoring the patient's heart. This monitoring may include monitoring the patient's ECG readings. The RF generator may be configured to connect directly to ECG leads to measure and record ECG data, or the RF generator may connect to a separate ECG machine and receive ECG data from the ECG machine in real time during the procedure. The RF generator may include software stored in a non-passive memory and executed by a processor that analyzes the ECG data to determine the patient's cardiac cycle phase, compares the patient's cardiac cycle phase to predetermined timing settings for RF energy (i.e., at which portion of the cardiac cycle the RF energy should be applied in the ECG readings), and then delivers RF energy only at times in the cardiac cycle specified by the predetermined timing settings for RF energy.

[0062] In some examples, the ablation instrument may include identification data such as a serial number, device model number, and / or similar identification. The identification data may be stored in a readable memory (e.g., flash memory) within the ablation instrument and accessed by the RF electrosurgical generator when connected to the ablation instrument, or may be accessed via wireless communication technology such as RFID or Wi-Fi. Additionally, software in the RF electrosurgical generator may track the duration of use of the ablation instrument, sense contact with tissue or an implanted device, or control which electrodes RF energy may be transmitted to.

[0063] 1 shows a perspective view of an RF electrosurgical system 100 including an RF electrosurgical generator 102 configured to supply RF energy to one or more surgical instruments. As described in more detail below, the RF electrosurgical generator 102 includes several aspects that may improve tissue ablation and / or perforation, particularly in wet field environments (e.g., environments containing bodily fluids such as blood, saline, or other fluids).

[0064] The RF electrosurgical generator 102 may take a variety of different forms, but generally may include an outer housing that supports a display 104 and one or more outputs 106 configured to electrically connect to one or more surgical instruments, other devices (e.g., ECG measurement devices), or other interface devices (keyboard, mouse, etc.).

[0065] In this example, the display 104 may be a touchscreen that allows user input to adjust or operate the software executed by the RF electrosurgical generator 102. Additionally or alternatively, other input interfaces may be included, such as physical buttons or a separately connected keyboard / mouse.

[0066] The RF electrosurgical generator 102 may be configured to connect to monopolar and / or bipolar surgical instruments. Typically, monopolar instruments include one “active” electrode that is placed inside the patient to ablate tissue and another electrode that externally contacts the patient's skin. For a monopolar example, FIG. 1 shows a pad electrode 108 that may be placed against the patient's skin and a monopolar catheter 110 that is placed inside the patient. Both the pad electrode 108 and the monopolar catheter 110 are connected to one or more outputs 106 of the RF electrosurgical generator 102, so that when an electrode on the monopolar catheter 110 contacts tissue inside the patient, a circuit is completed and RF energy is applied at the location of the tissue contact. For a bipolar example, FIG. 1 also shows a bipolar catheter 112 that includes two electrodes near its distal end, both with separate electrical paths back to the RF electrosurgical generator 102. When the two electrodes of the bipolar catheter 112 contact tissue, they complete a circuit with the RF electrosurgical generator 102, thereby delivering RF energy to the contacted tissue.

[0067] The RF electrosurgical generator 102 may further include a processor configured to execute software code and non-volatile memory configured to store software, data, and similar files. The processor may execute software stored in the non-transitory memory and display interfaces on the display 104, as well as accept user input (e.g., from a touchscreen aspect of the display 104) and accept data from connected instruments, sensors, and / or devices (e.g., an ECG machine).

[0068] The processor and software may further include a power source including circuitry configured to supply RF energy to one or more surgical instruments (e.g., pad electrodes 108, monopolar catheter 110, and bipolar catheter 112) through one or more of the one or more outputs 106.

[0069] For purposes of this specification, RF energy (also referred to as RF current) refers to alternating current within a range of about 100 kilohertz to about 5.5 megahertz. In some examples, the RF electrosurgical generator 102 may generate the aforementioned cavitation sparks with RF energy within a range of about 4 megahertz to about 5 megahertz. In a further example, the RF electrosurgical generator 102 may generate the aforementioned cavitation sparks with RF energy of about 450 kilohertz.

[0070] The RF electrosurgical generator 102 may apply RF energy such that one or more surgical instruments create cavitation sparks between the active electrode and tissue in a wet field environment. As described in detail below, the RF electrosurgical generator 102 may apply RF energy in a manner that limits excess heat to adjacent nearby tissue and improves ablation function even when completely surrounded by tissue, completely surrounded by blood, or partially in contact with tissue and blood.

[0071] To more clearly define the description of RF energy output from RF electrosurgical generator 102 described below, some mathematical equations are provided below.

[0072] The output voltage of the RF electrosurgical generator 102 may be generally described by the following equation:

[0073] v(t)=Av(t)cos(ωt)

[0074] Av(t) represents the amplitude of the voltage fluctuation over time.

[0075] ω is the radian frequency of the RF energy output, which can also be expressed as ω = 2πf, where f is the frequency in hertz of the output (e.g., but not limited to, in the range of about 400-500 kilohertz, or about 450 kilohertz).

[0076] The output current can be measured through a suitable resistor R in series with the output circuit and by measuring the voltage drop across the resistor R divided by its resistance. This can be expressed as:

[0077] i(t)=Ai(t)cos(ωt)

[0078] Ai(t) represents the amplitude of the current fluctuation over time (vr(t) / R).

[0079] ω is the radian frequency of the RF energy output as noted in the previous equation.

[0080] Since resistor R can be of a purely resistive (non-reactive) type, the phase angle between the current and voltage will be zero, so the phase of the current may be considered the same as the phase of the voltage. θ is the phase angle between the output voltage and the output current.

[0081] The load impedance can be calculated from the measured output voltage and current and may be described by the following formula:

[0082] Z(t) = v(t) / i(t) = |Za(t)| cos(ωt + θ); where θ is the phase angle between the applied voltage v(t) and the resulting current i(t), which depends on the reactive components of the generator load formed by the interconnecting cables, electrodes, electrode-tissue interface, tissue, ground return pad, and return cables.

[0083] where |Za(t)| = |Av(t) / Ai(t)|

[0084] As previously described, the RF electrosurgical generator 102 produces an RF energy output that may provide improved ablation between the active electrode and the patient's tissue. This improved ablation may be achieved by providing multiple pulses (e.g., pulse trains or bursts), each pulse varied to provide a rapid voltage increase that results in a voltage peak, while controlling or limiting this voltage based on measured impedance. At certain voltages, the current of these voltage peaks may create cavitation sparks across the electrode-tissue interface that locally disrupt tissue and produce the desired ablation effect.

[0085] FIG. 2 is a graph of voltage amplitude versus time illustrating exemplary voltage train bursts 130 and relaxation periods 132, and FIG. 3 is a graph of voltage amplitude versus time illustrating exemplary voltage pulses 134 within each voltage train burst 130.

[0086] The RF electrosurgical generator 102 may be configured to provide RF energy including multiple voltage train bursts 130 with relaxation periods 132 between each voltage train burst 130. Generally, the voltage train bursts 130, voltage pulses 134, and relaxation periods 132 are arranged to provide a significantly lower time-averaged output power than would be the case if the voltage train bursts 130 were a continuous signal without relaxation periods 132 or voltage pulses 134. For example, the RF electrosurgical generator 102 may be configured to provide this RF energy output with a duty cycle within the following inclusive ranges: about 0.1% to 50%, about 0.1% to 30%, about 0.1% to about 20%, or about 0.1% to about 10%. In some specific examples, the duty cycle may be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 percent.

[0087] The duty cycle may be calculated or estimated in several ways. In one example, the duty cycle may be the ratio of the duration of a burst 130 to the total period of the repeating burst 130. In this case, within each burst there is a time-varying amplitude such that the total burst energy is less than the peak burst value multiplied by the burst duration. Additionally, as explained further below, each burst may have different energy due to different voltage pulses. Therefore, it may be useful to integrate the power delivered for a particular burst waveform.

[0088] The RF electrosurgical generator 102 may be configured to provide RF energy having an alternating frequency within the inclusive range of about 100 kilohertz to about 5.5 megahertz. In some examples, the RF energy may have a frequency within the inclusive range of about 4 megahertz to about 5 megahertz. Some specific examples include 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0 megahertz, and frequencies therebetween. Other specific examples may include 4.41, 4.42, 4.43, 4.44, 4.45, 4.46, 4.47, 4.48, 4.49, 4.50, 4.51, 4.52, 4.53, 4.54, 4.55, 4.56, 4.57, 4.58, 4.59, 4.60 megahertz, and frequencies therebetween. Generally, 100 kilohertz tends to be the lower limit for this purpose to avoid the possibility of the generator current stimulating nerves. Frequencies above 5 megahertz may offer advantages in certain cases, but generally in the 4 to 5 megahertz range, the reactance due to the interconnecting cables (both the electrode cable and the ground return pad cable) tends to be small, so that the load impedance appears relatively close to its effective value (small reactance).

[0089] The relaxation periods 132 between voltage train bursts 130 may be the same or uniform in time between voltage train bursts 130, or may vary in time. While either option may help achieve a desired duty cycle of the overall RF energy output, varying the time between voltage train bursts 130 based on the voltage characteristics (which may vary in amplitude and time) of each voltage pulse 134 of the voltage train burst 130 may be useful in achieving a desired duty cycle and / or maintaining a desired temperature of the active electrode or nearby tissue. Thus, in one example, the RF electrosurgical generator 102 may monitor the voltage amplitude of multiple voltage pulses 134 of a voltage train burst 130, determine an average voltage of the voltage train burst 130, compare the average voltage to a predetermined limit based on duty cycle or temperature values ​​on or near the active electrode, and then increase or decrease the relaxation periods 132 to achieve the desired duty cycle or temperature reading. In other examples, energy (power multiplied by time) or peak voltage may be used instead of average voltage.

[0090] In some examples, the relaxation period 132 may be used to characterize the ECG signal to optimize the timing of the voltage train burst 130 with the portion of the cardiac cycle, as described elsewhere herein. In some examples, the relaxation period 132 may be tailored to a desired ablation rate or tactile sensation during ablation; for example, a shorter relaxation period 132 may promote faster ablation, while a longer relaxation period 132 will result in a slower ablation rate and generate less heat. In that regard, the RF electrosurgical generator 102 may include a user interface that allows a user to increase or decrease the relaxation period 132. In some examples, the relaxation period 132 may be dynamically decreased following a relatively high amplitude voltage train burst 130 to help reduce or manage heat transfer and / or to provide sufficient time for internal capacitors in the generator power supply to recharge and prepare for the next voltage train burst 130.

[0091] 3, each of the voltage train bursts 130 includes a plurality of voltage pulses 134 (shown as shaded regions). The number of voltage pulses 134 may be a predetermined number or may be a variable number that depends on other calculations or measurements, such as the duty cycle.

[0092] At the initiation of the voltage pulse 134, the voltage amplitude increases rapidly over time. The voltage amplitude of the voltage pulse 134 may be partially or completely reduced (e.g., to zero voltage amplitude) based on a measured impedance value 138 of the RF energy, as seen in FIG. 4. FIG. 4 shows a graph of voltage amplitude and a graph of impedance of the RF energy output. Specifically, the RF electrosurgical generator 102 may have an impedance threshold 140 at which cavitation sparks will or may occur in a wet field environment. The impedance threshold 140 may be a predetermined threshold, such as within the inclusive range of about 500 ohms to about 2,000 ohms. In some examples, the impedance threshold 140 may also be user-adjustable. In some examples, the impedance threshold 140 may be dynamically calculated based on a percentage increase in the measured impedance value 138 or other algorithm (e.g., within the range of about 200% to about 10,000%).

[0093] In some examples, the impedance threshold 140 may be calibrated by the manufacturer based on the ablation instrument. The software of the RF electrosurgical generator 102 may store one or more thresholds associated with a particular ablation instrument and may further provide a user interface that allows the user to select the connected ablation instrument. Additionally or alternatively, the ablation instrument may store identification information (e.g., model number, serial number, or identification) therein (e.g., in a memory chip or RFID chip) that the RF electrosurgical generator 102 may retrieve and look up the appropriate threshold in a table or database file.

[0094] In some situations, the measured impedance value 138 may not rise high enough to reach the impedance threshold 140. In such situations, other values ​​may be used to trigger the voltage amplitude reduction. In one example, the voltage amplitude may be reduced (e.g., to zero) based on a predetermined voltage threshold 136A. In another example, the voltage amplitude may be reduced (e.g., to zero) based on a predetermined amount of time 136B. Furthermore, both the predetermined voltage threshold 136A and the predetermined amount of time 136B may be used to reduce the voltage amplitude (e.g., to zero). In this regard, FIGS. 3 and 4 illustrate a schematic of a maximum voltage pulse 136.

[0095] In some examples, the time intervals between the voltage pulses 134 are a predetermined time period. In other examples, each of the voltage pulses 134 begins at a uniform start time relative to the start of the voltage train burst 130. In such examples, non-uniform intervals may be provided based on when the constant impedance value 138 reaches the impedance threshold 140.

[0096] In one example, the RF electrosurgical generator 102 may perform the following method: increase the voltage amplitude of RF energy delivered to one or more surgical instruments in a wet field environment, measure a measured impedance value 138 of the RF energy (e.g., simultaneously with the voltage amplitude increase), and reduce the voltage amplitude (e.g., to zero) when 1) the measured impedance value 138 reaches an impedance threshold 140, and 2) a predetermined voltage threshold 136A or a predetermined time 136B is reached. After a period of time (e.g., a predetermined amount of time), the cycle begins again to create multiple voltage pulses 134 as part of a voltage train burst 130.

[0097] The method or algorithm may generate many rapid voltage increases that typically achieve cavitation sparks while maintaining a relatively low duty cycle, thus enabling desirable tissue ablation in a moist environment while maintaining relatively low excess heat generation (e.g., heat in adjacent tissue other than the tissue cells being ablated).

[0098] The cutting instrument may also include a temperature sensor 163 on or near the electrode, which may transmit a temperature reading / data to the RF electrosurgical generator 102. The RF electrosurgical generator 102 may display this temperature reading on the display 104. The RF electrosurgical generator 102 may also include an audio and / or visual alarm that issues a warning when the measured temperature reading exceeds a predetermined threshold.

[0099] The RF electrosurgical generator 102 may also interrupt or adjust the RF energy output based on a predetermined temperature threshold. For example, the RF energy output may be stopped completely or the duty cycle may be altered (e.g., reduced).

[0100] The RF electrosurgical generator 102 may also be configured to deliver fluid at timed intervals. In one example, a dextrose solution or similar fluid may be delivered near or onto one or more electrodes of the cutting instrument to enhance conductivity or other properties. This fluid delivery may be timed to occur only when power is supplied to the electrodes (e.g., during a voltage train burst 130).

[0101] The RF electrosurgical generator 102 may limit the timing of RF energy output (e.g., voltage pulses 134) to the active electrode of the surgical instrument by monitoring the patient's heart and applying RF energy output only to specific portions of the patient's cardiac cycle that are shorter than the patient's entire cardiac cycle. This monitoring may include monitoring the patient's ECG reading. The RF electrosurgical generator 102 may be configured to connect directly to ECG leads to measure and record ECG data (e.g., via one or more outputs 106), or the RF electrosurgical generator 102 may connect to a separate ECG machine and receive ECG data from the ECG machine in real time during the procedure. The RF electrosurgical generator 102 may include software stored in non-transitory memory and executed by a processor that analyzes the ECG data to determine the patient's cardiac cycle phase, compares the patient's cardiac cycle phase to predetermined timing settings for the RF energy output (i.e., at which portion of the cardiac cycle the RF energy should be applied according to the ECG reading), and then delivers RF energy only at times in the cardiac cycle specified by the predetermined timing settings for the RF energy.

[0102] 5 shows an ECG graph of voltage versus time illustrating a patient's cardiac cycle. In this example, voltage train burst 130 is activated during the QRS complex of the patient's cardiac cycle, although any combination of measured ECG waves may be used, such as P, Q, R, S, T, and / or U, and the intervals therebetween. In another example, one or more of specific portions of the cardiac cycle, such as P, Q, R, S, T, and / or U, and the intervals therebetween, may be avoided.

[0103] The RF electrosurgical generator 102 may include a user interface that allows the user to select the portion of the cardiac cycle that may be activated for ablation, including the entire cardiac cycle.

[0104] Different phases of the cardiac cycle can result in different cardiac motion and blood flow volumes depending on the location of the active electrode of the ablation instrument. Therefore, limiting the ablation time to deliver RF energy to specific portions of the patient's cardiac cycle may result in more reliable tissue ablation.

[0105] In one example, the anterior leaflet of the mitral valve may be ablated to minimize the risk of left ventricular outflow tract obstruction. If the ablation instrument is held on the ventricular side of the mitral annulus plane with the active electrode facing the anterior leaflet, RF energy may be delivered to the active electrode as soon as the generator detects the onset of systole (by looking for the 'QRS complex'). Thus, power delivery is delivered with each heartbeat (minimizing total RF energy delivery).

[0106] In another example, the aortic valve leaflets may be ablated to minimize the risk of coronary artery occlusion due to TAVR implantation, similar to ablation of mitral valve leaflet tissue, but the surgeon may wish to apply RF ablation energy only during diastole.

[0107] In another example, cardiac valve leaflet clips (e.g., Mitraclip) may need to be removed, but may be fused to or in close proximity to the chordae tendineae. If these chordae need to be resected, this resection process can be difficult because the chordae are in motion throughout the cardiac cycle. Therefore, timing the delivery of RF energy to coincide with the time in the cardiac cycle when the chordae are approaching the active electrode may be advantageous for minimizing RF energy delivery time and further ablating the necessary tissue.

[0108] In another example, a slit may be made in the atrial septum to allow a large-bore catheter to cross without the need for balloon dilation. During a transseptal crossing procedure, there is a risk that the operator may advance the needle too far into the left atrium during the puncture. This may occur because the needle bounces or requires more forward pressure than expected to achieve the puncture. When creating a puncture and / or slit for large-bore catheter insertion, applying RF energy and ablating tissue only when the left atrium is at its maximum size (early ventricular diastole) may help minimize the risk of accidental perforation or extra-atrial ablation.

[0109] 6 shows a side view of one example of a leaflet treatment device removal system 150 that may be used to remove a leaflet clip or similar device from a patient's heart. Generally, the monopolar leaflet treatment device removal system 150 may include a capture basket catheter 152, a snare catheter 154, and a resecting loop catheter 156.

[0110] The capture basket catheter 152 may include an elongated catheter located at or near its distal end and having a basket sized to encompass the cardiac valve treatment device. The snare catheter 154 may include an elongated catheter located at or near its distal end and having a clampable loop used to capture the cardiac valve treatment device. The resection loop catheter 156 may include an elongated catheter located at or near its distal end and having a resection loop including one or more electrodes. The proximal end may include an electrical cable that can connect to one or more outputs 106 of the RF electrosurgical generator 102 to provide RF energy to the valve leaflet treatment device removal system 150. The valve leaflet treatment device removal system 150 may be monopolar or bipolar (e.g., used with pad electrodes 108).

[0111] In FIG. 10 , the capture basket catheter 152, snare catheter 154, and distal portions of the resecting loop catheter 156 are positioned below or on the ventricular side of the leaflet clip 40 connected to the heart valve leaflet 20. In FIG. 11 , the snare catheter 154 may be positioned around and tightened around the leaflet clip 40, and the leaflet clip 40 may be pulled toward or into the basket of the capture basket catheter 152. The resecting loop of 156 is positioned between the leaflet clip 40 and the heart valve leaflet 20. When the RF electrosurgical generator 102 is activated, one or more electrodes on the resecting loop of the resecting loop catheter 156 resect the heart valve leaflet 20 and any other tissue necessary to remove the leaflet clip 40, after which the leaflet clip 40 is retracted into the basket of the capture basket catheter 152. Details of this device, its variations, and methods of use are described in PCT / US2023 / 060773, which is incorporated herein by reference.

[0112] FIG. 7 shows a diagram of a resecting loop 160 including only a single electrode 162 and adjacent insulating portion 164 located at the distal end of the resecting loop 160. The resecting loop 160 may be used in a monopolar configuration. FIGS. 8 and 9 show diagrams of a resecting loop 166 having multiple electrodes 162A, 162B, 162C. While three electrodes are shown, two, three, four, five, six, seven, eight, or more electrodes are possible. The electrodes may be positioned at various locations around the resecting loop 166, such as intermediate and lateral positions. The resecting loop 160 may also include a temperature sensor, as previously described herein, that allows the RF electrosurgical generator 102 to monitor the temperature near the electrode.

[0113] FIG. 12 shows an example of a resecting loop device 170 having a hook, "C," or open loop shape 172 at the end of an elongated shaft 174. This curved shape may lie substantially in a single plane or may be non-planar and spiral. The inner surface 172A may include one or more electrodes, the outer surface may include one or more electrodes, or electrodes may encompass both the inner and outer surfaces. This shape may be particularly useful for use in resecting chordae tendineae in addition to tissue releasing cardiac valve treatment devices. Furthermore, the proximal end or cord may be connected to one or more outputs 106 of the RF electrosurgical generator 102 to create an electrical pathway to any electrode on the open loop shape 172.

[0114] 13 and 14 show a capturing member 180, which may be an elongated wire, multiple wires, a tubular structure, or a similar elongated structure, positioned within a lumen of a catheter body 182. In this example, the distal end of the capturing member 180 has a curved or spiral shape (e.g., either a spiral shape in a single plane or a helical / spiral shape) in an unconstrained state (a memory shape imparted to the shape-memory material). This memory shape may be used to encircle one or more chordae tendineae 21. The capturing member 180 may have at least a portion of its distal end uninsulated and electrically connected to the RF electrosurgical generator 102, or one or more electrodes 184 may be included in the distal portion of the capturing member 180.

[0115] 15 and 16 show another example of an RF guidewire 190 that may be advanced from a catheter or sheath 192. The RF guidewire 190 may be constructed of a shape-memory material, such as Nitinol, and may have a distal portion with a memory shape that forms a curled, coiled, or atraumatic "pigtail" shape when unconstrained. The RF guidewire 190 may be in electrical communication with the RF electrosurgical generator 102, allowing RF energy to be delivered to its distal portion. In this example, the RF guidewire 190 may pass through the septum 22 of the heart for a transseptal crossing procedure.

[0116] The RF electrosurgical generator 102 may further include software that monitors impedance to determine whether a cardiac valve treatment device, such as the aforementioned leaflet clip 40, is in contact with one or more electrodes of an instrument (e.g., the resection loop catheter 156). The RF electrosurgical generator 102 may compare the measured impedance value to a device contact impedance threshold and then generate an audio and / or video alert (e.g., on the display 104).

[0117] The RF electrosurgical generator 102 may further include software that monitors impedance to determine when tissue is in contact with one or more electrodes of the instrument (e.g., the resection loop catheter 156). The RF electrosurgical generator 102 may compare the measured impedance value to a tissue contact impedance threshold and then generate an audio and / or video alert (e.g., on the display 104).

[0118] In the case of monitoring the device contact impedance threshold and / or tissue contact impedance threshold, in cases where the ablation instrument includes multiple different electrodes on different circuits, the impedance of each electrode may be monitored separately and the RF electrosurgical generator 102 may indicate which electrode is in contact with the device or tissue.

[0119] As previously mentioned, the cutting instrument may include identification information (e.g., model number or serial number) that may be read by the RF electrosurgical generator 102, where this identification information is stored internally (e.g., on a memory chip or RFID chip). The software of the RF electrosurgical generator 102 may be configured to track the usage time of the cutting instrument. The software may also have a usage time threshold that, when exceeded, generates an audio and / or video alert indicating that the recommended lifetime usage time has been exceeded. Thus, the software may store or track the usage time of a particular cutting element; compare the usage time of the cutting element to a predetermined usage time threshold (e.g., by looking up the threshold based on the manufacturer / model identification), and then generate an alert when the threshold is exceeded. Similar thresholds may additionally or alternatively be used to measure usage time during a single procedure.

[0120] The software of the RF electrosurgical generator 102 may be further configured to monitor and compensate for changes in impedance caused, for example, by the buildup of necrotic tissue (eschar) on the electrode during the procedure or during use over the life of the ablation instrument. In one example, a small voltage (small enough not to induce heat generation at the electrode) may be applied to the active electrode during the relaxation period 132, and the resulting current may be measured. This allows the RF electrosurgical generator 102 to calculate the "small signal" electrode impedance. The RF electrosurgical generator 102 may track this value throughout the procedure and infer information regarding tissue buildup on the electrode. In another example, the RF electrosurgical generator 102 may track impedance "peaks" that occur during or immediately after the ablation operation and infer this information.

[0121] As previously mentioned, any of the resection instruments disclosed herein may include multiple electrodes that are independently wired (i.e., each forming a different circuit that can be independently activated), such as the resection loop catheter 156 of Figures 8 and 9. Such a multi-electrode resection loop may be connected to an RF electrosurgical generator 102 that can sense and energize these electrodes independently, allowing the user to determine when a particular electrode is in contact with tissue or blood and then specify which electrode should be electrically activated.

[0122] For example, FIG. 17 illustrates a contact interface 200 that can be displayed on the display 104 of the RF electrosurgical generator 102. The contact interface 200 may display information indicating which of multiple electrodes (e.g., electrodes 1, 2, and / or 3) is in contact with tissue and / or an implanted device. The tissue contact indication may be a graphical representation of a resection loop as shown in FIG. 17, a numeric display, or variations thereof. Tissue contact may be determined by continuously measuring an electrical value, such as impedance, of each electrode, and tissue contact may be determined to have occurred when the electrical value exceeds a certain threshold.

[0123] FIG. 18 shows an electrode activation interface 202 that allows a user to determine which electrodes will be electrically active when RF power is delivered to a resection instrument (e.g., a resection loop). The electrode activation interface 202 may be a graphical display of the resection loop as seen in FIG. 18, a numerical display, or variations thereof. The display may also include a sign, symbol, word, or other display element indicating whether the electrode is active or inactive. Furthermore, the activation display and tissue contact display may be combined on the same screen to display data simultaneously. The software of the RF electrosurgical generator 102 may first display the electrode activation interface 202, then allow the user to select the electrodes to be activated, information corresponding to the selected electrodes is stored in memory, and the software may then deliver RF energy only to the selected electrodes of the resection instrument.

[0124] It should be emphasized that any of the embodiments discussed in this application may be applied in combination, and although some embodiments are described separately from other embodiments, any combination of these features is specifically contemplated.

Claims

1. 1. An RF electrosurgical system comprising: an RF electrosurgical generator including a user interface and one or more outputs for supplying RF energy to an RF ablation instrument connected thereto, said RF electrosurgical generator comprising: measuring impedance values ​​while applying a plurality of voltage pulses to the ablation instrument; 10. An RF electrosurgical system comprising: a first RF electrode connected to a first power supply; a second RF electrode connected to a first power supply; a third RF electrode connected to a second power supply; a fourth RF electrode connected to a second power supply; a fifth RF electrode connected to a second power supply;

2. The RF electrosurgical system of claim 1 , wherein the impedance threshold is in the inclusive range of about 500 ohms to about 2000 ohms.

3. The RF electrosurgical system of claim 1 , wherein the impedance threshold is a predetermined threshold or a percentage impedance increase.

4. The RF electrosurgical system of claim 1 , wherein the impedance threshold is looked up in a database stored in memory of the RF electrosurgical generator based on a cutting instrument model number, serial number, or identification.

5. 2. The RF electrosurgical system of claim 1, wherein the software is further configured to partially or completely reduce the voltage amplitude of each of the plurality of voltage pulses if a predetermined voltage amplitude threshold for one of the plurality of pulses is exceeded and / or a predetermined pulse time threshold for the one of the plurality of pulses is exceeded.

6. The RF electrosurgical system of claim 1 , wherein the time intervals between the plurality of pulses are non-uniform.

7. The RF electrosurgical system of claim 1 , wherein the plurality of voltage pulses are arranged in bursts separated by relaxation periods.

8. The RF electrosurgical system of claim 1 , wherein the RF energy alternates within the inclusive range of about 4 and 5 megahertz.

9. The RF electrosurgical system of claim 1 , wherein the RF energy alternating at 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5.0 megahertz.

10. The RF electrosurgical system of claim 1 , wherein the RF energy is generated at a duty cycle of about 1% to about 20%.

11. The RF electrosurgical system of claim 1 , wherein the RF electrosurgical generator prevents generation of multiple voltage pulses during one or more of atrial diastole, atrial systole, ventricular diastole, and / or ventricular systole.

12. The RF electrosurgical system of claim 1 , wherein the software is configured to monitor ECG data and limit the RF energy to only a portion of a patient's cardiac cycle, but not all of it.

13. The RF electrosurgical system of claim 1 , wherein the software displays a user interface configured to select which portion of the patient's cardiac cycle receives the RF energy.

14. The RF electrosurgical system of claim 1 , wherein the ablation instrument is a leaflet treatment device removal system.

15. The RF electrosurgical system of claim 1 , wherein the cutting instrument is a loop containing one or more electrodes.

16. The RF electrosurgical system of claim 1 , wherein the cutting instrument is a resection loop catheter including multiple electrodes, each electrode having a separate electrical pathway in communication with the RF electrosurgical generator.

17. The RF electrosurgical system of claim 1 , wherein the software is configured to monitor temperature readings from the cutting instrument and prevent the RF energy when the temperature readings exceed a predetermined temperature threshold.

18. The RF electrosurgical system of claim 1 , wherein the ablation instrument is an RF guidewire having a distal portion that forms a coiled shape in an unconstrained state.

19. 10. The RF electrosurgical system of claim 1, wherein the software is configured to measure impedance from the ablation instrument, compare it to a tissue contact impedance threshold, and alert a user of tissue contact when the tissue contact impedance threshold is exceeded.

20. 10. The RF electrosurgical system of claim 1, wherein the software is configured to measure impedance from the ablation instrument, compare it to a device contact impedance threshold, and alert a user of tissue contact when the device contact impedance threshold is exceeded.

21. The RF electrosurgical system of claim 1 , wherein the software is configured to measure the duration of use of the cutting instrument.

22. 1. A method of operating an RF electrosurgical system, comprising: executing software on an RF electrosurgical generator including a user interface and one or more outputs for supplying RF energy to an RF ablation instrument connected thereto; measuring impedance values ​​with the RF electrosurgical generator while providing a plurality of voltage pulses to the cutting instrument; partially or completely reducing the voltage amplitude of each of a plurality of voltage pulses at the RF electrosurgical generator when the measured impedance value exceeds an impedance threshold; A method comprising:

23. 1. An RF electrosurgical system comprising: an RF electrosurgical generator including a user interface and one or more outputs for supplying RF energy to an RF ablation instrument connected thereto, said RF electrosurgical generator comprising:

1. An RF electrosurgical system executing software configured to prevent delivery of the RF energy to the ablation instrument during one or more of atrial diastole, atrial systole, ventricular diastole, and / or ventricular systole.

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