Organizational change system, method and signal generator for use with the organization change system - Patents.com

Abstract

A tissue treatment system and method are disclosed. In one embodiment, the tissue treatment system includes an LV signal generator, an HV signal generator, and a controller. The LV signal generator is used to generate an LV tissue impedance measurement signal, and the HV signal generator is used to generate an HV tissue treatment signal having a voltage at least 5 times greater than a voltage of the LV tissue impedance measurement signal. The controller is configured to control timing of delivery of the HV tissue treatment signal generated using the HV signal generator and the LV tissue impedance measurement signal generated using the LV signal generator to patient tissue via active and return electrodes. The LV tissue impedance measurement signal is used to estimate the impedance of the patient tissue, which is used to control the voltage and / or current of the HV tissue treatment signal.

Description

[Technical field]

[0001] Certain embodiments of the present technology relate to signal generators for use in treatment systems, such as tissue modification systems, and treatment systems including signal generators. Certain embodiments of the present technology further relate to methods used by and / or in conjunction with the signal generators and / or treatment systems including the signal generators.

[0002] This application claims priority to U.S. patent application Ser. No. 17 / 587,844, filed Jan. 28, 2022, which is incorporated herein by reference. [Background technology]

[0003] Pulsed electric field therapy (PEF) is used to deliver short pulses at high voltages to affect various diseased tissues such as luminal structures (airways, digestive tract), non-resectable tissue targets (liver, pancreas, lungs, kidneys), or cancerous solid tumors. However, when PEF therapy is performed using delivered voltage as a targeted therapeutic index, significant differences in patient outcomes can occur. This is at least due to inter-patient and inter-session variability. In this context, a session refers to a period during which a patient is treated under generally consistent exogenous factors. Thus, inter-session variability can include different patients and different patient conditions. Inter-patient and inter-session variability can result from differences in a number of factors, including hydration status, gender, blood pressure, placement of dispersive electrode pads, skin thickness, hair at the dispersive electrode site, substances delivered to the patient locally or systemically, and many other factors. It would be beneficial if PEF therapy, and more generally HV tissue therapy, could be controlled to account for both inter-patient and inter-session variability. Summary of the Invention [Problem to be solved by the invention]

[0004] Disclosed herein are tissue treatment systems and methods that can be used to deliver HV tissue treatment signals that account for both patient-to-patient and session-to-session variability. [Means for solving the problem]

[0005] In certain embodiments, the tissue treatment system includes an LV signal generator, an HV signal generator, and a controller. The LV signal generator is used to generate an LV tissue impedance measurement signal, and the HV signal generator is used to generate an HV tissue treatment signal having a voltage at least 5 times greater than the voltage of the LV tissue impedance measurement signal. The controller controls the timing of delivery of the HV tissue treatment signal generated with the HV signal generator and the LV tissue impedance measurement signal generated with the LV signal generator to the patient tissue via the active and return electrodes. The LV tissue impedance measurement signal is used to estimate the impedance of the patient tissue, and the impedance of the patient tissue is used to control the voltage and / or current of the HV tissue treatment signal.

[0006] According to certain embodiments, the tissue treatment system also includes a current sense circuit configured to measure a current delivered to the patient tissue via the active electrodes while an LV tissue impedance measurement signal generated using the LV signal generator is delivered to the patient tissue. In certain such embodiments, the controller is further configured to determine an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the current measured by the current sense circuit, and to control the voltage of the HV tissue treatment signal generated using the HV signal generator based on the estimate of the impedance of the patient tissue.

[0007] In certain embodiments, the control device is configured to control a voltage of an HV tissue treatment signal generated using the HV signal generator based on an estimate of the impedance of the patient tissue, such that when the HV tissue treatment signal is delivered to the patient tissue, the patient tissue is treated with a current approximately equal to a predetermined target current.

[0008] In certain embodiments, the controller is configured to generate an LV tissue impedance measurement signal delivered to the patient tissue using an LV signal generator between multiple separate instances of generating the HV tissue treatment signal delivered to the patient tissue using the HV signal generator. The controller is also configured to determine an updated estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on an updated measurement of the current delivered to the patient tissue measured using the current sense circuit. The controller is further configured to adjust the voltage of the HV tissue treatment signal generated using the HV signal generator if the updated estimate of the impedance of the patient tissue differs from a previous estimate of the impedance of the patient tissue, such that the next time the HV tissue treatment signal is delivered to the patient tissue, the patient tissue is treated with a current approximately equal to the predetermined target current.

[0009] According to certain embodiments, the LV signal generator comprises an LV power supply and the HV signal generator comprises an HV power supply that is different from the LV power supply of the LV signal generator. In certain such embodiments, the LV signal generator comprises an LV wave shaping circuit connected between the LV power supply and the active and return electrodes, and the HV signal generator comprises an HV wave shaping circuit connected between the HV power supply and the active and return electrodes, the HV wave shaping circuit being different from the LV wave shaping circuit. Alternatively, the LV signal generator and the HV signal generator share the same wave shaping circuit.

[0010] According to certain embodiments, the tissue treatment system further comprises an LV current sense circuit configured to measure a current delivered to the patient tissue via the active electrodes while an LV tissue impedance measurement signal generated using the LV signal generator is delivered to the patient tissue. The tissue treatment system may also comprise an HV current sense circuit distinct from the LV current sense circuit, the HV current sense circuit configured to measure a current delivered to the patient tissue via the active electrodes while an HV tissue treatment signal generated using the HV signal generator is delivered to the patient tissue. In certain such embodiments, the controller is further configured to determine an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the current measured by the LV current sense circuit. The controller is also configured to set the voltage of the HV tissue treatment signal generated using the HV signal generator based on the estimate of the impedance of the patient tissue. The controller is further configured to adjust the voltage of the HV tissue treatment signal generated using the HV signal generator based on the current measured by the HV current sense circuit.

[0011] A tissue treatment system according to certain embodiments includes a pair of electrodes, a plurality of capacitors, a power source, a waveform shaping circuit, and a controller. The power source is configured to charge the plurality of capacitors. The waveform shaping circuit is connected between the plurality of capacitors and the pair of electrodes. The controller is configured to connect a first subset of the capacitors to the waveform shaping circuit during a first time period when the LV tissue impedance measurement signal is delivered to the patient tissue via the pair of electrodes, and to connect a second subset of the capacitors to the waveform shaping circuit during a second time period when the HV tissue treatment signal is delivered to the patient tissue via the pair of electrodes. In certain such embodiments, a voltage of the HV tissue treatment signal is at least five times greater than a voltage of the LV tissue impedance measurement signal. The first subset of capacitors includes at least one of the plurality of capacitors. The second subset of capacitors includes at least one of the plurality of capacitors and is different from the first subset.

[0012] According to certain embodiments, the power supply, the waveshaping circuitry, and a first subset of the capacitors are components of the LV signal generator used to generate the LV tissue impedance measurement signal. The power supply, the waveshaping circuitry, and a second subset of the capacitors are components of the HV signal generator used to generate the HV tissue treatment signal. In such embodiments, the power supply and the waveshaping circuitry are shared by both the LV signal generator and the HV signal generator.

[0013] According to certain embodiments, the pair of electrodes comprises an active electrode and a return electrode, and the tissue treatment system further comprises a current sense circuit configured to measure a current delivered to the patient tissue via the active electrode while the LV tissue impedance measurement signal is delivered to the patient tissue. In certain such embodiments, the controller is further configured to determine an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the current measured by the current sense circuit. The controller is further configured to control the voltage of the HV tissue treatment signal based on the estimate of the impedance of the patient tissue.

[0014] According to certain embodiments, the method includes: (a) generating an LV tissue impedance measurement signal and transmitting the LV tissue impedance measurement signal to patient tissue via the active electrodes and the return electrodes; (b) measuring a current transmitted to the patient tissue via the active electrodes while the LV tissue impedance measurement signal is transmitted to the patient tissue; (c) determining an estimate of the impedance of the patient tissue based on a voltage of the LV tissue impedance measurement signal transmitted to the patient tissue and based on the measured current; and (d) generating an HV tissue treatment signal and transmitting the HV tissue treatment signal via the active electrodes and the return electrodes, wherein the voltage of the HV tissue treatment signal is at least five times greater than the voltage of the LV tissue impedance measurement signal, and generating the HV tissue treatment signal includes controlling the voltage of the HV tissue treatment signal based on the estimate of the impedance of the patient tissue.

[0015] In certain embodiments, steps (a), (b), (c) and (d) are performed in this order and, after being performed in this order, are repeated in this order, with step (c) being repeated to obtain an updated estimate of the impedance of the patient tissue and step (d) being repeated to control the voltage of the HV tissue treatment signal based on the updated estimate of the impedance of the patient tissue.

[0016] According to certain embodiments, steps (a), (b), (c) and (d) are performed in this order, and after being performed in this order, steps (a), (b) and (c) are repeated in this order to obtain an updated estimate of the impedance of the patient tissue. In certain such embodiments, the method further includes determining whether the treatment of the patient tissue was sufficient or whether additional treatment should be performed on the patient tissue in additional instances of step (d) based on the updated estimate of the impedance of the patient tissue.

[0017] According to certain embodiments, if an additional treatment is performed on the patient tissue in the additional instance of step (d), generating the HV treatment signal in the additional instance of step (d) includes controlling the voltage of the HV tissue treatment signal based on an updated estimate of the impedance of the patient tissue.

[0018] According to certain embodiments, generating the LV tissue impedance measurement signal in step (a) is performed using an LV signal generator, and generating the HV tissue treatment signal in step (c) is performed using an HV signal generator that is different from the LV signal generator.

[0019] According to certain embodiments, the method further includes charging a plurality of capacitors using a power source and shaping the LV tissue impedance measurement signal and the HV tissue treatment signal using a wave shaping circuit connected between the plurality of capacitors and the active and return electrodes. In certain such embodiments, generating and transmitting the LV tissue impedance measurement signal in step (a) includes connecting a first subset of the capacitors to the wave shaping circuit during a first time period, and generating and transmitting the HV tissue treatment signal in step (c) includes connecting a second subset of the capacitors to the wave shaping circuit during a second time period. The first subset of capacitors includes at least one of the plurality of capacitors and the second subset of capacitors includes at least one of the plurality of capacitors and is different from the first subset.

[0020] The above summary is not intended to be a complete description of embodiments of the present technology. Other features and advantages of embodiments of the present technology will become apparent from the following description, in which preferred embodiments are set forth in detail, taken in conjunction with the accompanying drawings and claims. [Brief description of the drawings]

[0021] [Figure 1A] 1 illustrates an exemplary treatment system for use in treating a patient.

[0022] [Figure 1B] FIG. 1B is a schematic diagram of an embodiment of a treatment system first introduced in FIG. 1A.

[0023] [Diagram 2] FIG. 2 is an exemplary circuit diagram of an output signal generating circuit of the signal generator introduced in FIGS. 1A and 1B.

[0024] [Diagram 3] 1 illustrates an embodiment of a biphasic treatment signal waveform defined by an energy delivery algorithm.

[0025] [Figure 4]3 shows the signals generated by the controller of the circuit introduced in FIG. 2 that are used to control the switches to generate a biphasic therapy signal.

[0026] [Figure 5A] 1C is a high-level block diagram of an output signal generator of the signal generator introduced in FIGS. 1A and 1B in accordance with an embodiment of the present technique. FIG.

[0027] [Figure 5B] FIG. 2 is a high level block diagram of an output signal generator in accordance with another embodiment of the present technique.

[0028] [Figure 5C] FIG. 13 is a high level block diagram of an output signal generator in accordance with a further embodiment of the present technique.

[0029] [Figure 5D] FIG. 13 is a high level block diagram of an output signal generator in accordance with yet another embodiment of the present technique.

[0030] [Figure 6] FIG. 1 is a high-level flow diagram used to explain a method in accordance with certain embodiments of the present technology. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031] Certain embodiments of the present technology relate to, but are not limited to, signal generators for use in treatment systems, such as tissue modification systems. FIG. 1A illustrates an exemplary treatment system 100 for use in treating a patient. FIG. 1B is a schematic diagram of the embodiment of the treatment system shown in FIG. 1A. In this embodiment, the system 100 includes a treatment energy delivery instrument 102 (e.g., a catheter) connectable to a signal generator 104, also referred to herein more simply as a generator 104. With reference to FIG. 1A, the instrument 102 is shown as having an elongated shaft 106 having at least one delivery electrode 108 near its distal end 124 and a handle 110 disposed at its proximal end 128. The instrument 102 is connectable to the generator 104 as part of the treatment system 100. Connecting the instrument 102 to the generator 104 provides electrical energy to the delivery electrode 108, among other features. In this embodiment, the delivery electrode 108 is shown as a cylindrically shaped "solid tip" electrode having a continuous surface at the distal end. In some embodiments, the cylindrical shape has a diameter of about 2-3 mm at the distal face and a length along the shaft 106 of about 1 mm, 2 mm, 1-2 mm, 3 mm, 4 mm, 3-4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, etc. It will be understood that such electrodes are normally hollow, but are referred to as solid due to their visual appearance. In some embodiments, the total length of the catheter 102 is 50-150 cm, preferably 100-125 cm, more preferably 110-115 cm. Similarly, in some embodiments, the catheter 102 has an outer diameter of 3-15 Fr, preferably 4-12 Fr, more preferably 7-8.5 Fr. Deflection of the shaft 106 may be achieved by various mechanisms, such as pull wires extending to the handle 110. Thus, the handle 110 is used to manipulate the catheter 102, particularly the distal end, during delivery and treatment. Energy is supplied to the catheter 102, and thus to the delivery electrode 108, via a cable 130 that is connectable to the generator 104. In some embodiments, the handle 110 is removable, such as by pressing a handle removal button.Herein, the energy delivery electrodes 108 are sometimes referred to as active electrodes 108. It will be appreciated that various types of visualization may be used, such as angiography (optionally including markers), computed tomography, optical coherence tomography, ultrasound, and direct video visualization.

[0032] A pulsed electric field (PEF) is provided by the generator 104 and delivered to the tissue via a delivery electrode 108 placed on or near the target tissue region. It will be appreciated that in some embodiments, the delivery electrode 108 is placed in contact with a conductive material that is also in contact with the target tissue. Such solutions include isotonic or hypertonic solutions. Such solutions may further include ancillary substances such as chemotherapy or calcium to further enhance the therapeutic effect on both the local treatment as well as potential local invasion areas of the target tissue type. High voltage, brief biphasic electrical pulses are then delivered via the electrode 108 in the vicinity of the target tissue. These electrical pulses are provided by at least one energy delivery algorithm 152. In some embodiments, each energy delivery algorithm 152 defines a signal having a waveform that comprises a series of energy packets, each energy packet including a series of high voltage pulses. In such embodiments, the algorithm 152 defines parameters of the signal such as the energy amplitude (e.g., voltage) and duration of the applied energy, the signal being comprised of, for example, the number of packets, the number of pulses within the packet, and the fundamental frequency of the pulse train. Other parameters include switch time between polarities in a biphasic pulse, dead time between biphasic cycles, and pause time between packets, which are described in more detail below. The pause time between packets may be constant or may vary with the patient's heart rate by gating the packets to the cardiac cycle. There may be algorithms that purposefully vary the pause time, or there may be no pause time between packets. Feedback loops based on sensor information and automatic shutoff features, etc. may also be included.

[0033] It will be appreciated that in various embodiments, the catheter 102 includes various specialized features. For example, in some embodiments, the catheter 102 includes a mechanism for measuring in real time the contact force that the catheter tip exerts on the patient's heart wall during the procedure. In some embodiments, this mechanism is housed within the shaft 106 and includes a three-axis optical force sensor that utilizes white light interferometry. By monitoring and varying the force exerted during the procedure, the user can have greater control over the catheter 102 and create more uniform and effective lesions. Other types of contact force sensors may also be used and are within the scope of the embodiments described herein.

[0034] In this embodiment, the therapeutic energy delivery device 102 is connectable to the generator 104 with a dispersive electrode 140 that is externally attached to the patient's skin. Thus, in this embodiment, monopolar energy delivery is achieved by providing energy between the energy delivery electrode 108 located near the distal end of the device 102 and the dispersive electrode 140. The dispersive electrode 140 is also referred to herein as the return electrode 140. However, it will be understood that alternatively, bipolar energy delivery and other configurations may be used. When using bipolar energy delivery, the overall design of the therapeutic energy delivery device 102 may be different, such as the therapeutic energy delivery device 102 including multiple energy delivery electrodes 108, or the overall design of the therapeutic energy delivery device 102 may be similar, such as the therapeutic energy delivery device 102 including a single energy delivery electrode 108 configured to function bipolarly. In some embodiments, the return electrode 140 is an embedded electrode located, for example, but not limited to, on the catheter 102 or on a sheath. In some instances, bipolar energy delivery requires lower voltages to achieve a therapeutic effect compared to monopolar energy delivery. In a bipolar configuration, the positive and negative electrodes are in close enough proximity to provide a therapeutic effect both at the electrode poles and between the electrode poles. This allows the therapeutic effect to be delivered over a broad and shallow surface area, so a lower voltage is required to achieve a therapeutic effect compared to monopolar. Furthermore, this lower voltage may be used to reduce the penetration depth. Additionally, the lower voltage may obviate the need for myocardial synchronization, provided that the delivered voltage is low enough to avoid trapping of myocardial cells.

[0035] In this embodiment, the generator 104 comprises a user interface 150, one or more energy delivery algorithms 152, a processor 154, a data storage / retrieval unit 156 (such as a memory and / or database), and an output signal generation circuit 158 ​​that generates and / or stores the energy to be delivered and generates the desired waveform of the delivered energy. In some embodiments, one or more capacitors are used to store / deliver the energy, although any other suitable energy storage elements may be used. In some embodiments, various switches are used to generate the desired waveform of the delivered energy. Additionally, one or more communication ports 167 may be included.

[0036] In some embodiments, the generator 104 comprises three subsystems: 1) a high energy storage system; 2) a high voltage, mid frequency switching amplifier; and 3) a system controller, firmware, and user interface. The system controller includes a cardiac synchronization trigger monitor that can synchronize the pulsed energy output to the patient's cardiac rhythm. The generator takes in an alternating current (AC) line and provides power to multiple direct current (DC) sources. The generator controller may cause the DC sources to charge a high energy capacitor storage string before energy delivery begins. At the start of therapeutic energy delivery, the generator controller, high energy storage string, and biphasic pulse amplifier operate simultaneously to produce a high voltage, mid frequency output.

[0037] It will be appreciated that numerous generator electrical architectures may be employed to implement the energy delivery algorithms. In particular, some embodiments use advanced switching systems that can direct the pulsed electric field circuitry to the energy delivery electrodes separately from the same energy storage and high voltage delivery system. Additionally, generators employed with advanced energy delivery algorithms employing rapidly changing pulse parameters (e.g., voltage, frequency, etc.) or multiple energy delivery electrodes may utilize modular energy storage devices and / or high voltage systems, facilitating highly customizable waveform and geographic pulse delivery paradigms. Additionally, it should be appreciated that the electrical architectures described herein above are merely exemplary, and that the systems delivering the pulsed electric fields may or may not include additional switching amplifier components.

[0038] The user interface 150 may include a touch screen and / or conventional buttons to allow an operator to input patient data, select a treatment algorithm (e.g., energy delivery algorithm 152), initiate energy delivery, review records stored in the storage / retrieval unit 156, and / or communicate with the generator 104. The user interface 150 may include a voice activation mechanism for inputting patient data, or may be capable of communicating with other devices in the room such that control of the generator 104 is via a secondary, separate user interface.

[0039] In some embodiments, the user interface 150 is configured to receive operator-defined inputs. The operator-defined inputs may include duration of energy delivery, one or more other timing aspects of the energy delivery pulse, power, and / or mode of operation, or combinations thereof. Exemplary modes of operation may include, but are not limited to, system initiation and self-test, operator input, algorithm selection, pre-treatment system status and feedback, tissue impedance measurement, energy delivery, display or feedback after energy delivery, review and / or download of treatment data, software update, or any combination or subcombination thereof. According to certain embodiments, the user interface 150 displays information to a physician or technician, or other user, during automated treatment delivery, in which all of the aforementioned administration parameters (e.g., duration of energy delivery, one or more other timing aspects of the energy delivery pulse, power, and / or mode of operation, or combinations thereof) can be pre-set. The user interface 150 may be used to provide system status after one or more self-tests and may provide a way for a user to review system status information. The user interface 150 may also be used to select or specify a target current and / or a target voltage to be used for treatment.

[0040] In some embodiments, the system 100 also includes a mechanism for acquiring an electrocardiogram (ECG), such as an external cardiac monitor 170. An exemplary cardiac monitor is available from AccuSync Medical Research Corporation. In some embodiments, the external cardiac monitor 170 is operatively connected to the generator 104. The cardiac monitor 170 may be used to continuously acquire an ECG signal. External electrodes 172 may be attached to the patient to acquire the ECG. The generator 104 may synchronize energy delivery to the cardiac cycle by analyzing one or more cardiac cycles and identifying the beginning of a period during which it is safe to apply energy to the patient. In some embodiments, the period is within a few milliseconds of the R wave (of the ECG-QRS complex) to avoid induction of arrhythmias that may occur if the energy pulse is delivered at the T wave. It will be appreciated that such cardiac synchronization is typically used when using unipolar energy delivery, but may also be used as part of other energy delivery methods.

[0041] In some embodiments, the processor 154 changes and / or switches energy delivery algorithms, monitors energy delivery and sensor data, and reacts to the monitored data via a feedback loop, among other actions. In some embodiments, the processor 154 is configured to execute one or more algorithms for implementing a feedback control loop based on one or more measured system parameters (e.g., current), one or more measured tissue parameters (e.g., impedance), and / or a combination thereof.

[0042] The data storage / retrieval unit 156 stores data, such as data regarding treatments performed, which can optionally be downloaded by connecting a device (e.g., a laptop or thumb drive) to the communications port. In some embodiments, the device has local software used to direct the download of information, such as instructions stored in the data storage / retrieval unit 156 and executable by the processor 154. In some embodiments, the user interface 150 allows an operator to select to download data to a device and / or system, such as, but not limited to, a computing device, tablet, mobile device, server, workstation, cloud computing device / system, etc. Communications ports that allow wired and / or wireless connections allow for the downloading of data, as just described, but also for uploading data, such as uploading custom algorithms or providing software updates.

[0043] The data storage / retrieval unit 156 may be, for example, a random access memory (RAM), a memory buffer, a hard drive, a database, an erasable programmable read-only memory (EPROM), an electrically erasable read-only memory (EEPROM), a read-only memory (ROM), a flash memory, etc. The data storage / retrieval unit 156 may store instructions that cause the processor 154 to execute modules, processes, and / or functions associated with the system 100.

[0044] In some embodiments, the data storage / retrieval unit 156 comprises a computer storage product including a non-transitory computer readable medium (also referred to as a non-transitory processor readable medium) having instructions or computer code for performing various computer-implemented operations. The computer readable medium (or processor readable medium) is non-transitory in the sense that it does not itself include a transitory propagating signal (e.g., a propagating electromagnetic wave that conveys information over a transmission medium such as space or a cable). The medium and computer code (also referred to as code) may be designed and constructed for a specific purpose or purposes. Examples of non-transitory computer readable media include, but are not limited to, magnetic storage media such as hard disks, floppy disks, magnetic tapes, optical storage media such as compact disks / digital video disks (CD / DVD), compact disk read only memory (CD-ROM), holographic devices, magneto-optical storage media such as optical disks, carrier wave signal processing modules, hardware devices specially configured to store and execute program code, such as ASICs, programmable logic circuits (PLDs), read only memories (ROMs), random access memory (RAM) devices, and the like. Other embodiments described herein relate to computer program products that may include, for example, instructions and / or computer code described herein.

[0045] Examples of computer code include, but are not limited to, microcode or microinstructions, machine instructions such as those produced by a compiler, code used to create a web service, and files containing high-level instructions executed by a computer using an interpreter. For example, embodiments may be implemented using an imperative programming language (e.g., C, Fortran, etc.), a functional programming language (e.g., Haskell, Erlang, etc.), a logic programming language (e.g., Prolog), an object-oriented programming language (e.g., Java, C++, etc.), or other suitable programming language and / or development tools. Other examples of computer code include, but are not limited to, control signals, encryption code, compression code, etc.

[0046] In some embodiments, system 100 may be communicatively connected to a network, which may be any type of network, such as, for example, a local area network (LAN), a wide area network (WAN), a virtual network, a telecommunications network, a data network, and / or the Internet, implemented as a wired network and / or a wireless network. In some embodiments, any or all communications may be protected using any suitable type and / or method of secure communications (e.g., Secure Sockets Layer (SSL)) and / or encryption. In other embodiments, any or all communications may not be protected.

[0047] FIG. 1B is a schematic diagram of one embodiment of the treatment system 100 first introduced in FIG. 1A. In this embodiment, a dispersive (indifferent) or return electrode 140 is operably connected to the generator 104 and is also affixed to the patient's skin to provide a return path for energy delivered through the instrument 102. The energy delivery instrument 102 comprises one or more energy delivery electrodes 108, one or more sensors 160, one or more imaging modalities 162, one or more buttons 164, and / or a positioning mechanism 166 (e.g., but not limited to, a lever and / or dial on a handle with a pull wire, retractable tube, sheath, etc.) to bring the one or more energy delivery (active) electrodes 108 into contact with tissue. In some embodiments, a foot switch 168 is operably connected to the generator 104 and is used to initiate energy delivery. Herein, the dispersive electrode 140 is also referred to as the indifferent electrode 140, the return electrode 140, or more simply, the electrode 140.

[0048] As previously mentioned, the user interface 150 may include a touch screen and / or conventional buttons to allow an operator to input patient data, select a treatment algorithm 152, initiate energy delivery, review records stored in the storage / retrieval unit 156, or communicate with the generator 104. The processor 154 manages and executes the energy delivery algorithm, monitors energy delivery and any sensor data, and reacts to the monitored data via a feedback loop. The data storage / retrieval unit 156 stores data related to the treatment administered and can be downloaded by connecting a device (e.g., a laptop or thumb drive) to the communication port 167.

[0049] The instrument 102 is operatively connected to the generator 104 and / or a separate imaging screen 180. The imaging modality 162 may be integrated into the instrument 102 or may be used in parallel or simultaneously with the instrument 102. Alternatively or additionally, a separate imaging modality or device 169, such as a commercially available system (e.g., a bronchoscope), may be used. The separate imaging device 169 may be mechanically, operatively, and / or communicatively connected to the instrument 102 using any suitable mechanism.

[0050] 2 is an exemplary circuit diagram of one embodiment of the output signal generation circuit 158 ​​of the signal generator 104 described above in the description of FIGS. 1A and 1B. Referring to FIG. 2, the output signal generation circuit 158 ​​is shown to include a high voltage (HV) power supply 202, a controller 203, an HV capacitor 206, a bleed resistor 207, a wave shaping circuit 208, a voltage sense circuit 210, a voltage sense circuit 212, and a current sense circuit 214. As will be appreciated by those skilled in the art, the output signal generation circuit 158 ​​may include additional circuitry, not shown. For example, a step-up transformer, a filter, and / or a DC blocking capacitor may be optionally connected between the output nodes of the wave shaping circuit 208 (shown as OUT1 and OUT2) and the active electrode 108 and the return electrode 140. A step-up transformer may be used to step up the voltage signal generated between the output nodes of the wave shaping circuit 208 (between output 1 and output 2) to a desired level and to isolate the HV power supply 202 and the wave shaping circuit 208 from the electrodes 108, 140. A filter may be, for example, an RC snubber circuit including a resistor and a capacitor connected in series between the electrodes 108 and 140, which may be used to eliminate high frequency transients or ringing that may be caused by the leakage inductance of the transformer. A DC blocking capacitor may be used to prevent low frequency or direct current from inadvertently flowing into the patient tissue.

[0051] Continuing with reference to FIG. 2, the HV power supply 202 is configured to selectively provide a high voltage DC signal that is used to charge the HV capacitor 206 to a desired voltage level. In certain embodiments, a voltage sense circuit 210 may be used to determine when the HV capacitor 206 has been charged to the desired voltage level, but this is not required. The HV power supply 202 may include, for example, an AC / DC converter that takes an alternating current (AC) line and outputs a direct current (DC) signal. The HV power supply 202 may also include a step-up or step-down voltage regulator that receives the output of the AC / DC converter, converts the output of the AC / DC converter to the desired voltage level, and maintains the voltage level at the desired level. As will be appreciated by those skilled in the art, the HV power supply 202 may include additional and / or different circuits. A switch Sp is used to selectively connect the HV power supply 202 to the HV capacitor 206. Instead of (or in addition to) using switch Sp to control whether HV power source 202 charges HV capacitor 206, the output of HV power source 202 may be selectively enabled and disabled by controller 203, thereby selectively controlling whether HV capacitor 206 is charged by HV power source 202 at any given time. Thus, if the output of HV power source 202 is selectively enabled and disabled by controller 203, optionally switch Sp may not be present.

[0052] HV capacitor 206 comprises one or more HV capacitors used to store energy used to generate tissue treatment signals delivered to the patient via electrodes 108 and 140, or other electrodes. HV capacitor 206 may be implemented using a string of capacitors connected in series and / or in parallel with each other, depending on the particular implementation.

[0053] The bleed resistor 207 is used to selectively release all or a portion of the energy stored by the HV capacitor 206 by selectively turning on (i.e., closing) the switch S_bleed. For example, if the controller 203 determines using the voltage sense circuit 210 that the voltage stored by the HV capacitor 206 exceeds a desired level, the controller 203 may turn on (i.e., close) the switch S_bleed until the voltage stored by the HV capacitor 206 is reduced to the desired level, at which point the controller 203 may turn off (i.e., open) the switch S_bleed. Each of the switches Sp and S_bleed may be implemented using, but is not limited to, an insulated gate bipolar transistor (IGBT), another type of transistor, or a relay. The bleed resistor 207 may be implemented using a string of resistors connected in series and / or in parallel with each other, depending on the particular implementation. It is also possible to eliminate the bleed resistor and instead bleed off the excess voltage stored by the HV capacitor 206 into the patient tissue.

[0054] The wave shaping circuit 208 is shown as including current limiting resistors Ra1, Ra2, Rb1, and Rb2, and switches Sa1, Sa2, Sb1, and Sb2. These switches are controlled by a controller 203, which may be implemented by a processor (e.g., processor 154 in FIGS. 1A and 1B), a field programmable gate array (FPGA), or the like. According to a particular embodiment, each of the switches Sa1, Sa2, Sb1, and Sb2 is implemented using an insulated gate bipolar transistor (IGBT). If each of the switches is implemented using an IGBT, each switch may include or be associated with an IGBT driver (not shown), as will be understood by those skilled in the art. Each such IGBT driver may selectively turn on (i.e., close) or off (i.e., open) an IGBT-type switch in response to a signal received from the controller 203. Output nodes of the wave shaping circuit 208, designated OUT1 and OUT2, are connected to the active electrode 108 and the return electrode 140, respectively. Alternatively, if the circuit 158 ​​includes a step-up transformer, the output nodes of the wave shaping circuit 208, designated OUTPUT 1 and OUTPUT 2, may be connected to the primary side of the transformer, and the active electrode 108 and the return electrode 140 may be connected to the secondary side of the transformer. The aforementioned switches may alternatively be implemented using other types of transistors.

[0055] 3 illustrates one embodiment of a waveform 300 of a therapy signal defined by the energy delivery algorithm 152, which may be generated by selectively turning on and off various switches Sa1, Sa2, Sb1, and Sb2 under the control of the controller 203. The waveform 300 may also be referred to as a biphasic therapy signal 300, or more simply, a therapy signal 300. In FIG. 3, one packet 302 is shown. However, the waveform 300 may include one or more additional packets (not shown), with the packets and packets separated from each other by rest periods. In this embodiment, the packet 302 is composed of a first biphasic period (including a first positive pulse peak 308 and a first negative pulse peak 310), a second biphasic period (including a second positive pulse peak 308′ and a second negative pulse peak 310′), and an nth biphasic period (including an nth positive pulse peak 308″ and an nth negative pulse peak 310″), where n is an integer equal to or greater than 3. The first and second biphasic pulses are separated by a dead time 312 (i.e., pause) between the pulses. In this embodiment, the biphasic pulses are symmetric, so that the set voltage 316p of the positive peak is the same as the set voltage 316n of the negative peak, but this does not have to be the case. Here, the biphasic symmetric wave is also a square wave, where the magnitude and time of the positive voltage wave are approximately equal to the magnitude and time of the negative voltage wave, but this does not have to be the case.

[0056] When using a bipolar configuration to apply a treatment signal, a portion of the cells (e.g., airway wall cells) facing the negative voltage wave will experience cell depolarization, with the normally negatively charged cell membrane regions turning positive for a short period of time. Meanwhile, a portion of the cells facing the positive voltage wave will experience hyperpolarization, with the potential of the cell membrane regions becoming extremely negative. When used to treat airway walls in a patient's lungs, it will be appreciated that a portion of the airway wall cells will be affected in opposite ways during each positive or negative phase of the biphasic pulse. For example, a portion of the cell membrane facing the negative voltage will experience depolarization, while a portion at 180 degrees to this portion will experience hyperpolarization. In some embodiments, the hyperpolarized portion faces the dispersive or return electrode 140.

[0057] The HV tissue treatment signals described herein may be used to deliver therapeutic energy to portions of a patient's heart to cause tissue modification, such as, for example, the ostia of the pulmonary veins in atrial fibrillation (AF) treatment. Specific anatomical sites that may be targeted include the superior vena cava, the inferior vena cava, the right pulmonary veins, the left pulmonary veins, the right atrium, the right atrial appendage, the left atrium, the left atrial appendage, the right ventricle, the left ventricle, the right ventricular outflow tract, the left ventricular outflow tract, the interventricular septum, the left ventricular apex, the myocardial scar region, the myocardial infarction border region, the myocardial infarction channel, the ventricular endocardium, the ventricular epicardium, the papillary muscles, the Purkinje system, etc. Treatments may be performed at isolated sites or in a series of linked treatments. The types of treatments include left atrial roof line creation, left atrial anterior-posterior line, posterior wall separation, mitral lateral isthmus line, mitral septal isthmus line, left atrial appendage, right sinoatrial isthmus (CTI), pulmonary vein isolation, superior vena cava isolation, Marshallian vein, lesion creation using complex fractionated atrial electrogram (CFAE), lesion creation using focal impulse rotor modulation (FIRM), and targeted ganglion ablation. Such tissue modification creates a conduction block in the tissue to inhibit the transmission of abnormal electrical signals. The devices, systems, and methods are typically used in electrophysiology laboratories or controlled operating rooms with fluoroscopy and advanced electrocardiogram recording and monitoring capabilities. The primary user of the system is the electrophysiologist (EP). The electrophysiologist is supported by a staff of trained nurses, technicians, and possibly other electrophysiologists. Typically, the tissue modification system includes a specialized catheter, a high-voltage waveform generator, and at least one specific energy delivery algorithm.

[0058] The voltages that may be used may be the peaks of a square waveform, the peaks of a sine wave or sawtooth waveform, or the RMS voltage of a sine wave or sawtooth waveform. In some embodiments, the energy is delivered in a unipolar manner, and each high voltage pulse or set voltage 316 is between about 500V and 10,000V, in particular between about 500V and 5000V, between about 500V and 4000V, between about 1000V and 4000V, between about 2500V and 4000V, between about 2000V and 3500V, between about 2000V and 2500V, between about 2500V and 3500V, including all values ​​and subranges within the above mentioned ranges, such as about 500V, 1000V, 1500V, 2000V, 2500V, 3000V, 3500V, 4000V, etc. In some embodiments, each high voltage pulse is in the range of about 1000V to 2500V that can penetrate the airway wall W with a particular combination of parameters to treat or affect specific cells located somewhat shallower, such as epithelial cells. In some embodiments, each high voltage pulse is in the range of about 2500V to 4000V that can penetrate the airway W with a particular combination of parameters to treat or affect specific cells located somewhat deeper, such as submucosal cells or smooth muscle cells.

[0059] It will be appreciated that the set voltages 316p, 316n may vary depending on the particular implementation. With bipolar delivery, lower voltages may be used since the electric field is smaller and more directional. In some embodiments, the energy is delivered in a bipolar manner, with each pulse being in the range of about 100V to 1900V, particularly 100V to 999V, more particularly about 500V to 800V, such as, for example, 500V, 550V, 600V, 650V, 700V, 750V, 800V, etc. In other embodiments, the energy is delivered in a bipolar manner, with each pulse being between about 50 to 5000V, including 250 to 1500V.

[0060] While the voltage selected for bipolar treatment varies with the separation distance between the electrodes, a monopolar electrode configuration using separate dispersive pad electrodes allows delivery with less consideration given to the exact placement between the catheter electrode and the dispersive electrode on the body. In monopolar electrode embodiments, large voltages are typically used with effective separation distances of around 10 cm to 100 cm, due to the dispersive behavior of the energy as it travels through the body to the dispersive electrode. Conversely, in bipolar electrode configurations, the relatively close active area of ​​the electrodes, approximately 0.5 mm to 10 cm, including 1 mm to 1 cm, greatly impacts the concentration and effective amount of electrical energy delivered to the tissue from the separation distance. For example, if the target voltage-to-distance ratio is 3000 V / cm to produce the desired clinical effect at the appropriate tissue depth (1-3 mm), changing the separation distance from 1 mm to 1.2 mm would require an increase in treatment voltage from 300 V to approximately 360 V, a change of 20%.

[0061] The frequency is the number of biphasic cycles per second of time. In some embodiments, biphasic pulses are utilized to reduce undesirable muscle stimulation, particularly myocardial stimulation. In other embodiments, the pulse waveform is monophasic and does not have a well-defined inherent frequency, instead, a fundamental frequency may be considered by doubling the monophasic pulse length to derive the frequency. In some embodiments, the signal has a frequency in the range of 10 kHz to 10 MHz, more particularly in the range of 100 kHz to 1 MHz, more particularly in the range of 100 kHz to 1000 kHz. In some embodiments, the signal has a frequency in the range of about 100 to 600 kHz that typically penetrates the airway and treats or affects certain cells that are somewhat deeper, such as submucosal cells or smooth muscle cells. In some embodiments, the signal has a frequency in the range of about 600 kHz to 1000 kHz or 600 kHz to 1 MHz that typically penetrates the airway wall W and treats or affects certain cells that are somewhat shallower, such as epithelial cells. It will be appreciated that some voltages may cause undesired muscle stimulation at frequencies below 300 kHz. Thus, in some embodiments, the signal has a frequency in the range of 400-800 kHz or in the range of 500-800 kHz, such as 500 kHz, 550 kHz, 600 kHz, 650 kHz, 700 kHz, 750 kHz, 800 kHz, etc. In particular, in some embodiments, the signal has a frequency of 600 kHz. Furthermore, cardiac synchronization is typically used to reduce or avoid undesired myocardial stimulation during susceptible rhythm periods. It will be appreciated that even higher frequencies may be used with components that minimize signal artifacts.

[0062] FIG 4 illustrates signals for controlling switches Sa1, Sa2, Sb1, and Sb2 generated by the controller 203 of FIG 2 (e.g., processor 154 of FIG 1A and FIG 1B) to generate the biphasic therapy signal 300 shown in FIG 3. The aforementioned switches collectively provide a switching network. In FIG 4, phase 1 up signal 402 is used to control switch Sa1, phase 2 down signal is used to control switch Sa2, phase 2 up signal 406 is used to control switch Sb1, and phase 2 down signal 408 is used to control switch Sb2. 2, 3, and 4, during the period between time t1 and time t2, phase 1 up signal 402 turns on (i.e., closes) switch Sa1, phase 1 down signal 408 turns on (i.e., closes) switch Sb2, phase 2 down signal 404 keeps switch Sa2 off (i.e., leaves it open), and phase 2 up signal 406 keeps switch Sb1 off (i.e., leaves it open), which results in the first positive pulse peak 308 shown in FIG. 3.

[0063] During the period between time t2 and time t3, the phase 1 up signal 402 turns switch Sa1 off (i.e., opens), the phase 1 down signal 408 turns switch Sb2 off (i.e., opens), the phase 2 down signal 404 turns switch Sa2 on (i.e., closes), and the phase 2 up signal 406 turns switch Sb1 on (i.e., opens), which results in the first negative pulse peak 310 shown in Figure 3. During the period between time t3 and time t4, the phase 1 up signal 402 keeps switch Sa1 off (i.e., keeps open), the phase 1 down signal 408 keeps switch Sb2 off (i.e., keeps open), the phase 2 down signal 404 turns switch Sa2 off (i.e., opens), and the phase 2 up signal 406 turns switch Sb1 off (i.e., opens), which results in the dead time 312 after the first negative pulse peak 310 shown in Figure 3. During the time period between time t4 and time t5, the phase 1 up signal 402 turns on (i.e., closes) switch Sa1, the phase 1 down signal 408 turns on (i.e., closes) switch Sb2, the phase 2 down signal 404 keeps switch Sa2 off (i.e., leaves it open), and the phase 2 up signal 406 keeps switch Sb1 off (i.e., leaves it open), which results in the second positive pulse peak 308' shown in Figure 3. During the time period between time t5 and time t6, the phase 1 up signal 402 turns off (i.e., opens) switch Sa1, the phase 1 down signal 408 turns off (i.e., opens) switch Sb2, the phase 2 down signal 404 turns on (i.e., closes) switch Sa2, and the phase 2 up signal 406 turns on (i.e., opens) switch Sb1, which results in the second negative pulse peak 310' shown in Figure 3. During the period between time t6 and time t7, phase 1 up signal 402 keeps switch Sa1 off (i.e., leaves it open), phase 1 down signal 408 keeps switch Sb2 off (i.e., leaves it open), phase 2 down signal 404 turns switch Sa2 off (i.e., opens), and phase 2 up signal 406 turns switch Sb1 off (i.e., opens), thereby creating more dead time after the second negative pulse peak 310′ shown in FIG. 3.Similarly, additional positive and negative pulse peaks (eg, 308'' and 310'') and additional dead times may be generated if desired.

[0064] 1A and 1B, the generator 104 may measure tissue parameters, such as tissue impedance, to select appropriate treatment parameters, such as current and / or voltage levels. Additionally, in accordance with certain embodiments of the present technology, the generator 104 may use target current and / or target voltage control to control the level of tissue treatment.

[0065] In target current control, also called constant current control, the voltage is adjusted to treat tissue with a target current. More specifically, in target current control, the tissue impedance is measured and the voltage is selected to obtain the target current. As an example, if the target current is 30 amperes (A) and the measured tissue impedance is 100 ohms (Ω), the voltage may be adjusted to 3000 volts (V) since V=I*R=30A*100Ω=3000V. As another example, if the target current is 30 amperes (A) and the measured tissue impedance is 80 ohms (Ω), the voltage may be adjusted to 2400 volts (V) since V=I*R=30A*80Ω=2400V. As yet another example, if the target current is 30 amps (A) and the measured tissue impedance is 120 ohms (Ω), then the voltage may be adjusted to 3600 volts (V) since V=I*R=30A*120Ω=3600V. The HV voltage sense circuit 210 may be used to identify when the voltage stored in the HV capacitor 206 is at a desired level. Alternatively or additionally, the HV voltage sense circuit 212 may be used to determine if the target voltage is being delivered to the patient tissue and may be used as feedback to increase or decrease what voltage level the HV capacitor 206 should be charged to. The HV current sense circuit 214 may be used to measure the current delivered to the patient tissue through the active electrode 108 and this measurement may be used as feedback to increase or decrease what voltage level the HV capacitor 206 should be charged to. The advantage of using target current control, also known as constant current control, is that it allows the tissue treatment system to compensate for variations in the electrode array and tissue impedance when delivering PEF treatment, resulting in more consistent and predictable treatment outcomes, improving efficacy especially for patients with high tissue impedance, and improving safety by reducing the chance of overtreatment, injury, and arcing for patients with low tissue impedance.

[0066] In target voltage control, also called voltage constant control, the current is adjusted to treat tissue with a target voltage. More specifically, in target voltage control, the impedance of the tissue is measured and the current is selected to obtain the target voltage. As an example, if the target voltage is 3000V and the measured tissue impedance is 100Ω, then the current may be adjusted to 30A, since I=V / R=3000V / 100Ω=30A. As another example, if the target voltage is 3000V and the measured tissue impedance is 80 ohms (Ω), then the current may be adjusted to 37.5A, since I=V / R=3000V / 80Ω=37.5A. As yet another example, if the target voltage is 3000V and the measured tissue impedance is 120Ω, then the current may be adjusted to 25A, since I=V / R=3000V / 120Ω=25A.

[0067] As can be seen from the above description, regardless of whether the generator 104 is target current controlled or target voltage controlled, tissue impedance is measured so that tissue treatment voltage or current levels can be appropriately adjusted as needed to deliver the target current or voltage. According to certain embodiments, tissue impedance (for a particular location in a particular body cavity, such as a pulmonary vein) is measured by advancing the active electrode 108 of the instrument 102 to the desired location, delivering a relatively low voltage pulse (e.g., 100V), measuring the current using a current sense circuit (e.g., 214 in FIG. 2), and calculating the impedance using the formula R=V / I. For example, if the measured current is 0.8A, the tissue impedance can be calculated as R=100V / 0.8A=125Ω. As another example, if the measured current is 1.0A, the tissue impedance can be calculated as R=100V / 1.0A=100Ω. The reason a relatively low voltage pulse (e.g., 100V) is used to determine tissue impedance is because the voltage pulse should be below the level at which a therapeutic effect occurs. According to certain embodiments of the present technology, the voltage of the low voltage pulse used to determine tissue impedance is in the range of, but not limited to, 1V to 100V. Herein, the low voltage (LV) pulse, or more generally the LV signal, generated and used to determine tissue impedance is also referred to as the LV impedance measurement signal. In contrast, herein, the high voltage (HV) pulse, or more generally the HV signal, generated and used for treatment is also referred to as the HV tissue treatment signal, or more simply the HV treatment signal.

[0068] The LV tissue impedance measurement signal described herein includes one or more voltage pulses, each voltage pulse having a peak-to-peak voltage not exceeding 100V, more specifically, in the range of 1V to 100V. The HV tissue treatment signal described herein includes one or more voltage pulses, each voltage pulse having a peak-to-peak voltage of at least 500V, more specifically, in the range of 500V to 10,000V. In a specific embodiment, the peak-to-peak voltage of each pulse of the HV tissue treatment signal is at least 5 times greater than the peak-to-peak voltage of each pulse of the LV tissue impedance measurement signal, e.g., if the LV voltage pulse is 50V, then the HV voltage pulse is at least 500V.

[0069] 2, if output signal generator 158 is used not only to generate an HV therapy signal (e.g., in the range of 2500V-3500V), but also to generate an LV impedance measurement signal (e.g., in the range of 10V-100V) used to determine tissue impedance, then each time the output signal generator 158 is used to transition from generating an HV therapy signal to generating an LV impedance measurement signal, the voltage stored in HV capacitor 206 must be significantly decreased. Furthermore, each time the output signal generator 158 is used to transition from generating an LV impedance measurement signal to generating an HV therapy signal, the voltage stored in HV capacitor 206 must be significantly increased. This increase and decrease in the voltage stored in HV capacitor 206 can take time, which may increase the overall time it takes for a physician to perform a therapy procedure.

[0070] According to certain embodiments of the present technology, rather than relying on the same circuitry to generate both the HV therapy signal and the LV impedance measurement signal, a separate circuit is used to generate the LV impedance measurement signal from the circuitry used to generate the HV therapy signal. In such an embodiment, the same controller (e.g., FPGA or processor) may be used to control the generation of both the HV therapy signal and the LV impedance measurement signal. A high-level block diagram of such an embodiment is shown in FIG. 5A.

[0071] Referring to Figure 5A, there is shown an HV signal generator 501, an LV signal generator 502, and a controller 503 used to control the generation of the HV therapy signal and the LV impedance measurement signal by the HV signal generator 501 and the LV signal generator 502. In Figure 5A, the HV signal generator 502 is shown as including an HV power supply 202, an HV capacitor 206, and a wave shaping circuit 208, which have already been described above with reference to Figure 2 and need not be described again. In other embodiments, the HV signal generator 502 may include alternative and / or additional circuitry.

[0072] 5A, an HV voltage sense circuit 214 is used to sense the voltage between the active electrode 108 and the return electrode 140 when the HV signal generator 501 is being used and / or is about to be used to generate the HV therapy signal. An HV current sense circuit 214 is used to sense the current sent through the active electrode 108 when the HV signal generator 501 is being used and / or is about to be used to generate the HV therapy signal. Also shown in FIG. 5A is an LV voltage sense circuit 514 that is used to sense the voltage between the active electrode 108 and the return electrode 140 when the LV signal generator 503 is being used and / or is about to be used to generate the HV therapy signal. The LV current sense circuit 514 is used to sense the current sent through the active electrode 108 when the LV signal generator 503 is being used and / or is about to be used to generate the LV impedance measurement signal.

[0073] An advantage of using the HV voltage sense circuit 212 during generation of the HV therapy signal and the LV voltage sense circuit 512 during generation of the LV impedance measurement signal is that the resolution of the measurements by sense circuit 212 and the resolution of the measurements by sense circuit 512 are optimized, specifically tailored to the range of expected HV measurements and the range of expected LV measurements, respectively. In contrast, if the voltage sense circuit that senses the voltage between the active electrode 108 and the return electrode 140 during use of the HV signal generator 501 and the voltage sense circuit that senses the voltage between the active electrode 108 and the return electrode 140 during use of the LV signal generator 502 were the same voltage sense circuit, the resolution of the HV and / or LV measurements would be reduced (i.e., not optimal).

[0074] An advantage of using the HV current sense circuit 214 during generation of the HV therapy signal and the LV current sense circuit 514 during generation of the LV impedance measurement signal is that the resolution of the measurements by sense circuit 214 and the resolution of the measurements by sense circuit 514 are specifically tailored and optimized for the range of expected HV current measurements and the range of expected LV current measurements, respectively. In contrast, if the current sense circuit that senses the current delivered to the active electrodes 108 during use of the HV signal generator 501 and the current sense circuit that senses the current delivered to the active electrodes 108 during use of the LV signal generator 502 were the same current sense circuit, the resolution of the HV current measurements and / or the LV current measurements would be reduced (i.e., not optimal).

[0075] FIG. 5B shows exemplary details of how the LV signal generator 502 can be implemented similarly to the HV signal generator 501. Referring to FIG. 5B, in this example, the LV signal generator 502 is shown as including an LV power supply 504, an LV capacitor 506, and a wave shaping circuit 508. The LV power supply 504 is configured to selectively provide a low voltage DC signal used to charge the LV capacitor 206 to a desired voltage level. In certain embodiments, a voltage sense circuit 510 may be used to determine when the LV capacitor 506 has been charged to the desired voltage level, but this is not required. The LV power supply 504 may include, for example, an AC / DC converter that takes an AC line and outputs a DC signal. The LV power supply 504 may also include a step-up or step-down voltage regulator that receives the output of the AC / DC converter, converts the output of the AC / DC converter to the desired voltage level, and maintains the voltage level at the desired level. The LV power supply 504 may include additional and / or alternative circuitry as would be understood by one skilled in the art. The switch Sp2 is used to selectively connect the LV power supply 504 to the LV capacitor 506. Instead of (or in addition to) using the switch Sp2 to control whether the LV power supply 504 charges the LV capacitor 506, the output of the LV power supply 504 may be selectively enabled and disabled by the controller 503, thereby selectively controlling whether the LV capacitor 506 is charged by the LV power supply 504 at any given time. Thus, if the output of the LV power supply 504 is selectively enabled and disabled by the controller 503, optionally, the switch Sp2 may not be present. In FIG. 5B, a LV waveform shaping circuit 508 similar to the waveform shaping circuit 208 described above may be used to generate a pulsed or square wave LV impedance measurement signal.

[0076] 5B, in an alternative embodiment, the LV capacitor 506 may be omitted altogether if the LV power supply 504 outputs a voltage large enough that energy does not need to be stored in a capacitor to generate the LV impedance measurement signal. Note that the wave shaping circuit 508 may be different than shown, for example, if the LV impedance measurement signal has a sinusoidal or other shaped waveform. Thus, embodiments of the present technology are not limited to the specific wave shaping circuits 508 and 208 shown and described herein. For example, if the LV impedance measurement signal is a sinusoid, the LV wave shaping circuit may be implemented using an oscillator such as, but not limited to, a Wien bridge oscillator or a Colpitts crystal oscillator.

[0077] The bleed resistor 507 is used to selectively discharge all or a portion of the energy stored by the LV capacitor 506 by selectively turning on (i.e., closing) the switch S_bleed2. For example, when the controller 503 determines using the LV voltage sense circuit 510 that the voltage stored by the LV capacitor 506 exceeds a desired level, the controller 503 may turn on (i.e., close) the switch S_bleed2 until the voltage stored by the LV capacitor 506 is reduced to the desired level, at which point the controller 503 may turn off (i.e., open) the switch S_bleed2. Each of the switches Sp2 and S_bleed2 may be implemented using, but is not limited to, an insulated gate bipolar transistor (IGBT), another type of transistor, or a relay. The bleed resistor 507 may be implemented using a string of resistors connected in series and / or in parallel with each other, depending on the particular implementation. It is also possible to not use a bleed resistor and instead dump the excess voltage stored by the LV capacitor 506 into the patient tissue.

[0078] FIG. 5C shows an exemplary detail of how the LV signal generator 502 can be realized according to another embodiment, where the same wave-shaping circuit 208 is used jointly by both the HV signal generator 501 and the LV signal generator 502. In the embodiment of FIG. 5C, there is a switch Sv controlled by the controller 503 to either connect the HV power supply 202 (and / or the HV capacitor 206) to the wave-shaping circuit 208 or connect the LV power supply 504 (and / or the LV capacitor 506) to the wave-shaping circuit 208. While the switch Sv connects the HV power supply 202 (and / or the HV capacitor 206) to the wave-shaping circuit 208, the wave-shaping circuit 208 is part of the HV signal generator 501. While the switch Sv connects the LV power supply 504 (and / or the LV capacitor 506) to the wave-shaping circuit 208, the wave-shaping circuit 208 is part of the LV signal generator 502. 5C, in one embodiment, the LV capacitor 506 may be omitted altogether if the LV power supply 504 outputs a voltage large enough that no energy needs to be stored in a capacitor to generate the LV impedance measurement signal. Note that the wave shaping circuit 208 used jointly by both generators 501, 502 may be different than shown and still be within the scope of the embodiments described herein.

[0079] 5D shows an exemplary detail of how the LV signal generator 502 can be realized according to yet another embodiment. In the embodiment shown in FIG. 5D, when the Sp switch is closed and / or the HV power supply 202 is enabled, the Sv1 switch is closed, and the Sv2 switch is opened, the HV power supply not only charges one or more HV capacitors 206, but also charges one or more LV capacitors 506. Since the capacitance of the LV capacitor 506 is much smaller than the capacitance of the HV capacitor 206 (e.g., less than one-fifth of the capacitance of the HV capacitor 206), the magnitude of the voltage stored in the LV capacitor 506 is much smaller than the magnitude of the voltage stored in the HV capacitor 206 and the LV capacitor 506 collectively (e.g., less than one-fifth of the voltage stored in the HV capacitor 206 and the LV capacitor 506 collectively). In the embodiment of Fig. 5D, when switch Sv1 is closed and switch Sv2 is open, the charge stored collectively in HV capacitor 206 and LV capacitor 506 is provided to waveform shaping circuit 208 and used to generate the HV therapy signal. When switch Sv is open and switch Sv2 is closed, only the charge stored in LV capacitor 506 is provided to waveform shaping circuit 208 and used to generate the LV impedance measurement signal. In this way, HV power supply 202 is used jointly by both HV signal generator 501 and LV signal generator 502. Other variations are possible and are within the scope of the embodiments described herein. For example, a single-pole, double-throw switch may be used instead of the two single-pole, single-throw switches Sv1 and Sv2, in which case when the single-pole, double-throw switch is in a first position, the voltages collectively stored in the HV capacitor 206 and the LV capacitor 506 are supplied to the waveform shaping circuit 208 and used to generate the HV therapy signal, and when the single-pole, double-throw switch is in a second position, only the voltage stored in the LV capacitor is supplied to the waveform shaping circuit 208 and used to generate the LV impedance measurement signal.

[0080] More generally, in the embodiment of FIG. 5D , the controller 503 may control various switches such that a first subset of the capacitors 206, 506 are connected to the waveform shaping circuit 208 during a first time period when the LV tissue impedance measurement signal is to be delivered to the patient tissue via the electrodes 108, 140, and a second subset of the capacitors 206, 506 are connected to the waveform shaping circuit 208 during a second time period when the HV tissue treatment signal is to be delivered to the patient tissue via the electrodes 108, 140. In such an embodiment, the voltage of the HV tissue treatment signal is at least five times greater than the voltage of the LV tissue impedance measurement signal. Further, in such an embodiment, the first subset of capacitors includes at least one of the plurality of capacitors 206, 506, and the second subset of capacitors includes at least one of the plurality of capacitors and is different from the first subset. 5D, bleed resistor 207 may be used to selectively discharge all or a portion of the energy stored by capacitors 206, 506 by selectively turning on (i.e., closing) switch S_bleed. It is also possible to eliminate the bleed resistor and instead bleed the excess voltage stored by capacitors 206 and 506 into the patient tissue.

[0081] 5A, 5B, 5C, and 5D, the HV voltage sense circuit 212 is used to sense the voltage between the active electrode 108 and the return electrode 140 when the HV signal generator 501 is being used and / or is about to be used to generate the HV therapy signal, and the LV voltage sense circuit 512 is used to sense the voltage between the active electrode 108 and the return electrode 140 when the LV signal generator 503 is being used and / or is about to be used to generate the HV therapy signal. An advantage of using the HV voltage sense circuit 212 during generation of the HV therapy signal and the LV voltage sense circuit 512 during generation of the LV impedance measurement signal is that the resolution of the measurements by the sense circuit 212 and the resolution of the measurements by the sense circuit 512, respectively, can be adjusted and optimized, particularly to the range of expected HV measurements and the range of expected LV measurements. In alternative embodiments, the same voltage sense circuit may be used regardless of whether the HV therapy signal or the LV impedance measurement signal is being generated. However, such alternative embodiments may result in reduced (ie, less than optimal) resolution of the HV and / or LV voltage measurements.

[0082] 5A, 5B, 5C, and 5D, the HV current sense circuit 214 is used when the HV therapy signal is being generated, and the LV current sense circuit 514 is used when the LV impedance measurement signal is being generated. An advantage of using the HV current sense circuit 214 during generation of the HV therapy signal and the LV current sense circuit 514 during generation of the LV impedance measurement signal is that the resolution of the measurements by the sense circuit 214 and the resolution of the measurements by the sense circuit 514, respectively, can be tailored and optimized, particularly to the range of expected HV current measurements and the range of expected LV current measurements. In an alternative embodiment, the same current sense circuit is used to sense the current supplied to the active electrodes 108 during use of the HV signal generator 501 and to sense the current supplied to the active electrodes 108 during use of the LV signal generator 502. However, in such an alternative embodiment, the resolution of the HV current measurements and / or the LV current measurements will be reduced (i.e., not optimal).

[0083] In Figures 5A, 5B, 5C, and 5D, the output signal generating circuit 158 ​​may include additional circuitry not shown, as will be appreciated by those skilled in the art. For example, a step-up transformer, a filter, and / or a DC blocking capacitor may be optionally connected between the output nodes (denoted as OUT1 and OUT2) of the wave shaping circuit 208 and the active electrode 108 and the return electrode 140. The step-up transformer may be used to step-up the voltage signal generated between the output nodes (OUT1 and OUT2) of the wave shaping circuit 208 to a desired level and to isolate the HV power supply 202 and the wave shaping circuit 208 from the electrodes 108, 140. The filter may be, for example, an RC snubber circuit including a resistor and a capacitor connected in series between the electrodes 108 and 140, which may be used to remove high frequency transients or ringing that may occur due to the leakage inductance of the transformer. The DC blocking capacitor may be used to prevent low frequency and direct current from inadvertently flowing through the patient tissue.

[0084] In certain embodiments, the LV current sense circuit 514 measures the current delivered to the patient tissue via the active electrodes 108 while the LV tissue impedance measurement signal (generated using the LV signal generator 502) is delivered to the patient tissue, and the HV current sense circuit 214 measures the current delivered to the patient tissue via the active electrodes 108 while the HV tissue treatment measurement signal (generated using the HV signal generator 501) is delivered to the patient tissue. In such embodiments, the controller 503 may determine an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the current measured by the LV current sense circuit 514. Additionally, the controller 503 may set the voltage of the HV tissue treatment signal (generated using the HV signal generator 501) based on the estimate of the impedance of the patient tissue, and may adjust the voltage of the HV tissue treatment signal (generated using the HV signal generator 501) based on the current measured by the HV current sense circuit 214.

[0085] The terms high voltage (HV) and low voltage (LV) as used herein are relative terms, with a voltage considered to be HV being at least 5 times greater than a voltage considered to be LV. In specific embodiments, the LV signal has a voltage of 100V or less and the HV signal has a voltage of at least 5 times that of the LV signal. In certain embodiments, the HV signal has a magnitude of at least 1000V. More generally, the LV signals described herein are used to measure the impedance of patient tissue as opposed to being used to treat (e.g., ablate) tissue, and therefore are often referred to herein as LV tissue impedance measurement signals. In contrast, the HV signals described herein are used to treat (e.g., ablate) tissue, and therefore are often referred to herein as HV tissue treatment signals, or more simply, HV treatment signals.

[0086] In each of the embodiments described above with reference to Figures 5A-5D, the output signal generator 158 of the signal generator 104 introduced in Figures 1A and 1B is shown to include both an HV signal generator 501 and an LV signal generator 502, as well as a controller 503. In such embodiments, the LV signal generator 502 is used to generate an LV tissue impedance measurement signal, and the HV signal generator 501 is used to generate an HV tissue treatment signal having a voltage at least 5 times greater than the voltage of the LV tissue impedance measurement signal. The controller 503 controls the timing of delivery of the HV tissue treatment signal (generated with the HV signal generator 501) and the LV tissue impedance measurement signal (generated with the LV signal generator 502) to the patient tissue via the active electrode 108 and the return electrode 140. As can be understood from the above description of Figures 5A-5D, the controller 503 can control the generation and delivery of signals by controlling various switches shown in Figures 5A-5D and / or by controlling the timing of enabling or disabling of various components (e.g., power supplies).

[0087] In certain embodiments, the LV current sense circuit 514 measures the current delivered to the patient tissue via the active electrode 108 while an LV tissue impedance measurement signal, generated using the LV signal generator 502, is delivered to the patient tissue. In certain such embodiments, the controller 503 determines an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal (generated using the LV power supply 504) delivered to the patient tissue and based on the current measured by the LV current sense circuit 514, and controls the voltage of the HV tissue treatment signal (generated using the HV signal generator 501) based on the estimate of the patient tissue impedance.

[0088] In certain embodiments, the controller 503 controls the voltage of the HV tissue treatment signal (generated using the HV signal generator 501) based on an estimate of the impedance of the patient tissue so that when the HV tissue treatment signal is delivered to the patient tissue, the patient tissue is treated with a current approximately equal to a predetermined target current. The predetermined target current may be a default target current whose value is stored in a memory or register of the generator 104 or may be specified by a clinician using the user interface 150 of the generator 104.

[0089] In certain embodiments, between separate instances of generating an HV tissue treatment signal delivered to the patient tissue using HV signal generator 501, controller 503 causes LV tissue impedance measurement signal to be delivered to the patient tissue using LV signal generator 502. Controller 503 determines an updated estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on an updated measurement of the current delivered to the patient tissue, measured using LV current sense circuit 514. Controller 503 then adjusts the voltage of the HV tissue treatment signal generated using HV signal generator 501 if the updated estimate of the impedance of the patient tissue differs from the previous estimate of the impedance of the patient tissue. In this way, the next time the HV tissue treatment signal is delivered to the patient tissue, the patient tissue is treated with a current approximately equal to the predetermined target current.

[0090] Methods according to certain embodiments of the present technology will now be described using the high level flow diagram shown in FIG. 6. These methods are for use with an output signal generator (e.g., 158) of a signal generator (e.g., 104), which includes both an HV signal generator (e.g., 501) and an LV signal generator (e.g., 502). With reference to FIG. 6, step 602 includes placing an active electrode of a therapeutic energy delivery device, such as a catheter, in contact with patient tissue at the site to be treated. An example of such an active electrode is the electrode 108 of the device (e.g., catheter) 102 shown in FIG. 1A and described above with reference to FIG. 1A. Step 602 or another step may include attaching a return electrode, e.g., 140, externally to the patient's skin. The return electrode, e.g., 140, may alternatively be an implanted electrode, e.g., but not limited to, located on the catheter or sheath.

[0091] Continuing to refer to FIG. 6, step 604 includes generating an LV tissue impedance measurement signal and transmitting the LV tissue impedance measurement signal to the patient tissue via the active and return electrodes. The LV tissue impedance measurement signal generated in step 604 may be generated using a signal generator, such as 104, and more specifically using its output signal generator 158. An example of output signal generator 158 is shown in FIGs. 5A-5D and described above with reference to FIGs. 5A-5D. As described in greater detail above, in step 602, the LV tissue impedance measurement signal may be transmitted to the patient tissue using a therapeutic energy delivery instrument, such as 102.

[0092] Step 606 includes measuring the current delivered to the patient tissue via an active electrode, for example 108, while an LV tissue impedance measurement signal is delivered to the patient tissue. Step 606 may be performed, at least in part, using a current sense circuit, such as circuit 514 or 214 described above, but is not limited to such.

[0093] Step 608 includes determining an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the measured current. Step 608 may be performed, at least in part, by a controller, such as controller 203 or 503 described above. For example, if the LV tissue impedance measurement signal delivered in step 604 was a 100V pulse and the current measured in step 606 was 0.8 amps, then R=100V / 0.8A=125Ω, and the estimate determined in step 608 may be 125Ω. As another example, if the measured current was 1.0A, then the tissue impedance may be calculated as R=100V / 1.0A=100Ω.

[0094] Step 610 includes generating an HV tissue treatment signal and delivering the HV tissue treatment signal via the active and return electrodes. As discussed above, the voltage of the HV tissue treatment signal is at least 5 times greater than the voltage of the LV tissue impedance measurement signal. As further discussed above, generating the HV treatment signal includes controlling the voltage of the HV tissue treatment signal based on an estimate of the impedance of the patient tissue. For example, if target current control, also referred to as constant current control, is used, step 610 may include adjusting the voltage to treat the tissue with the target current. As an example, if the target current is 30A and the estimated tissue impedance is 100Ω, then V=I*R=30A*100Ω=3000V, so the voltage may be adjusted to be 3000V. As another example, if the target current is 30A and the estimated tissue impedance is 80Ω, then V=I*R=30A*80Ω=2400V, so the voltage may be adjusted to be 2400V. As yet another example, if the target current is 30A and the estimated tissue impedance is 120Ω, then V=I*R=30A*120Ω=3600V, and so the voltage may be adjusted to 3600V. The HV voltage sense circuit 210 may be used to identify when the voltage stored on the HV capacitor 206 is at a desired level. Alternatively or additionally, the HV voltage sense circuit 212 may be used to determine if the target voltage is being delivered to the patient tissue and may be used as feedback for what voltage level to raise or lower the charge on the HV capacitor 206 to. The HV current sense circuit 214 may be used to measure the current delivered to the patient tissue through the active electrode 108, and this measurement may be used as feedback for what voltage level to raise or lower the charge on the HV capacitor 206 to.

[0095] Continuing with reference to FIG. 6, step 612 includes determining whether treatment of the patient tissue at the site has been sufficient. Since the impedance of successfully treated tissue will be very low, in certain embodiments, step 612 may be performed by determining whether the impedance of the patient tissue has decreased by at least a predetermined amount. More specifically, after steps 604, 606, and 608 are repeated to obtain an updated estimate of the impedance of the patient tissue, a determination may be made as to whether there has been at least a predetermined decrease in the impedance of the patient tissue (e.g., at least a 50% decrease). If there has not been at least a predetermined decrease in the tissue impedance (i.e., the answer to the determination at step 612 is No), as can be seen from FIG. 6, in another instance of step 610, an additional HV tissue treatment signal is generated and delivered to the same site. More specifically, steps 604, 606, and 608 may be performed again as part of step 612, after which step 610 may be repeated to generate and deliver an additional HV tissue treatment signal (using the updated estimate of the tissue impedance determined in the most recent step 608) to the same site. If there has been at least a predetermined decrease in tissue impedance (ie, the answer to the question at step 612 is Yes), flow proceeds to step 614 .

[0096] In step 614, a determination is made as to whether there are any more patient tissue sites to be treated. If the answer to the determination in step 614 is no, the method may end. However, if the answer to the determination in step 614 is yes, the flow proceeds to step 616. In step 616, an active electrode, e.g. 108, is placed at the new site so as to be in contact with the other patient tissue to be treated. The flow then returns to step 604, as shown in FIG. 6. While the active electrode is in contact with the other patient tissue to be treated, steps 604, 606, 608, 610 and 612 are performed. This process is repeated until all tissue to be treated has actually been treated, as can be seen in FIG. 6.

[0097] As described above in the description of FIG. 3, the HV tissue treatment signal generated and delivered at each instance of step 610 may include one or more packets of pulses, which may be biphasic or monophasic. Prior to delivering the packets of pulses, tissue impedance may be measured, or more specifically estimated, at steps 604, 606, and 608, and as part of step 610, depending on whether target current control or target voltage control is used, the voltage may be adjusted to treat the tissue with a target current or the current may be adjusted to treat the tissue with a target voltage based on the measured tissue impedance. An updated estimate of the tissue impedance may then be determined to determine whether further HV tissue treatment signals should be delivered to the particular patient tissue, or that the particular patient tissue has already been sufficiently treated. In other words, before delivering the first packet of HV tissue treatment pulses and between successive packets of HV treatment pulses, tissue impedance may be estimated and used to adjust the voltage or current.

[0098] Depending on the particular implementation, step 612 may be performed following each packet of HV pulses generated and delivered at an instance of step 610. Alternatively, step 612 may be performed following a series of packets of HV pulses generated and delivered at an instance of step 610. Other variations are contemplated and are within the scope of the embodiments described herein. In any case, near real-time feedback is provided to determine whether additional treatment should be performed at a patient's tissue site, and if so, such near real-time feedback can be used to adjust the current and / or voltage of the HV tissue treatment pulses delivered at the next instance of step 610. Thus, in the embodiment summarized with reference to FIG. 6, impedance is monitored intermittently during treatment delivery to determine whether additional treatment should be performed at a site or to determine whether the active electrode has been moved to a new site. example

[0099] Example 1 1. A tissue treatment system comprising: a low voltage (LV) signal generator used to generate an LV tissue impedance measurement signal; a high voltage (HV) signal generator used to generate an HV tissue treatment signal having a voltage at least five times greater than a voltage of the LV tissue impedance measurement signal; and a controller configured to control timing of delivery of the HV tissue treatment signal generated using the HV signal generator and the LV tissue impedance measurement signal generated using the LV signal generator to patient tissue via an active electrode and a return electrode.

[0100] Example 2 The tissue treatment system of Example 1, further comprising a current sense circuit configured to measure a current delivered to the patient tissue via the active electrode while an LV tissue impedance measurement signal generated using the LV signal generator is delivered to the patient tissue, and the controller is further configured to determine an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the current measured by the current sense circuit, and to control the voltage of the HV tissue treatment signal generated using the HV signal generator based on the estimate of the impedance of the patient tissue.

[0101] Example 3 The tissue treatment system of Example 2, wherein the control device is configured to control the voltage of the HV tissue treatment signal generated using the HV signal generator based on an estimate of the impedance of the patient tissue so that when the HV tissue treatment signal is delivered to the patient tissue, the patient tissue is treated with a current approximately equal to a predetermined target current.

[0102] Example 4 4. The tissue treatment system of claim 3, wherein, between multiple separate instances of generating an HV tissue treatment signal delivered to the patient tissue using the HV signal generator, the controller is configured to: generate an LV tissue impedance measurement signal delivered to the patient tissue using the LV signal generator; determine an updated estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on an updated measurement of a current delivered to the patient tissue measured using the current sense circuit; and if the updated estimate of the impedance of the patient tissue differs from a previous estimate of the impedance of the patient tissue, adjust the voltage of the HV tissue treatment signal generated using the HV signal generator the next time the HV tissue treatment signal is delivered to the patient tissue such that the patient tissue is treated with a current approximately equal to the predetermined target current.

[0103] Example 5 5. The tissue treatment system of any one of Examples 1 to 4, wherein the LV signal generator includes an LV power supply and the HV signal generator includes an HV power supply that is different from the LV power supply of the LV signal generator.

[0104] Example 6 The tissue treatment system of Example 5, wherein the LV signal generator includes an LV waveform shaping circuit connected between the LV power supply and the active and return electrodes, and the HV signal generator includes an HV waveform shaping circuit distinct from the LV waveform shaping circuit and connected between the HV power supply and the active and return electrodes.

[0105] Example 7 The tissue treatment system of Example 5, wherein the LV signal generator and the HV signal generator share the same wave shaping circuitry.

[0106] Example 8 8. The tissue treatment system of any one of Examples 1 to 7, further comprising: an LV current sense circuit configured to measure current delivered to the patient tissue via the active electrode while an LV tissue impedance measurement signal generated using the LV signal generator is delivered to the patient tissue; and an HV current sense circuit distinct from the LV current sense circuit and configured to measure current delivered to the patient tissue via the active electrode while an HV tissue treatment signal generated using the HV signal generator is delivered to the patient tissue.

[0107] Example 9 The tissue treatment system of Example 8, wherein the controller is further configured to determine an estimate of the impedance of the patient tissue based on a voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on a current measured by the LV current sense circuit, set a voltage of the HV tissue treatment signal generated using the HV signal generator based on the estimate of the impedance of the patient tissue, and adjust a voltage of the HV tissue treatment signal generated using the HV signal generator based on the current measured by the HV current sense circuit.

[0108] Example 10 1. A tissue treatment system comprising: a pair of electrodes; a plurality of capacitors; a power source configured to charge the plurality of capacitors; a waveform shaping circuit connected between the plurality of capacitors and the pair of electrodes; and a controller configured to connect a first subset of the capacitors to the waveform shaping circuit during a first time period during which a low voltage (LV) tissue impedance measurement signal is to be sent to patient tissue via the pair of electrodes and to connect a second subset of the capacitors to the waveform shaping circuit during a second time period during which a high voltage (HV) tissue impedance measurement signal is to be sent to the patient tissue via the pair of electrodes, wherein a voltage of the HV tissue treatment signal is at least five times greater than a voltage of the LV tissue impedance measurement signal, the first subset of capacitors including at least one of the plurality of capacitors, and the second subset of capacitors including at least one of the plurality of capacitors and different from the first subset.

[0109] Example 11 The tissue treatment system of Example 10, wherein a first subset of the power supply, waveform shaping circuitry, and capacitors are components of an LV signal generator used to generate an LV tissue impedance measurement signal, and a second subset of the power supply, waveform shaping circuitry, and capacitors are components of an HV signal generator used to generate an HV tissue treatment signal, and the power supply and waveform shaping circuitry are shared by both the LV signal generator and the HV signal generator.

[0110] Example 12 The tissue treatment system of Example 10 or 11, wherein the pair of electrodes includes an active electrode and a return electrode, and the tissue treatment system further comprises a current sense circuit configured to measure a current delivered to the patient tissue via the active electrode while the LV tissue impedance measurement signal is delivered to the patient tissue, and the control device is further configured to determine an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the current measured by the current sense circuit, and to control the voltage of the HV tissue treatment signal based on the estimate of the impedance of the patient tissue.

[0111] Example 13 The tissue treatment system of Example 12, wherein the control device is configured to control the voltage of the HV tissue treatment signal based on an estimate of the impedance of the patient tissue so that when the HV tissue treatment signal is delivered to the patient tissue, the patient tissue is treated with a current approximately equal to a predetermined target current.

[0112] Example 14 The tissue treatment system of Example 13, wherein between multiple separate instances in which the HV tissue treatment signal is generated and sent to the patient tissue, the controller is configured to determine an updated estimate of the impedance of the patient tissue, and if the updated estimate of the impedance of the patient tissue differs from a previous estimate of the impedance of the patient tissue, adjust the voltage of the generated HV tissue treatment signal so that the next time the HV tissue treatment signal is sent to the patient tissue, the patient tissue is treated with a current approximately equal to the predetermined target current.

[0113] Example 15 1. A method comprising: (a) generating a low voltage (LV) tissue impedance measurement signal and transmitting the LV tissue impedance measurement signal to patient tissue via active and return electrodes; (b) measuring a current transmitted to the patient tissue via the active electrodes while the LV tissue impedance measurement signal is transmitted to the patient tissue; (c) determining an estimate of the impedance of the patient tissue based on a voltage of the LV tissue impedance measurement signal transmitted to the patient tissue and based on the measured current; and (d) generating a high voltage (HV) tissue treatment signal and transmitting the HV tissue treatment signal via the active and return electrodes, wherein a voltage of the HV tissue treatment signal is at least five times a voltage of the LV tissue impedance measurement signal, and generating the HV tissue treatment signal comprises controlling a voltage of the HV tissue treatment signal based on the estimate of the impedance of the patient tissue.

[0114] Example 16 The method of Example 15, wherein steps (a), (b), (c), and (d) are performed in this order and, after being performed in this order, are repeated in this order, wherein when step (c) is repeated, an updated estimate of the impedance of the patient tissue is obtained and when step (d) is repeated, the voltage of the HV tissue treatment signal is controlled based on the updated estimate of the impedance of the patient tissue.

[0115] Example 17 The method of Example 15, wherein steps (a), (b), (c) and (d) are performed in this order, and after being performed in this order, steps (a), (b) and (c) are repeated in this order to obtain an updated estimate of the impedance of the patient tissue, and the method further includes determining whether the treatment of the patient tissue was sufficient or, in an additional instance of step (d), determining whether additional treatment should be performed on the patient tissue based on the updated estimate of the impedance of the patient tissue.

[0116] Example 18 The method of Example 17, wherein if an additional treatment is performed on the patient tissue in an instance of the additional step (d), generating the HV treatment signal in the additional step (d) includes controlling a voltage of the HV tissue treatment signal based on an updated estimate of the impedance of the patient tissue.

[0117] Example 19 19. The method of any one of Examples 15 to 18, wherein generating the LV tissue impedance measurement signal in step (a) is performed using an LV signal generator, and generating the HV tissue treatment signal in step (c) is performed using an HV signal generator that is different from the LV signal generator.

[0118] Example 20 20. The method of any one of Examples 15 to 19, further comprising: charging a plurality of capacitors using a power source; and shaping the LV tissue impedance measurement signal and the HV tissue treatment signal using a waveform shaping circuit connected between the plurality of capacitors and the active and return electrodes, wherein generating and transmitting the LV tissue impedance measurement signal in step (a) comprises connecting a first subset of the capacitors to the waveform shaping circuit during a first time period; and generating and transmitting the HV tissue treatment signal in step (c) comprises connecting a second subset of the capacitors to the waveform shaping circuit during a second time period, wherein the first subset of capacitors comprises at least one of the plurality of capacitors and the second subset of capacitors comprises at least one of the plurality of capacitors and is different from the first subset.

[0119] It should be understood that the subject matter described herein is not limited in its application to the details of construction and arrangement of components set forth in the description herein or illustrated in the drawings. The subject matter described herein is capable of other embodiments and can be practiced or carried out in various ways. It should also be understood that the phrases and terms used herein are for purposes of explanation and should not be considered limiting. As used herein, the words "comprises," "includes," or "has," and variations thereof, are meant to encompass the items listed thereafter and equivalents, as well as additional items. Furthermore, it should be noted that the term "based on" as used herein should be construed to mean based at least in part, unless otherwise indicated, and means that there may be one or more other factors on which a determination, etc. is made. For example, if a determination is made based on the results of a comparison, the determination may be made based on one or more other factors in addition to being made based on the results of the comparison.

[0120] The embodiments of the present technology have been described above using functional building blocks illustrating the execution of certain functions and their relationships. In this specification, the boundaries of these functional building blocks have been defined for convenience of description. Other boundaries may be defined as long as the certain functions and their relationships are appropriately performed. Accordingly, any such other boundaries are within the scope and spirit of the claimed invention. For example, some of the steps shown in Figures 5A to 5D may be combined or separated, and the order of various steps may be changed. As another example, some of the boundaries of the blocks shown in Figures 1A to 2C may be changed.

[0121] It should be understood that the above description is illustrative and not restrictive. For example, the above-described embodiments (and / or aspects thereof) may be combined with each other. Furthermore, many modifications may be made to the teachings of the embodiments of the present technology to adapt to a particular situation or material without departing from the scope of the present technology. Many other embodiments will become apparent to those skilled in the art upon reading the above description. Thus, the scope of the embodiments of the present technology should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "in" are used as the plain equivalents of "comprising" and "at", respectively. Furthermore, in the following claims, terms such as "first", "second" and "third" are used merely for identification purposes and are not intended to impose numerical requirements on their subject matter. Moreover, the following claim limitations are not written in means-plus-function form, and are not intended to be construed under 35 U.S.C. §112(f) unless a claim limitation expressly uses the phrase "means for" followed by a description of a function without further structure.

Claims

1. 1. A tissue treatment system comprising: a low voltage (LV) signal generator used to generate an LV tissue impedance measurement signal; a high voltage (HV) signal generator used to generate an HV tissue treatment signal having a voltage at least five times greater than a voltage of the LV tissue impedance measurement signal; a controller configured to control the timing of delivery of the HV tissue treatment signal, generated using the HV signal generator, and the LV tissue impedance measurement signal, generated using the LV signal generator, to patient tissue via active and return electrodes; A tissue treatment system comprising:

2. a current sense circuit configured to measure a current delivered to the patient tissue via the active electrode while the LV tissue impedance measurement signal generated using the LV signal generator is delivered to the patient tissue; The control device includes: determining an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the current measured by the current sense circuit; 10. The tissue treatment system of claim 1, further configured to control the voltage of the HV tissue treatment signal generated using the HV signal generator based on the estimate of the impedance of the patient tissue.

3. 3. The tissue treatment system of claim 2, wherein the controller is configured to control the voltage of the HV tissue treatment signal generated using the HV signal generator based on the estimate of the impedance of the patient tissue such that the patient tissue is treated with a current approximately equal to a predetermined target current when the HV tissue treatment signal is delivered to the patient tissue.

4. During a plurality of separate instances in which the HV tissue treatment signal is generated using the HV signal generator and delivered to the patient tissue, the controller: using the LV signal generator to generate the LV tissue impedance measurement signal that is delivered to the patient tissue; determining an updated estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on an updated measurement of the current delivered to the patient tissue measured using the current sense circuit; 4. The tissue treatment system of claim 3, configured to adjust the voltage of the HV tissue treatment signal generated using the HV signal generator when the updated estimate of the impedance of the patient tissue differs from a previous estimate of the impedance of the patient tissue, such that the patient tissue is treated with a current approximately equal to the predetermined target current the next time the HV tissue treatment signal is delivered to the patient tissue.

5. the LV signal generator includes an LV power supply; 5. The tissue treatment system of claim 1, wherein the HV signal generator includes an HV power supply that is distinct from the LV power supply of the LV signal generator.

6. the LV signal generator includes an LV waveform shaping circuit connected between the LV power supply and the active electrode and the return electrode; 6. The tissue treatment system of claim 5, wherein the HV signal generator includes an HV waveform shaping circuit distinct from the LV waveform shaping circuit and connected between the HV power supply and the active electrode and the return electrode.

7. The tissue treatment system of claim 5 , wherein the LV signal generator and the HV signal generator share the same wave shaping circuitry.

8. an LV current sense circuit configured to measure a current delivered to the patient tissue via the active electrode while the LV tissue impedance measurement signal, generated using the LV signal generator, is delivered to the patient tissue; 8. The tissue treatment system of claim 1, further comprising an HV current sense circuit distinct from the LV current sense circuit and configured to measure current delivered to the patient tissue via the active electrode while the HV tissue treatment signal generated using the HV signal generator is delivered to the patient tissue.

9. The control device includes: determining an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the current measured by the LV current sense circuit; setting a voltage of the HV tissue treatment signal generated using the HV signal generator based on the estimate of the impedance of the patient tissue; 10. The tissue treatment system of claim 8, further configured to adjust the voltage of the HV tissue treatment signal generated using the HV signal generator based on the current measured by the HV current sense circuit.

10. 1. A tissue treatment system comprising: A pair of electrodes; A plurality of capacitors; a power source configured to charge the plurality of capacitors; a waveform shaping circuit connected between the plurality of capacitors and the pair of electrodes; A control device, The control device includes: connecting a first subset of the capacitors to the wave shaping circuit during a first time period during which a low voltage (LV) tissue impedance measurement signal is to be delivered to patient tissue via the pair of electrodes; configured to connect a second subset of the capacitors to the wave shaping circuit during a second time period during which a high voltage (HV) tissue treatment signal is to be delivered to the patient tissue via the pair of electrodes; a voltage of the HV tissue treatment signal is at least 5 times greater than a voltage of the LV tissue impedance measurement signal; the first subset of capacitors includes at least one of the plurality of capacitors; the second subset of capacitors includes at least one of the plurality of capacitors and is different from the first subset; Tissue treatment system.

11. the power supply, the wave shaping circuit, and the first subset of capacitors are components of an LV signal generator used to generate the LV tissue impedance measurement signal; the power supply, the wave shaping circuit, and the second subset of capacitors are components of an HV signal generator used to generate the HV tissue treatment signal; The tissue treatment system of claim 10 , wherein the power supply and the wave shaping circuitry are shared by both the LV signal generator and the HV signal generator.

12. The pair of electrodes includes an active electrode and a return electrode, the tissue treatment system further comprising a current sense circuit configured to measure a current delivered to the patient tissue through the active electrode while the LV tissue impedance measurement signal is delivered to the patient tissue; The control device includes: determining an estimate of the impedance of the patient tissue based on the voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the current measured by the current sense circuit; The tissue treatment system of claim 10 or 11, further configured to control the voltage of the HV tissue treatment signal based on the estimate of the impedance of the patient tissue.

13. 13. The tissue treatment system of claim 12, wherein the controller is configured to control the voltage of the HV tissue treatment signal based on the estimate of the impedance of the patient tissue so that, when the HV tissue treatment signal is delivered to the patient tissue, the patient tissue is treated with a current approximately equal to a predetermined target current.

14. Among multiple separate instances in which the HV tissue treatment signal is generated and delivered to the patient tissue, the controller: determining an updated estimate of the impedance of the patient tissue; 14. The tissue treatment system of claim 13, configured to adjust the voltage of the generated HV tissue treatment signal when the updated estimate of the impedance of the patient tissue differs from a previous estimate of the impedance of the patient tissue, such that the patient tissue is treated with a current approximately equal to the predetermined target current the next time the HV tissue treatment signal is delivered to the patient tissue.

15. 1. A method comprising: (a) generating a low voltage (LV) tissue impedance measurement signal and transmitting the LV tissue impedance measurement signal to patient tissue via an active electrode and a return electrode; (b) measuring a current delivered to the patient tissue via the active electrode while the LV tissue impedance measurement signal is delivered to the patient tissue; (c) determining an estimate of the impedance of the patient tissue based on a voltage of the LV tissue impedance measurement signal delivered to the patient tissue and based on the measured current; (d) generating a high voltage (HV) tissue treatment signal and delivering the HV tissue treatment signal through the active electrode and the return electrode; a voltage of the HV tissue treatment signal is at least 5 times the voltage of the LV tissue impedance measurement signal; The method, wherein generating the HV tissue treatment signal includes controlling the voltage of the HV tissue treatment signal based on the estimate of the impedance of the patient tissue.

16. 16. The method of claim 15, wherein steps (a), (b), (c), and (d) are performed in that order and then repeated in that order, wherein when step (c) is repeated an updated estimate of the impedance of the patient tissue is determined and when step (d) is repeated the voltage of the HV tissue treatment signal is controlled based on the updated estimate of the impedance of the patient tissue.

17. steps (a), (b), (c) and (d) are performed in that order, after which steps (a), (b) and (c) are repeated in that order to obtain an updated estimate of the impedance of the patient tissue; 16. The method of claim 15, further comprising: determining whether treatment of the patient tissue was sufficient or whether additional treatment should be performed on the patient tissue, in an instance of a further step (d), based on the updated estimate of the impedance of the patient tissue.

18. 20. The method of claim 17, wherein if an additional treatment is performed on the patient tissue in an instance of additional step (d), generating the HV tissue treatment signal in the additional step (d) includes controlling the voltage of the HV tissue treatment signal based on the updated estimate of the impedance of the patient tissue.

19. generating the LV tissue impedance measurement signal in step (a) is performed using an LV signal generator; 19. The method of any one of claims 15 to 18, wherein generating the HV tissue treatment signal in step (c) is performed using an HV signal generator different from the LV signal generator.

20. Charging a plurality of capacitors using a power source; shaping the LV tissue impedance measurement signal and the HV tissue treatment signal using a wave shaping circuit connected between the plurality of capacitors and the active and return electrodes; generating and transmitting the LV tissue impedance measurement signal in step (a) includes connecting a first subset of the capacitors to the wave shaping circuit during a first time period; generating and delivering the HV tissue treatment signal in step (c) includes connecting a second subset of the capacitors to the wave shaping circuit during a second time period; the first subset of capacitors includes at least one of the plurality of capacitors; 20. The method of claim 15, wherein the second subset of capacitors includes at least one of the plurality of capacitors and is different from the first subset.

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