A contact mass system and method

Abstract

A system includes an ablation generator configured to provide ablation energy to a body via a catheter, and a contact quality monitor configured to provide a quality signal indicative of a contact quality associated with one or more surface body electrodes. The contact quality monitor provides an interrogation signal to the electrodes and receives a sense signal. The contact quality monitor provides the quality signal indicative of a low contact quality in response to the sense signal.

Description

[0001] Cross-references to related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 150,818, filed February 18, 2021, the entire contents of which are incorporated herein by reference. Background Technology

[0003] This disclosure relates to systems and methods for monitoring the contact quality of return electrodes (such as body surface electrodes) during an ablation procedure.

[0004] Various therapies are used to treat a wide range of conditions affecting human anatomy. For example, arrhythmias are sometimes treated with ablation therapy. Damage is created in tissue when it is ablated, or at least subjected to ablation energy generated by an ablation generator and delivered by an ablation catheter. Electrodes mounted on or within the ablation catheter are used to create tissue necrosis in the heart tissue to correct conditions such as atrial arrhythmias (including, but not limited to, ectopic atrial tachycardia, atrial fibrillation, and atrial flutter). Arrhythmias (i.e., irregular heart rhythms) can lead to a variety of dangerous conditions, including loss of synchronous atrioventricular contraction and blood flow stagnation, which can result in various illnesses and even death. The primary cause of atrial arrhythmias is believed to be stray electrical signals within the left or right atrium of the heart. The ablation catheter applies ablation energy (such as radiofrequency (RF) energy, cryoablation, laser, chemicals, high-intensity focused ultrasound, etc.) to the heart tissue to create damage. This damage disrupts unwanted electrical pathways, thereby limiting or preventing stray electrical signals that lead to arrhythmias.

[0005] An RF ablation system comprises an RF source and a return electrode. The RF source is typically a small electrode on the tip of a catheter, while the return electrode can be one or more return electrodes (e.g., adhesive surface patches) positioned on the body and electrically coupled to a neutral or grounded return node. This one or more return electrodes can be attached to the skin of the body using adhesives or other fastening techniques and have a larger surface area than the small electrode on the tip of the catheter. A decrease in contact quality occurs if the return electrode loses adhesion to the skin or body during the procedure. Summary of the Invention

[0006] Some embodiments relate to a system for monitoring the contact quality of a first body surface electrode. The system includes a generator configured to provide ablation energy, an electronic control unit (ECU) configured to be electrically connected to the first body surface electrode and the generator, and circuitry connecting the first body surface electrode to the ECU. The ECU is configured to send an interrogation signal to the first body surface electrode via the circuitry and to receive a sensing signal in response to the interrogation signal via the circuitry. The ECU determines the contact quality of the first body surface electrode by processing the sensing signal.

[0007] In some embodiments, the interrogation signal is provided at a first frequency if ablation energy is being provided, and at a second frequency if ablation energy is not being provided. In some embodiments, the first body surface electrode includes a first conductive portion and a second conductive portion, wherein the first conductive portion and the second conductive portion are separated by a gap. The interrogation signal may be provided across the gap, and the sensing signal may have a voltage corresponding to the impedance across the gap.

[0008] Some embodiments relate to a system including a second body surface electrode and a variable impedance circuit coupled in series with at least one of a first and second body surface electrodes. The system further includes: a first current sensor configured to sense a first current level associated with ablation energy provided by a generator through the first body surface electrode; and a second current sensor configured to sense a second current level associated with ablation energy provided by the generator through the second body surface electrode. The circuit is coupled to the first and second current sensors. The circuit provides a control signal to the variable impedance circuit to balance the first current level through the first body surface electrode and the second current level through the second body surface electrode.

[0009] In some embodiments, the first frequency is lower than the second frequency, the first frequency being between 10 kHz and 20 kHz, and the second frequency being between 20 kHz and 200 kHz. In some embodiments, the circuit provides the sensing signal in response to a first relationship between the sensing signal and a threshold, and dynamically adjusts the threshold in response to a current level associated with the ablation energy provided by the generator through the first body surface electrode.

[0010] Some embodiments relate to a method for determining the contact quality of a first body surface electrode attached to a body. The method includes providing an interrogation signal to the first body surface electrode. The interrogation signal is provided at a frequency. This frequency is determined in response to whether ablation energy is provided to the body. The method also includes receiving a sensing signal from the first body surface electrode in response to the interrogation signal, and processing the sensing signal to determine the contact quality.

[0011] In some embodiments, a method may balance the currents passing through first and second body surface electrodes. The method includes sensing a first current level associated with ablation energy passing through the first body surface electrode, sensing a second current level associated with ablation energy provided through the second body surface electrode, and balancing the currents passing through the first and second body surface electrodes in response to the first and second current levels. Attached Figure Description

[0012] This disclosure will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, wherein like reference numerals refer to like elements, wherein:

[0013] Figure 1 This is a schematic diagram of a system for navigating and operating a medical device within the body, according to some embodiments;

[0014] Figure 2 According to some embodiments Figure 1 A general block diagram of the electronic control unit (ECU) of the system shown;

[0015] Figure 3 It is coupled to two return electrodes according to some embodiments. Figure 2 The diagram shown is a general block diagram of a contact quality monitor.

[0016] Figure 4 According to some embodiments Figure 3 A more detailed block diagram of the contact quality monitor is shown; and

[0017] Figure 5 This illustrates some embodiments. Figure 1 A flowchart illustrating an exemplary operation of the system is shown. Detailed Implementation

[0018] This disclosure relates to a dynamically configurable contact quality monitoring system and method. The invention also relates to a contact quality monitoring or control system and method that actively balances currents via two or more return electrodes. In some embodiments, the system and method are configured to adjust the frequency of interrogation signals provided to the return electrodes to improve contact quality measurement and avoid interference. In some embodiments, a higher frequency interrogation signal is used during non-treatment (e.g., non-ablation) periods to obtain more reliable, consistent readings of contact quality. In some embodiments, a lower frequency interrogation signal is used during treatment (e.g., ablation) periods to obtain frequency separation, avoid interference, and provide continuous monitoring during treatment. Advantageously, according to some embodiments, the contact quality system and method of some embodiments do not solely rely on comparing the sensed signal from the interrogation signal to a fixed threshold to determine low contact quality of the return electrode (e.g., a 30-40% reduction in adhesive patch area).

[0019] According to some embodiments, the contact quality system and method use an instantaneous R current level via one or more return electrodes to issue a contact quality alarm or trip. Advantageously, the contact quality system and method monitor the respective current levels through two or more return electrodes and / or actively balance the current between the return electrodes. Details of various examples of this disclosure will now be described with specific reference to the accompanying drawings.

[0020] Reference Figure 1 An example of a system 100 for navigating and manipulating a medical device within body 112 includes a catheter 102, such as an ablation catheter, schematically shown entering a heart (e.g., tissue 116) that has been separated from body 112. In some embodiments, catheter 102 may be derived from a TactiCath contact force ablation catheter. TM Families, such as TactiCath TM Contact ablation catheter, Sensor Enabled from Abbott Laboratories TM However, it should be understood that system 100 can detect applications associated with various medical devices used within body 112 for diagnosis or treatment. Furthermore, it should be understood that system 100 can be used to navigate medical devices for diagnosis or treatment of parts of body 112 other than tissue 116 (e.g., heart tissue). Further description of the system and components is contained in U.S. Patent Application Serial No. 13 / 839,963, filed March 15, 2013, now U.S. Patent No. 9,693,820, the entire contents of which are incorporated herein by reference as if fully set forth herein.

[0021] The catheter 102 may include a handle 124, a cable connector or interface 126 located proximal to the handle 124, and a shaft 104 (also referred to herein as a catheter shaft). The shaft 104 may include a proximal end 130 and a distal end 132. A tip portion 106 may be located at the distal end 132. The handle 124 provides a physician with a means of holding the catheter 102 in place and may also provide tools for manipulating or guiding the shaft 104 within the body 112. For example, the handle 124 may include tools for changing the length of one or more drawstrings extending from the handle 124 through the catheter 102 to the distal end 132 of the shaft 104. The construction of the handle 124 may vary.

[0022] The shaft 104 may be made of a conventional material such as polyurethane and may define one or more lumens configured to receive and / or transport an electrical conductor 156, fluid, or surgical instrument. The shaft 104 may be introduced into a blood vessel or other structure within the body 112 using a conventional guide. The shaft 104 may then be manipulated or guided through the body 112 to a desired location, such as tissue 116, using a lead or drawstring or other tools known in the art, including remotely guided systems. The shaft 104 may also allow the transport, delivery, and / or removal of fluids (including flushing fluids and bodily fluids), medications, and / or surgical instruments or devices. It should be noted that any number of methods may be used to introduce the shaft 104 into the area within the body 112. This may include guides, sheaths, guiding sheaths, guiding members, guide lines, or other similar devices. For ease of discussion, the term "guide" will be used herein.

[0023] In some examples, system 100 may include a positioning system, a display 140, and an electronic control unit (ECU) 142. ECU 142 may include, but is not limited to, a central processing unit (CPU), a graphics processing unit (GPU), a microprocessor, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complementary metal-oxide-semiconductor (CMOS), etc. In some examples, the ECU may include memory, such as random access memory (RAM), read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), dynamic random access memory (DRAM), static random access memory (SRAM), flash memory, etc. In some embodiments, ECU 142 is processor-based circuitry.

[0024] In some embodiments, the positioning system is a hybrid system based on electric field (impedance-based) and magnetic field, comprising an electric field-based positioning system 136 and a magnetic field-based positioning system 138. For example, the positioning system could be Abbott's Ensite Precision. TM A cardiac mapping system. A positioning system is provided to determine the location and orientation of similar devices within catheter 102, tip portion 106, and body 112. For example, the location or orientation of tip portion 106 may be based on a reference or position of one or more electrodes (e.g., positioning electrode 134) of tip portion 106. In some examples, positioning electrode 134 may include, for example... Figure 1The example shows a ring electrode. The operating principle of system 136 is that when a low-amplitude electrical signal passes through the thoracic cavity, body 112 acts as a voltage divider (or potentiometer or rheostat) so that the potential or field strength measured at one or more electrodes (e.g., positioning electrode 134) on catheter 102 can be used to determine the position of catheter 102 relative to a pair of external patch electrodes by using Ohm's law and the relative position of a reference electrode (e.g., in the coronary sinus).

[0025] exist Figure 1 In the illustrated configuration, the electric field-based positioning system 136 also includes three pairs of body surface electrodes 144. In some embodiments, the three pairs of body surface electrodes 144 are patch electrodes provided to generate electrical signals for determining the position of the catheter 102 within a three-dimensional coordinate system 146. The body surface electrodes 144 can also be used to generate electrophysiological (EP) data (e.g., electrophysiological signals) about the tissue 116. To create an axis-specific electric field within the body 112, the body surface electrodes 144 are placed on opposing surfaces of the body 112 (e.g., the chest and back, the left and right sides of the thoracic cavity, and the neck and legs), forming generally orthogonal X, Y, and Z axes. A reference electrode is typically placed near the stomach to provide a reference value and serves as the origin of the coordinate system 146 of the navigation system.

[0026] According to such Figure 1 The exemplary electric field-based positioning system 136 shown includes a body surface electrode 144 with a right-side patch 144. X1 Left side patch 144 X2 Neck patch 144 Y1 Leg patch 144 Y2 144 chest patches Z1 and back patch 144 Z2 Each body surface electrode 144 is connected to a switch 148 (e.g., a multiplexer) and a signal generator 150. Body surface electrode 144 X1 144 X2 Placed along the first (X) axis; body surface electrode 144 Y1 144 Y2 Placed along the second (Y) axis, and body surface electrodes 144 Z1 144 Z2 Positioned along the third (Z) axis. A sinusoidal current is driven through each pair of body surface electrodes 144, and voltage measurements are obtained for one or more position sensors (e.g., positioning electrodes 134) associated with the conduit 102. The measured voltage is a function of the distance of the position sensor from the patch electrode. The measured voltage is compared with the potential at a reference electrode, and the position of the position sensor within the coordinate system 146 of the navigation system is determined.

[0027] In some embodiments, the body surface electrode 144 includes at least one return electrode 144r for providing a return path to the return node 147 of the ablation generator 122 during an ablation procedure. In some embodiments, the body surface electrode 144 is manufactured by Ensite from Abbott Laboratories. TM NavX TM A surface electrode kit is provided. In some embodiments, the return electrode 144r is one or more large surface area patches disposed on the lower back of the body 112. In some embodiments, one or more of the aforementioned body surface electrodes 144 may be configured to serve as return electrodes 144r for an ablation procedure. Exemplary structures and uses of patch electrodes or body surface electrodes are discussed in U.S. Patent Application Publication No. 2017 / 0100055, which is incorporated herein by reference.

[0028] In some embodiments, ECU 142 includes a contact quality monitor 149. In some embodiments, ECU 142 is integrated into ablation generator 122. In some embodiments, contact quality monitor 149 may be a standalone unit, part of switch 148, or other component of system 100. Contact quality monitor 149 may be part of or integrated with one or more of generator 122, switch 148, and ECU 142. Contact quality monitor 149 sends an interrogation signal through return electrode 144r and processes sensing signals associated with the interrogation signal to determine the impedance of return electrode 144r through the skin / body, thereby determining contact quality. If, in some embodiments, the contact quality is insufficient, contact quality monitor 149 provides a warning to system 100 and automatically trips to cut off the supply of ablation energy. In some embodiments, contact quality monitor 149 continuously measures the current through each of the plurality of return electrodes 144r and adjusts the series impedance of each return path to actively balance the current through return electrode 144r. The operation of contact quality monitor 149 will be referenced below. Figure 2-5 A more detailed description is provided, and it can be used with any type of return electrode.

[0029] In this example, the magnetic field-based positioning system 138 uses a magnetic field to detect the position and orientation of the catheter 102 within the body 112. In such a system, a magnetic field generator 152 with three orthogonally arranged coils (not shown) can be used to generate a magnetic field within the body 112, and the strength, direction, and frequency of the magnetic field can be controlled. The magnetic field generator 152 can be located above or below the patient (e.g., below the scanning table) or at another suitable location. The magnetic field is generated by the coils, and current or voltage measurements are obtained from one or more position sensors associated with the catheter 102. The measured current or voltage is proportional to the distance of the sensor from the coil, thus allowing the determination of the sensor's position within the coordinate system 154 of the system 138.

[0030] As the conduit 102 moves within the body 112 and within the electric field generated by the electric field-based positioning system 136, the voltage reading from the positioning electrode 134 changes, thereby indicating the position of the conduit 102 in the electric field and in the coordinate system 146 established by the system 136. The positioning electrode 134 may be adapted to transmit a position signal to the ECU 142.

[0031] The catheter 102 may be configured to deliver therapy and geometric modeling or electrophysiological mapping. In some examples, the catheter 102 may include at least one electrode 108 configured to detect electrophysiological signals from tissue 116 or to provide energy for ablation of tissue 116. In one example, the at least one electrode 108 may be communicatively coupled to an ablation generator 122 for delivering electrical signals suitable for providing ablation energy to the at least one electrode 108. In some embodiments, the ablation generator 122 may be an Ampere from Abbott Laboratories. TMThe generator provides a sinusoidal electrical signal at 485 kHz. Other types, frequencies, and forms of RF signals can be provided from the ablation generator 122. In some embodiments, at least one electrode 108 is an electrode assembly that can be used for a variety of diagnostic and therapeutic purposes, including, but not limited to, cardiac mapping and / or ablation (e.g., RF ablation or irreversible electroporation (IRE ablation) / pulsed field ablation (PFA)). The ablation generator 122 can be configured for bipolar PFA, which uses high-voltage and short-duration bipolar and biphasic pulse trains to generate tissue alterations without significant heating. For example, the electrode assembly can be configured for use in bipolar-based electroporation therapy. Specifically, a pair of electrodes are electrically coupled to an IRE generator (e.g., the ablation generator 122 configured as an IRE generator) and configured to be selectively excited with opposite polarities to generate a potential and corresponding electric field therebetween for IRE therapy. That is, one electrode is configured to act as a cathode, while the other electrode is configured to act as an anode. In some embodiments, at least one electrode 108 may be configured as a monopolar electrode assembly and uses a patch electrode (as a return electrode or neutral electrode) (e.g., return electrode 144r). The electrode can provide ablation energy for IRE treatment by delivering a current as a pulsed electric field (i.e., PFA), the pulsed electric field being in the form of ultrashort pulses (2-5 microsecond (μs) pulse width and 20-40 μs pulse period) grouped into pulse trains of 100-1000 pulses. In some embodiments, monopolar IRE ablation energy is provided at a voltage of 2.5 kV, resulting in a peak pulse current as high as 100 A.

[0032] In some examples, conduit 102 may optionally be connected to a fluid source 118 for delivering a biocompatible flushing fluid (e.g., saline) via pump 120. Pump 120 may include a fixed-rate roller pump or a variable-capacity syringe pump with a gravity supply source from fluid source 118. Connector or interface 126 provides mechanical, fluid, and electrical connections for tubing or cables extending from pump 120 and ablation generator 122. Conduit 102 may also include other conventional components not shown herein, such as temperature sensors, additional electrodes, and corresponding conductors or leads. In some embodiments, tip portion 106 includes a tip electrode associated with a grid conduit or basket conduit.

[0033] ECU 142 provides means for operating various components of system 100, including catheter 102, ablation generator 122, and magnetic field generator 152 of magnetic field-based positioning system 138. ECU 142 may also provide means for determining the electrophysiological properties (e.g., signals) of tissue 116, the position and orientation of catheter 102 relative to tissue 116 and body 112, controlling ablation of tissue 116, or any combination thereof. ECU 142 also provides means for generating display signals for controlling display 140.

[0034] Display 140 is provided to convey information to a physician to aid in diagnosis and treatment. Display 140 may include one or more conventional computer monitors or other display devices. Display 140 may present a graphical user interface (GUI) to the physician. The GUI may include various information, including, for example: contact quality information, warnings or alarms, images of the geometry of tissue 116, electrophysiological data associated with tissue 116 (e.g., mapping of signals from electrode 108), graphs showing the voltage levels of various positioning electrodes 134 over time, and images of catheter 102 and other medical devices, as well as information indicating the position of catheter 102 and other devices relative to tissue 116.

[0035] Reference Figure 2 ECU 142 includes a contact quality monitor 149 and a trip circuit 232. ECU 142 is coupled to a display 140 and an ablation generator 122. The contact quality monitor 149 is coupled to one or more body surface electrodes 144 to provide treatment to body 112 (e.g., a human or animal). In some embodiments, at least one return electrode 144r is provided in the return path from body 112 to return node 147 of ablation generator 122.

[0036] In some embodiments, the return electrode 144r may be a single return electrode implemented as a patch. The return electrode 144r may be two or more return electrodes, and in some embodiments, the return electrodes are implemented as two or more patches. In some embodiments, the return electrode 144r may be of various shapes, such as square, rectangular, circular, trapezoidal, etc. In some embodiments, the return electrode 144r includes conductive portions electrically separated by a slit or gap as described below, such that contact quality can be determined based on the impedance associated with the slit. The return electrode 144r may be an adhesive conductive structure applied to the skin of the lower back or other parts of the body 112. The return electrode 144r may be a surface body electrode as described in U.S. Patent Application Publication No. 2017 / 0100055, which is incorporated herein by reference, and provides good electrical contact with the skin of the patient's body 112. Various conductive materials and layers may be used in the return electrode 144r, such as silver-carbon films, metal films, conductive adhesives or gels, conductive foam sponge materials, barrier layers, etc. Other methods of transferring electrical energy can also be implemented, such as capacitive coupling of conductive elements to the patient's skin.

[0037] The contact quality monitor 149 is also coupled to the current transformer 258 and the variable impedance circuit 268. In some embodiments, the contact quality monitor 149 is a monitor or control circuit that performs at least one of the following operations: 1) providing an interrogation signal at a first frequency in the range of 20 kHz to 200 kHz during a first time period when ablation is not performed, and providing an interrogation signal at a second frequency in the range of 10 kHz to 20 kHz during a second time period when ablation is performed; and 2) providing a signal indicating low contact quality in response to a sensing signal relating to a threshold value set in response to the current level used during ablation.

[0038] In some embodiments, the contact quality monitor 149 is a circuit (e.g., processor-based circuitry) including a conductor or lead 252 that provides an interrogation signal to the return electrode 144r. In some embodiments, the return electrode 144r is a single patch having a gap or slit 202 that electrically separates the conductive medium of the return electrode 144r. The interrogation signal is provided at the conductor, lead, or output 252 and passes through the slit 202 through the contact between the skin and the return electrode 144r. The conductor, lead, or input 254 provides a sensing signal from the return electrode 144r to the contact quality monitor 149. The output 252 and input 254 provide interfaces for providing and receiving the interrogation signal and the sensing signal, and may include more than one conductor. The sensing signal is derived from the interrogation signal and represents the impedance across the slit 202 and subsequent contact quality. In some embodiments, the interrogation signal is a constant current signal provided across the slit 202, and the sensing signal is a voltage measurement across the slit 202 representing the impedance across the slit 202. The sensed signal is compared to a threshold to determine whether the contact quality is sufficient for the procedure. In some embodiments, the contact quality monitor 149 provides a quality signal to the trip circuit 232 and other parts of the ECU 142. In some examples, the ECU 142 may provide an alarm, warning, or other contact information for display on the display 140 in response to the quality signal.

[0039] When a quality signal indicates insufficient contact quality (e.g., a 30-40% reduction in the area of ​​the adhered patch), trip circuit 232 shuts down, disables, or prevents ablation generator 122 from providing ablation energy. In some embodiments, trip circuit 232 includes a switch that isolates ablation generator 122 from body 112. In some embodiments, trip circuit 232 is part of contact quality monitor 149 and provides an interruption or flag to ECU 142 in the event of insufficient contact quality.

[0040] In some embodiments, during ablation, an interrogation signal is provided in a lower frequency range (e.g., 10-20 kHz) to avoid interference with higher frequency signals from the ablation generator 122. In some embodiments, this frequency separation also allows for a low-impedance path for returning energy to the return node 147 and a higher-impedance path for the interrogation signal, for standard electronic components. Additionally, the capacitive component of the impedance of body 112 is more pronounced at lower frequencies, which can lead to additional inconsistencies in contact quality measurements. Therefore, when ablation is not performed, an interrogation signal is provided at a higher frequency in a higher frequency range (e.g., 20-200 kHz) to provide more consistent and accurate measurements of impedance and contact quality.

[0041] By making the total surface mount current I patch Divided by the adhesive patch area A effective(Assuming a uniform current distribution across the effective patch area) to obtain the current concentration I con (I con =I patch / A effective Therefore, if the patch current is low, a lower minimum adhesion area is required for the appropriate current concentration.

[0042] In some embodiments, a quality signal indicates insufficient contact quality when the impedance is higher than a threshold representing the impedance associated with insufficient contact quality. In some embodiments, this threshold is not a fixed threshold but is adjusted based on the current level or power level received at return node 147. The threshold is lowered when the current level is high because, in some embodiments, a higher level of contact quality (lower impedance) may be required during higher current ablation procedures. In some embodiments, a lower level of contact quality is tolerable during lower current procedures. In some embodiments, contact quality monitor 149 uses an algorithm to continuously adjust the threshold for contact quality (adhesive patch area) based on the amount of current passing through return electrode 144r.

[0043] Current transformer 258 provides a power sensing signal or current level signal to contact quality monitor 149 via lead 256. In some embodiments, current transformer 258 may be any device for sensing power or current in a conductor associated with return node 147. In some embodiments, the peak current level used during the procedure may be used to adjust the threshold. In some embodiments, a peak current level over a period of time is used. In some embodiments, a real-time current level is used to adjust the threshold. In some embodiments, the current level is provided by ECU 142 based on system configuration or user input. In some embodiments, the threshold is also adjusted based on whether a higher frequency interrogation signal is provided when ablation is not performed or whether a lower frequency interrogation signal is provided when ablation is performed (e.g., for each specific threshold of the higher and lower frequency interrogation signals). In some embodiments, the magnitude of the threshold is inversely proportional to the current level associated with the ablation energy provided by ablation generator 122 via return electrode 144r.

[0044] In some embodiments, the threshold represents a threshold impedance for low contact quality. In some embodiments, the sensing signal is a voltage signal representing impedance (e.g., the higher the sensing signal, the higher the impedance). A low contact quality signal is provided when the sensing signal is above the threshold. The low contact quality signal can be used to provide a warning or trip to system 10. Conversely, a signal representing sufficient contact quality can be provided when the sensing signal is below the threshold. The threshold can be selected or adjusted for a specific type of return electrode 144r, the number of return electrodes 144r, the location of the return electrodes 144r on body 112, or the type of program. The specific type of return electrode 144r, the number of return electrodes 144r, and the location of the return electrodes 144r can be sensed or input by the user as data.

[0045] In some embodiments, the threshold is fixed and represents the current concentration. Actual current concentration I con Compared with a threshold, where the actual current concentration I con It is achieved by using a sensing signal (represented as A) effective ) and the current level (I) from the current transformer 258 patch ) to calculate (I con =I patch / A effective Using current concentration I con Dynamic thresholds are advantageous because they reduce the number of cases where output is inappropriately suppressed.

[0046] A contact quality signal is also provided to the ECU 142 for an audible or visual warning of low contact quality. In some embodiments, a warning may be provided based on a threshold. Even if the threshold is not reached, a warning or alert may be provided if the impedance change becomes higher. In some embodiments, a rapidly increasing impedance may indicate that adjustment of the return electrode 144r may be necessary. The display 140 may also provide an analog indication of contact quality based on the contact quality signal or a sensing signal.

[0047] In some embodiments, the contact quality monitor 149 adjusts the impedance of the impedance circuit 268 between the return electrode 144r and the return node 147. The impedance circuit 268 includes one or more active devices, resistors, capacitors, or inductors for adjusting the impedance via a switching path, active control, or other control techniques.

[0048] ECU 142 and contact quality monitor 149 are implemented as circuits comprising one or more of a general-purpose processor, a special-purpose processor, a memory, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a processing unit group, an interface, isolation and filtering components, analog and digital support circuitry, or other suitable electronic processing components. The memory is one or more storage devices (e.g., RAM, ROM, flash memory, hard disk storage) for storing data and computer code to perform and facilitate the various processes, layers, and modules described herein. The memory may be or include volatile or non-volatile memory and may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures of the inventive concepts disclosed herein. The memory is communicatively connected to a processor and includes computer code or instruction modules for performing one or more processes described herein. The memory includes various circuits, software engines, and / or modules that enable one or more processors to perform the systems and methods described herein.

[0049] Reference Figure 3 Contact quality monitor 149 is coupled to return electrode 144r ( Figure 2 The return electrode 144r is implemented as two or more return electrodes 270a and 270b. Any number of return electrodes 144r can be used with the contact quality monitor 149, wherein each return electrode 144r is associated with a channel for corresponding interrogation signals, sensing signals, sensing current levels, impedance adjustment, etc. The return electrodes 270a and 270b are placed asymmetrically on the body. This arrangement can result in the return electrode 144r being positioned from the tip portion 106. Figure 1 The current flows through one of the return electrodes 270a and 270b above the other through a lower impedance path in the body. Due to this lower impedance path, one of the return electrodes 270a and 270b can receive more return energy than the other. This creates an imbalance, where one of the return electrodes 270a and 270b carries a greater current than the other. This can be undesirable in high-current modes where a uniform distribution of return current is required.

[0050] Return electrode 270a includes two conductive portions 274a and 274b, separated by a gap or slit 272a. Return electrode 270b includes two conductive portions 276a and 276b, separated by a gap or slit 272b. Lead 252a is coupled to portion 274a, and lead 252b is coupled to portion 274b. Lead 252c is coupled to portion 276a, and lead 252d is coupled to portion 276b. Sensing input 254a is coupled to portion 274a, and sensing input 254b is coupled to portion 274b. Sensing input 254c is coupled to portion 276a, and sensing input 254d is coupled to portion 276b. Leads 252a-b are the signal and return nodes for the interrogation signal of return electrode 270a, and leads 252c-d are the signal and return nodes for the interrogation signal of return electrode 270b. Sensing inputs 254a-b are used to return the sensing signal of electrode 270a, while sensing inputs 254c-d are used to return the sensing signal of electrode 270b.

[0051] The sensed signals at sensing inputs 254a and 254b are compared with a threshold to determine the contact quality of return electrode 270a. The threshold is dynamically adjusted based on the current level sensed by current transformer 258a. The sensed signals at sensing inputs 254c and 254d are compared with a threshold to determine the contact quality of return electrode 270b. In some embodiments, the sensed signals at inputs 254a-b and 254c-d are voltage measurements of an interrogation signal across gap 272a-b. The threshold is dynamically adjusted based on the current level sensed by current transformer 258b. A contact quality signal can be provided for each return electrode 270a and 270b, as well as a composite contact quality signal for both return electrodes 270a and 270b.

[0052] In some embodiments, the return paths of return electrodes 270a and 270b include corresponding impedance circuits 268a and 268b coupled to corresponding portions 274a-b and 276a-b. Impedance circuits 268a and 268b can be adjusted to balance the return current between return electrodes 270a and 270b. Leads 266a-b provide an interface to a contact quality monitor 149 and can be used to control the impedance in impedance circuits 268a-b in response to current level signals from current transformers 258a and 258b, which indicate the current in return electrodes 270a and 270b. If return electrode 270a receives more return current than return electrode 270b, the impedance of impedance circuit 268a in the return path of return electrode 270a can be increased, or the impedance of impedance circuit 268b in the return path of electrode 270b can be decreased to balance the return current between return electrodes 270a and 270b.

[0053] Current transformers 258a and 258b provide current level signals indicating the current in each return path via leads 256a-b. Leads 256a and 256b provide an interface to contact quality monitor 149. Comparison of the current levels sensed by current transformers 258a-b is used to determine the amount of impedance adjustment. Advantageously, each return electrode 270a and 270b is connected to return node 147 via impedance circuit 268a-b. Figure 1 Impedance circuits 268a-b are coupled to sections 274a-b and 276a-b, respectively, and provide a corresponding single conductor 280a-b to return node 147 via each current transformer 258a-b. Figure 1 In some embodiments, impedance circuits 268a-b are printed circuit boards (PCBs) with adjustable LC (inductor-capacitor) resonant notch filters and variable resistors R. In some embodiments, for components that cannot be adjusted by digital control, a relay array is used to switch components connected in the return path to adjust the impedance. In some embodiments, return electrodes 270a and 270b can be any number of electrodes, including three, four, or more, each associated with a path or channel having a corresponding impedance circuit, a current sensor, and an interface for sensing and interrogating signals.

[0054] Reference Figure 4 In some embodiments, the contact quality monitor 149 includes an isolated power supply circuit 302, a power converter 304, a dynamic digital control circuit 306, an isolator 308, an adjustable frequency current source 310, an analog-to-digital converter 312, an analog front-end circuit 314, and an isolation circuit 316. In some embodiments, the contact quality monitor 149 is coupled to return electrodes 270a and 270b. The dynamic digital control circuit 306 is a processor or other circuit configured to provide the operations described herein with respect to contact quality monitoring and control. The analog-to-digital converter 312 provides the dynamic digital control circuit 306 with digital data representing sensing signals from inputs 254a-d and current level signals from current transformers 258a-b.

[0055] Impedance circuits 268a and 268b are coupled in the return paths of return electrodes 270a and 270b, respectively. Advantageously, each return electrode 270a and 270b is connected to return node 147 via a corresponding impedance circuit 268a-b. In some embodiments, dynamic digital control circuit 306 controls impedance circuits 268a-b via digital control signals on leads 266a-b. Dynamic digital control circuit 306 provides signals on leads 266a-b for load balancing in response to current level sensing signals provided via leads 256a-b and analog-to-digital converter 312. Analog front-end circuitry 314 provides frequency conversion, filtering, conditioning, and other interface functions before the sensing signals are converted into digital data.

[0056] Depending on whether ablation energy is provided (e.g., in some embodiments, whether the return node 147 is receiving data from the ablation generator 122), Figure 1 The dynamic digital control circuit 306 provides interrogation signals at different frequencies based on the signal associated with the current (of the ECU 142). In some embodiments, the dynamic digital control circuit 306 receives interrogation signals from the ECU 142 (of the ECU 142). Figure 1 The interrogation signal or data indicates that ablation energy is provided so that an appropriate frequency can be selected for the interrogation signal. The frequency can be selected based on the frequency of the ablation electrical signal to avoid interference, harmonic frequencies, etc. The ability to select a frequency for the interrogation signal that does not interfere with other devices or components within system 100 is advantageous. For example, a positioning or mapping system can provide hundreds of impedance measurement signals with frequencies between 8-9 kHz and 16-22 kHz, and can provide an interrogation signal outside these frequency bands to avoid interference.

[0057] In some embodiments, the interrogation signal is provided via an AC coupling circuit such as isolation circuit 316. In some embodiments, an adjustable frequency current source 310 is digitally controlled and drives the interrogation signal across return electrodes 270a and 270b or a single patch electrode. The adjustable frequency current source 310 is a constant current source, and in some embodiments, the interrogation signal is provided with a current between 10 and 100 microamps (µA) root mean square (RMS). The resulting voltage across return electrodes 270a and 270b is provided as a sensing signal to analog-to-digital converter 312 via inputs 254a-d through analog front-end circuitry 314 for reception by dynamic digital control circuitry 306. In some embodiments, analog front-end circuitry 314 is tuned to achieve appropriate performance across all available frequencies (approximately 10 kHz to 100 kHz).

[0058] In some embodiments, the power converter 304 is a buck regulator. In some embodiments, the dynamic digital controller is a processor-based circuit, a field-programmable gate array, an application-specific circuit (ASIC), a microcontroller, or a combination thereof. An isolation barrier provides high impedance isolation from return electrodes 270a and 270b and return node 147. In some embodiments, the isolation circuit 316 is a transformer-based circuit.

[0059] Although Figure 4 The example shows two return electrodes 270a and 270b, but by adding a channel for each additional return electrode, the contact quality monitor 149 can be configured for more than two return electrodes 270a and 270b. In some embodiments, by removing the channel associated with return electrode 270b, the contact quality monitor 149 can be configured for a single return electrode 270a.

[0060] Reference Figure 1 and 5 In some embodiments, system 100 and contact quality monitor 149 operate according to process 400. In some embodiments, during operation 402, system 100 is in a non-ablation mode where no ablation energy is supplied to body 112. The non-ablation mode may include a silent mode in which the ablation generator 122 is energized or partially de-energized, and system 100 does not supply ablation energy. In some embodiments, the ablation generator 122 may provide a low-amplitude signal (e.g., at 485 kHz) for measurement purposes in the non-ablation mode.

[0061] In operation 404, contact quality monitor 149 provides an interrogation signal at a first frequency. In some embodiments, the first frequency is in the frequency range between 20 kHz and 200 kHz. Higher frequency interrogation signals provide more accurate impedance readings and can be used during non-ablation mode because there are no higher frequency, higher amplitude ablation signals, thus not interfering with the higher frequency interrogation signal. In some embodiments, the first frequency has an upper limit of approximately 100 kHz to avoid interference with signals from ablation generator 122. In some embodiments, the first frequency is a signal higher than 100 kHz or higher than 200 kHz and is selected to avoid interference with signals from ablation generator 122 (e.g., measurement signals such as 485 kHz measurement signals). In some embodiments, the first frequency is provided at a frequency between 20 and 200 kHz, selected to obtain accurate and stable patch impedance readings. The first frequency can be selected based on system parameters and design criteria, such as avoiding interference from other signals and electrical characteristics in system 100 (e.g., return electrode 144r). Figure 1 Signal interference from the capacitors, inductors, and resistors of filters, etc.

[0062] In operation 406, the contact quality monitor 149 receives a sensing signal and compares the sensing signal to a threshold to determine the contact quality. The contact quality is used to provide an alarm or trip operation for system 100. The threshold may represent impedance and can be adjusted to be lower depending on the amount of ablation energy delivered during ablation treatment (e.g., a lower threshold for a higher amount of ablation energy).

[0063] In operation 408, if the ablation mode is not entered, the contact quality monitor 149 returns to operation 404. In some embodiments, the ablation mode is a cycle in which ablation energy is delivered to the body 112. Entry into the ablation mode can be determined based on signals from the ECU 142, user input, or the presence of current associated with the ablation energy at the return electrode 144r.

[0064] If ablation mode is entered, contact quality monitor 149 proceeds to operation 412. In operation 412, contact quality monitor 149 provides an interrogation signal at a second frequency lower than the first frequency. In some embodiments, the second frequency is between 5-50 kHz (e.g., 10-20 kHz). In some embodiments, the second frequency is 12 kHz. When the interrogation signal frequency is closer to the frequency of the ablation signal provided by ablation generator 122 (e.g., 485 kHz), more noise or interference exists. In some embodiments, the second frequency is at least tens of orders of magnitude lower than the frequency of the ablation signal (e.g., approximately 50 kHz upper limit when the frequency of the ablation signal is approximately 500 kHz), thereby effectively filtering out RF noise. The second frequency is high enough that the impedance measurement values ​​are not inconsistent due to the capacitive effects of the body / patch / skin present in the measurement. The lower limit frequency of the second frequency may depend on the return electrode 144r ( Figure 1 ) and the characteristics of body 112.

[0065] In operation 412, the contact quality monitor 149 measures the current level associated with the ablation energy and adjusts a threshold based on the current level. In operation 422, the contact quality monitor 149 performs active balancing of the body surface electrode impedance in response to the current level through the return electrode 144r (e.g., measured in operation 414). Operation 422 is used if two or more return electrodes 144r are used in system 100. In some embodiments, operation 422 is optional.

[0066] Following operation 414 or 422, in operation 416, the contact quality monitor 149 receives a sensing signal and compares it to a threshold to determine the contact quality. As described above, the threshold can be dynamically adjusted. After operation 416 and in operation 418, if system 100 has not left the ablation mode, the contact quality monitor 149 returns to operation 404. If entering a non-ablation mode, the contact quality monitor 149 proceeds to operation 404. Operations 414 and 412 can be performed concurrently with other operations in process 400. After operations 406 and 416, if the contact quality is insufficient, the ablation operation can be stopped.

[0067] While embodiments of RF ablation therapy have been described above, RF ablation therapy is not disclosed in a limiting manner. For example, the contact quality monitor 149 can be used with IRE ablation therapy without departing from the scope of the claims. For example, a monopolar IRE system having two or more return electrodes 144r can use the current balancing technique of the contact quality monitor 149. In another example, a monopolar IRE system used with one or more return electrodes 144r can use the dynamic thresholding technique of the contact quality monitor 149. Furthermore, without departing from the scope of the claims, the contact quality monitor 149 can be used with other treatments and procedures using one or more return electrodes 144r. While embodiments of cardiac treatment have been described above, the contact quality monitor 149 can be used with systems designed for treating other organs. While embodiments of catheter ablation therapy have been described above, the contact quality monitor 149 can be used with non-catheter ablation systems.

[0068] It should be understood that embodiments of the methods according to the inventive concept disclosed herein may include one or more steps described herein. Furthermore, such steps may be performed in any desired order, and two or more steps may be performed simultaneously with each other. Two or more steps disclosed herein may be combined in a single step, and in some embodiments, one or more steps may be performed as two or more sub-steps. In addition, other steps or sub-steps may be performed besides or as an alternative to one or more steps disclosed herein. Although processors and non-transient computer media are disclosed, the circuitry for performing the operations may take other forms.

[0069] As can be clearly seen from the above description, the inventive concept disclosed herein is well-suited for achieving the aforementioned objectives and obtaining the advantages mentioned herein, as well as the inherent advantages of the inventive concept disclosed herein. While presently preferred embodiments of the inventive concept disclosed herein have been described for the purposes of this disclosure, it will be understood that many variations can be made that will be readily apparent to those skilled in the art, and that these variations are made within the broad scope and coverage of the inventive concept disclosed and claimed herein.

Claims

1. A system for monitoring the contact quality of a first body surface electrode, the system comprising: The generator is configured to provide ablation energy; An electronic control unit (ECU) is configured to be electrically connected to the first body surface electrode and the generator; Connect the first body surface electrode to the circuit of the ECU; The ECU is configured to send an interrogation signal to the first body surface electrode via the circuit, and to receive a sensing signal in response to the interrogation signal via the circuit. The ECU determines the contact quality of the first body surface electrode by processing the sensing signal. Wherein, when the sensing signal is higher than a threshold, the circuit provides a low contact quality signal; and The circuit is configured to dynamically adjust the threshold in response to a current level associated with the ablation energy provided by the generator through the first body surface electrode.

2. The system according to claim 1, wherein, If the ablation energy is being provided, the interrogation signal is provided at a first frequency; if the ablation energy is not being provided, the interrogation signal is provided at a second frequency.

3. The system according to claim 2, wherein, The first frequency is lower than the second frequency.

4. The system according to claim 2, wherein, The first frequency is between 10 kHz and 20 kHz, and the second frequency is between 20 kHz and 100 kHz.

5. The system according to claim 1, wherein, The first body surface electrode includes a first conductive portion and a second conductive portion, wherein the first conductive portion and the second conductive portion are separated by a gap, wherein an interrogation signal is transmitted across the gap, and the sensing signal has a voltage corresponding to the impedance across the gap.

6. The system according to claim 5, wherein, When the sensed signal is above a threshold, the circuit provides a low contact quality signal.

7. The system of claim 6 further includes a trip circuit configured to shut down, disable, or prevent the generator from providing the ablation energy in response to the low contact quality signal.

8. The system of claim 1, further comprising a second body surface electrode, wherein, Both the first body surface electrode and the second body surface electrode include a first conductive portion and a second conductive portion, with each first conductive portion separated from each second conductive portion by a corresponding gap.

9. The system according to claim 8, wherein, The circuit provides a corresponding interrogation signal to each first conductive part and each second conductive part, and receives a corresponding sensing signal from each first conductive part and each second conductive part.

10. The system according to claim 9, wherein, If the generator is providing the ablation energy, the circuit provides each of the interrogation signals at a first frequency; if the generator is not providing the ablation energy, the circuit provides each of the interrogation signals at a second frequency, the first frequency being lower than the second frequency.

11. The system according to claim 10, wherein, The circuit provides a low contact quality signal in response to at least one of the corresponding sensing signals being above a threshold.

12. The system according to claim 11, wherein, The low contact quality signal indicates that the adhesion area is reduced by more than 40% compared to the expected adhesion area of ​​the first body surface electrode or the second body surface electrode.

13. The system according to claim 1, further comprising: Second body surface electrode; A variable impedance circuit coupled in series with at least one of the first body surface electrode and the second body surface electrode; A first current sensor is configured to sense a first current level associated with the ablation energy provided by the generator through the first body surface electrode; A second current sensor is configured to sense a second current level associated with the ablation energy provided by the generator through the second body surface electrode; as well as The circuit is coupled to the first current sensor and the second current sensor, wherein the circuit provides a control signal to the variable impedance circuit to balance the first current level through the first body surface electrode and the second current level through the second body surface electrode.

14. The system according to claim 1, wherein, The circuit includes an adjustable frequency current source for providing the interrogation signal.

15. The system according to claim 1, wherein, The threshold is lowered as the current level associated with the ablation energy provided by the generator through the first body surface electrode increases.

16. The system according to claim 1, wherein, The circuit includes a current transformer disposed between the return node of the generator and the first body surface electrode, wherein the current level is determined using a current signal from the current transformer.

17. The system according to claim 1, wherein, The circuit includes an analog-to-digital converter for receiving the sensed signal.

18. The system according to claim 1, wherein, The circuit includes an adjustable impedance circuit connected in series with the first body surface electrode and the return node of the generator.

19. The system according to claim 18, wherein, The adjustable impedance circuit is tuned to block signals in a first frequency range while allowing signals in a second frequency range to pass through.

20. The system according to claim 1, further comprising: The catheter is configured to deliver ablation energy to the body; wherein the first body surface electrode is a return electrode.

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