Method and system for determining intracardiac impedance

Abstract

A method for determining the impedance of multiple electrodes in a medical device includes applying a first drive signal between first adjacent electrode pairs in the multiple electrodes and applying a second drive signal between second adjacent electrode pairs in the multiple electrodes. Since the electrode pairs overlap, the first and second adjacent electrode pairs include a common electrode. The method further includes applying an additional drive signal between additional adjacent electrode pairs and measuring the impedance of each of the adjacent electrode pairs. The measured impedance can be used not only to determine the contact state or tissue proximity but also to detect a defective electrode or defective circuit in the multiple electrodes.

Description

[Technical Field]

[0001] (Claiming priority) This application claims priority to U.S. Provisional Patent Application No. 63 / 460,471, filed on 19 April 2023, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention generally relates to catheters, as well as methods and systems for determining intracardiac impedance between electrodes on a catheter. [Background technology]

[0003] Catheters are used in many procedures within the human body, including the heart. In many of these applications, whether collecting data from surrounding tissue or performing treatment, it is crucial to determine whether a part of the catheter, particularly the electrode collecting data or performing treatment, is in contact with adjacent tissue. Many methods are used to determine tissue proximity, such as monitoring electrocardiogram signals (e.g., the voltage measured between electrodes) and / or electrode impedance. For example, the impedance between an intracardiac electrode and tissue can be determined based on the impedance measured between the intracardiac electrode and a surface patch electrode. When the intracardiac electrode is in the blood pool (i.e., not in contact with tissue), the measured impedance will be low because the conductivity of the blood pool is relatively higher than that of the tissue. Conversely, when the intracardiac electrode is in contact with tissue, the measured impedance will be high because the conductivity of the tissue is relatively lower than that of the blood pool.

[0004] However, the impedance between the intracardiac electrode and the surface patch electrode can be affected by the attributes of the surface patch electrode (i.e., the size of the surface patch electrode, the brand / type of the surface patch electrode) and the placement of the surface patch electrode on the patient's body (i.e., the conductivity of the patch and skin, and the variability of tissue conductivity). These are some of the factors that complicate the determination of tissue proximity based on measured impedance.

[0005] Developing methods and systems for more accurately measuring electrode impedance to determine tissue proximity would be beneficial. [Overview of the Initiative]

[0006] According to one embodiment, a method for measuring the impedance of multiple electrodes on a medical device comprises: applying a first drive signal between a first electrode and a second electrode to measure a first impedance value between the first electrode and the second electrode; applying a second drive signal between a second electrode and a third electrode to measure a second impedance value between the second electrode and the third electrode; and applying a third drive signal between a third electrode and a fourth electrode to measure a third impedance value between the third electrode and the fourth electrode. Each of the first, second, and third drive signals can be applied by separate signal generators.

[0007] In another embodiment, a method for detecting a defective electrode or circuit in a medical device having a plurality of electrodes at the distal end of the medical device may include applying a first drive signal between first adjacent electrode pairs in the plurality of electrodes and applying a second drive signal between second adjacent electrode pairs in the plurality of electrodes, wherein the first and second adjacent electrode pairs include a common electrode. The method further includes applying an additional drive signal between additional adjacent electrode pairs, measuring the impedance of each pair of adjacent electrodes, and using the measured impedance to detect a defective electrode or circuit in the plurality of electrodes.

[0008] In another embodiment, a system for use with a medical device configured to be inserted into a patient and having multiple electrodes at the distal end of the medical device includes multiple measurement circuits, each measurement circuit configured to apply a drive signal to a pair of electrodes among the multiple electrodes and to measure the response of the pair of electrodes associated with the drive signal. The system further includes an electronic control unit (ECU) configured to generate an impedance value for each pair of electrodes based on the measured response. One or more electrodes among the multiple electrodes may be part of two measurement circuits such that adjacent measurement circuits have a common electrode. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of a system including a medical device for insertion into a patient, which, according to several embodiments, is configured to utilize the impedance between electrodes to determine the contact state of one or more electrodes located at the distal end of the medical device.

[0010] [Figure 2] This is a schematic diagram of the distal end of a medical device having multiple splines according to several embodiments, where each spline includes multiple electrodes arranged in a basket-like array.

[0011] [Figure 3] Schematic diagrams of components used to measure the impedance between electrode pairs placed on a medical device, according to several embodiments.

[0012] [Figure 4] Schematic diagrams of components in a medical system used to process impedance measurements, according to several embodiments.

[0013] [Figure 5] A flowchart illustrating steps used to measure the impedance of each electrode pairing for multiple electrodes on a medical device, according to several embodiments.

[0014] [Figure 6] A flowchart illustrating steps used to detect a defective electrode or circuit in a medical device having multiple electrodes on the medical device, according to several embodiments.

[0015] [Figure 7] A flowchart illustrating a method, according to several embodiments, for using measured impedance values ​​to detect a defective electrode or circuit. [Modes for carrying out the invention]

[0016] According to several embodiments, the claimed invention facilitates the measurement of impedance between overlapping catheter electrode pairs without requiring an external patch or surface electrode attached to the patient's skin (i.e., a patchless impedance system). The design of the present invention, which does not require an external patch, eliminates external noise from the patch and / or noise from the patch wire, as well as noise along the tissue pathway between the electrode and the patch. Furthermore, the design of the present invention facilitates the collection of more impedance data, improves accuracy, and as a result, allows for better determination of the electrode's tissue proximity. Also, more impedance data makes it easier to detect open or short circuits between electrodes. In some embodiments, the impedance is the bipolar electrode composite impedance (BECI).

[0017] In some embodiments, the catheter electrodes are part of a catheter having a circular design or a circular basket / balloon. In an exemplary catheter having eight electrodes, the method and system of the present application facilitate the collection of eight impedance measurements. Electrode pairings may include overlapping pairs so that impedance values ​​can be collected between, for example, electrode 1 and electrode 2, electrode 2 and electrode 3, and electrode 3 and electrode 4. This is in contrast to a design where the electrode pairs do not overlap, and in the case of a four-electrode design, the pairs are limited to electrodes 1 and 2, and electrodes 3 and 4.

[0018] FIG. 1 is a schematic diagram of a system 100 including a medical device 102 and a local system 103. In some embodiments, the local system 103 includes a switch 108, a digital / analog (DtoA) converter 110, a filter 112, an analog / digital (AtoD) converter 114, a filter 116, a display 130, and an electronic control unit (ECU) 118. The electronic control unit (ECU) 118 may include a signal source 120, a synchronous demodulation circuit 122, a contact determination module 124, a memory 126, and a processor 128.

[0019] In some embodiments, the medical device 102 is an elongated medical device such as a diagnostic and / or therapeutic catheter, an introducer, a sheath, or other similar type of device. The medical device 102 includes a distal end 104, a proximal end (not shown) including a handle operated by a technician, and an interface for interfacing the medical device 102 to the local system 103. The distal end 104 may include various sensors and / or components for localizing / navigating the distal end 104 within the patient, mapping physiological parameters within the patient, and providing therapy. In particular, the distal end 104 of the medical device includes a plurality of electrodes that may be utilized for one or more of these purposes with respect to a patient's organ 106 such as the heart.

[0020] The contact state of one or more electrodes located at the distal end 104 of the medical device 102 is determined based on bipolar electrode complex impedance (BECI) measurements. Generally, a BECI measurement is generated by driving an excitation signal between two electrodes forming a bipolar pair. As a result, the voltage at each electrode is measured and utilized to derive a complex impedance signal. The contact determination module 124 utilizes the measured BECI measurements to determine the contact state or tissue proximity.

[0021] In the embodiment shown in FIG. 1, signal source 120 is utilized to generate an excitation signal. In some embodiments, signal source 120 generates one or more excitation signals or drive signals, each having a unique frequency. More specifically, in one embodiment, signal generator 120 may generate a plurality of excitation signals or drive signals having unique frequencies within a range from about 1 kHz to greater than 500 kHz, more typically within a range from about 2 kHz to 200 kHz, and even more typically within a range from about 10 kHz to about 20 kHz. Each drive signal may, in one embodiment, have a constant current typically within a range from 1 to 200 μA, more typically about 5 μA. Signal generator 120 may also generate signals involved in determining the position of electrodes within a patient's body that may be utilized, for example, for mapping, navigation, and / or therapy delivery. The digital signals generated by signal source 120 are converted to analog signals by D-A converter 110 and supplied to selected bipolar electrodes via filter 112 and switch 108. In response to the analog signal supplied between the selected bipolar electrodes, the resulting voltage is measured at the electrode pair by switch 108, filter 116, A-D converter 114, and synchronous demodulation circuit 122. In some embodiments, switch 108 selects the electrodes to be monitored in response to the supplied excitation signal or drive signal. Filter 116 and A-D converter 114 convert the analog signal to a digital signal operable by ECU 118. Synchronous demodulation circuit 122 separates the signals from each other based on the frequency of the excitation signal or drive signal and enables a plurality of bipolar electrode pairs to be analyzed substantially simultaneously based on the plurality of excitation signals or drive signals supplied to the electrode pairs.

[0022] In some embodiments, memory 126 may be configured to store data for the medical device 102, the patient, and / or other data (e.g., calibration data). Such data may be known before the medical procedure (e.g., medical device-specific data, number of catheter electrodes) or may be determined and stored during the procedure. Memory 126 may also be configured to store instructions that, when executed by the processor 128 and / or the contact determination module 124, cause the ECU 118 to perform one or more methods, steps, functions, or algorithms described herein. For example, but not limited to, memory 126 may include data and instructions for determining the impedance of one or more electrodes on the medical device 102 (e.g., bipolar electrode composite impedance or BECI measurement) and utilizing the impedance measurement to determine the contact state of one or more electrodes. In some embodiments, the contact determination module 124 utilizes a processor, application-specific integrated circuit (ASIC), or other type of processor to execute instructions stored in memory 126. The ECU may be connected to a display 130, which may display an output of the determined contact state of one or more electrodes of a sensed tissue (e.g., heart), a medical device (not shown), and / or a medical device 102.

[0023] Figure 2 is an isometric view of the catheter 200. The catheter 200 is an example of a medical device that may be used in the system 100 of Figure 1. In some embodiments, the catheter 200 is a cardiac catheter. In some embodiments, the catheter 200 includes a primary shaft 202, a secondary shaft 206, and a basket assembly 201. In some embodiments, the secondary shaft 206 extends through the primary central shaft lumen of the primary shaft 202. The basket assembly 201 includes a plurality of splines 210a, 210b, 210c, 210d, 210e, 210f, and 210h (collectively, spline 210), the proximal ends of which are connected to the distal end 204 of the primary shaft 202 and the distal ends of which are connected to the distal end of the secondary shaft 206. At the angle shown in Figure 2, spline 210g is not visible. The plurality of splines 210 can be expanded by moving the secondary shaft 206 into the primary shaft 202. In some embodiments, each of the multiple splines 210 includes at least one corresponding electrode 212a, 212b, 212c, 212d, 212e, 212f, and 212h (collectively electrode 212). Again, electrode 212g located on spline 210g is not visible. In other embodiments, catheter 200 may include additional electrodes not shown in Figure 2, for example, catheter 200 may include electrodes proximal and / or distal to the basket assembly 201.

[0024] In some embodiments, impedance measurements may be performed between overlapping pairs of adjacent electrodes on the catheter 200, for example, between electrodes 212a and 212b, between electrodes 212b and 212c, between electrodes 212c and 212d, etc. Impedance measurements may also be performed between adjacent electrodes 212h and 212a. In this way, two impedance measurements may be generated for each electrode (for example, for electrode 212b, a first impedance measurement is performed between electrode pair 212a-212b and a second impedance measurement is performed between electrode pair 212b-212c). By overlapping electrode pairs, in embodiments utilizing eight electrodes (as shown in Figure 2), eight impedance measurements can be collected for the catheter 200, and these eight measurements can be used to determine the contact state or tissue proximity of the electrodes 212. As will be discussed later, more impedance data means greater accuracy in determining tissue proximity and more data to determine whether the various electrodes 212 are functioning correctly.

[0025] Figure 3 is a schematic diagram showing the circuit elements for measuring the impedance between electrode pairs 212 of catheter 200 in Figure 2, and does not include surface patch electrodes. Three measurement circuits 310A, 310B, and 310C are shown in Figure 3, each containing a pair of electrodes. Electrodes 1, 2, 3, and 4 in Figure 3 correspond to electrodes 212a, 212b, 212c, and 212d of catheter 200 in Figure 2, respectively. Specifically, Figure 3 shows three electrode pairs: a first pair between electrode 1 and electrode 2, a second pair between electrode 2 and electrode 3, and a third pair between electrode 3 and electrode 4. Additional measurement circuits not shown in Figure 3 can be used to measure the impedance of the remaining electrode pairs of electrodes 5-8 (212e-212h). Each measurement circuit 310A, 310B, and 310C contains R OTHER It also includes two resistors labeled as such. Each electrode 1, 2, 3, and 4 has R FILTER This also includes filters that display as such.

[0026] Variable impedance Z 12 This represents the impedance through the blood pool and / or tissue between electrode 1 and electrode 2. Similarly, the variable impedance Z 23 This represents the impedance through the blood pool and / or tissue between electrode 2 and electrode 3, and the variable impedance Z 34 This represents the impedance through the blood pool and / or tissue between electrode 3 and electrode 4. The impedance measurement is used to determine tissue contact or proximity, i.e., whether each electrode is located in the blood pool (in which case the measured impedance will be low) or adjacent to the tissue (in which case the measured impedance will be high).

[0027] In some embodiments, measurement circuit 310A is configured to measure the impedance between electrodes 1 and 2 and includes a drive signal or signal generator 120A; measurement circuit 310B is configured to measure the impedance between electrodes 2 and 3 and includes a drive signal or signal generator 120B; and measurement circuit 310C is configured to measure the impedance between electrodes 3 and 4 and includes a drive signal or signal generator 120C. Each of measurement circuits 310A, 310B, and 310C includes operational amplifiers 314A, 314B, and 314C, respectively.

[0028] The first operational amplifier 314A includes a first terminal (i.e., positive terminal) connected to electrode 1 and a second terminal (i.e., negative terminal) connected to electrode 2. The output of operational amplifier 314A, labeled channel 1-2, reflects the voltage difference between electrode 1 and electrode 2. The voltage difference between electrode 1 and electrode 2 is the impedance Z between electrode 1 and electrode 2. 12 This is related to the impedance Z 12 This relates to whether electrodes 1 and 2 are located in the blood pool or adjacent to tissue. The second operational amplifier 314B includes a first terminal connected to electrode 2 and a second terminal connected to electrode 3. The output of operational amplifier 314B, labeled channel 2-3, reflects the voltage difference between electrodes 2 and 3. The voltage difference measured by operational amplifier 314B is the impedance Z between electrodes 2 and 3. 23is related. The third operational amplifier 314C includes a first terminal connected to electrode 3 and a second terminal connected to electrode 4. The output of the operational amplifier 314C labeled as channel 3-4 reflects the voltage difference between electrode 3 and electrode 4. The voltage difference measured by the operational amplifier 314C is related to the impedance Z between electrode 3 and electrode 4 34 is related. The outputs of operational amplifiers 314A, 314B, and 314C are each supplied to ADC114 for digital conversion and then supplied to ECU118 (see Figure 4) to determine the measured impedance of each electrode pair. Based on the measured impedance, ECU118 determines the contact state of each electrode or the proximity of the tissue. In some embodiments, ECU118 may also utilize the measured impedance to detect the defective states (e.g., short circuit, open circuit, etc.) of the electrodes.

[0029] Depending on the catheter design, some or all of the electrodes may be part of two different measurement circuits respectively. For example, electrode 2 is paired with electrode 1 in measurement circuit 310A and paired with electrode 3 in measurement circuit 310B. In other words, electrode 2 is the common electrode between measurement circuits 310A and 310B. As shown in FIG. 3, electrode 4 is paired with electrode 3 in measurement circuit 310C, but electrode 4 can also be paired with electrode 5 in an additional measurement circuit not shown in FIG. 3. Similarly, electrodes 5 to N can be paired in additional measurement circuits, where "N" is the total number of electrodes on the catheter.

[0030] In the basket design of catheter 200 shown in Figure 2, each of the eight electrodes can be part of two different measurement circuits; that is, the last electrode pairing is electrodes 8 and 1 (i.e., electrodes 212h and 212a). Thus, in the example of catheter 200, there are eight electrode pairings and eight impedance measurements. In other embodiments, the number of pairings and impedance measurements is equal to the total number of electrodes.

[0031] In some embodiments, each measurement circuit 310A, 310B, and 310C includes its own drive signal / signal generator 120A, 120B, and 120C, respectively. In some embodiments, the signal generators 120A, 120B, and 120C can operate sequentially. In some embodiments, the signal generators 120A, 120B, and 120C can operate simultaneously. By time-slicing the channels to avoid overlapping channel drives, a single frequency can be used between measurement circuits 310A, 310B, and 310C. Drive signals can also be multiplexed. Drive signals can be intermittent. When used in conjunction with other measurements such as magnetic measurements, it may be necessary to blank (turn off) the drives to avoid interference. In some embodiments, different modulation frequencies can be used for circuits 310A, 310B, and 310C. In some embodiments, the AC signals for generators 120A, 120B, and 120C are provided at approximately 17 kHz, each separated by a given frequency (e.g., 25 Hz). For example, the AC signal from generator 120A is 17.300 kHz, the AC signal from generator 120B is 17.325 kHz, and the AC signal from generator 120C is 17.350 kHz.

[0032] In other embodiments, the measurement circuits 310A, 310B, and 310C can share a signal generator. A single frequency can be used among the various measurement circuits 310A, 310B, and 310C if the channels are time-sliceable.

[0033] As described above, each electrode can be part of two measurement circuits. Similarly, each electrode can be connected to two signal generators. For example, electrode 2 can be connected in common to two adjacent signal generators, namely signal generator 120A and signal generator 120B. Thus, electrode 2 becomes a common electrode between signal generators 120A and 120B. Each electrode can be connected to two operational amplifiers. For example, electrode 2 can be connected in common to two adjacent operational amplifiers, operational amplifier 314A and operational amplifier 314B.

[0034] Using the method and system of this application, the impedance between electrode pairs is measured directly by the impedance within the blood pool / tissue. All sources of variability, such as resistance paths from external patches and wires between electrodes and patches, are eliminated in the design of the present invention. In surface patch designs, variable resistance and unbalanced loads between electrode pairs can lead to inaccurate impedance measurements. Furthermore, patch designs provide little information about adjacent but unpaired electrodes.

[0035] Using the method and system of this application, which includes overlapping pairs, more impedance data can be collected, leading to better determination of tissue proximity. Furthermore, the method and system of this application facilitates better detection of defective electrodes and / or defective circuits.

[0036] Figure 4 is a schematic diagram of the components of system 100, including the ADC 114 and ECU 118 which process the channel outputs from the operational amplifiers 314A, 314B, and 314C of Figure 3. The analog outputs pass through the ADC 114 and are converted to digital outputs which are received by the ECU 118. In some embodiments, the ECU 118 includes a short-circuit module 132, an open-circuit module 134, and a tissue proximity detection module 136.

[0037] The ECU 118 can use impedance measurements of each electrode pair to detect the presence of a defective electrode or defective circuit. For example, a short circuit occurs when a pair of electrodes are physically in contact with each other, and an open circuit occurs when there is a break in the electrical path of a particular electrode. If a short circuit is detected by the short circuit module 132, a notification can be generated on the display 130 (see Figure 1) to warn the user of the system 100 of the short circuit. Similarly, if an open circuit is detected by the open circuit module 134, a notification can be generated on the display 130 to warn the user of the system 100 of the open circuit. Additional details for detecting short circuits or open circuits are provided below with reference to Figures 6 and 7. Similarly, the ECU 118 can use impedance measurements of each electrode pair to detect tissue proximity, i.e., whether the electrodes are adjacent to tissue or in a blood pool. The tissue proximity detection module 136 can determine the tissue proximity state, and the module 136 can generate a notification which can be transmitted to the display 130.

[0038] Figure 5 is a flowchart showing the steps in Method 500 for measuring the impedance of each electrode pairing of multiple electrodes on a medical device when the medical device is inside a patient's body. In some embodiments, the medical device is a catheter, and the electrodes are located at the distal end of the catheter. In step 502, Method 500 includes applying a drive signal between adjacent electrode pairs. Electrode pairings overlap such that at least some of the electrodes of the multiple electrodes are included in two measurement circuits. In some embodiments, all electrodes are included in two measurement circuits, and the number of pairings is equal to the total number of electrodes in the medical device. In some embodiments, each drive signal applied in step 502 is applied simultaneously to multiple electrodes using frequency division multiplexing (i.e., each drive signal is applied at a unique frequency). In other embodiments, each drive signal is applied at different times using time division multiplexing.

[0039] In step 504, an impedance measurement is calculated for each electrode pair. In step 506, the measured impedance is compared to a threshold to determine the tissue proximity of the paired electrodes. In some embodiments, if the measured impedance is below the threshold, the electrode is determined to be not in contact with tissue (i.e., in the blood pool), and if the measured impedance is above the threshold, the electrode is determined to be close to or adjacent to tissue. In some embodiments, the terms “contact state” or “tissue proximity” are binary decisions, where the electrode is either “in contact” or “not in contact” with tissue. In other embodiments, tissue proximity may include additional contact states such as “intermittent contact.” In step 508, the determined tissue proximity results are displayed for each electrode pair on a display 130 (Figure 1), for example.

[0040] Figure 6 is a flowchart showing the steps of method 600 used to detect a defective electrode or defective circuit in a medical device having multiple electrodes. In addition to determining tissue proximity, the measured impedance can also be used to detect whether the electrodes are functioning properly. In step 602, a drive signal is applied between each of the multiple electrode pairs. As described above, the drive signal may be applied simultaneously to each of the multiple electrode pairs using frequency division multiplexing, or the drive signal may be applied one at a time to each of the multiple electrode pairs (at the same frequency). In step 604, an impedance measurement is calculated for each electrode pair. As described above, the electrode pairs are duplicated, and the number of pairs is equal to either the total number of electrodes on the catheter or one less than the total number of electrodes, depending on the catheter design.

[0041] In step 606, the measured impedance value is used to detect one or more defect conditions, including, for example, short-circuit defects and / or open-circuit defects. In some embodiments, the defect detection described in Figure 6 is analyzed continuously in response to the measured impedance value. In some embodiments, defect detection is provided only at startup / initialization. In some embodiments, a defect detected in one of a plurality of electrode pairs (e.g., a short-circuit defect) prevents the measured impedance from being used for tissue detection. In some embodiments, defect determination is performed on a pair-by-pair basis. That is, a defect detected in relation to the pairing of electrode 2 and electrode 3 will invalidate the tissue proximity detection of that electrode 2 and electrode 3 pair, but the detected defect does not prevent the impedance measurements related to the pairing of electrode 1 and electrode 2, or electrode 3 and electrode 4, from being used to detect tissue proximity.

[0042] In step 608, if no defects were detected in step 606, impedance measurements are used to detect the proximity of tissue.

[0043] Figure 7 is a flowchart showing further analysis following step 606 to determine whether a defect has been detected. Steps 702 and 710 in Figure 7 can be performed for each electrode pairing and its corresponding measured impedance value.

[0044] In step 702, the measured impedance is compared to a minimum threshold. In some embodiments, the minimum threshold is a predetermined value. In other embodiments, the minimum threshold may be set or determined based on a previous measurement (e.g., a baseline measurement). In some embodiments, the minimum threshold is equal to or less than the impedance measured when the electrodes are located in the blood pool. In other embodiments, the minimum threshold is significantly smaller than the measured or expected impedance between the electrodes in the blood pool (e.g., nearly zero ohms). Generally, the impedance measured when the electrodes are in the blood pool represents the lowest impedance condition. An impedance below this value indicates a short-circuit fault condition (typically resulting from the electrodes making electrical contact with each other).

[0045] If the measured impedance is less than a minimum threshold in step 702, a short circuit is detected in step 704, and a notification regarding the detected short circuit is generated in step 706. In some embodiments, the notification generated in step 704 identifies both the type of defect detected and the electrode associated with the defect. For example, if the measured impedance is related to electrode 2 and electrode 3, the notification generated in step 706 will identify both the type of defect detected (e.g., a short circuit) and the electrode pair associated with that defect.

[0046] In step 708, tissue proximity detection is disabled for electrode pairs identified as having a short circuit. In other words, the measured impedance for that electrode pair is discarded to determine the tissue proximity or contact state.

[0047] In step 702, if the measured impedance value is not less than the minimum threshold, in step 710, the measured impedance is compared to the maximum threshold value. In some embodiments, the maximum threshold value is a predetermined value greater than any of the expected impedances measured between electrode pairs. In step 710, if the measured impedance is greater than the maximum threshold value, it indicates a possible open-circuit defect. In some embodiments, if the measured impedance is greater than the maximum threshold in step 710, in step 712, the measured impedance associated with adjacent electrode pairs is used to determine whether a particular electrode is an open-circuit defect.

[0048] If the answer in step 710 is "YES", then in step 712, further analysis is performed to determine which electrode of the electrode pair is an open circuit. For example, returning to Figure 3, if the measured impedance values ​​of electrodes 2 and 3 (measurement circuit 310B) are higher than the maximum threshold, then either electrode 2 or electrode 3 may be an open circuit. The measured impedance values ​​of measurement circuit 310A (electrodes 1 and 2) and measurement circuit 310C (electrodes 3 and 4) can be seen in step 712. If the impedance value of measurement circuit 310A is also above the maximum threshold, but the impedance value of measurement circuit 310C is below the maximum threshold, then the common electrode between the two high-impedance circuits is electrode 2. In that example, step 712 includes determining that electrode 2 is an open circuit. Step 714 includes generating a notification that an open circuit has been detected. In some embodiments, the notification may identify which electrode on the catheter has an open circuit.

[0049] In step 716, tissue proximity detection is disabled for electrodes identified as having an open circuit, and those electrodes are discarded to determine whether they are in tissue proximity or contact.

[0050] If the answer for both decision points 702 and 710 is "NO" for all electrode pairings, step 718 generates a "No defects detected" notification. In some embodiments, such notifications in step 718 (as well as steps 706 and 714) may include visual and / or audible warnings on display 130.

[0051] By having overlapping electrode pairs (1 and 2; 2 and 3; 3 and 4) compared to separate pairings (1 and 2, 3 and 4), the method and system of the present invention facilitates better detection of both short and open circuits. In a design where impedance is measured only between electrodes 1 and 2 and between electrodes 3 and 4, a short between electrodes 2 and 3 will not be detected. In contrast, the design of the present invention, by measuring the impedance of the overlapping electrode pairs, facilitates the detection of a short circuit between electrodes 2 and 3. Similarly, if an open circuit is detected based on a high impedance value of an electrode pairing, the method and system of the present invention facilitates the decoding of which electrode in the electrode pairing has the open circuit.

[0052] Although the present invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various modifications may be made and equivalents may be substituted for their elements without departing from the scope of the invention. Furthermore, many modifications may be made to adapt the teachings of the invention to specific situations or materials without departing from the essential scope of the invention. Accordingly, the present invention is not limited to the specific embodiments disclosed, but is intended to include all embodiments that fall within the scope of the appended claims.

[0053] (Consideration of possible embodiments) The following is a non-exclusive description of possible embodiments of the present invention.

[0054] According to one embodiment, a method for measuring the impedance of multiple electrodes on a medical device, the method comprising: applying a first drive signal between a first electrode and a second electrode to measure a first impedance value between the first electrode and the second electrode; applying a second drive signal between a second electrode and a third electrode to measure a second impedance value between the second electrode and the third electrode; and applying a third drive signal between a third electrode and a fourth electrode to measure a third impedance value between the third electrode and the fourth electrode. Each of the first, second, and third drive signals can be applied by separate signal generators.

[0055] The method described in the preceding paragraph may optionally include, additionally and / or alternatively, one or more of the following features, steps, configurations, and / or additional components:

[0056] In some embodiments, the method may further comprise applying an additional drive signal between an additional electrode pair, where each electrode of the additional electrode pair is connected to the two drive signals.

[0057] In some embodiments, "N" is equal to the total number of electrodes on the medical device, and the Nth drive signal is applied between the first electrode and the Nth electrode.

[0058] In some embodiments, the medical device is a catheter having multiple splines, and multiple electrodes are arranged on the multiple splines.

[0059] In some embodiments, each spline of a plurality of splines includes one or more electrodes.

[0060] In some embodiments, a first electrode is positioned on a first spline of a plurality of splines, a second electrode is positioned on a second spline of a plurality of splines, a third electrode is positioned on a third spline of a plurality of splines, and a fourth electrode is positioned on a fourth spline of a plurality of splines.

[0061] In some embodiments, the first drive signal, the second drive signal, and the third drive signal are applied at different frequencies.

[0062] In some embodiments, the method may further include detecting a defective electrode or defective circuit in a plurality of electrodes based on measured impedance values.

[0063] In some embodiments, detecting a defective electrode or circuit involves detecting a short circuit in an electrode pair if the measured impedance of the electrode pair is below a predetermined minimum threshold.

[0064] In some embodiments, detecting a defective electrode or defective circuit involves detecting an open circuit in an electrode pair when the measured impedance of the electrode pair is higher than a predetermined maximum threshold.

[0065] In another embodiment, a method for detecting a defective electrode or defective circuit in a medical device having a plurality of electrodes at the distal end of the medical device, the method comprising applying a first drive signal between a first adjacent electrode pair in the plurality of electrodes, and applying a second drive signal between a second adjacent electrode pair in the plurality of electrodes. The first and second adjacent electrode pairs may include a common electrode. The method further comprises applying an additional drive signal between an additional adjacent electrode pair, measuring the impedance of each of the adjacent electrode pairs, and using the measured impedances to detect a defective electrode or defective circuit in the plurality of electrodes.

[0066] The method described in the preceding paragraph may optionally include, additionally and / or alternatively, one or more of the following features, steps, configurations, and / or additional components:

[0067] In some embodiments, utilizing a measured impedance to detect a defective electrode or circuit includes detecting a short circuit in an electrode pair if the measured impedance of the electrode pair is below a predetermined minimum threshold.

[0068] In some embodiments, detecting a defective electrode or circuit using measured impedance involves detecting an open circuit in an electrode pair when the measured impedance of the electrode pair is higher than a predetermined maximum threshold.

[0069] In some embodiments, the method further comprises reviewing the measured impedances of adjacent electrode pairs to determine which electrode of the electrode pair has an open circuit.

[0070] In some embodiments, the method further comprises generating a notification in the utilization step indicating whether a defective electrode or defective circuit has been detected.

[0071] In another embodiment, a system for use with a medical device configured to be inserted into a patient and having a plurality of electrodes at the distal end of the medical device, the system comprising a plurality of measurement circuits, each measurement circuit configured to apply a drive signal to one pair of electrodes from the plurality of electrodes and measure the response of the one pair of electrodes associated with the drive signal. The system further comprises an electronic control unit (ECU) configured to generate an impedance value for each pair of electrodes based on the measured response. One or more electrodes from the plurality of electrodes are part of two measurement circuits such that adjacent measurement circuits have a common electrode.

[0072] The system described in the preceding paragraph may optionally include, additionally and / or alternatively, one or more of the following features, steps, configurations, and / or additional components:

[0073] In some embodiments, all electrodes of a plurality of electrodes are part of two measurement circuits.

[0074] In some embodiments, the ECU is configured to detect at least one of a defective electrode in a plurality of electrodes and a defective pairing in a plurality of electrodes.

[0075] In some embodiments, the ECU includes a short-circuit module configured to detect short circuits between electrode pairs in multiple electrodes.

[0076] In some embodiments, the ECU includes an open-circuit module configured to detect open circuits in multiple electrodes.

Claims

1. A method for measuring the impedance of multiple electrodes on a medical device, The aforementioned method, A first drive signal is applied between the first electrode and the second electrode, and a first impedance value is measured between the first electrode and the second electrode. A second drive signal is applied between the second electrode and the third electrode to measure the second impedance value between the second electrode and the third electrode, The method includes applying a third drive signal between the third electrode and the fourth electrode and measuring the third impedance value between the third electrode and the fourth electrode, The first drive signal, the second drive signal, and the third drive signal are each applied by separate signal generators. method.

2. The method further comprises applying an additional drive signal between an additional electrode pair, The method according to claim 1, wherein each electrode of the additional electrode pair is connected to two drive signals.

3. "N" is equal to the total number of electrodes on the medical device. The method according to claim 1 or 2, wherein the Nth drive signal is applied between the first electrode and the Nth electrode.

4. The medical device is a catheter having multiple splines, The method according to any one of claims 1 to 3, wherein the plurality of electrodes are arranged on the plurality of splines.

5. The method according to claim 4, wherein each spline of the plurality of splines includes one or more electrodes.

6. The first electrode is positioned on the first spline of the plurality of splines, The second electrode is positioned on the second spline of the plurality of splines, The third electrode is positioned on the third spline of the plurality of splines, The method according to claim 4, wherein the fourth electrode is arranged on the fourth spline of the plurality of splines.

7. The method according to any one of claims 1 to 4, wherein the first drive signal, the second drive signal, and the third drive signal are applied at different frequencies.

8. The method according to any one of claims 1 to 4, further comprising detecting a defective electrode or defective circuit in the plurality of electrodes based on each measured impedance value.

9. The method according to claim 8, wherein detecting a defective electrode or defective circuit includes detecting a short circuit in an electrode pair when the measured impedance value of the electrode pair is less than a predetermined minimum threshold.

10. The method according to claim 8, wherein detecting a defective electrode or defective circuit includes detecting an open circuit in an electrode pair when the measured impedance value of the electrode pair is greater than a predetermined maximum threshold.

11. A method for detecting a defective electrode or circuit in a medical device having multiple electrodes at its distal end, Applying a first drive signal between a first adjacent electrode pair among the plurality of electrodes, Applying a second drive signal between a second adjacent electrode pair among the plurality of electrodes, wherein the first adjacent electrode pair and the second adjacent electrode pair include a common electrode, Applying an additional drive signal between an additional pair of adjacent electrodes, Measure the impedance of each adjacent electrode pair, The method includes using the measured impedance to detect a defective electrode or defective circuit in the plurality of electrodes, method.

12. The method according to claim 11, wherein detecting a defective electrode or circuit using the measured impedance of each electrode pair comprises detecting a short circuit of the electrode pair if the measured impedance of the electrode pair is below a predetermined minimum threshold.

13. The method according to claim 11 or 12, wherein the detection of a defective electrode or defective circuit using the measured impedance of each electrode pair is further comprising detecting an open circuit of the electrode pair if the measured impedance of the electrode pair is greater than a predetermined maximum threshold.

14. The method according to claim 13, further comprising reviewing the measured impedance of adjacent electrode pairs to determine which electrode of the electrode pair has an open circuit.

15. The method according to any one of claims 11 to 14, further comprising generating a notification of whether a defective electrode or defective circuit has been detected.

16. A medical device configured to be inserted into a patient, and a system used in conjunction with the medical device having multiple electrodes at its distal end, A plurality of measurement circuits, each measurement circuit configured to apply a drive signal to a pair of electrodes among the plurality of electrodes and measure the response of the electrode pair related to the drive signal, The system comprises an electronic control unit (ECU) configured to generate impedance values ​​for each electrode pair based on the measured response, A system in which one or more of the plurality of electrodes are part of two measuring circuits such that adjacent measuring circuits have a common electrode.

17. The system according to claim 16, wherein all of the plurality of electrodes are part of two measuring circuits.

18. The system according to claim 16 or 17, wherein the ECU is configured to detect at least one of a defective electrode in the plurality of electrodes and a defective pairing in the plurality of electrodes.

19. The system according to claim 18, wherein the ECU comprises a short-circuit module configured to detect short circuits between electrode pairs in the plurality of electrodes.

20. The system according to claim 18, wherein the ECU comprises an open-circuit module configured to detect open circuits in the plurality of electrodes.

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