Method and apparatus for monitoring conductive system pacing

Abstract

A medical device (50) is configured to obtain at least a first electrocardiogram (ECG) signal by processing circuitry of the medical device (50). The processing circuitry may determine a ventricular activation time (VAT) using the first ECG signal for each of a plurality of pacing pulses and detect a threshold difference between a first VAT associated with a first of the plurality of pacing pulses and a second VAT associated with a second of the plurality of pacing pulses. The medical device (50) may be configured to display the determined VAT.

Description

Technical Field

[0001] The present disclosure relates to medical devices and methods for monitoring conduction system pacing of a patient's heart. Background Art

[0002] During normal sinus rhythm (NSR), the heartbeat is regulated by electrical signals generated by the sinoatrial (SA) node located in the wall of the right atrium. Each depolarization signal generated by the SA node spreads in the atrium, causing depolarization and contraction of the atrium, and reaches the atrioventricular (AV) node. The AV node propagates the depolarization signal through the His bundle of the atrioventricular septum, and thereafter reaches the bundle branches and Purkinje muscle fibers of the right and left ventricles to respond, which is sometimes referred to as the "His-Purkinje system".

[0003] Patients experiencing conduction system abnormalities (e.g., poor AV node conduction, poor SA node function, or other conduction abnormalities) may receive a pacemaker to restore a more normal heart rhythm and synchronization of the heart chambers. Ventricular pacing may be performed to maintain the ventricular rate in patients with atrioventricular conduction abnormalities. A single-chamber ventricular pacemaker may be coupled to a transvenous ventricular lead carrying an electrode placed in the right ventricle (RV) (e.g., in the apex of the right ventricle). The pacemaker itself is typically implanted in a subcutaneous pocket, with the transvenous ventricular lead tunneled into the subcutaneous pocket. Intracardiac pacemakers have been introduced or proposed for complete implantation within the patient's heart, thereby eliminating the need for a transvenous lead. An intracardiac pacemaker may provide sensing and pacing from within a chamber of the patient's heart, such as from within the right ventricle of a patient with an AV conduction block.

[0004] A dual chamber pacemaker may be provided that includes a transvenous atrial lead carrying an electrode placed in the right atrium and a transvenous ventricular lead carrying an electrode placed in the right ventricle via the right atrium. The dual chamber pacemaker senses atrial and ventricular electrical signals and can provide both atrial pacing and ventricular pacing as needed to promote normal atrial and ventricular rhythms and to promote AV synchronization when SA and / or AV node or other conduction abnormalities are present.

[0005] It has been found that ventricular pacing via an electrode at or near the apex of the right ventricle is associated with an increased risk of atrial fibrillation and heart failure. Alternative pacing sites have been studied or proposed, such as pacing of the His bundle or left bundle branch. Ventricular pacing along the His-Purkinje conduction system has been proposed to provide a more physiological form of ventricular pacing, because the pacing-induced depolarization can proceed along the native conduction system of the heart. Pacing the ventricles via the His bundle or left bundle branch, for example, allows recruitment along the native conduction system of the heart (including bundle branches and Purkinje fibers), and is hypothesized to promote more physiologically normal cardiac excitation than other pacing sites (such as the ventricular apex). Summary of the invention

[0006] The technology disclosed herein generally relates to a medical device system for monitoring the pacing of the His-Purkinje conduction system (also referred to herein as the "conduction system") of a patient's heart. Conduction system pacing (CSP) can be delivered by placing at least one electrode along or near the His-Purkinje conduction system, the at least one electrode can be along the His bundle and / or along one or both of the left bundle branch (LBB) and / or the right bundle branch (RBB) or near one or both. In various examples, a medical device operated according to the methods disclosed herein receives an input signal from an electrode (e.g., a surface electrocardiogram (ECG) electrode), determines a differential ECG signal from the signal input, and determines a ventricular activation time based on the differential ECG signal, the differential ECG signal can be a unipolar or bipolar ECG signal. The ventricular activation time (VAT) can be determined based on the delivered CSP pulse to a reference point of the ECG signal. The medical device can be configured to display a visual representation of the VAT in a graphical user interface (GUI). The VAT may be determined for a plurality of cardiac cycles during which CSP pulses are delivered by the medical device or by a second medical device, such as an implantable pacemaker.

[0007] When the CSP pulse captures at least a portion of the conduction system, the VAT is expected to change suddenly, such as decrease. The VAT determined for multiple cardiac cycles can be presented to the clinician or user in a visual display with a prominent indicator (e.g., a change in VAT formatting or other visual and / or auditory notification), presented to the user to notify the user of the detected change in the determined VAT. The change in the determined VAT can indicate a change in the capture of the conduction system (e.g., successful capture or failed capture). The techniques disclosed herein for determining changes in VAT and / or other metrics determined based on one or more ECG signals can provide guidance to the user in positioning at least one electrode and / or adjusting CSP parameters to achieve CSP capture during an implantation procedure.

[0008] In one example, the present disclosure provides a medical device comprising a processor configured to obtain one or more ECG signals. The processor may be configured to: for each pacing pulse in a plurality of pacing pulses, determine a ventricular excitation time using a first ECG signal in the one or more ECG signals; determine a difference between the ventricular excitation time and a previously determined ventricular excitation time; and determine when the difference meets a threshold difference. The medical device may include a display unit that communicates with the processor. The display unit may be configured to: display at least one ECG signal in the one or more ECG signals; display at least one of the ventricular excitation time or the determined difference; and display a prominent indicator in response to determining that the threshold difference is met.

[0009] In another example, the present disclosure provides a method, the method comprising: obtaining one or more ECG signals; and for each pacing pulse in a plurality of pacing pulses, using a first ECG signal of the one or more ECG signals to determine a ventricular activation time; determining a difference between the ventricular activation time and a previously determined ventricular activation time; and determining when the difference meets a threshold difference. The method may also include: displaying at least one of the one or more ECG signals; displaying at least one of the determined ventricular activation time or the determined difference; and in response to determining that the threshold difference is met, displaying a prominent indicator.

[0010] In another example, the present disclosure provides a non-transitory computer-readable medium storing instructions that, when executed by a processing circuit system of a medical device, cause the medical device to obtain one or more ECG signals. For each pacing pulse in a plurality of pacing pulses, the instructions cause the medical device to: use a first ECG signal of the one or more ECG signals to determine a ventricular activation time; determine a difference between the ventricular activation time and a previously determined ventricular activation time; and determine when the difference meets a threshold difference. The instructions also cause the medical device to: display at least one of the one or more ECG signals; display at least one of the determined ventricular activation time or the determined difference; and display a prominent indicator in response to determining that the threshold difference is met.

[0011] The present invention also discloses the following embodiments:

[0012] Embodiment 1. A medical device, the medical device comprising a processor configured to obtain one or more ECG signals. The processor is further configured to: for each pacing pulse in a plurality of pacing pulses, determine a ventricular activation time using a first ECG signal in the one or more ECG signals; determine a difference between the ventricular activation time and a previously determined ventricular activation time; and determine that the difference satisfies a threshold difference. The medical device also includes a display unit that communicates with the processor and is configured to: display at least one of the one or more ECG signals; display at least one of the ventricular activation time or the determined difference; and display a prominent indicator in response to determining that the threshold difference is met.

[0013] Embodiment 2. A medical device according to embodiment 1, wherein the processor is further configured to obtain the first ECG signal by the following steps: receiving four input signals from a reference electrode and each of three chest electrodes, the three chest electrodes including a left chest electrode and a right chest electrode; determining a central terminal signal based on the four input signals; and determining the first unipolar ECG signal as the difference between the input signal from the left chest electrode and the central terminal signal.

[0014] Embodiment 3. A medical device according to Embodiment 2, wherein the processor is further configured to obtain the first ECG signal through the following steps: determining a second unipolar ECG signal based on the input signal; and determining the first ECG signal as a bipolar ECG signal by determining the difference between the first unipolar ECG signal and the second unipolar ECG signal.

[0015] Example 4. A medical device according to Example 2, wherein the processor is further configured to obtain the one or more ECG signals by determining a second unipolar ECG signal as the difference between the input signal from the right chest electrode and the central terminal signal, and the display unit is further configured to display multiple cardiac cycles of the second unipolar ECG signal, the multiple cardiac cycles corresponding to at least a portion of the multiple pacing pulses and being temporally aligned with corresponding ventricular excitation times determined for at least this portion of the multiple pacing pulses.

[0016] Example 5. A medical device according to claim 1, 2, 3 or 4, wherein the processor and the display unit are also configured to simultaneously display multiple cardiac cycles and multiple determined ventricular excitation times of at least one ECG signal among the obtained ECG signals, wherein the multiple cardiac cycles and the multiple ventricular excitation times of the at least one ECG signal among the obtained ECG signals correspond to at least a portion of the multiple pacing pulses.

[0017] Embodiment 6. A medical device according to Embodiment 1, 2, 3 or 4, wherein the processor and the display unit are further configured to continuously display each of a plurality of cardiac cycles of at least one of the obtained ECG signals, each of the plurality of cardiac cycles being displayed one at a time individually together with a corresponding determined ventricular excitation time, the plurality of cardiac cycles corresponding to at least a portion of the plurality of pacing pulses.

[0018] Embodiment 7. The medical device of embodiment 1, wherein the processor is further configured to determine each of the ventricular activation times by: identifying a reference point of the first ECG signal after a corresponding one of the plurality of pacing pulses; and determining the ventricular activation time as a time interval from a corresponding one of the plurality of pacing pulses to the reference point. The display unit is further configured to display the first ECG signal and a visual marker of at least one of the identified reference points of the first ECG signal together with the determined ventricular activation time.

[0019] Embodiment 8. The medical device according to embodiment 1, wherein the processor is further configured to determine when a ventricular activation time in the determined ventricular activation times is greater than a threshold ventricular activation time. The display unit is further configured to display each of the ventricular activation times that is determined to be greater than the threshold ventricular activation time according to a first format, and each of the ventricular activation times that is less than the threshold ventricular activation time according to a second format different from the first format.

[0020] Embodiment 9. The medical device of embodiment 1, wherein the processor is further configured to obtain the one or more ECG signals by receiving a plurality of input signals from at least a right chest electrode, a left chest electrode, and a reference electrode, the one or more ECG signals including the first ECG signal associated with the left chest electrode and the second ECG signal associated with the right chest electrode. The processor is further configured to determine a QRS width using the second ECG signal for at least one pacing pulse of the plurality of pacing pulses. The display unit is further configured to display the determined QRS width.

[0021] Embodiment 10. The medical device of embodiment 1, wherein the processor is further configured to obtain the one or more ECG signals by receiving multiple input signals from at least a right chest electrode, a left chest electrode, and a reference electrode, the multiple ECG signals including the first ECG signal associated with the left chest electrode and the second ECG signal associated with the right chest electrode. The processor is also configured to determine, for at least one pacing pulse of the multiple pacing pulses, at least one of a QRS area using the second ECG signal, a peak interval between maximum peaks of the first ECG signal and the second ECG signal, or a QRS morphology metric. The display unit may also be configured to display at least one of the QRS area, the peak interval, or the QRS morphology metric.

[0022] Example 11. A medical device according to Example 1, wherein the display unit is further configured to display the conspicuous indicator by at least one of: generating a visual notification, generating an auditory notification, adjusting the format of the determined ventricular excitation time to be different from the previously displayed ventricular excitation time, and / or adjusting the background of the determined ventricular excitation time.

[0023] Example 12. The medical device of Example 1 further comprises a pulse generator configured to deliver the plurality of pacing pulses via a conduction system pacing electrode.

[0024] Example 13. A medical device according to Example 1, further comprising a telemetry circuit configured to receive a conduction system pacing pulse marker signal from an implantable medical device, the implantable medical device configured to deliver the multiple pacing pulses as conduction system pacing pulses.

[0025] Embodiment 14. The medical device of embodiment 13, wherein the telemetry circuit is further configured to receive a cardiac electrogram signal from the implantable medical device, the implantable medical device being configured to deliver the plurality of pacing pulses as conduction system pacing pulses. The display unit is further configured to display the cardiac electrogram signal.

[0026] Embodiment 15. A method, the method comprising: obtaining one or more ECG signals; and for each pacing pulse in a plurality of pacing pulses, using a first ECG signal of the one or more ECG signals to determine a ventricular activation time; determining a difference between the ventricular activation time and a previously determined ventricular activation time; and determining when the difference meets a threshold difference. The method may also include: displaying at least one of the one or more ECG signals; displaying at least one of the determined ventricular activation time or the determined difference; and in response to determining that the threshold difference is met, displaying a prominent indicator.

[0027] Example 16. A method according to Example 15, wherein obtaining the first ECG signal includes: receiving four input signals from a reference electrode and each of three chest electrodes, the three chest electrodes including a left chest electrode and a right chest electrode; determining a central terminal signal based on the four input signals; and determining the first unipolar ECG signal as the difference between the input signal from the left chest electrode and the central terminal signal.

[0028] Embodiment 17. A method according to Embodiment 16, wherein obtaining the first ECG signal further comprises: determining a second unipolar ECG signal based on the input signal; and determining the first ECG signal as a bipolar ECG signal by determining a difference between the first unipolar ECG signal and the second unipolar ECG signal.

[0029] Example 18. A method according to Example 16, further comprising obtaining the one or more ECG signals by determining a second unipolar ECG signal as the difference between the input signal from the right chest electrode and the central terminal signal; and displaying a plurality of cardiac cycles of the second unipolar ECG signal, the plurality of cardiac cycles corresponding to at least a portion of the plurality of pacing pulses and being temporally aligned with corresponding ventricular excitation times determined for at least that portion of the plurality of pacing pulses.

[0030] Example 19. The method according to Example 15, 16, 17 or 18, further comprising simultaneously displaying a plurality of cardiac cycles and a plurality of determined ventricular excitation times of at least one ECG signal among the obtained ECG signals, wherein the plurality of cardiac cycles and the plurality of ventricular excitation times of the at least one ECG signal among the obtained ECG signals correspond to at least a portion of the plurality of pacing pulses.

[0031] Example 20. According to the medical device described in Example 15, 16, 17 or 18, the method also includes continuously displaying each of a plurality of cardiac cycles of at least one of the obtained ECG signals, each of the plurality of cardiac cycles being displayed one at a time individually together with the corresponding determined ventricular excitation time, and the plurality of cardiac cycles corresponding to at least a portion of the plurality of pacing pulses.

[0032] The details of one or more aspects of the present disclosure are set forth in the following drawings and description. Other features, objectives, and advantages of the techniques described in the present disclosure will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a conceptual diagram of a medical device system capable of sensing and analyzing cardiac electrical signals and displaying a GUI including a VAT determined by a processor receiving the cardiac electrical signals, according to some examples.

[0034] Figure 2 is a conceptual illustration of a pacing lead coupled to an implantable medical device (IMD) capable of pacing a patient's heart and sensing cardiac electrical signals via the pacing lead.

[0035] Figure 3 is a conceptual diagram of an IMD coupled to a CSP lead that is advanced to an alternate location within the heart to deliver CSP pulses and sense cardiac electrical signals.

[0036] Figure 4 is a conceptual diagram of a leadless pacemaker positioned within the right atrium for providing CSP according to another example.

[0037] Figure 5 yes Figure 4 Conceptual diagram of a leadless pacemaker shown implanted in an alternative location for CSP.

[0038] Figure 6 is a schematic diagram of circuitry that may be packaged within an IMD configured to sense cardiac electrical signals and to perform CSP.

[0039] Figure 7 is a flow chart of a method for processing and analyzing ECG signals and generating a GUI for display by a medical device according to some examples.

[0040] Figure 8 is a conceptual diagram of processing circuitry that may be included in a medical device for obtaining differential unipolar and bipolar ECG signals, according to some examples.

[0041] Fig. 9 is an example of a GUI that may be displayed on a display unit of a medical device according to one example.

[0042] Fig.10 is a conceptual diagram of two different screenshots that may be displayed in a GUI at different times by a display unit in coordination with processing circuitry of a medical device according to another example.

[0043] Fig.11 is a flow chart of a method for displaying, by a medical device, data related to a CSP in a GUI according to another example.

[0044] Fig.12 is a diagram of a GUI that may be cooperatively generated by a processor and a display unit of a medical device for display on the display unit according to another example.

[0045] Fig.13 is a conceptual diagram of two different screenshots that may be displayed at different times in a GUI by a display unit of a medical device according to another example. DETAILED DESCRIPTION

[0046] A medical device for receiving, processing, and analyzing at least one ECG signal to monitor capture of at least a portion of a conduction system and the resulting improvement in electrical synchrony of the ventricles is described herein. The ECG signal analysis may be performed by a processing circuit system of the medical device that is configured to receive electrical signals from chest electrodes positioned on a patient during implantation of an implantable pacemaker device configured to deliver CSPs. The ECG signal analysis may be performed during patient follow-up and during capture threshold testing, and may also be performed at any other time when it is desired to confirm CSP capture and / or improve ventricular electrical synchrony due to CSPs.

[0047] As used herein, the term "CSP" refers to the delivery of one or more pacing pulses generated for delivery near a portion of the His-Purkinje conduction system of the heart. A CSP pulse may or may not capture the conduction system, depending on the cathode and anode positions of the CSP electrode vector relative to the conduction system pacing site, the delivered pacing pulse energy, and other factors. Complete or partial His bundle capture, complete or partial LBB capture, and / or complete or partial right bundle branch (RBB) capture are examples of capture of at least a portion of the conduction system. Capture of at least a portion of the conduction system is achieved when the pacing pulse energy delivered with the pacing pulse causes depolarization of tissue of the conduction system. The pacing-induced depolarization occurring at the pacing site can propagate along the conduction system to the ventricular muscle to cause depolarization of the ventricular muscle and subsequent coordinated ventricular contraction.

[0048] The medical devices and techniques disclosed herein provide various improvements in medical device systems that are configured to generate and display various parameters determined from one or more ECG signals that a user may rely on when monitoring and evaluating CSP. The techniques disclosed herein improve the functionality of medical devices in providing a visual representation of CSP data that can be used to guide pacing electrode implantation procedures, test the capture of the conduction system, and monitor improvements in electrical synchrony achieved by CSP.

[0049] Therefore, the technology disclosed herein provides improvements in the computer-related fields of cardiac monitoring and cardiac therapy delivery. By providing a medical device system capable of displaying a GUI according to the technology herein, the complexity and possibility of human error in positioning a pacing electrode at a CSP site and / or selecting CSP parameters to achieve capture of at least a portion of the conduction system are reduced. Through the disclosed technology, the clinical benefits of CSP to patients can be improved by simplifying the process of confirming CSP capture and / or improving ventricular electrical synchrony during CSP. The technology disclosed herein can enable pacing electrodes (which can be lead-based or shell-based electrodes as described in the following examples) to be positioned at pacing sites along the natural conduction system of the heart so as to achieve conduction system capture with high confidence in a simplified, flexible and patient-specific manner. The technology disclosed herein can additionally or alternatively enable the selection and programming of CSP pulse parameters so as to achieve conduction system capture and improved ventricular electrical synchrony with high confidence in a simplified, flexible and patient-specific manner.

[0050] Figure 1 is a conceptual diagram of a medical device system 10 capable of sensing and analyzing cardiac electrical signals and displaying a GUI including a VAT determined by a processor receiving the cardiac electrical signals, according to some examples. Figure 1, a cardiac pacing lead 18 is shown as being advanced within a patient's heart 8 for positioning a pacing electrode 32 at a CSP site within the ventricular septum, such as an LBB pacing site. However, it should be understood that a pacing electrode carried by the lead or by the housing of a leadless pacing device can be positioned at any desired CSP site. The system 10 includes an external device 50, also referred to herein as a "medical device," for receiving and analyzing cardiac electrical signals during a pacing electrode implantation procedure and / or during follow-up monitoring or evaluation. In the example shown, the lead 18 may be coupled to the external device 50 for delivering pacing pulses via the pacing electrode 32, for example, during an implantation procedure. As described below, in other cases, the lead 18 may be coupled to a pacemaker that is generating pacing pulses for delivery via the pacing electrode 32 (and any return electrode), while the external device 50 analyzes the ECG signals and generates data related to the CSP for display in the GUI.

[0051] The external device 50 may be embodied as a programmer or pacing system analyzer used in a hospital, clinic, or physician's office to acquire and analyze cardiac signals. The external device 50 may be a bedside or desktop device or a handheld device, and may be a personal device such as a smart phone, tablet, or other electronic device capable of receiving ECG signals wirelessly or via connected ECG leads. In some examples, the external device 50 is included in a remote patient monitoring system such as the CARELINK ® available from Medtronic, Inc., Dublin, Ireland. TM Monitoring system).

[0052] The external device 50 may include an electrode / lead interface 51 for receiving inputs from the ECG electrodes 40, 42, 44, and 46 and optionally from the implantable pacing and sensing lead 18 via the lead connector 21. The external device 50 may include a processor 52, a memory 53, a display unit 54, a user interface unit 56, a telemetry unit 58, a pulse generator 60, and a power supply 61. The external device 50 may receive ECG signals sensed from a plurality of electrodes, which may be referred to herein as "chest" electrodes and may be skin and / or subcutaneous electrodes in various examples. The term "chest" electrode as used herein refers to an electrode placed in the chest region of the upper torso (e.g., below the neck and above the abdomen or below the sternum and above the lowest rib), and may be placed on the posterior, anterior, or lateral side of the patient.

[0053] In the example shown, three chest electrodes 40, 42, and 44 are positioned to receive three input signals from which processing circuitry of the external device 50 can determine up to three differential unipolar ECG signals and up to three bipolar ECG signals. The obtained ECG signals can be analyzed and / or displayed in a GUI together with data derived from the obtained ECG signals to facilitate the user to easily identify CSP capture and improve ventricular electrical synchrony during CSP. The reference electrode 46 can be positioned anywhere on the patient's body (e.g., along the right lower abdomen or any other location, which can be a chest, abdomen, limb, or lower torso location) to serve as a common ground electrode for each of the raw input signals received from the C1 electrode 40, the C2 electrode 42, and the C3 electrode 44. In some examples, the external device 50 includes an interface 51 for receiving four input signals, including up to three chest electrode input signals and a reference electrode input signal. In general, the techniques disclosed herein provide improvements in displaying and presenting CSP-related data that simplify the process of verifying CSP capture and improve ventricular electrical synchrony by reducing the total number of electrodes placed on the patient and the number of ECG signals received and analyzed by the medical device. The techniques disclosed herein provide improvements in displaying and presenting CSP-related data that simplify the process of verifying CSP capture without requiring a 12-lead ECG system and a high level of electrophysiology expertise.

[0054] In the example shown, the C1 electrode 40 is positioned in a right medial position, which may be located between the second and fifth intercostal spaces on the right side of the sternum. The C1 electrode 40 may be positioned further to the left or right than the position shown, and may be positioned posteriorly or anteriorly. As described below, an ECG signal obtained by the processor 52 of the external device 50 via the C1 electrode 40 positioned as a right chest electrode may represent right ventricular electrical activity. The ECG signal obtained via the C1 electrode 40 positioned as a right chest electrode may be displayed in a GUI for identifying pathological RBB block or pacing-induced RBB block during LBB pacing. The C1 electrode 40 may be positioned to sense a signal having a relatively greater contribution from right ventricular depolarization than from left ventricular depolarization, so that the RBB block type of the QRS waveform can be identified. The C1 electrode 40 may be positioned on the left side of the patient's sternum, but may generally be positioned in a medial or right position, such as above the right ventricle or to the right of the right ventricle.

[0055] As an example, the C2 electrode 42 is shown as being positioned in a left lateral position and may be positioned between the third intercostal space and the seventh intercostal space (or the third rib and the eighth rib). Figure 1The orientation shown is positioned more to the left or right, but is typically positioned to the left of the C1 electrode 40. The C2 electrode 42 can be positioned anteriorly or posteriorly, but is typically positioned to the left of the patient's sternum, such that the ECG signal obtained via the C2 electrode 42 is generally representative of the electrical activity of the left ventricle. The ECG signal obtained via the C2 electrode 42 may have a relatively greater contribution from the depolarization of the left ventricle than from the depolarization of the right ventricle. As described below, in some examples, the VAT may be determined based on the ECG signal obtained via the left chest electrode (e.g., the C2 electrode 42) and displayed on the GUI to facilitate user recognition of CSP capture.

[0056] exist Figure 1 In the example of , C3 electrode 44 is shown in the upper left lateral position. C3 electrode 44 can be used to receive a third single-ended input signal. The third input signal can be used to determine a common mode signal or a center terminal signal during processing of the input signals received from electrodes 40, 42, 44 and 46, and can be used to derive one or more bipolar ECG signals in combination with a unipolar ECG signal obtained from the input signal received from C1 electrode 40 and / or C2 electrode 42. The orientation of C3 electrode 44 can vary between examples and can be any posterior or anterior orientation in the right, left or medial positions. C1 electrode 40, C2 electrode 42 and C3 electrode 44 can be positioned to form a triangle roughly centered on the heart, for example, the triangle can be located above the right ventricle, above the left ventricle, above the ventricular septum, above the ventricular apex, or above the cardiac axis.

[0057] The external device 50 may optionally receive cardiac electrical signals via the pacing lead 18. The pacing lead 18 may be electrically coupled to the external device 50 for providing raw cardiac electrical signals received via the pacing electrode 32 paired with another sensing electrode to obtain an electrocardiogram (EGM) signal that may be displayed in the GUI together with one or more ECG signals obtained from the electrodes 40, 42, 44, and 46 and / or data derived from the one or more ECG signals.

[0058] The processor 52 may be coupled to other components and units of the external device 50, for example, via a data bus 59, for controlling the functions attributed herein to the external device 50. For example, the processor 52 may communicate ECG signals and / or EGM signals and data derived from these signals to the display unit 54 for displaying the data in a GUI. When a pulse generator 60 is included, the processor 52 may control the pulse generator to generate pacing pulses for delivery as CSP pulses. The processor 52 may control the telemetry unit 58 to transmit and receive communication signals.

[0059] The processor 52 executes instructions stored in the memory 53. The processor 52 may include any one or more of the following: a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or an equivalent discrete or analog logic circuit system. In some examples, the processor 52 may include multiple components (such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs) and other discrete or integrated logic circuit systems. The functions attributed to the processor 52 herein may be embodied in software, firmware, hardware, or any combination thereof.

[0060] The memory 53 may include any volatile medium, non-volatile medium, magnetic medium, optical medium, or electrical medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital or analog medium. The memory 53 may be configured to store instructions executed by the processor 52 for obtaining and analyzing ECG signals and generating data in the GUI according to the technology disclosed herein. The memory 53 may store ECG signal features or parameters determined by the processor 52 for generating a display of CSP-related data in the GUI, as described below.

[0061] The display unit 54, which may include a liquid crystal display, a light emitting diode (LED), and / or other visual display components, may generate a display of ECG and / or EGM signals and / or data derived therefrom. The display unit 54 may generate a GUI including various windows, icons, user-selectable menus, etc. to facilitate user interaction with the external device 50. The display unit 54 may be used as an input and / or output device using technology including a liquid crystal display (LCD), a quantum dot display, a dot matrix display, a light emitting diode (LED) display, an organic light emitting diode (OLED) display, a cathode ray tube display, electronic ink, or a monochrome, color, or any other type of display capable of generating tactile, audio, and / or visual output. In some examples, the display unit 54 is a presence-sensitive display that may be used as a user interface device, which operates as one or more input devices and one or more output devices.

[0062] In some examples, the display unit 54 may generate a display of at least one ECG signal annotated with a VAT determined using an ECG signal sensed using a left chest electrode (e.g., C2 electrode 42). The processor 52 may be configured to determine the VAT for a plurality of paced cardiac cycles. As used herein, a "paced cardiac cycle" refers to a cardiac cycle in which a CSP pulse is delivered. However, it should be understood that the delivered CSP pulse may or may not capture any portion of the conduction system. The paced cardiac cycles may include cycles in which the delivered CSP pulse fails to capture any cardiac tissue (no pacing-induced depolarization), captures only the ventricular muscle without capturing a portion of the conduction system, captures a combination of the ventricular muscle and at least a portion of the conduction system, and / or captures at least a portion of the conduction system without capturing the ventricular muscle.

[0063] In other examples, display unit 54 may generate output to the user in another manner, such as via a sound card, a video graphics adapter card, a speaker, one or more USB interfaces, a video and / or audio output interface, or any other type of device capable of generating audio, video, or other output. For example, display unit 54 may include a speaker configured to generate an audible notification in response to detecting a change in VAT by processor 52, the audible notification indicating, for example, a change from non-capture of the conduction system to capture of at least a portion of the conduction system, or vice versa.

[0064] The user interface unit 56 may include a data input or pointing device (such as a mouse, touch screen, keypad, etc.) to enable a user to interact with the external device 50 and the GUI displayed on the display unit 54, for example to initiate and terminate an implantation session, adjust the settings of the display unit 54, enter programmable control parameters to be programmed into a pacemaker coupled to the CSP lead 18, or make other user requests. The telemetry unit 58 includes a transceiver and an antenna configured for bidirectional communication with a telemetry circuit included in the implantable pacemaker, which can be coupled to the CSP lead 18 after the pacing electrode 32 is deployed to an acceptable CSP site. The telemetry unit 58 is configured to operate in conjunction with the processor 52 for sending and receiving data related to pacemaker function via a wireless communication link with the implantable pacemaker.

[0065] In some examples, the external device 50 may include a pulse generator 60 for generating and delivering pacing pulses via the lead 18, for example, during an implantation procedure. The post-pacing ECG signal may be analyzed to determine when a VAT change indicating an improvement in electrical synchrony and an acceptable CSP site is detected. In some examples, the external device 50 may control the pulse generator 60 to generate pacing pulses to perform a capture test during implantation of the CSP lead 18. The lead 18 may be coupled to the external device 50 via the lead connector 21 and the interface 51. The pulse generator 60 may include one or more holding capacitors charged to a pacing pulse voltage amplitude by a power supply 61 of the external device 50. When the holding capacitor is discharged for a selected pacing pulse width, the holding capacitor may be coupled to an output capacitor via a switching circuit system to deliver a pacing pulse via the pacing electrode 32 (and a return anode electrode). In other examples, the pulse generator 60 may be a separate device (such as a pacing system analyzer or a temporary external pacemaker) that may be coupled to the lead 18 for delivering CSP pulses.

[0066] The external device 50 includes a power source 61 coupled to various units of the external device 50 for providing power as needed to the circuits and components of the external device 50. The power source 61 may include one or more rechargeable or non-rechargeable batteries, or may be connected to an external power source, such as plugged into a power outlet.

[0067] In some examples, a catheter 16 or other delivery tool for implanting a lead 18 may include a return electrode 17 that is used in combination with a pacing electrode 32 to deliver pacing pulses and / or sense cardiac signals during implantation of the pacing electrode 32 at the CSP site. The lead 18 may include one or more ring electrodes that may be selected for a pacing electrode vector, such as Figure 2 As shown. However, in some cases, the return electrode carried along the lead 18, proximal to the pacing electrode 32, may be insulated within the body of the catheter 16 or another delivery tool, so that the return electrode is not available for sensing and / or pacing during the implantation procedure. In this case, the catheter 16 may carry one or more electrodes, such as a ring return electrode 17, to serve as an anode electrode that is paired with the pacing electrode 32 before the lead connector 20 is connected to the implantable pacemaker. In other examples, another skin or subcutaneous electrode may be provided and coupled to the external device 50 via the interface 51 to serve as a return anode in combination with the pacing electrode 32 to test and evaluate the CSP during the implantation procedure.

[0068] Figure 21 is a conceptual diagram of a CSP lead 18 coupled to an implantable medical device (IMD) 14 capable of pacing a patient's heart 8 and sensing cardiac electrical signals via lead 18. The pacing electrode 32 of lead 18 can be positioned at an acceptable CSP site, which can be confirmed at least in part based on VAT data displayed in a GUI by an external device 50 (as further described below). IMD 14 is shown as a dual-chamber device configured to receive a right atrial lead 16, which is positioned in the right atrium (RA) to deliver atrial pacing pulses and sense atrial electrical signals via electrodes 20 and 22. IMD 14 can be configured to sense intrinsic atrial P waves, and deliver atrial pacing pulses in the absence of sensed P waves. IMD 14 can be configured to deliver atrial synchronized ventricular pacing by setting an AV delay in response to each sensed P wave or delivered atrial pacing pulse, and deliver CSP pulses via lead 18 to synchronously pace the ventricles and atria upon expiration of the AV delay.

[0069] The CSP lead 18 may be advanced transvenously into the RV via the RA to position the pacing electrode 32 within the ventricular septum 19. The pacing electrode 32 may be referred to as a "tip electrode" because it is carried by the CSP lead 18 at the distal lead tip. When the pacing electrode 32 is advanced relatively upward within the ventricular septum 19, the pacing electrode 32 may be positioned along the lower portion of the His bundle for delivery of CSP pulses. In other examples, the pacing electrode 32 may be advanced within the ventricular septum 19 near a bundle branch of the His-Purkinje system (e.g., at an LBB pacing site in the LBB region or at a right bundle branch RBB pacing site in the RBB region) for delivery of CSP pulses.

[0070] The pacing electrode 32 may be selected as a pacing cathode electrode, used in combination with the ring electrode 34 as a return anode electrode for CSP. In some cases, the pacing pulse amplitude and pulse width may be selected to achieve cathode capture at the cathode electrode for capturing at least a portion of one bundle branch. In other cases, the pacing pulse amplitude and pulse width may be selected to achieve cathode and anode capture, which may capture both the LBB and the RBB concurrently (by the same pacing pulse) to provide dual or bilateral bundle branch (BB) pacing using a single bipolar electrode pair. In other examples, the pacing electrode 32 or the ring electrode 34 may be selected as a cathode electrode paired with the housing 15 in a unipolar pacing electrode vector. Unipolar pacing may capture at least a portion of a single BB. However, in some cases, when a unipolar pacing pulse directly captures one bundle branch, unipolar pacing may capture both the RBB and the LBB, while the virtual current or disconnected excitation generated by the pacing electrode may excite another bundle branch, thereby potentially causing unipolar bilateral BB pacing while capturing both the LBB and the RBB.

[0071] Although the CSP lead 18 is shown as carrying a pacing and sensing electrode pair (i.e., a pacing electrode 32 and a ring electrode 34), it should be understood that in other examples, the CSP lead 18 may include multiple pacing and sensing electrodes along its distal portion to provide one or more selectable bipolar pacing electrode vectors and / or one or more unipolar pacing electrode vectors (e.g., in conjunction with the housing 15) for delivering CSP pulses and sensing ventricular electrical signals.

[0072] The CSP lead pacing 18 may also include one or more cardioversion / defibrillation (CV / DF) electrodes 35 for delivering relatively high voltage shock therapy. The CV / DF electrodes typically have a high surface area and may be elongated coil electrodes, as exemplified by the coil electrode 35 on the CSP lead 18. In addition to delivering relatively low voltage atrial and CSP pulses, the IMD 14 may also be configured as an implantable cardioverter-defibrillator (ICD) capable of delivering high voltage shock therapy to terminate ventricular tachycardia or fibrillation. The coil electrode 35 may also be used in a sensing electrode vector (e.g., in conjunction with either of the pacing electrode 32 or the ring electrode 34) to sense ventricular EGM signals, which may be transmitted to the external device 50 via the communication link 62 for display by the display unit 54 in the GUI. Other examples of pacing lead configurations for delivering CSP that may be used in conjunction with the techniques described herein are generally disclosed in U.S. Publication No. 2022 / 0023640 (Zhou et al.) and U.S. Patent No. 11 / 207,529 (Zhou et al.), both of which are incorporated herein by reference in their entirety.

[0073] IMD 14 includes housing 15 that encloses electronic circuitry configured to perform cardiac signal sensing and therapy delivery functions attributed to IMD 14. Figure 6 An example of circuitry that may be included in IMD 14 is described. IMD 14 includes a connector block 12, sometimes referred to as a "header," having a proximal lead connector ( 12 ) for receiving each of the corresponding leads 16 and 18 coupled to IMD 14. Figure 2 14). Each of leads 16 and 18 includes an insulated electrical conductor that extends through one or more lumens within the elongated electrically insulated lead body of leads 16 and 18. Each electrical conductor extends from a respective electrode 20, 22, 32, 34, and 35 to a proximal lead connector of a corresponding lead 16 or 18 to provide an electrical connection to an electrical contact within connector block 12. Electrical connection of electrodes 20, 22, 32, 34, and 35 to the internal electronic circuitry of IMD 14 is provided by an electrical feedthrough in connector block 12 that passes through hermetically sealed housing 15 of IMD 14.

[0074] In this manner, the insulated electrical conductors extending through the leads 16 and 18 carry electrical signals from the therapy delivery circuitry within the housing 15 to the electrodes 20, 22, 32, 34, and 35 for delivering electrical stimulation therapy, performing impedance measurements, inducing tachyarrhythmias during device testing, and the like. The insulated electrical conductors may carry cardiac electrical signals of the heart 8 from the electrodes 20, 22, 32, 34, and 35 to the sensing circuitry within the housing 15 for obtaining atrial and ventricular EGM signals. As described above, the IMD 14 may communicate with the external device 50 via wireless telemetry. The external device 50 may receive the EGM signals, the delivered atrial pacing pulse marker signals, and / or the delivered CSP pulse marker signals, which are transmitted by the IMD 14 for analysis of the ECG signals obtained by the external device 50 and / or for display in the GUI for observation and inspection by a clinician or other user.

[0075] Figure 3 is a conceptual diagram of an IMD 14 coupled to a CSP lead 18 that is advanced to an alternative location within the heart 8 to deliver CSP pulses and sense cardiac electrical signals. In this example, a distal portion of the CSP lead 18 is advanced within the RA from a right atrial approach for sensing ventricular electrical signals and delivering CSP pulses at or near the His bundle. Figure 3 In some examples, the pacing electrode 32 of the CSP lead 18 can be advanced into cardiac tissue in the His bundle region, such as between the His bundle and the coronary sinus and adjacent to the tricuspid valve. In some examples, the target entry site of the pacing electrode 32 can correspond to or be located within the Koch triangle for achieving CSP at the His bundle pacing site. The pacing electrode 32 can be paired with a return anode ring electrode 34 for delivering CSP pulses and for sensing raw cardiac electrical signals, which can be processed for obtaining ventricular EGM signals.

[0076] In some examples, CSP may be delivered in combination with LV myocardial pacing, which may be delivered via a left ventricular (LV) lead 47 for further improving electrical and mechanical synchrony of the RV and LV, for example, during cardiac resynchronization therapy (CRT). LV lead 47 may be advanced into the RA, through the coronary sinus ostium and into the cardiac veins of the left ventricle to position electrodes 48a, 48b, 48c, and 48d (collectively referred to as "LV electrodes 48") along the LV myocardium to sense ventricular electrical signals and pace the LV myocardium. LV lead 47 is shown as a quadripolar lead carrying four electrodes 48a to 48d, which may be selected from a variety of bipolar pacing electrodes for pacing the LV myocardial tissue and sensing LV signals. One of the LV electrodes 48 may be selected to be combined with the IMD housing 15 for delivering unipolar LV myocardial pacing and / or for sensing ventricular EGM signals that may be transmitted to an external device 50 via a communication link 62 in some cases.

[0077] When CSP lead 18 is positioned for delivery of CSP, CSP can be combined with ventricular myocardial pacing (using LV lead 47) to correct LV conduction delays and achieve electrical and mechanical synchrony of the ventricles. Thus, in some examples, IMD 14 can control the combination of CSP pulse delivery and LV myocardial pacing pulse delivery at a specific time interval, which may include AV delay and / or ventricle-to-ventricle (VV) delay. AV delay can control the timing of CSP pulses and / or LV myocardial pacing pulses relative to atrial events (e.g., sensed P waves or delivered atrial pacing pulses). In some examples, VV delay can control the timing between CSP pulses delivered via CSP lead 18 and LV myocardial pacing pulses delivered via LV lead 47.

[0078] It should be understood that LV lead 47 is optional. In some examples, IMD 14 is coupled only to CSP lead 18 advanced into the RA or RV for positioning pacing electrode 32 at the CSP site for delivering CSP and sensing ventricular EGM signals. In other examples, such as Figure 2 RA lead 16 is shown implanted in combination with CSP lead 18 for delivery of CSP in a dual chamber sensing and pacing system. External device 50 may receive one or more EGM signals from IMD 14 sensed using any available EGM sensing electrode vectors.

[0079] Figure 4is a conceptual diagram of a leadless pacemaker 114 positioned within the RA to provide CSP according to another example. The pacemaker 114 may include a distal tip electrode 102 extending away from a distal end 112 of a pacemaker housing 105, which may also be referred to as a "pacing electrode" or "CSP electrode." The pacemaker 114 is shown as being implanted in the RA of a patient's heart 8 to position the distal tip electrode 102 to deliver CSP pulses in the region of the His bundle. For example, the distal tip electrode 102 may be inserted at the lower end of the atrial septum, below the AV node, and near the tricuspid annulus to position the tip electrode 102 in, along, or near the His bundle. The distal tip electrode 102 may be a spiral electrode that provides fixation to anchor the pacemaker 114 at the implantation site. In other examples, the pacemaker 114 may include a fixation member including one or more tines, hooks, barbs, spirals, or other fixation members that anchor the distal end of the pacemaker 114 at the implantation site. A portion of the distal tip electrode 102 may be electrically insulated such that only the distal-most end of the tip electrode 102 (furthest from the housing distal end 112) is exposed to provide targeted pacing at the CSP site.

[0080] One or more housing-based electrodes 104 and 106 may be carried on a surface of a housing 105 of a pacemaker 114. The electrodes 104 and 106 are shown as ring electrodes that surround a longitudinal sidewall 107 of the pacemaker housing 105. The longitudinal sidewall 107 extends from a distal end 112 to a proximal end 110 of the housing 105. In other examples, a return anode electrode for sensing and pacing may be positioned on the housing proximal end 110. Pacing of the conduction system may be achieved using the distal tip electrode 102 as a cathode electrode and using either of the housing-based electrodes 104 and 106 as a return anode.

[0081] The cardiac electrical signal may be sensed by the pacemaker 114 using a sensing electrode pair selected from the electrodes 102, 104, and 106. For example, the cardiac electrical signal may be sensed using the distal tip electrode 102 and the distal housing-based electrode 104 or the proximal housing-based electrode 106. A second cardiac electrical signal may be sensed using the electrodes 104 and 106. The EGM signal sensed by the pacemaker 114 may be transmitted to the external device 50 via the communication link 62 for display in the GUI.

[0082] In some examples, an atrial P wave may be sensed from signals received via electrodes 104 and 106, and / or an atrial pacing pulse may be delivered via electrodes 104 and 106. An atrial synchronized CSP pulse may be delivered via electrodes 102 and 104 with an AV delay after the sensed atrial P wave and / or the delivered atrial pacing pulse.

[0083] Figure 5 yes Figure 4 1 is a conceptual diagram of a leadless pacemaker 114 shown implanted in an alternative location for CSP. In some examples, the pacemaker 114 can be implanted within the RV along the interventricular septum 19 for providing CSP. The techniques disclosed herein can be used in conjunction with a leadless pacemaker, such as the pacemaker 114, having a pacing electrode 102 coupled to and extending directly from the pacemaker housing 105, without the need for invasive medical leads coupled to the pacemaker 114 for carrying pacing and sensing electrodes.

[0084] In this example, a pacemaker 114 may be positioned within the RV for advancing a pacing tip electrode 102 extending from a distal end 112 of a pacemaker housing 105 into the ventricular septum 19 for delivering a CSP, for example, in the region of the lower portion of the His bundle or along one or both of the RBB and LBB (depending on the relative positioning of the distal tip electrode 102). The distal tip electrode 102 is shown as a "screw-in" spiral electrode, but may be configured as other types of tissue-piercing electrodes capable of being advanced within septal tissue. A proximal portion of the distal tip electrode 102 may be electrically insulated, for example, with a coating, such that only a distal portion of the tip electrode 102 farthest from the pacemaker housing distal end 112 is exposed to provide targeted pacing at a tissue site including the His bundle, the LBB, and the RBB.

[0085] In other examples, the distal tip electrode 102 can be formed to have a straight shaft having a distal active electrode portion or other type of electrode, which can be a tissue-piercing electrode that can be advanced through the ventricular septum 19 to deliver a CSP in the left portion of the septum 19 in the region of the LBB, for example. In some examples, the pacemaker 114 can include a fixation member comprising one or more tines, hooks, barbs, spirals, or other fixation members that anchor the distal end 112 of the pacemaker 114 at the implantation site and which can not serve as an electrode. Examples of leadless intracardiac pacemakers that can be configured to deliver cardiac pacing pulses to a conduction system that can be used in conjunction with the techniques described herein are generally disclosed in U.S. Patent No. 11,207,529 (Zhou) and U.S. Publication No. 2019 / 0083800 (Yang et al.), incorporated herein by reference in their entirety, which are incorporated herein by reference.

[0086] The pacemaker 114 may include a distal housing-based ring electrode 104 along or near a distal end 112 of the pacemaker housing 105. In an example, the distal housing-based ring electrode 104 may be selected as a return anode electrode for use with the distal tip electrode 102 for bipolar pacing of the LBB and / or RBB near the distal tip electrode 102. Simultaneous bipolar bilateral BB pacing of both the RBB and the LBB may be achieved by cathodic capture of the LBB at the distal tip electrode 102 and anodal capture of the RBB by the distal ring electrode 104. The polarity of the distal tip electrode 102 and the distal ring electrode 104 may be reversed to achieve cathodic capture of the RBB and anodal capture of the LBB in some examples. The distal ring electrode 104 is shown as a ring electrode surrounding the distal portion of the shell 105, but can alternatively be a distal shell-based electrode in the form of a button electrode, a hemispherical electrode, a segmented electrode, etc. and can be along the surface of the distal end 112 of the shell 105 and / or along the longitudinal side wall 107.

[0087] In the example shown, a proximal housing-based ring electrode 106 that may surround all or part of a longitudinal sidewall 107 of the housing 105 may be provided as a return anode electrode. In other examples, a return anode electrode for sensing and pacing may be positioned on the housing proximal end 110 and may be a button, ring, or other type of electrode. CSP in the region of the LBB may be achieved using the tip electrode 102 as a cathode electrode and the proximal ring electrode 106 as a return anode. CSP in the region of the RBB and / or myocardial tissue of the ventricular septum 19 may be achieved using the distal ring electrode 104 as a cathode electrode and the proximal ring electrode 106 as a return anode. In this way, bilateral or dual bundle branch pacing of the conduction system may be achieved using two different bipolar pacing electrode vectors carried by the housing 105.

[0088] The cardiac electrical signals generated by heart 8 may be sensed by pacemaker 114 using electrodes 102, electrodes 104, and / or electrodes 106. The cardiac electrical signals received via electrodes 102 and 104, electrodes 104 and 106, and / or electrodes 102 and 106 may be sensed by pacemaker 114 and processed by processing circuitry of IMD 14, for example, and / or wirelessly transmitted to external device 50, for example as EGM signals, via communication link 62. These EGM signals may then be displayed and / or further processed and analyzed by processor 52 of external device 50 to provide a user with a visual representation of the sensed EGM signals and / or CSP-related data.

[0089] Figures 1 to 5The examples of the present invention present various lead and / or electrode configurations that may be implemented for delivering CSPs in a medical device system configured to perform the techniques disclosed herein for analyzing cardiac electrical signals and generating a GUI for presenting data to a clinician or other user to confirm the CSP site of a pacing electrode and / or to confirm CSP capture. The various lead and electrode configurations described and shown in the accompanying drawings are intended to be illustrative in nature. It should be understood that Figures 1 to 5 The leads and electrodes illustrated in the examples may be implanted in different combinations and / or other locations than those shown, and some leads and / or electrodes may be omitted, or additional leads and / or electrodes may be provided in a medical device system configured to deliver and monitor CSP. In some examples, a leadless IMD (e.g., pacemaker 114) may be implanted in a patient in combination with another implanted IMD (e.g., an IMD connected to an RA lead for pacing and sensing in the right atrium and / or an ICD coupled to extracardiac leads for providing tachyarrhythmia detection and therapy delivery) for CSP. Various lead-based and leadless IMD configurations are contemplated for sensing cardiac electrical signals and delivering CSP pulses, which may be used in conjunction with the techniques disclosed herein for analyzing ECG signals and presenting CSP-related data to a user in a GUI displayed by an external device 50.

[0090] Figure 6 is a schematic diagram of circuitry that may be packaged within an IMD configured to sense cardiac electrical signals and to perform CSP. Figure 6 The block diagram of FIG. 1 is described with reference to IMD 14, which is coupled to electrodes 20 and 22 carried by RA lead 16 and electrodes 32, 34 and 35 carried by CSP lead 18, such as, for example, as an illustrative example. Figure 2 However, it should be understood that Figure 6 The functionality of the various circuits and components shown in for sensing cardiac signals and delivering CSPs may be implemented in conjunction with other lead and electrode configurations, including Figure 4 and Figure 5 A leadless pacemaker 114 or other medical device configured to deliver CSP pulses and sense cardiac electrical signals.

[0091] Shell 15 Figure 6, which are represented as electrodes for cardiac electrical signal sensing and, in some examples, for delivering unipolar pacing pulses. When the IMD 14 is implemented as an ICD, the housing 15 can be used as an active can electrode for delivering CV / DF shock pulses. The electronic circuit system encapsulated in the housing 15 includes software, firmware, and hardware that work together to monitor cardiac electrical signals, determine when a pacing pulse is needed, and deliver pacing electrical pulses to the patient's heart as needed according to the programmed pacing mode and pacing pulse control parameters. The electronic circuit system may include a control circuit 80, a memory 82, a therapy delivery circuit 84, a cardiac electrical signal sensing circuit 86, a telemetry circuit 88, and a power supply 98.

[0092] Power supply 98 provides power as needed to the circuitry of IMD 14, including each of components 80, 82, 84, 86, and 88. Power supply 98 may include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. Connections between power supply 98 and each of the other components 80, 82, 84, 86, and 88 will be Figure 6 84, but are not shown for clarity. For example, power supply 98 may be coupled to one or more charging circuits included in therapy delivery circuit 84 to provide the power required to charge a holding capacitor included in therapy delivery circuit 84, which is discharged at the appropriate time to deliver a pacing pulse under the control of control circuit 80. Power supply 98 is also optionally coupled to components of sensing circuit 86 for sensing cardiac electrical signals, such as sense amplifiers, analog-to-digital converters, switching circuit systems, etc. Power supply 98 can provide power to various components and circuits of telemetry circuit 88 and memory 82 as needed, which can be under the control of control circuit 80.

[0093] Figure 6 The circuits shown are representative of the functionality included in the IMD 14 and may include any discrete and / or integrated electronic circuit components that implement analog and / or digital circuits capable of producing the functions attributed herein to the IMD 14 (or pacemaker 114). The various components may include application specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated, or groups) and memories that execute one or more software or firmware programs, combinational logic circuits, state machines, or other suitable components or combinations of components that provide the described functionality. In view of the disclosure herein, it is within the capabilities of those skilled in the art to provide software, hardware, and / or firmware to implement the described functionality in the context of any modern cardiac medical device system.

[0094] The control circuit 80 communicates with the therapy delivery circuit 84 and the sensing circuit 86, for example, via a data bus, to cooperatively sense cardiac electrical signals and control the delivery of cardiac electrical stimulation therapy in response to sensed cardiac event signals (e.g., a P wave accompanying atrial depolarization and an R wave accompanying ventricular depolarization, or the absence thereof). Available electrodes are electrically coupled to the therapy delivery circuit 84 for delivering electrical stimulation pulses and / or the sensing circuit 86 for sensing cardiac electrical signals generated by the heart. The sensed cardiac electrical signals may include intrinsic signals generated by the heart in the absence of a pacing pulse that captures the heart (such as an intrinsic R wave and an intrinsic R wave), as well as induced response signals following a delivered pacing pulse of sufficient energy to cause capture of cardiac tissue.

[0095] The sensing circuit 86 may include one or more sensing channels for receiving raw cardiac electrical signals from one or more sensing electrode vectors. For example, atrial signals may be sensed using right atrial lead electrodes 20 and 22 coupled to atrial sensing (A sensing) channel 87. Ventricular signals may be sensed through a ventricular sensing (V sensing) channel 89 using electrodes 32, 34, and / or 35 carried by the CSP lead 18. In some examples, the V sensing channel 89 may include multiple ventricular sensing channels for receiving raw signals from multiple sensing electrode vectors, which may include at least one electrode in or near the ventricular chamber. For example, the V sensing channel 89 may include a near-field sensing channel for receiving raw near-field signals using electrodes 32 and 34 of a CSP lead pacing 18 in a bipolar sensing electrode pair. The V sensing channel 89 may include a far-field or unipolar sensing channel for receiving raw far-field signals. For example, a second electrode vector may be used to receive raw far-field signals, the second electrode vector having electrodes that are farther apart than the electrodes of the near-field sensing electrode vector. For example, far-field signals may be sensed using pacing electrodes 32 or ring electrodes 34 of CSP lead 18 paired with IMD housing 15. In some examples, V sensing channel 89 may receive raw far-field signals sensed using pacing electrodes 32 or ring electrodes 34 paired with coil electrodes 35. In other examples, far-field signals may be sensed using coil electrodes 35 paired with IMD housing 15.

[0096] The sensing circuit 86 may include switching circuitry for selectively coupling sensing electrode pairs among the available electrodes to corresponding sensing channels among the A sensing channels 87 or the V sensing channels 89. The switching circuitry may include a switch array, a switch matrix, a multiplexer, or any other type of switching device suitable for selectively coupling components of the sensing circuit 86 to selected electrodes.

[0097] Each of the sensing channels 87 and 89 of the sensing circuit 86 may include an input filter, a preamplifier, an analog-to-digital converter (ADC), and a bandpass filter for receiving raw cardiac electrical signals from a corresponding pair of sensing electrodes to generate a multi-bit digital cardiac electrical signal, which may be referred to as an "intracardiac EGM" signal when the raw signal is sensed using at least one electrode within a cardiac chamber. The multi-bit EGM signal may be passed from the sensing circuit 86 to the control circuit 80 for processing and analysis, and / or for transmission to an external device 50 (e.g., Figure 1 ) for processing and analysis and / or display on the display unit 54.

[0098] Each sensing channel 87 and 89 may include cardiac event detection circuitry that may include one or more sense amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components for detecting cardiac electrical events. For example, an atrial event detector may be included in the A sensing channel 87 for sensing an intrinsic P wave associated with intrinsic atrial depolarization using one or both of electrodes 20 and 22 carried by the right atrial lead 16. A ventricular event detector may be included in the V sensing channel 89 for sensing an intrinsic R wave associated with intrinsic ventricular depolarization using electrodes 32 and 34 carried by the CSP lead 18.

[0099] The cardiac event sensing thresholds (such as, the P wave sensing threshold and / or the R wave sensing threshold) can be automatically adjusted by the sensing circuit 86 under the control of the control circuit 80, for example, based on a timing period and a sensing threshold determined by the control circuit 80, stored in the memory 82, and / or controlled by the hardware, firmware and / or software of the control circuit 80 and / or the sensing circuit 86. For example, the R wave sensing threshold can be controlled to start at a starting threshold voltage after the post-ventricular blanking period and then decrease according to the decay curve until a minimum sensing threshold is reached. The minimum R wave sensing threshold can be set to a programmed sensitivity of the R wave detection circuit system. The sensitivity, which is programmed to a voltage level, typically in millivolts, is the minimum voltage level above which the cardiac event detection circuit system of the corresponding A sensing channel 87 or V sensing channel 89 can sense a P wave or an R wave.

[0100] Upon detecting a cardiac electrical event based on a sensing threshold crossing, the sensing circuit 86 may generate a sensed event signal that is communicated to the control circuit 80. For example, an atrial event detector may generate an atrial sensed event signal in response to a P wave sensing threshold crossing. A ventricular event detector may generate a ventricular sensed event signal in response to an R wave sensing threshold crossing. The sensed event signal may be used by the control circuit 80 to initiate a pacing escape interval timer that controls a base time interval for scheduling cardiac pacing pulses (e.g., atrial pacing pulses) and CSP pulses.

[0101] The control circuit 80 may include various timers or counters for counting down the AV delay, VV delay, atrial pacing lower rate interval, ventricular pacing lower rate interval, or other pacing escape intervals according to the pacing mode and pacing control parameters. The sensed event signal may trigger or inhibit a pacing pulse, depending on the specific programmed pacing mode. For example, a P wave sensed event signal received from the sensing circuit 86 may cause the control circuit 80 to inhibit a scheduled atrial pacing pulse and schedule a CSP pulse at the AV delay. If the AV delay expires before the control circuit 80 receives an R wave sensed event signal from the sensing circuit 86, the therapy delivery circuit 84 may generate and deliver a CSP pulse at the AV delay after the sensed P wave, and in this manner deliver atrial synchronized ventricular pacing. If an R wave sensed event signal is received from the sensing circuit 86 before the AV delay expires, the scheduled CSP pulse may be inhibited. The AV delay controls the amount of time between an atrial event (paced or sensed) and a CSP pulse to promote electrical and mechanical synchrony of the heart chambers.

[0102] In other cases, a ventricular pacing lower rate interval (LRI) may be set by control circuit 80 to schedule a CSP pulse after a delivered CSP pulse or a sensed R wave. The LRI may correspond to a programmed ventricular lower rate, or may be adjusted by control circuit 80 to a temporary LRI to adjust the ventricular pacing interval to a lower rate, such as by an accelerometer signal or other patient activity sensor included in IMD 14 ( Figure 6 The control circuit 80 may be configured to control the therapy delivery circuit 84 to deliver CSP pulses according to various pacing modes and pacing therapies, which may include bradycardia pacing, post-shock pacing, anti-tachycardia pacing (ATP), cardiac resynchronization therapy (CRT), rate-responsive pacing, and the like.

[0103] The therapy delivery circuit 84 may include charging circuitry, one or more charge storage devices (such as one or more holding capacitors), an output capacitor, and a switch circuitry that controls when the holding capacitor is charged and discharged across the output capacitor to deliver pacing pulses to a selected pacing electrode vector coupled to the therapy delivery circuit 84. The therapy delivery circuit 84 may include one or more pacing channels. In the example of the IMD 14, the therapy delivery circuit 84 may include an atrial pacing channel and a ventricular pacing channel, each channel including one or more holding capacitors, one or more switches, and an output capacitor for generating pacing pulses delivered by a corresponding RA lead 16 (e.g., via electrodes 20 and 22) or CSP lead 18 (e.g., via electrodes 32 and 34). In other examples, the atrial and ventricular pacing pulses may be generated and delivered by a shared pulse generation circuitry.

[0104] Charging the holding capacitor to the programmed pacing voltage amplitude and discharging the capacitor for the programmed pacing pulse width may be performed by therapy delivery circuit 84 in accordance with control signals received from control circuit 80. For example, a pacing timing circuit included in control circuit 80 may include a programmable digital counter set by a microprocessor of control circuit 80 to control, for example, various single-chamber and / or dual-chamber pacing modes, when LV lead 47 ( Figure 3 ) is connected to IMD 14 for delivery of CRT and / or for delivery of ATP sequence when the multi-chamber pacing mode is associated. The microprocessor of control circuit 80 may also set the amplitude, pulse width, polarity or other characteristics of the cardiac pacing pulses that may be based on programmed values ​​stored in memory 82.

[0105] The IMD 14 may be configured to detect non-sinus tachycardia and deliver ATP. When the IMD 14 is configured as an ICD for detecting tachycardia and delivering CV / DF shocks, in addition to the low-voltage therapy circuit system for generating low-voltage pacing pulses, the therapy delivery circuit 84 may also include a high-voltage therapy delivery circuit system for generating high-voltage shock pulses. In response to detecting ventricular tachycardia or fibrillation, the control circuit 80 may control the therapy delivery circuit 84 to deliver CV / DF shocks. The high-voltage therapy circuit system may include a high-voltage capacitor and a high-voltage charging circuit system for generating and delivering CV / DF shock pulses using an elongated coil electrode (e.g., coil electrode 35) and / or housing 15 carried by one or more leads coupled to the IMD 14.

[0106] Control parameters used by control circuit 80 to sense cardiac event signals (e.g., P and R waves) and control pacing therapy delivery may be programmed into memory 82 via telemetry circuit 88. Telemetry circuit 88 includes a communication device for communicating with an external device 50 (e.g., Figure 1 ) for communicating with the external device 50. Under the control of the control circuit 80, the telemetry circuit 88 can receive downlink telemetry from the external device 50 and send uplink telemetry to the external device. In some cases, the telemetry circuit 88 can be used to transmit communication signals to another medical device implanted in the patient's body and receive communication signals from another medical device implanted in the patient's body. The telemetry circuit 88 can transmit EGM signals, pacing pulse timing markers, atrial and ventricular sensing event signal markers, and other sensing and pacing related data for real-time reception by the external device 50 and / or from stored EGM signal fragments, and these EGM signal events can be displayed by the external device 50.

[0107] Figure 7 is a flow chart 150 of a method for processing and analyzing ECG signals and generating a GUI for display by an external device 50 according to some examples. Figure 1In the external device 50 shown, at box 152, the external device processor 52 receives input signals from multiple electrodes positioned on the patient. The external device processor 52 may be configured to receive input signals from each of four or fewer electrodes (e.g., consisting of three or fewer chest electrodes and a reference electrode). In other examples, the external device processor 52 may be configured to receive and analyze input signals consisting of five or fewer input signals received from each of five or fewer electrodes consisting of four or fewer chest electrodes and a reference electrode. In other examples, the external device processor 52 may be configured to receive input signals from at least two chest electrodes (e.g., a right chest electrode and a left chest electrode) and a reference electrode. In other examples, the external device processor 52 may be configured to receive input signals from multiple chest electrodes, the multiple chest electrodes including two, three, four or more chest electrodes and a reference electrode, wherein the multiple chest electrodes include at least one right chest electrode and at least one left chest electrode, and may be composed of four or fewer electrodes, five or fewer electrodes, six or fewer electrodes, seven or fewer electrodes, eight or fewer electrodes, or nine or fewer electrodes. The right chest electrode may be positioned medially (e.g., above the sternum or spine), or to the right of the sternum or spine, for sensing cardiac electrical signals representative of or associated with right ventricular electrical activity. The left chest electrode may be positioned above the sternum or spine, but may typically be positioned to the left of the sternum or spine, for sensing cardiac electrical signals representative of or associated with left ventricular electrical activity. Each input signal may be received as a single-ended input signal.

[0108] The 12-lead ECG can be manually analyzed by an electrophysiologist or other expert to observe and identify conduction system abnormalities and improvements in conduction system abnormalities. A 12-lead ECG typically requires 10 electrodes, including limb electrodes and precordial electrodes, which may be time-consuming to position to obtain high-quality ECG signals. The observation and analysis of a 12-lead ECG requires considerable expertise and time to identify the capture of the conduction system and the improvement of ventricular electrical synchrony. Some clinics or other medical facilities that may be treating or following up patients implanted with an IMD or pacemaker for delivering CSP may not have the equipment or personnel to perform a 12-lead ECG study to monitor CSP and make any necessary adjustments to facilitate CSP capture and improve ventricular electrical synchrony. The technology disclosed herein enables a user to connect fewer than ten electrodes required for a 12-lead ECG study to an external device 50, and presents CSP-related data determined from the obtained ECG signal in a GUI, which simplifies the process of verifying CSP capture and ventricular electrical synchrony improvement in a time-efficient manner for the user.

[0109] At block 154, the external device processor 52 (hereinafter referred to as "processor" 52) may obtain one or more ECG signals from the received input signal by determining one or more differential ECG signals from the input signal. Figure 8 As described, the processor 52 may determine a common-mode voltage signal that may represent a center terminal of a chest electrode. The processor 52 may determine a unipolar left chest ECG signal using an input signal and a common-mode voltage signal (also referred to herein as a "center terminal signal") received via the left chest electrode. The processor 52 may determine a unipolar right chest ECG signal using an input signal and a common-mode voltage signal received via the right chest electrode. The processor 52 may determine a bipolar ECG signal by determining the difference between two unipolar ECG signals. In some examples, the processor 52 may determine a plurality of bipolar ECG signals, wherein each bipolar ECG signal may be calculated as the difference between two different unipolar ECG signals.

[0110] At box 156, the processor 52 determines VAT based on at least one of the differential ECG signals. The processor 52 may determine VAT using a unipolar left chest ECG signal. In one example, the processor 52 determines VAT based on a unipolar left chest ECG signal by determining a time interval from a delivered CSP pulse to a maximum peak amplitude of the unipolar left chest ECG signal, which may be a rectified or non-rectified signal. In another example, the processor 52 determines VAT using the unipolar left chest ECG signal by calculating a bipolar ECG signal using the unipolar left chest ECG signal and a second unipolar ECG signal determined based on an input signal. VAT may be determined by the processor 52 by determining a time interval from a delivered CSP pulse to a maximum peak amplitude of a bipolar ECG signal, which is calculated using an input signal received from a left chest electrode. As an example, the left chest electrode may be located between the sternum and the spine on the left side of the patient, between the third intercostal space and the eighth intercostal space.

[0111] At box 156, VAT (referred to as "excitation time" in flowchart 150 and other figures presented herein) may be determined by the processor 52 from at least one unipolar or bipolar ECG signal using input signals received from the left chest electrode. VAT may be determined for each of a plurality of cardiac cycles, for example, from a respective maximum peak amplitude of the ECG signal from each of a plurality of delivered CSP pulses. VAT may be determined beat by beat (e.g., pulse by pulse in a series of a plurality of CSP pulses) or for non-continuous cardiac cycles. At box 158, the processor 52, in cooperation with the display unit 54 of the external device 50, generates a display of the determined VAT in a GUI.

[0112] As described below and as shown in the accompanying drawings, the processor 52 and the display unit 54 can cooperate to generate a display of at least one ECG signal determined according to an input signal, which can be annotated or shown in combination with the determined VAT on a beat-by-beat basis. In some examples, the beat-by-beat display of at least one ECG signal and the associated VAT can be displayed in real time as a scrolling ECG signal or as a previously stored ECG fragment after processing and analysis and data collection. The scrolling ECG signal and the associated VAT can be frozen on the display unit 54 by the user interacting with the GUI (such as via a touch screen or other pointing device of the user interface 56 for user inspection).

[0113] In other examples, at least one ECG signal and associated VAT may be displayed in the GUI on a beat-by-beat basis as separate cardiac cycles (e.g., one paced cardiac cycle at a time). A single cardiac cycle displayed separately may be updated on a continuous beat-by-beat basis. A pacing pulse marker may be displayed in a window of the GUI on the display unit 54, followed by the QRS waveform and associated VAT and may be updated beat-by-beat. The single-cycle beat-by-beat display may be frozen by the user to enable closer inspection. The display of a scrolling signal of multiple cardiac cycles with associated VAT and the display of a single cardiac cycle updated beat-by-beat may be switched between by the user interacting with the GUI (e.g., via a touch screen or other pointing device of the user interface 56).

[0114] In some examples, in addition to the VAT determined from the unipolar (or bipolar) left chest ECG signal, the VAT can also be determined at box 156 based on the CSP pulse delivered to the maximum peak amplitude of one or more unipolar or bipolar ECG signals (or other selected reference points of the QRS waveform after pacing). For example, the VAT can be determined based on the CSP pulse to the maximum peak amplitude of the unipolar or bipolar ECG signal, which is determined using the input signal from the right chest electrode. Two or more ECG signals can be displayed in the GUI in combination with the VAT determined from the ECG signal sensed during the CSP, and displayed for each of the multiple cardiac cycles. When the VAT is determined from multiple ECG signals, each ECG signal can be annotated with the associated VAT determined from the corresponding ECG signal.

[0115] Each of the VATs displayed at box 158 may be formatted based on the value of the corresponding VAT. For example, when the VAT is greater than or equal to a threshold value (e.g., greater than 100 milliseconds (ms) or another threshold value), the VAT may be displayed in a red font or otherwise formatted to indicate that the VAT is unlikely to be associated with capture of the conduction system. When the VAT is greater than the threshold value, a capture failure may have occurred or only the ventricular myocardium may have been captured without the conduction system being captured. When the VAT is less than the threshold value, indicating that at least a portion of the conduction system may have been captured, the VAT may be displayed in a green font or otherwise formatted to indicate possible capture of the conduction system.

[0116] At box 160, the processor 52 may compare the VAT determined for the current cardiac cycle with the VAT determined for the previous cardiac cycle. In some examples, the processor 52 may determine the VAT difference between the VATs determined according to two different cardiac cycles, which may or may not be consecutive cardiac cycles. At box 160, the processor 52 may detect a change in VAT based on the difference (or ratio or other comparative analysis) between the current or most recent VAT and the previous VAT. When the difference (or other quantitative relationship) between the two VATs is equal to or greater than a threshold difference, a change in VAT may be detected at box 160. The threshold difference may be 10ms, 20ms, 30ms, 40ms, 50ms, 60ms or any other threshold difference. The VAT difference may be determined between two consecutively determined VATs from two consecutive CSP cycles. In other examples, the VAT difference that satisfies the difference threshold may be two VATs determined within three consecutive CSP cycles, five CSP cycles, eight CSP cycles or other threshold number of CSP cycles.

[0117] In some examples, when two consecutively determined VATs meet a difference threshold, the processor 52 may detect an abrupt change in VAT, which may or may not be determined based on consecutively occurring cardiac cycles, but may be associated with two different CSP pulses delivered at different pacing sites via different pacing electrode vectors and / or with different pacing pulse outputs (different pulse amplitudes and / or pulse widths). A change in VAT from a first VAT to a second VAT may occur when a change in the delivery of a CSP pulse results in a change from non-capture of the conduction system to capture of the conduction system, or vice versa, that differs by at least the difference threshold. Thus, the processor 52 may detect a change in VAT from one paced cardiac cycle to another when the pacing site, pacing electrode vector, and / or pacing pulse output changes from one paced cardiac cycle to another.

[0118] In some examples, the VAT may be a representative VAT determined from a plurality of VATs determined during a paced cardiac cycle when a CSP pulse is delivered in the same manner (same pacing site, pacing electrode vector, and pacing pulse output). When a CSP pulse is delivered at a first pacing site using a first pacing pulse output (e.g., a first pulse amplitude and a first pulse width) and a first pacing electrode vector, the processor 52 may determine the first representative VAT as an average, median, maximum, minimum, or other representative value of a first plurality of VATs (e.g., two, three, four, six, eight, or other selected number of VATs) determined according to the paced cardiac cycle. When a CSP pulse is delivered using a second pacing pulse output and / or a second pacing electrode vector and / or a second pacing site, the second representative VAT may be determined as an average, median, maximum, minimum, or other representative VAT of a second plurality of VATs determined according to the paced cardiac cycle, wherein the second pacing pulse output, the second pacing electrode vector, and the second pacing site may each be different from the first pacing pulse output, the first pacing electrode vector, and the first pacing site, respectively. At block 160 , the processor 52 may detect a change in the VAT based on the first representative VAT and the second representative VAT satisfying a threshold difference.

[0119] It should be understood that in some cases, consecutive CSP cycles may not be consecutive cardiac cycles, as one CSP cycle may be separated from a second CSP cycle by one or more intrinsic or non-CSP cardiac cycles. For example, during a capture threshold test or an electrode placement test, when a CSP pulse is delivered at a first electrode position with a first pacing pulse output (e.g., a first pacing amplitude and pacing pulse width), VAT may be determined for one or more first CSP cardiac cycles. The first CSP cycle may be followed by one or more intrinsic cardiac cycles or non-CSP cardiac cycles. Subsequently, when a CSP pulse is delivered with a second pacing pulse output different from the first pacing pulse output (e.g., a second higher or lower pacing amplitude and / or pacing pulse width) and / or at a second electrode position different from the first electrode position, VAT may be determined by processor 52 for one or more second CSP cardiac cycles. Thus, "continuously" determined CSP cardiac cycle VAT determined based on the CSP cardiac cycle used to detect sudden changes in VAT can be separated by one or more cardiac cycles, which can be intrinsic cycles or paced cycles, where pacing is delivered at a CSP site or a non-CSP site (e.g., LV myocardium).

[0120] When the change of VAT is not detected at box 160, the processor 52 may return to box 156 to continue to determine VAT for display unit 54 to display in GUI. When the processor 52 detects the change of VAT at box 160, the processor 52 cooperates with the display unit 54 at box 162 to generate a notification or eye-catching indicator of the change in VAT in GUI. The eye-catching indicator may include any of the changes in color, size, font type, font style (e.g., bold, italic, underline, etc.), background changes, or other formatting of the displayed numerical value of VAT. The eye-catching indicator may include a text or written notification indicating that a VAT change is detected, indicating a VAT difference and / or other written notifications related to the detected VAT change and / or indicating possible changes in the capture of the conduction system. The eye-catching indicator of VAT change may additionally or alternatively include an auditory notification. The auditory notification may be an audible notification, a beep, a tone, a change in the frequency or repetition rate of a beep or tone, or other auditory signals notifying the user of the detected VAT change.

[0121] The change in VAT may be a threshold increase or decrease in VAT. A decrease in VAT that is equal to or greater than a threshold difference may indicate capture of at least a portion of the conduction system. An increase in VAT that is greater than a threshold difference may indicate a capture failure of the conduction system, which may be a complete failure of capture of the CSP pulse or only ventricular myocardium capture without capture of the conduction system. When a decrease in VAT is detected, the processor 52 may cause the display unit 54 to change the display to provide a prominent indicator of a VAT change indicating CSP capture, for example, by changing the formatting of VAT (shown as a numerical value) from red to green or another color or font or formatting change. When an increase in VAT is detected, the processor 52 may cause the display unit 54 to change the display to provide a prominent indicator of a VAT change indicating CSP capture failure (e.g., changing the display of VAT from green to red). Although a color change is one way that a VAT change may be prominently identified in the display at box 162, it should be understood that other graphics, formatting, or notification techniques may be used alone or in combination according to any of the examples listed herein, without intent to be limiting.

[0122] As long as the processor 52 continues to receive input signals, the processor 52 may continue to determine VAT and generate data for display in the GUI by the display unit 54 by returning to block 156. The user may terminate the process of the flowchart 150 at any time, for example, by disconnecting the ECG electrodes, inputting an "end" command, logging off, powering off the external device 50, etc.

[0123] Figure 8 is a conceptual diagram 200 of processing circuitry that may be included in external device 50 for obtaining differential unipolar and bipolar ECG signals, according to some examples. Figure 8The processing circuit system represented by the diagram of FIG. 5 may be implemented in hardware, firmware and / or software and may be included in an external device 50 (see Figure 1 ) in a processor 52 of the apparatus. In the example shown, the processing circuit system receives three single-ended chest electrode inputs (C1, C2, and C3) and a reference electrode input. The reference electrode may be positioned at any location on the patient's body. The C1 electrode may represent a right chest electrode, which may be placed posteriorly or anteriorly at any medial or lateral location on the sternum or to the right of the sternum. As an example, the C1 electrode may be positioned between the second intercostal space and the sixth intercostal space on the right side of the patient. The C1 electrode may be the chest electrode positioned closest to the right ventricle of the three chest electrodes to obtain an ECG signal representing right ventricular electrical activity or an ECG signal associated with right ventricular electrical activity. In some examples, the C1 electrode may be generally positioned to obtain an ECG signal representing global (right and left) ventricular activity.

[0124] The C2 electrode may represent a left chest electrode, which may be placed posteriorly or anteriorly on the sternum or at any medial or lateral position to the left of the sternum. For example, the C2 electrode may be positioned between the third intercostal space and the seventh intercostal space on the left side of the patient. The C2 electrode may be the chest electrode positioned closest to the left ventricle among the three chest electrodes to obtain an ECG signal representing the electrical activity of the left ventricle or an ECG signal associated with the electrical activity of the left ventricle. In other examples, the C2 electrode may be generally positioned to obtain an ECG signal representing the global electrical activity of the ventricle.

[0125] The C3 electrode represents the third chest electrode, which can be placed anywhere, for example, above the abdomen or last rib and below the neck or below the sternum, posteriorly or anteriorly, medially or laterally. In one example, the C3 electrode is positioned on the left chest at approximately the level of the first to fourth intercostal spaces, but other locations may be used. The three chest electrodes may be positioned in a triangular configuration that is approximately centered on the heart or ventricle.

[0126] Any combination of single-ended input signals may be used to determine a common mode signal, which may represent a center terminal signal for calculating a differential unipolar signal for at least one of the chest electrodes C1, C2, and / or C3. In one example, the four input signals from the C1, C2, C3, and reference electrodes are summed, as indicated by the summing circuit system 202, for determining a common mode (CM) signal. In an example, the summing circuit system 202 sums the C1, C2, C3, and reference input signals and performs a divide-by operation (e.g., a divide-by-two operation) to output a common mode (CM) signal 204.

[0127] The differential unipolar C1 signal 210 may be determined as the difference between the C1 input signal and the CM signal 204. The differential unipolar C2 signal 208 may be determined as the difference between the C2 input signal and the CM signal 204. The differential unipolar C3 signal 206 may be determined as the difference between the C3 input signal and the CM signal 204.

[0128] The first differential bipolar signal 216 may be determined as the difference between the unipolar C1 signal 210 and the unipolar C3 signal 206. The second differential bipolar signal 214 may be determined as the difference between the unipolar C1 signal 210 and the unipolar C2 signal 208. The third differential bipolar signal 212 may be determined as the difference between the unipolar C2 signal 208 and the unipolar C3 signal 206. Thus, in some examples, the three chest electrodes and the reference electrode provide input signals to the processing circuit system of the external device 50, from which the processing circuit system may obtain up to three unipolar ECG signals (206, 208, and 210) and three bipolar ECG signals (212, 214, and 216). In other examples, at least one unipolar ECG signal (e.g., unipolar C2 signal 208) may be determined based on the left chest electrode C2 input signal for determining VAT. In some examples, additional unipolar ECG signals, such as the unipolar C1 signal 210, may be determined using the right chest electrode C1 input signal.

[0129] Although through Figure 8 The processing circuitry represented in is capable of obtaining up to three unipolar ECG signals and optionally up to three bipolar ECG signals, but it will be appreciated that a greater number of ECG signals can be obtained when additional chest electrodes are placed on the patient. However, a minimum number of electrodes may be used to simplify and shorten the setup process required for the processor 52 to obtain ECG signals from which CSP-related data may be determined for presentation to the user in the GUI.

[0130] Fig. 9 3 is a conceptual diagram of a GUI 300 that may be displayed on the display unit 54 of the external device 50 according to one example. The GUI 300 includes a display of three ECG signals 302, 304, and 306, an atrial (A) EGM signal 308, and a ventricular (V) EGM signal 310. The processor 52 may use the above combination Figure 8 The three ECG signals 302, 304 and 306 are obtained by using the described techniques. Fig. 9 In the example of FIG. 5 , the processor 52 obtains at least three unipolar ECG signals from input signals received from a reference electrode and three chest electrodes, which may be as shown in FIG. Figure 1 ECG 1 302 may represent a 302-degree angle obtained using the right chest electrode C1. Figure 8The unipolar C1 ECG signal 210 shown in FIG. 2 , for example, is a differential unipolar signal determined as the difference between the common mode (or center terminal) signal and the input signal from the C1 electrode.

[0131] ECG 2 304 may represent a pulse obtained using left chest electrode C2. Figure 8 , for example, a differential unipolar signal determined as the difference between the common mode (or center terminal) signal and the input signal from the C2 electrode. ECG 3 306 may represent a unipolar C3 ECG signal 206 associated with a third chest electrode C3, for example, a differential unipolar signal determined as the difference between the common mode (or center terminal signal) and the input signal from the C3 electrode. In other examples, as Fig. 9 In addition to or in place of the unipolar ECG signal shown in Figure 8 Any of the bipolar ECG signals described above may be obtained and displayed by processor 52. In addition, it should be understood that although Fig. 9 In the example of FIG. 3 , three ECG signals are displayed, but in other examples, zero, one, two, or more than three ECG signals may be displayed in GUI 300 .

[0132] In some examples, processor 52 obtains information associated with the left chest electrode (e.g., Figure 1 In some examples, processor 52 obtains at least ECG 2 304 associated with the right chest electrode (e.g., C2 electrode 42 shown in FIG. 4 ) for determining VAT. Figure 1 300 and at least one of the ECG 1 302 and / or the ECG 2 304 associated with the left chest electrode and at least one of the ECG 1 302 and / or the ECG 2 304 is displayed in the GUI 300. The ECG 1 302 associated with the right chest electrode may be displayed to provide a user with a visual representation of the electrical activity of the right ventricle. The QRS waveform of the ECG 1302 may present the appearance of RBB block. In some patients, there may be a pathological RBB block condition, which may be observed in the ECG 1 302. In other cases, when the CSP captures the LBB earlier than the depolarization of the RBB, there may be a pacing-induced RBB block condition, which may be observed in the ECG 1 302 displayed in the GUI 300.

[0133] The ECG 2 304 associated with the left chest electrode may be displayed to provide a user with a visual representation of the electrical activity of the left ventricle. When the CSP captures at least a portion of the conduction system, the induced depolarization and subsequent LV myocardial depolarization via the LBB may result in a relatively short VAT, which is measured as the time interval from the delivered CSP pulse to the maximum (positive or negative) amplitude of the ECG 2 304. Therefore, the processor 52 may obtain the ECG 2 304 associated with the left chest electrode, determine the VAT for each of a plurality of paced cardiac cycles, and display the VAT 312. In other examples, different reference points of the QRS waveform of the ECG signal may be used to determine the VAT instead of the maximum amplitude (which may be the absolute maximum amplitude). For example, the processor 52 may identify the maximum positive slope, the maximum negative slope, the amplitude threshold crossing (earliest or latest, positive or negative), the return to the baseline at the end of the QRS waveform, or other reference QRS waveform points. The processor 52 and the display unit 54 may be configured to cooperatively generate a display of the VAT determined for each of the plurality of pacing pulses. The ECG 1 302 and / or the ECG 2 304 may be displayed with the determined VAT. For example, a plurality of paced cardiac cycles of the ECG 1 302 and / or the ECG 2 304 may be displayed, wherein each paced cardiac cycle is annotated with the VAT 312 determined according to the paced cardiac cycle.

[0134] Atrial EGM signal 308 and ventricular EGM signal 310 may optionally be displayed as being aligned in time with one or more ECG signals 302, 304, and 306. Each of atrial EGM signal 308 and ventricular EGM signal 310 may be transmitted by IMD 14 to external device 50, received by external device telemetry unit 58, and passed to display unit 54 for display in GUI 300.

[0135] The GUI 300 may include pacing markers 316 and 318 that indicate the timing of delivered atrial pacing pulses and ventricular pacing pulses, respectively, relative to the ECG signal and / or ECG signal displayed in the GUI 300. In some examples, the ventricular pacing marker 318 may be shown to be aligned in time with each of a plurality of paced cardiac cycles of ECG 1 302 and / or ECG 2 304 and / or an associated VAT determined for each of these paced cardiac cycles. It should be understood that the ventricular pacing marker 318 may represent the timing of a CSP pulse delivered via the conduction system to pace the ventricles. However, in some cases, the ventricular pacing marker 318 may indicate the timing of a CSP pulse for a paced cardiac cycle that does not capture the conduction system. Thus, each ventricular pacing marker 318 may mark the timing of a CSP pulse that captures at least a portion of the conduction system, captures only the ventricular muscle without capturing the conduction system, or fails to capture (capture failure).

[0136] For example, the ventricular pacing marker 318 may mark the timing of a CSP pulse that is delivered at a poor location for capturing the conduction system and / or delivered at a pacing pulse energy that is less than a conduction system capture threshold. By displaying a VAT formatted according to the value of a VAT and / or a relative difference from another VAT in the GUI 300, as further described below, a user may easily identify and distinguish between paced cardiac cycles associated with conduction system capture and paced cardiac cycles associated with failure to capture the conduction system. In this manner, the electrophysiology equipment, user expertise, time burden borne by the user in reviewing and analyzing ECG signals, and the possibility of user error in selecting a CSP electrode implantation site, a CSP electrode vector, and a pacing pulse output for capturing the conduction system may be minimized.

[0137] In the example of the GUI 300, a plurality of paced cardiac cycles of at least one ECG signal are annotated with corresponding VAT 312. The processor 52 may be configured to compare the determined VAT to a threshold. The threshold may be defined based on an expected maximum VAT when a CSP pulse captures at least a portion of the conduction system. A VAT greater than the threshold may indicate a CSP capture failure, even though ventricular myocardial capture without CSP capture may still be occurring. When the VAT is greater than the threshold, the display unit 54 may display the VAT according to a first format. When the VAT is less than the threshold, the display unit 54 may display the VAT according to a second format different from the first format. As an example, the first format and the second format may include different font types, different font colors and / or background colors, different font sizes, different font styles (e.g., bold, underlined, italic, etc.), or any combination thereof.

[0138] In some examples, the processor 52 may be configured to detect when a difference (or ratio) between a first VAT determined for a first pacing pulse and a second VAT determined for a second pacing pulse satisfies a threshold difference. The display unit 54 may be configured to coordinate with the processor 52, in response to the processor detecting the threshold difference between the first VAT and the second VAT, adjust the display of the determined VAT by displaying the first VAT of the determined VAT according to a first format and displaying the second VAT of the determined VAT according to a second format different from the first format. The display unit 54, in coordination with the processor 52, may be configured to display the VAT determined for a plurality of paced cardiac cycles, determine when the threshold difference between the two VATs is met, and display a prominent indicator in response to determining that the threshold difference is met. The display unit 54 may generate the display of the prominent indicator that the threshold difference is met by generating a visual notification, generating an auditory notification, adjusting or changing the format of the displayed ventricular activation times to be different from the previously displayed ventricular activation times, and / or adjusting or changing the background of the displayed ventricular activation times. The display unit 54 may be configured to display the activation times determined for a plurality of cardiac cycles and / or the activation time differences determined for a plurality of cardiac cycles in a GUI (either individually one cardiac cycle at a time or simultaneously).

[0139] like Fig. 9 As shown, the difference between the last VAT 314 and the first three VATs is greater than 20ms. As an example, such a change in the VAT that meets the threshold difference can be detected by the processor 52, so that the formatting of the VAT 314 is adjusted by the display unit 54 to a larger and / or bold font and / or can be displayed with a different font color and / or a different background. For example, as an example, a VAT 312 greater than a threshold of 90ms can be displayed in a red font, while a last VAT 314 less than the threshold and / or less than the threshold difference of the previous VAT can be displayed in a green font, bold and / or enlarged font.

[0140] In some examples, an audible or text alert may be generated by the display unit 54 to notify the user of the change in VAT. Fig. 9 300, but it should be understood that the VAT may decrease or increase and may change back and forth between relatively longer values ​​and relatively shorter values ​​during CSP capture threshold testing and / or positioning of pacing electrodes and / or testing of different pacing electrode vectors. Therefore, the display unit 54 may adjust the display of the VAT shown in the GUI 300 multiple times based on comparison with the threshold and / or based on comparison of the VAT difference with the threshold difference to provide a prominent indicator of the threshold change in the VAT.

[0141] In some examples, the display unit 54 is further configured to display the ECG signal (in the illustrated example, ECG 2 304) used to determine the VAT and a visual marker of at least one of the identified reference points of the ECG signal used to determine the VAT, along with the determined VAT 312 and 314. In the illustrated example, the time interval from the delivered CSP pulse indicated by the ventricular pacing marker 318 to the maximum peak amplitude (which is the negative polarity peak in the ECG 2 304) is determined as the VAT 312. The display unit 54 may display one or more markers 315 that may be used by the processor 52 to determine the identified reference point of the VAT. In the illustrated example, each paced cardiac cycle of the ECG 2 304 is annotated with the VAT 312 or 314 determined for the corresponding paced cardiac cycle, and the visual marker 315 is displayed (in the illustrated example). Fig. 9 314) to mark each maximum peak of the pacing-induced QRS waveform used in determining VAT 312 and 314. In other examples, the visual markers may include a horizontal line or arrow extending from the ventricular pacing marker 318 to the time of a reference point and / or a symbol (e.g., a circle, triangle, square, or other symbol) marking a reference point used to determine VAT relative to an immediately preceding CSP pulse.

[0142] GUI 300 may include various icons, menus, windows, patient information, IMD information, etc. Fig. 9 These icons, menus, windows, patient information, IMD information, etc., as generally shown in 320 of FIG. 1 , enable a user to identify a patient, the type of IMD implanted in the patient, a programmed pacing mode, atrial lower rate, ventricular lower rate, AV delay (AVD), or other device-related or patient-related information. The various icons and menus may enable a user to transition between GUI screens or windows, change the speed of a scrolling ECG signal display, zoom in or out, freeze the display, store a screenshot of the display, print a screen, or perform other operations.

[0143] Fig.10 4 is a conceptual diagram of two different screenshots 400 and 450 that may be displayed at different times in a GUI by the display unit 54 in coordination with the processor 52 according to another example. In this example, the processor 52 and the display unit 54 are configured to obtain at least one ECG signal and display each of a plurality of paced cardiac cycles one at a time. Individual paced cardiac cycles may be displayed in the GUI, for example, as depicted by an image of the screenshot 400 corresponding to one paced cardiac cycle and then an image of the screenshot 450 corresponding to the next paced cardiac cycle. Each individual cardiac cycle displayed one at a time in the GUI may be annotated with a VAT determined for that paced cardiac cycle.

[0144] As shown in the screenshot 400, the display unit 54 may display a single paced cardiac cycle of ECG 1 402 and / or ECG 2 404. ECG 1 402 may correspond to a unipolar C1 ECG signal sensed using the right chest electrodes as described above. ECG 2 404 may correspond to a unipolar C2 ECG signal sensed using the left chest electrodes as described above. In other examples, in addition to or instead of the unipolar ECG signals 402 and 404, a combination of the ECG signals 402 and 404 may be displayed. Figure 8 The described technique derives one or more bipolar ECG signals from a unipolar ECG signal obtained by processor 52. A single paced cardiac cycle of at least one ECG signal obtained by processor 52 may be displayed along with pacing markers 416 and 418 indicating the timing of delivered atrial pacing pulses and ventricular pacing pulses, respectively, where ventricular pacing marker 418 may represent a CSP pulse that may or may not capture the conduction system.

[0145] The VAT 412 determined for the paced cardiac cycle shown in the screenshot 400 is displayed according to a first formatting scheme based on the value of the VAT 412 and / or the relative difference between the VAT 412 and another VAT determined for a different paced cardiac cycle. For example, because the VAT 412 is greater than the threshold VAT, the display unit 54 may display the VAT 412 in a red font in the example. The font may be non-bold, relatively small in size, or otherwise prominently displayed to indicate that conduction system capture is not possible. As an example, the threshold VAT may be 80ms, 85ms, 90ms, 95ms, or 100ms, but is not intended to be limiting. The formatting of the VAT 412 indicates to the user that the value (102ms in this illustrative example) indicates that the conduction system is not captured (or failed to capture). The formatting of the separate VAT 412 may indicate to the user that at least one of a higher pacing pulse output, a different CSP electrode position, and / or a different CSP electrode vector needs to be adjusted to achieve capture of the conduction system. In other examples, text and / or an audible notification may indicate that conduction system capture did not occur. Other device-related information (e.g., atrial lower rate, ventricular lower rate, pacing mode, AV delay, remaining IMD battery life, etc.), patient-related data, and / or various icons, menus, or other user interface features may be displayed in the GUI represented by screenshot 400.

[0146] Screen shot 450 shows a display of a paced cardiac cycle different from the paced cardiac cycle displayed in screen shot 400, ECG 1 452 (corresponding to the same ECG signal as ECG 1 402, but a different paced cardiac cycle) and ECG 2 454 (corresponding to the same ECG signal as ECG 2 404, but a different paced cardiac cycle). In this case, ventricular pacing marker 458 (delivered with an AV delay from atrial pacing marker 456) represents a CSP pulse that captures at least a portion of the conduction system. The displayed VAT 464 may be formatted according to a second formatting scheme to indicate that VAT 464 represents capture of at least a portion of the conduction system. VAT 464 may be displayed in a different color font (e.g., green font), a different font style (e.g., bold font), and / or a larger font size than the display of VAT 412 to provide the user with an adjustment or altered format of the displayed VAT as a prominent indicator that the CSP pulse represented by ventricular pacing marker 458 may have captured at least a portion of the conduction system. In response to processor 52 determining that VAT 464 is less than a threshold VAT indicating conduction system capture and / or that the difference between VAT 412 and VAT 412 is greater than a threshold difference, VAT 464 may be formatted differently than the formatting of VAT 464. As described above in conjunction with Fig. 9 Generally described, visual markers 415 and 465 may be displayed in the GUI to indicate to the user the fiducial points of the QRS waveform in the ECG signal 404 or 454 that are identified by the processor 52 and used to calculate VAT 412 and 464 relative to corresponding ventricular pacing markers 418 and 458, respectively.

[0147] Fig.11 500 is a flow chart of a method for displaying CSP-related data in a GUI by a medical device according to another example. At block 502, according to any of the examples described herein, the processor 52 receives input signals from a plurality of chest electrodes (e.g., at least one right chest electrode and at least one left chest electrode and a reference electrode). Generally, as is typically done during a cardiac electrophysiology study, less than ten input signals are received as needed to display a 12-lead ECG. As in the case of a combination of Figure 8 As described, the input signal may be composed of four single-ended input signals received by the processor 52 from three chest electrodes and one reference electrode, so that at box 504, the processor 52 can obtain up to three unipolar ECG signals and / or up to three bipolar ECG signals by determining a common mode (or center terminal) signal from the input signal and using the common mode (or center terminal) signal to derive at least one differential unipolar ECG signal and, in at least some examples, one or more differential bipolar ECG signals.

[0148] At block 506, the processor 52 determines VAT from a first ECG signal of the plurality of ECG signals obtained by the processor 52. The ECG signal used at block 506 for determining VAT may be a unipolar C2 ECG signal determined as being received from a left chest electrode (e.g., Figure 1 The processor 52 may be a processor that determines the VAT of at least one paced cardiac cycle. In general, the processor 52 determines the VAT of each paced cardiac cycle of two or more paced cardiac cycles.

[0149] For example, during a CSP capture threshold test, two or more paced cardiac cycles where VAT is determined by processor 52 may include different pacing pulse energies for the delivered pacing pulses. For example, during an implantation procedure, when a CSP lead 18 (e.g., Figure 1 ) or a pacemaker 114 (e.g., Figure 4 and Figure 5 When a pacing electrode (shown in ) is advanced to the implantation site to deliver CSP, two or more paced cardiac cycles may include different pacing electrode sites. Two or more paced cardiac cycles may include different CSP electrode vectors, such as unipolar pacing electrode vectors, bipolar pacing electrode vectors, and / or bipolar pacing electrode vectors with reversed cathode polarity and anode polarity. Different CSP electrode vectors may be tested during an implantation procedure, CSP capture threshold testing, or other patient follow-up procedures. Therefore, in some cases, two or more paced cardiac cycles may each be paced according to different CSP control parameters to enable a user to identify CSP control parameters and / or CSP electrode vectors and / or CSP electrode sites that successfully achieve CSP capture and improved ventricular electrical synchrony.

[0150] At block 508, processor 52 may determine one or more additional metrics for confirming CSP capture and / or the location of the CSP electrode. Figure 1 The ECG signal used to determine the metric at block 508 may be a unipolar C1 ECG signal determined as the difference between the input signal from the C1 electrode and the center terminal signal, or a bipolar ECG signal determined using a unipolar C1 ECG signal and another unipolar ECG signal, such as a combination of Figure 8Generally described. One metric that can be determined at box 508 is QRS width. QRS width can be determined as the time interval from the delivered CSP pulse to the reference point of the QRS waveform. The reference point can be close to the end time of the QRS waveform. In examples of reference points that can be identified by processor 52 and used to determine QRS width, there is an amplitude threshold crossing, a maximum negative slope, a dV / dt (or slope) threshold crossing, or the earliest baseline point of the ECG signal after the maximum peak of the QRS waveform (indicating a return to baseline).

[0151] An additional or alternative metric that may be determined by the processor 52 using the second ECG signal may be the QRS area of ​​the second ECG signal following the delivered CSP pulse. A metric that may be determined by the processor 52 using the second ECG signal may be a second excitation time, which is determined as the time interval from the CSP pulse to the maximum peak amplitude (or another reference point) of the QRS waveform of the second ECG signal. An additional or alternative metric that may be determined by the processor 52 using the second ECG signal may be the peak time interval between the peak amplitude of the first ECG signal used to determine VAT and the peak amplitude of the second ECG signal following the delivered CSP pulse.

[0152] Other metrics determined at block 508 may include a QRS morphology change metric. The QRS morphology change metric may be determined based on an ECG signal obtained by the processor 52 using the right chest electrode, such as the unipolar C1 ECG signal described above or a bipolar ECG signal obtained using the unipolar C1 ECG signal. The QRS morphology change metric of the ECG signal obtained using the right chest electrode may indicate when RBB block occurs during LBB pacing and when the RBB block morphology caused by LBB pacing is corrected. The QRS morphology change metric may be a ratio, difference, or other quantitative relationship or relative comparison between the absolute values ​​of the peak amplitudes of the QRS waveform. For example, the QRS morphology metric may be a comparison of the R wave peak amplitude to the Q wave peak amplitude (absolute value). When a QR morphology is identified based on the R wave peak (e.g., the second peak of the QRS waveform) being greater than the Q wave peak (e.g., the first peak of the QRS waveform), the processor 52 may detect a non-RBB block morphology. When the second peak of the QRS waveform is less than the first peak (which may be associated with a Qr or QS morphology), the RBB block morphology may be detected by the processor 52.

[0153] In other examples, the QRS morphology metric may be determined by the processor 52 as a morphology match score or waveform correlation metric determined between the QRS waveform and a previous QRS waveform or a previously established QRS waveform template, e.g., associated with a non-RBB block morphology. For example, the QRS morphology metric may be determined using a Haar transform or other wavelet transform. After adjusting the CSP pulse output and / or CSP electrode position, the QRS morphology metric may be determined on a beat-by-beat basis or from every nth paced cardiac cycle.

[0154] When the process of flowchart 500 is performed during an implantation procedure for locating electrodes of a CSP (e.g., in the region of an LBB), processor 52 may determine additional metrics by detecting LBB potential signals and / or injury currents at block 508. Processor 52 may analyze EGM signals received via leads 18 or transmitted from IMD 14 to detect LBB potential signals for use in confirming that the CSP electrodes (e.g., Figure 1 The LBB potential signal is a signal spike that appears in the EGM signal, which is immediately before the QRS signal accompanied by ventricular myocardial depolarization. The LBB potential signal represents the potential that is conducted along the LBB and causes ventricular myocardial depolarization.

[0155] In other examples, the injury current signal may be detected by the processor 52 based on analysis of the EGM received by the processor 52 during the intrinsic ventricular rhythm and sensed using, for example, a CSP electrode positioned in the region of the LBB. The increased amplitude of the EGM signal immediately following the LBB potential signal is evidence of the injury current. Thus, the increased amplitude following the LBB potential signal indicates that the CSP is located in the left portion of the ventricular septum, resulting in localized injury near the LBB.

[0156] The processor 52 may detect an injury current by determining and storing a baseline amplitude of the EGM signal (which may be an average baseline), detecting an LBB potential signal and determining a maximum amplitude within an injury current detection window after the LBB potential signal. As an example, the injury current detection window may extend up to 10 ms, up to 20 ms, or up to 25 ms after the LBB potential signal. The processor 52 may determine a difference between a baseline amplitude of the EGM signal (e.g., before the LBB potential signal) and an amplitude during the injury current detection window. When this amplitude difference between the EGM signal amplitude just before the LBB potential signal and just after the LBB potential signal is greater than a threshold amplitude difference or percentage change (e.g., at least a 0.1 millivolt to 1 millivolt difference), an injury current indicative of an LBB region orientation of the CSP electrode may be detected by the processor 52.

[0157] At block 510, the display unit 54 may display in a GUI the determined VAT, the difference between consecutively determined VATs, and / or one or more of the metrics determined at block 508 and / or changes in one or more of the metrics determined at block 508. An example of a GUI that may include a display of metrics determined from a second ECG signal is shown in FIG. Fig.12 and Fig.13 512 and described below. As generally described above, the display unit 54 may display a striking indicator in response to determining that the threshold difference between the VATs is met at box 512. The display unit 54 may adjust the display of the VAT at box 514 in response to the processor 52 detecting a change in the determined VAT that satisfies the threshold difference (or is less than the threshold) at box 512. The display of the VAT can be adjusted by changing the formatting of the displayed VAT, adding flashing text or icons, and / or adding visual and / or auditory notifications of the detected VAT changes. As further described below, in some examples, the processor 52 may be configured to detect a change in a metric determined using a second ECG signal or EGM signal at box 512, and in response to detecting the change, for example, by adjusting the display of the metric by changing the formatting of the displayed metric and / or adding visual or auditory notifications of the change of the metric at box 514 to display a striking indicator. Any of the example metrics described herein may be displayed in conjunction with at least one ECG signal, VAT (and / or determined VAT difference), CSP pulse markers, and optionally at least one EGM signal.

[0158] Fig.12 is a diagram of a GUI 550 that may be cooperatively generated by the processor 52 and the display unit 54 to be displayed on the display unit 54 according to another example. Fig.12 The same reference numerals shown in Fig. 9 Like numbered elements as shown in and described above. Fig.12In the example of , the display unit 54 may be configured to display one or more metrics determined using a second ECG signal obtained by the processor 52. At least one ECG signal may be annotated with a VAT 312, as generally described above. A QRS width 322 determined by the processor 52 for at least one paced cardiac cycle based on ECG 1 (or another, not displayed, ECG signal obtained by the processor 52) may be displayed. Additionally or alternatively, a peak-to-peak time interval 324 determined by the processor 52 using ECG 1 and ECG 2 (or another, not displayed, ECG signal obtained by the processor 52) may be displayed for at least one paced cardiac cycle. In the example shown, each cardiac cycle following a ventricular pacing marker 318 representing a delivered CSP pulse may be annotated with metrics determined based on a second ECG signal (different from the ECG signal used to determine the VAT) and the determined VAT and / or metrics determined based on the ventricular EGM signal 310 (e.g., LBB potential signal detection and / or injury current detection).

[0159] Additionally or alternatively, the processor 52 can be configured to measure impedance (Z) 326 using a CSP electrode (e.g., using the pacing electrode 32 of the CSP lead 18 or the housing-based electrode 102 of the leadless pacemaker 114). The impedance 326 measured using the pacing electrode for delivering CSP is also referred to herein as "CSP impedance". The CSP impedance 326 can be displayed in the GUI 550 on a beat-by-beat basis. In some cases, during an implantation procedure, the impedance 326 can be measured by the processor 52 as the pacing electrode 32 at the tip of the CSP lead 18 is advanced toward the CSP site. Low impedance can indicate that the pacing electrode 32 at the tip of the CSP lead 18 is in a blood pool and may need to be further advanced into the tissue or may need to be retracted after over-advancement (e.g., through the ventricular septum). Therefore, the impedance measured by the processor 52 during the delivery of an impedance measurement drive signal (e.g., which may be generated by the pulse generator 60) can be displayed in the GUI 550 for one or more paced cardiac cycles.

[0160] When displaying information such as QRS width 322, QRS area ( Fig.12 Not shown), QRS morphology measurement ( Fig.12When the displayed metric does not indicate conduction system capture or does not indicate improvement in ventricular electrical synchrony (e.g., LBB capture but with pacing-induced RBB block as indicated by a QRS width or peak-to-peak interval greater than a threshold), the metric may be formatted according to a first formatting scheme. When the displayed metric indicates conduction system capture with improved ventricular electrical synchrony, the metric may be formatted according to a second formatting scheme that is different from the first formatting scheme. For example, when the peak-to-peak interval or QRS width changes from greater than a threshold to less than a threshold and / or indicates a threshold change relative to a previous peak-to-peak interval or QRS width, respectively, the formatting of the peak-to-peak interval and / or QRS width may change in font, font color, font style, font size, background color, flashing text, or any combination thereof. It should be understood that in addition to or instead of displaying the beat-to-beat value of a given metric, a beat-to-beat difference, percentage change, or other relative change measure for a given metric may be displayed in the GUI.

[0161] When the impedance is below a threshold impedance indicating that the pacing electrode 32 (or pacemaker electrode 102) is located in the blood pool, the impedance 326 may be displayed according to one formatting scheme. When the impedance is above the threshold impedance, the impedance 326 may be displayed according to a second formatting scheme different from the first formatting scheme.

[0162] Although QRS width and peak time interval are shown in GUI 550 as illustrative examples of additional metrics that may be determined and displayed in conjunction with VAT data and at least one ECG signal, it should be understood that any of the example metrics described herein may be displayed alone or in any combination in any of the example GUIs shown and described herein in conjunction with at least one ECG signal and VAT (and / or VAT difference). VAT and / or VAT difference may be determined based on an ECG signal obtained by processor 52 that is a different ECG signal than the displayed ECG signal. Among the other metrics (or differences or changes thereto) that may be displayed are VAT determined based on one or more additional ECG signals, as described above in conjunction with Fig.11 The QRS morphology metric, the indicator of LBB potential signal detection and / or the indicator of injury current detection.

[0163] Fig.13 is a conceptual diagram of two different screenshots 600 and 650 that may be displayed at different times in a GUI by the display unit 54 in coordination with the processor 52 according to another example. Fig.13 The same numbered elements in the Fig.10600 and 650. In this example, the processor 52 and the display unit 54 are configured to determine and display a metric determined using the second ECG signal in addition to the VAT that annotates each individual cardiac cycle displayed one at a time in the GUI. In the example shown, QRS width 602 and QRS width 652 are shown for each of the two different cardiac cycles displayed in the respective screenshots 600 and 650.

[0164] When the QRS width 652 changes from greater than a threshold width to less than a threshold width and / or when the difference between the two QRS widths 602 and 652 is greater than a threshold difference, the display of the QRS width 602 may be adjusted or changed from the display of the QRS width 652. Different formatting may be applied to the QRS width 652 to provide a user with a striking indicator of improved ventricular synchrony compared to the formatting applied to the QRS width 602. In some cases, when the LBB is captured by the CSP pulse, the VAT 464 may be shortened, but the QRS width determined from the ECG signal obtained using the right chest electrode (corresponding to right ventricular excitation) may remain relatively long or even increase due to pacing-induced RBB block. The timing of the CSP pulse may be adjusted, for example, by adjusting the AV delay to shorten the QRS width. Therefore, the change in the formatting applied to the displayed VAT 464 may or may not occur on the same cardiac cycle compared to the formatting applied to the QRS width 652 (or another determined metric). The CSP control parameters can be adjusted by the user (or automatically via programmed commands sent from the external device 50 to the IMD 14 or pacemaker 114) until both the QRS width (or another metric) and VAT are displayed according to a formatting scheme (e.g., green font, bold, and / or enlarged font size as examples) that indicates that CSP capture has improved ventricular electrical synchrony compared to a formatting scheme that indicates a failure of capture of the conduction system and / or a lack of improvement in ventricular electrical synchrony.

[0165] The measured impedances 604 and 654 may optionally be shown in the GUI represented by the screenshots 600 and 650. The measured impedance may indicate to the user when the CSP electrode is located within the cardiac tissue or in the blood pool. For example, in both screenshots 600 and 650, the impedance is relatively high (e.g., greater than 100 ohms or greater than 200 ohms), indicating that the CSP electrode is located in the cardiac tissue rather than in the blood pool of the cardiac chamber. Therefore, the impedances 604 and 654 may be displayed according to a formatting scheme indicating that the impedance is acceptable and the CSP electrode is located within the cardiac tissue. For example, both the impedances 605 and 654 may be shown in green, bold font, or according to another formatting scheme indicating that the impedance is at an acceptable value. When the impedance is low, such as less than a threshold impedance corresponding to the CSP electrode being in the blood pool of the cardiac chamber, the impedance may be displayed according to a different formatting scheme (e.g., red font) to indicate that the impedance is unacceptable because the CSP electrode may be located in the blood pool. For example, the impedance displayed in red font indicates to the user that the position of the pacing electrode needs to be adjusted.

[0166] In various examples, two or more parameters (e.g., VAT, QRS width, QRS area, peak-to-peak time interval, QRS morphology metrics, LBB potential signal detection, lesion current detection, and / or CSP impedance) can be displayed for each cardiac cycle of multiple paced cardiac cycles, either individually one at a time or in groups of cardiac cycles (e.g., displayed in a scrolling manner). The display of cardiac cycles of one or more ECG signals annotated with VAT and optionally one or more metrics determined using a second ECG signal, a ventricular EGM signal, and / or CSP impedance can be displayed in a manner such as Fig.10 and Fig.13 The single cycle shown in the figure is similar to that shown in Fig. 9 and Fig.12 toggles back and forth between the scrolling or still multi-cycle display shown in .

[0167] When two or more parameters are determined and displayed by the processor 52 based on the ECG signals obtained by the processor 52 (the two or more parameters may be displayed together with at least one of the obtained ECG signals), the formatting of the two or more parameters may be adjusted from one cardiac cycle to the next cardiac cycle based on each individual value of the corresponding parameter. Among the two or more parameters, there may be VAT, QRS width, QRS area, peak-to-peak time interval, QRS morphology matching score or other QRS morphology metrics, LBB potential signal detection (or not displayed), injury current detection (or not displayed), and / or CSP impedance. Since the displayed parameters may not change relative to the threshold and / or relative to the previous value of the given parameter on the same cardiac cycle, the formatting of one parameter may be maintained according to the first formatting scheme, while the formatting of the second parameter may be adjusted to the second formatting scheme based on the respective values ​​of the corresponding parameters. The processor 52 and the display unit 54 may cooperatively adjust the format of each of the two or more parameters as each corresponding parameter is determined to change the threshold difference and / or meet the threshold.

[0168] refer to Fig.13 As an illustrative example, a first format of displayed parameter values ​​may include red font, and a second format of displayed values ​​may include green font. CSP impedances 604 and 654 may be displayed in green font to indicate that the impedance values ​​may correspond to the tissue site of the CSP electrode, rather than to a site within a blood pool of a vein or heart chamber. When the impedance is less than a threshold value (e.g., less than 100 ohms), the CSP impedance may be displayed in red, indicating that the CSP electrode should be further advanced, retracted, or otherwise adjusted. Fig.13 6, CSP impedance 605 may be displayed in green font in the image represented by screenshot 600. However, both QRS width 602 and VAT 412 may be displayed in red font in screenshot 600 because both are greater than respective thresholds associated with CSP capture and improved ventricular electrical synchrony.

[0169] Referring to the screenshot 650, when the VAT 464 drops below the threshold and / or decreases the threshold difference (or threshold percentage) from the VAT 464 shown in red font, the display unit 54 may display the VAT 412 in green font. When the QRS width 652 drops below the threshold and / or decreases the threshold difference (or threshold percentage) from the QRS width 652 shown in red font, the display unit 54 may display the QRS width 602 in green font. For each cardiac cycle shown in the screenshot 650, the adjusted format is applied to both the VAT 464 and the QRS width 652. However, it should be understood that in some cases, in a given cardiac cycle, the QRS width 652 may still be greater than the threshold and still be displayed in the first format (e.g., red font), while the VAT may have decreased to a value that results in the adjusted format (e.g., a change from red font to green font) to provide a striking indicator that CSP capture has occurred. The QRS width or other QRS morphology metric determined using the ECG signal obtained from the right chest electrode signal may remain displayed in a first format (e.g., red font) until further adjustments are made to the CSP pulse output, CSP electrode vector, CSP electrode position, and / or CSP pulse timing (e.g., AV delay) and a threshold change in the QRS width (or other metric) is detected that indicates that CSP capture with improved ventricular electrical synchrony has been achieved.

[0170] Thus, depending on the value of each individual parameter, the combination of metrics or parameter values ​​determined by processor 52 may be displayed in a combination of formats. A user interacting with the GUI may adjust one or more of the CSP electrode site, CSP electrode vector, CSP pulse output (e.g., pacing pulse amplitude and / or pulse width), CSP time interval (e.g., AV delay), or other CSP control parameters until all displayed parameter values ​​or metrics are presented according to a format (e.g., green font) that prominently indicates proper CSP electrode placement, CSP capture, and improved ventricular electrical synchrony. In this manner, the display of CSP-related data and signals according to the techniques disclosed herein may simplify and expedite the process of assessing CSP, selecting CSP control parameters, adjusting CSP electrode sites, selecting CSP electrode vectors, and verifying improved ventricular electrical synchrony during CSP.

[0171] In some examples, VAT (and / or a difference in VAT relative to a previous cardiac cycle) may be displayed in the GUI 600 without additional metrics (such as QRS width 602) until a threshold difference in VAT is detected. When VAT is determined to be a reduced threshold difference and / or less than a threshold VAT, a prominent indicator of the detected VAT change may be displayed in the second screenshot 650 in combination with one or more additional metrics determined using another ECG signal and / or an EGM signal. In this way, once CSP capture can be verified based on a reduction in VAT determined in this example from the ECG 2404 / 454, the processor 52 and the display unit 54 may be configured to collaboratively determine and display one or more additional metrics for verifying CSP capture in the absence of RBB block and / or proper CSP electrode placement. For example, once a VAT change is detected, a display of QRS width 652, impedance 654, QRS area, peak time interval, QRS morphology metrics, LBB potential signal detection, and / or injury current detection can be added (alone or in any combination) to the display of VAT and / or VAT difference. Although not required in all examples, at least one ECG signal can be displayed with the determined metrics and optionally at least one EGM signal.

[0172] Thus, the first screen of the GUI displayed by the display unit 54 (e.g., screenshot 600) may include a display of one or more VATs that are greater than a threshold, do not meet a threshold difference, and do not indicate CSP capture. The second screen of the GUI (e.g., screenshot 650) may include a striking indicator of a change in the detected VAT that meets the threshold difference and indicates CSP capture. The second screen may also include a display of one or more additional metrics determined using an ECG signal obtained by the processor 52 (which may be an ECG signal different from the ECG signal used to determine the VAT displayed in the first screen) and / or determined using the received EGM signal. The one or more additional metrics displayed in the second screen may or may not be displayed in the first screen. One or more additional metrics may be displayed for confirming CSP capture, appropriate electrode position, and / or non-RBB block QRS morphology associated with CSP. It should be understood that the "first" screen and the "second" screen of the GUI do not necessarily need to be discrete, separate screens. The first screen and the second screen may be adjacent and may be displayed side by side. In other examples, the GUI may be displayed in a scrolling manner such that the first screen and the second screen may be in a continuous scrolling display of signals and data, wherein a secondary metric is added to the display of the VAT when the VAT meets a threshold difference and / or is less than a threshold VAT.

[0173] It should be understood that, according to the examples, certain actions or events of any of the methods described herein may be performed in parallel in different orders, may be added, merged, or omitted entirely (e.g., not all described actions or events are necessary for practicing the methods). In addition, in some examples, actions or events may be performed simultaneously, for example, by multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially. In addition, for the purpose of clarity, although certain aspects of the present disclosure are described as being performed by a single processor, circuit, or unit, it should be understood that the techniques of the present disclosure may be performed by a combination of processors, units, or circuits associated with, for example, a medical device system.

[0174] In one or more examples, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or codes on a computer-readable medium and executed by one or more hardware-based processing units. A computer-readable medium may include a computer-readable storage medium, which corresponds to a tangible medium, such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and can be accessed by a computer).

[0175] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuit systems. Thus, the term "processor" as used herein may refer to any of the foregoing structures or any other structure suitable for implementing the techniques described herein. Additionally, these techniques may be fully implemented in one or more circuits or logic elements.

[0176] Thus, the medical device systems have been presented in the foregoing description with reference to specific examples. It should be understood that the various aspects disclosed herein may be combined in combinations different from the specific combinations presented in the drawings. It should be understood that various modifications may be made to the referenced examples without departing from the scope of the present disclosure and the following claims.

Claims

1. A medical device, comprising: A processor, the processor being configured to: To obtain one or more electrocardiogram (ECG) signals: For each pacing pulse in the multiple pacing pulses: determining a ventricular activation time using a first ECG signal of the one or more ECG signals; determining a difference between the ventricular activation time and a previously determined ventricular activation time; as well as determining when the difference satisfies a threshold difference; and A display unit is in communication with the processor and is configured to: displaying at least one ECG signal of the one or more ECG signals; displaying at least one of the determined ventricular activation time or the determined difference; as well as In response to determining that the threshold difference is met, a prominent indicator is displayed.

2. The medical device according to claim 1, wherein the processor is further configured to obtain the first ECG signal by: receiving four input signals from a reference electrode and each of three chest electrodes, the three chest electrodes including a left chest electrode and a right chest electrode; determining a center terminal signal according to the four input signals; and A first unipolar ECG signal is determined as a difference between an input signal from the left chest electrode and the center terminal signal.

3. The medical device according to claim 2, wherein the processor is further configured to obtain the first ECG signal by: determining a second unipolar ECG signal based on the input signal; and The first ECG signal is determined to be a bipolar ECG signal by determining a difference between the first unipolar ECG signal and the second unipolar ECG signal.

4. The medical device according to claim 2, wherein: The processor is further configured to obtain the one or more ECG signals by determining a second unipolar ECG signal as a difference between an input signal from the right chest electrode and the center terminal signal; and The display unit is also configured to display a plurality of cardiac cycles of the second unipolar ECG signal, the plurality of cardiac cycles corresponding to at least a portion of the plurality of pacing pulses and being temporally aligned with respective ventricular activation times determined for at least the portion of the plurality of pacing pulses.

5. A medical device according to claim 1, 2, 3 or 4, wherein the processor and the display unit are further configured to simultaneously display multiple cardiac cycles and multiple determined ventricular excitation times of at least one ECG signal among the obtained ECG signals, wherein the multiple cardiac cycles and the multiple ventricular excitation times of the at least one ECG signal among the obtained ECG signals correspond to at least a portion of the multiple pacing pulses.

6. A medical device according to any one of claims 1, 2, 3 or 4, wherein the processor and the display unit are further configured to continuously display each of a plurality of cardiac cycles of at least one of the obtained ECG signals, each of the plurality of cardiac cycles being displayed one at a time individually together with a corresponding determined ventricular excitation time, and the plurality of cardiac cycles corresponding to at least a portion of the plurality of pacing pulses.

7. The medical device according to claim 1, wherein: The processor is further configured to determine each of the ventricular activation times by: identifying a reference point of the first ECG signal following a corresponding one of the plurality of pacing pulses; as well as determining the ventricular activation time as a time interval from a corresponding one of the plurality of pacing pulses to the reference point; and The display unit is further configured to display the first ECG signal and a visual marking of at least one of the identified fiducial points of the first ECG signal together with the determined ventricular activation time.

8. The medical device according to claim 1, wherein: The processor is further configured to determine when a ventricular activation time of the determined ventricular activation times is greater than a threshold ventricular activation time; and The display unit is also configured to display each of the ventricular excitation times that is determined to be greater than the threshold ventricular excitation time according to a first format, and each of the ventricular excitation times that is less than the threshold ventricular excitation time according to a second format different from the first format.

9. The medical device according to claim 1, wherein: The processor is further configured to: obtaining the one or more ECG signals by receiving a plurality of input signals from at least a right chest electrode, a left chest electrode, and a reference electrode, the one or more ECG signals including the first ECG signal associated with the left chest electrode and a second ECG signal associated with the right chest electrode; determining a QRS width for at least one pacing pulse of the plurality of pacing pulses using the second ECG signal; and The display unit is further configured to display the determined QRS width.

10. The medical device of claim 1, wherein: The processor is further configured to: obtaining the one or more ECG signals by receiving a plurality of input signals from at least a right chest electrode, a left chest electrode, and a reference electrode, the plurality of ECG signals including the first ECG signal associated with the left chest electrode and a second ECG signal associated with the right chest electrode; determining, for at least one of the plurality of pacing pulses, using the second ECG signal, at least one of a QRS area, a peak interval of a maximum peak between the first ECG signal and the second ECG signal, or a QRS morphology metric; and The display unit is also configured to display at least one of the QRS area, the peak interval, or the QRS morphology metric.

11. The medical device according to claim 1, wherein the display unit is further configured to display the conspicuous indicator by at least one of: generating a visual notification, generating an auditory notification, adjusting the format of the determined ventricular excitation time to be different from the previously displayed ventricular excitation time, and / or adjusting the background of the determined ventricular excitation time.

12. The medical device of claim 1, further comprising a pulse generator configured to deliver the plurality of pacing pulses via a conduction system pacing electrode.

13. The medical device of claim 1 , further comprising a telemetry circuit configured to receive a conduction system pacing pulse marker signal from an implantable medical device, the implantable medical device configured to deliver the plurality of pacing pulses as conduction system pacing pulses.

14. The medical device of claim 13, wherein the telemetry circuit is further configured to receive electrocardiogram signals from the implantable medical device, the implantable medical device being configured to deliver the plurality of pacing pulses as conducted system pacing pulses; and The display unit is further configured to display the electrocardiogram signal.

15. A method comprising: obtaining one or more electrocardiogram (ECG) signals; For each pacing pulse in the multiple pacing pulses: determining a ventricular activation time using a first ECG signal of the one or more ECG signals; determining a difference between the ventricular activation time and a previously determined ventricular activation time; as well as determining when the difference satisfies a threshold difference; displaying at least one ECG signal of the one or more ECG signals; displaying at least one of the determined ventricular activation time or the determined difference; as well as In response to determining that the threshold difference is met, a prominent indicator is displayed.

16. The method of claim 15, wherein obtaining the first ECG signal comprises: receiving four input signals from a reference electrode and each of three chest electrodes, the three chest electrodes including a left chest electrode and a right chest electrode; Determine a central terminal signal according to the four input signals; as well as A first unipolar ECG signal is determined as a difference between an input signal from the left chest electrode and the center terminal signal.

17. The method of claim 16, wherein obtaining the first ECG signal further comprises: determining a second unipolar ECG signal based on the input signal; as well as The first ECG signal is determined to be a bipolar ECG signal by determining a difference between the first unipolar ECG signal and the second unipolar ECG signal.

18. The method according to claim 16, further comprising: obtaining the one or more ECG signals by determining a second unipolar ECG signal as a difference between an input signal from the right chest electrode and the center terminal signal; as well as A plurality of cardiac cycles of the second unipolar ECG signal are displayed, the plurality of cardiac cycles corresponding to at least a portion of the plurality of pacing pulses and aligned in time with respective ventricular activation times determined for at least the portion of the plurality of pacing pulses.

19. The method according to claim 15, 16, 17 or 18 further includes simultaneously displaying multiple cardiac cycles and multiple determined ventricular excitation times of at least one ECG signal among the obtained ECG signals, wherein the multiple cardiac cycles and the multiple ventricular excitation times of the at least one ECG signal among the obtained ECG signals correspond to at least a portion of the multiple pacing pulses.

20. According to the medical device according to claim 15, 16, 17 or 18, the method also includes continuously displaying each of a plurality of cardiac cycles of at least one of the obtained ECG signals, each of the plurality of cardiac cycles being displayed one at a time individually together with the corresponding determined ventricular excitation time, and the plurality of cardiac cycles corresponding to at least a portion of the plurality of pacing pulses.

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