阅读说明：本技术 用于确定希氏束起搏捕获的医疗装置系统和方法 (Medical device system and method for determining bundle of his pacing capture ) 是由 S·高希 于 2020-02-17 设计创作，主要内容包括：在医疗装置系统中,计算机设备被配置为从包括多个外部电极的电极设备接收体表电信号。所述计算设备在希氏束起搏脉冲的递送期间从所述体表电信号生成电不同步性数据,并且基于所述电不同步性数据来识别有效希氏束捕获。所述计算设备响应于识别所述有效希氏束捕获而生成希氏束捕获的指示。(In the medical apparatus system, the computer device is configured to receive body surface electrical signals from an electrode device comprising a plurality of external electrodes. The computing device generates electrical dyssynchrony data from the body surface electrical signals during delivery of the bundle of his pacing pulses, and identifies a valid bundle capture based on the electrical dyssynchrony data. The computing device generates an indication of his bundle capture in response to identifying the valid his bundle capture.)

1. A medical device system, comprising:

an electrode device comprising a plurality of external electrodes configured to monitor a plurality of body surface electrical signals of a patient; and

a computing device coupled to the electrode device and containing processing circuitry configured to:

generating cardiac electrical dyssynchrony data from the body surface electrical signals received from the plurality of external electrodes during delivery of bundle of his pacing pulses;

identifying, by the his bundle pacing pulse, an effective his bundle capture based on the electrical dyssynchrony data, wherein the effective his bundle capture includes capture of both a left bundle branch and a right bundle branch of a his bundle; and

generating an indication of a his bundle acquisition in response to identifying the valid his bundle acquisition.

2. The system of claim 1, further comprising a his bundle pacing device, the his bundle pacing device comprising:

sensing circuitry configured to sense cardiac electrical signals;

a therapy delivery circuit configured to deliver the his bundle pacing pulse; and

a control circuit coupled to the sensing circuit and the therapy delivery circuit and configured to:

receiving a communication signal corresponding to the indication of the his bundle capture generated by the computing device;

determining a characteristic of the cardiac electrical signal in response to receiving the communication signal; and

establishing a capture detection threshold based on the determined characteristic of the cardiac electrical signal.

3. The system of claim 2, wherein the control circuitry is further configured to control the therapy delivery circuitry to maintain effective his bundle capture by:

determining the characteristic of the cardiac electrical signal received from the sensing circuit after a his bundle pacing pulse delivered by the therapy delivery circuit;

comparing the feature to the established capture detection threshold; and

adjusting a pacing control parameter used by the therapy delivery circuit to deliver the his bundle pacing pulse in response to the feature not satisfying the established capture detection threshold.

4. The system of claim 2 or 3, wherein the computing device is configured to generate the notification by transmitting a wireless signal,

the his bundle pacing apparatus includes a telemetry circuit configured to receive the wireless signal directly from the computing device.

5. The system of any one of claims 2 to 4, wherein the control circuitry is configured to determine the characteristic of the cardiac electrical signal by determining at least one of:

QRS width, QRS area, QRS polarity, QRS morphology and QRS time delay from the his bundle pacing pulse.

6. The system of any of claims 1-5, wherein the computing device is further configured to:

generating baseline electrical dyssynchrony data in the absence of a his bundle pacing pulse; and

identifying bundle capture by comparing the electrical dyssynchrony data generated during delivery of bundle of his pacing pulses to the baseline electrical dyssynchrony data.

7. The system of claim 6, wherein the baseline electrical dyssynchrony data is generated during delivery of pacing pulses that capture ventricular myocardium without capturing the his bundle.

8. The system of any of claims 1-7, wherein the computing device is configured to:

generating electrical asynchrony data by:

determining an electrical activation time from a plurality of QRS waveforms received from the electrode device, an

Determining a measure of the electrical activation time; and

identifying the effective his beam capture by comparing the measure of the electrical activation time to a threshold.

9. The system of any of claims 1-8, wherein the computing device is further configured to:

generating electrical asynchrony data by:

determining a right ventricular measure of electrical activation time from a first plurality of QRS waveforms received from the electrode device corresponding to body surface electrical signals received along the patient's right side, an

Determining a left ventricular measure of electrical activation time from a second plurality of QRS waveforms of the body surface electrical signal received from an external electrode of the electrode apparatus along the left side of the patient; and

identifying a valid bundle of his capture by:

comparing the right ventricular metric and the left ventricular metric to respective right and left bundle branch capture thresholds; and

identifying a valid bundle capture in response to both the right ventricular metric satisfying the respective right bundle branch capture threshold and the left ventricular metric satisfying the left bundle branch capture threshold.

10. The system of any of claims 1-9, wherein the computing device is further configured to:

based on an analysis of the generated electrical dyssynchrony data, distinguishing at least two different types of his bundle captures from a selective his bundle capture, a non-selective his bundle capture, a ventricular-only myocardium capture, a right bundle branch capture, and a left bundle branch capture; and

a notification corresponding to the differentiated type of his bundle acquisition is generated.

11. The system of any one of claims 1 to 10, wherein the electrode apparatus includes an electrode array coupled to a substrate configured to enclose the torso of the patient.

Technical Field

The present disclosure relates to medical device systems and methods for determining the acquisition of the his bundle and establishing a his bundle acquisition detection threshold.

Background

During Normal Sinus Rhythm (NSR), the heartbeat is modulated by electrical signals generated by the Sinoatrial (SA) node located in the right atrial wall. Each atrial 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 responds by propagating a ventricular depolarization signal through the hilgar bundle of the ventricular septum and thereafter to the bundle branches of the right and left ventricles and the purkinje muscle fibers.

Patients with abnormalities in the conduction system, such as AV node poor conduction or SA node dysfunction, may receive pacemakers to restore a more normal heart rhythm and AV synchrony. Ventricular pacing may be performed to maintain a ventricular rate in a patient 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, e.g., in the apex of the right ventricle. The pacemaker itself is typically implanted in a subcutaneous pocket, where the transvenous ventricular lead is tunneled to the subcutaneous pocket.

Dual chamber pacemakers are available that include 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. Dual-chamber pacemakers sense atrial and ventricular electrical signals and may provide both atrial and ventricular pacing as needed to promote normal atrial and ventricular rhythms and to promote AV synchrony in the presence of AV nodes or other conduction abnormalities.

Ventricular pacing using conventional transvenous leads at the right ventricular apex to position the endocardial electrode near the right ventricular apex has been found to be associated with increased risk of atrial fibrillation and heart failure. Alternative pacing sites, such as pacing of the his bundle, have been studied or proposed. Cardiac pacing of the his bundle has been proposed to provide ventricular pacing along the natural conduction system of the heart in patients with conduction defects above the his bundle (e.g., with AV conduction block). Pacing the ventricle via the his bundle allows cardioversion along the natural conduction system of the heart (including the purkinje fibers) and is assumed to promote more physiological normal electrical and mechanical synchrony than other pacing sites, such as the ventricular apex.

Disclosure of Invention

The techniques of the present disclosure generally relate to establishing a his bundle capture detection threshold for detecting capture of the his bundle during cardiac pacing, for example, by an implantable pacemaker configured as a his bundle pacing device. A medical apparatus system comprising an electrode device for sensing a body surface cardiac electrical signal and a computing device for receiving the cardiac electrical signal is configured to determine at least one measure of electrical asynchrony of ventricular depolarizations during his bundle pacing. Evaluation of electrical dyssynchrony by the computing device is used to verify effective his bundle capture based on a relatively low electrical dyssynchrony metric, indicating capture and conduction along the intrinsic ventricular conduction system (including both the right bundle branch and the left bundle branch). The his bundle pacing device is configured to deliver his bundle pacing pulses and sense a cardiac electrical signal to determine characteristics of a QRS waveform of the cardiac electrical signal received by the his bundle pacing device. When valid his bundle capture is verified by the computing device based on the measure of ventricular asynchrony, the his bundle pacing apparatus establishes a his bundle capture detection threshold based on the determined values of the QRS waveform features. A his bundle pacing device operating in accordance with the techniques disclosed herein delivers his bundle pacing and monitors his bundle capture by determining features of the QRS waveform of the cardiac electrical signal and comparing the features to established his bundle capture detection thresholds. The his bundle pacing device may adjust cardiac pacing control parameters based on the capture monitoring to maintain capture of the his bundle.

In one example, the present disclosure provides a medical device system including an electrode apparatus having a plurality of external electrodes configured to monitor body surface electrical signals of a patient and a computing apparatus coupled to the electrode apparatus. The computing device includes processing circuitry and is configured to generate cardiac electrical dyssynchrony data from body surface electrical signals received from the external electrodes during delivery of the bundle pacing pulses, and identify valid capture dyssynchrony data by the bundle pacing pulses based on the electrical dyssynchrony data. The effective his bundle capture includes capture of both the left and right bundle branches of the his bundle. The computing device is further configured to generate an indication of his bundle capture in response to identifying a valid his bundle capture.

In another example, the present disclosure provides a method performed by a medical device system. The method includes receiving, by a computing device, a body surface electrical signal from an electrode device having a plurality of external electrodes, generating, by the computing device, electrical asynchrony data during delivery of the his bundle pacing pulses, and identifying a valid his bundle capture based on the electrical asynchrony data. The method also includes generating, by the computing device, an indication of the his bundle capture in response to identifying the valid his bundle capture.

In yet another example, the present disclosure provides a non-transitory computer-readable storage medium containing a set of instructions that, when executed by a processor of a computing device, cause the computing device to receive a body surface electrical signal from an electrode device having a plurality of external electrodes, generate electrical dyssynchrony data from the body surface electrical signal received from the external electrodes during delivery of a his bundle pacing pulse, and identify effective his bundle capture based on the electrical dyssynchrony data. The instructions also cause the computing device to generate an indication of his bundle capture in response to identifying a valid his bundle capture.

The details of one or more aspects of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages described in the disclosure will be apparent from the description and drawings, and from the claims.

Drawings

Fig. 1 is a conceptual diagram of a medical device system including a his bundle pacing device capable of pacing and sensing in a patient's heart.

Fig. 2 is a conceptual diagram of a leadless intracardiac pacemaker configured as a his bundle pacing device.

Fig. 3 is a schematic diagram of circuitry that may be packaged within a his bundle pacing device configured to perform his bundle pacing and capture detection, according to one example.

FIG. 4 is a conceptual diagram of a medical device system including a computer apparatus for generating electrical activation information of a patient's heart during Hill bundle pacing by a Hill bundle pacing device.

Fig. 5 is a conceptual diagram of the electrode apparatus of fig. 4 according to another example.

Fig. 6 is a flow diagram of a method of identifying his bundle capture by the computing device of fig. 4 during his bundle pacing according to one example.

Figure 7 depicts a method of determining the electrical activation time from at least one QRS waveform of a given surface potential signal received from the electrodes of the electrode apparatus of figure 4 or figure 5.

Fig. 8 is a flow chart of a method for establishing a capture detection threshold performed by the system of fig. 4 in conjunction with a his bundle pacing device, according to one example.

Fig. 9 is a diagram of cardiac electrical signals that may be produced by a his bundle pacing device.

Fig. 10 is a flow diagram of a method for monitoring and maintaining bundle capture by a bundle of his pacing device delivering bundle pacing therapy, according to one example.

Detailed Description

A medical device system for delivering his bundle pacing and detecting and monitoring capture of the his bundle is described herein. When an electrical pacing pulse delivers sufficient electrical energy to cause depolarization of cardiac tissue, the cardiac tissue is "captured". Depolarization of cardiac tissue is sometimes referred to as an electrical "evoked response," followed by mechanical contraction of the ventricle(s). In order to effectively capture and pace the heart to achieve a desired therapeutic effect, cardiac pacing pulses need to have a pulse energy equal to or greater than the capture threshold of cardiac tissue at the pacing site. A pacing capture threshold test may be performed to determine a minimum pacing pulse voltage amplitude for a given pacing pulse width (or minimum pulse width for a given voltage amplitude) that elicits an evoked response. Determination of the pacing capture threshold enables proper programming of the pacing pulse amplitude and pulse width to promote efficient pacing and avoid loss of capture. Capture monitoring by the pacemaker during continuous pacing allows for automatic adjustment of pacing pulse amplitude and/or width to maintain capture when a loss of capture is detected.

Efficient capture of the his bundle by his bundle pacing pulses occurs when the his bundle is captured and induces depolarization that is conducted through the bundle branch system to both the right and left ventricles, thereby increasing electrical synchrony of both the right and left ventricles. An increase in electrical synchrony (or a decrease in electrical asynchrony) of the right and left ventricles is evidenced by a narrowing or relative narrowing of the QRS waveform width of the cardiac electrical signal. Effective bundle capture can occur with or without capture of ventricular myocardial tissue in the vicinity of the bundle pacing electrode. Ineffective bundle capture occurs when bundle capture does not occur or when the bundle is partially captured causing conduction along a portion of the bundle branch system, such as along only the right bundle branch or along only the left bundle branch. Ineffective his bundle capture is evidenced by the broad QRS waveform and may occur with or without nearby ventricular myocardium capture. In some cases, a complete capture loss occurs when the his bundle pacing pulse output is less than both the his bundle capture threshold and the myocardial capture threshold or the intrinsic R-wave is conducted earlier than the his bundle pacing pulse.

When pacing pulses are delivered by electrodes located in the heart to pace the his bundle, it is possible to capture only his bundle tissue, capture both his bundle and peripheral ventricular myocardium, or capture peripheral ventricular myocardium without capturing the his bundle. Capturing only the his bundle may be referred to as "selective" his bundle (SHB) capture. The capture of the his bundle and surrounding ventricular myocardial tissue may be referred to as "non-selective" his bundle (NSHB) capture. Both SHB and NSHB capture may be effective his bundle capture, as conduction along both the right and left bundle branches may cause increased electrical synchrony, as evidenced by the narrow QRS waveform width. A narrow QRS waveform width is a QRS width that is less than a predefined threshold and/or less than a previously determined QRS waveform width when no his bundle pacing is delivered. When no his bundle pacing is delivered, the QRS waveform may appear with an intrinsically conducting R wave or myocardial pacing of the ventricle. In both cases, the QRS waveform is expected to be wider than the effective his bundle pacing period.

Capturing the peripheral ventricular myocardium without capturing the his bundle by his bundle pacing pulses is referred to herein as Ventricular Myocardium (VM) capture and is considered ineffective his bundle capture. In other cases, his bundle pacing is ineffective when only the right bundle branch is captured, only the left bundle branch is captured, or atrial capture occurs instead of the his bundle. Sometimes, fusion may occur when a bundle of his pacing pulses captures the bundle of his and at the same time an intrinsic depolarization occurs. These different types of valid and invalid his bundle capture may cause a change in one or more characteristics of the QRS waveform of the cardiac electrical signal sensed by the his bundle pacing device. Thus, a capture detection threshold is established that distinguishes between QRS waveforms for a valid his bundle capture and invalid his bundle capture as sensed by the his bundle pacing device, enabling the his bundle pacing device to reliably detect valid his bundle capture and provide an appropriate response, e.g., to adjust his bundle pacing therapy, when a valid his bundle capture is not detected.

Disclosed herein are devices and techniques for establishing patient-specific capture detection thresholds applied to features of QRS waveforms by a his bundle pacing apparatus, by which effective his bundle capture can be reliably detected with a high degree of certainty. Reliable detection of effective bundle capture enables the bundle pacing device to adjust pacing pulse output to maintain effective bundle capture, thereby improving the therapeutic effectiveness of bundle pacing. Reliable detection of effective bundle capture may allow the pacemaker to adjust the pacing pulse amplitude to a safety margin greater than the bundle pacing capture threshold while avoiding unnecessarily high pulse output that increases current drain of the pacemaker power supply. Note that as used herein, "his bundle pacing capture threshold" refers to a pacing pulse output or energy, e.g., corresponding to a pacing pulse voltage amplitude and a pacing pulse width, i.e., the minimum pacing pulse output to capture the his bundle. On the other hand, the "his bundle capture detection threshold" is the value of a cardiac electrical signal feature (e.g., a QRS waveform feature, such as QRS waveform width, QRS waveform area, or QRS waveform delay time after a his pacing pulse) that corresponds to efficient capture of the his bundle by a pacing pulse.

Fig. 1 is a conceptual diagram of an Implantable Medical Device (IMD) system 10 capable of pacing and sensing in a patient's heart 8. IMD system 10 includes an IMD14 coupled to a patient's heart 8 via transvenous electrical leads 16, 17, and 18. IMD14 is configured for his bundle pacing and is also referred to herein as a "his bundle pacing device. In the example of fig. 1, IMD14 is a dual-chamber device capable of pacing the Right Atrium (RA) and pacing the ventricle via the his bundle. The housing 15 encloses internal circuitry corresponding to the various circuits and components described below in connection with fig. 3 for sensing cardiac signals from the heart 8, detecting arrhythmias, controlling therapy delivery, and monitoring his bundle capture using the techniques disclosed herein.

IMD14 includes a connector block 12 that may be configured to receive the proximal ends of a RA lead 16, an optional Right Ventricular (RV) lead 17, and a his pacing lead 18, all advanced intravenously for positioning electrodes for sensing and stimulation near the RA, RV, and his bundle, respectively. RA lead 16 is positioned such that its distal end is near the right atrium and superior vena cava. RA lead 16 is equipped with pace and sense electrodes 20 and 22, shown as tip electrode 20 and ring electrode 22 spaced proximally from tip electrode 20. Electrodes 20 and 22 provide sensing and pacing in the right atrium, and are each connected to a respective insulated conductor that extends within the elongated body of RA lead 16. Each insulated conductor is coupled at its proximal end to a connector carried by the proximal lead connector 40.

The his lead 18 is advanced within the right atrium to position the electrodes 32 and 34 near the his bundle for pacing and sensing. The his lead tip electrode 32 may be a helical electrode that is advanced to the inferior extremity of the atrial septum, below the AV node, and near the tricuspid annulus to position the tip electrode 32 in or near the his bundle. The ring electrode 34, which is spaced proximally from the tip electrode 32, may serve as a return electrode, along with the cathode tip electrode 32, for pacing the right and left ventricles via the natural ventricular conduction system extending from the his bundle. Intracardiac Electrogram (EGM) signals may be generated by IMD14 from cardiac electrical signals sensed using tip electrode 32 and ring electrode 34 of his lead 18 and received by sensing circuitry included in IMD 14. As described below, EGM signals generated from cardiac electrical signals received via the his lead 18 may be used to detect the capture of the his bundle and to distinguish between loss of his bundle capture. The electrodes 32 and 34 are coupled to respective insulated conductors extending within the elongated body of the his lead 18, which provide an electrical connection with a proximal lead connector 44 coupled to the connector block 12.

In some examples, IMD14 may optionally be coupled to RV lead 17 for positioning electrodes within the RV to sense RV cardiac signals and deliver pacing or shock pulses in the RV. For these purposes, RV lead 17 is equipped with pacing and sensing electrodes shown as tip electrode 28 and ring electrode 30. RV lead 17 is also shown carrying defibrillation electrodes 24 and 26, which may be elongated coil electrodes for delivering high voltage CV/DF pulses. Defibrillation electrode 24 may be referred to as an "RV defibrillation electrode" or "RV coil electrode" because it may be carried along RV lead 17 such that distal pacing and sensing electrodes 28 and 30 are positioned substantially within the right ventricle when it is positioned for pacing and sensing of the right ventricle. Defibrillation electrode 26 may be referred to as a "Superior Vena Cava (SVC) defibrillation electrode" or "SVC coil electrode" because it may be carried along RV lead 17 such that it is positioned at least partially along the SVC when the distal end of RV lead 17 is advanced within the right ventricle.

Each of the electrodes 24, 26, 28, and 30 is connected to a respective insulated conductor that extends within the body of RV lead 17. The proximal ends of the insulated conductors are coupled to respective connectors, such as a DF-4 connector, carried by proximal lead connector 42 for providing electrical connection to IMD 14. The housing 15 may be used as an active electrode with the RV coil electrode 24 or the SVC coil electrode 26 during CV/DF shock delivery. In some examples, housing 15 may serve as a return electrode for a unipolar sensing or pacing configuration, with any of the electrodes being carried by leads 16, 17, and 18.

It should be appreciated that although IMD14 is illustrated in fig. 1 as an implantable cardioverter defibrillator capable of delivering both low-voltage cardiac pacing therapy and high-voltage cardioversion and defibrillation (CV/DF) shocks, IMD14 may be configured as a dual chamber pacemaker in other examples, coupled only to RA lead 16 and his lead 18, without CV/DF shock delivery capability, and without a third lead, such as RV lead 17. In yet other examples, IMD14 may be a single-chamber device coupled only to his lead 18 for delivering pacing pulses to the ventricle to at least maintain a minimum ventricular rate, thereby eliminating both RA lead 16 and RV lead 17.

External device 50 is shown in telemetric communication with IMD14 via communication link 60. External device 50 may include a processor 52, memory 53, a display unit 54, a user interface 56, and a telemetry unit 58. Processor 52 controls external device operation and processes data and signals received from IMD 14. A display unit 54, which may include a graphical user interface, displays data and other information to the user for viewing parameters of IMD operation and programming, as well as cardiac electrical signals retrieved from IMD 14. Data obtained from IMD14 via communication link 60 may be displayed on display 54. For example, a clinician may view cardiac electrical signals received from IMD14 and/or results of or data derived from his capture threshold testing and monitoring.

User interface 56 may include a mouse, touch screen, keyboard, etc. to enable a user to interact with external device 50 to initiate a telemetry session with IMD14 for retrieving data from and/or transmitting data to IMD14, including programmable parameters for controlling his capture determinations, as described herein. Telemetry unit 58 includes a transceiver and antenna configured for bi-directional communication with telemetry circuitry included in IMD14, and is configured to operate in conjunction with processor 52 for transmitting and receiving data related to IMD functions via communication link 60, which may include data related to his beam capture detection thresholds.

Can be used asA wireless Radio Frequency (RF) link of Wi-Fi or Medical Implant Communication Service (MICS) or other RF or communication frequency bandwidth or communication protocol establishes a communication link 60 between IMD14 and external device 50. Data stored or acquired by IMD14, including physiological signals or associated data derived therefrom, results of device diagnostics, and a history of detected heart rhythm episodes and delivered therapies may be retrieved from IMD14 by external device 50 following an interrogation command.

External device 50 may embody a programmer for use in a hospital, clinic, or physician's office to retrieve data from IMD14 and program operating parameters and algorithms in IMD14 to control IMD functions. The external device 50 may alternatively be embodied as a home monitor or a handheld device. External device 50 may be used to program cardiac signal sensing parameters, rhythm detection parameters, and therapy control parameters used by IMD 14. As described below in connection with fig. 4, the external apparatus 50 may be embodied as a computing device coupled to the electrode device for analyzing the body surface cardiac electrical signals to identify an effective his bundle capture by the IMD 14. In other examples, external apparatus 50 communicates with the computing device of fig. 4 for transmitting a notification of an effective his bundle capture to IMD 14.

Fig. 2 is a conceptual diagram of a leadless intracardiac pacemaker 100 configured as a his bundle pacing device. Pacemaker 100 is shown positioned within the RA for providing ventricular pacing via the his bundle. Pacemaker 100 may include a distal tip electrode 102 extending away from a distal end 112 of pacemaker housing 105. The intracardiac pacemaker 100 is configured to be implanted in the RA of the patient's heart 8 to place the distal tip electrode 102 for delivering pacing pulses to the his bundle. For example, the distal tip electrode 102 may be inserted under 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. Distal tip electrode 102 may be a helical electrode that provides fixation to anchor pacemaker 100 at an implant location. In other examples, pacemaker 100 may include fixation members that include one or more tines, hooks, barbs, spirals, or other fixation member(s) that anchor the distal end of pacemaker 100 at the implant 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 a tissue site that includes a portion of the his bundle. One or more housing-based electrodes 104 and 106 may be carried on a surface of the housing of pacemaker 100 near or at the proximal end 110 of pacemaker 100. Pacing of the his bundle may be achieved using the distal tip electrode 102 as a cathode electrode and either of the housing-based electrodes 104 and 106 as a return anode.

Cardiac electrical signals produced by the heart 8 may be sensed by the pacemaker 100 using a sensing electrode pair selected from electrodes 102, 104 and 106. For example, near field signals may be sensed using the distal tip electrode 112 and the proximal housing-based electrode 104. The second electrical signal may be sensed as a relative far-field signal using electrodes 104 and 106. One or both of the near-field and far-field cardiac electrical signals may be analyzed to determine his bundle capture and distinguish between valid and invalid his bundle captures or loss of capture according to the techniques disclosed herein.

Fig. 3 is a schematic diagram of circuitry that may be packaged within a his bundle pacing device configured to perform his bundle pacing and capture detection, according to one example. For ease of illustration, the block diagram of fig. 3 represents the IMD14 of fig. 1, but it should be understood that due to the functionality of the various circuits and components shown in fig. 3 for performing his bundle pacing and detection and differentiation of valid and invalid his bundle captures, it may be similarly implemented in the intracardiac pacemaker 100 of fig. 2 in other types of capture and/or capture loss, and generally relates to a his bundle pacing device capable of delivering his bundle pacing pulses, sensing cardiac electrical signals, and detecting his bundle captures in accordance with the techniques disclosed herein.

Housing 15 is represented as the electrodes used for sensing and delivery of cardiac electrical stimulation pulses in fig. 3. The electronic circuitry enclosed within housing 15 includes software, firmware, and hardware that cooperate to monitor cardiac electrical signals, determine when pacing therapy is needed, and deliver pacing electrical pulses to the patient's heart as needed according to programmed pacing modes and pacing pulse control parameters. The electronic circuitry includes control circuitry 80, memory 82, therapy delivery circuitry 84, sensing circuitry 86, telemetry circuitry 88, and power supply 98.

Power supply 98 optionally provides power to the circuitry of IMD14, 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. The connections between the power supply 98 and each of the other components 80, 82, 84, 86 and 88 will be understood from the general block diagram of fig. 3, but are not shown for clarity. For example, the power source 98 may be coupled to one or more charging circuits included in the therapy delivery circuit 84 for providing the power required to charge a holding capacitor included in the therapy delivery circuit 84 that discharges at the appropriate time for delivering pacing pulses under the control of the control circuit 80. The power supply 98 may also be coupled to components of the sensing circuitry 86 (e.g., sense amplifiers, analog-to-digital converters, switching circuitry, etc.), the telemetry circuitry 88, and the memory 82 to provide power to the various circuits as needed.

The functional blocks shown in fig. 3 represent functionality included in the his bundle pacing apparatus, and may include any discrete and/or integrated electronic circuit components implementing analog and/or digital circuits capable of producing the functionality attributed herein to the his bundle pacing apparatus. Various components may include an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group) and memory that execute one or more software or firmware programs, a combinational logic circuit, a state machine, or other suitable components or combinations of components that provide the described functionality. Given the disclosure herein, it is within the ability of one 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.

Control circuitry 80 may communicate with therapy delivery circuitry 84 and sensing circuitry 86, e.g., via a data bus, to sense cardiac electrical signals and control delivery of cardiac electrical stimulation therapy in response to sensed intrinsic cardiac events (e.g., P-waves attendant to atrial depolarization and R-waves attendant to ventricular depolarization, or the absence thereof). The available electrodes 20, 22, 24, 26, 28, 30, 32, 34 and the housing 15 are electrically coupled to therapy delivery circuitry 84 for delivering electrical stimulation pulses to the patient's heart and/or sensing circuitry 86 for sensing cardiac electrical signals generated by the heart, including intrinsic signals generated by the heart in the absence of stimulation pulses and evoked response signals generated by the heart in response to the delivered stimulation pulses.

Sensing circuitry 86 may include two or more sensing channels for sensing cardiac electrical signals from two or more sensing electrode vectors. For example, electrodes 20 and 22 may be used to sense the RA signal, electrodes 28 and 30 may be used to sense the RV signal, and electrodes 32 and 34 may be used to sense the his signal. In other examples, as shown in fig. 3, the his bundle near-field signal may be sensed by one sensing channel, as shown by near-field sensing channel 84, for example using electrodes 32 and 34 of the his lead 18. The far-field signal may be sensed by a second sensing channel, as illustrated by far-field sensing channel 89.

As used herein, a "near-field" signal refers to a cardiac electrical signal received from a sensing electrode vector that includes at least one electrode located near the his bundle or near the his bundle, his pacing pulse delivery site, such that the near-field signal may also be referred to as a "his bundle near-field signal. The his-beam near-field signal may or may not include the his-beam evoked response, depending on whether the his-beam is captured or not. The his bundle near-field signal may comprise an evoked response QRS waveform signal resulting from an active his bundle acquisition and an inactive his bundle acquisition that may be conducted along only a portion of the bundle branch system. The his bundle near-field signal may also include evoked response QRS waveform signals caused by VM capture and loss of his bundle capture.

As used herein, a "far-field" signal refers to a cardiac electrical signal received from a pair of electrodes including at least one electrode that is relatively farther from the his bundle than an electrode vector used to sense his bundle near-field signals and/or an inter-electrode distance between two electrodes defining a far-field sensing electrode vector is greater than an inter-electrode distance between two electrodes defining a his bundle near-field sensing electrode vector. Far-field signals are more representative of global activation of the ventricles, while near-field signals are more representative of local tissue activation at or near the pacing site. The far-field signal may comprise an evoked response QRS waveform signal associated with either a valid his bundle capture (which may be either SHB capture or NSHB capture) or an invalid his bundle capture, such as causing conduction along only a portion of the bundle branch system during partial his bundle capture, during VM capture where his bundle capture is lost, or during complete loss of capture of the his bundle pacing pulse. In the latter case, the QRS waveform signal sensed by far-field sensing channel 89 or near-field sensing channel 87 may be an intrinsic R-wave or evoked response from a ventricular pacing pulse delivered by RV pacing electrodes 28 and 30.

When the his bundle is effectively captured, the far-field QRS wave width is expected to be narrower than when the his bundle is not effectively captured (and ventricular myocardial tissue or only a portion of the conduction system, e.g., only the right bundle branch, is captured). Causing effective capture of the conductive his bundle via the intrinsic ventricular conduction system that includes both the right and left bundle branches generally promotes increased synchrony of the right and left ventricular electrical activation times. This increased synchronicity is associated with a narrower far-field QRS width. The relatively wide QRS wave width is associated with increased asynchrony or heterogeneity in the right and left ventricular electrical activation times. A wider QRS wave width may occur when the his bundle is not captured at all or only partially captured such that conduction along only a portion of the bundle branch conduction system or depolarization is conducted along a different pathway than the normal intrinsic ventricular conduction system.

In some examples, far-field signals may be sensed using electrodes carried by RA lead 16 and IMD housing 15 (e.g., electrode 20 and housing 15 or electrode 22 and housing 15). In examples including RV lead 17, far-field signals may be sensed using RV coil electrode 24 paired with housing 15, SVC coil electrode 26 paired with housing 15, or RV coil electrode 24 paired with SVC coil electrode 26. The bundle of his detection method disclosed herein includes detecting bundle of his capture, and may include distinguishing between a valid bundle of his capture and an invalid bundle of his capture or a missing bundle of his capture using a capture detection threshold established based on a ventricular asynchrony metric, as described below.

The sensing circuitry 86 may include switching circuitry for selectively coupling pairs of near-field sensing electrodes from the available electrodes to the near-field sensing channel 87 for sensing near-field his beam signals and for selectively coupling pairs of far-field sensing electrodes to the far-field sensing channel 89 for sensing far-field electrical signals relative to the site at which the his beam pacing pulses are delivered. The far-field sensing electrode pair may exclude at least one or both of the electrodes used to deliver the his bundle pacing pulse. The switching circuitry may include a switch array, switch matrix, multiplexer, or any other type of switching device suitable for selectively coupling components of sensing circuit 86 to selected electrodes.

Each of the near-field sensing channel 87 and far-field sensing channel 89 may include an input filter for receiving cardiac electrical signals from a respective pair of sensing electrodes, a preamplifier, an analog-to-digital converter, and a band-pass filter for generating a multi-bit digital EGM signal for detecting his-beam captures and distinguishing between at least valid his-beam captures and invalid his-beam captures (including complete missing captures of his-beam), and may distinguish between SHB, NSHB, and VM captures, and/or other types of valid and invalid captures, such as right-beam branch captures, left-beam branch captures, and fusion. The characteristics of the near-field and far-field EGM signals may be determined by the control circuit 80, and in some examples, each of the sensing channels 87 and 89 may include a rectifier to produce a rectified signal from which the control circuit 80 may determine signal characteristics for determining his beam capture. As described below, the QRS waveform following the his bundle pacing pulse can be used to detect both valid and invalid his bundle captures. The QRS waveform following the capture of the his bundle and/or his bundle pacing pulses of the ventricular myocardium may also be referred to herein as an "evoked response signal" and includes an evoked response R-wave that may be sensed by the sensing circuitry 86.

The sensing circuitry 86 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 sensing circuitry 86 for detecting intrinsic P-waves accompanying intrinsic atrial depolarization using one or both of electrodes 20 and 22 carried by RA lead 16. A ventricular event detector may be included in sensing circuitry 86 for detecting intrinsic R-waves 17 accompanying intrinsic ventricular depolarization using electrodes 32 and 34 carried by the his lead 18 and/or using electrodes 24, 26, 28, and/or 30 carried by the RV lead. Cardiac event sensing thresholds, such as P-wave sensing thresholds or R-wave sensing thresholds, may be automatically adjusted by sensing circuitry 86 under the control of control circuitry 80 based on timing intervals and sensing thresholds determined by control circuitry 80, stored in memory 82, and/or controlled by hardware, firmware, and/or software of control circuitry 80 and/or sensing circuitry 86.

Upon detecting a cardiac electrical event based on a sensing threshold crossing, the sensing circuitry 86 may generate a sensed event signal that is communicated to the control circuitry 80. For example, the atrial event detector may generate a P-wave sensed event signal in response to a P-wave sensing threshold crossing. The ventricular event detector may generate an R-wave sensed event signal in response to the R-wave sensing threshold crossing. The sensed event signals are used by control circuitry 80 to set an escape interval timer that controls the basic time interval for scheduling cardiac pacing pulses. Control circuitry 80 may include various timers or counters for counting down AV pacing intervals, VV pacing intervals, AA pacing intervals, and the like. The sensed event signals may trigger or inhibit a pacing pulse depending on the particular programmed pacing mode. For example, a P-wave sensed event signal received from sensing circuitry 86 may cause control circuitry 80 to inhibit a scheduled atrial pacing pulse and schedule a bundle of his pacing pulses at a programmed AV pacing interval. If the AV pacing interval expires before the control circuit 80 receives the R-wave sensed event signal from the sensing circuit 86, the control circuit 80 may control the therapy delivery circuit 84 to deliver a his pacing pulse at the AV pacing interval after the sensed P-wave and in this manner provide atrial-synchronized ventricular pacing that promotes an increase in ventricular synchrony. If an R-wave sensed event signal is received from sensing circuitry 86 before the AV pacing interval expires, the scheduled Hill pacing pulse may be disabled. The AV pacing interval controls the amount of time between an atrial event (pacing or sensing) and the his bundle pacing pulse to promote AV synchrony and induce ventricular capture via the his purkinje conduction system of the ventricle.

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 switching circuitry that controls when the holding capacitor(s) are charged and discharged across the output capacitor to deliver pacing pulses to a selected pacing electrode vector coupled to therapy delivery circuit 84. Therapy delivery circuitry 84 may include one or more pacing channels. In the example of IMD14, therapy delivery circuitry 84 may include a RA pacing channel, a his bundle pacing channel, and a RV pacing channel, each channel including a holding capacitor, one or more switches, and an output capacitor for producing pacing pulses delivered by respective RA lead 16, RV lead 17, and his lead 18. It should be appreciated that where IMD14 is a single-chamber device configured to receive his lead 18, therapy delivery circuitry 84 may include a single pacing channel. Where IMD14 is a dual-lumen device configured to receive RA lead 16 and his lead 18, therapy delivery circuitry 84 may have an atrial pacing channel and a his pacing channel.

Therapy delivery circuit 84 charges the holding capacitor to the programmed pacing voltage amplitude and discharges the capacitor to the programmed pacing pulse width according to the control signal received from control circuit 80. For example, the pacing timing circuitry included in control circuitry 80 may include programmable digital counters set by a microprocessor of control circuitry 80 for controlling basic pacing time intervals associated with various single or multi-chamber pacing modes or anti-tachycardia pacing sequences. The microprocessor of control circuit 80 may also set the amplitude, pulse width, polarity, or other characteristic of the cardiac pacing pulses, which may be based on programmed values stored in memory 82.

The control circuit 80 is configured to perform his bundle capture monitoring by determining one or more characteristics of a QRS waveform of the near-field and/or far-field cardiac electrical signal received from the sensing circuit 86. The QRS feature determined after the his bundle pacing pulse is compared to the established his bundle capture detection threshold to distinguish between valid and invalid his bundle captures and loss of capture. If the QRS feature meets the acquisition detection threshold requirement, a valid bundle acquisition is detected. If not, an ineffective capture of the his bundle may be detected, which may include a loss of his bundle capture or only a partial capture of the his bundle conduction system. The control circuit 80 may control the therapy delivery circuit 84 to adjust the pacing pulse output, e.g., increase the pacing pulse voltage amplitude and/or pulse width, in response to detecting a loss of capture or an ineffective his bundle capture in order to maintain effective his bundle capture and facilitate improved electrical synchrony of the right and left ventricles.

The appropriate capture detection threshold applied by the control circuit 80 to the QRS waveform feature to detect effective his bundle capture may vary between the patient, the electrode position, the sensing electrode vector (e.g., near field or far field, etc.), the his bundle pacing system, and other factors. In some cases, changes in the EGM signal produced by the his bundle pacing device due to an effective his bundle capture may be difficult to distinguish from an ineffective his bundle capture (particularly from a relatively near-field signal) which may not fully reflect the increase in overall electrical homogeneity or synchrony of the right and left ventricles following an effective his bundle pacing pulse. The techniques disclosed herein provide, in conjunction with fig. 4, an external computing device for identifying a valid his bundle capture with a high degree of certainty from cardiac electrical signals received from body surface electrodes. A his beam pacing apparatus, such as IMD14, is notified that a valid his beam capture is recognized by the computing device and is configured to establish a his beam capture detection threshold in response to the notification. The his bundle acquisition detection threshold may be based on QRS waveform characteristics determined in response to being informed of a confirmed valid his bundle acquisition.

Control parameters used by control circuitry 80 to sense cardiac events and control pacing therapy delivery may be programmed into memory 82 via telemetry circuitry 88. Telemetry circuitry 88 includes a transceiver and antenna for communicating with external device 50 (fig. 1) using radio frequency communication or other communication protocols. Under the control of control circuitry 80, telemetry circuitry 88 may receive downlink telemetry from external device 50 and transmit uplink telemetry to the external device.

In some examples, the telemetry circuitry 88 is configured for two-way radio frequency communication with an external computing device configured to identify his bundle acquisition as described below. In some examples, the telemetry circuitry 88 isAn enabling circuit configured to receive a his bundle capture notification from an external apparatus 50 or other external computing device configured to identify a valid his bundle capture from a body surface cardiac electrical signal, such as an Electrocardiogram (ECG) signal. As described in connection with FIGS. 4-10, IMD14 or pacemaker 100 may be onThe his bundle capture detection threshold for his bundle capture monitoring is established in response to a his bundle capture notification received from the external computing device.

Fig. 4 is a conceptual diagram of a system 200 for evaluating electrical activation information of a patient's heart 8 during his beam pacing by a his beam pacing device, such as IMD14 shown in fig. 1 or pacemaker 100 shown in fig. 2. Although the his bundle pacing device is not seen in the view of fig. 4, it should be understood that the system 200 is used in conjunction with a his bundle pacing device configured to deliver his bundle pacing pulses to the heart 8. The system 200 may be used in conjunction with a his-beam pacing device to establish a his-beam capture detection threshold that is applied to characteristics of cardiac electrical signals received by the his-beam pacing device for monitoring and detecting effective his-beam capture.

System 200 includes electrode device 210, interface/amplifier circuitry 216, and computing device 240. The electrode apparatus 210 includes a plurality of electrodes 212 that may be carried by a patient attachable or wearable substrate 213, for example, a belt that is strapped around the chest or torso of the patient 2. The electrode device 210 is operatively coupled to the computing device 240 via the interface/amplifier circuitry 216 (e.g., via a wired electrical connection, wirelessly, etc.) to provide electrical signals from each of the electrodes 212 to the computing device 240 for analysis to identify his bundle capture. The electrode apparatus 210 may generally correspond to a bioelectric sensor device described in U.S. patent No. 9,320,446 (Gillberg et al) or a surface biopotential sensing device generally described in U.S. patent No. 8,972,228 (Ghosh et al).

The degree of dispersion of electrical activation times of the patient's heart may be evaluated to detect effective his bundle capture by pacing pulses delivered to the heart 8 by a his bundle pacing device (e.g., IMD14 or pacemaker 100). The more heterogeneous or asynchronous the electrical activation time of the patient's ventricle, the less likely it is that the his bundle pacing pulse will effectively capture the his bundle. The time of electrical activation of the ventricles indicating relative homogeneity or synchrony indicates effective his beam capture. The electrode device 210 may be used to monitor or determine alternative electrical activation information or data for one or more regions of the patient's heart. The electrode device 210 may be configured to measure body surface potentials of the patient 2, more specifically torso-surface potentials of the patient 2, also referred to herein as body surface cardiac electrical signals. As shown in fig. 4, the electrode device 210 may include a set or array of electrodes 212 configured on a substrate 213 to wrap around the torso of the patient 2 such that the electrodes 212 surround the heart 8 of the patient. The electrodes 212 may be positioned around the circumference of the patient 2, including the posterior, lateral, posterolateral, anterolateral, and anterior locations of the torso of the patient 2.

The electrode 212 may be electrically connected to interface/amplifier circuitry 216 via a wired connection 218. The interface/amplifier circuitry 216 may be configured to filter and amplify the electrical signals from the electrodes 212 and provide the amplified signals to the computing device 240, e.g., as a data channel. For example, the interface/amplifier circuit 216 may include input filters and amplifiers, analog-to-digital converters, and output amplifiers for generating surface biopotentials or ECG signals from each of the electrodes 212. In some examples, system 200 may include wireless communications for transmitting signals from interface/amplifier circuitry 216 to computing device 240. For example, the interface/amplifier circuitry 216 may be electrically coupled to the computing device 240 by analog electrical connections, digital electrical connections, wireless connections, bus-based connections, network-based connections, internet-based connections, and the like.

Although in the example of fig. 4, the electrode device 210 includes an electrode substrate 213 in the form of a strip or band that may be wrapped around the torso of the patient 2, in other examples, any of a variety of substrates, such as tape, adhesive, vests, jackets, or other substrates, may be used to assist in the spacing, placement, and contact of the electrodes 212 along the torso of the patient around the heart 8. In some examples, the substrate 213 may include an elastic band, a tape strip, or a cloth. In other examples, the electrodes 212 may be placed separately on the torso of the patient 2, for example using an adhesive pad as the electrode substrate. Further, in other examples, the electrodes 212 (e.g., arranged in an array) may be part of or positioned within a patch, vest, and/or other manner of securing the electrodes 212 to the torso of the patient 2.

Fig. 5 is a conceptual diagram of an electrode apparatus 210 according to another example. In this example, a plurality of spaced apart electrodes 212 are carried by a substrate 214 configured as a vest configured to distribute the electrodes 212 along the torso of the patient 2 and to maintain the electrodes 212 in close proximity or direct contact with the skin of the patient for sensing surface biopotential signals caused by the electrical activity of the patient's heart. As shown, the electrodes 212 may be distributed over the torso of the patient 2, including, for example, the anterior, lateral, posterolateral, anterolateral, and posterior surfaces of the torso of the patient 2.

The substrate 214 may be formed of fabric, with the electrodes 212 attached to the fabric. The substrate 214 may be configured to maintain the position and spacing of the electrodes 212 on the torso of the patient 2 and may be marked to help determine the position of the electrodes 212 on the surface of the torso of the patient 2. In one example, the substrate 214 includes 17 or more anterior electrodes positionable proximate the anterior torso of the patient and 39 or more posterior electrodes positionable proximate the posterior torso of the patient. In some examples, there may be about 25 electrodes to about 256 electrodes carried by the substrate 214 to be distributed around the torso of the patient 2, although other configurations may have more or fewer electrodes 212.

As described herein, the electrode device 210 may be configured to measure electrical information (e.g., electrical signals) representative of different regions of the patient's heart. For example, the activation times of different regions of the patient's heart may approximate the activation times determined from the surface potential signals received from the electrodes 212 proximate to the region of the body surface corresponding to the different regions of the patient's heart.

Referring generally to the system 200 shown in fig. 4 and 5, electrodes 212 are carried by a selected substrate configured to surround the heart 8 for recording or monitoring cardiac electrical signals attendant to cardiac depolarization and repolarization after the signals have propagated through the torso of the patient 2. Each of the electrodes 212 may be used in a unipolar configuration to sense torso-surface potentials that reflect cardiac signals. Interface/amplifier circuitry 216 may also be coupled to a return electrode or an indifferent electrode (not shown) that may be used in combination with each electrode 212 for unipolar sensing. In some examples, there may be about 12 to about 50 electrodes 212 spatially distributed around the torso of patient 2. Other configurations may have more or fewer electrodes 212. The size, number, and arrangement of electrodes 212 on substrate 213 or 214 and relative to heart 8 shown in fig. 4 and 5, respectively, are intended to illustrate the concept of an electrode apparatus that may be employed in system 200 without intended limitation.

Computing device 240 may record and analyze electrical signals (e.g., torso-surface potential signals) sensed by electrodes 212 and filtered and amplified by interface/amplifier circuitry 216. The computing device 240 may be configured to analyze the signals from the electrodes 212 to provide front and rear electrode signals and a heart electrical activation time, e.g., representing an actual or local electrical activation time of one or more regions of the patient's heart. For example, the electrical signals received by the electrodes located at the left anterior surface location of the torso of the patient may represent electrical signals of the left anterior left ventricular region of the heart of the patient. The electrical signals received by the electrodes located at the left lateral outside surface of the torso of the patient may represent electrical signals of the left lateral left ventricular region of the heart of the patient. The electrical signals received by the electrodes at the left posterolateral surface location of the patient's torso may represent electrical signals of the posterolateral left ventricular region of the patient's heart. The electrical signals received by the electrodes located at the posterior surface location of the patient's torso may represent electrical signals of the posterior left ventricular region of the patient's heart, among other things.

Bundle of his pacing may provide more synchronous, more homogeneous electrical activation of the right and left ventricles of the heart than pacing from other sites in or on the ventricles, since the depolarization caused by a bundle of his pacing pulses that effectively capture the bundle of his may be conducted through the natural, intrinsic conduction system of the ventricles. Spatial electrical activation of the heart chamber using the system 200 can be performed by the his beam pacing device during his beam pacing to determine with a high degree of certainty when a his beam pacing pulse is effectively capturing the his beam based on a reduction in ventricular asynchrony (also sometimes referred to as "electrical heterogeneity"). This determination is used to notify the his bundle pacing device when a valid his bundle capture is confirmed, so that the his bundle pacing device is able to establish a his bundle capture detection threshold used by the his bundle pacing device for his bundle capture monitoring and distinguishing between valid and invalid his bundle captures.

Using the electrical activity monitored during his bundle pacing at different pacing pulse output settings and/or in the absence of his bundle pacing, a superficial isochron map of ventricular activation can be constructed. The monitored electrical activity and/or ventricular activation map may be used to generate electrical dyssynchrony data. The electrical dyssynchrony data may include a measure of electrical dyssynchrony. A measure of electrical dyssynchrony, which may also be referred to as the measure "electrical heterogeneity", is an indication of the temporal dispersion of the time of electrical activation over the heart chambers. A measure of electrical dyssynchrony may be determined from QRS waveforms of electrical signals received from electrodes 212 that are spatially dispersed over the torso of the patient and the surrounding heart 8. For example, the electrical activation time of the ventricular region may be determined as the time interval from the start of the QRS waveform to the fiducial point of the QRS waveform. In some examples, the electrical activation time is the time from the start of the QRS waveform to the maximum slope of the QRS waveform. For example, the electrical activation time is determined as the time from the start of the QRS waveform to the maximum negative slope of the QRS waveform. An example method for determining the electrical activation time is described below in connection with FIG. 7.

The computing device 240 may be configured to determine a measure of electrical dyssynchrony by determining electrical activation times from each of the cardiac electrical signals received from the electrodes 212, or a selected subset thereof, and determine a Standard Deviation (SDAT) of those electrical activation times. In some examples, a mean and/or standard deviation may be determined from electrical signals received from electrodes on the left side of the patient's torso to obtain a measure of electrical dyssynchrony of the left ventricle. For example, an average value of the Left Ventricular Activation Time (LVAT) may be determined. A measure of LVAT may be determined from electrodes along both the anterior and posterior surfaces of the left side of patient 2. The measure of electrical dyssynchrony may include a measure of the average Right Ventricular Activation Time (RVAT) of electrodes on the right side of the patient's torso. The metric of RVAT may be determined from electrodes on both the anterior and posterior surfaces along the right side of the patient 2. The measure of electrical dyssynchrony may include a Mean Total Activation Time (MTAT) obtained from a plurality of electrode signals on the left and right sides of the patient's torso (from the anterior and/or posterior surfaces of the patient 2), and/or it may include other measures (standard deviation, quartile difference, difference between the latest and earliest activation times, as examples) that correlate with or correspond to a range or spread of activation times sensed by a combined plurality of spaced apart electrodes (including posterior, anterior and/or laterally positioned electrodes) located on the right side of the patient's torso, on the left side of the patient's torso, or on the left and right sides of the patient's torso.

Assessing electrical dyssynchrony of the ventricle during his bundle pacing to establish a capture detection threshold by the his bundle pacing device may include determining at least one of SDAT, LVAT, RVAT, and MTAT. As an example, the computing device 240 may detect a valid his bundle capture in response to a SDAT generated during his bundle pacing that is less than a selected SDAT threshold. As an example, the selected SDAT threshold may be less than or equal to 25 milliseconds (ms) or another selected threshold (which may be patient specific) to distinguish between valid and invalid his bundle acquisitions. When the patient has complete atrioventricular conduction, his bundle pacing may be stopped so that a baseline electrical dyssynchrony metric may be determined when his bundle pacing is stopped. In this case, when SDAT is reduced compared to his bundle-free pacing, e.g., relative changes in SDAT, his bundle capture may be identified. If the patient suffers from AV conduction block and therefore relies on ventricular pacing, a measure of electrical dyssynchrony may be determined during RV pacing (when RV pacing electrodes are available, as with IMD14 of fig. 1). For example, a valid his bundle capture may be identified when the SDAT during his bundle pacing is reduced compared to the SDAT determined during RV pacing.

In other examples, a valid his bundle capture may be detected based on LVAT being below a selected threshold during his bundle pacing. As an example, the selected threshold corresponding to LVAT indicating a valid his bundle capture may be less than or equal to 35 milliseconds. In at least one example, a valid his bundle capture is identified in response to both the SDAT and LVAT generated during his bundle pacing being below a selected threshold. In yet other examples, an effective bundle capture may be detected in response to the RVAT and/or MTAT generated during bundle his pacing therapy being below a selected threshold. In other examples, the his bundle pacing device is configured to deliver his bundle pacing pulses at multiple pacing pulse outputs (e.g., at multiple pacing pulse amplitudes), and the computing apparatus 240 identifies his bundle capture when the SDAT, LVAT, RVAT, and/or MTAT is at a minimum or relatively reduced value as compared to the same metric values obtained during his bundle pacing at different pacing pulse outputs.

Additionally, the computing device 240 may be configured to generate a display or graphical user interface depicting the electrical activation time and/or electrical dyssynchrony data obtained using the electrode device 210. In various examples, computing device 240 may be a server, a personal computer, or a tablet computer, and may include user input device 242 and display device 230. Computing device 240 may be configured to receive input from input device 242 and transmit output to display device 230 (fig. 4). Further, the computing device 240 may include a data store that may allow access to handlers or routines and/or one or more other types of data, for example for driving a Graphical User Interface (GUI) configured to non-invasively identify his bundle capture.

The computing device 240 may be operatively coupled to the input device 242 and the display device 230, for example, to transfer data to and from each of the input device 242 and the display device 230. For example, computing device 240 may be electrically coupled to each of input device 242 and display device 230 using, for example, an analog electrical connection, a digital electrical connection, a wireless connection, a bus-based connection, a network-based connection, an internet-based connection, and so forth. As further described herein, a user may provide input to the input device 242 to manipulate or modify one or more graphical depictions displayed on the display device 230, and to view and/or select one or more pieces of information related to electrically activated data.

Although as depicted, input device 242 is a keyboard, it should be understood that input device 242 may comprise any device capable of providing input to computing device 240 to perform the functionality, methods, and/or logic described herein. For example, the input device 242 may include a mouse, a trackball, a touch screen (e.g., a capacitive touch screen, a resistive touch screen, a multi-touch screen, etc.), and the like. Likewise, the display device 230 may include any device capable of displaying information to a user, such as a graphical user interface 232 including cardiac electrical signal information, textual instructions, graphical or tabular depictions of electrical activation information, graphical depictions of the anatomy of the human heart, graphical depictions of the patient's heart, graphical depictions of the location of one or more electrodes, graphical depictions of the human torso, graphical depictions or graphical depictions of the patient's torso, graphical depictions or actual images of implanted electrodes and/or leads, and the like. Further, the display device 230 may include a liquid crystal display, an organic light emitting diode screen, a touch screen, a cathode ray tube display, and the like.

The data stored and/or used by the computing device 240 may include, for example, electrical signal/waveform data from the electrode device 210, portions or portions of various signals received from the electrode device 210, electrical activation times determined from signals received from the electrode device 210, graphics (e.g., graphical elements, icons, buttons, windows, dialog boxes, drop-down menus, graphical regions, graphical areas, 3D graphics, etc.), graphical user interfaces, results from one or more processing programs or routines employed in accordance with the present disclosure (e.g., electrical dyssynchrony metrics and his bundle capture or non-capture determinations), or any other data necessary for performing one and/or more processes or methods described herein.

The computing device 240 may be configured to generate a notification of his beam capture recognition in response to the electrical activation data satisfying the valid his beam capture detection criteria. The notification may be generated on the display 230 of the computing device 240. The notification may include an audible notification in the form of a beep, tone, voice, or other sound. In some examples, the notification includes a wireless transmission signal indicating his bundle acquisition detection. The his bundle pacing device may be configured, for example, viaOr other wireless connection, receives the transmitted notification directly from the computing device 240. The his bundle pacing device may respond by establishing a his bundle capture detection threshold, as described below in connection with fig. 8.

The computing device 240 may be, for example, any fixed or mobile computer system (e.g., controller, microcontroller, personal computer, microcomputer, tablet computer, etc.) and may generally be described as including processing circuitry. The exact configuration of computing device 240 is not limiting and virtually any device capable of providing suitable computing and control capabilities (e.g., graphics processing, etc.) may be used. Given the disclosure herein, it is within the ability of one skilled in the art to provide software, hardware, and/or firmware to implement the described functionality in the context of any modern medical device system. Thus, the computer language, computer system, or any other software/hardware to be used to implement the processes described herein should not limit the scope of the systems, processes, or programs described herein (e.g., the functionality provided by such systems, processes, or programs). In some examples, functionality attributed to the computing device 240 may be incorporated into the external apparatus 50 of fig. 1, such that a programmer for communicating with the his bundle pacing apparatus to program pacing and sensing control parameters and retrieve data from the his bundle pacing apparatus may be configured to generate electrical dyssynchrony data from signals received from the electrode device 210, detect valid his bundle capture from the electrical dyssynchrony data, and transmit a notification of his bundle capture to the his bundle pacing apparatus.

Fig. 6 is a flowchart 250 of a method for identifying his bundle capture by a computing device 240 during his bundle pacing according to one example. The method of flowchart 250 is performed by system 200 during his beam pacing delivered by a his beam pacing device, such as IMD14 or pacemaker 100. At block 252, the computing device 240 generates electrical dyssynchrony data. The electrical dyssynchrony data may include SDAT, LVAT, RVAT, MTAT, or other measure(s) of time dispersion of ventricular electrical activation resulting from cardiac electrical signals received from the electrode device 210. The computing apparatus 240 may generate electrical dyssynchrony data prior to or concurrently with the suppression of the his bundle pacing by the his bundle pacing device. By generating electrical dyssynchrony data prior to or concurrently with inhibiting his bundle pacing, computing device 240 may generate baseline or his bundle non-captured electrical dyssynchrony data for comparative analysis with electrical dyssynchrony data generated during delivery of his bundle pacing. In a pacing-dependent patient, when his bundle pacing is inhibited to avoid ventricular arrest, RV pacing may be delivered, e.g., using RV lead 17, while generating electrical dyssynchrony data corresponding to his bundle non-capture.

The computing device 240 may generate electrical dyssynchrony data at block 252 by determining an electrical activation time from one or more QRS waveforms for each cardiac electrical signal (or selected subset of cardiac electrical signals) received from the electrode device 210. Fig. 7 is a conceptual diagram of a QRS waveform and a method for determining an electrical activation time that may be performed by computing device 240. In this example, the illustrated QRS waveform 280 is depicted as a net negative going waveform. In various examples, a QRS waveform can be a net negative or net positive complex wave, and can have a region above the baseline signal (positive region) and a region below the baseline signal (negative region). The electrical activation time 284 may be determined as the point in time when the maximum negative slope 283 of the QRS waveform 280 occurs. The electrical activation time 284 may be determined relative to the QRS onset 282. In this example, the electrical activation time 284 may be determined as the time from the QRS onset 282 (considering time 0 msec) to the steepest negative slope 283 of the QRS waveform 280. Accordingly, the computing device 240 may include a differentiator or algorithm for calculating the successive differences between the QRS waveform sampling points to identify the maximum negative slope of the QRS waveform 280, in this example, on the leading portion of the QRS waveform 280, prior to the maximum peak 288.

The QRS onset 282 can be determined by identifying the smallest sampling point of the QRS waveform 280 that precedes the peak 288 but within the QRS time window 290. In other examples, the QRS onset 282 can be determined by identifying the latest sample point of the QRS waveform 280 that occurred before the peak 288 and had an absolute value equal to or less than a predetermined threshold 292. For example, the threshold 292 may be set to 110% (or other selected percentage) of the minimum absolute value sampling point of the QRS waveform 280 that precedes the peak 288 but is detected within the window 290. Window 290 may be defined as a predetermined time interval extending from a delivered pacing pulse or a sensed cardiac event (e.g., a sensed P-wave or a previously sensed R-wave). Alternatively, window 290 may be defined relative to peak 288 or relative to a QRS sensing threshold crossing.

In other examples, QRS onset 282 may be identified by generating a dispersed waveform from a plurality of QRS waveforms and detecting the onset of the dispersed waveform, as generally disclosed in pre-granted U.S. patent application publication 2018/0263522(Ghosh et al). For example, a dispersion signal may be generated from a plurality of QRS waveforms as a signal representing the electrical dispersion of the QRS waveforms over time. In one example, the dispersive signal is generated by determining a standard deviation of sampling points of a plurality of QRS waveforms. The start of the dispersion signal may be determined as the start of the QRS waveform.

The time of the maximum slope 283 relative to the identified QRS onset 282 can be stored as the electrical activation time of the heart location corresponding to the electrode location of the electrode device 210 from which the QRS waveform 280 was received. Although a single QRS waveform is shown in fig. 7, the electrical activation time for a given electrode "channel" during his bundle pacing may be determined from multiple QRS waveforms received from a given electrode or from a time averaged, filtered or dispersed waveform generated from multiple QRS waveforms as a representative QRS waveform of the cardiac electrical signal corresponding to the location or region of the patient's heart.

Figure 7 depicts a method for determining the electrical activation time from at least one QRS waveform for a given electrode signal. The electrical activation time may be determined using alternating starting, starting or reference time points and subsequent electrical activation time points, defined as fiducial points of the QRS waveform during the QRS window, and indicative of the electrical depolarization time of the corresponding region of the heart. For example, the electrical activation time may be determined as a time from the start 282 to the R-wave peak 288, to a predetermined percentage of the R-wave peak 288, or the like.

Returning to fig. 6, at block 254, the his beam pacing device delivers his beam pacing according to the programmed pacing output control parameters. At block 254, the computing device 240 generates electrical dyssynchrony data during delivery of the his bundle pacing. At block 256, the computing device 240 identifies when a valid his bundle capture occurred based on the electrical dyssynchrony data. In some examples, computing device 240 may compare one or more electrical dyssynchrony metrics to a threshold value that indicates acceptable electrical activation synchrony or homogeneity. For example, if SDAT is less than 25 milliseconds, a valid his bundle capture may be detected. Additionally or alternatively, criteria for detecting a valid his bundle acquisition may include a RVAT of less than 30 milliseconds, a LVAT of less than 30 milliseconds, and/or a MTAT of less than 50 milliseconds, as examples.

In some examples, the computing device 240 may identify or detect a valid his bundle capture in response to detecting a relative change in an electrical dyssynchrony metric (e.g., one or more of SDAT, LVAT, RVAT, and MTAT) determined during his bundle pacing as compared to a similar metric determined as a baseline metric, e.g., when his bundle pacing is not delivered (during patient intrinsic rhythm or during RV pacing). The threshold reduction in the electrical dyssynchrony metric that results in effective bundle capture detection may be 10%, 20%, 25%, 30%, or other predetermined percentage or threshold change. In yet other examples, the his beam pacing may be delivered by the his beam pacing apparatus at multiple pacing pulse outputs (e.g., at multiple pacing pulse voltage amplitudes) as electrical dyssynchrony data is being generated by the computing device 240. At block 256, the computing device 240 may detect an effective his bundle capture based on one or more electrical dyssynchrony metrics reaching a threshold or a maximum reduction from a maximum value of the metrics determined as the his bundle pacing output changes. Thus, effective his bundle capture can be detected based on the relative decrease in SDAT, LVAT, RVAT, and/or MTAT as his bundle pacing pulse energy increases or decreases (or randomly varies).

In some examples, computing device 240 may be configured to identify different types of captures associated with his bundle pacing at block 256. For example, in some patients, incomplete capture of the his bundle may result in capture of either the Right Bundle Branch (RBB) or the Left Bundle Branch (LBB), but not both. Computing device 240 may generate electrical dyssynchrony data by: a right ventricular measure of electrical activation time, e.g., RVAT, is determined from the QRS waveform received from the electrode device 210 corresponding to the electrical cardiac signal received along the right side of the patient, and a left ventricular measure of electrical activation time, e.g., LVAT, is determined from the QRS waveform received from the electrode device 210 corresponding to the electrical cardiac signal received along the left side of the patient. The computing device 240 may compare the right and left ventricular metrics to respective right and left bundle branch capture thresholds to identify an invalid bundle capture. For example, responsive to at least one of the right ventricular metric or the left ventricular metric not satisfying the respective right bundle branch capture threshold or left bundle branch capture threshold, an invalid bundle capture may be identified. To illustrate, if RVAT is less than 30 milliseconds (or other selected threshold) but LVAT is greater than 30 milliseconds (or other selected threshold), then capture of RBBs and capture of LBBs are identified as missing, resulting in identification of an invalid his bundle capture. The his bundle pacing device may respond to the invalid his bundle capture notification by increasing the pacing pulse output, which may cause the valid his bundle capture to be conducted along both the LBB and the RBB.

In some cases, when the his bundle capture threshold is greater than the ventricular myocardium capture threshold, the his bundle pacing pulse may capture ventricular myocardium tissue (VM capture) without capturing the his bundle. Effective capturing of the his bundle with a higher pacing pulse output results in effective his bundle capture, which may include capture of the surrounding ventricular myocardium, i.e., non-selective his bundle capture. The computing device 240 may be configured to distinguish between valid and invalid his bundle captures (which may include only partial activation of the conduction system or only VM capture or complete loss of capture) based on electrical dyssynchrony data. In some cases, a relatively low his bundle pacing pulse that captures the ventricular myocardium without capturing the his bundle may be delivered to establish baseline electrical dyssynchrony data during his bundle uncapture. The computing device 240 may generate electrical dyssynchrony data as the his beam pacing pulse output increases until effective his beam capture is achieved, such that the computing device 240 may identify effective his beam capture based on a comparison with the electrical dyssynchrony data generated during VM capture. In other examples, as the pacing pulse output decreases from the initial high level, the computing device 240 may distinguish between an active his bundle capture and an inactive his bundle capture until a partial capture of the his bundle or just a VM capture is identified, and then decrease further until a complete loss of capture is identified.

When computing device 240 determines that electrical dyssynchrony measures are to be used in block 256 based on a comparison analysis of one or more electrical dyssynchrony measures against a predefined threshold or relative change in one or more measuresWhen the asynchrony data meets the valid his bundle capture criteria, the computing device may generate an indication of his bundle capture at block 258. The indication of his bundle capture may include a notification generated on the display 230 or GUI of the computing device 240 that generates an audible signal, transmits a wireless or wired signal to the external device 50 (fig. 1) for transmission to the his bundle pacing device or transmits a wireless signal directly to the his bundle pacing device, as examples. When generating an indication of his bundle capture as a notification on the display 230 or GUI of the computing device 240, the user may select, via a wireless communication signal (e.g.,signal) to transmit the notification to the his bundle pacing device directly from the computing apparatus 240, or by entering a command in another external device 50 (fig. 1) to transmit the notification to the his bundle pacing device. In other examples, when the computing apparatus 240 effectively detects his bundle capture, the computing apparatus 240 transmits a his bundle capture notification to the his bundle pacing device without user intervention.

In some examples, the pacing output control parameters may be changed by the his beam pacing device during his beam pacing. For example, a predetermined number of pacing pulses may be delivered at each of a plurality of pacing pulse voltage amplitudes, e.g., 5 to 20 or more pulses may be delivered at each of two or more pacing pulse voltage amplitudes delivered at 0.25V, 0.5V, 1.0V, or other selected voltage increments or decrements. The computing device 240 may detect a valid his bundle capture at block 256 based on electrical dyssynchrony data generated during his bundle pacing at different pacing pulse voltage amplitudes (and/or pulse widths). The computing device 240 generates an indication of capture at block 258 in response to identifying a valid his bundle capture. In some examples, the computing device 240 may identify when a missing or invalid his bundle capture is identified and generate an indication of the invalid his bundle capture at block 258. In this manner, the his bundle pacing device may receive notification or confirmation of both a valid his bundle capture and an invalid his bundle capture.

When the computing device 240 is configured to distinguish between different types of his bundle captures, e.g., an invalid his bundle capture causes an RBB or LBB capture but not both or an NSHB to SHB capture, the computing device 240 may generate different notifications to indicate the type of capture detected. In this manner, when generating an invalid his bundle capture notification, the his bundle pacing device may respond to the notification by incrementing the pacing output in an attempt to fully capture the his bundle and wait for confirmation from the computing device 240 that a valid his bundle capture was identified. In some examples, computing device 240 may generate a notification when a NSHB capture is identified and a SHB capture is identified as a his bundle pacing output change.

By generating an indication of his bundle capture at block 258, the computing apparatus 240 provides a notification that may be transmitted to the his bundle pacing device, either directly or indirectly via another device, for use by the his bundle pacing device in establishing a his bundle capture detection threshold. Thus, the his bundle pacing apparatus is able to establish a his bundle capture detection threshold by determining cardiac electrical signal characteristics in response to receiving the notification generated by the computing device 240, while confirming by the computing device 240 that a valid his bundle capture is occurring. Cardiac electrical signal characteristics during a bundle capture inactivity period, including bundle capture loss, may also be determined by the bundle pacing device to facilitate the bundle pacing device in selecting a bundle capture detection threshold that reliably distinguishes between active bundle capture and inactive capture types that may occur during bundle pacing. The his bundle capture threshold may be established by the control circuitry 80 (fig. 3) of the his bundle pacing device that distinguishes between different types of valid his bundle captures (e.g., SHB and NSHB captures) and different types of invalid his bundle captures (e.g., VM, RBB, or LBB only captures). In some examples, the his bundle pacing device control circuit 80 establishes a QRS feature threshold that distinguishes between SHB and NSHB capture. In some cases SHB capture may be required, while in other cases NSHB capture may be desired, which may depend at least in part on which has a higher capture threshold (and thus higher power requirements for generating pacing pulses). Thus, the computing device 240 may be configured to distinguish SHB and NSHB captures and generate a notification of the type of valid his bundle capture detected. The his bundle pacing device has an improved ability to tailor his bundle capture detection threshold for a given patient and a particular type of desired effective his bundle capture (e.g., SHB or NSHB capture).

Fig. 8 is a flowchart 300 of a method for establishing a capture detection threshold performed by system 200 in conjunction with a his bundle pacing device, according to one example. At block 302, control circuitry 80 of a his bundle pacing device (e.g., IMD14 or pacemaker 100) may determine a baseline QRS feature from the cardiac electrical signal received from sensing circuitry 86. One or more baseline QRS features may be determined from near-field signals received from near-field sensing channels 87, far-field signals received from far-field sensing channels 89, or both. The near field and far field signals are generated by a his beam pacing device sensing circuit, such as sensing circuit 86 described above in connection with fig. 3. Examples of near-field and far-field signals that may be generated by the cardiac electrical signal sensing circuitry of the his bundle pacing device are described below in connection with fig. 9.

The baseline QRS waveform characteristic determined by the his bundle pacing device at block 302 may include a QRS width and/or a QRS area determined from the near field and/or far field signals received from the sensing circuitry 86. In other examples, the QRS waveform features determined at block 302 may include a QRS polarity, a QRS time delay, and/or a QRS waveform template representing the overall shape or morphology of the QRS waveform within a particular time window. At block 302, a combination of two or more features may be determined from the near-field signal, the far-field signal, or both the near-field and far-field signals for establishing a baseline QRS waveform feature representative of the uncaptured his bundle. In some examples, the baseline QRS waveform characteristic may be determined by control circuitry 80 when his bundle pacing is inhibited by control circuitry 80 or during RV only pacing delivered by therapy delivery circuitry 84.

At block 304, the his bundle pacing device delivers his bundle pacing. The control circuit 80 may control the therapy delivery circuit 84 to deliver the his bundle pacing pulses according to programmed, default, or most recently used pacing output control parameters. In some examples, the his bundle pacing pulse is delivered at a predetermined starting pulse output (e.g., pulse voltage amplitude for a given pacing pulse width) that is expected to capture the his bundle. In other examples, the pacing pulse output may be set to an initial low value, such as a low pacing pulse voltage amplitude that is not expected to capture the his bundle, or an initial high value, such as a high pacing pulse voltage amplitude that is expected to capture the his bundle.

At block 306, the his bundle pacing device waits for a his bundle capture notification while generating and delivering his bundle pacing pulses. The telemetry circuitry 88 may receive a wireless communication signal directly from the computing device 240 or from another external apparatus 40 indicating that the computing device 240 has identified (detected) a valid his bundle capture based on the analysis of the electrical dyssynchrony metric(s). If the his beam capture notification is not received within an expected time period (e.g., 30 seconds, one minute, two minutes, or other selected time period), or if an invalid his beam capture notification is received at block 306, the control circuitry 80 may adjust the pacing pulse output at block 308. In some examples, the pacing pulse voltage amplitude is increased. In other examples, the pacing pulse width is increased. In yet other examples, when additional his bundle pacing electrode vectors are available, at least one electrode selected for delivering the his bundle pacing pulse may be changed, for example, by switching circuitry included in therapy delivery circuitry 84.

At block 304, the his bundle pacing is delivered by the therapy delivery circuit 84 at the adjusted pacing output setting, and at block 306, the control circuit 80 waits for a his bundle capture notification. The process of adjusting the pacing output control parameters, delivering the his beam pacing using the adjusted control parameters, and waiting for a his beam capture notification by the his beam pacing device may be repeated multiple times until a valid his beam capture is confirmed by the computing device 240, and a notification is generated and received by the his beam pacing device at block 308.

Upon receipt of the his bundle capture notification, the control circuitry 80 determines one or more characteristics of the cardiac electrical signal during confirmed valid his bundle pacing at the pacing output control parameters associated with receipt of the his bundle capture notification. For example, QRS width, QRS area, QRS time delay with the immediately preceding his bundle pacing pulse, QRS polarity, QRS waveform template, and/or other QRS features may be determined at block 310. In some examples, the control circuit 80 compares the determined features to baseline features at block 312 to verify that there is a detectable change or difference between the QRS feature determined during the his bundle capture and the same QRS feature determined during the non-his bundle capture. If the QRS feature is determined to be substantially unchanged (e.g., within a threshold difference or percentage such as 10% or less), then a different QRS waveform feature may be determined at block 310 for monitoring effective his bundle capture.

At block 314, the control circuit 80 sets the his bundle acquisition detection threshold using the QRS waveform features determined during active his bundle acquisition. For example, if QRS width is determined by the control circuitry 80 at block 310, the control circuitry 80 of the his bundle pacing apparatus may set the capture detection threshold to the determined QRS width associated with the his bundle capture detection plus a small offset, e.g., a fixed offset of 5%, 10%, or 20%, or 5 milliseconds of QRS width or other predetermined value, to allow for some variation in QRS width that may occur during effective his bundle capture. When the baseline QRS feature value is determined during his bundle non-capture, the capture detection threshold established at block 314 may be set to a value between the value determined at block 310 and the baseline value determined at block 302, e.g., at the midpoint between the values or at different portions of the difference.

When the computing device 240 is configured to generate notifications corresponding to different types of valid his bundle captures (e.g., SHB and NSHB captures), the his bundle pacing apparatus may determine the QRS feature(s) corresponding to the notification of each of the his bundle capture types and establish a threshold at block 314 for detecting and differentiating the his bundle capture types. Criteria for detecting different types of valid (e.g., SHB and NSHB capture) and invalid his bundle capture (e.g., RBB capture, LBB capture, VM-only capture) may be established by the control circuit 80 at block 314, with each unique set of criteria relating to one or more capture detection thresholds established for a respective one or more QRS features determined from sensed near-field and/or far-field cardiac electrical signals of the his bundle pacing device.

Fig. 9 is a graph 400 of cardiac electrical signals that may be produced by a his bundle pacing device. The cardiac electrical signal includes evoked response QRS waveform signals representative of SHB capture (left column), NSHB capture (right column), and VM capture (middle column). In each example, the far-field cardiac electrical signal 402 and the corresponding his-beam near-field signal 412 are shown as being temporally aligned with the respective his-beam pacing pulse 410, 415, or 417.

In the left column, the his bundle pacing pulse 410 that causes SHB capture produces a his bundle near-field evoked response QRS waveform 414 that occurs after a time delay 420. The his bundle near field QRS waveform 414 has a positive polarity and a relatively narrow signal width in some patients during effective his bundle capture. The far-field evoked response QRS waveform 404 is also considered to be relatively narrow, positive in polarity, and occurs after a time delay. The time delay 420 after the effective his bundle pacing pulse 410 until the QRS waveform 414 is due to the time required to depolarize along the his purkinje conduction system.

In the middle column, the far-field evoked response QRS waveform 406 and the corresponding near-field evoked response QRS waveform 416 are shown after an ineffective his bundle pacing pulse 415 that only captures ventricular myocardial tissue and does not capture the his bundle. Since there is no conduction along the hilkurkinje conduction system after the ineffective his bundle pacing pulse 415, the near field QRS waveform 416 appears after a time delay 422 that is relatively shorter than the time delay 420 of the QRS waveform 414 during effective SHB capture. The near field evoked response QRS waveform 416 during VM capture is relatively wide and has negative polarity. The wide QRS waveform width is evidence of increased electrical dyssynchrony during ineffective his bundle capture.

The far-field QRS waveform 408 and the his bundle near-field QRS waveform 418 during NSHB acquisition are shown in the right column. In the his bundle near-field signal 412, the QRS waveform 416 (middle column) during ineffective his bundle acquisition (VM acquisition) and the QRS waveform 418 (right column) during effective his bundle acquisition are substantially similar. Both signals 416 and 418 occur earlier after the respective his bundle pacing pulses 415 and 417, both negative in polarity, and having a QRS waveform width that is relatively wider than the SHB QRS waveform 414. Thus, for example, based on a longer time delay 420 until the QRS waveform 414, a positive polarity (at least in some patients), a relatively narrow QRS wave width, a relatively small QRS waveform area, or any combination thereof, effective his bundle pacing resulting in SHB capture may be actively detected from the his bundle near-field signal 412. The similarity in timing and morphology of the his bundle near-field evoked response signal 418 during active, NSHB capture and the near-field evoked response signal 416 during inactive VM capture may make these two types of capture difficult to distinguish from the his bundle near-field signal in some patients, particularly when the far-field signal 402 is not available in a his bundle pacing device. Thus, when a notification is received from the computer apparatus 240 indicating confirmation of a valid his bundle capture, establishing, by the control circuit 80 of the his bundle pacing device, a his bundle capture detection threshold based on the QRS waveform features may improve performance of the his bundle pacing device in detecting a valid his bundle capture, even if the valid his bundle capture includes capture of nearby ventricular myocardial tissue.

In the example of fig. 9, the far-field evoked QRS waveform 408 during active NSHB capture is narrower than the far-field QRS waveform 406 during inactive VM capture. When the far-field signal 402 is available in the his bundle pacing device, establishing the his bundle capture detection threshold may include establishing a threshold based on a characteristic of the far-field signal (e.g., based on a far-field evoked response signal width, area, and/or QRS waveform morphology). The his bundle capture detection threshold established by the control circuit 80 based on the far-field QRS waveform can increase the reliability of the his bundle pacing device in detecting a valid his bundle capture, and can be used alone or in combination with the capture detection threshold based on the near-field QRS waveform. A threshold for QRS width, a threshold for QRS area, or a waveform template for his bundle capture detection may be established or determined by the his bundle pacing apparatus in conjunction with electrical dyssynchrony data and his bundle capture notifications generated by computing device 240 (of fig. 4). Any of the characteristics of the far-field signal 402 and/or the near-field signal 412 may be determined by the his bundle pacing apparatus in response to receiving a notification that the computing device 240 has detected a valid his bundle capture for establishing a his bundle capture detection threshold to be applied to a given characteristic of his bundle capture monitoring.

Fig. 10 is a flow diagram 500 of a method for monitoring and maintaining effective his bundle capture by a his bundle pacing device using an established his bundle capture detection threshold, according to one example. In some examples, the process of flowchart 500 may be performed as each his bundle pacing pulse is delivered by a his bundle pacing device. Confirming effective bundle capture by each pacing pulse enables the bundle pacing device to track the overall effectiveness of bundle pacing, for example, by determining the percentage of bundle-captured bundle pacing pulses detected among all bundle pacing pulses delivered. In other examples, the process of flow chart 500 may be performed once per day, once per hour, once per minute, or other frequency or predetermined acquisition monitoring schedule. In some examples, the process of flow chart 500 is performed when a triggering event occurs, such as detecting a change in lead impedance or detecting other changes that may be related to or indicative of a change in the his bundle pacing capture threshold.

At block 502, bundle pacing is delivered according to the programmed pacing therapy protocol and bundle pacing control parameters. In some examples, the process of flowchart 500 may be performed as part of a pacing capture threshold test, where the his bundle pacing pulse delivered at block 502 is one of a sequence of delivered variable pacing amplitude pulses (or variable pulse widths) to determine the lowest pulse amplitude (or lowest pulse width) that results in effective his bundle capture.

At block 504, after therapy delivery circuit 84 delivers the his bundle pacing pulse, cardiac electrical signal characteristics, in particular, QRS waveform characteristics, are determined by control circuit 80 from the cardiac electrical signal received from sensing circuit 86 for which control circuit 80 has established a capture detection threshold as described in connection with fig. 8. In some examples, when multiple capture detection thresholds are established, multiple QRS waveform characteristics may be determined by the control circuitry 80. At block 506, the control circuitry 80 compares the determined cardiac electrical signal characteristic(s) to the corresponding previously established capture detection threshold(s). If the comparison(s) based on the determined QRS waveform feature(s) to the established capture detection threshold(s) satisfies the his bundle capture detection criteria, the control circuit 80 detects his bundle capture at block 508.

When the control circuit 80 does not detect a valid his bundle capture at block 508, e.g., based on one or more determined QRS features not satisfying the capture detection threshold, the control circuit 80 may signal the therapy delivery circuit 84 to adjust the pacing pulse output at block 510, e.g., by increasing the pacing pulse amplitude and/or pulse width. The next his bundle pacing pulse may be delivered at block 502 according to the increased pulse output (or other adjustment of his bundle pacing control parameters, such as the pacing electrode vector), and the process of detecting capture using the previously established capture detection threshold is repeated.

When bundle capture monitoring includes maintaining a percentage of valid bundle pacing pulses by the control circuitry 80, the percentage of pacing pulses detected as captured may be updated at block 512 after a determination is made at block 508 that a valid bundle capture (or an invalid bundle capture). The percentage updated by the control circuit 80 at block 512 may be determined as the percentage of all delivered his bundle pacing pulses of the his pacing therapy delivered by the therapy delivery circuit 84 that results in a valid his bundle capture detection either from the initiation of therapy or by the control circuit 80 within a predetermined time interval (e.g., within a 24 hour interval or within a week, as examples). If the process of flowchart 500 is performed by the his bundle pacing device as part of the capture threshold test, the pacing pulse voltage amplitude and/or pulse width corresponding to the valid capture detection (the "yes" branch) or the invalid capture detection (the "no" branch) of block 508 may be stored in memory 82 of block 512 to enable control circuitry 80 to determine the lowest pacing output at which valid his bundle capture was detected based on the his bundle capture threshold.

After updating the data related to his capture monitoring in memory 82 at block 512, the control circuit 80 continues the process of flowchart 500 by returning to block 502 to control the delivery of the next his bundle pacing pulse (by therapy delivery circuit 84), which may control the delivery of parameters at the adjusted his pacing output. In this manner, the his bundle pacing device is configured to maintain or facilitate effective his bundle capture by determining whether effective his bundle capture occurs based on the established his bundle capture detection threshold(s) and adjusting his bundle pacing control parameters in response to not detecting effective his bundle capture in order to restore effective his bundle capture.

Some techniques of the present disclosure are described by the following illustrative embodiments.

Embodiment 1. a medical device system, comprising:

an electrode device comprising a plurality of external electrodes configured to monitor a plurality of body surface electrical signals of a patient; and

a computing device containing processing circuitry and coupled to the electrode device and configured to:

generating cardiac electrical dyssynchrony data from body surface electrical signals received from a plurality of external electrodes during delivery of the bundle of his pacing pulses;

identifying an effective his bundle capture by his bundle pacing pulses based on the electrical dyssynchrony data, wherein the effective his bundle capture includes capture of both a left bundle branch and a right bundle branch of the his bundle; and

an indication of his bundle acquisition is generated in response to identifying a valid his bundle acquisition.

Embodiment 2. the system of embodiment 1, further comprising a his bundle pacing device comprising:

sensing circuitry configured to sense cardiac electrical signals;

a therapy delivery circuit configured to deliver a bundle of his pacing pulses; and

a control circuit coupled to the sensing circuit and the therapy delivery circuit and configured to:

receiving a communication signal corresponding to an indication of his bundle capture generated by a computing device;

determining a characteristic of the cardiac electrical signal in response to receiving the communication signal; and

a capture detection threshold is established based on the determined characteristic of the cardiac electrical signal.

Embodiment 3. the system of embodiment 2, wherein the control circuitry is further configured to control the therapy delivery circuitry to maintain effective his bundle capture by:

determining a characteristic of a cardiac electrical signal received from the sensing circuit after a his bundle pacing pulse delivered by the therapy delivery circuit;

comparing the feature to an established capture detection threshold; and

the pacing control parameters used by the therapy delivery circuit are adjusted to deliver the his bundle pacing pulses in response to the feature not satisfying the established capture detection threshold.

Embodiment 4. the system of any of embodiments 2 to 3, wherein the computing device is configured to generate the notification by transmitting a wireless signal,

the his bundle pacing apparatus includes a telemetry circuit configured to receive a wireless signal directly from a computing device.

Embodiment 5. the system of any of embodiments 2 to 4, wherein the control circuitry is configured to determine the characteristic of the cardiac electrical signal by determining at least one of:

QRS width, QRS area, QRS polarity, QRS morphology and QRS time delay from the his bundle pacing pulse.

Embodiment 6. the system of any of embodiments 1 to 5, wherein the computing device is further configured to:

generating baseline electrical dyssynchrony data in the absence of a his bundle pacing pulse; and

bundle capture is identified by comparing electrical dyssynchrony data generated during delivery of bundle of his pacing pulses to baseline electrical dyssynchrony data.

Embodiment 7. the system of embodiment 6, wherein the baseline electrical dyssynchrony data is generated during delivery of pacing pulses that capture the ventricular myocardium without capturing the his bundle.

Embodiment 8 the system of any of embodiments 1 to 7, wherein the computing device is configured to:

generating electrical asynchrony data by:

determining an electrical activation time from a plurality of QRS waveforms received from the electrode device, an

Determining a measure of electrical activation time; and

effective his beam capture is identified by comparing a measure of electrical activation time to a threshold.

Embodiment 9. the system of any of embodiments 1 to 8, wherein the computing device is further configured to:

generating electrical asynchrony data by:

determining a right ventricular measure of electrical activation time from a first plurality of QRS waveforms received from the electrode device corresponding to body surface electrical signals received along the right side of the patient, an

Determining a left ventricular measure of electrical activation time from a second plurality of QRS waveforms of body surface electrical signals received from external electrodes of the electrode device along the left side of the patient; and

identifying a valid bundle of his capture by:

comparing the right and left ventricular metrics to respective right and left bundle branch capture thresholds; and

identifying a valid bundle capture in response to both the right ventricular metric and the left ventricular metric satisfying respective right bundle branch capture thresholds and left bundle branch capture thresholds.

Embodiment 10 the system of any of embodiments 1-9, wherein the computer device is further configured to:

distinguishing at least two different types of his bundle captures from a selective his bundle capture, a non-selective his bundle capture, a ventricular-only myocardium capture, a right bundle branch capture, and a left bundle branch capture based on an analysis of the generated electrical dyssynchrony data; and

a notification corresponding to the differentiated type of his bundle acquisition is generated.

Embodiment 11 the system of any of embodiments 1-10, wherein the electrode device comprises an electrode array coupled to a substrate configured to encircle a torso of the patient.

Embodiment 12. a method performed by a medical device system, comprising:

receiving, by a computing device, a body surface electrical signal from an electrode device comprising a plurality of external electrodes;

generating, by a computing device, electrical dyssynchrony data from body surface electrical signals received from a plurality of external electrodes during delivery of the bundle of his pacing pulses;

identifying, by the computing device, a valid his bundle capture based on the electrical asynchrony data, wherein the valid his bundle capture includes capture of both a left bundle branch and a right bundle branch of the his bundle; and

an indication of the his bundle acquisition is generated by the computing device in response to identifying the valid his bundle acquisition.

Embodiment 13. the method according to embodiment 12, further comprising:

delivering, by therapy delivery circuitry of the bundle of his pacing device, a bundle of his pacing pulses;

sensing, by a sensing circuit of the his bundle pacing device, a cardiac electrical signal;

receiving, by a telemetry circuit of the his bundle pacing apparatus, a communication signal corresponding to an indication of his bundle capture generated by a computing device;

determining, by control circuitry of the his bundle pacing device, a characteristic of the sensed cardiac electrical signal in response to receiving the communication signal; and

a capture detection threshold is established based on the determined characteristics of the sensed cardiac electrical signal.

Example 14. the method according to example 13, further comprising maintaining his bundle capture by:

determining a characteristic of a cardiac electrical signal received from the sensing circuit after a his bundle pacing pulse delivered by the therapy delivery circuit;

comparing the feature to an established capture detection threshold; and

the pacing control parameters used by the therapy delivery circuit are adjusted to deliver the his bundle pacing pulses in response to the feature not satisfying the established capture detection threshold.

Embodiment 15. the method according to any one of embodiments 13 to 14, further comprising:

generating a notification by transmitting a wireless signal by a computing device; and

the wireless signal is received by the his bundle pacing apparatus directly from the computing device.

Embodiment 16. the method of any of embodiments 13-15, wherein determining a characteristic of the cardiac electrical signal comprises determining at least one of:

QRS width, QRS area, QRS polarity, QRS morphology and QRS time delay from the his bundle pacing pulse.

Embodiment 17. the method of any one of embodiments 12 to 16, further comprising:

generating, by a computing device, baseline electrical dyssynchrony data in the absence of a his bundle pacing pulse; and

bundle capture is identified by comparing electrical dyssynchrony data generated during delivery of bundle of his pacing pulses to baseline electrical dyssynchrony data.

Embodiment 18. the method of embodiment 17, further comprising generating baseline electrical dyssynchrony data during delivery of the pacing pulses that capture the ventricular myocardium without capturing the his bundle.

Embodiment 19. the method of any of embodiments 12 to 18, further comprising:

generating electrical dyssynchrony data comprises:

determining an electrical activation time from a plurality of QRS waveforms received from the electrode device, an

Determining a measure of electrical activation time; and

identifying a valid his beam capture involves comparing a measure of electrical activation time to a threshold.

Embodiment 20. the method of any one of embodiments 12 to 19, further comprising:

generating electrical dyssynchrony data comprises:

determining a right ventricular measure of electrical activation time from a first plurality of QRS waveforms received from the electrode device corresponding to body surface electrical signals received along the right side of the patient, an

Determining a left ventricular measure of electrical activation time from a second plurality of QRS waveforms of body surface electrical signals received from external electrodes of the electrode device along the left side of the patient; and

identifying a valid his bundle capture comprises:

comparing the right and left ventricular metrics to respective right and left bundle branch capture thresholds; and

identifying a valid bundle capture in response to both the right ventricular metric and the left ventricular metric satisfying respective right bundle branch capture thresholds and left bundle branch capture thresholds.

Embodiment 21. the method according to any of embodiments 12 to 20, further comprising:

distinguishing at least two different types of his bundle captures from a selective his bundle capture, a non-selective his bundle capture, a ventricular-only myocardium capture, a right bundle branch capture, and a left bundle branch capture based on an analysis of the generated electrical dyssynchrony data; and

a notification corresponding to the differentiated type of his bundle acquisition is generated.

Embodiment 22 the method of any of embodiments 12-21, wherein receiving body surface electrical signals from the electrode device includes receiving body surface electrical signals from an array of a plurality of external electrodes coupled to a substrate configured to surround a torso of the patient.

Example 23 a non-transitory computer readable storage medium containing a set of instructions that, when executed by a processor of a computing apparatus of a medical device system, cause the computing apparatus to:

receiving a body surface electrical signal from an electrode device comprising a plurality of external electrodes;

generating electrical dyssynchrony data from body surface electrical signals received from a plurality of external electrodes during delivery of the bundle of his pacing pulses;

identifying an effective his bundle capture based on the electrical asynchrony data, wherein the effective his bundle capture includes capture of both a left bundle branch and a right bundle branch of the his bundle; and

an indication of his bundle acquisition is generated in response to identifying a valid his bundle acquisition.

It will be understood that, depending on the example, certain acts or events of any of the methods described herein can be performed in a different order, may be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the methods). Further, in some examples, acts or events may be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors, rather than sequentially. Additionally, although certain aspects of the disclosure are described as being performed by a single circuit or unit for purposes of clarity, it should be understood that the techniques of this disclosure may be performed by a combination of circuits or components associated with, for example, a medical device.

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 on a computer-readable medium in the form of one or more instructions or code and may be executed by a hardware-based processing unit. The 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 that can be accessed by a computer).

The 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 circuitry. Thus, as used herein, the term "processor" may refer to any of the foregoing structure or any other structure suitable for implementation of the techniques described herein. Also, the techniques may be implemented entirely in one or more circuits or logic elements.

Accordingly, a medical device system has 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 different combinations than the specific combinations presented in the figures. It should be appreciated that various modifications to the reference examples may be made without departing from the scope of the disclosure and the appended claims.