Medical devices and methods for ventricular sensing control in cardiac pacing systems

Abstract

A medical device is configured to set a post-atrial time interval in response to an atrial event and to generate an event time signal in response to a ventricular electrical signal exceeding an R-wave sensing threshold during the post-atrial time interval. In some instances, the device accumulates oversensing evidence in response to the event time signal and adjusts ventricular sensing control parameters based on the accumulated oversensing evidence.

Description

Technical Field

[0001] This disclosure relates to a medical device and method for controlling the sensing of ventricular events based on evidence of oversensing. Background Technology

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

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

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

[0005] Ventricular pacing via electrodes located at or near the apex of the right ventricle has been found to be associated with an increased risk of atrial fibrillation and heart failure. Alternative pacing sites, such as His bundle pacing, have been investigated or proposed. His bundle cardiac pacing has been proposed to provide ventricular pacing along the heart's natural conduction system. Ventricular pacing via the His bundle allows recruitment along the heart's natural conduction system, including Purkinje fibers, and is hypothesized to promote more physiological activation of the normal heart than other pacing sites such as the ventricular apex. Summary of the Invention

[0006] The technology disclosed herein generally relates to controlling ventricular sensing in a medical device capable of pacing the heart. In some instances, the medical device is capable of delivering ventricular pacing pulses, which may be delivered to the His bundle or along the His-Purkinje system. A medical device operating according to the technology disclosed herein detects evidence of oversensing through a ventricular channel of the medical device and adjusts ventricular sensing control parameters based on the evidence of oversensing. Evidence of oversensing may involve oversensing of atrial events and / or oversensing of cardiac potential signals. Adjustable ventricular sensing control parameters include the post-atrial ventricular blanking period, the post-atrial safe pacing interval, and / or a ventricular sensitivity setting used to control the R-wave sensing threshold for sensing ventricular R waves.

[0007] In one example, this disclosure provides a medical device including a sensing circuit configured to sense a ventricular electrical signal, set an R-wave sensing threshold, set a post-atrial time interval in response to receiving an atrial event signal, and generate an event time signal in response to the ventricular electrical signal being equal to or greater than the R-wave sensing threshold during the post-atrial time interval. The medical device further includes a control circuit configured to determine a count of the event time signal generated by the sensing circuit and adjust ventricular sensing control parameters based on the count of the event time signal.

[0008] In another example, this disclosure provides a method comprising sensing a ventricular electrical signal, setting an R-wave sensing threshold, receiving an atrial event signal, setting a post-atrial time interval in response to receiving the atrial event signal, and generating an event time signal in response to the ventricular electrical signal being equal to or greater than the R-wave sensing threshold during the post-atrial time interval. The method includes determining a count of the event time signal and adjusting ventricular sensing control parameters based on the count of the event time signal.

[0009] In another example, this disclosure provides a non-transitory computer-readable storage medium storing a set of instructions that, when executed by the control circuitry of a medical device, cause the medical device to sense a ventricular electrical signal, set an R-wave sensing threshold, receive an atrial event signal, set an after-atrial time interval in response to receiving the atrial event signal, generate an event time signal in response to the atrial electrical signal being equal to or greater than the R-wave sensing threshold during the after-atrial time interval, determine a count of the event time signal, and adjust ventricular sensing control parameters based on the count of the event time signal.

[0010] Details of one or more aspects of this disclosure are set forth in the accompanying drawings and the following description. Other features, objectives, and advantages of the technology described in this disclosure will be apparent from the specification, drawings, and claims. Attached Figure Description

[0011] Figure 1 This is a conceptual diagram of an implantable medical device (IMD) system that enables a patient's heart to be paced and senses electrical signals from the heart.

[0012] Figure 2 yes Figure 1 A conceptual diagram of the IMD, which connects to the ventricular lead that advances to the alternative ventricular sensing and pacing location.

[0013] Figure 3 This is a conceptual diagram of a leadless intracardiac pacemaker positioned within the right atrium to provide ventricular pacing via the His bundle.

[0014] Figure 4 This is a schematic diagram of a circuit system that can be enclosed within an IMD, which is configured to perform sensing and pacing using the techniques disclosed herein.

[0015] Figure 5 It can be included in Figure 4 A schematic diagram of the circuitry in the ventricular channel of the sensing circuit shown.

[0016] Figure 6 This means that it can be done by Figure 5 Timing diagram of signals generated by the ventricular pathway.

[0017] Figure 7 This is a flowchart of a method that can be performed by a medical device for accumulating evidence of oversensing and adjusting ventricular sensing control parameters.

[0018] Figure 8 This is a flowchart of a method for accumulating evidence of oversensing and adjusting ventricular sensing control parameters based on the accumulated evidence of oversensing, according to another example.

[0019] Figure 9 This is a flowchart of a method for controlling ventricular sensing control parameters based on evidence of oversensing in the presence of atrial tachyarrhythmia (AT), according to an example. Detailed Implementation

[0020] This article describes a medical device system capable of generating and delivering ventricular pacing pulses and sensing cardiac electrical signals. When ventricular electrodes are positioned to sense ventricular signals and deliver pacing pulses to or near the His bundle, the ventricular electrodes may also be relatively close to the atrial ventricle. Therefore, the cardiac electrical signals received by the ventricular sensing electrodes may include P waves accompanied by inherent atrial depolarization, atrial pacing pulse artifacts, and atrial evoked response signals following the atrial pacing pulse. Any of these atrial events present in the ventricular sensing signal may be erroneously sensed as R waves by the medical device. This erroneous sensing of atrial events as R waves is referred to herein as “atrial event oversensing.”

[0021] In some cases, His bundle potentials or bundle branch potentials (referred to herein as “cardiac potentials”) that may precede the QRS waveform may be present in the ventricular sensing signal, particularly when the sensing electrodes are located near the His bundle or bundle branches. For example, the H wave may be erroneously oversensed as an R wave when the amplitude of the His bundle potential (also referred to herein as the “H wave”) exceeds the R wave sensing threshold. Therefore, the term “oversensing” as used herein can refer to the oversensing of atrial events and / or underlying cardiac signals generated by the His-Purkinje system prior to ventricular myocardial depolarization. For example, an H wave can occur between a real atrial event and a real R wave. An H wave following an atrial event may or may not follow the intrinsically conducted R wave, depending on the presence of a conduction block along the His-Purkinje system. Thus, in some cases, oversensing of H waves or other cardiac potentials generated by the His-Purkinje system may lead to the maintenance of ventricular pacing pulses, which could result in ventricular pauses or ventricular rhythm arrest in the presence of a conduction block.

[0022] This document discloses techniques for accumulating evidence of oversensing, which may or may not include actual oversensing that leads to the sensing of erroneous R waves and thus generates erroneous R-wave sensing event signals. As described below, accumulating evidence of oversensing may include determining a count of oversensing events. Oversensing events may be identified based on ventricular electrical signals that cross an R-wave sensing threshold during a post-atrial time interval. In response to an R-wave sensing threshold crossover identified as an oversensing event, an R-wave sensing event signal may or may not be generated. Depending on whether the sensing threshold crossover occurs during a post-atrial blanking interval, an R-wave sensing event signal may or may not be generated. Therefore, an oversensing event may or may not be an actual oversensing event.

[0023] The medical device disclosed herein controls ventricular sensing control parameters based on evidence of oversensing to avoid or reduce the likelihood of erroneously sensing atrial events and / or cardiac potential signals as R waves. Such oversensing can cause the medical device to maintain ventricular pacing pulses, which may lead to ventricular arrhythmia or ventricular rhythm arrest, potentially reducing the benefits and effectiveness of pacing therapy or even causing patient symptoms. By using the techniques disclosed herein to control ventricular sensing control parameters based on evidence of oversensing, overall medical device performance is improved. The reliability and specificity of ventricular R-wave sensing are improved, and the effectiveness of subsequently delivered pacing therapy is enhanced because the suppression or delivery of ventricular pacing pulses is based on more reliable R-wave sensing.

[0024] Figure 1 This is a conceptual diagram of a medical device system 10 capable of pacing a patient's heart 8 and sensing cardiac electrical signals. System 10 includes an implantable medical device (IMD) 14 connected to the patient's heart 8 via transvenous medical leads 16 and 18. The IMD 14 is shown as a dual-chamber device capable of delivering cardiac pacing pulses and sensing cardiac electrical signals in the atrial and ventricular chambers. The IMD housing 15 is closed and coupled below. Figure 4 The various circuits and components described correspond to an internal circuitry system for sensing cardiac signals from the heart 8 and controlling electrical stimulation therapy, such as pacing therapy, delivered by the IMD 14. Specifically, the circuitry enclosed by the housing 15 controls ventricular sensing by adjusting one or more ventricular sensing control parameters in response to evidence of actual or potentially oversensitized atrial events and / or potential cardiac signals detected in the His bundle or bundle branches.

[0025] The IMD 14 includes a connector block 12, which can be configured to receive the proximal ends of an atrial pacing and sensing lead 16 (hereinafter referred to as "atrial lead" 16) and a ventricular pacing and sensing lead 18 (hereinafter referred to as "ventricular lead" 18). Each of the leads 16 and 18 is advanced via a vein to position electrodes for sensing and stimulation in the atrium and ventricle, respectively. The atrial lead 16 can be positioned such that its distal end is located near the right atrium (RA) and the superior vena cava. The atrial lead 16 is equipped with pacing and sensing electrodes, shown as a tip electrode 20 and a ring electrode 22 spaced proximally from the tip electrode 20. Electrodes 20 and 22 provide sensing and pacing in the right atrium and are each connected to a corresponding insulated conductor extending within the elongated body of the atrial lead 16. Each insulated conductor is coupled at its proximal end to a connector carried by a proximal lead connector 40 and thereby electrically coupled to the internal IMD circuitry via the connector block 12.

[0026] As shown in the figure, the ventricular lead 18 can advance within the right atrium to position electrodes 32 and 34 for pacing and sensing near the His bundle according to the right atrial method. The tip electrode 32 of the ventricular lead can be a helical electrode that can advance to the lower end 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. A ring electrode 34, spaced proximally from the tip electrode 32, can serve as a return electrode with the cathode tip electrode 32 for pacing the right and left ventricles via the His-Purkinje system. Although lead 18 is referred to herein as a ventricular pacing and sensing lead for delivering pacing pulses for pacing the ventricles, it can be referred to as a His bundle pacing and sensing lead when positioned for delivering pacing pulses to the ventricles via the His-Purkinje system. It should be understood that... Figure 1 The positions of lead 18 and electrodes 32 and 34 shown are illustrative in nature, and lead 18 and electrodes 32 and 34 can be positioned to deliver pacing pulses to the His bundle, right and / or left bundle branches, Purkinje fibers, or any location along the heart's natural conduction system to facilitate depolarization of the right and left ventricles via the heart's natural conduction system. In other instances, ventricular lead 18 and electrodes 32 and 34 can be positioned to deliver ventricular pacing pulses to the ventricular myocardium, for example, along the interventricular septum or the free wall of the ventricle. Therefore, electrodes 32 and 34 are not limited to pacing and sensing at or near the His bundle as shown, but can be used to deliver ventricular pacing and sense ventricular R waves at other locations along the His-Purkinje system or along the ventricular myocardium.

[0027] Electrodes 32 and 34 are coupled to corresponding insulated conductors extending within the elongated body of the ventricular lead 18, providing electrical connection to the proximal lead connector 44 coupled to the connector block 12, and thereby achieving electrical connection to the IMD circuitry enclosed by the housing 15. As described below, the cardiac electrical signal sensing circuitry included in the IMD 14 receives cardiac electrical signals from electrodes 32 and / or 34 of the ventricular lead 18 to sense ventricular R waves. Electrodes 32 and 34 can be selected from a bipolar ventricular sensing electrode vector, or a single electrode carried by the ventricular lead 18 (e.g., tip electrode 32 or ring electrode 34) can be used in combination with the housing 15 to receive unipolar ventricular signals for sensing R waves by the cardiac electrical signal sensing circuitry. Although the atrial lead 16 and the ventricular lead 18 are each shown carrying two electrodes, it is understood that each lead may carry one or more electrodes for providing one or more selectable pacing and / or sensing electrode vectors, said one or more electrodes may include a bipolar combination of electrodes carried by the respective lead or a unipolar combination of electrodes carried by the respective lead and the IMD housing 15.

[0028] The IMD 14 can be configured as a dual-chamber pacemaker capable of sensing and pacing in the RA and sensing ventricular R waves and delivering ventricular pacing pulses synchronized with the atria in an atrial-tracking ventricular pacing mode. In other instances, the IMD 14 can be coupled to a single lead advancing into the RA for sensing atrial and ventricular signals and at least delivering ventricular pacing pulses. The IMD 14 can also be a single-chamber pacing device coupled only to the ventricular lead 18, wherein both atrial and ventricular electrical signals are sensed and pacing pulses are delivered to the ventricles to at least maintain a minimum ventricular rate and / or deliver ventricular pacing synchronized with the atria. It should be understood that, although in Figure 1 The diagram illustrates IMD 14 as a pacemaker capable of delivering atrial and ventricular pacing; however, IMD 14 can be configured as an implantable cardioverter-defibrillator capable of delivering both low-pressure cardiac pacing therapy and high-pressure cardioversion and defibrillation (CV / DF) shocks. In this configuration, IMD 14 can be coupled to at least one lead carrying at least one high-pressure CV / DF electrode (e.g., an elongated coil electrode).

[0029] External device 50 is shown to be in telemetry communication with IMD 14 via communication link 60. External device 50 may include processor 52, memory 53, display unit 54, user interface 56, and telemetry unit 58. Processor 52 controls the operation of external device and processes data and signals received from IMD 14. Display unit 54, which may include a graphical user interface, displays data and other information to the user to view IMD operation and programming parameters, as well as cardiac electrical signals retrieved from IMD 14. Data obtained from IMD 14 via communication link 60 may be displayed on display 54. For example, a clinician may view cardiac electrical signals and labeled channel data received from IMD 14 and / or data derived therefrom. For example, processor 52 may generate a report of oversensitivity evidence accumulated by IMD 14, as well as any associated ventricular sensing control parameter adjustments based on the oversensitivity evidence, for display to the user on display 54.

[0030] User interface 56 may include a mouse, touchscreen, keypad, etc., to enable a user to interact with external device 50 to initiate a telemetry session with IMD 14 for retrieving data from and / or transmitting data to IMD 14, including programmable parameters for detecting evidence of oversensing and controlling ventricular sensing, as described herein. Telemetry unit 58 includes a transceiver and antenna configured for bidirectional communication with telemetry circuitry included in IMD 14 and configured to operate in conjunction with processor 52 to transmit and receive data related to IMD functionality via communication link 60, including data or related data concerning oversensing detection and automatic adjustment of ventricular sensing control parameters.

[0031] Can use such as A communication link 60 is established between IMD 14 and external device 50 via Wi-Fi, Medical Implant Communication Service (MICS), or other RF or communication frequency bandwidth or communication protocol wireless radio frequency (RF) links. Upon querying a command, external device 50 can retrieve data stored or acquired by IMD 14, including physiological signals or associated data derived therefrom, device diagnostic results, detected rhythmic events, and the history of therapy delivery.

[0032] External device 50 may be embodied as a programmer used in a hospital, clinic, or physician's office to retrieve data from IMD 14 and program the operating parameters and algorithms in IMD 14 to control IMD functionality. External device 50 may alternatively be embodied as a home monitor or handheld device. External device 50 may be used to program cardiac signal sensing parameters, heart rate detection parameters, and treatment control parameters used by IMD 14. Thresholds or other parameters for ventricular sensing and oversensing detection according to the techniques disclosed herein may be programmed into IMD 14 using external device 50.

[0033] Figure 2 This is a conceptual diagram of an IMD 14 connected to a ventricular lead 18 that advances to an alternative ventricular sensing and pacing location. The IMD 14 can be a dual-chamber cardiac pacing device connected to both the ventricular lead 18 and the atrial lead 16. In this example, the distal portion of the ventricular lead 18 advances within the RV to sense ventricular electrical signals and deliver ventricular pacing pulses to the His bundle or His-Purkinje system according to a right ventricular approach.

[0034] The tip electrode 32 can be implanted into or along the ventricular septum, for example, high up along the ventricular septum near the His bundle. The tip electrode 32 can be paired with the return anode loop electrode 34 for delivering ventricular pacing pulses to capture the natural ventricular conduction system and / or ventricular myocardium and for sensing ventricular electrical signals, including the intrinsic R wave and ventricular evoked response signals. In some instances, the tip electrode 32 or the loop electrode 34 can be paired with the IMD housing 15 for unipolar sensing of ventricular signals.

[0035] When electrodes 32 and 34 are adjacent to the right atrium, for example, in Figure 1 The method shown in the right atrium or Figure 2In the illustrated right ventricular approach, the ventricular sensing circuitry of IMD 14 may incorrectly sense atrial events as R waves. When electrodes 32 and 34 are near the His bundle, the His bundle potential signal or H wave may be incorrectly sensed as an R wave from the ventricular sensing signal. The technology disclosed herein enables IMD 14 to detect evidence of oversensing and / or evidence indicating the potential for oversensing when it occurs and to take corrective action to reduce the likelihood of oversensing of atrial events and / or H waves (or bundle branch potential) by adjusting the ventricular sensing control parameters.

[0036] Figure 3 This is a conceptual diagram of a leadless intracardiac pacemaker 100 positioned within an RA (radial artery apnea) for delivering ventricular pacing via the His bundle. The pacemaker 100 may include a distal tip electrode 102 extending distally 112 away from the pacemaker housing 105. The intracardiac pacemaker 100 is shown implanted in the RA of a patient's heart 8 to position the distal tip electrode 102 to deliver pacing pulses to the His bundle. For example, the distal tip electrode 102 may be inserted at the lower end of the atrial septum, below the AV node, and near the tricuspid annulus to position the tip electrode 102 along, along, or near the His bundle. The distal tip electrode 102 may be a helical electrode providing fixation to anchor the pacemaker 100 at the implantation site. In other instances, the pacemaker 100 may include a fixation member comprising one or more teeth, hooks, barbs, helices, or other fixation members for anchoring the distal end of the pacemaker 100 at the implantation site.

[0037] A portion of the distal tip electrode 102 may be electrically insulated, such that only the most distal end of the tip electrode 102, furthest from the distal end 112 of the housing, is exposed to provide targeted pacing at a tissue site including a portion of the His bundle. One or more housing-based electrodes 104 and 106 may be carried on the surface of the pacemaker housing 100. Electrodes 104 and 106 are shown as annular electrodes extending from the distal end 112 to the longitudinal sidewall of the proximal end 110 of the pacemaker housing 105. In other instances, a return anode electrode for sensing and pacing may be positioned on the proximal end 110 of the housing. For example, ventricular pacing via the His-Purkinje system can be achieved using the distal tip electrode 102 as the cathode and either of the housing-based electrodes 104 and 106 as the return anode.

[0038] The cardiac electrical signals generated by the heart 8 can be sensed by the pacemaker 100 using sensing electrode pairs selected from electrodes 102, 104, and 106. For example, the distal tip electrode 112 and the distal shell-based electrode 104 can be used to sense ventricular electrical signals for sensing ventricular R waves. Electrodes 104 and 106 can be used to sense atrial electrical signals for sensing atrial P waves. Atrial and ventricular electrical signals can be analyzed to sense atrial and ventricular events. In some instances, the pacemaker 100 is a dual-chamber pacemaker configured to deliver atrial pacing pulses using the shell-based distal electrode 104 and proximal electrode 106, and ventricular pacing pulses via the tip electrode 102 and proximal electrode 106. Examples of dual-chamber intracardiac pacemakers incorporating the techniques disclosed herein for controlling ventricular sensing parameters are generally disclosed in U.S. Patent Application Publication No. 2019 / 0083800 (Yang et al.), which is incorporated herein by reference in its entirety.

[0039] Figure 1 and Figure 2 Instances of IMD and Figure 3 The pacemaker 100 is an illustrative example of a medical device configured to accumulate evidence of actual or potential oversensing of atrial events and / or cardiac potential signals as erroneous R waves according to the techniques disclosed herein, and to control ventricular sensing. However, these techniques are not limited to... Figures 1 to 3 The illustration shows an illustrative configuration of the sensing and pacing device and associated electrodes. In various instances, medical devices configured to perform the techniques disclosed herein may include leadless devices (such as housing-based electrodes) Figure 3 (As shown), a leadless pacemaker having an extension carrying one or more electrodes, or a medical device coupled to one or more medical leads configured to position ventricular pacing and sensing electrodes. Such examples may include external pacemakers coupled to one or more percutaneous medical leads.

[0040] Figure 4 This is a schematic diagram of a circuit system that can be enclosed within an IMD, which is configured to perform sensing and pacing using the techniques disclosed herein. Figure 4 The block diagram represents IMD 14 ( Figure 1 and 2 (For the purpose of explanation.) It should be understood that, attributable to Figure 4 The functions of the various circuits and components shown for performing ventricular pacing and sensing by monitoring evidence of oversensing can be similarly applied in... Figure 3 Implemented in an intracardiac pacemaker 100 or other medical device capable of delivering ventricular pacing pulses and sensing cardiac electrical signals.

[0041] The outer casing 15 is indicated as Figure 4The electrodes within the housing 15 are used for sensing cardiac electrical signals and, in some instances, for delivering cardiac electrical stimulation pulses, such as monopolar pacing pulses. The electronic circuitry enclosed within the housing 15 includes software, firmware, and / or hardware that collaboratively monitors cardiac electrical signals, determines when pacing therapy is needed, and delivers electrical pacing pulses to the patient's heart as needed, based on 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.

[0042] Power source 98 provides power to the circuitry of IMD 14, which, as needed, includes each of circuits 80, 82, 84, 86, and 88. Power source 98 may include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. The connection between power source 98 and each of other components 80, 82, 84, 86, and 88 should be determined according to... Figure 4 A general block diagram is provided, but is not shown for clarity. For example, power supply 98 may be connected to one or more charging circuits included in therapeutic delivery circuitry 84 to provide the power required to charge a holding capacitor included in therapeutic delivery circuitry 84, which discharges at appropriate times under the control of control circuitry 80 to generate and deliver pacing pulses. Power supply 98 is also connected to components of sensing circuitry 86 (such as sensing amplifiers, analog-to-digital converters, switching circuits, etc.), telemetry circuitry 88, and memory 82 to provide power to various circuits as needed.

[0043] Figure 4 The functional blocks shown represent the functionality included in IMD 14 and may include any discrete and / or integrated electronic circuitry components for implementing analog and / or digital circuitry capable of producing the functionality attributed herein to IMD 14 (or pacemaker 100). Various components may include application-specific integrated circuits (ASICs), electronic circuitry, processors (shared, dedicated, or grouped) executing one or more software or firmware programs, combinational logic circuitry, processors (shared, dedicated, or grouped) and memory for state machines, or other suitable components or combinations of components providing the described functionality. Given the disclosure herein, providing software, hardware, and / or firmware to perform the described functionality in the context of any modern cardiac medical device system is within the capabilities of those skilled in the art.

[0044] Control circuitry 80 communicates, for example, via a data bus with treatment delivery circuitry 84 and sensing circuitry 86, for sensing cardiac electrical signals and scheduling the delivery of cardiac electrical stimulation therapy in response to sensed cardiac events (e.g., P waves with atrial depolarization and R waves with ventricular depolarization, or their absence). Electrodes may be electrically coupled to treatment delivery circuitry 84 for delivering electrical stimulation pulses to the patient's heart and / or to sensing circuitry 86 for sensing cardiac electrical signals generated by the heart, which may include inherent signals generated by the heart in the absence of a pacing pulse to capture the heart (such as inherent P and R waves), and evoked response signals generated in response to a pacing pulse with sufficient energy to cause capture.

[0045] Sensing circuit 86 may include cardiac event detection circuitry, which may include one or more sensing amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components for detecting cardiac electrical events. Sensing circuit 86 may include two or more sensing channels for detecting cardiac electrical events from two or more sensing electrode vectors. Sensing circuit 86 may include switching circuitry for selectively coupling sensing electrode pairs from available electrodes to atrial channel 87 and ventricular channel 89. Switching circuitry may include a switching array, switching matrix, multiplexer, or any other type of switching device suitable for selectively coupling components of sensing circuit 86 to selected electrodes. For example, atrial signals may be received by atrial channel 87 via electrodes 20 and 22 of atrial leads 16. Figure 1 Furthermore, ventricular signals can be received by ventricular channel 89 via electrodes 32 and 34 of the ventricular leads. Figure 1 and Figure 2 ).

[0046] An atrial event detector may be included in atrial channel 87 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 ventricular channel 89 for detecting intrinsic R waves accompanying intrinsic ventricular depolarization using one or both of electrodes 32 and 34 carried by ventricular lead 18. Cardiac event sensing thresholds (such as P wave sensing thresholds or R wave sensing thresholds) may be automatically adjusted by sensing circuit 86 under the control of control circuit 80, for example, based on timing intervals and sensing thresholds determined by control circuit 80, stored in memory 82, and / or controlled by the hardware, firmware, and / or software of control circuit 80 and / or sensing circuit 86. For example, the R wave sensing threshold may be controlled after ventricular blanking period to initiate a threshold voltage (which may be based on previously sensed R wave amplitude), and then reduced according to a decay curve until a minimum sensing threshold is reached. The minimum R wave sensing threshold may be set as a programmed sensitivity setting of the ventricular channel. The sensitivity setting programmed to a voltage level typically in millivolts (e.g., in the range of 0.3 mV to 1.8 mV) is the minimum voltage level beyond which the ventricular channel senses an R wave, which can be a real R wave or a falsely sensed R wave, such as a P wave or H wave due to exceeding the R wave sensing threshold.

[0047] After detecting a cardiac electrical event based on a sensing threshold exceeding a limit, sensing circuit 86 can generate a sensing event signal that is passed to control circuit 80. For example, the atrial event detector in atrial channel 87 can generate a P-wave sensing event signal in response to a P-wave sensing threshold exceeding a limit occurring outside of any applied atrial blanking period. The ventricular event detector in ventricular channel 89 can generate an R-wave sensing event signal in response to an R-wave sensing threshold exceeding a limit. The sensing event signal generated by sensing circuit 86 is used by control circuit 80 to suppress scheduled pacing pulses and / or to set a pacing escape interval timer that controls the basic time interval for scheduling cardiac pacing pulses.

[0048] Combined with the following text Figure 5As described, the ventricular channel may further include an oversensing event detector configured to detect the time during which an R-wave sensing threshold may exceed the limit during the post-atrial time interval. The post-atrial time interval may be initiated in response to a P-wave sensing event signal generated by the atrial channel 87 or an atrial pacing pulse generated by the treatment delivery circuitry 84. The time during which the R-wave sensing threshold exceeds the limit during the post-atrial time interval may be used by the control circuitry 80 to accumulate evidence of oversensing, even when the R-wave sensing threshold exceedance during the atrial event detector period is not sensed by the ventricular event detector, for example due to the post-atrial ventricular blanking period, causing the sensing circuitry 86 not to generate an R-wave sensing event signal. In this way, and as further described below, the sensing circuitry 86 and the control circuitry 80 are configured to cooperatively detect and accumulate evidence of possible oversensing, regardless of whether actual oversensing of an atrial event or other event occurs, such as an H wave as a spurious R wave.

[0049] Each of the atrial channel 87 and the ventricular channel 89 can also generate a corresponding digital electrocardiogram (EGM) signal, which can be passed to the control circuitry 80 for further processing and analysis. Each channel 87 and 89 may include an input filter, preamplifier, analog-to-digital converter, and band-pass, low-pass, or high-pass filter for receiving atrial or ventricular signals from a corresponding pair of sensing electrodes, for generating a multi-bit digital EGM signal that can be passed to the control circuitry 80. In some instances, the control circuitry 80 can analyze the ventricular EGM signal to accumulate evidence of oversensing. The control circuitry 80 can determine ventricular signal characteristics during the post-atrial time interval, such as the maximum peak signal amplitude, the time of the maximum peak, and / or the R-wave sensing threshold exceedance time, based on the signal received from the oversensing event detector of the ventricular channel 89 and / or by processing and analyzing the ventricular EGM signal received from the ventricular channel 89. The control circuitry 80 can use such ventricular signal characteristics to accumulate evidence of oversensing and control ventricular sensing control parameters based on said evidence.

[0050] Control circuit 80 may include various timers or counters for counting various pacing escape intervals, such as atrioventricular (AV) pacing intervals, VV pacing intervals, AA pacing intervals, etc. Depending on the specific programmed pacing pattern, a sensed event signal may trigger or suppress pacing pulses. For example, a P-wave sensed event signal received from sensing circuit 86 may cause control circuit 80 to suppress scheduled atrial pacing pulses and schedule ventricular pacing pulses at programmed AV pacing intervals. If the AV pacing interval expires before control circuit 80 receives an R-wave sensed event signal from sensing circuit 86, control circuit 80 may control treatment delivery circuit 84 to deliver ventricular pacing pulses at the AV pacing interval following the sensed P wave, and in this way deliver ventricular pacing synchronized with the atria. If an R-wave sensed event signal is received from sensing circuit 86 before the AV pacing interval expires, the scheduled ventricular pacing pulse may be suppressed. The AV pacing interval controls the amount of time between pacing or sensed atrial events and ventricular pacing pulses to facilitate AV synchronization in atrial-tracking ventricular pacing patterns. However, when events that may be atrial pacing pulse artifacts, atrial induced response signals, intrinsic P waves, or H waves are oversensed as erroneous R waves by the ventricular event detector of the ventricular channel 89, ventricular pacing pulses may be suppressed, leading to ventricular pauses or ventricular arrest in pacemaker-dependent patients.

[0051] Therefore, control circuit 80 is configured to accumulate actual and / or potential oversensing evidence using the techniques disclosed herein to control R-wave sensing through ventricular channel 89 in a manner that avoids or minimizes the possibility of actual oversensing of atrial events and / or cardiac potential signals as false R-waves. For example, control circuit 80 may include a counter for counting event-time signals generated by sensing circuit 86, the event-time signals corresponding to R-wave sensing threshold exceedances during the post-atrial time interval. As further described below, the event-time signals may be generated by an oversensing event detector included in sensing circuit 86. Oversensing evidence can be accumulated by control circuit 80 by at least counting the number of event-time signals generated during the post-atrial time interval (e.g., during a predetermined number of ventricular cycles).

[0052] Medical devices configured to perform the techniques disclosed herein can be configured for delivering ventricular tachycardia pacing therapy, atrial synchronized ventricular pacing, rate-responsive pacing, cardiac resynchronization therapy (CRT), antitachycardia pacing therapy, or other pacing therapies, such as those via a His-Purkinje system or any part thereof, pacing the ventricle. The treatment delivery circuit 84 may include a charging circuit system, one or more charge storage devices, such as one or more holding capacitors, an output capacitor, and a switching circuit that controls the delivery of pacing pulses to a selected pacing electrode vector connected to the treatment delivery circuit 84 when the holding capacitor is charged and the output capacitor is discharged. The treatment delivery circuit 84 may include one or more pacing channels. In the example of IMD 14, the treatment delivery circuit 84 may include an atrial pacing channel and a ventricular pacing channel. Each pacing channel may include one or more holding capacitors, one or more switches, and an output signal line, the output signal line including at least one output capacitor for generating pacing pulses delivered by the corresponding atrial leads 16 (electrodes 20 and 22) or ventricular leads 18 (electrodes 32 and 34). Charging the holding capacitor to a programmed pacing voltage amplitude and discharging the capacitor for a programmed pacing pulse width can be performed by the treatment delivery circuit 84 according to control signals received from the control circuit 80. For example, the pacing timing circuit included in the control circuit 80 may include a programmable digital counter set by the microprocessor of the control circuit 80 for controlling a basic pacing time interval associated with various single-chamber or dual-chamber pacing modes, CRT, or anti-tachycardia pacing sequences. The microprocessor of the control circuit 80 may also set the amplitude, pulse width, polarity, or other characteristics of the cardiac pacing pulse, based on programmed values ​​stored in memory 82.

[0053] In some instances, IMD 14 can be configured to detect non-sinus tachycardia and deliver anti-tachycardia pacing (ATP). Control circuitry 80 can determine cardiac event intervals, such as the PP interval between consecutive P-wave sensed event signals received from sensing circuitry 86 and / or the RR interval between consecutive R-wave sensed event signals received from sensing circuitry 86. These intervals can be compared to tachycardia detection intervals to detect non-sinus tachycardia. Tachycardia can be detected in a given cardiac chamber based on a threshold number of detected tachycardia detection intervals. In response to the detection of atrial or ventricular tachycardia, control circuitry 80 can control therapeutic delivery circuitry 84 to deliver ATP.

[0054] In some instances, in addition to the low-voltage therapeutic circuitry system for generating low-voltage pacing pulses, the therapeutic delivery circuitry 84 may include a high-voltage therapeutic circuitry system for generating high-voltage impulse pulses. In response to the detection of atrial or ventricular tachycardia or fibrillation, the control circuitry 80 may control the therapeutic delivery circuitry 84 to deliver a cardioversion / defibrillation (CV / DF) impulse. The high-voltage therapeutic circuitry system may include a high-voltage capacitor and a high-voltage charging circuitry system for generating and delivering the CV / DF impulse pulse.

[0055] Control parameters for sensing cardiac events and controlling pacemaker delivery in control circuit 80 can be programmed into memory 82 via telemetry circuit 88. Telemetry circuit 88 includes a transceiver and antenna for communicating with external device 50 using radio frequency communication or other communication protocols, as described above. Figure 1 As described above. Under the control of the control circuit 80, the telemetry circuit 88 can receive downlink telemetry from the external device 50 and send uplink telemetry to the external device 50. In some cases, the telemetry circuit 88 can be used to transmit and receive communication signals to another medical device implanted in the patient's body.

[0056] Figure 5 It can be included in Figure 4 A conceptual diagram of the circuitry in the ventricular channel 89 of the sensing circuitry 86 is shown. In this example, the ventricular channel 89 includes a pre-filter / amplifier 172, an analog-to-digital converter (ADC) 174, a rectifier / amplifier 175, and a ventricular event detector 176. The pre-filter / amplifier circuitry 172 receives ventricular signals from ventricular pacing and sensing electrodes 32 and 34 (or from one of electrodes 32 or 34 mated to the housing 15). It should be appreciated that in other configurations, other available electrodes may be selected to receive ventricular electrical signals generated by the patient's heart. The pre-filter / amplifier circuitry 172 may include a low-pass filter for filtering out high-frequency noise or artifacts and amplifies the filtered signal, which is then passed to the ADC 174. The ADC 174 passes the digitized signal to the rectifier / amplifier circuitry 175, which may include a rectifier, a band-pass filter, and / or an amplifier for passing the rectified signal to the ventricular event detector 176.

[0057] The ventricular event detector 176 may include a comparator, a sensing amplifier, or other detection circuitry configured to detect an R-wave sensing threshold exceeding a limit via ventricular signals. In response to an R-wave sensing threshold exceeding a limit, the ventricular event detector 176 generates an R-wave sensing event signal 178 output to control circuitry 80. The ventricular event detector 176 may receive a blanking signal 177, which may be controlled by a timer in sensing circuitry 86 or control circuitry 80 and set according to sensing control parameters received from control circuitry 80. As described below, control circuitry 80 may enable a post-atrial ventricular blanking period in response to accumulated evidence of oversensing, in order to reduce the likelihood of oversensing atrial events and / or cardiac potential signals from the His bundle or bundle branches. For example, the ventricular event detector 176 may apply a post-atrial blanking interval to the ventricular signal received from rectifier / amplifier 175 to prevent the ventricular event detector 176 from generating an R-wave sensing event signal 178 during the post-atrial ventricular blanking interval. Based on the possibility of R-wave sensing threshold exceeding the limit during the post-atrial ventricular blanking period, the ventricular event detector 176 is prevented from generating erroneous R-wave sensing event signals. In other instances, the post-atrial blanking period can be imposed by control circuitry 80 to ignore any R-wave sensing event signals generated by the ventricular event detector 176 and received during the post-atrial blanking period.

[0058] The blanking signal 177 can be configured to set the start time, duration, or end time for blanking the ventricular event detector 176 during a blanking period enabled in response to a sensed or paced atrial event. In some instances, the blanking signal 177 received by the event detector 176 or generally the ventricular channel 89 may include multiple blanking signals applied to one or more components of the ventricular channel 89 such that the event detector 176 is effectively disabled from sensing an event during post-atrial blanking and re-enabled to sense an event after the post-atrial blanking period ends. In various instances, a blanking period may be applied by temporarily disabling or disconnecting the circuitry of the ventricular channel 89 during post-atrial ventricular blanking or otherwise suppressing the generation of an R-wave sensed event signal by the event detector 176.

[0059] In some instances, ventricular channel 89 may include an oversensing event detector 180, which may include a comparator, a sensing amplifier, or other detection circuitry that detects an R-wave sensing threshold exceeding a limit of the ventricular signal received from rectifier / amplifier 175. The oversensing event detector 180 may receive input from rectifier / amplifier circuitry 175. The oversensing event detector 180 may include the same or similar circuitry as the ventricular event detector 176 configured to detect an R-wave sensing threshold exceeding a limit. In other instances, the oversensing event detector 180 may receive input from ADC 174 and include rectifier / amplifier circuitry that may be the same or similar to rectifier / amplifier circuitry 175. In various instances, input to the oversensing event detector 180 may be received directly from electrodes 32 and 34, or from any point in the pre-filter / amplifier 172, ADC 174, rectifier / amplifier circuitry 175, or ventricular event detector 176. Therefore, the oversensing event detector 180 may include circuitry for filtering, amplifying, digitizing, and / or rectifying based on the input source. One or both of the ventricular event detector 176 or the oversensing event detector 180 may include peak amplitude detector circuitry for detecting the peak amplitude and / or the timing of the peak amplitude of cardiac electrical signal events that exceed the corresponding R-wave sensing threshold.

[0060] However, when the post-atrial ventricular blanking period is enabled and applied by the ventricular event detector 176 (or control circuit 80), the oversensing event detector 180 does not apply the post-atrial ventricular blanking period. Instead, the oversensing event detector 180 can be enabled to sense R-wave sensing threshold exceedances occurring during the post-atrial ventricular blanking period. However, the oversensing event detector 180 does not generate an R-wave sensing event signal in response to an R-wave sensing threshold exceedance. Instead, the oversensing event detector 180 can transmit an event time signal 186, and, at least in some instances, an event peak amplitude signal 188 determined based on the event signal exceeding the R-wave sensing threshold, to the control circuit 80.

[0061] In some instances, the oversensing event detector 180 may generate an event time signal 186 corresponding to an R-wave sensing threshold exceeding the limit, wherein the event time signal 186 coincides with the time of the detected R-wave sensing threshold exceeding the limit. Alternatively, the oversensing event detector 180 may generate an event time signal whose peak amplitude coincides with the time of the event signal that exceeds the R-wave sensing threshold. Figure 5The event time signal that coincides with the peak amplitude corresponding to the R-wave sensing threshold is represented as peak time signal 187. Peak time signal 187 can be the time of the maximum peak amplitude of the rectified cardiac electrical signal detected during the post-atrial time interval. The maximum peak amplitude can be detected during the post-atrial time interval after the R-wave sensing threshold is exceeded. The post-atrial time interval can be the same as or different from the post-atrial ventricular blanking period applied by event detector 176.

[0062] In the various examples described herein, one or both of the event time signal 186 and the peak time signal 187 may be transmitted to the control circuit 80. The control circuit 80 accumulates evidence of oversensing based on the event time signal 186, the peak time signal 187, and / or the event amplitude signal 188. In other examples, the control circuit 80 may receive a digitized ventricular EGM signal 185 from the ventricular channel 89 and process and analyze the EGM signal 185 for detecting and determining evidence of oversensing, such as the time to exceed the R-wave sensing threshold after an atrial event and / or the maximum peak amplitude and peak time of the EGM signal after an atrial event or after the event time signal 186.

[0063] In some instances, the oversensing event detector 180 may receive a timing P-wave sensing event signal 183 from the atrial channel 87, indicating a sensed P wave. Alternatively, the atrial channel 87 may transmit the P-wave sensing event signal to the control circuitry 80 each time a P-wave sensing threshold is exceeded, and the control circuitry 80 may transmit the P-wave sensing event signal 183 to the oversensing event detector 180. The oversensing event detector 180 may additionally receive an atrial pacing signal 184 (from the treatment delivery circuitry 84 or from the control circuitry 80), indicating the timing of an atrial pacing pulse generated and delivered by the treatment delivery circuitry 84. The oversensing event detector 180 may be configured to detect when an R-wave sensing threshold exceeding the ventricular signal occurs during a post-atrial time interval extending from the P-wave sensing event signal or from the atrial pacing pulse. The post-atrial time interval may correspond to a post-atrial ventricular blanking period that may be applied by the ventricular event detector 176. In other instances, the post-atrial time interval can be a programmable time interval that can begin and / or end at a time different from the post-atrial ventricular blanking period. For example, the post-atrial time interval can be longer than the post-atrial ventricular blanking period. As an example, the post-atrial ventricular blanking period can be set to 80 milliseconds (ms), and the post-atrial time interval can be set to 120 ms. The oversensing event detector 180 can be enabled to detect R-wave sensing threshold exceedances only during the post-atrial time interval in order to generate an event time signal 186 (and / or a peak time signal 187 and / or an event peak amplitude signal 188) received by the control circuitry 80 for accumulating evidence of oversensing.

[0064] In this way, even when the erroneous R-wave sensed event signal is not generated by the ventricular event detector 176, oversensing evidence indicating the possibility that the ventricular event detector 176 is erroneously sensing atrial events and / or cardiac potential signals can be accumulated. For example, an oversensing event detector 180 can detect an R-wave sensing threshold exceedance during the overlap of the post-atrial time interval and the post-atrial ventricular blanking period. The oversensing event detector 180 can generate an event time signal 186 instead of the R-wave sensed event signal 178 generated by the ventricular event detector 176. Oversensing evidence can be added based on the event time signal 186 even when no atrial event or cardiac potential signal is actually oversensed by the ventricular event detector 176 or used by the control circuit 80 to suppress ventricular pacing pulses.

[0065] When the R-wave sensing threshold is set to the same amplitude (which may decay over time) as the R-wave sensing threshold used by the ventricular event detector 176, the oversensing event detector 180 can be controlled to detect R-wave sensing threshold overruns in cardiac electrical signals. In this way, the oversensing event detector 180 can identify events that would be sensed by the ventricular event detector 176 when the atrial event detector 176 is disabled. However, in other instances, the oversensing event detector 180 can be controlled to detect R-wave sensing threshold overruns when the R-wave sensing threshold is set differently from the R-wave sensing threshold applied by the ventricular event detector 176 (e.g., higher or lower). For example, the oversensing event detector 180 can be set to a different amplitude to use a different R-wave sensing threshold than the ventricular event detector 176 to determine the frequency of sensed (or unsenseable) events. For example, when the R-wave sensing threshold applied by the oversensing event detector 180 is lower than the R-wave sensing threshold applied by the ventricular event detector 176, if the R-wave sensing threshold decreases, the control circuit 80 can determine the likelihood of an oversensing event during the post-atrial time interval using the ventricular event detector 176. The control circuit 80 can adjust the R-wave sensing threshold used by the oversensing event detector 180 to be different from the R-wave sensing threshold temporarily applied by the ventricular event detector 176 to test possible ventricular sensing control parameters, such as sensitivity settings, to predict whether oversensing is expected to occur before actual adjustment of the ventricular sensing control parameters.

[0066] Figure 6 This means that it can be done by Figure 5A timing diagram 150 of the signals generated by the ventricular event detector 176 and the oversensing event detector 180. An atrial event signal 152 can be received by the ventricular channel 89 to set a post-atrial blanking period 160 applied by the ventricular event detector 176 (when blanking is enabled) and a post-atrial time interval 162 applied by the oversensing event detector 180. The atrial event signal 152 can correspond to an inherent P wave sensed by the sensing circuit 86 or an atrial pacing pulse generated by the treatment delivery circuit 84.

[0067] Ventricular signal 153 represents the rectified signal passed from rectifier / amplifier 175 to ventricular event detector 176 and oversensing event detector 180. Ventricular signal 153 includes early event signal 154 and late event signal 156. Early event signal 154, occurring within the post-atrial time interval 162, may be an atrial event signal corresponding to atrial event 152, which can be oversensed by ventricular event detector 176 if post-atrial ventricular blanking period 160 is disabled. If blanking period 160 is disabled, ventricular event detector 176 may generate erroneous R-wave sensing event signal 166, which can cause treatment delivery circuitry 84 to suppress ventricular pacing pulses. However, when post-atrial ventricular blanking 160 is enabled, any R-wave sensing threshold overruns occurring during post-atrial ventricular blanking period 160 are ignored by ventricular event detector 176, resulting in no R-wave sensing event signal being generated. In other instances, the ventricular event detector 176 may generate an R-wave sensed event signal 166 during the blanking period 160, but the control circuit 80 applies the blanking period 160 and ignores any R-wave sensed event signals received during the blanking period 160 in order to control ventricular pacing (e.g., based on the R-wave sensed event signal 166 without suppressing or scheduling the ventricular pacing pulse).

[0068] An oversensing event detector 180 is enabled to detect R-wave sensing threshold exceedances during the post-atrial time interval 162. After the post-atrial time interval 162 expires, the oversensing event detector 180 can be disabled or hidden until the next atrial event triggers a new post-atrial time interval. In this way, the oversensing event detector 180 can generate an event time signal, such as event time signal 164, only during the post-atrial time interval 162. The event time signal 184 is triggered in response to a sensed P wave, such as event signal 183 received from the atrial channel 87 (or control circuit 80). Figure 5The atrial post-atrial time interval 162 can be set to a first duration, such as 80 ms. When the atrial event 152 is an atrial pacing pulse, the atrial post-atrial time interval 162 can be set to a second duration longer than the first duration, such as 110 ms. The atrial event signal 154 present in the ventricular signal 153 may occur relatively later after the atrial pacing pulse than after the sensed P wave, due to the delay between the delivered pacing pulse and the electrical depolarization of the atrial myocardial tissue.

[0069] When ventricular signal 153 exceeds the R-wave sensing threshold 157 during the post-atrial time interval 162, the oversensing event detector 180 generates an event time signal 164 used by the control circuit 80 to accumulate oversensing evidence, such as a count of the event time signals generated by the oversensing event detector 180. The control circuit 80 may ignore the event time signal 164 to control ventricular pacing or determine ventricular rate or rhythm. For example, the control circuit 80 may accumulate oversensing evidence by incrementing the value of the oversensing event counter each time it receives the event time signal 164 from the oversensing event detector 180. The control circuit 80 may use the accumulated oversensing evidence, such as the value of the oversensing event counter, to determine whether an oversensing criterion is met based on the number of event time signals generated by the oversensing event detector 180 (within the post-atrial time interval) over a predetermined number of ventricular cycles. When the oversensing criteria are met, if the post-atrial ventricular silencing period 160 is disabled, given the currently programmed ventricular sensitivity settings and any other sensing threshold control parameters used to control the R-wave sensing threshold 157, oversensing of the ventricular event detector 176 is highly probable.

[0070] The control circuit 80 uses the event time signal 164 to control the ventricular sensing control parameters applied to the ventricular event detector 176, such as enabling or disabling the post-atrial ventricular blanking period 160, setting the end time 165 of the post-atrial ventricular blanking period 160 (e.g., based on the timing of the event time signal 164 after the atrial event 152), and / or adjusting the ventricular sensitivity setting used to control the R-wave sensing threshold 157. Figure 6The R-wave sensing threshold 157 shown can be equal to the ventricular sensitivity setting, which is the sensing floor level or minimum voltage amplitude that adjusts the automatic adjustment of the R-wave sensing threshold. The R-wave sensing threshold 157 can be set to a starting value after a ventricular pacing pulse or a sensed R-wave, and can be reduced to the ventricular sensitivity setting based on one or more decay rates or step size differences, such as to 0.075, 0.1, 0.3, 0.45, 0.6, 0.9, or 1.2 mV or other programmed values. As described below, the control circuitry 80 can be configured to adjust the ventricular sensitivity setting, the end time 165 of the post-atrial ventricular blanking period 160, and / or enable or disable the post-atrial ventricular blanking period 160 based on accumulated evidence of oversensing received from the oversensing event detector 180 (such as the event timing signal 164). In addition to the event time signal 164 indicating the time during which the R-wave sensing threshold exceeds the limit during the post-atrial time interval 162, the oversensing event detector 180 may include a peak detector for determining the maximum peak amplitude 155 of the event 154 that exceeds the limit R-wave sensing threshold 157 and the time of the peak amplitude 155. The oversensing event detector 180 may generate an amplitude signal (signal 188, Figure 5 The amplitude signal indicates the maximum peak amplitude of 155 and / or the peak time signal (signal 187). Figure 5 As described below, in addition to other evidence of accumulated oversensing, control circuitry 80 may also use the maximum peak amplitude 155 to determine whether to adjust the ventricular sensitivity setting and / or enable the post-atrial ventricular blanking period 160 to reduce the likelihood of oversensing in the ventricular channel 89. In some instances, the time of the maximum peak amplitude may be used to set the end time of the post-atrial ventricular blanking period 160.

[0071] In some instances, the cardiac potential signal 159 may be present in the ventricular signal 153. The cardiac potential signal 159 may be a His bundle potential signal or an H wave, and may occur 30 to 70 ms after the atrial event 152 and 20 to 50 ms before the actual R wave. The potential signal 159 may occur during the post-atrial time interval 162, causing the oversensing event detector 180 to generate an event time signal 169 indicating the time at which the R-wave sensing threshold of the oversensing signal may potentially exceed if the post-atrial ventricular blanking period 160 is disabled or shortened. When the ventricular blanking period 160 is enabled and the time later than the cardiac potential signal 159 expires, the ventricular event detector 176 does not generate the R-wave sensing event signal 163 (as indicated by the dashed line).

[0072] The oversensing event detector 180 can generate an amplitude signal indicating the maximum peak amplitude 161 of the potential signal 159. As described above, the oversensing event detector 180 can additionally or alternatively generate a peak time signal indicating the time of the maximum peak 161 of the potential signal 159. The control circuit 80 can accumulate oversensing evidence in response to receiving the event time signal 169 (and / or the peak amplitude and / or peak time signal), and use the accumulated oversensing evidence and / or event amplitude information to adjust ventricular sensing control parameters, for example, by increasing the ventricular sensitivity setting to be greater than the amplitude of the potential signal 159, and / or enabling or extending the atrial-ventricular blanking period 160 so that the atrial event 152 occurs later than the time of the potential signal 159. The control circuit 80 can adjust the duration or end time of the post-atrial time interval 162 based on the timing of the latest event time signal 159 occurring during the post-atrial time interval 162. In various instances, the oversensitized event time can be determined from the atrial event signal to the latest event time signal during the post-atrial time interval 162 for each of multiple cardiac cycles. The end time of the post-atrial ventricular silencing period 160 and / or the post-atrial time interval 162 can be adjusted based on a metric of the oversensitized event time, such as the average, median, nth longest, longest, or other metric of the timing of the latest event time signals within one or more cardiac cycles.

[0073] Although the early signal 154, which corresponds to atrial event 152 and potential signal 159, can be shown in ventricular signal 153, it should be recognized that in various cases, one, both, or neither of signals 154 and 159 may be present in ventricular signal 153 for a given cardiac cycle. When two or more signals exceed the R-wave sensing threshold 157 during the post-atrial time interval 162, control circuitry 80 may accumulate evidence of oversensing, for example as a count of the event time signals, in response to one or all event time signals generated by oversensing event detector 180 during a given cardiac cycle. Figure 6 In one example, the control circuit 80 may accumulate oversensing evidence, for instance, by incrementing the oversensing event counter by one in response to only one event time signal 164 or 169, or by incrementing the oversensing evidence by two in response to each event time signal 164 and 169.

[0074] A late event 156 of ventricular signal 153 exceeds the R-wave sensing threshold 157. The R-wave sensing threshold 157 can be equal to the ventricular sensitivity setting at this time in the ventricular circulation because earlier events 154 and 159 were not sensed by ventricular event detector 176 and are not used to reset the R-wave sensing threshold amplitude to its initial value based on the sensed event amplitude. Late event 156 occurs outside the post-atrial ventricular blanking period 160 and after the post-atrial time interval 162. Ventricular event detector 176 generates an R-wave sensing event signal 168, which is used by control circuitry 80 to control ventricular pacing, for example, suppressing scheduled ventricular pacing pulses and / or initiating lower-rate ventricular pacing intervals. Oversensing event detector 180 can be disabled or can not receive ventricular signal 153 outside the post-atrial time interval 162. Therefore, oversensing event detector 180 does not generate an event time signal in response to event 156 exceeding the R-wave sensing threshold 157.

[0075] In some instances, control circuitry 80 may determine the peak amplitude 158 of a late event (such as event 156) that causes the event signal 168 to be sensed by the ventricular event detector 176 to generate R-wave sensing. Control circuitry 80 may use the peak amplitude 158 to determine the magnitude of the R-wave amplitude. As described below, the magnitude of the R-wave amplitude may be used to determine whether to adjust the ventricular sensitivity setting when the oversensitivity evidence criteria are met. In other instances, ventricular event detector 176 may include peak detector circuitry and be configured to detect the peak amplitude 158 of the late event 156 associated with the R-wave sensing event signal 168. Ventricular event detector 176 may generate a peak amplitude signal, which, indicating the amplitude of the late event 156 (e.g., in volts or millivolts), is passed to control circuitry 80. In other instances, a peak detector implemented in the oversensing event detector 180 may be enabled to determine the peak amplitude of both early and late events within and outside the post-atrial time interval 162, such that the oversensing event detector 180 may transmit a peak amplitude signal indicating the peak amplitude 158 of the late event 156 to the control circuit 80.

[0076] It should be understood that, although Figure 4 and Figure 5 An example configuration of circuitry is depicted for detecting R-wave sensing threshold overshoot and generating associated time and amplitude signals for accumulating evidence of oversensing and adjusting ventricular sensing control parameters. However, the functionality disclosed herein can be implemented in various configurations in which one or more circuits and / or processors are configured to collaboratively perform the functionality described herein and attributed to the IMD 14 or pacemaker 100.

[0077] When post-atrial ventricular concealment 160 is disabled, an R-wave sensing threshold exceedance during (or after) the post-atrial time interval 162 will cause the ventricular event detector 176 to generate an R-wave sensing event signal (e.g., 163, 166, or 168). Control circuitry 80 maintains the scheduled ventricular pacing pulse in response to receiving the R-wave sensing event signal. The ventricular pacing pulse can be scheduled when the AV pacing interval or VV pacing interval expires. When post-atrial ventricular concealment is enabled, only an R-wave sensing threshold exceedance outside the post-atrial ventricular concealment period 160 (e.g., event 156) can cause control circuitry 80 to maintain the scheduled ventricular pacing pulse. The R-wave sensing threshold exceedance may or may not occur within the post-atrial time interval 162. For example, when the post-atrial time interval 162 is longer than the post-atrial blanking period 160, the ventricular event detector 176 may generate an R-wave sensing event signal in response to an R-wave sensing threshold exceeding the limit during the non-overlapping portion 167 of the post-atrial time interval 162 and the post-atrial blanking period 160. The R-wave sensing event signal can cause the control circuit 80 to maintain the scheduled ventricular pacing pulse. The oversensing event detector 180 may generate an event time signal in response to an R-wave sensing threshold exceeding the limit during the non-overlapping portion 167 of the post-atrial time interval 162 and the post-atrial blanking period 160. The event time signal during the non-overlapping portion 167 causes the control circuit 80 to accumulate evidence of oversensing. Therefore, an R-wave sensing threshold exceeding the limit during the post-atrial time interval 162, but outside the post-atrial ventricular blanking period, may result in maintaining the scheduled ventricular pacing pulse and detecting evidence of oversensing by the control circuit 80. The control circuit 80 may use the oversensing evidence accumulated during the non-overlapping portion 167 to extend the post-atrial ventricular blanking period 160 later than the event time signal received during the non-overlapping portion 167 and / or increase the ventricular sensitivity setting to avoid sensing events during the non-overlapping portion 167.

[0078] Figure 7 This is a flowchart 200 of a method, according to one example, that can be performed by a medical device (such as IMD 14 or pacemaker 100) for accumulating evidence of oversensing and adjusting ventricular sensing control parameters. At block 202, control circuitry 80 can determine when an R-wave sensing threshold exceedance has occurred. This determination can be based on an event time signal 186 received from an oversensing event detector 180 and / or an R-wave sensing event signal 178 received from a ventricular event detector 176. In some instances, at block 202, an R-wave sensing threshold exceedance occurring during a post-atrial time interval is identified for detecting evidence of oversensing. For detection based on... Figure 7 The purpose of the method for oversensing evidence is to ignore the R-wave sensing threshold outside the post-atrial time interval that occurs at box 202.

[0079] At block 204, control circuitry 80 can determine the time interval from the previous atrial event to the occurrence of an R-wave sensing threshold overshoot (or peak amplitude time), and determine whether the determined time interval is less than an oversensing event time interval threshold. The oversensing event time interval threshold can correspond to a post-atrial time interval, for example, Figure 6 During the post-atrial time interval 162, an R-wave sensing threshold exceedance can be caused by an atrial event (sensing or pacing) or a cardiac potential signal. If an R-wave sensing threshold exceedance occurs slightly later than the oversensing event time interval threshold, for example, outside of the post-atrial time interval 162, control circuitry 80 returns to block 202 to wait for the next R-wave sensing threshold exceedance. R-wave sensing threshold exceedances later than the oversensing event time interval threshold of the previous P-wave sensing event signal or the delivered atrial pacing pulse are not counted as evidence of possible oversensing.

[0080] In some instances, the control circuit 80 may be based on receiving an event timing signal 186 from the oversensing event detector 180 (e.g., Figure 5 (As shown) to determine that the time from an atrial event (sensing or pacing) to an R-wave sensing threshold exceeding the limit is less than an oversensing event time interval threshold. An oversensing event detector 180 can be enabled to generate an event time signal 186 only during the post-atrial time interval. Therefore, when control circuitry 80 receives an event time signal from oversensing event detector 180, the corresponding R-wave sensing threshold exceeding the limit is within the oversensing event time interval threshold at block 206. In some cases, when post-atrial ventricular blanking is not enabled or when the post-atrial time interval is longer than the post-atrial ventricular blanking period, control circuitry 80 can also receive an R-wave sensing event signal from ventricular event detector 176 during the post-atrial time interval. However, the event time signal 186 from oversensing event detector 180 is evidence of whether or not R-wave sensing has occurred due to possible or actual oversensing. If no event time signal is received from the oversensing event detector 180, but an R-wave sensing event signal is received from the ventricular event detector 176 at block 202, the control circuit 80 can determine that the R-wave sensing threshold exceeds the oversensing event time interval threshold and return to block 202.

[0081] In some instances, the oversensing event interval threshold applied at box 206 may differ from the threshold applied when the preceding atrial event is a sensed P wave, compared to when the current atrial event is an atrial pacing pulse. A longer oversensing event interval threshold can be applied when the preceding atrial event that triggers the threshold is a pacing pulse, because there is a delay between the delivered atrial pacing pulse and the induced atrial depolarization. For example, when the preceding atrial event is a sensed P wave, the oversensing event interval threshold, or post-atrial interval, may be set to 70 ms to 100 ms or approximately 80 ms. When the preceding atrial event is an atrial pacing pulse, the interval threshold, or post-atrial interval, may be set to 100 ms to 120 ms or approximately 110 ms.

[0082] In response to determining that the time from an atrial event to a detected R-wave sensing threshold exceedance is less than an oversensing event time interval threshold, control circuitry 80 detects evidence of oversensing at box 208. The detected evidence of oversensing may or may not correspond to an actual oversensing event that caused the ventricular event detector 176 to generate an erroneous R-wave sensing event signal. When postventricular blanking is enabled and the R-wave sensing threshold exceedance occurs during the post-atrial ventricular blanking period, the evidence of oversensing detected at box 208 is evidence of a possible oversensing event, but oversensing may not actually occur or interfere with ventricular pacing control. The evidence of oversensing suggests that oversensing may occur or is predicted to occur if postventricular blanking is disabled.

[0083] At blocks 212 and 214, control circuitry 80 may determine whether accumulated evidence of oversensing meets oversensing criteria. In one instance, control circuitry 80 may determine whether evidence of oversensing (e.g., R-wave sensing threshold) of cardiac electrical signals exceeding limits is detected for a threshold number of consecutive ventricular cycles (or consecutive atrial sensing and / or atrial pacing events following a threshold number) during a post-atrial time interval. For example, control circuitry 80 may determine whether evidence of oversensing is detected for at least three, at least five, or other selected numbers of consecutively detected R-wave sensing threshold exceedances within a post-atrial time interval. When infrequent or intermittent evidence of oversensing is detected based on isolated R-wave sensing threshold exceedances during a post-atrial time interval, accumulated evidence of oversensing may be considered insufficient to respond by adjusting ventricular sensing control parameters. Infrequent oversensing atrial events or cardiac potential signals may not interfere with pacing control in a clinically significant manner, making adjustments to ventricular sensing control parameters that may reduce the reliability of true R-wave sensing potentially unjustifiable. In some cases, intermittent or infrequent oversensing evidence detection can be associated with intermittent or non-continuous non-cardiac noise or other signal artifacts, which may not require adjustment of ventricular sensing control parameters.

[0084] When the oversensing evidence counter increases during the post-atrial time interval following Z consecutive atrial events in response to an R-wave sensing threshold exceeding a certain limit, the control circuit 80 can detect Z consecutive cycles of oversensing evidence. When post-atrial ventricular concealment is enabled, the threshold number Z of consecutive cycles of detected oversensing evidence can differ from when post-atrial ventricular concealment is disabled. When post-ventricular concealment is enabled, oversensing evidence is less likely to cause ventricular pacing pauses. Therefore, a higher number of consecutively detected oversensing evidence may be required before performing any additional analysis or taking any further corrective action. However, when post-atrial ventricular concealment is disabled, oversensing of atrial events can cause ventricular pacing pauses. Therefore, the number of consecutive cycles of detected oversensing evidence can be relatively low, for example, two consecutive cycles, to allow the control circuit 80 to take more immediate corrective action by adjusting one or more ventricular sensing control parameters.

[0085] When oversensing evidence is detected at box 212 for at least Z consecutive ventricular cycles, for example, during at least Z consecutive post-atrial time intervals, control circuit 80 may apply additional oversensing evidence criteria at box 214. For example, control circuit 80 may additionally require oversensing evidence for Y cycles where at least X recent cardiac cycles have been detected. To illustrate, control circuit 80 may determine that the oversensing criteria are met at box 214 in response to determining that at least six out of twelve R-wave sensing threshold exceedances are detected as oversensing evidence, and that at least three are detected consecutively. As noted above, these thresholds for X out of Y cardiac cycles and at least Z consecutive oversensing evidence detections in oversensing evidence detection may be defined differently for when post-atrial ventricular concealment is enabled and when post-atrial ventricular concealment is disabled. The oversensing criteria to be applied at box 214 does not necessarily require generating an actual spurious R-wave sensing event signal when oversensing evidence is detected. As described above, oversensing criteria can be detected and accumulated at box 208, for example, as a count of R-wave sensing threshold crossovers within the post-atrial time interval. Oversensing criteria can be detected even when the ventricular event detector 176 applies a post-atrial ventricular blanking period to the ventricular signal, thereby excluding oversensing of event signals that may occur during the blanking period.

[0086] When the oversensing criterion is met at box 214, control circuitry 80 may enable post-atrial ventricular blanking at box 216. In some cases, post-atrial ventricular blanking may already be enabled, and if so, it remains enabled. In other cases, post-atrial ventricular blanking may not currently be enabled, and accumulated evidence of oversensing ensures that post-atrial ventricular blanking can be enabled regardless of whether actual oversensing occurs, to avoid or minimize the possibility of oversensing by ventricular event detector 176.

[0087] The post-atrial ventricular blanking period can be set to a fixed value or can be adjusted based on determining the time from the P-wave sensed event signal or atrial pacing pulse to the R-wave sensed threshold identified as evidence of oversensing. For example, a default maximum post-atrial ventricular blanking period can be enabled; however, if the time interval from the previous atrial event to the R-wave sensed threshold identified as evidence of oversensing is greater than or less than a safe interval of the default maximum blanking period, the blanking period can be shortened. The blanking period can be shortened by a predetermined reduction. For example, a maximum blanking period of 120 ms can be shortened to 110 ms or 100 ms, provided that the post-atrial ventricular blanking period is at least longer than the time of the oversensing evidence event following the atrial event, e.g., later than the time signal of the oversensing event following the atrial event. In other instances, the post-atrial ventricular blanking period can be reduced from the maximum to an interval that is a predetermined safe interval (e.g., 10 to 30 ms) or a predetermined percentage longer than the time interval from the most recent previous atrial event to the event detected as evidence of oversensing. This time interval can be determined by control circuitry 80 at block 204, for example, in response to an event timing signal received from oversensing event detector 180. Figure 5 ).

[0088] In other instances, control circuitry 80 can determine multiple A-OS (atrial-to-oversensing event) time intervals between an atrial event and a subsequent R-wave sensing threshold identified as evidence of oversensing. Longer A-OS time intervals can be determined when, for example, two events associated with an atrial event and two events associated with a cardiac potential signal occur within a post-atrial time interval. Control circuitry 80 can determine a maximum A-OS time interval at block 216 in response to meeting oversensing criteria. The maximum A-OS time interval can be determined from detected evidence of oversensing that contributes to meeting the oversensing criteria at block 214. Control circuitry 80 can set a post-atrial ventricular blanking period at block 216 based on the maximum A-OS time interval. For example, the post-atrial ventricular blanking period can be set to be equal to or greater than a predetermined safety interval or a predetermined percentage longer than the maximum A-OS time interval. Therefore, the post-atrial ventricular blanking period can be a variable duration and can be limited to some maximum permissible blanking period, such as a maximum of 120 or 130 ms.

[0089] When post-atrial ventricular blanking is enabled at box 216, two different blanking periods can be applied by the ventricular event detector 176. A shorter blanking period can be initiated in response to the receipt of an event signal sensed by a P wave, and a longer blanking period can be initiated in response to the delivery of an atrial pacing pulse. For example, the post-atrial ventricular blanking period set in response to the event signal sensed by a P wave can be 80 ms, and the blanking period set in response to an atrial pacing pulse can be 110 ms, although shorter or longer blanking periods can be selected and can be customized for a given patient. As described above, each of the post-atrial sensed event ventricular blanking period and the post-atrial pacing event ventricular blanking period can be set based on the A-OS time interval determined after atrial P wave sensing and after atrial pacing pulse, respectively.

[0090] When the oversensing criterion is not met at box 214, control circuitry 80 can disable post-atrial ventricular blanking at box 218. If post-ventricular blanking is enabled and applied via ventricular event detector 176, but the accumulated evidence of oversensing fails to meet the oversensing criterion at box 214, post-atrial ventricular blanking can be disabled at box 218, where the reasonably low risk of an event signal of erroneous R-wave sensing is generated by ventricular event detector 176. When oversensing is determined to be unlikely, disabling post-atrial ventricular blanking based on the oversensing criterion not being met at box 214 allows R-wave sensing to improve the reliability of R-wave sensing for pacing control and rhythm detection for a larger portion of the ventricular circulation. For example, being able to sense R-waves for a larger portion of the ventricular circulation can improve the detection of rapid ventricular rhythms such as ventricular tachycardia or fibrillation. In some cases, when it is determined that the oversensitivity criterion is not met at box 214, post-atrial ventricular demise may have been disabled. In such cases, post-atrial ventricular demise remains disabled at box 218.

[0091] After enabling or disabling post-atrial ventricular concealment at one of boxes 216 or 218, control circuitry 80 returns to box 202 to await the next R-wave sensing threshold exceedance. The process of flowchart 200 can be executed periodically or continuously in response to each R-wave sensing threshold exceedance. Each time the oversensing criterion is met, post-atrial ventricular concealment is enabled or remains enabled. Each time the oversensing criterion is not met, post-atrial ventricular concealment is disabled or remains disabled. The frequency of enabling and disabling post-atrial ventricular concealment is limited by setting the oversensing criterion used at box 214. For example, the oversensing criterion may need to be met only after Z consecutive R-wave sensing threshold exceedances are identified as evidence of oversensing, and X out of Y R-wave sensing threshold exceedances are identified as evidence of oversensing, preventing frequent disabling and re-enabling of post-atrial ventricular concealment, and requiring sufficient potential oversensing evidence to enable concealment. In this way, post-atrial ventricular concealment cannot be repeatedly and frequently enabled and disabled, for example, on alternating heartbeats. The Z consecutive R-wave sensing threshold violations identified as evidence of oversensing may be R-wave sensing threshold violations that occur during the Z consecutive post-atrial time intervals, for example, based on the event time signal generated by the oversensing event detector 180, in cases where R-wave sensing threshold violations, with or without interference, occur outside the post-atrial time interval and are associated with the R-wave sensing event signal.

[0092] Figure 8 This is a flowchart 300 of a method for accumulating evidence of oversensing and adjusting ventricular sensing control parameters based on the accumulated evidence, according to another example. At block 302, control circuitry 80 identifies, as described above... Figure 7 The described R-wave sensing threshold exceedance can be identified in response to an event time signal from the oversensing event detector 180. The time from the most recent previous atrial event (sensing or pacing) to the R-wave sensing threshold exceedance can be determined at box 304.

[0093] At box 305, control circuit 80 can determine the maximum peak amplitude of the ventricular signal after the R-wave sensing threshold exceeds the limit. (As mentioned above...) Figure 5As described, the peak amplitude can be determined by the oversensing event detector 180, and the amplitude signal 188 can be transmitted to the control circuit 80. In other instances, the control circuit 80 can receive a ventricular EGM signal 185 from the ventricular channel 89 and an event time signal 186 from the oversensing event detector 180. The control circuit 80 can determine the maximum peak amplitude of the ventricular EGM signal 185 after the event time signal 186 but within a post-atrial time interval. The peak time signal 187 can be transmitted to the control circuit 80 to mark the peak time of the event. In various instances disclosed herein, the control circuit 80 can use the time of R-wave sensing threshold exceedance or the time of peak amplitude as the event time, for example, to determine the time interval based on an atrial event at block 304. At other times, the control circuit 80 can identify an R-wave sensing threshold exceedance at block 302 based on the R-wave sensed event signal 178 received from the ventricular event detector 176, and determine the maximum peak amplitude of the ventricular EGM signal 185 after the R-wave sensed event signal.

[0094] If the determined time interval from the previous atrial event to the identified R-wave sensing threshold exceedance (or peak time) is not less than the oversensing event time interval threshold (the "None" branch of box 306), for example, within a post-atrial time interval, then no evidence of oversensing is detected. The peak amplitude determined at box 305 can be used to update the measure of R-wave amplitude at box 310. For example, the running average, median, minimum, or other measure of sensed R-wave amplitude can be determined using the peak amplitudes that were not detected as evidence of oversensing determined at box 305. The amount of R-wave amplitude can be determined based on the most recent 3, 6, 8, 12, 20, or other predetermined number of R-wave sensing threshold exceedances that were not detected as evidence of oversensing. After updating the amount of R-wave amplitude at box 310, control circuitry 80 returns to box 302 to wait for the next R-wave sensing threshold exceedance.

[0095] When evidence of oversensing is detected at box 308, such as based on the time of an R-wave sensing threshold exceedance (or peak time) from the most recent previous atrial event within the post-atrial time interval, control circuitry 80 may determine the oversensing event amplitude at box 311. The maximum peak amplitude after the R-wave sensing threshold exceedance determined at box 305 may be used to update the oversensing event amplitude at box 311. The oversensing event amplitude may be updated to be equal to the average, median, maximum, or other metric determined from the most recent predetermined number of R-wave sensing threshold exceedances detected as evidence of oversensing. For example, the highest maximum peak amplitude value among the most recent 3 to 12 peak amplitudes determined for an event identified as evidence of oversensing may be updated to the oversensing event amplitude at box 311. It should be noted that the oversensing event amplitude may be determined from a signal identified as evidence of oversensing, which may or may not be actually oversensed as a spurious R-wave or an event signal causing R-wave sensing, generated by ventricular event detector 176.

[0096] At box 312, control circuitry 80 determines whether at least Z consecutive R-wave sensing threshold violations are detected as evidence of oversensing. If not, control circuitry 80 may update the oversensing evidence counter to track oversensing evidence at box 312 and return to box 302. For example, the Z consecutive oversensing evidence counter may be reset to zero. The Y value of the X / Y counter may be incremented. If oversensing evidence is detected for the Z consecutive R-wave sensing threshold violations determined at box 312, control circuitry 80 determines whether the oversensing criterion is met at box 314. As mentioned above, it may be necessary for X out of the Y consecutive R-wave sensing threshold violations to be detected as evidence of oversensing. If not, control circuitry 80 may disable post-atrial ventricular concealment at box 318 (or concealment may remain disabled) and return to box 302.

[0097] When the oversensing criterion is met at block 314, control circuit 80 can analyze the oversensing event amplitude and / or R-wave amplitude metric at block 320. Based on this analysis, control circuit 80 can select to adjust ventricular sensing control parameters. For example, control circuit 80 can choose between enabling post-atrial ventricular blanking and adjusting ventricular sensitivity to reduce the likelihood of oversensing by ventricular event detector 176. To select adjusting ventricular sensitivity instead of enabling post-atrial ventricular blanking in response to meeting the oversensing criterion, it may be necessary for the R-wave amplitude to be greater than the oversensing event amplitude and / or greater than the current ventricular sensitivity setting by at least several times.

[0098] For example, at box 320, the R-wave amplitude can be compared to the oversensitivity event amplitude. The R-wave amplitude may need to be greater than the oversensitivity event amplitude by several predetermined percentages or fixed differences in order to select ventricular sensitivity adjustment rather than enabling post-atrial ventricular blanking. For example, the R-wave amplitude may need to be at least two or at least three times the oversensitivity event amplitude.

[0099] Alternatively, at box 322, the R-wave amplitude can be compared to the current ventricular sensitivity setting used to control the R-wave sensing threshold. The R-wave amplitude may need to be greater than at least a predetermined number, percentage, or fixed difference from the sensitivity setting, for example, greater than two or three times the current ventricular sensitivity setting, in order to select ventricular sensitivity adjustment instead of enabling atrial post-ventricular blanking.

[0100] When the R-wave amplitude does indeed meet an amplitude criterion relative to an oversensitivity amplitude measure and / or relative to the current ventricular sensitivity setting, control circuitry 80 can selectively adjust the ventricular sensitivity at block 324. In various instances, it may be necessary to meet one or both requirements represented by blocks 320 and 322 to select ventricular sensitivity adjustment at block 324. Ventricular sensitivity can be adjusted in predetermined increments, such as 0.1 mV, 0.2 mV, 0.25 mV, 0.3 mV, 0.5 mV, or other increments. In other instances, the ventricular sensitivity setting can be adjusted to be greater than the oversensitivity event amplitude setting by a predetermined amplitude difference, multiple, or percentage of the oversensitivity event amplitude. The ventricular sensitivity setting can be increased to a maximum value, which is a fraction or percentage of the R-wave amplitude, such as half or one-third of the R-wave amplitude.

[0101] When the R-wave amplitude is not sufficiently greater than the oversensitivity event amplitude and / or the ventricular sensitivity setting (the "No" branch of boxes 320 and / or 322), or when the ventricular sensitivity setting cannot be adjusted to a value sufficiently greater than the oversensitivity event amplitude and less than the R-wave amplitude, the control circuit 80 may choose to enable post-atrial ventricular blanking instead of adjusting the ventricular sensitivity setting. The control circuit 80 may enable post-atrial ventricular blanking at box 316.

[0102] In some cases, clinicians or users may be able to program medical devices to automatically enable and disable post-atrial ventricular concealment. However, clinicians or users may choose to "turn off" the automatic enabling and disabling of post-atrial ventricular concealment for some patients. For example, if post-ventricular concealment is enabled, patients with a history of tachyarrhythmias may be at risk of ventricular tachyarrhythmias. Therefore, users may choose to disable the automatic enabling and disabling of post-atrial ventricular concealment for some patients.

[0103] When the automatic adjustment for blanking is programmed to be "on," as defined in box 326, control circuitry 80 can automatically enable and disable post-atrial ventricular blanking in response to whether the oversensing criterion is met or not. When a clinician or other user programs the automatic adjustment for post-atrial ventricular blanking to be "off," post-atrial ventricular blanking is permanently disabled and cannot be automatically enabled by control circuitry 80 until the user programs the adjustment to be on.

[0104] If automatic blanking adjustment is programmed to be on when the oversensing criterion is met but the R-wave amplitude fails to meet the ventricular sensitivity adjustment criterion (the "Yes" branch of box 326), control circuit 80 can enable post-atrial ventricular blanking at box 316. The post-atrial ventricular blanking period can be set to a predetermined maximum blanking period or a maximum A-OS time interval determined based on the R-wave sensing threshold from an atrial event to evidence of oversensing. As described above, control circuit 80 can set the post-atrial ventricular blanking period after an atrial sensing event to a shorter time interval different from the post-atrial ventricular blanking period after an atrial pacing pulse. Each of these post-atrial sensing and post-atrial pacing ventricular blanking periods can be based on the time interval measured from the corresponding atrial sensing and atrial pacing event to an excess of the corresponding R-wave sensing threshold to evidence of oversensing.

[0105] When the automatic adjustment for post-atrial ventricular concealment is programmed to be off (No branch of box 326), control circuit 80 may maintain adjustment of the ventricular sensing control parameters in response to the satisfaction of oversensing criteria and the R-wave amplitude not meeting the criteria required for adjusting ventricular sensitivity. In this case, control circuit 80 may provide one or more other responses to the satisfaction of oversensing criteria. In some instances, control circuit 80 may generate a notification or report of oversensing evidence at box 328, for example, transmitted to, for example, […]. Figure 1 The notification or report can be stored in memory 82 until the next query session with the external device 50. In other instances, a notification or report can be transmitted to the external device 50 without delay to warn the patient or clinician that oversensitivity may occur and could interfere with appropriate treatment delivery.

[0106] Patients or clinicians can receive notifications or reports from external device 50. For example, a patient may receive an oversensitization notification and be instructed to seek medical advice or attention so that his / her clinician can review the evidence of oversensitization and reprogram ventricular sensing control parameters or other IMD control parameters as needed. In other instances, a clinician may receive reports of oversensitization evidence via external device 50 through a remote patient monitoring system and send programming instructions to external device 50 to reprogram IMD control parameters, which may include ventricular sensing control parameters, or at least enable automatic post-atrial ventricular blanking adjustment.

[0107] Additionally or alternatively, control circuitry 80 can adjust ventricular sensing control parameters by enabling post-atrial safety pacing at block 330 when oversensing criteria are met and the atrial blanking period after automatic activation is "off". In some instances, automatic activation of post-atrial safety pacing can be a programmable feature. For example, a clinician may be able to programmatically enable and disable post-atrial safety pacing by control circuitry 80. When post-atrial safety pacing is enabled, control circuitry 80 can enable a post-atrial safety pacing interval at block 330. The post-atrial safety pacing interval is a sensing window during which any R-wave sensed event signal generated by ventricular event detector 176 is largely an oversensed atrial event or an oversensed cardiac potential signal. Treatment delivery circuitry 84 can be configured to generate a ventricular safety pacing pulse in response to an R-wave sensed event signal received within the post-atrial safety pacing interval following an atrial sensing or pacing event. The ventricular safety pacing pulse can be generated and delivered when the post-atrial safety pacing interval expires. The post-atrial safe pacing interval can be the time interval at least covered by the ventricular physiological refractory period, such that if the R-wave sensing threshold exceedance during the post-atrial safe pacing interval is a true R wave, then ventricular safe pacing will fail to capture the ventricle due to the refractory nature of the His-Purkinje system and / or the ventricular myocardial tissue. If the R-wave sensing threshold exceedance during the post-atrial safe pacing interval is an atrial event erroneously sensed as an R wave, then ventricular safe pacing may capture and generate a ventricular beat because the cardiac tissue is not in a refractory state.

[0108] The post-atrial safe pacing interval can be set after an atrial sensing event (P-wave sensing event signal) and an atrial pacing pulse. After an atrial event (sensing or pacing), control circuitry 80 can initiate the safe pacing interval, which in some instances can be set to a shorter interval after an atrial sensing event following an atrial pacing pulse. In some instances, the safe pacing interval can be equal to the post-atrial time interval or the post-atrial ventricular blanking period. Additionally, control circuitry 80 can initiate an AV pacing interval (for delivering ventricular pacing pulses synchronized with the atria) in response to an atrial event. Treatment delivery circuitry 84 generates and delivers a ventricular pacing pulse when the safe pacing interval expires in response to an R-wave sensing event signal generated by ventricular event detector 176 during the safe pacing interval. When no R-wave sensing event signal is generated during the safe pacing interval, treatment delivery circuitry 84 maintains safe pacing and delivers the scheduled ventricular pacing pulse when the AV pacing interval expires. When an R-wave sensed event signal is generated by the ventricular event detector 176 after the safe pacing interval but before the AV pacing interval expires, the ventricular pacing pulse can be maintained at the AV pacing interval. During single-chamber ventricular pacing, the ventricular pacing pulse can be scheduled at a lower rate VV pacing interval instead of the AV pacing interval, and in the absence of an R-wave sensed event signal during the safe pacing interval and VV pacing interval, the ventricular pacing pulse is delivered upon the expiration of the lower rate VV pacing interval.

[0109] Because control circuit 80 is configured to suppress ventricular pacing pulses scheduled at AV or VV intervals in response to an R-wave sensed event signal, enabling a safe pacing interval after an atrial event prevents ventricular rhythm interruption when the R-wave sensed event signal is false. By adjusting the ventricular sensing control parameters by setting the safe pacing interval, control circuit 80 is allowed to identify potential oversensing events when post-atrial ventricular blanking is disabled, and to prevent ventricular rhythm interruption due to oversensing.

[0110] Although Figure 8 It is not explicitly stated that if post-ventricular safety pacing is enabled, it can be disabled at 316 when post-ventricular concealment is disabled. In response to receiving an oversensing evidence notification or report (box 328), the user or clinician can program automatic adjustments to post-ventricular concealment. The next time the oversensing criteria are met at box 314, and the R-wave amplitude does not meet the criteria required for adjusting the ventricular sensitivity setting, control circuitry 80 can enable post-ventricular concealment and disable post-ventricular safety pacing at box 316. In some instances, post-ventricular safety pacing can be disabled after only an atrial sensing event (P-wave sensing event signal), but regardless of whether concealment is enabled, post-ventricular safety pacing can remain enabled after an atrial pacing event because atrial pacing artifacts may be more likely to be oversensed by ventricular pathway 89 than atrial P waves.

[0111] Furthermore, it should be recognized that any adjustments to ventricular sensing control parameters made in response to meeting the oversensing criteria can be reversed when the oversensing criteria are no longer met. For example, when the oversensing criteria are not met at box 314 and post-atrial ventricular blanking is disabled at box 318, post-atrial safety pacing previously enabled at box 330 can be disabled in response to the failure to meet the oversensing criteria. At box 318, post-atrial safety pacing can be disabled in conjunction with disabling post-atrial ventricular blanking. Post-atrial safety pacing can be disabled at least after an atrial sensing event. When post-atrial blanking is disabled at box 318, post-atrial safety pacing can remain enabled after an atrial pacing pulse, at least in some instances, because oversensing of atrial pacing artifacts may occur when blanking is disabled.

[0112] When the ventricular sensitivity setting has been increased at box 324 in response to meeting the oversensitivity criteria and the R-wave amplitude measurement meeting the sensitivity adjustment criteria, the ventricular sensitivity setting can be reduced to a lower setting at box 318 in response to no longer meeting the oversensitivity criteria at box 314. In some cases, the ventricular sensitivity setting (in millivolts) can be reduced at box 318, except when post-atrial ventricular blanking is disabled. To reduce the ventricular sensitivity setting at box 318 in conjunction with disabling blanking, it may be necessary for the R-wave amplitude to be greater than a predetermined multiple of the reduced sensitivity setting and / or greater than a predetermined multiple of the oversensitivity event amplitude. In some instances, it may be necessary for the oversensitivity event amplitude to be less than the reduced sensitivity setting by at least a safety margin.

[0113] Criteria can be applied to the relative differences or ratios of the R-wave amplitude and the oversensitivity event amplitude, the R-wave amplitude measure and pending, the reduced ventricular sensitivity setting, and / or the oversensitivity event amplitude measure and pending, and then the ventricular sensitivity setting can be reduced before adjusting it to the reduced setting. For illustration, it can be verified that the R-wave amplitude is at least two to three times larger than the pending reduced sensitivity setting, and / or that the oversensitivity event amplitude may be smaller than the reduced sensitivity setting. If the criteria used to reduce the sensitivity setting are not met, the sensitivity setting can remain at the previously increased sensitivity setting even if the oversensitivity criterion is no longer met at box 314.

[0114] Figure 9This is a flowchart 400 of a method for controlling ventricular sensing control parameters based on evidence of oversensing in the presence of an atrial arrhythmia (AT), according to an example. Atrial arrhythmias, which may include different forms of rapid atrial rhythms (such as atrial flutter, atrial tachycardia, and atrial fibrillation), can be detected by control circuitry 80 at block 401 based on: analysis of a digital EGM signal generated by sensing circuitry 86 and passed to control circuitry 80, and / or analysis of the PP interval between consecutive P-wave sensed event signals, the RR interval between consecutive R-wave sensed event signals, the PP interval between consecutive P-wave sensed event signals, and the RP and / or PP interval between consecutive P-wave sensed event signals and R-wave sensed event signals. Control circuitry 80 can switch from an atrial-tracking ventricular pacing mode to a temporary non-tracking ventricular pacing mode (block 402) in response to the detection of an AT to facilitate a regular ventricular rate during ATs that do not track rapid atrial rates. In the absence of an R-wave sensed event signal, ventricular pacing pulses can be delivered at programmed lower ventricular rate intervals.

[0115] During AT, the amplitude of the atrial signal may be relatively low compared to the normal sinus P wave signal, making atrial event oversensing by the ventricular event detector 176 less likely to occur during AT compared to normal sinoatrial rhythm or pacing rhythm. However, in some cases, atrial event oversensing (or oversensing of cardiac potential signals) can still occur during AT, and because atrial depolarization occurs at a rapid and sometimes irregular rate depending on the type of AT, atrial events can be frequently and / or oversensed by the ventricular event detector 176 at irregular intervals, resulting in suppression of ventricular pacing pulses. If postventricular blanking is enabled when AT is detected, the blanking of the real R wave (which occurs at an irregular rate) may potentially lead to competitive ventricular pacing. In this case, even if intrinsic ventricular depolarization occurs during postventricular blanking, a ventricular pacing pulse can be delivered when the lower rate interval of VV expires. Therefore, techniques for accumulating evidence of oversensing during AT, especially when postventricular blanking is enabled, can be combined with Figure 7 and Figure 8 The described technical modifications can be used during normal sinus or pacing rhythms.

[0116] When post-atrial blanking is not enabled during the detected AT period (the "No" branch of box 404), control circuit 80 may continue to accumulate evidence of oversensing and, based on... Figure 7 or Figure 8The technology adjusts the ventricular sensing control parameters. When post-atrial ventricular blanking is disabled, the risk of competitive ventricular pacing is lower because the ventricular event detector 176 is not unaware of true R waves occurring early after an atrial event. Therefore, as long as blanking is disabled, specific monitoring for evidence of oversensing may not be necessary during AT. However, if post-ventricular blanking is detected as enabled at time AT, or due to... Figure 7 or Figure 8 If the technology is enabled at box 406 to meet the over-sensing criterion or to be enabled during continuous AT, then the control circuit 80 can be modified according to... Figure 9 The flowchart describes a technique for monitoring evidence of atrial event oversensing during AT (attack). Because atrial event oversensing can occur at rapid and / or irregular intervals during AT, it can occur at different times during ventricular circulation and even multiple times during ventricular circulation. Detecting evidence of oversensing during AT can be more challenging than during slower, sinus rhythms or paced rhythms. However, because competing ventricular pacing can occur when blanking is enabled, it is possible to perform… Figure 9 The technology is designed to detect evidence of oversensing and respond appropriately to minimize competitive ventricular pacing and the possibility of ventricular rhythms caused by oversensing.

[0117] If post-ventricular blanking is enabled (the "Yes" branch of box 404), then control circuitry 80 can determine in box 408 whether the ventricular rhythm is primarily a pacing rhythm at the programmed ventricular rate. When no R wave is sensed (or very few are sensed), the absence of an R wave sensing event signal is a patient-dependent indication of pacemaker instability. If no R wave sensing event signal or several R wave sensing event signals occur outside the post-atrial ventricular blanking period, then oversensing is unreliable. Therefore, as long as the primarily pacing ventricular rhythm persists, searching for sensing events that might indicate oversensing is unnecessary. If there is no evidence of R wave sensing, then the patient is receiving adequate ventricular rate support, and the likelihood of competitive ventricular pacing is low.

[0118] Primary ventricular pacing can be identified at box 408 based on a very small ratio of a predetermined number of consecutive pacing pulses or an event signal sensed by the R-wave to the delivered ventricular pacing pulses, such as 1:5, 1:6, 1:8, 1:10, 1:20, or even lower. The threshold used to detect primary ventricular pacing can be modulated based on pacing history. For example, if a patient is already highly dependent on the pacemaker, such as having a high percentage of ventricular pacing, then primary pacing is likely genuine, and therefore a lower primary pacing threshold can be used.

[0119] When primary pacing is detected at box 408, control circuitry 80 can determine whether primary pacing has lasted for a threshold time interval (or the number of pacing cycles). Sustained primary pacing can be detected when pacing is detected for at least one minute in a given instance. When sustained ventricular pacing is detected, control circuitry 80 can pause any further monitoring for evidence of oversensing at box 422, as long as AT is detected. Proper ventricular rate support is provided, and the risk of ventricular competing pacing is acceptablely low. Postventricular atrial silencing can be maintained. In some instances, control circuitry 80 can pause operations for collecting evidence of oversensing during a detected AT episode at box 422. Control circuitry 80 can return to box 401 and repeat the process of flowchart 400 the next time an AT episode is detected. In other instances, control circuitry 80 may temporarily pause at block 422 the operation used to collect evidence of oversensing for a predetermined time interval, such as one minute, two minutes, five minutes, or other time intervals, which may be incremented, and then return to block 407 to determine whether AT is still detected in post-atrial ventricular blanking enabled and in primary continuous ventricular pacing.

[0120] If no sustained ventricular pacing is detected, control circuitry 80 can wait at box 410 for primary ventricular pacing to become sustained (by returning to box 408). However, if control circuitry 80 no longer detects primary ventricular pacing at box 408 (and still detects AT episodes), control circuitry 80 can execute a modified oversensing monitoring technique that begins at box 412. At box 412, control circuitry 80 switches to test mode to monitor for evidence of oversensing. Test mode can be applied to at least one ventricular cycle. For example, when AT is detected, control circuitry 80 can switch to operate in a temporary non-atrial tracking pacing mode (box 402) and can enable post-atrial ventricular blanking (box 404). In response to the lack of detection of primary ventricular pacing in the temporary non-atrial tracking ventricular pacing mode, control circuitry 80 can be configured to switch from the temporary non-atrial tracking ventricular pacing mode to a test mode of atrial tracking ventricular pacing at box 412, where post-atrial ventricular blanking is disabled. In some instances, the pacing mode is switched to atrial tracking mode, where post-atrial ventricular blanking is disabled for only a single ventricular cycle, and then returns to a temporary non-atrial tracking ventricular pacing mode, where blanking is re-enabled. In other instances, control circuitry 80 can switch to a test mode of atrial tracking ventricular pacing mode, where post-atrial ventricular blanking is disabled for up to three or another limited number of ventricular cycles.

[0121] At block 414, control circuitry 80 updates an R-wave sensing event counter for each R-wave sensed event signal received from ventricular event detector 176 during atrial tracking pacing mode, where post-atrial ventricular blanking is disabled. One R-wave sensed event counter can be used to count the number of R-wave sensed event signals occurring within the post-atrial time interval of an atrial event. A second R-wave sensed event counter can be used to count the number of R-wave sensed event signals occurring after the post-atrial time interval. For example, an earlier sensed event counter can be incremented in response to an event time signal generated by the interaction between oversensing event detector 180 and an R-wave sensed event signal 178 generated by ventricular event detector 176. Different later sensed event counters can be incremented in response to an R-wave sensed event signal 178 generated by ventricular event detector 176 when no corresponding event time signal 186 is generated by oversensing event detector 180 (which may be disabled outside the post-atrial time interval). Each time the atrial-tracking ventricular pacing mode is activated, the R-wave sensing event counter is updated based on the timing of the R-wave sensing event signal relative to the atrial time interval.

[0122] At block 416, based on the counter values ​​updated at block 414, control circuitry 80 determines whether an R-wave sensed event during test mode occurs only during the post-atrial time interval or in the event of a ventricular pacing pulse (an event signal without R-wave sensing). If only ventricular pacing occurs during test pacing mode, both counter values ​​will be zero. If an R-wave sensed event signal occurs only during the post-atrial time interval, the corresponding early event counter will be non-zero, while the late event counter corresponding to an R-wave sensed event signal outside the post-atrial time interval will be zero. If only an early post-atrial event is sensed and / or ventricular pacing is delivered during test mode, control circuitry 80 switches back to a temporary non-atrial tracking ventricular pacing mode (from test pacing mode) at block 418 to re-enable post-ventricular blanking. Early events are evidence of potential oversensing, thus requiring post-atrial ventricular blanking.

[0123] Therefore, in response to determining that the R-wave sensed event signal generated during the test pacing mode is an early event occurring during the post-atrial time interval, the oversensing evidence counter can be incremented at box 418. At box 420, the oversensing evidence counter can be compared to a threshold. The oversensing threshold may require, for example, at least six instances of oversensing evidence detected in nine test pacing mode cycles (or X other criteria out of Y). When the oversensing evidence threshold is exceeded, the probability of oversensing during the detected AT is high. At box 422, test mode and oversensing evidence monitoring during the AT can be paused, thereby enabling post-atrial ventricular blanking. Test mode during the AT can be paused when the oversensing evidence counter reaches a threshold of at least 3, 5, 8, 12, or other predetermined number of test mode ventricular cycles determined as oversensing evidence, which may or may not be required to be continuous. Operations used to collect oversensing evidence during an AT episode, such as switching to a test mode for atrial tracking of ventricular pacing when atrial post-anesthesia is disabled and updating the R-wave sensing event counter, can be paused at box 422 for the remainder of the currently detected AT episode. Control circuitry 80 can return to box 401 to await the next AT episode detection. In other instances, control circuitry 80 can temporarily pause the test mode at box 422 for a predetermined time interval and then return to box 407 to proceed as needed while AT is still detected. Figure 9 The modified technology recovers accumulated evidence of oversensing.

[0124] When the oversensitivity evidence counter at box 420 is not greater than the threshold, control circuit 80 can return to box 407. As long as AT is still detected, ventricular blanking remains enabled, and ventricular pacing is not dominant during the temporary non-atrial tracking pacing mode, control circuit 80 can continue to accumulate oversensitivity evidence by briefly switching to test mode at box 412. The early R-wave sensing event counter and the late R-wave sensing event counter can maintain their respective current values ​​and continue to increment based on the timing of the R-wave sensing event signal during test mode. The R-wave sensing event counter can be cleared (reset to zero) when control circuit 80 pauses switching to test mode at box 422 or when AT is no longer detected.

[0125] If the late event counter corresponding to an R wave sensed outside the post-atrial time interval is non-zero, and the early sensing event counter corresponding to an R wave sensed during the post-atrial time interval is zero, then control circuit 80 determines at block 430 a "late" R wave that did not occur during the post-atrial time interval. In this case, control circuit 80 can decrement the oversensing evidence counter at block 432. When blanking is disabled, no R wave is sensed during the post-atrial time interval, therefore there is no evidence of possible oversensing.

[0126] If the oversensing evidence counter value at box 434 becomes less than the "no oversensing" threshold, for example, less than 2 after a predetermined number (e.g., 12) of test mode ventricular cycles, then control circuitry 80 can disable post-atrial ventricular silencing at box 436. Switching to test mode can also pause at box 436 because post-atrial silencing is no longer enabled. Oversensing evidence monitoring can be terminated until no more AT events are detected. In some instances, when combined with... Figure 7 or Figure 8 When the described technique is disabled after atrial silencing, monitoring for evidence of oversensing can continue during AT episodes (in box 406).

[0127] When the oversensitivity evidence counter value at box 434 is not less than the "oversensitivity" threshold, control circuit 80 continues to intermittently switch to test mode at box 412 (the "none" branch of box 434). Control circuit 80 may switch to test pacing mode every five cycles, every ten cycles, or other selected frequencies for one ventricular cycle to continue accumulating oversensitivity evidence (or lack thereof).

[0128] In some cases, a mixture of early and late R-wave sensing events may exist during test mode. When both the early and late R-wave sensing event counters have non-zero values, control circuitry 80 advances from box 430 (“None” branch) to box 435. The mixture of early and late R-wave sensing events can indicate evidence of oversensing of rapid and / or irregular atrial rates. In response to the detection of a combination of early (during the post-atrial time interval) and late (after the post-atrial time interval) R-wave sensing events, the oversensing evidence counter can be incremented at box 435.

[0129] Control circuit 80 can determine at block 439 whether the oversensing evidence meets the oversensing evidence criterion in response to the addition of oversensing evidence at block 435. The oversensing evidence criterion applied to the accumulated oversensing evidence during the process of flowchart 400, or any other flowchart presented herein, may include a fixed or adjustable threshold. The adjustable oversensing evidence threshold may be set based on the ratio of the atrial post-atrial time interval to the atrial event interval. The atrial event interval may be a PP interval determined between event signals sensed by a series of P waves generated by the atrial channel of sensing circuit 86. In other cases, the atrial event interval may begin and / or end with an atrial pacing pulse. In the case of flowchart 400, at block 439, control circuit 80 can determine the atrial event interval of the detected AT interval from the PP interval. During the AT, R waves may occur randomly at any point during the AT interval, resulting in a mixture of early R wave sensing events and late R wave sensing events (the "none" branch of block 430). If the post-atrial time interval is, for example, one-third of the total AT interval, then the expected actual R wave occurs for one-third of the time during the post-atrial time interval and two-thirds of the time after the post-atrial time interval. Therefore, control circuitry 80 can set an oversensing evidence threshold at block 439 as the ratio of the post-atrial time interval to the detected AT interval, for example, one-third in the illustrative example. If more than one-third of the R-wave sensed event signals are early, then at least some of these early R-wave sensed event signals during the post-atrial time interval can be evidence of oversensing. Therefore, the ratio of the early event counter value to the late event counter value can be compared to the oversensing evidence threshold at block 439, which is set (and can be variable) based on the ratio of the post-atrial time interval to the AT interval. The oversensing evidence threshold ratio applied at block 439 can be adjusted when the AT interval changes during or between detected AT episodes.

[0130] When the oversensing threshold ratio is not exceeded at box 439, control circuit 80 can return to box 412 to repeat the pacing mode test for monitoring additional ventricular circulation oversensing during detected AT episodes. Although Figure 9 Although not explicitly shown, it should be understood that when no more AT events are detected, the control circuit 80 can pause the test mode and return to block 401 to wait for the next AT event detection.

[0131] When the oversensing evidence threshold ratio (or another fixed oversensing evidence threshold) is exceeded at box 439, control circuit 80 may attempt to adjust ventricular sensitivity at box 438 to reduce or eliminate the risk of oversensing. At box 437, control circuit 80 may determine whether an R-wave amplitude criterion is met. Control circuit 80 may compare the amplitude measure of an early event sensed during the post-atrial time interval with the amplitude measure of a late event sensed outside the post-atrial time interval or a previously stored R-wave amplitude. (As described above...) Figure 8 If the R-wave amplitude is at least a predetermined multiple, such as at least twice, of the programmed ventricular sensitivity setting, then control circuitry 80 can increase the ventricular sensitivity setting at block 438 to reduce the likelihood of oversensing. In some instances, the R-wave amplitude may need to be greater than a predetermined multiple of the oversensing event amplitude determined from early events and / or greater than a predetermined multiple of the ventricular sensitivity setting. Control circuitry 80 can increase the ventricular sensitivity setting at block 438 and return to block 412. When the R-wave amplitude criterion is not met at block 437, control circuitry 80 can return to block 412, without adjusting the ventricular sensitivity, and instead continue switching to test mode at a predetermined frequency to accumulate oversensing evidence, adjusting the ventricular sensing control parameters as needed until no more AT is detected or the oversensing evidence counter is less than the "no oversensing" threshold (block 434), or greater than the oversensing threshold at block 420, and suspend the test (blocks 436 or 422, respectively).

[0132] The technique in flowchart 400 can be utilized during a detected AT episode to accumulate evidence of oversensing when atrial rates are rapid and / or irregular. When AT is no longer detected, control circuit 80 can... Figure 7 or Figure 8 The technology switches back to accumulating evidence of oversensing. Using the techniques disclosed herein, medical devices can detect and accumulate evidence of oversensing even when events are not actually oversensed or when such oversensing events are ignored and do not interfere with ventricular pacing control.

[0133] These technologies improve the reliability of ventricular sensing and pacing performance in medical devices performing these technologies, particularly when one or two ventricular sensing electrodes are positioned adjacent to or even within the atrium and ventricle. This is especially important when ventricular pacing is delivered to devices such as... Figures 1 to 3This situation may occur with the His-Purkinje system described herein. The accumulation of evidence of oversensing, including actual or potential oversensing of atrial events and / or cardiac potential signals, can be used in devices having or coupled to ventricular sensing electrodes that are adjacent to or located in the atria or ventricles. When ventricular pacing leads or electrodes are positioned in or relatively low along the ventricles, for example, for pacing the ventricular myocardium at the ventricular apex, one or two ventricular sensing electrodes are relatively far from the atrial chambers and the His bundle and bundle branches, making oversensing of atrial events and cardiac potential signals unlikely or improbable. Subsequently, in such systems, interference with ventricular pacing control by oversensing atrial events or oversensing cardiac potential signals is unlikely. Nevertheless, the techniques disclosed herein can be implemented in any medical device configured for ventricular sensing, such as controlling ventricular pacing and detecting and delivering ventricular arrhythmia therapy, when oversensing might interfere with proper device operation.

[0134] The following includes examples of techniques based on aspects of this disclosure.

[0135] Clause 1: A method comprising: sensing a ventricular electrical signal; setting an R-wave sensing threshold; receiving an atrial event signal; setting an after-atrial time interval in response to receiving the atrial event signal; generating an event time signal in response to the ventricular electrical signal being equal to or greater than the R-wave sensing threshold during the after-atrial time interval; determining a count of the event time signal in response to the generated event time signal; and adjusting ventricular sensing control parameters based on the count of the event time signal.

[0136] Clause 2: The method described in Clause 1 includes: adjusting the ventricular sensing control parameters by enabling the post-atrial ventricular blanking period.

[0137] Clause 3: The method according to Clause 2 includes: in response to receiving a next atrial event signal, setting the post-atrial time interval and the post-atrial ventricular blanking period, the post-atrial time interval and the post-atrial ventricular blanking period at least partially overlapping; generating a next event time signal without generating an R-wave sensing event signal in response to the ventricular electrical signal being equal to or greater than the R-wave sensing threshold during the overlapping portion of the post-atrial ventricular blanking period and the post-atrial time interval; and increasing the count of the event time interval in response to the next event time signal.

[0138] Clause 4: The method according to any one of Clauses 1 to 3 further includes: determining a time interval from the atrial event signal to the event time signal; and adjusting the ventricular sensing control parameters by adjusting the end time of the post-atrial ventricular silencing period based on the determined time interval.

[0139] Clause 5: The method according to any one of Clauses 1 to 4, wherein adjusting the ventricular sensing control parameters includes adjusting the ventricular sensitivity setting used to set the R-wave sensing threshold.

[0140] Clause 6: The method according to Clause 5 includes: determining at least one amplitude amount from the ventricular electrical signal; and adjusting the ventricular sensitivity setting based on the at least one amplitude amount.

[0141] Clause 7: The method according to Clause 6 includes: generating an R-wave sensing event signal in response to the ventricular electrical signal exceeding the R-wave sensing threshold; determining a peak amplitude associated with the R-wave sensing event signal from the ventricular electrical signal; determining the at least one amplitude amount based at least on the peak amplitude; and adjusting a ventricular sensitivity setting based on the R-wave amplitude amount.

[0142] Clause 8: The method according to Clause 7 includes: determining an oversensitized event amplitude associated with the event time signal from the ventricular electrical signal; determining the at least one amplitude amount by determining an oversensitized event amplitude amount based at least on the oversensitized event amplitude; and adjusting the ventricular sensitivity setting based on a comparison of the R-wave amplitude amount with at least one of the oversensitized event amplitude and the ventricular sensitivity setting.

[0143] Clause 9: The method according to any one of Clauses 1 to 8 includes: adjusting the count of the event time signal in response to no event time signal received from the sensing circuit during the next post-atrial time interval; and adjusting the ventricular sensing control parameters by disabling the post-atrial ventricular blanking period based on the adjusted count of the event time interval.

[0144] Clause 10: The method according to any one of Clauses 1 to 9 further comprises: generating an R-wave sensing event signal in response to the ventricular electrical signal exceeding the R-wave sensing threshold; sensing an atrial electrical signal; detecting an atrial arrhythmia from the atrial electrical signal; determining that the R-wave sensing event signal was generated by the sensing circuit during a post-atrial time interval; increasing the count of oversensing evidence in response to the generation of the R-wave sensing event signal during the post-atrial time interval; and enabling a post-atrial ventricular blanking period in response to the increased count of oversensing evidence.

[0145] Clause 11: The method according to Clause 10, wherein the control circuit is further configured to: determine an atrial event interval between two consecutive atrial event signals; set an oversensing evidence criterion based on the ratio of the post-atrial time interval to the atrial event interval; compare the count of oversensing evidence with the oversensing criterion; and enable a post-atrial ventricular blanking period in response to an increased oversensing evidence count satisfying the oversensing evidence criterion.

[0146] Clause 12: The method according to any one of Clauses 1 to 11 further comprises: generating an R-wave sensing event signal in response to the ventricular electrical signal exceeding the R-wave sensing threshold; sensing an atrial electrical signal; detecting an atrial arrhythmia from the atrial electrical signal; temporarily disabling a post-atrial ventricular blanking period in response to the detection of the atrial arrhythmia; determining that the R-wave sensing event signal is generated by the sensing circuit outside the post-atrial time interval when the post-atrial ventricular blanking period is temporarily disabled; and disabling the post-atrial ventricular blanking period during the detected atrial rapid arrhythmia in response to generating at least the R-wave sensing event signal outside the post-atrial time interval when the post-atrial ventricular blanking period is disabled.

[0147] Clause 13: The method according to any one of Clauses 1 to 12 includes: generating an atrial pacing pulse; sensing an atrial electrical signal; generating a P-wave sensing event signal in response to the atrial electrical signal exceeding a P-wave sensing threshold; receiving the atrial event signal associated with one of the atrial pacing pulse or the P-wave sensing event signal; setting the atrial post-atrial time interval to a first duration in response to receiving the atrial event signal associated with the P-wave sensing event signal; and setting the atrial post-atrial time interval to a second duration greater than the first duration in response to receiving the atrial event signal associated with the atrial pacing pulse.

[0148] Clause 14: The method according to any one of Clauses 1 to 13 includes: adjusting the ventricular sensing control parameters by setting a safe pacing interval in response to the atrial event signal; generating an R-wave sensing event signal during the safe pacing interval in response to the ventricular electrical signal exceeding the R-wave sensing threshold during the safe pacing interval; and generating a ventricular pacing pulse when the safe pacing interval expires in response to the generation of the R-wave sensing event signal during the safe pacing interval.

[0149] Clause 15: The method according to any one of Clauses 1 to 14 further comprises: setting a post-atrial ventricular blanking period in response to the atrial event signal; and generating an R-wave sensing event signal in response to an external exceedance of the R-wave sensing threshold by the ventricular electrical signal during the post-atrial time interval and the post-atrial ventricular blanking period.

[0150] Clause 16: The method according to any one of Clauses 1 to 15 includes: comparing the count of an event time signal with a first oversensing criterion when the post-atrial ventricular silencing period is enabled; comparing the count of the event time signal with a second oversensing criterion different from the first oversensing criterion when the post-atrial ventricular silencing period is disabled; and adjusting ventricular sensing control parameters in response to the count of an event time signal that satisfies either the first or the second oversensing criterion.

[0151] Clause 17: A non-transitory computer-readable storage medium comprising a set of instructions that, when executed by control circuitry of a medical device, cause the medical device to: sense a ventricular electrical signal; set an R-wave sensing threshold; receive an atrial event signal; set a post-atrial time interval in response to receiving the atrial event signal; generate an event time signal in response to the ventricular electrical signal being equal to or greater than the R-wave sensing threshold during the post-atrial time interval; determine a count of the event time signal in response to the generated event time signal; and adjust ventricular sensing control parameters based on the count of the event time signal.

[0152] It should be understood that, depending on the instance, certain actions or events of any method described herein may be performed in a different order, and may be added, combined, or omitted entirely (e.g., performing the method may not require all the described actions or events). Furthermore, in some instances, actions or events may be performed simultaneously, for example, through multithreading, interrupt handling, or multiple processors, rather than sequentially. Additionally, although some aspects of this disclosure are described for clarity as being performed by a single circuit or unit, it should be understood that the techniques of this disclosure can be performed by a combination of circuits or components associated with, for example, a medical device.

[0153] In one or more instances, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functionality may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. Computer-readable media may include non-transitory computer-readable media, which correspond to tangible media such as data storage media (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 is accessible by a computer).

[0154] The instructions can 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 arrays (FPGAs), or other equivalent integrated or discrete logic circuits. Therefore, the term "processor" as used herein can refer to any of the foregoing structures or any other structures suitable for implementing the techniques described herein. Furthermore, this technique can be fully implemented in one or more circuit or logic elements.

[0155] Therefore, the medical device has been presented in the foregoing description with reference to specific examples. It should be understood that the various aspects disclosed herein can be combined in combinations different from the specific combinations presented in the accompanying drawings. It should be understood that various modifications can be made to the reference examples without departing from the scope of this disclosure and the following claims.

Claims

1. A medical device comprising: The sensing circuit is configured to: Sense ventricular electrical signals; Set the R-wave sensing threshold; Receive atrial event signals; The atrial post-atrial time interval is set in response to the atrial event signal; as well as An event time signal is generated in response to the ventricular electrical signal being equal to or greater than the R-wave sensing threshold during the post-atrial time interval. as well as Control circuit, the control circuit being configured to: Determine the count of the event time signals generated by the sensing circuit; and The ventricular sensing control parameters are adjusted based on the counts of the event time signal.

2. The medical device according to claim 1, wherein: The control circuit is configured to adjust the ventricular sensing control parameters by activating the post-atrial ventricular blanking period.

3. The medical device according to claim 2, wherein: The sensing circuit is configured to: In response to receiving the next atrial event signal, the post-atrial time interval and the post-atrial ventricular blanking period are set, wherein the post-atrial time interval and the post-atrial ventricular blanking period at least partially overlap. In response to the ventricular electrical signal being equal to or greater than the R-wave sensing threshold during the overlap of the post-atrial ventricular silencing period and the post-atrial time interval, a next event time signal is generated instead of an R-wave sensing event signal. as well as The control circuit is configured to increase the count of the event time interval in response to the next event time signal.

4. The medical device according to any one of claims 1 to 3, wherein the control circuit is configured to: Determine the time interval from the atrial event signal to the event time signal; The ventricular sensing control parameters are adjusted by adjusting the end time of the post-atrial ventricular silencing period based on the determined time interval.

5. The medical device according to any one of claims 1 to 3, wherein the control circuit is configured to adjust the ventricular sensing control parameters by adjusting the ventricular sensitivity setting used to set the R-wave sensing threshold.

6. The medical device according to claim 5, wherein the control circuit is configured to: Determine at least one amplitude quantity from the ventricular electrical signal; and The ventricular sensitivity setting is adjusted based on the at least one amplitude value.

7. The medical device according to claim 6, wherein: The sensing circuit is configured to: An R-wave sensing event signal is generated in response to the ventricular electrical signal exceeding the R-wave sensing threshold. The peak amplitude associated with the event signal sensed by the R wave is determined from the ventricular electrical signal; The control circuit is configured to: The R-wave amplitude is determined at least based on the peak amplitude as the at least one amplitude; and The ventricular sensitivity setting is adjusted based on the R-wave amplitude.

8. The medical device according to claim 7, wherein: The sensing circuit is configured to determine the amplitude of an oversensing event associated with the event time signal from the ventricular electrical signal; The control circuit is configured to: The amplitude of the oversensing event is determined at least based on the amplitude of the oversensing event, and the at least one amplitude is determined; as well as The ventricular sensitivity setting is adjusted based on a comparison of the R-wave amplitude with at least one of the oversensitivity event amplitude and the ventricular sensitivity setting.

9. The medical device according to any one of claims 1 to 3, wherein the control circuit is configured to: In response to the absence of an event time signal from the sensing circuit during the next atrial post-interval, the count of the event time signal is adjusted; The ventricular sensing control parameters are adjusted by disabling the post-atrial ventricular silencing period based on the adjusted count of the event time signal.

10. The medical device according to any one of claims 1 to 3, wherein: The sensing circuit is configured to: An R-wave sensing event signal is generated in response to the ventricular electrical signal exceeding the R-wave sensing threshold; and Sensing atrial electrical signals; The control circuit is configured to: Detecting atrial arrhythmias from the aforementioned atrial electrical signals; The event signal of the R wave sensing is generated by the sensing circuit during the post-atrial time interval; The count of oversensing evidence is increased in response to the generation of the R-wave sensing event signal during the post-atrial time interval; and The post-atrial ventricular silencing period is activated in response to an increased count of oversensitivity evidence.

11. The medical device of claim 10, wherein the control circuit is configured to: Determine the atrial event interval between two consecutive atrial event signals; The oversensing evidence standard is set based on the ratio of the post-atrial time interval to the atrial event interval; Compare the count of oversensitized evidence with the oversensitization standard; as well as In response to the increased count of oversensitivity evidence that meets the oversensitivity evidence criteria, the post-atrial ventricular silencing period is enabled.

12. The medical device according to any one of claims 1 to 3, wherein: The sensing circuit is configured to: An R-wave sensing event signal is generated in response to the ventricular electrical signal exceeding the R-wave sensing threshold; and Sensing atrial electrical signals; The control circuit is configured to: Detecting atrial arrhythmias from the aforementioned atrial electrical signals; In response to the detection of the atrial arrhythmia, the post-atrial ventricular blanking period is temporarily disabled; Determine that when the post-atrial ventricular blanking period is temporarily disabled, the sensing circuit generates an R-wave sensing event signal outside the post-atrial time interval; and In response to generating at least the R-wave sensed event signal outside the post-atrial time interval when the post-atrial ventricular blanking period is disabled, the post-atrial ventricular blanking period is disabled during the detected atrial arrhythmia.

13. The medical device according to any one of claims 1 to 3, further comprising: Therapeutic delivery circuitry is configured to generate atrial pacing pulses; The sensing circuit is configured to: Sensing atrial electrical signals; as well as A P-wave sensing event signal is generated in response to the atrial electrical signal exceeding the P-wave sensing threshold. Receive the atrial event signal associated with either an atrial pacing pulse generated by the treatment delivery circuit or an event signal sensed by a P wave generated by the sensing circuit; In response to receiving the atrial event signal associated with the P-wave sensed event signal, the post-atrial time interval is set to a first duration; as well as In response to receiving the atrial event signal associated with an atrial pacing pulse, the post-atrial time interval is set to a second duration greater than the first duration.

14. The medical device according to any one of claims 1 to 3, wherein: The control circuit is configured to adjust the ventricular sensing control parameters by setting a safe pacing interval in response to receiving an atrial event signal; The sensing circuit is configured to generate an R-wave sensing event signal during the safe pacing interval in response to a ventricular electrical signal that exceeds the R-wave sensing threshold during the safe pacing interval. The medical device further includes a treatment delivery circuit configured to generate a ventricular pacing pulse when the safe pacing interval expires, in response to generating an R-wave sensed event signal during the safe pacing interval.

15. The medical device according to any one of claims 1 to 3, wherein the sensing circuit is configured to: In response to the atrial event signal, a post-atrial ventricular silencing period is set; and In response to the ventricular electrical signal exceeding the R-wave sensing threshold during the post-atrial time interval and the post-atrial ventricular concealment period, an R-wave sensing event signal is generated.

16. The apparatus according to any one of claims 1 to 3, wherein the control circuit is further configured to: When the post-atrial ventricular silencing period is enabled, the count of the event time signal is compared with the first oversensing criterion; When the post-atrial ventricular silencing period is disabled, the count of the event time signal is compared with a second oversensing criterion, which is different from the first oversensing criterion; and The ventricular sensing control parameters are adjusted in response to the count of an event time signal that satisfies either the first oversensing criterion or the second oversensing criterion.

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