Selective anodal and cathodal stimulation

Abstract

A medical device system includes a medical device configured to deliver ventricular pacing to a heart of a patient. The medical device system also includes processing circuitry configured to receive electrocardiogram data of the patient sensed by the medical device during delivery of the ventricular pacing. The processing circuitry is further configured to identify one or more heartbeats within the electrocardiogram data. The processing circuitry is further configured to determine one or more patient parameters based on the one or more heartbeats. The processing circuitry is further configured to control the medical device to deliver cathodic pacing or anodal-cathodic pacing based on the one or more patient parameters.

Description

Technical Field

[0001] This disclosure relates in general to medical device systems.

[0002] Cross-reference to related applications

[0003] This application claims priority to U.S. Provisional Patent Application No. 63 / 602,092, filed November 22, 2023, the entire contents of which are incorporated herein by reference. Background Technology

[0004] Medical devices can be used to monitor a patient's physiological signals. For example, some medical devices are configured to sense electrocardiogram (EGM) signals, which indicate the heart's electrical activity via electrodes. Some medical devices can be configured to deliver treatment in conjunction with or independently of monitoring physiological signals. For example, cardiac pacing is an effective treatment for patients with bradycardia due to sinoatrial node dysfunction or atrioventricular block. However, conventional right ventricular apical pacing (RVAP) can cause electrical and mechanical asynchrony. Summary of the Invention

[0005] Conduction system pacing (such as left bundle branch area pacing (LBBAP) therapy) is a physiological pacing method that activates normal cardiac conduction pathways and provides synchronized ventricular contractions. Conduction system pacing may involve placing electrodes (e.g., distal tip electrodes) of pacing leads in or near the heart's electrical conduction system to restore normal electrical conduction and improve cardiac function.

[0006] Medical devices such as pacemakers or implantable cardioverter defibrillators (ICDs) can send electrical signals to the heart. The device can deliver pacing via a cathode electrode located in the target cardiac tissue (e.g., in a lead located in the cardiac tissue (e.g., LBB) or on the distal tip of the device) and an anode electrode located outside the heart (such as the device's metal casing, sometimes called a "canister") . When the device sends an electrical signal, the signal travels from the cathode in the heart through the myocardium and then back to the anode electrode on the device casing.

[0007] In some examples, medical devices may use two electrodes (e.g., two relatively closely spaced electrodes on a lead or pacemaker) to capture tissue in the heart. When the device sends an electrical signal, the signal travels from the cathode electrode (e.g., a more distal electrode on the lead) in the target heart tissue through the myocardium and then back to the anode electrode (e.g., a sub-distal electrode on the lead). With this configuration, the cathode electrode at the heart tissue typically captures the heart tissue and does not capture any tissue that is near or in contact with the anode electrode. However, for certain patients or certain arrhythmic states within a patient, capturing tissue via the anode electrode may be beneficial.

[0008] Therefore, according to the technology of this disclosure, a medical device can be configured to switch between cathode-only stimulation (e.g., capture only via a cathode electrode) and anodic-cathode (AC) stimulation (e.g., capture via both cathode and anode electrodes) based on measured patient parameters. For example, if the patient has normal atrioventricular conduction, the medical device can deliver cathode-only LBBAP or left ventricular stimulation and fuse the pacing activation with the native activation of the right ventricle. However, if the patient has prolonged atrioventricular conduction (e.g., conduction time greater than 200 ms), the patient may no longer have the appropriate timing for the native activation of the right ventricle. Therefore, the medical device can advantageously switch to delivering AC stimulation to activate both ventricles of the heart. Anode stimulation can activate the right ventricle, while cathode stimulation activates the left ventricle, thereby correcting for the long atrioventricular delay while providing interventricular and intraventricular synchrony. In this way, the medical device can deliver more effective treatment to treat the patient, thereby improving health outcomes.

[0009] In some examples, a medical device system includes a medical device configured to deliver ventricular pacing to a patient's heart; and processing circuitry configured to: receive electrocardiogram (ECG) data of the patient sensed by the medical device during the delivery of ventricular pacing; identify one or more heartbeats within the ECG data; determine one or more patient parameters based on the one or more heartbeats; and control the medical device to deliver cathodic pacing or anodic-cathode pacing based on the one or more patient parameters.

[0010] In some examples, a medical device includes a cathode electrode configured to deliver ventricular pacing to a patient's heart; an anode electrode configured to deliver ventricular pacing to the heart; and processing circuitry configured to: receive electrocardiogram (ECG) data of the patient sensed by the medical device during ventricular pacing delivery; identify one or more heartbeats within the ECG data; determine one or more patient parameters based on the one or more heartbeats; and control the medical device to deliver cathode pacing or anode-cathode pacing based on the one or more patient parameters.

[0011] In some examples, one approach includes receiving electrocardiogram (ECG) data of a patient sensed by a medical device during delivery of ventricular pacing by processing circuitry; identifying one or more heartbeats within the ECG data by processing circuitry; determining one or more patient parameters based on the one or more heartbeats by processing circuitry; and controlling the medical device to deliver cathodic pacing or anodic-cathode pacing based on the one or more patient parameters by processing circuitry.

[0012] This disclosure is intended to provide an overview of the subject matter described herein. The present invention is not intended to provide an exclusive or exhaustive explanation of the systems, apparatus, and methods described in detail in the following drawings and specification. Further details of one or more examples of the present disclosure are set forth in the following drawings and specification. Other features, objectives, and advantages will be apparent from the specification, drawings, and claims. Attached Figure Description

[0013] Figure 1 The example healthcare system environment was illustrated with patient examples.

[0014] Figure 2 This is a functional block diagram illustrating an example configuration of an implantable medical device (IMD).

[0015] Figure 3 This is a functional block diagram illustrating an example configuration of an external device.

[0016] Figure 4 This is a block diagram illustrating an example system that includes an access point, a network, external computing devices such as servers, and one or more other computing devices that can be connected to the IMD and external devices.

[0017] Figure 5 This is a flowchart of an example method for operating a medical device to transition from pacing in the left cathodic bundle branch region to pacing in the anodic-cathonic left bundle branch region and intermittent pacing, based on the technology of this disclosure.

[0018] Throughout the specification and drawings, similar reference characters represent similar elements. Detailed Implementation

[0019] Conduction system pacing (CSP), also known as physiological pacing, is a medical procedure and technique used to regulate heartbeats when the heart's natural electrical conduction system malfunctions. The heart relies on a specialized conduction system to generate and transmit electrical signals that coordinate the contractions of its chambers, ensuring efficient blood pumping. When there is an abnormality or disorder in the heart's conduction system, it can lead to irregular heart rhythms (e.g., arrhythmias) or abnormal heart rates. In such cases, medical devices such as pacemakers are used to restore and maintain a normal heart rate and rhythm.

[0020] Left bundle branch area pacing (LBBAP) is a form of cardiac pacing (CSP) and a specialized cardiac pacing technique used in patients with certain cardiac conduction disorders. LBBAP involves placing the cathode electrode (e.g., distal tip electrode) of a pacing lead or device in or near the left bundle branch of the heart's electrical conduction system to restore normal electrical stimulation of the ventricles and improve cardiac function. The left bundle branch (LBB) is a critical part of the heart's conduction system responsible for transmitting electrical signals to the ventricles, the lower chambers of the heart. When there is a block or delay in the LBB, the coordination and timing of ventricular contractions can be impaired, resulting in inefficient blood pumping. In left bundle branch pacing (LBBP), the lead delivers electrical pulses to the LBB, bypassing conduction block or delay. By directly (e.g., LBBP) or indirectly (e.g., LBBAP) stimulating the left bundle branch, LBBP or LBBAP (respectively) can restore synchronous activation of the ventricles, thereby improving their pumping efficiency.

[0021] Both cathodic pacing and AC pacing are methods used to deliver electrical pulses to cardiac tissue during cardiac pacing. Cathodic pacing (which is likely more common than AC pacing) uses a cathode electrode (e.g., on a lead) to deliver electrical pulses to the heart, while the anode electrode (e.g., the housing of a medical device) acts as a ground or reference point. The circuitry is accomplished by current flowing from the cathode electrode to the cardiac tissue and then to the anode electrode.

[0022] In some examples, the medical device can use cathode and anode electrodes positioned close to each other within the heart to capture tissue in the heart (e.g., both the anode and cathode electrodes are positioned on a lead). When the device sends an electrical signal, the signal travels from the cathode electrode (e.g., a more distal electrode on the lead) in the target heart tissue through the myocardium and then back to the anode electrode (e.g., a sub-distal electrode on the lead).

[0023] Using this configuration, the cathode electrode at the heart tissue typically captures heart tissue and does not capture any tissue near or in contact with the anode electrode. However, for some patients or certain arrhythmia conditions, capturing tissue via the anode electrode may be beneficial. Therefore, according to the technology of this disclosure, a medical device can be configured to switch between cathode-only pacing (“cathode pacing”) and anode-cathode (AC) stimulation based on measured patient parameters. For example, if the patient has normal atrioventricular conduction, the medical device can deliver cathode pacing and fuse the activation of pacing with the native activation of the right ventricle. However, if the patient experiences prolonged atrioventricular conduction (e.g., conduction time (and / or atrioventricular (AV) delay) greater than 200 milliseconds), the medical device can advantageously switch to delivering AC stimulation to activate both ventricles of the heart. Anode stimulation can activate the right ventricle, while cathode stimulation activates the left ventricle, thereby correcting for the long atrioventricular delay while providing interventricular and intraventricular synchronization.

[0024] Figure 1 This is a conceptual diagram of a medical device system 2 capable of pacing and sensing in a patient's heart 8. The medical device system 2 may include an implantable medical device (IMD) 10 and an external device 12. The IMD 10 can be connected to the external device 12 and... Figure 1 At least one of the other devices not shown communicates wirelessly. The IMD 10 can be implanted in a patient and coupled to one or more implantable medical leads. The IMD 10 can be configured to sense one or more electrocardiograms (EGMs) via multiple electrodes and deliver conduction system pacing, such as LBBAP.

[0025] External device 12 may be a computing device having a user-viewable display and an interface (i.e., a user input mechanism) for providing input to external device 12. In some examples, external device 12 may be a laptop, tablet, workstation, one or more servers, cellular phone, personal digital assistant, or another computing device running an application that enables the computing device to interact with IMD 10. In some examples, external device 12 may be implemented as multiple computing systems configured to receive cardiac electrical signals, which may include at least one EGM signal input received directly or indirectly from IMD 10. In some examples, external device 12 is a computing device included in a remote patient monitoring system, such as CARELINK, available from Medtronic Corporation, Minneapolis, Minnesota, USA. ® The monitoring system includes computing devices.

[0026] External device 12 is configured to communicate wirelessly with IMD 10 and optionally with another computing device ( Figure 1 (Not illustrated) Communication. For example, external device 12 may communicate via near-field communication technology (e.g., inductive coupling, NFC, or other communication technology that can operate at a range of less than 10cm to 20cm) and far-field communication technology (e.g., according to 802.11 or Bluetooth). ® RF telemetry of the specification set or other communication technologies that can operate at a range greater than that of near-field communication technologies can be used for communication.

[0027] External device 12 can be used to configure the operating parameters of IMD 10. External device 12 can be used to retrieve data from IMD 10. The retrieved data may include values ​​of patient parameters measured by IMD 10, indications of arrhythmia episodes or other conditions detected by IMD 10, and physiological signals recorded by IMD 10. (See below for more information.) Figure 4In more detail, one or more remote computing devices may interact with IMD 10 via a network in a manner similar to external device 12, for example, to program IMD 10 and / or retrieve data from IMD 10.

[0028] The processing circuitry of the medical device system 2 (e.g., the processing circuitry of the IMD 10, the external device 12, and / or one or more other computing devices) can be configured to perform the example techniques disclosed herein for controlling the IMD 10 to selectively deliver cathode pacing or AC pacing based on patient parameters.

[0029] The IMD 10 can be coupled to the heart 8 via transvenous leads 16 and 18. The housing 15 of the IMD 10 can encapsulate internal circuitry corresponding to various circuits and components used for sensing cardiac signals from the heart 8 and delivering cardiac pacing therapy. In some examples, the IMD 10 can be configured to detect tachyarrhythmias from the sensed cardiac signals and deliver a high-voltage cardioversion / defibrillation (CV / DF) shock to the heart 8, for example, to terminate detected ventricular tachycardia or ventricular fibrillation.

[0030] Lead 16 may be an RA lead (“RA lead 16”), and lead 18 may be a ventricular conduction system pacing lead (“VCS pacing lead 18”). RA lead 16 and VCS pacing lead 18 may be advanced via a vein to position electrodes for sensing cardiac electrical signals and delivering pacing therapy. RA lead 16 may be positioned such that its distal end is in or near the right atrium. RA lead 16 may carry pacing and sensing electrodes 20 and 22, shown as a tip electrode and a ring electrode, respectively. Electrodes 20 and 22 provide sensing and pacing in the RA and are each connected to a corresponding insulated conductor extending within the elongated body of RA lead 16. IMD 10 may include a connector block configured to receive lead connectors for electrically connecting conductors extending from the distal electrodes 20 and 22 via an electrical feedthrough through housing 15 to circuitry within housing 15.

[0031] As shown in the figure, from the right atrial approach, the VCS lead 18 can be advanced within the right atrium to position the tip electrode 32 and the loop electrode 34 for pacing and sensing near the VCS (e.g., at or near the LBB). The VCS tip electrode 32 can be a helical electrode. The VCS tip electrode 32 can be advanced to the lower end of the atrial septum, below the AV node, and near the tricuspid annulus to position the tip electrode 32 within, along, or near the His bundle. The loop electrode 34, spaced proximally from the tip electrode 32, can be used as a return electrode, together with the cathode tip electrode 32, for pacing the right and left ventricles via the native His-Purkinje conduction system.

[0032] The IMD 10 can generate an intracardiac EGM signal from cardiac electrical signals received via a sensing electrode vector, which may include a tip electrode 32 and / or a loop electrode 34 of a VCS lead 18. Electrodes 32 and 34 are coupled to corresponding insulated conductors extending within the elongated body of the VCS lead 18, which provide an electrical connection to a proximal lead connector connected to the circuitry of the IMD 10 within the housing 15 via an electrical feedthrough through the housing 15.

[0033] The housing 15 can serve as a return electrode, used in conjunction with any of the electrodes carried by leads 16 and 18 for unipolar sensing or pacing configurations. Electrodes 32 and 34 can be used in bipolar pacing electrode pairs for delivering VCS pacing pulses and for receiving cardiac electrical signals to sense intrinsic and pacing-induced QRS waveforms. In some examples, the IMD 10 can be configured, for example, to use electrode 32 and housing 15 or electrode 34 and housing 15 to sense far-field (FF) cardiac signals, and / or, for example, to use electrode 32 and 34 to sense near-field (NF) cardiac signals for processing and analysis to determine the capture type. Electrodes 32 and 34 can be used in sensing electrode vectors to sense intrinsic R waves for determining the need for cardiac rhythm and electrical stimulation therapy.

[0034] exist Figure 1 In this embodiment, IMD 10 is a dual-chamber device configured to receive RA lead 16, which is positioned in the right atrial ventricle to deliver atrial pacing pulses and sense atrial electrical signals via electrodes 20 and 22. IMD 10 can be configured to sense the intrinsic atrial P wave and deliver atrial pacing pulses in the absence of a sensed P wave. IMD 10 can be configured to deliver atrial-synchronized ventricular pacing by setting an AV delay in response to each sensed P wave or delivered atrial pacing pulse and to deliver a ventricular pacing pulse to the VCS via lead 18 at the end of the AV delay.

[0035] VCS lead 18 can be advanced via RA into RV to position tip electrode 32 within interventricular septum 19. In various examples, tip electrode 32 can be selected as a pacing cathode electrode, combined with loop electrode 34 as a return anode electrode for pacing and capturing LBB and / or RBB. In some cases, pacing dose values ​​(e.g., pulse amplitude and / or pulse width) can be selected to achieve cathode capture at the cathode electrode for capturing at least one bundle branch. In some cases, pacing pulse amplitude and / or pulse width can be selected to achieve both cathode and anode capture, which can capture both LBB and the right side of the interventricular septum. In some cases, LBB and RBB can be captured concurrently to provide dual bundle branch (BB) pacing or bilateral bundle branch pacing using a single bipolar electrode pair.

[0036] In other examples, the tip electrode 32 or the loop electrode 34 may be selected as a cathode electrode paired with the housing 15 in a monopolar pacing electrode vector. Monopolar pacing can capture a single BB or location within the ventricle. Although the VCS lead 18 is shown carrying a pacing and sensing electrode pair (i.e., the tip electrode 32 and the loop electrode 34), it should be understood that in other examples, the VCS lead 18 may include multiple electrodes along its distal portion to provide one or more selectable bipolar pacing electrode vectors and / or one or more monopolar pacing electrode vectors (e.g., together with the housing 15) for delivering pacing pulses to the left and right sides of the interventricular septum.

[0037] Furthermore, when the IMD 10 is configured to deliver high-voltage shock therapy via an ICD, the VCS lead 18 may include one or more coil electrodes, such as coil electrode 35. Coil electrode 35 may be used in a sensing electrode vector, for example, together with either tip electrode 32 or loop electrode 34, for sensing a ventricular EGM signal, which may be analyzed by processing (e.g., of the IMD 10) of the system to classify the VCS pacing pulse capture type.

[0038] As described above, IMD 10 can communicate with external device 12 via wireless telemetry. External device 12 can receive and use data from IMD 10. Figure 1 The EGM signal, as shown or described in other examples or in the accompanying drawings, is sensed by any available electrode for processing and analysis in accordance with the techniques disclosed herein.

[0039] Although the IMD 10 is generally described herein as a pacemaker (including an intracardiac pacemaker) that delivers conduction system pacing and determines whether the pacing produces effective conduction system pacing, example systems including one or more implantable or external devices of any type configured to sense cardiac EGM can be configured to implement the techniques of this disclosure.

[0040] Figure 2 This is an example of one or more techniques described herein. Figure 1 A functional block diagram of an example configuration of IMD 10 is provided. In the illustrated example, IMD 10 includes electrodes 51, processing circuitry 50, sensing circuitry 52, communication circuitry 54, storage device 56, therapeutic delivery circuitry 58, and sensor 62, which may be located on one or more leads (e.g., lead 16). Electrode 51 may include electrodes described herein, such as electrodes 20, 22, 32, 34, etc.

[0041] Processing circuitry 50 may include fixed-function circuitry and / or programmable processing circuitry. Processing circuitry 50 may include any or more of a microprocessor, controller, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or equivalent discrete or analog logic circuitry. In some examples, processing circuitry 50 may include multiple components, such as one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs, and any combination of other discrete or integrated logic circuitry. The functionality attributed herein to processing circuitry 50 may be embodied in software, firmware, hardware, or any combination thereof.

[0042] Sensing circuitry 52 may be coupled to electrode 51. Sensing circuitry 52 can sense signals from electrode 51, for example, to generate cardiac EGM, in order to monitor the electrical activity of the heart. As an example, sensing circuitry 52 may also monitor signals from sensor 62, which may include one or more accelerometers, pressure sensors, and / or optical sensors. In some examples, sensing circuitry 52 may include one or more filters and amplifiers for filtering and amplifying signals received from electrode 51 and / or sensor 62. Sensing circuitry 52 may include switching circuitry for selecting electrode 51 and its polarity to sense the cardiac EGM signal described herein.

[0043] Sensing circuit 52 and / or processing circuit 50 may be configured to detect cardiac depolarization (e.g., atrial depolarization P waves, ventricular depolarization R waves, etc.) when the cardiac EGM amplitude exceeds a sensing threshold. In some examples, for cardiac depolarization detection, sensing circuit 52 may include a rectifier, filter, amplifier, comparator, and / or analog-to-digital converter. In some examples, sensing circuit 52 may output an indication to processing circuit 50 in response to sensing cardiac depolarization. In this way, processing circuit 50 may receive a detected cardiac depolarization indication corresponding to the presence of detected R and P waves in the corresponding chambers of the heart. Processing circuit 50 may use the indications of the detected R and P waves to determine the depolarization interval, heart rate, and detect arrhythmias, such as tachyarrhythmias and cardiac arrest.

[0044] The communication circuitry 54 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such as external device 12, another networked computing device, or another IMD or sensor. Under the control of the processing circuitry 50, the communication circuitry 54 may receive downlink telemetry from external device 12 or the other device and transmit uplink telemetry to or from that external device or the other device via an internal or external antenna. Furthermore, the processing circuitry 50 may communicate via external devices (e.g., external device 12) and computer networks (such as Medtronic CareLink).® The communication circuit 54 can communicate with networked computing devices via inductive coupling, electromagnetic coupling, near field communication (NFC), radio frequency (RF) communication, Bluetooth, WiFi, or other proprietary or non-proprietary wireless communication schemes.

[0045] In some examples, storage device 56 includes computer-readable instructions that, when executed by processing circuitry 50, cause IMD 10 and processing circuitry 50 to perform various functions accorded to IMD 10 and processing circuitry 50 herein. Storage device 56 may include any volatile, non-volatile, magnetic, optical, or electrical medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital medium. As an example, storage device 56 may store programmed values ​​of one or more operating parameters of IMD 10 and / or data collected by IMD 10 for transmission to another device using communication circuitry 54. Data stored by storage device 56 and transmitted by communication circuitry 54 to one or more other devices may include digitized cardiac EGM and other patient parameters.

[0046] The treatment delivery circuit 58 may be configured to generate electrical therapy (e.g., pacing pulses) and deliver it to the patient's heart 8 via electrode 51. In some examples, the treatment delivery circuit 58 may include a capacitor, a current source, and / or a regulator. The treatment delivery circuit 58 may include switching circuitry for selecting electrode 51 and its polarity to deliver a treatment signal to the heart 8. The treatment delivery circuit 58 may deliver electrical stimulation therapy via electrode 51 according to one or more treatment parameter values ​​that may be stored in storage device 56. In the case of pacing pulses, the treatment parameter values ​​may include magnitudes such as pulse amplitude and width.

[0047] IMD 10 can be configured to deliver LBBAP to provide synchronized left ventricular contraction via selective or non-selective stimulation of the LBB or pacing adjacent to the LBB on the left side of the interventricular septum. Asynchronous ventricular activation can be normalized or improved by applying LBBAP. If appropriate timing is applied to the LBBAP such that the pacing left ventricular activation merges with the native activation of the right ventricle, patients with primary left conduction interference can achieve both intraventricular and interventricular synchronization. Achieving this result may require appropriate selection of the AV delay used for LBBAP to match the patient's native AV conduction (e.g., as indicated by the interval between the P wave and the intrinsic R wave). For example, if the patient exhibits normal intrinsic AV conduction, appropriately timed LBBAP can provide AV synchronization as well as interventricular and intraventricular synchronization. Therefore, if the patient's intrinsic AV conduction is normal (e.g., the PR interval is equal to or less than 200 ms), the cathode capture of the LBBAP may be superior to AC pacing in the LBB region.

[0048] According to the technology of this disclosure, processing circuitry 50 can be configured to control therapeutic delivery circuitry 58 to selectively deliver cathodic pacing and AC pacing based on patient parameters. Generally, patient parameters can indicate the health condition of a patient who may be more responsive to cathodic pacing or bipolar stimulation. For example, a patient with atrioventricular block, atrial fibrillation, etc., may benefit more from AC pacing than from cathodic pacing. Therefore, selective delivery of cathodic pacing and AC pacing based on patient parameters can lead to better treatment and thus improved health outcomes. Generally, the technology and apparatus of this disclosure are applicable to any situation in which the IMD 10 is paced in a non-atrial tracking mode. The indication or determination of nonfunctional atrial leads (e.g., due to arrhythmias) is another possible use case for this technology and apparatus.

[0049] As an example, processing circuit 50 can control treatment delivery circuit 58 to deliver cathode or AC stimulation based on whether the patient has prolonged atrioventricular conduction (also known as primary cardiac block or type I AV block (or any other type of AV block, such as secondary cardiac block, tertiary cardiac block, etc.)). AV block is a cardiac conduction disorder characterized by slower or complete blockage of electrical signal transmission from the atria (upper ventricle) to the ventricles (lower ventricle) of the heart. In a healthy heart, electrical impulses travel smoothly and rapidly through the AV junction, which is responsible for transmitting signals between the atria and ventricles. For example, the PR interval in a healthy heart can be 200 milliseconds or less.

[0050] In some instances, processing circuitry 50 can determine whether a patient has prolonged atrioventricular conduction based on whether the patient's PR interval meets (e.g., exceeds) a threshold (e.g., 200 ms). If the patient's PR interval is equal to or less than the threshold, the patient may have a normal PR interval, indicating timely native activation of the right ventricle. Therefore, it may be desirable to fuse (e.g., mix or integrate) the cathodic pacing provided by lead 16 with the natural depolarization of the right ventricle.

[0051] Processing circuitry 50 can measure the interval between atrial sensing (or atrial pacing pulse) and ventricular sensing to measure the PR interval. A normal or inherent PR interval can be 200 milliseconds or less. For atrial pacing, assuming the atrial pacing rate does not overdrive the normal sinus rate, a normal PR interval can be approximately 250 milliseconds or less.

[0052] The therapeutic delivery circuit 58 can deliver cathodic pacing using the tip electrode 32 as the cathode and the housing 15 as ground. Alternatively, the therapeutic delivery circuit 58 can deliver cathodic pacing using the tip electrode 32 as the cathode and the ring electrode 34 as ground, but avoiding the magnitude of anodic stimulation at the ring electrode 34. In this latter example, the therapeutic delivery circuit 58 can deliver cathodic stimulation by outputting pulses with an amplitude equal to or less than 2 mA, although this amplitude may vary from patient to patient.

[0053] On the other hand, if a patient's PR interval is greater than the threshold, the patient may have prolonged atrioventricular conduction, indicating that the patient may no longer have timely native activation of the right ventricle. That is, if the patient's atrioventricular conduction is prolonged, hemodynamics will suffer from loss of AV synchronization, and the detrimental effects of this loss of AV synchronization may outweigh the benefits of fusion between LBBAP and native right ventricular activation. In this case, LBBAP may need to be applied earlier than optimal fusion between LBBAP and native right ventricular activation is required.

[0054] Processing circuitry 50 can control therapeutic delivery circuitry 58 to deliver AC pacing via tip electrode 32 and loop electrode 34 to activate both ventricles of heart 8. In other words, tip electrode 32 can be selected as the pacing cathode electrode, combined with loop electrode 34 as the return anode electrode, for pacing and capturing the ventricles based on patient parameters (e.g., delayed or absent AV conduction, as indicated by a threshold PR interval). For example, processing circuitry 50 can configure the pacing magnitude value of the pacing pulse delivered by therapeutic delivery circuitry 58. In some cases, the pacing pulse amplitude and / or pulse width can be selected to achieve only cathode capture at the cathode electrode. In other cases, the pacing pulse amplitude and / or pulse width can be selected to achieve both cathode and anode capture.

[0055] For example, processing circuit 50 can cause treatment delivery circuit 58 to deliver AC pacing by increasing the pulse amplitude (e.g., increasing it to 2.5 mA or greater), resulting in anodic stimulation by ring electrode 34. Anodic stimulation can activate the right ventricle, while cathodic stimulation activates the left ventricle, thereby correcting for long atrioventricular delay while providing interventricular and intraventricular synchronization in patients with long AV delay.

[0056] Processing circuitry 50 can be configured to determine the appropriate amplitude for capture. For example, when pacing tip-to-can or tip-to-loop (or, in some examples, tip-to-coil), processing circuitry 50 can determine the cathode threshold for capture. In some examples, processing circuitry 50 can pac from loop-to-can or loop-to-coil individually to determine the capture threshold for anodic stimulation. In some examples, processing circuitry 50 can analyze the timing of changes in EGM morphology or depolarization to reach a distant sensing location as pacing output changes. For example, processing circuitry 50 can pace tip-to-loop with low output. Processing circuitry 50 can use the EGM morphology as a baseline or reference for cathode capture while increasing the pacing amplitude from tip-to-loop. Processing circuitry 50 can determine when the EGM morphology changes from the baseline (in response to the increase in pacing amplitude) and thus determine the threshold for AC capture.

[0057] Although this document is primarily discussed in the context of AV blockade, it should be understood that the techniques disclosed herein can be applied in substantially similar ways to other medical conditions and other patient parameters. That is, the techniques disclosed herein can generally be applied to selectively deliver cathodic pacing or AC pacing based on whether patient parameters meet one or more criteria (e.g., by comparing patient parameters to thresholds). Moreover, it should be understood that the state of a given patient can change over time, such that cathodic pacing is preferred for that patient at one time, and AC pacing is preferred for that patient at another time. Therefore, the advantage of the techniques and apparatus disclosed herein is that they periodically monitor patient parameters (e.g., whether the patient's PR interval and / or AV delay is greater than 200 milliseconds) and respond to transient rhythm changes within the patient.

[0058] Figure 3 This is a block diagram illustrating an example configuration of the components of external device 12. Figure 3 In the example, the external device 12 includes a processing circuit 80, a communication circuit 82, a storage device 84, and a user interface 86.

[0059] Processing circuitry 80 may include one or more processors configured to implement functions and / or processing instructions for execution within external device 12. For example, processing circuitry 80 may be able to process instructions stored in storage device 84. Processing circuitry 80 may include, for example, a microprocessor, DSP, ASIC, FPGA, or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuits. Therefore, processing circuitry 80 may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions attributed to processing circuitry 80 herein.

[0060] The communication circuitry 82 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such as IMD 10. Under the control of the processing circuitry 80, the communication circuitry 82 may receive downlink telemetry from IMD 10 or the other device, and send uplink telemetry to IMD or the other device. The communication circuitry 82 may be configured to transmit or receive signals via inductive coupling, electromagnetic coupling, near field communication (NFC), radio frequency (RF) communication, Bluetooth, WiFi, or other proprietary or non-proprietary wireless communication schemes. The communication circuitry 82 may also be configured to communicate with devices other than IMD 10 via any of a variety of wired and / or wireless communication and / or network protocols.

[0061] Storage device 84 may be configured to store information within external device 12 during operation. Storage device 84 may include a computer-readable storage medium or a computer-readable storage device. In some examples, storage device 84 includes one or more of short-term memory or long-term memory. Storage device 84 may include, for example, RAM, DRAM, SRAM, magnetic disk, optical disk, flash memory, or various forms of EPROM or EEPROM. In some examples, storage device 84 is used to store data indicating instructions for execution by processing circuitry 80. Storage device 84 may be used by software or applications running on external device 12 to temporarily store information during program execution.

[0062] Data exchanged between external device 12 and IMD 10 may include operating parameters. External device 12 may transmit data including computer-readable instructions that, when implemented by IMD 10, control IMD 10 to change one or more operating parameters and / or export collected data. For example, processing circuitry 80 may transmit instructions to IMD 10 requesting IMD 10 to output collected data (e.g., digital cardiac EGM) to external device 12. Furthermore, external device 12 may receive data collected from IMD 10 and store the collected data in storage device 84. Processing circuitry 80 may implement any of the techniques described herein to control treatment delivery circuitry 58 to selectively deliver AC or cathode pacing via electrode 51.

[0063] Users, such as clinicians or patients, can interact with external device 12 through user interface 86. User interface 86 includes a display (not shown), such as a liquid crystal display (LCD) or a light-emitting diode (LED) display or other type of screen, which processing circuitry 80 can use to present information related to IMD 10, such as cardiac EGM, pacemaker values, etc. Furthermore, user interface 86 may include input mechanisms for receiving user input. Input mechanisms may include, for example, buttons, a keypad (e.g., an alphanumeric keypad), a peripheral pointing device, a touchscreen, or another input mechanism that allows the user to navigate and input through the user interface presented by processing circuitry 80 of external device 12. In other examples, user interface 86 may also include audio circuitry for providing auditory notifications, instructions, or other sounds to the user, receiving voice commands from the user, or both.

[0064] Figure 4 This is a block diagram illustrating an example system according to one or more technologies described herein. The example system includes an access point 90, a network 92, an external computing device (such as a server 94), and one or more other computing devices 100A to 100N (collectively, “Computing Device 100”), which can be connected to IMD 10 and external device 12 via network 92. In this example, IMD 10 can use communication circuitry 54 to communicate with external device 12 via a first wireless connection and with access point 90 via a second wireless connection. Figure 4 In the example, access point 90, external device 12, server 94 and computing device 100 are interconnected and can communicate with each other via network 92.

[0065] Access point 90 may include a device connected to network 92 via any of a variety of connections, such as dial-up, digital subscriber line (DSL), or cable modem connections. In other examples, access point 90 may be connected to network 92 via different forms of connections, including wired or wireless connections. In some examples, access point 90 may be a user device that can be co-located with the patient, such as a tablet or smartphone. IMD 10 may be configured to transmit data to access point 90, such as data regarding pacemaker values ​​and / or cardiac EGM. Access point 90 may then transmit the retrieved data to server 94 via network 92.

[0066] In some cases, server 94 may be configured to provide a secure storage site for data already collected from IMD 10 and / or external device 12. In some cases, server 94 may compile the data into web pages or other documents via computing device 100 for viewing by trained professionals such as clinicians. Figure 4 One or more aspects of the example system can be used with Medtronic CareLink ® The network provides general network technologies and functions similar to those used in general network technologies.

[0067] In some examples, one or more computing devices in computing device 100 may be tablet computers or other smart devices located with a clinician, who may program these devices to receive data and / or query IMD 10. For example, the clinician may access data collected by IMD 10 via computing device 100, such as when the patient is between clinician visits, to check the status of the medical condition or the operation of IMD 10. In some examples, the clinician may input instructions for medical interventions for the patient into an application executed by computing device 100, such as based on the status of the patient's condition determined by IMD 10, external device 12, server 94, or any combination thereof, or based on other patient data known to the clinician. Device 100 may then transmit the instructions for the medical intervention to another computing device in computing device 100 located with the patient or the patient's caregiver. For example, such instructions for medical intervention may include instructions to change medication dosage, timing, or selection, instructions to schedule a clinician visit, or instructions to seek medical attention. In another example, the computing device 100 can generate alerts to the patient based on the status of their medical condition, enabling the patient to proactively seek medical care before receiving instructions for medical intervention. In this way, the patient can take autonomous action as needed to address their medical condition, which can help improve the patient's clinical outcomes.

[0068] In the Figure 4In the illustrated example, server 94 includes, for example, a storage device 96 and processing circuitry 98 for storing data retrieved from IMD 10. Although Figure 4 Not illustrated herein, but computing device 100 may similarly include storage devices and processing circuitry. Processing circuitry 98 may include one or more processors configured to implement functional and / or procedural instructions for execution within server 94. For example, processing circuitry 98 may be able to process instructions stored in memory 96. Processing circuitry 98 may include, for example, a microprocessor, DSP, ASIC, FPGA, or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuits. Therefore, processing circuitry 98 may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions attributed to processing circuitry 98 herein. The processing circuitry 98 of server 94 and / or the processing circuitry of computing device 100 may implement any of the techniques described herein to analyze cardiac EGM received from IMD 10, for example, to determine whether AC pacing or cathode pacing is being delivered.

[0069] Storage device 96 may include a computer-readable storage medium or a computer-readable storage device. In some examples, storage device 96 includes one or more of short-term memory or long-term memory. Storage device 96 may include, for example, RAM, DRAM, SRAM, magnetic disk, optical disk, flash memory, or various forms of EPROM or EEPROM. In some examples, storage device 96 is used to store data indicating instructions for execution by processing circuitry 98.

[0070] Figure 5 This is a flowchart illustrating an example method for operating a medical device to transition from cathode LBBAP to anode-cathode left bundle branch region pacing and right septal pacing according to the technology of this disclosure. Although Figure 5 The example operation is described as being performed by the processing circuit 50 of the IMD 10, but in other examples, some or all of the operations in the example operation may be performed by the processing circuit of another device and with respect to any cardiac EGM.

[0071] The IMD 10 can sense one or more cardiac EGMs in a patient during ventricular pacing delivery. More specifically, the IMD 10 can pause the delivery of ventricular pacing for at least one sustained beat (resulting in a normal or intrinsic beat that is not disrupted by atrial premature contractions (PACs) or ventricular premature contractions (PVCs) and has a normal AA interval).

[0072] Processing circuit 50 can receive the cardiac EGM and identify heartbeats within the EGM (500). Processing circuit 50 can determine one or more patient parameters based on the heartbeats (502). Patient parameters may include atrioventricular synchronization measures, such as the PR interval and / or AV delay. For example, IMD 10 can measure the duration between IMD 10 pacing the atrium and IMD 10 sensing activity in the ventricle, the duration between IMD 10 sensing electrical activity in the atrium and IMD 10 sensing electrical activity in the ventricle, etc. These durations may represent or otherwise relate to the PR interval and / or other patient parameters. Based on the patient parameters, processing circuit 50 can control treatment delivery circuit 58 to deliver cathodic pacing or AC pacing, as some patients may benefit more from cathodic pacing and others may benefit more from AC pacing (504). In fact, a given patient may benefit more from cathodic pacing at one time and more from AC pacing at another time.

[0073] For example, patients experiencing prolonged atrioventricular conduction (e.g., periodically) may benefit more from AC pacing than from cathodic pacing. Therefore, processing circuit 50 may control treatment delivery circuit 58 to deliver AC pacing if the patient has prolonged atrioventricular conduction (e.g., as indicated by the patient's PR interval and / or AV delay) or when the patient has prolonged atrioventricular conduction, and deliver cathodic pacing if the patient has normal atrioventricular conduction. For example, processing circuit 50 may periodically determine whether a patient has prolonged atrioventricular conduction based on whether the patient's PR interval meets (e.g., exceeds) a threshold (e.g., 200 ms). If the patient's PR interval is equal to or less than the threshold, the patient may have a normal PR interval, indicating native activation of the right ventricle.

[0074] In response to a PR interval meeting a threshold, processing circuit 50 can control treatment delivery circuit 58 to deliver AC pacing. In response to a PR interval not meeting the threshold, processing circuit 50 can control treatment delivery circuit 58 to deliver cathode pacing. In this way, the technology and apparatus of this disclosure can allow for more personalized healthcare, potentially improving patient outcomes.

[0075] As another example, when a patient enters atrial fibrillation, atrial flutter, or atrial tachycardia, the pacemaker can switch to a non-atrial tracking mode. In non-tracking mode, timing of LBBAP or LBBP may not be possible to achieve fusion with the patient's inherent RV activation. Therefore, during non-tracking pacing, the IMD 10 can advantageously provide AC pacing. If the IMD 10 later switches back to atrial tracking mode (e.g., when atrial fibrillation terminates), ventricular pacing can switch back to cathode-only LBBAP or LBBP once the appropriate AV interval has been measured.

[0076] Another situation where AC pacing may benefit is when the IMD 10 switches to non-atrial tracking mode due to the observation that the atrial leads are no longer functioning, for example, when the measured atrial pacing impedance is out of range, or when the automatic determination of the atrial capture threshold cannot provide the detected atrial capture threshold.

[0077] The following examples illustrate the techniques described herein.

[0078] Example 1: A medical device system includes a medical device configured to deliver ventricular pacing to a patient's heart; and processing circuitry configured to: receive electrocardiogram (ECG) data of the patient sensed by the medical device during the delivery of ventricular pacing; identify one or more heartbeats within the ECG data; determine one or more patient parameters based on the one or more heartbeats; and control the medical device to deliver cathodic pacing or anodic-cathode pacing based on the one or more patient parameters.

[0079] Example 2: The medical device system according to Example 1, wherein the processing circuit is configured to control the medical device to deliver cathodic pacing or anodic-cathode pacing by determining whether at least one of the one or more patient parameters meets a threshold.

[0080] Example 3: The medical device system according to Example 2, wherein one or more patient parameters include atrioventricular synchronization measurements.

[0081] Example 4: The medical device system according to Example 3, wherein the atrioventricular synchronization measurement includes at least one of the PR interval or atrioventricular delay.

[0082] Example 5: According to the medical device system of Example 4, wherein the processing circuit is configured to: determine whether at least one of the PR interval or the atrioventricular delay meets the threshold; control the medical device to deliver anode-cathode pacing in response to at least one of the PR interval or the atrioventricular delay meeting the threshold; and control the medical device to deliver cathode pacing in response to at least one of the PR interval or the atrioventricular delay not meeting the threshold.

[0083] Example 6: The medical device system according to Example 5, wherein the processing circuit is configured to determine that at least one of the PR interval or the atrioventricular delay satisfies the threshold in response to at least one of the PR interval or the atrioventricular delay being greater than the threshold, and wherein the threshold is 200 milliseconds.

[0084] Example 7: A medical device system according to any one of Examples 1 to 6, wherein the processing circuit is configured to control the medical device to deliver anodic-cathode pacing to treat one or more of atrioventricular block or atrial fibrillation.

[0085] Example 8: A medical device system according to any one of Examples 1 to 7, wherein the medical device includes a lead configured to deliver the ventricular pacing, wherein the lead includes a cathode electrode and an anode electrode.

[0086] Example 9: The medical device system according to Example 8, wherein the cathode electrode is a tip electrode and wherein the anode electrode is a ring electrode.

[0087] Example 10: The medical device system according to Example 9, wherein the ventricular pacing includes left bundle branch region pacing.

[0088] Example 11: A medical device includes a cathode electrode configured to deliver ventricular pacing to a patient's heart; an anode electrode configured to deliver ventricular pacing to the heart; and processing circuitry configured to: receive electrocardiogram (ECG) data of the patient sensed by the medical device during ventricular pacing delivery; identify one or more heartbeats within the ECG data; determine one or more patient parameters based on the one or more heartbeats; and control the medical device to deliver cathode pacing or anode-cathode pacing based on the one or more patient parameters.

[0089] Example 12: The medical device according to Example 11, wherein the processing circuit is configured to control the medical device to deliver cathodic pacing or anodic-cathode pacing by determining whether at least one of the one or more patient parameters meets a threshold.

[0090] Example 13: The medical device according to Example 12, wherein one or more patient parameters include atrioventricular synchrony measurements.

[0091] Example 14: The medical device according to Example 13, wherein the atrioventricular synchronization measurement includes at least one of the PR interval or atrioventricular delay.

[0092] Example 15: The medical device according to Example 14, wherein the processing circuit is configured to: determine whether at least one of the PR interval or the atrioventricular delay meets the threshold; control the medical device to deliver anodic-cathode pacing in response to at least one of the PR interval or the atrioventricular delay meeting the threshold; and control the medical device to deliver cathode pacing in response to at least one of the PR interval or the atrioventricular delay not meeting the threshold.

[0093] Example 16: The medical device according to Example 15, wherein the processing circuit is configured to determine that at least one of the PR interval or the atrioventricular delay satisfies the threshold in response to at least one of the PR interval or the atrioventricular delay being greater than the threshold, and wherein the threshold is 200 milliseconds.

[0094] Example 17: A medical device according to any one of Examples 11 to 16, wherein the processing circuit is configured to control the medical device to deliver anodic-cathode pacing to treat one or more of atrioventricular block or atrial fibrillation.

[0095] Example 18: A medical device according to any one of Examples 11 to 17, wherein the medical device includes a lead wire, the lead wire including a cathode electrode and an anode electrode.

[0096] Example 19: The medical device according to Example 18, wherein the cathode electrode is a pointed electrode and wherein the anode electrode is a ring electrode.

[0097] Example 20: The medical device according to Example 19, wherein the ventricular pacing includes left bundle branch pacing.

[0098] Example 21: A method comprising: receiving electrocardiogram (ECG) data of a patient sensed by a medical device during delivery of ventricular pacing by a processing circuit; identifying one or more heartbeats within the ECG data by the processing circuit; determining one or more patient parameters by the processing circuit based on the one or more heartbeats; and controlling the medical device to deliver cathodic pacing or anodic-cathode pacing by the processing circuit based on the one or more patient parameters.

[0099] The techniques described in this disclosure can be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, aspects of these techniques can be implemented in one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic QRS circuits, and any combination of such components embodied in external devices, such as physician or patient programmers, simulators, or other devices. The terms “processor” and “processing circuit” can generally refer to any of the aforementioned logic circuits, alone or in combination with other logic circuits, or any other equivalent circuit, alone or in combination with other digital or analog circuits.

[0100] For each aspect implemented in software, at least some of the functionality of the systems and apparatus described in this disclosure may be embodied in instructions on a computer-readable storage medium, such as RAM, DRAM, SRAM, magnetic disk, optical disk, flash memory, or various forms of EPROM or EEPROM. Executable instructions are provided to support one or more aspects of the functionality described in this disclosure.

[0101] Furthermore, in some aspects, the functionality described herein can be housed within dedicated hardware and / or software modules. Describing different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be implemented by separate hardware or software components. Rather, the functionality associated with one or more modules or units can be performed by separate hardware or software components, or integrated within common or separate hardware or software components. Additionally, these techniques can be fully implemented in one or more circuit or logic elements. The techniques disclosed herein can be implemented in a variety of devices or apparatuses, including IMDs, external programmers, combinations of IMDs and external programmers, integrated circuits (ICs), or a set of ICs and / or discrete circuits residing in IMDs and / or external programmers.

Claims

1. A medical device system, the medical device system comprising: A medical device configured to deliver ventricular pacing to a patient's heart; and Processing circuit, the processing circuit being configured to: Receive electrocardiogram data of the patient sensed by the medical device during delivery of ventricular pacing; Identify one or more heartbeats within the electrocardiogram data; One or more patient parameters are determined based on the one or more heartbeats; as well as The medical device is controlled to deliver cathodic pacing or anodic-cathode pacing based on one or more patient parameters.

2. The medical device system of claim 1, wherein the processing circuitry is configured to control the medical device to deliver cathodic pacing or anodic-cathode pacing by determining whether at least one of the one or more patient parameters meets a threshold.

3. The medical device system of claim 2, wherein the one or more patient parameters include atrioventricular synchrony measurements.

4. The medical device system of claim 3, wherein the atrioventricular synchronization measurement includes at least one of the PR interval or atrioventricular delay.

5. The medical device system of claim 4, wherein the processing circuit is configured to: Determine whether at least one of the PR interval or the atrioventricular delay meets the threshold; The medical device is controlled to deliver anodic-cathode pacing in response to at least one of the PR interval or the atrioventricular delay satisfying the threshold; and The medical device is controlled to deliver cathode pacing in response to at least one of the PR interval or the atrioventricular delay not meeting the threshold.

6. The medical device system of claim 5, wherein the processing circuitry is configured to determine that at least one of the PR interval or the atrioventricular delay satisfies the threshold in response to at least one of the PR interval or the atrioventricular delay being greater than the threshold, and wherein the threshold is 200 milliseconds.

7. The medical device system according to any one of claims 1 to 6, wherein the processing circuit is configured to control the medical device to deliver anode-cathode pacing to treat one or more of atrioventricular block or atrial fibrillation.

8. The medical device system according to any one of claims 1 to 7, wherein the medical device includes a lead configured to deliver the ventricular pacing, wherein the lead includes a cathode electrode and an anode electrode.

9. The medical device system of claim 8, wherein the cathode electrode is a tip electrode, and wherein the anode electrode is a ring electrode.

10. The medical device system of claim 9, wherein the ventricular pacing includes left bundle branch region pacing.

11. A medical device, the medical device comprising: A cathode electrode configured to deliver ventricular pacing to the patient's heart; An anode electrode, configured to deliver ventricular pacing to the heart; and Processing circuit, the processing circuit being configured to: Receive electrocardiogram data of the patient sensed by the medical device during delivery of ventricular pacing; Identify one or more heartbeats within the electrocardiogram data; One or more patient parameters are determined based on the one or more heartbeats; as well as The medical device is controlled to deliver cathodic pacing or anodic-cathode pacing based on one or more patient parameters.

12. The medical device of claim 11, wherein the processing circuitry is configured to control the medical device to deliver cathodic pacing or anodic-cathode pacing by determining whether at least one of the one or more patient parameters meets a threshold.

13. The medical device of claim 12, wherein the one or more patient parameters include atrioventricular synchrony measurements.

14. The medical device of claim 13, wherein the atrioventricular synchronization measurement includes at least one of the PR interval or atrioventricular delay.

15. The medical device of claim 14, wherein the processing circuit is configured to: Determine whether at least one of the PR interval or the atrioventricular delay meets the threshold; The medical device is controlled to deliver anodic-cathode pacing in response to at least one of the PR interval or the atrioventricular delay meeting the threshold; and The medical device is controlled to deliver cathode pacing in response to at least one of the PR interval or the atrioventricular delay not meeting the threshold.

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