Modes of operation of implantable cardiac rhythm management devices co-implanted with ventricular assist devices

Abstract

An implantable cardiac rhythm management medical device is configured to switch from a first operating mode to a second ventricular assist device operating mode to detect arrhythmias and control the delivery of antiarrhythmic therapy during the ventricular assist device operating mode. The implantable medical device may receive a command from another medical device indicating that a ventricular assist device is to be co-implanted with the implantable medical device in a patient and switch from the first operating mode to the second operating mode in response to receiving the command. Switching from the first mode to the second mode may include adjusting at least one control parameter for controlling electrical stimulation therapy that may be delivered by the implantable cardiac rhythm management medical device.

Description

Technical Field

[0001] The present disclosure relates to an implantable medical device (IMD) for cardiac rhythm management that can be co-implanted with a ventricular assist device (VAD) and can be configured for a VAD mode of operation. Background Art

[0002] A VAD is an implantable blood pump that assists a damaged heart by pumping blood to support the heart's workload. A VAD can be coupled along the arterial system, such as between a ventricular chamber and an artery, to pump blood from the ventricle into the arterial system. For example, a left ventricular assist device, or LVAD, can be coupled between the left ventricle and the ascending or descending aorta. Assistance in pumping blood through a VAD can be provided to patients with acute or chronic heart failure as a bridge to heart transplantation, as temporary support to allow myocardial recovery, or as a permanent assist device for heart failure patients for whom heart transplantation is contraindicated.

[0003] Cardiac rhythm management devices such as pacemakers or implantable cardioverter-defibrillators (ICDs) monitor the patient's heart rhythm and provide electrical stimulation therapy in response to the detection of abnormal electrical rhythms, such as bradycardia pacing, cardiac resynchronization therapy (CRT), anti-tachycardia pacing (ATP) or cardioversion / defibrillation (CV / DF) shocks. ICDs are generally designed to detect life-threatening ventricular tachyarrhythmias and respond quickly to detection by preparing and delivering ATP and / or one or more cardioversion or defibrillation shocks to prevent sudden cardiac death. Patients with heart failure are at risk of sudden cardiac death due to arrhythmias. ICD implantation in patients with heart failure reduces the risk of sudden cardiac death. The survival rate of patients with both VADs and ICDs can be improved. Summary of the invention

[0004] The technology of the present disclosure generally relates to an IMD that can be co-implanted with a VAD and can be configured to operate in a VAD mode to monitor a patient's heart rhythm and / or control therapy delivered by the IMD when the VAD is present. The VAD mode can include withholding or delaying shock therapy that is normally delivered when a ventricular tachyarrhythmia is detected during the normal, non-VAD operating mode of the IMD. The co-implanted VAD can provide the patient with necessary hemodynamic support during sustained ventricular tachyarrhythmias, thereby reducing the urgency of automatic cardioversion / defibrillation shocks in some instances of the IMD's VAD operating mode.

[0005] In one example, the present disclosure provides an IMD comprising a sensing circuit, a therapy delivery circuit, a telemetry circuit, and a control circuit. The sensing circuit is configured to receive a cardiac electrical signal generated by a patient's heart. The therapy delivery circuit is configured to generate an electrical stimulation therapy for delivery to the patient's heart. The telemetry circuit is configured to receive a command from another medical device indicating that a VAD is co-implanted with the IMD in the patient's body. The control circuit is coupled to the sensing circuit, the therapy delivery circuit, and the telemetry circuit and is configured to operate in a first mode, the first mode comprising detecting an arrhythmia from the cardiac electrical signal, and controlling the therapy delivery circuit to automatically deliver the electrical stimulation therapy in response to detecting the arrhythmia. The control circuit is further configured to switch from operating in the first mode to operating in a second mode in response to receiving the command. Switching to the second mode comprises adjusting at least one control parameter for controlling the electrical stimulation therapy.

[0006] In another example, the present disclosure provides a method performed by an IMD. The method includes operating the implantable medical device according to a first mode, receiving a command from another medical device indicating that a ventricular assist device is to be co-implanted with the implantable medical device in a patient, and switching from the first operating mode to a second operating mode in response to receiving the command. The first mode includes detecting an arrhythmia from a cardiac electrical signal and automatically delivering electrical stimulation therapy to the patient's heart in response to detecting the arrhythmia. Switching from the first mode to the second mode includes adjusting at least one control parameter for controlling the electrical stimulation therapy.

[0007] In yet another example, the present disclosure provides a non-transitory computer-readable storage medium storing a set of instructions that, when executed by a controller of an IMD, cause the IMD to receive a command from another medical device instructing to co-implant a VAD with the IMD in a patient, and in response to receiving the command, switch from a first operating mode to a second operating mode. Operating according to the first mode includes detecting an arrhythmia from cardiac electrical signals received by a sensing circuit of the IMD and controlling a therapy delivery circuit to automatically deliver electrical stimulation therapy to the patient's heart in response to detecting the arrhythmia. Switching from the first mode to the second mode includes adjusting at least one control parameter for controlling the electrical stimulation therapy.

[0008] In yet another example, the present disclosure provides an external programmer for programming an IMD. The programmer includes: a display; a telemetry circuit configured to communicate bidirectionally with the IMD; and a processor configured to generate a user interface on the display. The user interface includes a VAD mode window for receiving user input to enable a VAD operation mode of the IMD. The processor is further configured to control the telemetry circuit to transmit a VAD operation mode command to the IMD in response to the user input enabling the VAD operation mode.

[0009] The details of one or more aspects of the disclosure are set forth in the following drawings and description. Other features, objects, and advantages of the techniques described in this disclosure will be apparent from the description and drawings, and from the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1A and 1B is a conceptual diagram of an IMD system including an ICD and a VAD coupled to a patient's heart, according to one example.

[0011] Figure 2 is a conceptual diagram of a patient implanted with an IMD system including an ICD and a VAD according to another example.

[0012] Figure 3 is a schematic diagram of an ICD that may be co-implanted with a VAD and configured to operate in a VAD mode, according to one example.

[0013] Figure 4 is a schematic diagram of a pacemaker that may be co-implanted with a VAD and configured to operate in a VAD mode, according to one example.

[0014] Figure 5 is a flow chart of a method performed by an ICD according to one example.

[0015] Figure 6 is a flow chart of a method performed by an ICD operating in a VAD mode, according to one example.

[0016] Figure 7 is a flow chart of an ICD operation during VAD mode according to another example.

[0017] Figure 8 is a conceptual diagram of a user interface that may be generated by a processor of an external programmer for display to a user to program a VAD mode. DETAILED DESCRIPTION

[0018] In general, the present disclosure describes a cardiac rhythm management IMD that can be configured to operate in an altered or adjusted operating mode when a VAD is co-implanted with the IMD. A VAD operating mode, also referred to herein as a "VAD mode," can include one or more adjusted therapy control parameters for controlling the delivery of cardiac electrical stimulation therapy delivered by the IMD. A VAD operating mode can include one or more adjusted detection and detection control parameters used by the IMD to detect patient conditions such as arrhythmias. A VAD operating mode includes adjustments to IMD control parameters used to deliver therapy and / or detect arrhythmias, for example, to take into account the hemodynamic support provided by the VAD.

[0019] For example, in the absence of a VAD, arrhythmias that may typically cause symptoms or be life-threatening to the patient may be tolerable for extended periods of time when the patient is supported by a VAD. Thus, when a patient has a VAD that maintains hemodynamic stability even in the presence of a persistent arrhythmia, the delivery of CV / DF shocks, or other arrhythmia therapies that may cause pain and anxiety to the patient may be prevented or delayed. When a VAD is not co-implanted in the patient, the potentially life-threatening ventricular tachycardia (VT) or ventricular fibrillation (VF) may be treated with ATP or CV / DF shocks within seconds of detection of the ventricular tachycardia (VT) or ventricular fibrillation (VF) in the "non-VAD" operating mode of the IMD. However, when a VAD is co-implanted in the patient, since the VAD allows the patient to maintain a hemodynamically stable state, it is conceivable that CV / DF shock therapy may be withheld for minutes, hours, and even days to terminate VT or VF. For example, in the presence of a VAD, the ICD may not need to respond as quickly to a detected ventricular tachyarrhythmia as when the ICD is not co-implanted with the VAD. A patient with a VAD and an ICD may benefit from less urgent and / or less invasive therapy delivered by the ICD. Thus, in the VAD operating mode, tachyarrhythmia detection control parameters and / or therapy delivery control parameters as well as patient or clinician alarm conditions may be adjusted compared to the normal operating mode of the IMD when the VAD is not co-implanted with the IMD.

[0020] The examples presented herein relate to a cardiac rhythm management IMD provided as an ICD, which is capable of high-voltage electrical stimulation therapy, such as CV / DF shock. The ICD may be capable of delivering relatively low-voltage electrical stimulation therapy, such as cardiac pacing pulses for bradycardia pacing, post-shock pacing, CRT, and ATP. It should be recognized that various aspects of the technology disclosed herein can be implemented in a pacemaker or other cardiac rhythm management IMD, which can be configured to deliver cardiac pacing therapy without high-voltage CV / DF shock therapy capabilities. Thus, although the following examples primarily relate to an ICD, the practice of the technology disclosed herein is not necessarily limited to use with an ICD that can be co-implanted with a VAD, and may also be practiced in other IMDs configured to monitor a patient's heart rhythm and deliver cardiac electrical stimulation therapy.

[0021] For example, a pacemaker configured to deliver pacing therapy, which may include bradycardia pacing, post-shock pacing, CRT, and / or ATP as examples, may be configured to operate in a VAD mode of operation as disclosed herein. A pacemaker operating in a VAD mode may be a leadless pacemaker that is submuscular, subcutaneous, or fully implanted within a heart chamber (intracardiac) with electrodes mounted on a pacemaker housing. In other examples, a pacemaker operating in a VAD mode may be implanted in a subcutaneous or submuscular pocket and may be coupled to an extracardiac or transvenous cardiac lead extending from the pacemaker as a supplement or alternative to one or more electrodes on the pacemaker housing.

[0022] Figure 1A and 1B is a conceptual diagram of an IMD system 10 including an ICD 14 and a VAD 100 coupled to a patient's heart 8, according to one example. In some examples, an intracardiac pacemaker 80 may be included in the IMD system 10 or may be co-implanted with the VAD 100 without the ICD 14. Figure 1A is a front view of IMD system 10 implanted in patient 12 . Figure 1B1 is a lateral view of an IMD system 10 implanted in a patient 12. The ICD 14 is coupled to an external cardiovascular lead 16 that carries one or more electrodes for sensing cardiac electrical signals and for delivering cardiac electrical stimulation therapy. The VAD 100 is shown as an implantable blood pump 101 fluidly coupled between the ventricle and artery of the patient 12. In the example shown, the blood pump 101 is electrically coupled to an external wearable controller 110 via a percutaneous drive line 120. However, it should be recognized that in other examples, a VAD that can be co-implanted with an ICD 14 can include a fully implantable blood pump and controller, or an external blood pump and controller. In some examples, the blood pump and controller can be integrated together. Although a single VAD is shown in FIG. 1, it should be recognized that multiple VADs can be co-implanted with an ICD 14 and / or a pacemaker 80 (or other cardiac rhythm management device), for example, to provide biventricular assist using two blood pumps.

[0023] ICD 14 includes a housing 15 that forms an airtight seal that protects the internal components of ICD 14. The housing 15 of ICD 14 can be formed of a conductive material such as titanium or a titanium alloy. The housing 15 can act as an electrode (sometimes referred to as a "can" electrode). The housing 15 can be used as an active can electrode for delivering cardioversion / defibrillation (CV / DF) shocks or other high-voltage pulses delivered using a high-voltage therapy circuit. In other examples, the housing 15 can be used to deliver unipolar low-voltage cardiac pacing pulses and / or for sensing cardiac electrical signals and electrodes carried by lead 16. In other examples, the housing 15 of ICD 14 can include multiple electrodes on an external portion of the housing. One or more external portions of the housing 15 that act as one or more electrodes can be coated with a material such as titanium nitride, for example, to reduce post-stimulation polarization artifacts.

[0024] The ICD 14 is connected to an extracardiovascular electrical stimulation and sensing lead 16. The ICD 14 includes a connector assembly 17 (also referred to as a connector block or connector header) that includes electrical feedthroughs that span the housing 15 to provide electrical connections between conductors extending within a lead body 18 of the lead 16 and electronic components contained within the housing 15 of the ICD 14. As will be described in further detail herein, the housing 15 may house one or more processors, memory, transceivers, cardiac electrical signal sensing circuitry, therapy delivery circuitry, power supplies, and other components for sensing cardiac electrical signals, detecting cardiac rhythms, controlling and delivering electrical stimulation pulses to treat abnormal cardiac rhythms, and for communicating with an external programmer 40. In some instances, the ICD 14 may be configured to communicate with a VAD 100.

[0025] The elongated lead body 18 has a proximal portion 27 including a lead connector (not shown) configured to connect to the ICD connector assembly 17 and a distal portion 25 including one or more electrodes. Figure 1A and 1B In the illustrated example, distal portion 25 of lead body 18 includes defibrillation electrodes 24 and 26 and pacing / sensing electrodes 28 and 30. In some cases, defibrillation electrodes 24 and 26 may together form a defibrillation electrode, as they may be configured to be activated simultaneously. Alternatively, defibrillation electrodes 24 and 26 may form separate defibrillation electrodes, in which case each of electrodes 24 and 26 may be independently activated. In other examples, lead 16 may include only a single defibrillation electrode or more than two defibrillation electrodes.

[0026] Electrodes 24 and 26 (and in some instances, housing 15) are referred to herein as defibrillation electrodes because they are used, individually or collectively, to deliver high voltage stimulation therapy (e.g., cardioversion or defibrillation shocks). Electrodes 24 and 26 can be elongated coil electrodes and typically have a relatively large surface area for delivering high voltage electrical stimulation pulses compared to pacing electrodes 28 and sensing electrodes 30. However, in addition to or as an alternative to high voltage stimulation therapy, electrodes 24 and 26 and housing 15 can also be used to provide pacing functions, sensing functions, or both pacing and sensing functions. In this sense, the use of the term "defibrillation electrodes" herein should not be construed as limiting electrodes 24 and 26 to be used only in high voltage CV / DF shock therapy applications. For example, electrodes 24 and 26 can be used in a sensing vector for sensing cardiac electrical signals and detecting and distinguishing arrhythmias.

[0027] Electrodes 28 and 30 are relatively small surface area electrodes that can be used for sensing electrode vectors to sense cardiac electrical signals and, in some configurations, can be used to deliver relatively low voltage pacing pulses. Electrodes 28 and 30 are referred to as pacing / sensing electrodes because they are typically configured for low voltage applications, as opposed to delivering high voltage cardioversion defibrillation shocks, e.g., as cathodes or anodes for delivering pacing pulses and / or sensing cardiac electrical signals. In some cases, electrodes 28 and 30 can provide only pacing functionality, only sensing functionality, or both.

[0028] ICD 14 can obtain cardiac electrical signals corresponding to the electrical activity of heart 8 through one or more sensing vectors, wherein the sensing vector includes a combination of electrodes 24, 26, 28 and / or 30. In some instances, the housing 15 of ICD 14 is used in combination with one or more electrodes of electrodes 24, 26, 28 and / or 30 in the sensing electrode vector. In one instance, the sensing vector includes electrodes 28 and 30. In another instance, the sensing vector includes defibrillation electrodes 24 and housing 15. These examples are illustrative in nature and not restrictive. Various sensing electrode vectors utilizing a combination of electrodes 24, 26, 28 and 30 with housing 15 can be used to obtain one or more cardiac electrical signals received by a sensing circuit system included in ICD 14.

[0029] exist Figure 1A and 1B In the example shown, electrode 28 is positioned near defibrillation electrode 24, and electrode 30 is positioned between defibrillation electrodes 24 and 26. Lead 16 may include none, one, two, or more pacing / sensing electrodes, which, when present, may be carried at other locations along lead body 18 in addition to the specific locations shown. Electrodes 28 and 30 are shown as ring electrodes, but may include any of a variety of different types of electrodes, including ring electrodes, short coil electrodes, hemispherical electrodes, directional electrodes, segmented electrodes, etc.

[0030] Electrical conductors (not shown) extend from the lead connector at the proximal lead end 27 through one or more lumens of the elongated lead body 18 of the lead 16 to electrodes 24, 26, 28, and 30 positioned along the distal portion 25 of the lead body 18. The elongated electrical conductors contained within the lead body 18, which may be separate respective insulated conductors within the lead body 18, are electrically coupled to respective defibrillation electrodes 24 and 26 and pacing / sensing electrodes 28 and 30, respectively. The respective conductors electrically couple the electrodes 24, 26, 28, and 30 to circuitry of the ICD 14, such as therapy delivery circuitry and / or sensing circuitry, through connections in the connector assembly 17, which includes associated electrical feedthroughs that span the housing 15. The electrical conductors transmit therapy from the therapy delivery circuit within ICD 14 to one or more of the defibrillation electrodes 24 and 26 and / or the pacing / sensing electrodes 28 and 30, and transmit sensed electrical signals from the defibrillation electrodes 24 and 26 and / or the pacing / sensing electrodes 28 and 30 to the sensing circuit within ICD 14.

[0031] The lead body 18 of the lead 16 can be formed of a non-conductive material including silicone, polyurethane, fluoropolymer, mixtures thereof, and other suitable materials, and is shaped to form one or more lumens in which one or more conductors extend. The lead body 18 can be tubular or cylindrical. In other examples, the distal portion 25 (or all of it) of the elongated lead body 18 can have a flat, ribbon-like or paddle-like shape. The lead body 18 can be formed to have a preformed distal portion 25 that is generally straight, curved, bent, serpentine, wavy or zigzag.

[0032] In the example shown, the lead body 18 includes a curved distal portion 25 having two "C"-shaped curves, which together may resemble the Greek letter epsilon "epsilon". Defibrillation electrodes 24 and 26 are each carried by one of the two corresponding C-shaped portions of the lead body distal portion 25. The two C-shaped curves are seen extending or bending in the same direction away from the central axis of the lead body 18, along which the pacing / sensing electrodes 28 and 30 are located. In some cases, the pacing / sensing electrodes 28 and 30 may be substantially aligned with the central axis of the straight proximal portion of the lead body 18, such that the midpoints of the defibrillation electrodes 24 and 26 are laterally offset from the pacing / sensing electrodes 28 and 30.

[0033] Other examples of cardiovascular external leads that can be implemented with the techniques described herein and include one or more defibrillation electrodes carried by a curved, serpentine, wavy, or zigzag distal portion of the lead body 18 and one or more pacing electrodes and sensing electrodes are generally disclosed in pending U.S. Patent Publication No. 2016 / 0158567 (Marshall et al.). However, the techniques disclosed herein are not limited to any particular lead body design. In other examples, the lead body 18 is a flexible, elongated lead body without any preformed shape, bend, or bend. Various example configurations and sizes of cardiovascular external leads and electrodes that can be implemented in conjunction with the therapy management techniques disclosed herein are described in pending U.S. Publication No. 2015 / 0306375 (Marshall et al.) and pending U.S. Patent Publication No. 9,855,414 (Marshall et al.).

[0034] Lead 16 is shown extending centrally from connector assembly 27 of ICD 14, extending subcutaneously or submuscularly over thorax 32 of patient 12 toward the center of the torso, e.g., toward xiphoid process 20. At a location near xiphoid process 20, lead 16 bends or turns and extends superiorly and inferiorly beneath the thorax and / or sternum and substantially parallel to sternum 22. Anterior mediastinum 36 (see Figure 1B ) can be considered to be bounded laterally by the pleura 39, posteriorly by the pericardium 38, and anteriorly by the sternum 22 (see Figure 1B). The distal portion 25 of the lead 16 can extend along the posterior side of the sternum 22 substantially within the loose connective tissue and / or substernal musculature of the anterior mediastinum 36. A lead implanted so that the distal portion 25 is substantially within the anterior mediastinum 36 can be referred to as a "substernal lead."

[0035] exist Figure 1A and 1B In the illustrated example, lead 16 is positioned substantially centered beneath sternum 22. However, in other cases, lead 16 may be implanted such that it is laterally offset from the center of sternum 22. In some cases, lead 16 may extend laterally such that distal portion 25 of lead 16 is below / under thoracic cavity 32 in addition to or as an alternative to sternum 22. In other examples, distal portion 25 of lead 16 may be implanted in other extra-cardiovascular, intra-thoracic locations, including and adjacent to the periphery of the pleural cavity or pericardium 38 of heart 8. In other embodiments, distal portion 25 of lead 16 may be implanted in other extra-cardiovascular locations, such as subcutaneously, submuscularly, or in other extra-thoracic locations.

[0036] The ICD 14 is shown implanted subcutaneously on the left side of the patient 12 along the thorax 32. In some cases, the ICD 14 may be implanted between the left posterior axillary line and the left anterior axillary line of the patient 12. However, the ICD 14 may be implanted at other subcutaneous or submuscular locations of the patient 12. For example, the ICD 14 may be implanted in a subcutaneous pocket in the pectoralis region. In this case, the lead 16 may extend from the ICD 14 subcutaneously or submuscularly toward the handle of the sternum 22, and bend or turn and extend downward from the handle subcutaneously or submuscularly to the desired location. In yet another example, the ICD 14 may be placed in the abdomen. The access of the cardiovascular external lead 16 may depend on the location of the ICD 14, the arrangement and location of the electrodes carried by the lead body 18, the location of the VAD 100, and / or other factors.

[0037] The ICD 14 analyzes cardiac electrical signals received from one or more sensing electrode vectors to monitor abnormal rhythms, such as bradycardia, supraventricular tachycardia (SVT), VT, and VF. The ICD 14 can analyze the heart rate and the morphology of the cardiac electrical signals to monitor tachyarrhythmias according to any of a variety of tachyarrhythmia detection techniques. An example technique for detecting tachyarrhythmias is described in U.S. Patent No. 7,761,150 (Ghanem et al.). Various arrhythmia detection algorithms can be implemented in the ICD 14 to detect abnormal heart rhythms.

[0038] In response to detecting a tachyarrhythmia (e.g., VT or VF), the ICD 14 may generate and deliver electrical stimulation therapy using a therapy delivery electrode vector that may be selected from any of the available electrodes 24, 26, 28, 30 and / or the housing 15. The ICD 14 may deliver ATP in response to VT detection, and in some cases may deliver ATP prior to a CV / DF shock or during charging of a high voltage capacitor in an attempt to avoid the need to deliver a CV / DF shock. If the ATP fails to successfully terminate VT or VF is detected, the ICD 14 may deliver one or more CV / DF shocks through one or both of the defibrillation electrodes 24 and 26 and / or the housing 15. The ICD 14 may deliver CV / DF shocks using electrodes 24 and 26, either individually or together, as cathodes (or anodes) and the housing 15 as an anode (or cathode). ICD 14 may use a pacing electrode vector including one or more of electrodes 24 , 26 , 28 , and 30 and housing 15 of ICD 14 to generate and deliver other types of electrical stimulation pulses, such as post-shock pacing pulses or bradycardia pacing pulses.

[0039] External programmer 40 is shown in telemetric communication with ICD 14 via communication link 42. External programmer 40 may include processor 52, memory 53, display unit 54, user interface 56, and telemetry unit 58. Processor 52 controls external programmer operation and processes data and signals received from ICD 14. Display unit 54 may include a graphical user interface to display data, programmable selections and settings, and other information to a user to view ICD operation, program operating parameters and modes, and view cardiac electrical signals retrieved from ICD 14. For example, a user may use the graphical user interface of display unit 54 to select a VAD operating mode and program any user-programmable settings for the VAD operating mode, as described below in conjunction with Figure 8 Further described.

[0040] User interface 56 may include a mouse, touch screen, keyboard, etc. to enable a user to interact with external programmer 40 to initiate a telemetry session with ICD 14 to retrieve data from and / or transmit data to ICD 14. Telemetry unit 58 includes a transceiver and antenna configured for bidirectional communication with telemetry circuitry included in ICD 14 and configured to operate in conjunction with processor 52 to send and receive data related to ICD functions via communication link 42. The user interface 56 may be configured to communicate with external programmer 40 to initiate a telemetry session with ICD 14 to retrieve data from and / or transmit data to ICD 14. Telemetry unit 58 may include a transceiver and antenna configured for bidirectional communication with telemetry circuitry included in ICD 14 and configured to operate in conjunction with processor 52 to send and receive data related to ICD functions via communication link 42. A radio frequency (RF) link such as Wi-Fi or Medical Implant Communications Service (MICS) or other RF or communications frequency bandwidth establishes a communications link 42 between ICD 14 and external programmer 40 .

[0041] The external programmer 40 may be embodied as a programmer used in a hospital, clinic, or physician's office to retrieve data from the ICD 14 and program operating parameters and algorithms in the ICD 14 to control ICD functions. The external programmer 40 may alternatively be embodied as a home monitor or handheld device. The external programmer 40 may be used to program cardiac event sensing parameters (e.g., R-wave sensing parameters), cardiac rhythm detection parameters (e.g., the number of VT or VF intervals required to detect VT or VF events, respectively), and therapy control parameters used by the ICD 14. Data stored or acquired by the ICD 14, including physiological signals or associated data derived therefrom, results of device diagnostics, and a history of detected rhythm events and delivered therapies, may be retrieved from the ICD 14 by the external programmer 40 following an interrogation command.

[0042] The external programmer 40 may be used to enable the VAD mode of the ICD 14. The clinician or other authorized user may enable the VAD mode. The authorized user may enable the VAD mode by selecting a VAD mode "button" or field on a display screen of the external programmer 40. When the VAD is not present, the user may be required or prompted to enter one or more authentication entries to confirm the co-implantation of the VAD and prevent inappropriate or unintentional programming of the ICD 14 in the VAD mode. For example, entry of a VAD model and / or serial number or other patient-specific information may be required to confirm and authenticate the co-implantation of the VAD 100 with the ICD 14. In some instances, the controller 110 of the VAD 100 and the ICD 14 may be configured to communicate via wireless telemetry, in which case the VAD 100 may transmit a signal to the ICD 14 to confirm the co-implantation and verify the VAD mode of operation of the ICD 14.

[0043] The VAD mode may be enabled by selecting a single button or field on the external programmer display 54, which subsequently results in the transmission of a VAD mode command to the ICD 14. In other instances, the VAD 100 may transmit a communication signal to notify the ICD 14 of the presence of the co-implanted VAD 100. The ICD 14 may respond to receiving the VAD mode command by automatically adjusting arrhythmia detection parameters, therapy parameters, monitoring parameters, and / or alarm parameters according to default VAD mode operating control parameters. In other instances, additional user-programmable settings for the VAD mode may be selected by a user interacting with the external programmer 40 and programmed in the ICD 14 via uplink telemetry to the ICD 14.

[0044] In the example shown, VAD 100 includes an implantable blood pump 101 and an external wearable controller 110. VAD 100 can take the form of any of a variety of blood pumps, such as an impeller-driven or pneumatically-driven pump that provides pulsatile or non-pulsatile flow, an extracorporeal membrane oxygenation (ECMO) system, an intra-aortic balloon pump, or other mechanical circulatory support device configured to assist the mechanical pumping function of the heart. In the example of FIG. 1 , blood pump 101 can be a centrifugal, rotary blood pump having a pump housing 102 that encloses an internal pump chamber and a rotating impeller. Figure 1B As best seen, the blood pump 101 is shown coupled between the patient's heart 8 and an artery. For example, the blood pump 101 can be coupled between the left ventricle (LV) and the ascending aorta 6 to pump blood parallel to the LV into the arterial system. The internal pump chamber is in fluid communication with an inflow cannula 104 that can be inserted into the LV, for example, by a sewn ring, to receive blood from the patient's heart 8. At least a portion of the outer circumferential surface of the inflow cannula 104 can be sintered to promote tissue adhesion between the ventricular muscle and the inflow cannula 104. The pump housing 102 can have a relatively low profile, for example, an overall height of 30 mm or less, so that in some instances, the pump housing 102 can be implanted into the pericardial cavity. To accommodate implantation in the pericardial cavity, the inflow cannula 104 can be relatively short, for example, 60 mm or less. In other instances, the blood pump 101 can be implanted in the thoracic cavity but outside the pericardial cavity, or can be an external, wearable blood pump.

[0045] The interior of the pump housing 102 is also in fluid communication with an outflow port 106 coupled to an outflow vascular graft 108. The graft 108 is anastomosed with the ascending aorta 6 (or other artery) to direct the pump outflow into the patient's arterial system. In some examples, the graft 108 can be a graft with a diameter of 8 to 12 mm made of a polyester material. The graft 108 can include a strain relief member 107 to prevent kinking of the vascular graft 108. The strain relief member 107 can extend outwardly from the outflow port 106 along at least a portion of the length of the vascular graft 108. The strain relief member 107 can be formed of a coiled metal or plastic material that provides flexibility but kink resistance to the proximal portion of the vascular graft 108.

[0046] The controller 110 is shown as a wearable device that includes one or more rechargeable batteries and / or a power connection (e.g., an AC power connection) to power the controller 110. In other examples, the controller 110 can be implantable and can include a percutaneous rechargeable power source. The blood pump 101 can include a motor stator that receives a drive current from the controller 110 via a percutaneous drive wire 120. The VAD 100 can be a continuous flow pump and can have a constant or variable speed, such as the pump generally disclosed in U.S. Pat. No. 9,433,714 (Voskoboynikov et al.).

[0047] Figure 1A and 1B The present invention is illustrative in nature and should not be considered to limit the practice of the technology disclosed herein. For example, the implantation location of ICD 14, lead 16 and blood pump 101 can be different from Figure 1A and 1B In addition, other ICD and guidance systems and / or other VAD systems may replace the example ICD 14 and VAD 100 shown in system 10 and be configured to perform the techniques disclosed herein. For example, VAD 100 may be a fully implantable device.

[0048] In some examples, an intracardiac pacemaker 80 can be co-implanted with the VAD 100. The intracardiac pacemaker 80 includes a housing 82 that encloses internal circuitry and components for receiving cardiac electrical signals generated by the heart 8 through electrodes 84 and 86 on the housing 82. The housing 82 encloses a pulse generator for generating cardiac pacing pulses delivered to the heart 8 through the electrodes 84 and 86. The pacemaker 80 can be configured to deliver bradycardia pacing pulses, ATP, post-shock pacing pulses, CRT, atrial synchronized ventricular pacing, or other pacing therapies. The pacemaker 80 can be configured to switch to a VAD operating mode in response to a command received from an external programmer 40 or a communication signal from the VAD 100 or ICD 14 (if present). The pacemaker 80 can be configured to switch to a VAD mode of operation by adjusting at least one control parameter for controlling the delivery of cardiac pacing pulses during the VAD mode.

[0049] exist Figure 1A and 1B8 is shown implanted in the right ventricle of heart 8, with VAD 100 coupled to the left ventricle. In other examples, intracardiac pacemaker 80 may be implanted in a different cardiac chamber, for example, the left ventricle, particularly when VAD 100 is coupled to the right ventricle rather than the left ventricle. As described below, switching to VAD mode by a pacemaker such as pacemaker 80 may include increasing the use of ATP therapy and / or enabling, disabling, or otherwise adjusting ventricular pacing in response to detecting a ventricular tachyarrhythmia. Pacemaker 80 may generally correspond to the intracardiac pacemaker disclosed in U.S. Pat. No. 9,808,637 (Sharma et al.).

[0050] Figure 2 is a conceptual diagram of a patient 12 implanted with an IMD system 200 including an ICD 214 and a VAD 100 according to another example. In this example, the ICD 214 is coupled to a transvenous lead carrying electrodes for sensing cardiac electrical signals and delivering electrical stimulation pulses to the heart 8 for cardiac rhythm management, such as bradycardia pacing, post-shock pacing, ATP, CRT, and / or CV / DF shocks as examples. Figure 2 2 is shown implanted in the right pectoralis muscle location; however, it should be appreciated that the ICD 214 may be implanted in the left pectoralis muscle location, particularly when the ICD 214 includes cardioversion and defibrillation capabilities using the housing 215 as electrodes.

[0051] The ICD 214 is shown as a dual chamber device for sensing and delivering therapy in the atrial chamber 202 and the ventricular chamber 204 of the heart 8. As such, the ICD 214 includes a connector assembly 217 having two connector apertures for receiving proximal connectors for a right atrial (RA) lead 210 and a right ventricular (RV) lead 220. In other examples, the ICD 214 may be a single chamber device, e.g., connectable only to the RV lead 220, or a multi-chamber device including a third connector aperture, e.g., for receiving a coronary sinus lead, to enable the ICD 214 to sense left ventricular signals and deliver electrical stimulation pulses to the LV 203.

[0052] RA lead 210 may carry a distal tip electrode 216 and a ring electrode 218 spaced proximally from tip electrode 216 to deliver pacing pulses to RA 202 and obtain atrial electrical signals to generate atrial intracardiac electrogram (EGM) signals by ICD 214. RV lead 220 may carry pacing electrodes 228 and sensing electrodes 230 to deliver RV pacing pulses to RV 204 and obtain ventricular electrical signals to generate RV EGM signals by ICD 214. RV lead 220 may also carry RV defibrillation electrode 224 and superior vena cava (SVC) defibrillation electrode 226. Defibrillation electrodes 224 and 226 are shown as coil electrodes spaced proximally from distal pacing electrode 228 and sensing electrode 230.

[0053] ICD housing 215 encloses circuitry, as described below, configured to detect arrhythmias and provide electrical stimulation therapy, such as bradycardia pacing, post-shock pacing, ATP, CRT, and / or CV / DF shock therapy, using electrodes 216, 218, 224, 226, 228, and 230 of transvenous leads 210 and 220. ICD 214 is configured to operate in VAD mode for the purpose of managing arrhythmia monitoring and cardiac electrical stimulation therapy delivery when patient 12 has hemodynamic support provided by VAD 100.

[0054] As combined Figure 1A and 1B As depicted, the VAD 100 includes a blood pump 101 having a pump housing 102 that encloses an internal pump chamber for receiving blood from the left ventricle 203 of the heart 8 through an inflow cannula 104. The pump housing 102 may enclose a rotating impeller motor that drives blood through the internal pump chamber and out of an outflow port 106, through a vascular graft 108, and into the ascending aorta 6. A percutaneous drive wire 120 provides power and control signals to the electromagnetic stator of the motor from an external controller 110 that may be worn by the patient 12. The drive wire 120 may include an outer circumferential sheath 119 constructed of braided polyester or other biocompatible braided or porous material to promote tissue ingrowth at the skin exit site of the percutaneous drive wire 120.

[0055] Figure 3 is a schematic diagram of an ICD 314 that may be co-implanted with the VAD 100 and configured to operate in a VAD mode. Figure 3 The circuit system shown and described in the may correspond to the circuit system included in Figure 1A ICD 14 or Figure 2 The electronic circuit system enclosed in the housing 315 (in Figure 3The ICD 314 (schematically shown as electrodes) contains software, firmware, and hardware that cooperatively monitors cardiac electrical signals generated by the patient's heart, determines when electrical stimulation therapy is needed, and delivers therapy when needed according to programmed therapy delivery algorithms and control parameters. The software, firmware, and hardware are configured to detect tachyarrhythmias and deliver anti-tachyarrhythmia therapy, for example, to detect ventricular tachyarrhythmias and determine when ATP and / or CV / DF shocks are needed. The ICD 314 is coupled to one or more leads carrying electrodes 324, 326, 328, and 330, for example, Figure 1A A cardiovascular external lead such as lead 16 or Figure 2 Transvenous leads, such as leads 210 and 220, are shown for delivering electrical stimulation pulses to the patient's heart and for sensing cardiac electrical signals.

[0056] ICD 314 includes control circuitry 380, memory 382, ​​therapy delivery circuitry 384, sensing circuitry 386, and telemetry circuitry 388. In addition to cardiac electrical signal sensing electrodes coupled to sensing circuitry 386 and therapy delivery circuitry 384, ICD 314 may include patient alarms 394 and / or one or more physiological sensors 396. Power supply 398 provides power to the circuitry of ICD 314, including each of circuits 380, 382, ​​384, 386, 388, 394, and 396, as needed. Power supply 398 may include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. Figure 3 The connections between the power supply 398 and each of the other components 380, 382, ​​384, 386, 388, 394, and 396 can be understood from the overall block diagram, but are not shown for clarity. For example, the power supply 398 can be coupled to one or more charging circuits included in the therapy delivery circuit 384 to charge the holding capacitors included in the therapy delivery circuit 384 that are discharged at appropriate times under the control of the control circuit 380 to generate electrical pulses according to a therapy regimen, such as for bradycardia pacing, CRT, post-shock pacing, ATP, and / or CV / DF shock pulses. The power supply 398 can also be coupled to components of the sensing circuit 386, such as sense amplifiers, analog-to-digital converters, switching circuit systems, etc., telemetry circuits 388, alarms 394, sensors 396, and memory 382 to provide power when needed.

[0057] Figure 3The functional blocks shown in represent the functions contained in an ICD, which is configured to sense cardiac electrical signals and deliver cardiac electrical stimulation therapy, and may include any discrete and / or integrated electronic circuit components that implement analog and / or digital circuits capable of producing the functions possessed by the ICD herein. Individual components may include application-specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated or groups) and memories, combinational logic circuits, state machines or other suitable components or combinations of components that provide the described functions, which execute one or more software or firmware programs. The specific form of software, hardware and / or firmware used to implement the functions disclosed herein will be determined primarily by the specific system architecture used in the ICD and the specific detection and therapy delivery methods used by the ICD. Given the disclosure herein, it is within the capabilities of those skilled in the art to provide software, hardware and / or firmware to accomplish the described functions in the context of any modern IMD system.

[0058] Memory 382 may include any volatile, nonvolatile, magnetic, or electrically non-transitory computer-readable storage medium, such as random access memory (RAM), read-only memory (ROM), nonvolatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, or any other memory device. In addition, memory 382 may include a non-transitory computer-readable medium that stores instructions that, when executed by one or more processing circuits, cause control circuit 380 and / or other ICD components to perform various functions possessed by ICD 314 or those ICD components. The non-transitory computer-readable medium that stores instructions may include any of the media listed above.

[0059] The functions possessed by ICD 314 herein may be embodied as one or more integrated circuits. The description of different features of the circuits is intended to highlight different functional aspects and does not necessarily imply that such circuits must be implemented by separate hardware or software components. Instead, the functions associated with one or more circuits may be performed by separate hardware, firmware, or software components, or may be integrated within common hardware, firmware, or software components. For example, cardiac event sensing and tachyarrhythmia detection operations may be performed in collaboration by sensing circuit 386 and control circuit 380, and may be included in operations implemented in a processor executing instructions stored in memory 382 or in other signal processing circuit systems included in control circuit 380, the operations generating control signals such as blanking intervals and timing intervals and sensing threshold amplitude signals sent from control circuit 380 to sensing circuit 386.

[0060] When the ICD 314 is not co-implanted with the VAD 100, the control circuit 380 controls the ICD 314 to operate in a normal non-VAD operating mode. The non-VAD mode can be a default operating mode enabled in the ICD 314 when the device is manufactured, or a default operating mode otherwise programmed into the ICD 314 at the time of implantation or at a subsequent appointment. When the ICD 314 is co-implanted with the VAD 100, the ICD 314 is converted to operate in the VAD mode. In the VAD mode, one or more therapies delivered by the ICD 314 and considered urgent during the non-VAD mode may be considered less urgent and delayed or denied. The control circuit 380 communicates with the therapy delivery circuit 384 and the sensing circuit 386, for example, via a data bus. Therapy delivery circuitry 384 and sensing circuitry 386 are electrically coupled to electrodes 324, 326, 328, 330 and housing 315, which may act as a common or ground electrode or an active metal can electrode for delivering CV / DF shock pulses or cardiac pacing pulses. Figure 2 In the example ICD 214 , additional atrial electrodes 216 and 218 carried by the transvenous atrial lead 210 may be coupled to the sensing circuit 386 and the therapy delivery circuit 384 .

[0061] The sensing circuit 386 may be selectively coupled to the electrodes 328, 330 and / or the housing 315 to monitor the electrical activity of the patient's heart. The sensing circuit 386 may additionally be selectively coupled to the defibrillation electrodes 324 and / or 326 to be used together or in combination with one or more of the electrodes 328, 330 and / or the housing 315 for a sensing electrode vector. The sensing circuit 386 may be enabled to selectively receive cardiac electrical signals from at least two sensing electrode vectors from the available electrodes 324, 326, 328, 330 and the housing 315. Two cardiac electrical signals from two different sensing electrode vectors may be received simultaneously by the sensing circuit 386. The two sensing electrode vectors may include two different ventricular sensing electrode vectors, each ventricular sensing electrode vector coupled to a corresponding sensing channel 383 and 385. In other instances, when an atrial sensing electrode vector is available, for example, when there is an RA lead 210 carrying an atrial pacing electrode 216 and a sensing electrode 218 (e.g., Figure 2 As shown), one sensing channel 383 can be an atrial sensing channel coupled to an atrial sensing electrode, and one sensing channel 385 can be a ventricular sensing channel coupled to a ventricular sensing electrode.

[0062] The sensing circuit 386 can monitor one or two cardiac electrical signals at a time to sense cardiac electrical events such as a P wave accompanying depolarization of the atrial muscle and / or an R wave accompanying depolarization of the ventricular muscle, and provide a digitized cardiac signal waveform for analysis by the control circuit 380. For example, the sensing circuit 386 can include switching circuitry for selecting which of the electrodes 324, 326, 328, 330 and housing 315 are coupled to the first sensing channel 383 and which are coupled to the second sensing channel 385 of the sensing circuit 386. The switching circuitry can include a switch array, a switch matrix, a multiplexer, or any other type of switching device suitable for selectively coupling components of the sensing circuit 386 to selected electrodes.

[0063] Each sensing channel 383 and 385 can be configured to amplify, filter, and digitize cardiac electrical signals received from selected electrodes coupled to the corresponding sensing channel to improve signal quality for detecting cardiac electrical events, such as R waves, or performing other signal analysis. The cardiac event detection circuit system within the sensing circuit 386 can include one or more sense amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog or digital components. The cardiac event sensing threshold can be automatically adjusted by the sensing circuit 386 under the control of the control circuit 380 based on the timing interval and sensing threshold determined by the control circuit 380, stored in the memory 382, ​​and / or controlled by the hardware, firmware, and / or software of the control circuit 380 and / or the sensing circuit 386.

[0064] After detecting a cardiac electrical signal (e.g., an R wave or a P wave) based on a sensing threshold crossing, the sensing circuit 386 can generate a sensed event signal, such as an R wave sensed event signal, that is transmitted to the control circuit 380. The R wave sensed event signal is also used by the control circuit 380 to determine a ventricular event interval (referred to as an "RR interval" or "RRI") to detect tachyarrhythmias and determine the need for therapy. The ventricular event interval or RRI is the time interval between two consecutive sensed R waves, and can be determined between two consecutive R wave sensed event signals received from the sensing circuit 386. For example, the control circuit 380 may include a timing circuit 390 for determining the RRI between consecutive R wave sensed event signals received from the sensing circuit 386, and controlling various timers and / or counters for controlling the timing of therapy delivery performed by the therapy delivery circuit 384. The timing circuit 390 may additionally set time windows such as morphology template windows, morphology analysis windows, or perform other timing-related functions of the ICD 314, including synchronizing CV / DF shocks or other therapies delivered by the therapy delivery circuit 384 with sensed cardiac events. In VAD mode, shock therapy may be withheld or delayed. The timing circuit 390 may track the duration of VT or VF events for use in determining VT or VF burden and / or maximum VT or VF event times prior to delivering therapy or generating physician and / or patient alarms.

[0065] The tachyarrhythmia detector 392 is configured to analyze the signals received from the sensing circuit 386 to detect tachyarrhythmia events. The tachyarrhythmia detector 392 can be implemented in the control circuit 380 as software, hardware and / or firmware that processes and analyzes the signals received from the sensing circuit 386 to detect VT and / or VF. In some instances, the tachyarrhythmia detector 392 can include a comparator and a counter for counting the RRI determined by the timing circuit 390 that falls into various rate detection zones for determining the ventricular rate, or performing other rate-based or interval-based assessments for detecting and distinguishing VT and VF. For example, the tachyarrhythmia detector 392 can compare the RRI determined by the timing circuit 390 with one or more tachyarrhythmia detection intervals, such as a tachycardia detection interval and a fibrillation detection interval. RRIs that fall within the detection interval are counted by the corresponding VT interval counter or VF interval counter, and in some cases, are counted in a combined VT / VF interval counter included in the tachyarrhythmia detector 392.

[0066] When the VT or VF interval counter reaches a threshold count value, which is referred to as the "number of intervals to be detected" or "NID", a ventricular tachyarrhythmia can be detected by the control circuit 380. The tachyarrhythmia detector 392 can be configured to perform other signal analysis to determine whether other detection criteria are met before detecting VT or VF when the NID is reached. For example, cardiac signal analysis can be performed to determine whether R-wave morphology criteria, event criteria, and noise and oversensing rejection criteria are met in order to determine whether VT / VF detection should be performed or rejected. As disclosed herein, when operating in VAD mode, the tachyarrhythmia detector 392 can use different detection parameter values, e.g., a higher NID, as compared to a normal non-VAD operating mode. When the ICD 314 is operating in VAD mode, the control circuit 380 can reject or delay VT or VF detection. In other examples, when tachyarrhythmia detector 392 detects VT or VF, but ICD 314 is operating in VAD mode, control circuit 380 may withhold or delay therapy delivered by therapy delivery circuit 384. In such cases, VT and VF detection criteria (e.g., NID) may remain the same during VAD mode as in non-VAD mode or may remain different.

[0067] To support additional cardiac signal analysis performed by the tachyarrhythmia detector 392, the sensing circuit 386 can deliver digitized cardiac electrical signals to the control circuit 380. The cardiac electrical signals from the selected sensing channels (e.g., from the first sensing channel 383 and / or the second sensing channel 385) can be passed through filters and amplifiers, provided to a multiplexer, and then converted to multi-bit word digital signals by an analog-to-digital converter, all of which are contained in the sensing circuit 386 to be stored in the memory 382. Additional signal analysis can include morphological analysis of predetermined time periods of the cardiac electrical signal or QRS waveform. The morphological analysis can include waveform template matching, for example, using wavelet transform coefficients to classify heartbeats. In some tachyarrhythmia detection schemes, one or more time periods of the received cardiac electrical signal, for example, two or more three 3-second cardiac signal segments, can be analyzed to determine whether the cardiac signal segment should be classified as a tachyarrhythmia that can be treated by CV / DF shock.

[0068] In some instances, the cardiac electrical signals received from the sensing circuit 386 may be additionally analyzed by the control circuit 380 to monitor the patient's cardiac state during the VAD mode. For example, during a sustained ventricular tachyarrhythmia, the control circuit 380 may be configured to monitor for a worsening or worsening of the cardiac rhythm based on T-wave changes in the ventricular electrical signals, such as T-wave amplitude, polarity, QT interval changes, or to monitor for myocardial ischemia. Acceleration of the ventricular tachyarrhythmia, evidence of myocardial ischemia, or other worsening cardiac conditions indicated by analysis of the cardiac electrical signals may require a delay or withholding of therapy in the VAD mode and / or the generation of a patient and / or physician alarm.

[0069] The therapy delivery circuit 384 includes charging circuitry, one or more charge storage devices, such as one or more high voltage capacitors and / or low voltage capacitors, and switching circuitry that controls when the one or more capacitors are discharged across a selected pacing electrode vector or CV / DF impulse vector. The capacitors may be charged to a programmed pulse amplitude and discharged at a programmed pulse width by the therapy delivery circuit 384 in accordance with control signals received from the control circuit 380. The timing circuit 390 of the control circuit 380 may include various timers or counters that control when ATP or other cardiac pacing pulses are delivered. For example, the timing circuit 390 may include a programmable digital counter set by a microprocessor of the control circuit 380 for controlling basic pacing time intervals associated with various pacing modes or ATP sequences delivered by the ICD 314. The microprocessor of the control circuit 380 may also set the amplitude, pulse width, polarity, or other characteristics of the cardiac pacing pulses that may be based on programmed values ​​stored in the memory 382.

[0070] In response to detecting VT or VF during the normal non-VAD mode, the control circuit 380 can control the therapy delivery circuit 384 to deliver a therapy such as ATP and / or CV / DF therapy. As described herein, the therapy response to VT and / or VF detection in the VAD mode can be modified from the therapy response provided in the non-VAD mode. The therapy can be delivered by initiating the charging of the high-voltage capacitor via the charging circuit, both of which are included in the therapy delivery circuit 384. The charging is controlled by the control circuit 380, which monitors the voltage on the high-voltage capacitor transmitted to the control circuit 380 through the charging control line. When the voltage reaches a predetermined value set by the control circuit 380, a logic signal is generated on the capacitor full line and transmitted to the therapy delivery circuit 384, terminating the charging. Under the control of the timing circuit 390, the CV / DF pulse is delivered to the heart by the output circuit of the therapy delivery circuit 384 through the control bus. The output circuit may include an output capacitor, and the charged high-voltage capacitor is discharged through the output capacitor through a switching circuit system such as an H-bridge, and the output circuit determines the electrode and pulse waveform used to deliver the cardioversion or defibrillation pulse. In some examples, a high voltage therapy circuit configured to deliver CV / DF shock pulses can be controlled by control circuit 380 to deliver pacing pulses, for example, for delivering ATP or post-shock pacing pulses. In other examples, therapy delivery circuit 384 can include a low voltage therapy circuit for generating and delivering relatively low voltage pacing pulses for various pacing needs.

[0071] The control parameters utilized by control circuit 380 for detecting arrhythmias and controlling therapy delivery may be programmed into memory 382 via telemetry circuit 388. Telemetry circuit 388 may include communication with external device 40 ( Figure 1A 380). Under the control of control circuit 380, telemetry circuit 388 may receive downlink telemetry from external device 40 and send uplink telemetry to the external device. ICD 314 may receive VAD mode commands from external programmer 40 via telemetry circuit 388.

[0072] The telemetry circuit 388 can be used to transmit communication signals to another medical device (such as VAD 100) implanted in the patient 12 and receive communication signals from another medical device implanted in the patient. Although other communication technologies can be used, the VAD 100 and the ICD 314 can be configured to communicate via wireless RF communication. Before enabling the VAD operating mode of the ICD 314, the ICD 314 can be configured to confirm the presence of the VAD 100 by, for example, wireless communication with an external controller 110. The ICD 314 can be configured to transmit a VT or VF detection signal to the VAD controller 110. The VAD 100 can adjust the drive signal to the pump 101 in response to VT or VF detection to change the pump speed and flow rate. In some instances, the pump speed can be reduced to prevent aspiration events. In other instances, the pump speed can be increased to increase the flow rate to provide increased hemodynamic support.

[0073] In some examples, the ICD 314 may include an alarm circuit 394. The alarm circuit 394 may be configured to generate an audible alarm signal under the control of the control circuit 380 when an alarm condition is detected or an alarm criterion is met. As described below, during the VAD operating mode, the ICD 314 may detect VT or VF, but deny or delay CV / DF shocks, limit the number of shock attempts to terminate VT or VF, and / or increase the use of ATP in terminating a detected VT or VF event, compared to a normal non-VAD operating mode. The control circuit 380 may be configured to control the alarm circuit 394 to notify the patient and / or caregiver of a detected tachyarrhythmia, notify the patient of a scheduled but delayed shock therapy, notify the patient to manually initiate shock therapy, and / or contact his / her clinician or seek medical attention. In other examples, the control circuit 380 may be configured to generate an alarm by controlling the telemetry circuit 388 to transmit an alarm signal to an external device (e.g., an external programmer 40). External programmer 40 may be a home monitoring device coupled to a patient care database and network so that the patient's clinician is notified of alarms and can manually schedule shock therapy and / or schedule a follow-up visit for the patient when needed from a remote location through the patient care network.

[0074] In some examples, the ICD 314 includes one or more physiological sensors 396 for monitoring various physiological signals in addition to the one or more cardiac electrical signals received by the sensing circuit 386. As examples, the one or more sensors 396 may include an accelerometer for monitoring patient activity and / or posture; a temperature sensor for monitoring patient temperature; an acoustic sensor for monitoring heart sounds or respiration; an impedance sensor for monitoring chest impedance; an oxygen sensor, such as an optical sensor, for monitoring tissue or blood oxygen saturation; and / or a pressure sensor for monitoring blood pressure. When switching from a normal non-VAD operating mode to a VAD operating mode, the ICD 314 may be configured to enable or adjust monitoring of one or more physiological signals received from the sensor 396 for detecting changes in the patient's physiological condition during the VAD mode. Detection of a change in a physiological condition may cause the control circuit 380 to control the alarm 394 and / or cause the telemetry circuit 388 to generate / transmit an alarm signal and / or control the therapy delivery circuit to schedule a withheld or delayed therapy.

[0075] Figure 4 yes Figure 1A and 1B 1 is a functional block diagram of an example configuration of a pacemaker 80 shown in . The pacemaker 80 includes a power supply 91, a pulse generator 92, a sensing circuit 94, a control circuit 96, a memory 97, and a telemetry circuit 98. The functions possessed by the pacemaker 100 (or ICD 14) herein may be embodied as one or more processors, controllers, hardware, firmware, software, or any combination thereof. The power supply 91 provides power to each of the other circuits and components of the pacemaker 80 when necessary. The power supply 91 may include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. For clarity, the connections between the power supply 91 and the other pacemaker circuits and components are not shown in FIG. Figure 4 Shown in.

[0076] Pulse generator 92 generates electrical stimulation pulses that are delivered to cardiac tissue via electrodes 84 and 86. Electrodes 84 and 86 may be, for example, Figure 1A and 1B 84 and 86, but one or both of the electrodes 84 and 86 may alternatively be carried by an insulated electrical conductor extending away from the pacemaker housing. Pulse generator 92 may include one or more low voltage capacitors and charging circuitry to charge the one or more capacitors to a programmed pacing pulse voltage under the control of control circuitry 96. At the appropriate time, as controlled by control circuitry 96, the capacitors are coupled to electrodes 84 and 86 to discharge the capacitor voltage and thereby deliver a pacing pulse.

[0077] The control circuit 96 controls the pulse generator 92 to deliver pacing pulses in response to the expiration of the escape interval according to programmed therapy control parameters stored in the memory 97. The pacing timing and control circuitry included in the control circuit 96 may include an escape interval timer or counter set to the escape interval for controlling the timing of pacing pulses relative to a paced or sensed event (e.g., an R wave). When the escape interval expires, a pacing pulse will be delivered. If a cardiac event is sensed by the sensing circuit 94 during the escape interval, the scheduled pacing pulses may be inhibited and the escape interval may be reset to a new time interval. In some instances, the pacemaker 80 delivers ventricular pacing during VAD mode to provide pacing support to mitigate the effects of heart failure and promote adequate filling of the blood pump 101.

[0078] In response to detecting a ventricular tachyarrhythmia, for example, using the RRI-based detection criteria described in U.S. Pat. No. 9,808,637 referenced above, the control circuit 96 controls the pulse generator 92 to deliver one or more ATP pulse sequences according to a programmed therapy regimen. The ATP sequence may include bursts, ramps, bursts and ramps, or other ATP pulse patterns. For example, an ATP burst sequence may be delivered comprising 6 to 10 pacing pulses delivered at a pacing pulse interval that is shorter than up to 97% of the detected RRI. The amplitude of the ATP pulse may be set to a safety margin above a previously determined pacing capture threshold that is expected to capture the ventricle with a high degree of certainty, or it may be set to a nominal amplitude, for example, up to 5 volts. For example, a typical ATP therapy may be a burst of 8 pulses delivered at 88% of the detected RRI cycle length, with each pulse having an amplitude of 5 volts. If VT is redetected, another ATP pulse sequence may be delivered, for example, at an interval shorter than the first sequence. As described below in conjunction with Figure 6 and 7 As described, the ATP control parameters can be adjusted in the VAD operating mode.

[0079] Sensing circuit 94 receives cardiac electrical signals generated across electrodes 84 and 86. A cardiac event can be sensed by sensing circuit 94 when the cardiac electrical signals exceed a sensing threshold, which can be an automatically adjusted sensing threshold. In response to exceeding the sensing threshold, sensing circuit 94 transmits the sensed event signal to control circuit 96 for controlling the timing of pacing pulses. Control circuit 96 receives the R-wave sensed event signal from sensing circuit 94 and determines the RRI as the interval occurring between consecutive R-wave sensed event signals. Rapid arrhythmia detection criteria can be applied to the determined RRI based on an implemented detection algorithm to detect ventricular tachyarrhythmias. During the VAD operating mode, control parameters for controlling rapid arrhythmia detection can be adjusted.

[0080] The memory 97 may contain computer readable instructions that, when executed by the control circuit 96, cause the control circuit 96 to perform various functions possessed by the pacemaker 80. The computer readable instructions may be encoded within the memory 97. The memory 97 may contain any non-transitory computer readable storage medium, including 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 other digital media. The memory 97 stores timing intervals, counters, or other data used by the control circuit 96 to control the delivery of pacing pulses by the pulse generator 92. The memory 97 may store control parameters adjusted for controlling pacemaker functions during the VAD mode.

[0081] The telemetry circuit 98 includes a transceiver and antenna for transmitting and receiving data from the external device 40 via a radio frequency (RF) communication link as described above. The pacemaker 80 can receive pacing and sensing control parameters through the telemetry circuit 98 and store the control parameter values ​​in the memory 97 for access by the control circuit 96. ATP therapy parameters such as ATP type (e.g., burst, ramp, burst plus ramp, etc.), number of pulses, number of ATP trains, etc., can be received by the telemetry circuit 98 from the external device 40.

[0082] A VAD mode command may be received by telemetry circuitry 98 from external programmer 40 to switch pacemaker 80 to VAD mode. A normal non-VAD mode command may be received by telemetry circuitry 98 from external programmer 40 to switch pacemaker 80 back to normal non-VAD mode, e.g., if the VAD is removed. In some instances, pacemaker 80 may be configured to receive a notification signal from ICD 14 or VAD 100 via telemetry circuitry 98 to indicate the presence of VAD 100 and / or to periodically confirm the presence of VAD 100. Upon receiving an initial notification or command indicating the presence of VAD 100, pacemaker 80 may be configured to adjust ventricular tachyarrhythmia detection parameters, pacing therapy control parameters, alarm control parameters, and / or monitoring parameters as described below in conjunction with the accompanying flow charts.

[0083] The pacemaker 80 can transmit data, such as cardiac electrical signal data, and in particular signal data associated with a detected ventricular tachyarrhythmia event, to the external device 40. The transmitted data can be reviewed by a clinician or technician for use in monitoring the occurrence of sustained ventricular tachyarrhythmia events, programming tachyarrhythmia detection parameters, and programming pacing therapy delivered by the pacemaker 80. In instances where the pacemaker 80 is co-implanted with the ICD 14, the pacemaker 80 can transmit a signal to the ICD 14 via the telemetry circuit 98 to confirm tachyarrhythmia detection and / or ATP delivery. In other instances, the pacemaker 80 can signal the ICD 14 that a ventricular tachyarrhythmia has been detected and / or that ATP therapy is about to be performed, is being delivered, or has been completed.

[0084] Figure 5 4 is a flowchart 400 of a method performed by a cardiac rhythm management device according to one example. The methods depicted in flowchart 400 and other flowcharts presented herein are primarily described with reference to ICD 314. However, it should be understood that these methods or aspects of these methods may be performed by an ICD, a pacemaker, or other cardiac rhythm management device (such as pacemaker 80 as an example).

[0085] At box 401, the ICD 314 may be initially configured to be in a non-VAD mode of operation or a "normal" mode of operation. The ICD 314 may be implanted in the patient prior to implantation of the VAD 100 and may be operated in a normal, non-VAD mode according to default and user programmable control parameters and algorithms to detect arrhythmias and automatically deliver electrical stimulation therapy to treat the arrhythmia when needed. In other instances, the ICD 314 may be implanted with the VAD 100 and then implanted thereafter. In these cases, the ICD 314 may be initially configured to be in a normal, non-VAD mode of operation at box 401 when the device is manufactured, but may be programmed to switch to a VAD mode if co-implanted with the VAD 100.

[0086] At block 402, the ICD 314 receives a VAD mode command from another medical device. The other device may be an external programmer (e.g., Figure 1A ) or an external controller of the VAD 100 (e.g., Figure 1A100). The VAD command indicates that the VAD is co-implanted with the ICD 314 in the patient. The control circuit 380 may receive the VAD command indicating the presence of the co-implanted VAD 100 via the telemetry circuit 388. In response to receiving the VAD command, the control circuit 380 switches from the normal non-VAD operating mode to the VAD mode by automatically adjusting one or more control parameters for controlling the operation of the ICD 314 during the VAD mode. The one or more control parameters may include tachyarrhythmia detection parameters, therapy control parameters, criteria for generating an alarm, and / or control parameters for monitoring cardiac electrical signals received by the sensing circuit 386 and / or one or more physiological sensor signals generated by the sensor 396 for detecting changes in the patient's physiological condition.

[0087] In some instances, at box 404, the ICD 314 switches from a normal non-VAD operating mode to a VAD operating mode by adjusting one or more tachyarrhythmia detection control parameters. As an example, the tachyarrhythmia detection control parameters may be adjusted by reducing the VT and / or VF interval range and / or increasing the VT and / or VF NID. The adjustment of the detection control parameters may increase the ventricular rate threshold (e.g., by lowering the RRI threshold detected as a VT or VF interval), thereby requiring the slowest tachyarrhythmia detected in the VAD mode to be faster than the slowest tachyarrhythmia detectable in the non-VAD mode. In this way, since therapy delivery may not be critical when the patient is supported by the VAD 100, a relatively slow VT may not be detected. The adjustment of the detection control parameters may include delayed detection. The minimum time required to detect a relatively fast VT or VF may be increased by increasing the NID and / or increasing the number of cardiac signal time periods required to be classified as VT or VF, thereby allowing more time for spontaneous termination of tachyarrhythmia events. Tachyarrhythmias may need to persist for a longer period of time before detection occurs compared to normal non-VAD mode.

[0088] In some instances, detection control parameters are adjusted at box 404 to enable detection of VT or VF for a sustained period of time when anti-tachyarrhythmia therapy is withheld. For example, a redetection algorithm may be performed at predetermined time intervals after an initial VT or VF detection and continue until VT or VF terminates spontaneously and / or therapy is delivered and the rhythm is terminated. In other instances, once an initial detection is performed, if therapy is not delivered, continuous redetection of VT or VF events based on a beat-to-beat analysis of one or more cardiac electrical signals received by the sensing circuit 386 or other cardiac signal segment-based analysis may still be ongoing. In this way, based on intermittent or continuous redetection of untreated (or unsuccessfully treated) VT or VF events, VT or VF events can be detected as persistent VT or VF events lasting for several minutes, hours, or even days.

[0089] At box 406, the control circuit 380 can adjust patient and / or clinician alarm control parameters. For example, as described below, automatic therapy can be disabled in VAD mode. In this case, an alarm can be generated by the control circuit 380 in response to detecting a VT or VF event, for which automatic therapy would normally be immediately scheduled during the normal non-VAD operating mode of the ICD 314. The alarm can include a patient alarm to enable the patient to manually schedule therapy or seek medical attention. The alarm can include a physician alarm that is transmitted to the patient's physician so that the physician or medical center can contact the patient for follow-up. By generating an alarm, CV / DF shock therapy can be scheduled in a clinical environment to reduce anxiety and the risk of harm to the patient.

[0090] In other instances, the alarm control parameters may include a threshold duration that enables patient and / or physician alarms to be generated in response to detection of a sustained tachyarrhythmia event, a deterioration of the detection tachyarrhythmia event (e.g., acceleration or deterioration to a more severe tachyarrhythmia type) and / or a failed therapy attempt. In some cases, an alarm enabled during a normal non-VAD operating mode may be disabled. For example, a patient alarm about tachyarrhythmia detection may be disabled, but a clinician alarm may be enabled to allow a clinician to select a course of action without causing excessive patient anxiety. Thus, adjusting the alarm control parameters upon receiving a VAD mode command at box 406 may include enabling, adjusting and / or disabling an alarm automatically generated during a normal non-VAD operating mode and / or enabling a new alarm that is unavailable or unused during a non-VAD operating mode. As an example, a patient or physician alarm indicating that a shock VT or VF rhythm detection has been performed may be enabled during a VAD mode, but an automatic therapy is disabled, but such an alarm is unavailable during a non-VAD operating mode.

[0091] At box 410, the control circuit 380 can respond to the VAD mode command by automatically adjusting the therapy delivery control parameters. In some instances, automatic therapy is disabled in VAD mode. In this way, CV / DF shocks are not unexpectedly delivered to the patient because the VAD 100 can fully support the patient hemodynamically. When automatic therapy is disabled, the patient or clinician can manually schedule therapy for a specified time. For example, an alarm can be generated based on the adjusted alarm control parameters set at box 406 to notify the clinician or patient that VT or VF is being detected. Using the external programmer 40, the user can enter the time of day to deliver shock therapy or manually select to deliver shock therapy immediately. For example, the shock therapy can be scheduled to occur later in the day or remain unscheduled, but if the patient develops symptoms, the patient or caregiver may be able to schedule therapy immediately. CV / DF shocks can be manually scheduled by the user so that if the VT or VF event continues until the scheduled CV / DF shock delivery time, one or more CV / DF shocks can be delivered. For example, a user can manually schedule CV / DF shocks to occur only at night when the patient is expected to be sleeping, e.g., when the risk of injury from a fall is reduced.

[0092] In some cases, at block 410, some automatic therapies are disabled in VAD mode, but other therapies may remain enabled or even scheduled for earlier and / or more frequent delivery. For example, in response to VT or VF detection, automatic CV / DF shocks may be disabled, but ATP may remain enabled. The maximum number of ATP attempts may be increased and / or a more aggressive or different type of ATP therapy may be scheduled for progression.

[0093] In other instances, automatic therapy (such as CV / DF shock therapy) can remain enabled in VAD mode, but be scheduled to occur after a time delay from VT / VF detection. The control circuit 380 can automatically schedule CV / DF shocks to occur only at one or more specified times of the day, and can limit the maximum number of shock attempts per day. For example, the control circuit 380 can schedule CV / DF shocks to occur only between 3:00am and 4:00am or another default or user-specified time, and can schedule as few as one shock every twenty-four hours. In this way, therapy can still be automatically scheduled in response to detection of a VT or VF rhythm, but the CV / DF shock is delayed until the patient is expected to fall asleep and the risk of injury is minimized. Clinician and / or patient alarms can be enabled at box 406 to warn clinicians and / or patients of scheduled pending therapy.

[0094] At box 412, the control circuit 380 may adjust one or more patient monitoring parameters. During VAD mode, if the VAD 100 does not provide adequate hemodynamic support, the patient may experience worsening of a tachyarrhythmia or the onset of symptoms. For example, if the flow input from the left ventricle during VT or VF is too low, the VAD 100 may experience a low flow or aspiration event. Thus, additional patient monitoring algorithms may be enabled during VAD mode, particularly when VT or VF therapy is withheld or delayed. Continuous monitoring of the cardiac rhythm may be enabled to detect a rhythm that may be worsening, and therapy that may be delayed or withheld may be scheduled to terminate the worsening rhythm. Other monitoring of physiological signals or patient condition may be enabled or adjusted during VAD mode to detect indications that therapy is needed. For example, monitoring of myocardial ischemia based on T-wave changes, monitoring of relative decreases in oxygen saturation in the blood or tissue using an oxygen sensor, monitoring of respiratory changes using an acoustic sensor or an impedance sensor, monitoring of body temperature changes using a temperature sensor, and / or monitoring of patient activity and / or patient posture using an accelerometer can be performed in order to detect possible deterioration in the patient's condition that may require an alert (to the patient and / or clinician) and / or more rapid delivery of therapy.

[0095] At block 414, control circuit 380 controls operation of ICD 314 in the VAD mode based on at least one adjustment made to a control parameter in at least one of blocks 404, 406, 410, and 412. The adjustment to the control parameter may include automatic adjustments made in response to the VAD mode command and may include manual adjustments to the control parameter programmed by a user using external programmer 40. Although Figure 5 Adjustments to detection parameters (box 404), alarm parameters (406), therapy parameters (410), and monitoring parameters (412) are shown, but it should be understood that switching to VAD mode does not require adjustments to be made at all of boxes 404 to 412. At least one control parameter is adjusted at one box 404 to 412, and one or more parameters may be adjusted at one or more of boxes 404 to 412 to switch to VAD mode.

[0096] At block 416, the ICD 314 may determine that the VAD mode should be terminated by restoring the normal operating parameters and switch to the non-VAD normal operating mode at block 418. In some instances, once the VAD mode is enabled, the VAD mode becomes a "permanent" operating mode for the ICD 314, in that the control circuit 380 may only switch back to a set of control parameters used during the normal non-VAD operating mode in response to receiving a user command from another device. The ICD 314 may not be configured to automatically switch from the VAD mode back to the normal non-VAD mode without receiving a command from another device. If the ICD 314 receives a "normal" command at block 416, such as from an external programmer 40, indicating that the VAD is no longer co-implanted with the ICD 314 or that the VAD mode should be disabled, the control circuit 380 may respond by switching to the normal non-VAD operating mode by restoring the most recently used non-VAD mode operating control parameters at block 418.

[0097] In other examples, the ICD 314 may determine at block 416 that the VAD mode of operation should be terminated due to the absence of a VAD communication signal for a predetermined time interval. For example, the VAD 100 may be configured to periodically (e.g., daily, weekly, or monthly) transmit a notification signal to the ICD 314 to confirm the presence and functionality of the VAD 100. The VAD 100 may transmit the periodic notification signal by pinging the ICD 314 or in response to a periodic request signal transmitted from the ICD 314 to the VAD 100. If a periodic notification signal is not received from the VAD 100, the ICD 314 may determine that the VAD mode of operation should be terminated at block 416 and restore normal non-VAD mode of operation parameters at block 418.

[0098] Figure 6500 is a flow chart of a method performed by an ICD 314 operating in a VAD mode according to an example. After switching to the VAD mode of operation, the control circuit 380 can detect a ventricular tachyarrhythmia (VT or VF) at box 502. As in the normal non-VAD mode of operation, the detection of VT or VF can be based on RRI and / or cardiac electrical signal morphology analysis. However, in some cases, the detection control parameters can be adjusted in the VAD mode to be different from the detection control parameters in the normal non-VAD mode of operation. For example, the NID or threshold number of VT or VF interval counts required to detect VT or VF can be increased compared to the normal non-VAD mode of operation, the maximum RRI counted as a VT interval or as a VF interval can be reduced, or different other thresholds or criteria can be defined for VT / VF detection during the VAD mode. In some examples, the VT / VF detection parameters can be adjusted so that the detection sensitivity is reduced or it takes longer to reach the detection criteria. In other examples, the tachyarrhythmia detection control parameters can be unchanged compared to the normal VAD mode of operation.

[0099] After VF or VF is detected, the control circuit 380 can control the therapy delivery circuit to deliver ATP according to the ATP therapy parameters programmed in the VAD mode. For example, ATP can be used after all VT or VF detections, and / or the maximum number of ATP therapy attempts can be greater than the number of attempts during the non-VAD operating mode. If the detected VT or VF cannot be successfully terminated, ATP can be repeated at predetermined time intervals or a predetermined number of times per day as long as VT or VF can still be detected. In some instances, the control circuit 380 can monitor the heart rhythm to detect a slowing, increased regularity, or other changes in the detected tachyarrhythmia, and control the therapy delivery circuit 384 to deliver ATP in response to detecting changes in the tachyarrhythmia. In other instances, the ATP control parameters may remain unchanged compared to the non-VAD operating mode. ATP can be programmed to be delivered as the first therapy attempt for VT and / or VF.

[0100] At box 506, the control circuit 380 withholds automatic CV / DF shocks that would be delivered in response to VT or VF detection during the normal non-VAD operating mode (and any delivered ATP cannot terminate VT or VF). At box 508, the control circuit 380 can control the telemetry circuit 388 and / or the alarm circuit 394 to generate an alarm to notify the clinician and / or patient that shock therapy is being withheld and that VT or VF that can normally be treated by shock therapy has been detected (in non-VAD mode). At box 510, the control circuit 380 can continuously (beat by beat) or periodically determine whether the VT or VF detection criteria are still met. For example, after a predetermined time interval or number of RRIs, the detection criteria used for initial VT or VF detection or different redetection criteria can be applied to the RRI and / or cardiac signal morphology analysis to determine whether the VT or VF event is persistent. If persistent, the control circuit 380 can store the cardiac signal segments in the memory 382 at box 511 to provide the clinician with a historical record of the persistent event. As long as the event is still detected, the cardiac signal segment can be stored periodically at box 511, and it may not be stored every time the event is re-detected. In some examples, ATP can be attempted periodically during sustained VT or VF, and the control circuit 380 can determine whether VT or VF is still detected after each ATP attempt.

[0101] The pulse therapy withheld at box 506 when VT / VF is detected can be scheduled to occur at a predetermined time of the day, for example, during the night or when the patient is expected to fall asleep, which may be a programmable time of the day. In other examples, the pulse therapy withheld at box 506 can be delivered after a predetermined maximum VT or VF event duration is reached. For example, a VT or VF event of up to one hour, up to four hours, up to eight hours, up to twelve hours, or up to 24 hours can be detected. The control circuit 380 determines at box 512 whether the maximum delay of the pulse therapy or the specified time of the day has been reached. If the withheld shock is scheduled to occur at a specified time of the day or after a predetermined delay (e.g., a specified maximum event duration), the control circuit 380 can verify that VT or VF is still being detected and then deliver the delayed shock at box 514. In some cases, the patient or clinician can manually schedule the withheld shock at box 506 using an external programmer 40. Upon receipt of the "shock now" command, the control circuit 380 controls the therapy delivery circuit 384 to deliver the rejected shock at block 514 after verifying that a VT or VF event is still being detected.

[0102] The shock may be delivered at a predetermined time of day after a predetermined time delay at box 514, or in response to a manually entered shock command using the same shock pulse parameters (e.g., shock energy and pulse waveform) as the pulse parameters programmed for use during the normal, non-VAD operating mode. In other examples, the control parameters defining the shock pulse energy and waveform may be programmed differently during the VAD mode than during the normal, non-VAD mode. If the shock therapy is successful, the control circuit 380 no longer detects a VT or VF event at box 510, and returns to box 502 to continue monitoring the cardiac electrical signals to detect VT / VF according to the VAD operating mode.

[0103] In some instances, at box 516, the control circuit 380 can determine whether a threshold VT or VF burden has been reached. The threshold VT / VF burden can be a total time interval threshold during which a patient can be determined to be in a sustained VT or VF event based on continuous (beat-to-beat) or intermittent but continuous VT / VF redetection. In other instances, the VT / VF burden threshold can be reached when the total duration of one or more VT / VF events reaches a time interval threshold. In still other instances, a maximum number of therapy attempts can be reached if a threshold number of ATP attempts and / or CV / DF shocks have been delivered without terminating the VT or VF event. If the threshold VT / VF burden or the maximum number of therapy attempts is reached, an alarm can be generated at box 508. The alarm can notify a medical professional and / or patient to indicate that medical intervention may be required.

[0104] Figure 7 600 of an ICD operation during VAD mode according to another example. At box 602, the ICD 314 is programmed to operate in VAD mode. As described above, the operating control parameters are automatically and user-programmably adjusted by the control circuit 380 to switch to VAD mode. In response to receiving the VAD mode command, the control circuit 380 may also automatically adjust one or more pacing therapies at box 604. For example, if the ICD 314 is configured to provide CRT using a coronary sinus lead to deliver left ventricular pacing, the left ventricular pacing feature may be disabled at box 604. In other examples, RV pacing may be enabled at box 604. In the presence of VAD 100, the RV pacing function may be enabled to support RV function and mitigate RV malfunction. In the presence of VAD 100, dual chamber or atrial pacing mode may be enabled to provide pacing support. At block 604 , a pacing mode that is programmed or enabled during a normal, non-VAD mode may be disabled or adjusted to a different pacing mode during a VAD mode.

[0105] When VT or VF is detected at box 606 during VAD mode, the automatic shock that would be delivered during normal non-VAD mode can be denied at box 608. At box 610, the control circuit 380 can enable the monitoring function to monitor one or more conditions of the patient who is not immediately treated by delivering shock therapy during the detection of VT or VF. As described above, the ICD 314 can include one or more physiological sensors for generating signals related to the patient's physiological condition. The cardiac electrical signals and / or one or more physiological sensor signals can be monitored to detect a worsening condition of the patient. For example, a worsening of the patient's heart rhythm (e.g., an acceleration of the VT rate) and / or a worsening of the hemodynamic condition can be detected by enabling monitoring at box 610.

[0106] As described above, when VT or VF is detected, an alarm can be generated at box 612. In some instances, the clinician can be warned without warning the patient. If a VT or VF event is still detected at box 614, the control circuit 380 can determine whether the event is changing, for example, in terms of rate and / or regularity, by analyzing one or more cardiac electrical signals received from the sensing circuit 386 at box 616. For example, after the initial VT or VF detection, the RRI can be continuously monitored beat by beat or intermittently to detect a reduction in the RRI, which indicates that the rapid arrhythmia is accelerating. For example, an accelerated rhythm can be detected based on a shorter median RRI since the initial detection. The median RRI can be determined from the most recent predetermined number of RRIs, for example, the most recent 12 to 18 RRIs. If an accelerated rhythm is detected at box 616, the control circuit 380 can control the therapy delivery circuit 384 at box 618 to deliver ATP.

[0107] In other instances, ATP can be delivered in response to a rate deceleration detected based on an increased median RRI. In still other instances, the RRI variability over a predetermined number of RRIs can be determined, for example, by determining the difference between paired RRIs or the difference between each RRI and the median RRI. If a change in RRI variability is detected, ATP can be delivered. As long as VT or VF is still detected, ATP can be delivered at box 618 in response to a change in the detected VT or VF event, the change indicating acceleration, deceleration, regularity change (e.g., smaller variability or larger variability of RRI) or other rhythmic changes. Delivering ATP at box 618 can include one or more attempts to deliver ATP, which can include different ATP therapies, for example, different coupling intervals, different inter-pulse intervals, burst ATP, ramp ATP, etc.

[0108] If a VT or VF event is still detected at box 614 after attempting ATP, and if an accelerated rhythm is not detected at box 616, the control circuit 380 may wait to deliver a shock at box 624 until a shock is manually scheduled by the user or until a specified time of day or a predetermined shock delay expires (the "yes" branch of box 620). If an immediate shock is not manually scheduled and the time for a delayed scheduled shock has not yet been reached (the "no" branch of box 620), the control circuit 380 may determine at box 622 whether other therapy criteria are met. Other criteria for triggering therapy delivery may be applied to the cardiac electrical signal and / or other physiological signals being monitored. For example, an indication of resting patient activity, a non-upright posture, ischemia based on changes in the T wave in the cardiac electrical signal, low oxygen saturation of blood or tissue based on an optical sensor, or other detected conditions may meet a therapy delivery criterion at box 622 such that the control circuit 380 controls the therapy delivery circuit 384 to deliver a shock at box 624. If other therapy criteria are not met at box 622 , the control circuit 380 continues to monitor for VT / VF events at box 614 .

[0109] At any time after ATP, shock, or spontaneous termination, when a VT or VF rhythm is no longer detected at block 614, the control circuit 380 may generate an alarm at block 626 to notify the patient and / or medical personnel that the tachyarrhythmia has terminated. The control circuit 380 returns to block 606 to await the next VT or VF event detection.

[0110] Figure 8 is a conceptual diagram of a user interface 700 that may be generated by processor 52 of external programmer 40 for display to a user on display 54. User interface 700 may include a VAD mode programming window 702 that enables a user to program a VAD mode to "on" or "off." If the "on" button is selected, a verification screen or pop-up window 704 may appear requiring the user to enter authentication data that verifies the presence of the VAD co-implanted in the patient with the ICD being programmed. For example, window 704 may prompt the user to enter a VAD model and / or serial number, a date of VAD implantation, or other information specific to the VAD co-implanted in the patient to verify its presence and the appropriateness of operating the ICD in VAD mode.

[0111] In some examples, once programmed “ON,” VAD mode includes default control parameters for arrhythmia detection, therapy delivery, alarm generation, and / or patient monitoring that are automatically set by control circuitry 380 upon receipt of a VAD mode command from external programmer 40. In other examples, one or more control parameters used by control circuitry 380 to control ICD operation during VAD mode may be programmable by a user interacting with user interface 700.

[0112] exist Figure 8 In the example shown, the user can use the automatic therapy window 710 of the interface 700 to turn automatic shock therapy on or off. If automatic shock therapy is turned off, the user can control the ICD 314 to manually deliver shocks using the manual therapy button 716. For example, as described in conjunction with the flowchart 500, VT or VF can be detected, and if automatic shock is disabled or "off", an alarm can be generated so that the patient (or the clinician during an office visit) can manually control the ICD 314 to deliver shock therapy at a time selected by the patient. This allows the patient to seek help or medical supervision when needed and prepare for shock therapy. Thus, in some examples, when VT or VF is detected and shock therapy is refused, the processor 52 can generate an alarm screen on the interface 700, including the display of the manual therapy button 716.

[0113] If the user enables automatic shock therapy by selecting the "on" button of the automatic therapy window 710, the processor 52 of the external programmer 40 can enable other programmable parameters 712 and 714 of the window 710 for programming. These programmable parameters 712 and 714 allow automatic shocks to be scheduled according to the control parameters programmed by the user during the VAD mode. In the illustrated example, as described above, automatic shock therapy can be refused when VT or VF is detected unless the detected VT or VF continues until the programmed time 712 of the day. The time of the day 712 for shock delivery can be programmed as a start time and an end time entered by the user. For illustration, when the patient is expected to lie in bed and fall asleep, the user can select an automatic shock delivery time interval from 2:00am to 4:00am. If VT or VF is detected outside the programmed time 712 of the day, as long as a tachyarrhythmia event is still detected, shock therapy is refused until the programmed time 712 of the day and delivered during the programmed time 712 of the day. In other instances, as an alternative to or in addition to the programmed time of day 712, the maximum VT / VF event delay interval can be a user-programmable parameter that can be included in the autotherapy window for programming the maximum number of minutes or hours that a detected VT or VF rhythm is allowed to persist before shock therapy is delivered.

[0114] Additionally or alternatively, the automatic therapy window 710 can include a programmable maximum number of shock parameters 714. In the example shown, a maximum number of shocks per twenty-four hour period can be specified. In this way, the user can limit both the time at which a shock can occur and the number of shocks that can be delivered within a given time period during VAD mode. For example, the user can limit the number of shocks to a maximum of one shock per twenty-four hours. If the shock fails to terminate the VT or VF rhythm, the next shock attempt can be made according to the programmed time 712 of the next day. This allows the patient to consult his / her physician before making another shock attempt.

[0115] An extended detection window 720 may be included in the user interface 700 to enable a user to turn extended detection on or off. When off, the VT and VF detection algorithm may be executed according to the same control parameters and detection criteria as used during a normal non-VAD mode. When on, the VT and / or VF detection time may be extended by increasing the NID, increasing the number of cardiac electrical signal time periods required for classification as VT or VF, or otherwise modifying the detection algorithm such that VT or VF is detected relatively late after the onset of the VT or VF event relative to the detection time during a normal non-VAD mode.

[0116] After extended detection is turned on, one or more detection control parameters or criteria can be automatically adjusted. In some instances, some of the detection control parameters used during extended detection can be user programmable parameters. Thus, in response to a user selecting an "on" button of the extended detection window 720, a detection parameter programming window 722 can be displayed on the user interface 700. Examples of programmable extended detection control parameters can include an NID for detecting VT, an NID for detecting VF, the number of cardiac electrical signal time periods required for classification as VT / VF, an interval range of VT and VF (RRI), and / or a minimum time interval for detecting sustained VT or VF.

[0117] The user interface 700 can include an alarm window 730 for enabling or disabling a patient alarm 732. In some cases, the patient alarm can be muted or disabled so that an alarm is only issued to the clinician or medical staff when an alarm condition is met during VAD mode. The alarm condition can be automatically set by the control circuit 380; however, in some instances, the alarm condition can include a user-programmable alarm condition. For example, Figure 8As shown, the alarm window 730 may include: When a VT or VF event has persisted for a programmable threshold time interval (e.g., in minutes or hours), the alarm is enabled. The threshold may be reached in a single persistent event. In other instances, the threshold may be reached by adding the cumulative duration of multiple VT or VF events, in which case the threshold may be referred to as a VT or VF threshold "burden."

[0118] As another example of programmable alarm control parameters in VAD mode, a user can program a failed therapy alarm that will be generated upon redetection of a VT or VF event after a specified number of therapy attempts have been made. Therapy attempts may include only ATP attempts, only shock attempts, or a combination of both (which, in various instances, may each be programmable to generate one or separate alarms). Alarm window 730 may include additional or different programmable alarm control parameters than the specific example shown here, which enable the user to program conditions under which patient alarms are generated (or not generated) and conditions under which clinician alarms are generated (or not generated). Although in Figure 8 704, 722, 742, and 752, it should be understood that the processor 52 can generate a new user interface window or pop-up window within the user interface 700 in response to the user selecting the programmable parameters of the alarm window 730 to enable the user to program various control parameters used by the control circuit 380 for generating alarms. In some examples, for example, the time of day for transmitting an alarm to a clinician and / or patient can be programmable to avoid transmitting an alarm in the middle of the night, for example.

[0119] The user interface 700 may include an extended ATP window 740 that enables the user to program ATP therapy that is more extensively delivered in response to detected VT or VF than during normal non-VAD mode. Since automatic shock therapy can be disabled or delayed during VAD mode, the number of attempts to terminate the detected tachyarrhythmia ATP can be increased. More types of ATP can be tried, for example, ramp, burst, ramp plus burst, etc. The increased number of attempts may include adjusting the coupling interval for synchronizing the leading ATP pulse with the sensed R wave and / or adjusting the ATP time interval between consecutive ATP pulses. Thus, compared to normal non-VAD mode, "extended ATP" may generally refer to increasing ATP use after VT or VF detection. Increasing ATP use may include arranging one or more ATP therapies to occur immediately after VT or VF event detection and / or arranging one or more ATP therapies to occur at a specified time interval, one hour later, eight hours later, etc. delayed from the time of VT or VF detection, so that ATP can be repeated during a sustained VT or VF event. In some examples, extending ATP can include triggering ATP delivery in response to detecting changes in tachyarrhythmia.

[0120] Extended ATP may be programmed by the user through window 740, and control circuit 380 may automatically adjust one or more ATP control parameter settings to increase the number of ATP therapies that will be attempted during a sustained VT or VF event. Figure 8 As indicated, processor 52 may generate a new or pop-up ATP parameter programming window 742 of user interface 700 in response to a user selecting "ON" of extended ATP window 740. Various ATP control parameters, as listed above, may be programmed for control circuitry 380 to control delivery of ATP during VAD mode using window 742.

[0121] The monitoring window 750 is another window that can be included in the user interface 700. By selecting the "on" button of the window 750, additional patient monitoring can be enabled during the VAD mode. The control circuit 380 can automatically adjust one or more monitoring control parameters in response to the programmed monitoring. In some instances, the processor 52 generates a monitoring control parameter programming window 752 in the user interface 700 to enable the user to program the parameters for controlling the patient monitoring performed during the VAD mode, which can be a supplement or substitute for the automatically adjusted monitoring control parameters. In one example, when monitoring is enabled through the window 750, patient temperature monitoring is turned on, and an automatic alarm is generated if the patient's body temperature exceeds a threshold. Patients with implanted VADs are at increased risk of infection, particularly when the VAD contains a percutaneous drive line. Temperature monitoring during the VAD mode can provide an early warning of possible infection. The monitoring window 750 can be used to enable other examples of physiological signals discussed above, such as ischemia monitoring, oxygen saturation monitoring, pressure monitoring, or other physiological signals generated by the sensor 396 included in the ICD 314.

[0122] Although a particular example of user interface 700 is shown, it should be appreciated that various arrangements of one or more interactive windows, screens, tabs, drop-down menus, etc. may be displayed in user interface 700 to enable a user to at least turn on or enable the VAD mode and to enable the user to program various control parameters used by control circuitry 380 during the VAD mode of operation of ICD 314. Once turned on, in some examples, ICD 314 does not automatically revert to the non-VAD mode unless the VAD mode is turned off using user interface 700. Turning off the VAD mode may again require an additional verification step using window 704 to prevent inadvertent disabling of the VAD mode.

[0123] It should be understood that, depending on the example, certain actions or events of any method described herein may be performed in a different order, may be added, merged, or completely excluded (e.g., not all described actions and events are necessary for the method technology). In addition, in some instances, actions or events may be performed simultaneously rather than sequentially, for example, by multithreading, interrupt processing, or multiple processors. In addition, for the purpose of clarity, although certain aspects of the present disclosure are described as being performed by a single circuit or unit, it should be understood that the technology of the present disclosure may be performed by a combination of units or circuits associated with, for example, a medical device.

[0124] In one or more instances, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored in the form of one or more instructions or codes on a computer-readable medium and may be performed by a hardware-based processing unit. The computer-readable medium may include a computer-readable storage medium corresponding to a tangible medium such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store the desired program code in the form of instructions or data structures and can be accessed by a computer).

[0125] Instructions may be executed by one or more processors, such as one or more digital signal processors (DSPs), general purpose microprocessors, application specific integrated circuits (ASICs), field programmable logic arrays (FPGAs), or other equivalent integrated or discrete logic circuit systems. Therefore, the term "processor" as used herein may refer to any of the foregoing structures or any other structure suitable for implementing the techniques described herein. Moreover, the techniques may be fully implemented in one or more circuits or logic elements.

[0126] Thus, in the foregoing description, an implantable cardiac rhythm management device has been presented with reference to a specific example, which can be co-implanted with a VAD and can be programmed to operate in a VAD mode. It should be understood that the various aspects disclosed herein can be combined in different combinations other than the specific combinations presented in the drawings. It should be understood that various modifications can be made to the referenced examples without departing from the scope of the present disclosure and the appended claims and examples.

[0127] Example 1. A method performed by an implantable medical device, the method comprising: operating the implantable medical device according to a first mode, the first mode comprising detecting arrhythmias from cardiac electrical signals and automatically delivering electrical stimulation therapy to the patient's heart in response to detecting the arrhythmia, receiving a command from another medical device instructing to co-implant a ventricular assist device with the implantable medical device in the patient's body, and switching from the first operating mode to a second operating mode in response to receiving the command, wherein switching from the first mode to the second mode comprises adjusting at least one control parameter for controlling the electrical stimulation therapy.

[0128] Example 2. The method of Example 1, wherein adjusting the at least one control parameter comprises disabling automatic delivery of the electrical stimulation therapy in response to detecting the arrhythmia during the second operating mode.

[0129] Example 3. The method of any one of Examples 1 to 2, further comprising adjusting the control parameter by scheduling the electrical stimulation therapy to occur at a predetermined time of day in response to detecting the arrhythmia during the second operating mode.

[0130] Example 4. A method according to any one of Examples 1 to 3, wherein automatically delivering the electrical stimulation therapy includes automatically delivering shock therapy in response to detecting a first ventricular tachyarrhythmia event, the method further comprising: detecting a second ventricular tachyarrhythmia event from the cardiac electrical signal after switching to the second mode; and withholding the shock therapy in response to detecting the second ventricular tachyarrhythmia event during the second mode.

[0131] Example 5. A method according to any one of Examples 1 to 4, wherein adjusting the at least one control parameter includes adjusting an anti-tachycardia pacing therapy control parameter.

[0132] Example 6. A method according to any one of Examples 1 to 5, wherein adjusting the at least one control parameter includes adjusting a tachyarrhythmia detection control parameter, wherein the tachyarrhythmia detection control parameter extends the minimum time required to detect a tachyarrhythmia during the second mode compared to the first mode.

[0133] Example 7. The method of any one of examples 1 to 6, wherein switching to the second mode further comprises adjusting criteria for generating an alarm during the second mode.

[0134] Example 8. A method according to any one of Examples 1 to 7, further comprising detecting a tachyarrhythmia from the cardiac electrical signal during the second mode, delaying the electrical stimulation therapy in response to detecting the tachyarrhythmia during the second mode, and generating an alarm indicating that the tachyarrhythmia was detected and the electrical stimulation therapy was delayed.

[0135] Example 9. A method according to any one of Examples 1 to 8, further comprising: operating according to the second mode by detecting a tachyarrhythmia from the cardiac electrical signal, denying automatic delivery of the electrical stimulation therapy in response to detecting the tachyarrhythmia during the second mode, receiving a therapy command for scheduling the electrical stimulation therapy from an external device through a telemetry circuit, and scheduling the electrical stimulation therapy in response to receiving the therapy command.

[0136] Example 10. A method according to any one of Examples 1 to 9, wherein switching to the second mode further includes adjusting a monitoring parameter for detecting a change in a patient condition.

[0137] Example 11. The method of Example 10, further comprising sensing a physiological signal different from the cardiac electrical signal, wherein adjusting the monitoring parameter comprises adjusting a parameter for detecting the patient condition from the physiological signal.

[0138] Example 12. A method according to any one of Examples 10 to 11, wherein sensing the physiological signal includes sensing at least one of a temperature signal, an impedance signal, a pressure signal, an acoustic signal, an accelerometer signal, or an oxygen signal.

[0139] Example 13. A method according to any one of Examples 1 to 12, further comprising detecting ventricular tachyarrhythmia from the cardiac electrical signal and transmitting a tachyarrhythmia detection signal to the ventricular assist device after switching to the second operating mode.

[0140] Example 14. A method according to any one of Examples 1 to 13, wherein adjusting the at least one control parameter includes adjusting a cardiac pacing control parameter.

[0141] Example 15. The method of Example 14, wherein adjusting the cardiac pacing control parameters includes disabling left ventricular pacing.

[0142] Example 16. A method according to any one of Examples 14 to 15, wherein adjusting the cardiac pacing control parameters includes enabling right ventricular pacing.

[0143] Example 17. A method according to any one of Examples 1 to 16, further comprising: receiving a second command indicating that the ventricular assist device is no longer co-implanted with the implantable medical device in the patient's body, and restoring the first operating mode only in response to receiving the second command.

[0144] Example 18. A method according to any one of Examples 1 to 17, further comprising: receiving a periodic signal confirming that the ventricular assist device is co-implanted with the implantable medical device in the patient's body, and restoring the first operating mode in response to not receiving the periodic signal.

[0145] Example 19. A non-transitory computer-readable storage medium comprising a set of instructions that, when executed by a controller of an implantable medical device, cause the device to operate according to a first mode, the first mode comprising detecting an arrhythmia from cardiac electrical signals and automatically delivering electrical stimulation therapy to the patient's heart in response to detecting the arrhythmia, receiving a command from another medical device instructing to co-implant a ventricular assist device with the implantable medical device in the patient's body, and switching from the first operating mode to a second operating mode in response to receiving the command, wherein switching from the first mode to the second mode comprises adjusting at least one control parameter for controlling the electrical stimulation therapy.

[0146] Example 20. A programmer for programming an implantable medical device, the programmer comprising: a display; a telemetry circuit configured to communicate bidirectionally with the implantable medical device; and a processor configured to: generate a user interface on the display, the user interface comprising a VAD mode window for receiving user input for enabling a ventricular assist device (VAD) operating mode of the implantable medical device, and control the telemetry circuit to transmit a VAD operating mode command to the implantable medical device in response to the user input to enable the VAD operating mode.

[0147] Example 21. A programmer according to Example 20, wherein the processor is configured to generate the user interface, the user interface comprising a verification window for receiving user input for verifying the presence of the VAD co-implanted in the patient's body before transmitting the VAD operating mode command.

[0148] Example 22. A programmer according to any of Examples 20 to 21, wherein the processor is configured to generate the user interface, the user interface comprising a therapy window for receiving user input for selecting automatic shock therapy control parameters used by the implantable medical device for controlling shock therapy during a VAD operating mode.

[0149] Example 23. A programmer according to Example 22, wherein the processor is configured to generate the therapy window, the therapy window including at least one of a user input time for delivering automatic therapy and a maximum number of user inputs for automatic therapy within a predetermined time period.

[0150] Example 24. A programmer according to any of Examples 20 to 23, wherein the processor is configured to generate the user interface, the user interface comprising an extended ventricular tachyarrhythmia detection window for receiving user input for controlling ventricular tachyarrhythmia detection for an extended time by the implantable medical device during the VAD operating mode.

[0151] Example 25. A programmer according to any of Examples 20 to 24, wherein the processor is configured to generate the user interface, the user interface comprising an alarm window for receiving standard user input for controlling the generation of alarms used by the implantable medical device during the VAD operating mode.

[0152] Example 26. A programmer according to any of Examples 20 to 25, wherein the processor is configured to generate the user interface, the user interface comprising an anti-tachyarrhythmia pacing window for receiving user input control parameters for controlling anti-tachyarrhythmia control by the implantable medical device during the VAD operating mode.

[0153] Example 27. A programmer according to any of Examples 20 to 26, wherein the processor is configured to generate the user interface, the user interface comprising a monitoring window for receiving user input for monitoring of physiological signals through the implantable medical device during the VAD operating mode.

Claims

1. A medical device comprising: a sensing circuit configured to receive cardiac electrical signals generated by a patient's heart; a therapy delivery circuit configured to generate electrical stimulation therapy for delivery to the heart of the patient; telemetry circuitry configured to receive a command from another medical device instructing to co-implant a ventricular assist device with the medical device in the patient; as well as a control circuit coupled to the sensing circuit, the therapy delivery circuit, and the telemetry circuit and configured to: operating in a first mode, the first mode comprising detecting an arrhythmia from the cardiac electrical signals and controlling the therapy delivery circuitry to automatically deliver the electrical stimulation therapy in response to detecting the arrhythmia; and Switching from operating in the first mode to operating in a second mode in response to receiving the command, wherein switching to the second mode includes adjusting at least one control parameter for controlling the electrical stimulation therapy.

2. The apparatus of claim 1 , wherein the control circuit is configured to adjust the at least one control parameter by one or more of: disabling automatic delivery of the electrical stimulation therapy in response to detecting the arrhythmia during the second mode; scheduling the electrical stimulation therapy to occur at a predetermined time of day in response to detecting the arrhythmia during the second mode; adjusting anti-tachycardia pacing therapy control parameters; and A tachyarrhythmia detection control parameter is adjusted to extend a minimum time required to detect a tachyarrhythmia during the second mode compared to the first mode.

3. The apparatus according to any one of claims 1 to 2, wherein the control circuit is configured to: detecting the arrhythmia as a first ventricular tachyarrhythmia event during the first mode; controlling the therapy delivery circuitry to deliver the electrical stimulation therapy as a shock therapy automatically delivered in response to detecting the first ventricular tachyarrhythmia event; After switching to the second mode, detecting a second ventricular tachyarrhythmia event from the cardiac electrical signal; and The shock therapy is withheld in response to detecting the second ventricular tachyarrhythmia event during the second mode.

4. The apparatus of any one of claims 1 to 2, wherein the control circuit is further configured to switch to the second mode by adjusting criteria for generating an alarm during the second mode.

5. The apparatus according to any one of claims 1 to 2, wherein the control circuit is configured to operate in the second mode by: detecting a tachyarrhythmia from the cardiac electrical signal; delaying the electrical stimulation therapy in response to detecting the tachyarrhythmia; and An alarm is generated indicating that the tachyarrhythmia is detected and the electrical stimulation therapy is delayed.

6. The apparatus of any one of claims 1 to 2, wherein the control circuit is configured to operate in the second mode by: detecting a tachyarrhythmia from the cardiac electrical signal; withholding automatic delivery of the electrical stimulation therapy in response to detecting the tachyarrhythmia during the second mode; receiving, via the telemetry circuit, a therapy command for scheduling the electrical stimulation therapy from an external device; as well as The electrical stimulation therapy is scheduled in response to receiving the therapy command.

7. The apparatus according to any one of claims 1 to 2, wherein the control circuit is further configured to switch to the second mode by adjusting a monitoring parameter used by the control circuit to detect a change in a patient condition.

8. The device of claim 7, further comprising a sensor for sensing a physiological signal different from the cardiac electrical signal, wherein the sensor comprises at least one of a temperature sensor, an impedance sensor, a pressure sensor, an acoustic sensor, an accelerometer, or an oxygen sensor, Wherein the control circuit is configured to adjust the monitoring parameter by adjusting a parameter used to detect the patient condition from the physiological signal.

9. The apparatus according to any one of claims 1 to 2, wherein the control circuit is further configured to: After switching to the second mode, detecting ventricular tachyarrhythmia from the cardiac electrical signal; and The telemetry circuit is controlled to transmit a tachyarrhythmia detection signal to the ventricular assist device.

10. The apparatus of any one of claims 1 to 2, wherein the control circuit is configured to adjust the at least one control parameter by adjusting a cardiac pacing control parameter.

11. The apparatus of claim 10, wherein adjusting the cardiac pacing control parameter comprises one or more of disabling left ventricular pacing and enabling right ventricular pacing.

12. The apparatus according to any one of claims 1 to 2, wherein the control circuit is configured to: receiving a second command indicating that the ventricular assist device is no longer co-implanted with the medical device in the patient; and The first mode is restored only in response to receiving the second command.

13. The apparatus according to any one of claims 1 to 2, wherein the control circuit is configured to: receiving a periodic signal confirming that the ventricular assist device and the medical device are co-implanted in the patient; and The first mode is resumed in response to failure to receive the periodic signal.

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