Medical lead migration detection

Abstract

A medical device is configured to sense one or more electrophysiological signals including a distal vector signal sensed using a distal electrode of a medical electrical lead when the medical electrical lead is connected to the medical device. Based at least on the distal vector signal, the medical device may detect a migration of a medical electrical lead carrying the distal electrode and generate an output in response to detecting the migration of the medical electrical lead.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 585,946, filed September 27, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates in its entirety to medical devices and methods for detecting the migration of implanted medical leads. Background Technology

[0003] Medical devices can sense electrophysiological signals from the heart, brain, nerves, muscles, or other tissues. Such devices can be implantable, wearable, or external, using implantable and / or surface (skin) electrodes to sense these electrophysiological signals. In some cases, such devices can be configured to deliver treatment based on the sensed electrophysiological signals. Medical devices can deliver therapeutic electrical stimulation to the heart, brain, nerves, muscles, or other tissues via one or more electrodes on and / or coupled to one or more medical electrical leads on the medical device. For example, a medical device can be a neurostimulator configured to sense neural signals and deliver electrical stimulation pulses based on the neural signals sensed by the neurostimulator. In other examples, implantable or external pacemakers, cardioverter defibrillators, cardiac monitors, etc., can sense cardiac electrical signals from a patient's heart. A medical device can sense cardiac electrical signals from the chambers of the heart and deliver electrical stimulation therapy to the heart using electrodes carried by medical electrical leads operatively positioned for delivering treatment to the patient's heart.

[0004] For example, a pacemaker or cardioverter-defibrillator can deliver therapeutic electrical stimulation to the heart via electrodes carried by one or more medical electrical leads. The electrical stimulation can include electrical pulses such as pacing pulses and / or cardioverter-defibrillator (CV / DF) shocks. In some cases, the medical device can sense cardiac electrical signals associated with inherent depolarization of the myocardium and control the delivery of stimulation pulses to the heart based on the sensed cardiac electrical signals. Upon detection of abnormal rhythms such as bradycardia, tachycardia, or fibrillation, one or more appropriate electrical stimulation pulses can be delivered to restore or maintain a more normal cardiac rhythm. For example, an implantable cardioverter-defibrillator (ICD) can deliver pacing pulses to a patient's heart upon detection of bradycardia or tachycardia, or deliver a high-voltage cardioverter-defibrillator (CV / DF) shock to the heart upon detection of tachycardia or fibrillation. Summary of the Invention

[0005] Generally, this disclosure relates to medical devices and techniques for sensing electrical signals and detecting migration of medical electrical leads connected to a medical device based on the sensed electrical signals. A medical device operating according to the techniques disclosed herein can be configured to sense at least one electrophysiological signal (e.g., cardiac electrical signals, neural signals, or other electrophysiological signals) that is a distal vector signal sensed using a sensing electrode vector comprising at least one electrode carried by the medical electrical lead. The at least one electrode can be carried at or near the distal end of the medical electrical lead connected to the medical device via a proximal lead connector. Based on the processing and analysis of at least the distal vector signal, the medical device can detect migration of the distal end of the lead.

[0006] In some examples, the medical device is configured to sense both distal and proximal vector signals. The proximal vector signal can be sensed using a proximal sensing electrode vector, which includes an electrode carried by a medical lead that is closer to a more distal electrode (e.g., carried at or near the distal end of the medical lead). The proximal sensing electrode vector does not include a relatively more distal electrode for sensing the distal vector signal. The medical device can be configured to perform analysis of the distal and proximal vector signals to detect migration of the medical lead. The analysis may include detecting a threshold change in the distal vector signal while the proximal vector signal remains relatively unchanged compared to a previous time point. The analysis may include detecting a threshold change in a difference signal determined to be the difference between the distal and proximal vector signals. In the case of a cardiac medical device, the analysis may include detecting changes in cardiac electrical event signals (e.g., P waves and / or R waves) that can be sensed as electrical event signals in both the distal and / or proximal vector signals. This paper further describes various examples of analyses performed using at least the distal vector signal for detecting migration of medical electrical leads.

[0007] In one example, this disclosure provides a medical device system including a housing with a connector block configured to receive at least one medical electrical lead having a distal end and carrying at least a distal electrode. The medical device system may further include a treatment delivery circuit configured to deliver electrical stimulation therapy and a sensing circuit configured to receive one or more electrophysiological signals, including a distal vector signal received via a distal sensing electrode vector including the distal electrode. The medical device system may further include control circuitry in communication with the sensing circuitry and the treatment delivery circuitry. The control circuitry may be configured to control the treatment delivery circuitry to deliver electrical stimulation therapy based on the one or more electrophysiological signals received by the sensing circuitry. The control circuitry may also be configured to detect migration of the medical electrical lead carrying the distal electrode, at least based on the distal vector signal, and to generate an output in response to detecting migration of the medical electrical lead. The medical device system may further include a memory configured to store data corresponding to the generated output.

[0008] In another example, this disclosure provides a method comprising delivering cardiac electrical stimulation therapy and sensing one or more cardiac electrical signals, the one or more cardiac electrical signals including a distal vector signal sensed via a distal sensing electrode vector of a distal electrode including a medical electrical lead. The method may further include detecting migration of the medical electrical lead carrying the distal electrode based at least on the distal vector signal, and generating an output in response to detecting migration of the medical electrical lead. The method may further include storing data corresponding to the output in a medical device memory.

[0009] In yet another example, this disclosure provides a non-transitory computer-readable medium storing a set of instructions that, when executed by control circuitry of a medical device, cause the medical device to sense a distal vector signal via a distal sensing electrode vector including a distal electrode of a medical electrical lead, and to sense a proximal vector signal via a proximal sensing electrode vector including a proximal electrode but not a distal electrode. The proximal electrode is positioned more proximally than the distal electrode, i.e., further away from the distal end of the medical electrical lead. These instructions may also cause the medical device to detect migration of the medical electrical lead based on the distal and proximal vector signals, generate an output in response to detecting migration of the medical electrical lead, and store data corresponding to the output in the medical device's memory.

[0010] This invention is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive interpretation of the devices and methods described in detail in the following drawings and description. Further details of one or more examples are set forth in the following drawings and description. Attached Figure Description

[0011] Figure 1A and Figure 1B This is a conceptual diagram of an example of an ICD system that can be configured to detect lead migration based on the techniques disclosed herein.

[0012] Figures 2A to 2C Is it implanted in a position with Figures 1A to 1B The diagram shows a concept of a patient with an ICD system arranged in different implantation configurations.

[0013] Figure 3 It is based on a conceptual diagram of an example ICD.

[0014] Figure 4 It can be included based on an example. Figure 3 The diagram shows a conceptual representation of the circuitry in the sensing circuit of the ICD.

[0015] Figure 5 This is a conceptual diagram based on some examples of electrophysiological signals that can be sensed and analyzed by medical devices to detect lead migration.

[0016] Figure 6 This is a flowchart illustrating, based on some examples, a method for detecting lead migration that can be performed by a medical device.

[0017] Figure 7 This is a flowchart of a method for detecting lead migration that can be performed by a medical device, according to another example.

[0018] Figures 8A to 8C This is a diagram illustrating the possible changes in the distal vector signal due to lead migration.

[0019] Figure 9 This is an illustration of the changes that may occur in the near-side vector signal due to lead migration. Detailed Implementation

[0020] Generally, this disclosure describes a medical device and technique for analyzing electrophysiological signals sensed using electrodes carried by implantable medical electrical leads to detect the migration of the medical electrical leads. The medical electrical leads can be used to monitor electrophysiological signals and / or deliver electrical stimulation therapy. In various examples, the medical device connected to the medical electrical leads can be a pacemaker, ICD, cardiac monitor, electroencephalogram monitor or other neuromonitor, a neurostimulator configured to deliver stimulation to brain, spinal cord or other nervous system tissue, or any other medical device that utilizes electrodes carried by the medical electrical leads to sense electrophysiological signals and / or deliver electrical stimulation therapy.

[0021] For illustrative purposes, the examples presented herein relate to cardiac medical devices, such as ICDs or pacemakers. However, it should be understood that the techniques disclosed herein can be implemented in other medical devices configured to monitor electrophysiological signals and / or deliver electrical stimulation therapy (e.g., any of the examples listed herein). A medical device operating according to the techniques disclosed herein senses and analyzes electrophysiological signals for detecting migration at the distal end of a medical electrical lead coupled to the medical device. The medical device can determine one or more features of the electrophysiological signal sensed at a baseline time point via a distal sensing electrode vector comprising at least one electrode carried along the distal portion of the medical electrical lead. The medical device can determine one or more features from the electrophysiological signal sensed at a later time point and detect migration at the distal end of the medical electrical lead based on a comparative analysis of the signal features determined at the baseline and later time points.

[0022] In the context of cardiac medical devices, a medical device can be configured to sense cardiac electrical signals and, based on the sensed cardiac electrical signals, detect migration of medical electrical leads connected to the medical device. In some examples, a medical device performing the techniques disclosed herein may include an ICD system capable of sensing cardiac electrical signals, detecting arrhythmias based on analysis of the sensed cardiac electrical signals, and delivering electrical stimulation therapy for treating the arrhythmia, for example, to promote or restore a more normal heart rhythm.

[0023] In some examples, the ICD is coupled to a cardiovascular external lead. As used herein, the term "cardiovascular external" refers to a location outside the blood vessels surrounding the patient's heart, the heart, and the pericardium. Implantable electrodes carried by a cardiovascular external lead can be positioned extrathoracically (e.g., outside the thoracic cavity and sternum) or intrathoracically (e.g., below the thoracic cavity or sternum), but are generally not in close contact with myocardial tissue; for example, not within the heart or within the pericardium. In other examples, transvenous cardiac external leads can carry implantable electrodes that can be positioned in extrathoracic locations within a vein but outside the heart, such as within an internal thoracic vein, jugular vein, or other vein, to sense cardiac electrical signals and deliver cardiac pacing pulses from locations remote from the heart.

[0024] Figure 1A and Figure 1B This is a conceptual diagram of an example of an ICD system 10 including an ICD 14 connected to a medical electrical lead 16. The ICD 14 is configured to sense cardiac electrical signals and detect migration of the lead 16 based on analysis of the sensed cardiac electrical signals. The ICD 14 can typically be configured to sense cardiac electrical signals, detect arrhythmias, and deliver electrical stimulation therapy according to the techniques disclosed herein. Figure 1A This is a front view of the ICD system 10 implanted in patient 12. Figure 1BThis is a side view of the ICD system 10 implanted in the patient 12. The ICD system 10 includes an ICD 14 connected to an electrical stimulation and sensing lead 16, which is located in an extra-cardiovascular location in this example. Figure 1A and Figure 1B Described within the context of an ICD system 10, which is capable of delivering a high-voltage CV / DF shock and / or cardiac pacing pulse in response to detection of cardiac arrhythmia based on processing of sensed cardiac electrical signals. However, the techniques disclosed herein for detecting lead migration can be implemented in cardiac monitoring devices or pacemakers that do not necessarily include CV / DF shock delivery capability in some examples. Furthermore, the techniques disclosed herein for sensing cardiac electrical signals and detecting lead migration can be implemented in a variety of medical devices, including external or implantable cardiac monitors, pacemakers, and ICDs.

[0025] The ICD 14 includes a housing 15 that forms a hermetically sealed enclosure protecting the internal components of the ICD 14. The housing 15 of the ICD 14 may be formed of a conductive material such as titanium or a titanium alloy. The housing 15 may function as an electrode (sometimes referred to as a "can" electrode). The housing 15 can be used as an active can electrode for delivering CV / DF shocks or other high-voltage pulses delivered using high-voltage therapeutic circuitry. In other examples, the housing 15 may be used to deliver unipolar, relatively low-voltage cardiac pacing pulses and / or for sensing cardiac electrical signals in conjunction with electrodes carried by leads 16. In other cases, the housing 15 of the ICD 14 may include multiple electrodes on an external portion of the housing. The external portion of the housing 15 that serves as an electrode may be coated with a material such as titanium nitride, for example, to reduce post-stimulation polarization artifacts.

[0026] The ICD 14 includes a connector assembly 17 (also referred to as a connector block or connector) that includes an electrical feedthrough through a housing 15 to provide electrical connection between a conductor extending within the lead body 18 of the lead 16 and electronic components included within the housing 15 of the ICD 14. As will be described in further detail herein, the housing 15 may house one or more processing circuits, memory, transceivers, cardiac electrical signal sensing circuitry, therapeutic delivery circuitry, power supply, and other components for sensing cardiac electrical signals, detecting heart rhythm, and controlling and delivering electrical stimulation pulses to treat abnormal heart rhythms.

[0027] The elongated lead body 18 has: a proximal end 27 including a lead connector (not shown) configured for connection to an ICD connector assembly 17; and a distal portion 25 including one or more electrodes. The elongated lead body 18 has an end and a distal end 29. Figure 1A and Figure 1BIn the example illustrated, the distal portion 25 of the lead body 18 includes defibrillation electrodes 24 and 26 and pacing / sensing electrodes 28, 30, and 31. In some cases, defibrillation electrodes 24 and 26 may form a defibrillation electrode together, as they can be configured to be activated simultaneously. Alternatively, defibrillation electrodes 24 and 26 may form a separate defibrillation electrode, in which case each of electrodes 24 and 26 can be activated independently.

[0028] Electrodes 24 and 26 (and in some examples, housing 15) are referred to herein as “defibrillation electrodes” because they can be used alone or together to deliver high-voltage stimulation therapy (e.g., CV / DF shock). Electrodes 24 and 26 may be elongated coil electrodes and generally have a relatively high surface area for delivering high-voltage electrical stimulation pulses compared to pacing and sensing electrodes 28, 30, and 31. However, in addition to or in lieu of high-voltage stimulation therapy, electrodes 24 and 26, along with housing 15, may also be used to provide pacing functionality, sensing functionality, or both pacing and sensing functionality. In this sense, the use of the term “defibrillation electrode” herein should not be construed as limiting electrodes 24 and 26 to use only in applications of high-voltage CV / DF shock therapy. For example, either electrode 24 or 26 may be used as a sensing electrode in a sensing electrode vector to sense cardiac electrical signals and determine the need for electrical stimulation therapy. Either electrode 24 or 26 can be used as a sensing electrode in a sensing electrode vector for receiving cardiac electrical signals, which are analyzed to detect migration of lead 16.

[0029] Electrodes 28, 30, and 31 are relatively small surface area electrodes that can be used in sensing electrode vectors for sensing cardiac electrical signals and, in some configurations, can be used to deliver relatively low-voltage pacing pulses. Electrodes 28, 30, and 31 are referred to as pacing / sensing electrodes because they are typically configured for use in low-voltage applications, e.g., as cathodes or anodes for delivering pacing pulses and / or sensing cardiac electrical signals, in contrast to delivering high-voltage CV / DF shocks. In some cases, electrodes 28, 30, and 31 may provide pacing functionality only, sensing functionality only, or both.

[0030] ICD 14 can acquire cardiac electrical signals corresponding to the electrical activity of the heart 8 via a combination of sensing electrode vectors including combinations of electrodes 24, 26, 28, 30, and / or 31. In some examples, the housing 15 of ICD 14 is used in combination with one or more electrodes from at least one sensing electrode vector, namely electrodes 24, 26, 28, 30, and / or 31. Various sensing electrode vectors utilizing combinations of electrodes 24, 26, 28, 30, and 31 with housing 15 for sensing one or more cardiac electrical signals are described below. Different sensing electrode vectors can be used to sense each cardiac electrical signal sensed by ICD 14, which can be selected by sensing circuitry included in ICD 14. As described herein, in some examples, the cardiac electrical signals received via the selected sensing electrode vector can be used by ICD 14 to sense electrical event signals, in this case, cardiac event signals associated with the inherent depolarization of the myocardium, such as R waves and P waves. Sensed cardiac event signals can be used to determine heart rate and the need for cardiac pacing, such as to treat bradycardia or cardiac arrest to prevent prolonged ventricular pauses, or to determine the need for treatment of tachyarrhythmias (e.g., antitachycardia pacing (ATP) or CV / DF shock). In some examples, sensed cardiac event signals can be analyzed according to the techniques disclosed herein to detect lead migration.

[0031] exist Figure 1A and Figure 1B In the example illustrated, electrode 28 is located proximal to defibrillator electrode 24, and electrode 30 is located between defibrillator electrodes 24 and 26. A third pacing / sensing electrode 31 may be located distal to defibrillator electrode 26, near or on the distal end 29 of lead body 18. Electrodes 28, 30, and 31 are illustrated as loop electrodes; however, electrodes 28, 30, and 31 may comprise any of a variety of different types of electrodes, including loop electrodes, short coil electrodes, hemispherical electrodes, directional electrodes, segmented electrodes, etc. The distal electrode 31 is shown as a loop electrode surrounding lead body 18 adjacent to the distal end 29 of lead body 18. However, electrode 31 may take the form of a tip electrode positioned on the distal end 29 of lead body 18. In this case, electrode 31 may be a screw-in helical electrode, hook electrode, button electrode, or other type of tip electrode. Electrodes 28, 30, and 31 may be positioned at other locations along lead body 18 and are not necessarily limited to the locations shown. In other examples, lead 16 may include fewer or more pacing / sensing electrodes and / or defibrillation electrodes than in the example shown here.

[0032] In the example shown, lead 16 extends from connector assembly 27 of ICD 14 toward the center of the patient 12's torso (e.g., toward the xiphoid process 20 of patient 12) and down the thoracic cavity 32 towards the central subcutaneous or submuscular region. Near the xiphoid process 20, lead 16 bends or turns upward, subcutaneously or submuscularly, above the thoracic cavity and / or sternum 22. Although in Figure 1A The lead 16 is illustrated as extending laterally offset from and substantially parallel to the sternum 22, but the distal portion 25 of the lead 16 may be implanted in other locations, such as above the sternum 22, offset to the right or left of the sternum 22, or angled laterally to the left or right of the sternum 22. Alternatively, the lead 16 may be placed along other subcutaneous or submuscular pathways. The path of the cardiovascular lead 16 may depend on the location of the ICD 14, the arrangement and positioning of the electrodes carried by the lead body 18, and / or other factors. The techniques disclosed herein for detecting the migration of the lead 16 are not necessarily limited to a specific path of the lead 16 or the final position of the electrodes 24, 26, 28, 30, and 31.

[0033] Electrical conductors (not illustrated) extend from a lead connector at the proximal lead end 27 through one or more cavities of the elongated lead body 18 of lead 16 to electrodes 24, 26, 28, 30, and 31 positioned along the distal portion 25 of lead body 18. The elongated electrical conductors contained within lead body 18 (which may be separate, corresponding insulated conductors within lead body 18) are each electrically coupled to the respective defibrillation electrodes 24 and 26 and pacing / sensing electrodes 28, 30, and 31. The respective conductors electrically couple electrodes 24, 26, 28, 30, and 31 to circuitry of ICD 14, such as treatment delivery circuitry and / or sensing circuitry, via connections in connector assembly 17 (including associated electrical feedthroughs through housing 15). The electrical conductors transmit electrical stimulation pulses from the treatment delivery circuitry within the ICD 14 to one or more of the defibrillation electrodes 24 and 26 and / or the pacing / sensing electrodes 28, 30 and 31, and transmit electrical signals generated by the patient's heart 8 from one or more of the defibrillation electrodes 24 and 26 and / or the pacing / sensing electrodes 28, 30 and 31 to the sensing circuitry within the ICD 14.

[0034] The lead body 18 of lead 16 may be formed of a non-conductive material, including silicone, polyurethane, fluoropolymers, mixtures thereof, and / or other suitable materials, and shaped to form one or more cavities in which one or more conductors extend. The lead body 18 may be tubular or cylindrical. In other examples, the distal portion 25 (or all) of the elongated lead body 18 may have a flat, strip, or paddle-like shape. The lead body 18 may be shaped to have a pre-formed distal portion 25, which is typically straight, curved, bent, serpentine, wavy, or serrated.

[0035] In the example shown, the lead body 18 includes a curved distal portion 25 with two "C"-shaped curves that together resemble the Greek letter Epsilon. The defibrillator electrodes 24 and 26 are each carried by one of the two corresponding C-shaped portions of the distal portion 25 of the lead body. The two C-shaped curves extend or bend in the same direction away from the central axis of the lead body 18, along which the pacing / sensing electrodes 28 and 30 are positioned. In some cases, the pacing / sensing electrodes 28, 30, and 31 may be substantially aligned with the central axis of the straight proximal portion of the lead body 18, such that the midpoints of the defibrillator electrodes 24 and 26 are laterally offset from the pacing / sensing electrodes 28, 30, and 31.

[0036] Other examples of cardiovascular external leads, including one or more defibrillation electrodes and one or more pacing and sensing electrodes, which can be implemented using the techniques described herein, are generally disclosed in U.S. Patent No. 10,675,478 (Marshall et al.), which is incorporated herein by reference in its entirety. 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 pre-formed shape, bends, or curves.

[0037] ICD 14 can analyze cardiac electrical signals received from sensing electrode vectors to monitor abnormal rhythms such as cardiac arrest, bradycardia, supraventricular tachycardia (SVT), ventricular tachycardia (VT), and / or ventricular fibrillation (VF). As an example, ICD 14 can analyze the heart rate and / or morphology of cardiac electrical signals to monitor long pauses, bradycardia, atrial tachyarrhythmias, and ventricular tachyarrhythmias. ICD 14 can generate and deliver electrical stimulation therapy in response to the detection of tachyarrhythmias (e.g., VT or VF (VT / VF)) using a treatment delivery electrode vector that may be selected from any of the available electrodes 24, 26, 28, 30, 31, and / or housing 15. ICD 14 can deliver ATP in response to VT detection and, in some cases, may deliver ATP before or during high-voltage capacitor charging to attempt to avoid the need for CV / DF shock delivery. If ATP fails to terminate VT or when VF is detected, ICD 14 may deliver one or more CV / DF shocks via defibrillation electrodes 24 and 26 and / or housing 15.

[0038] In the absence of a sensed ventricular event signal, such as when a prolonged pause in ventricular activity or cardiac arrest is detected, the ICD 14 can generate and deliver cardiac pacing pulses, such as post-shock pacing pulses or bradycardia pacing pulses. Cardiac pacing pulses can be delivered using a pacing electrode vector comprising one or more electrodes 24, 26, 28, 30, and 31, and the housing 15 of the ICD 14.

[0039] ICD 14 is shown subcutaneously implanted on the left side of patient 12 along thoracic cavity 32. In some cases, ICD 14 may be implanted between the left posterior axillary line and the left anterior axillary line of patient 12. However, ICD 14 may be implanted in other subcutaneous or submuscular locations in patient 12. For example, ICD 14 may be implanted in a subcutaneous pouch in the pectoral muscle region. In this case, lead 16 may extend subcutaneously or submuscularly from ICD 14 toward the manubrium of sternum 22, and bend or turn downward from the manubrium and extend to the desired subcutaneous or submuscular location. In yet another example, ICD 14 may be placed in the abdomen. Lead 16 may also be implanted in other extravascular locations. For example, as per [reference to...] Figures 2A to 2C As described, the distal portion 25 of the lead 16 can be implanted under the sternum / pleural cavity in the substernal space. Figure 1A and Figure 1B This is illustrative in nature and should not be considered as limiting the practice of the techniques disclosed herein.

[0040] Medical devices operating according to the techniques disclosed herein can be coupled to transvenous or non-transvenous leads, in various examples, for carrying electrodes used to sense cardiac electrical signals and deliver electrical stimulation therapy. For example, a medical device such as the ICD 14 can be coupled to a cardiovascular external lead, as illustrated in the accompanying figures, which refers to a lead that positions the electrodes outside a patient's blood vessels, heart, and the pericardium surrounding the heart. Implantable electrodes carried by a cardiovascular external lead can be positioned extrathoracically (outside the thoracic cavity and sternum), subcutaneously, or submuscularly, or intrathoracically (below the thoracic cavity or sternum, sometimes referred to as substernal positioning), and may not necessarily be in close contact with myocardial tissue. Cardiovascular external leads can also be referred to as "non-transvenous" leads.

[0041] In other examples, the medical device may be coupled to a transvenous lead that positions electrodes within a blood vessel, which may be held in an “extracardiac” position outside the heart or advanced to position the electrodes within a cardiac chamber. For example, as an example, the transvenous medical lead may be advanced along a venous pathway to position the electrodes in an extracardiac position within an internal thoracic vein (ITV), intercostal vein, epigastric vein, or azygos vein, hemiazygos vein, or accessory hemiazygos vein.

[0042] exist Figure 1AIn the diagram, external device 40 is shown communicating telemetry with ICD 14 via wireless communication link 42. External device 40 may include processor 52, memory 53, display 54, user interface 56, and telemetry unit 58. Processor 52 controls the operation of the external device and processes data and signals received from ICD 14. Display unit 54, which may include a graphical user interface, displays data and other information to the user to view parameters for ICD operation and programming, as well as cardiac electrical signals retrieved from ICD 14.

[0043] User interface 56 may include a mouse, touchscreen, keypad, etc., to enable users to interact with external device 40 to initiate telemetry sessions with ICD 14 in order to retrieve data from and / or send data to ICD 14, including programmable parameters for controlling cardiac event signal sensing, arrhythmia detection, and treatment delivery. 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 functionality via communication link 42.

[0044] You can use something like BLUETOOTH ® A communication link 42 is established between the ICD 14 and the external device 40 via a radio frequency (RF) link, such as Wi-Fi, Medical Implantable Communication Service (MICS), or other RF or communication frequency bandwidth or communication protocol. Data stored or acquired by the ICD 14, including physiological signals or associated data derived therefrom, device diagnostic results, battery status, and the history of detected rhythm episodes and delivered treatments, can be retrieved by the external device 40 from the ICD 14 upon request. The ICD 14 may send a notification or alarm to the external device 40 after detecting migration of the lead 16.

[0045] External device 40 may be embodied as a programmer used in a hospital, clinic, or physician's office to retrieve data from ICD 14 and program the operating parameters and algorithms in ICD 14 to control ICD functions. External device 40 may alternatively be embodied as a home monitor or a handheld device. External device 40 can be used to program cardiac signal sensing parameters, cardiac rhythm detection parameters, and treatment control parameters used by ICD 14. In some examples, external device 40 may be used to program at least some control parameters used for sensing cardiac event signals, detecting arrhythmias, detecting lead migration, and controlling treatment delivery into ICD 14.

[0046] Figures 2A to 2C Is it implanted in a position with Figures 1A to 1B A conceptual diagram of a patient 12 with different implantation configurations of an extravascular ICD system 10. Figure 2AThis is a front view of a patient 12 with an implanted ICD system 10. Figure 2B This is a side view of patient 12 who has an ICD system 10 implanted. Figure 2C This is a transverse view of a patient 12 with an ICD system 10 implanted. In this arrangement, the external cardiovascular lead 16 of the system 10 is at least partially implanted below the sternum 22 of the patient 12. The lead 16 extends subcutaneously or submuscularly from the ICD 14 toward the xiphoid process 20, and bends or turns within the anterior mediastinum 36 and extends upwards at a substernal location near the xiphoid process 20 (see [link to ICD 10]). Figure 2C ).

[0047] The anterior mediastinum 36 can be considered to be laterally defined by the pleura 39, posteriorly defined by the pericardium 38, and anteriorly defined by the sternum 22 (see [reference]). Figure 2C The distal portion 25 of the guide 16 may extend substantially within the loose connective tissue and / or substernal muscle tissue of the anterior mediastinum 36 along the posterior side of the sternum 22. A guide implanted such that the distal portion 25 is substantially within the anterior mediastinum 36 may be referred to as a “substernal guide”.

[0048] exist Figures 2A to 2C In the illustrated example, lead 16 is positioned substantially below the sternum 22. However, in other cases, lead 16 may be implanted such that it is laterally offset from the center of the sternum 22. In some cases, lead 16 may extend laterally such that, in addition to or in place of the sternum 22, the distal portion 25 of lead 16 is below / below the pleural cavity 32. In other examples, the distal portion 25 of lead 16 may be implanted in other intrathoracic locations outside the heart, including within the pleural cavity or around and adjacent to or within the pericardium 38 of the heart 8.

[0049] The distal portions 25 of the carrier electrodes 24, 26, 28, 30, and 31 can be advanced to the implantation site by tunneling the distal end 29 of the lead 16, for example, along subcutaneous, submuscular, and / or substernal pathways through tissue layers and / or between tissue layers. The distal end 29 of the lead 16 may remain as a free end, which is not secured in its final position by sutures or any other fixation member or mechanism. When implanted transvenously, the distal end 29 may migrate, for example, advance or retract, but generally remains defined within the vascular lumen. When implanted in a non-transvenous location, the distal end 29 may migrate laterally, for example, in a direction relative to the right or left, may advance (e.g., generally upward or cranial) or retract (e.g., generally downward or caudal), and in some cases may shift further forward or backward. In some examples, the lead 16 may be provided with a fixation member, such as a spiral screw, hook, one or more serrations, or other fixation member at its distal end 29, to stabilize the distal end 29 in the implantation site. However, regardless of whether it is anchored by a fixation member (e.g., a suture or a fixation member provided as part of lead 16), the distal end 29 may migrate over time, causing the cardiac electrical signal sensed using the electrode carried by its distal portion 25 to change over time. Because the maximum migration may occur at the free distal end 29 (relative to the proximal end 27 attached to the ICD 14), the cardiac electrical signal sensed using the distal end 29 or the most distal electrode 31 closest to that distal end may change over time to a greater extent than the electrical signal sensed using a more proximal sensing electrode vector (e.g., a sensing electrode vector excluding the distal electrode 31).

[0050] Changes in cardiac electrical signals sensed using lead 16 over time may alter the reliability of sensing cardiac event signals (e.g., sensing of R waves with ventricular depolarization and / or P waves with atrial depolarization). Insufficient or excessive sensing of cardiac event signals may lead to undersensitivity or oversensitivity of arrhythmias by the ICD 14, potentially resulting in the delivery of electrical stimulation therapy when unnecessary or not when necessary. Thus, the techniques disclosed herein can be used to detect migration of medical electrical leads that can be implanted in extracardiac locations, enabling notification to patients and / or caregivers of lead migration and / or changes made by the ICD 14 in one or more control parameters used in cardiac electrical signal sensing, detection of cardiac event signals (e.g., P and R waves), arrhythmia detection, and / or treatment delivery.

[0051] Figure 3 This is based on a conceptual diagram of an example ICD 14. The electronic circuitry is enclosed within a housing 15 (in... Figure 3The ICD (conceptually shown as an electrode) may include software, firmware, and / or hardware that collaboratively monitor cardiac electrical signals, determine when electrical stimulation therapy is needed, and deliver therapy as needed based on a programmed therapy delivery algorithm and control parameters. The ICD 14 may be coupled to leads, such as lead 16 carrying electrodes 24, 26, 28, 30, and 31, for delivering electrical stimulation pulses to the patient's heart and for sensing cardiac electrical signals.

[0052] The ICD 14 includes control circuitry 80, memory 82, treatment delivery circuitry 84, cardiac electrical signal sensing circuitry 86, and telemetry circuitry 88. A power supply 98 supplies power to the circuitry of the ICD 14 as needed, including each of components 80, 82, 84, 86, and 88. The power supply 98 may include one or more energy storage devices, such as one or more rechargeable or non-rechargeable batteries. Connections between the power supply 98 and each of the other components 80, 82, 84, 86, and 88 will be made from... Figure 3 The overall block diagram is for understanding purposes, but is not shown for clarity. For example, power supply 98 may be coupled to one or more charging circuits included in the treatment delivery circuit 84 for charging holding capacitors included in the treatment delivery circuit 84, which discharge at appropriate times under the control of control circuit 80 to generate electrical pulses according to the treatment protocol. Power supply 98 may also be coupled to components of the cardiac electrical signal sensing circuit 86 as needed, such as sensing amplifiers, analog-to-digital converters, switching circuits, etc.

[0053] Figure 3 The circuitry illustrated represents the functionality included in ICD 14 and may include any discrete and / or integrated electronic circuitry components implementing analog and / or digital circuitry capable of producing the functions attributed herein to ICD 14. The functionality associated with one or more circuits may be performed by separate hardware components, firmware components, and / or software components, or integrated within common hardware components, firmware components, and / or software components. For example, the sensing and analysis of cardiac electrical signals for detecting arrhythmias or lead migration, as disclosed herein, may be performed cooperatively by sensing circuitry 86 and control circuitry 80, and may include the execution of instructions stored in memory 82 implemented in a processor or other signal processing circuitry included in sensing circuitry 86 and / or control circuitry 80. Control signals such as blanking and timing periods, as well as sensing threshold amplitude, may be stored in memory 82 and retrieved by control circuitry 80 for use by sensing circuitry 86. The sensing threshold amplitude may be applied to the sensed electrophysiological signals for sensing electrical event signals.

[0054] Control circuitry 80 and sensing circuitry 86 may include hardware configured to execute subroutines of the signal processing and analysis techniques disclosed herein to reduce the processing burden associated with firmware and / or software execution of the processing routines. For example, hardware subroutines (HSRs) may be implemented in sensing circuitry 86 and control circuitry 80 to perform specific processing functions such as dedicated mathematical operations, including sums, absolute values, differences, ratios, products, extrema, histogram counting, signal filtering (e.g., biquadratic filters, difference filters, or other filters), etc. These HSRs may be invoked by the control circuitry firmware when processing and analyzing cardiac signals used to sense cardiac event signals, detect lead migration, and / or detect arrhythmias. These HSRs offload the processing burden associated with firmware and / or software processing to reduce current consumption of power supply 98 and thereby extend the lifespan of ICD 14. For example, as further described below, mathematical operations performed on sample points (operands) of two different cardiac electrical signals sensed by ICD 14 to determine one or more cardiac sensing signals from which a cardiac event signal was detected can be performed by an HSR included in sensing circuit 86 or control circuit 80.

[0055] Various circuits of the ICD 14 may include application-specific integrated circuits (ASICs), electronic circuits, (shared, dedicated, or group) processors and memories executing one or more software or firmware programs, combinational logic circuits, state machines, HSRs, or other suitable components or combinations of components that provide the described functionality. The specific form of the software, hardware, and / or firmware used to implement the functionality disclosed herein will be determined primarily by the specific system architecture employed in the ICD and the specific sensing, detection, and therapeutic delivery methods employed by the ICD. Given the disclosure herein, providing software, hardware, and / or firmware to implement the described functionality in the context of any modern medical device system is within the capabilities of those skilled in the art.

[0056] Memory 82 may include any volatile, non-volatile, magnetic, or electrically non-transitory computer-readable storage medium, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other memory device. Furthermore, memory 82 may include a non-transitory computer-readable medium storing instructions that, when executed by one or more processing circuits, cause control circuitry 80, sensing circuitry 86, and / or other ICD components to perform various functions belonging to ICD 14 or those ICD components. The non-transitory computer-readable medium storing instructions may include any of the media listed above.

[0057] Control circuitry 80 communicates, for example, via a data bus with treatment delivery circuitry 84 and sensing circuitry 86 to sense cardiac electrical signals, detect cardiac rhythm, and control the delivery of cardiac electrical stimulation therapy in response to the sensed cardiac signals. Treatment delivery circuitry 84 and sensing circuitry 86 may be electrically coupled to electrodes 24, 26, 28, 30, and 31 carried by leads 16 and / or housing 15, which may serve as a common or ground electrode or as an active can electrode for delivering CV / DF shock pulses or cardiac pacing pulses.

[0058] Cardiac electrical signal sensing circuit 86 (also referred to herein as “sensing circuit” 86) may be selectively coupled to electrodes 28, 30, and 31 and / or housing 15 to monitor the electrical activity of a patient’s heart. Sensing circuit 86 may additionally and selectively couple to defibrillation electrodes 24 and / or 26 for use in a sensing electrode vector together or in combination with one or more of electrodes 28, 30, and 31 and / or housing 15. In some examples, sensing circuit 86 may be made capable of receiving cardiac electrical signals from at least one sensing electrode vector selected from available electrodes 24, 26, 28, 30, and 31 and housing 15. In some examples, at least two, three, or more cardiac electrical signals from two, three, or more different sensing electrode vectors may be received simultaneously by sensing circuit 86. Sensing circuit 86 may monitor cardiac electrical signals in one or more instances for sensing cardiac event signals, such as P waves associated with intrinsic atrial myocardial depolarization and R waves associated with intrinsic ventricular myocardial depolarization.

[0059] In some examples, sensing circuitry 86 may include multiple sensing channels 81, 83, 85, and 87 for simultaneously receiving multiple cardiac electrical signals to sense cardiac event signals and perform cardiac electrical signal morphology analysis. Sensing circuitry 86 may include switching circuitry 89 for selecting which electrodes 24, 26, 28, 30, 31 and housing 15 are coupled to each sensing channel 81, 83, 85, and 87. In this example, sensing circuitry 86 includes an atrial (A) sensing channel 81, a first ventricular (V) sensing channel 83, a second ventricular (V) sensing channel 85, and a morphological signal channel 87. In some cases, switching circuitry 89 may be controlled by control circuitry 80 to select different sensing electrode vectors for electrical coupling to a given sensing channel 81, 83, 85, or 87 for sensing cardiac signals used to detect lead migration, rather than when sensing circuitry 86 is operating to perform cardiac event signal sensing for the purpose of monitoring heart rhythm. Thus, one or more sensing electrode vectors used to sense cardiac electrical signals for monitoring heart rhythm can be different from one or more sensing electrode vectors used to detect lead migration.

[0060] Each sensing channel 81, 83, 85, and 87 can be configured to amplify, filter, and digitize the cardiac electrical signals received from the corresponding sensing electrode vector to improve the quality of the received signals used for sensing cardiac event signals and for signal morphology analysis. The cardiac event detection circuitry within sensing circuitry 86 may include one or more sensing amplifiers, filters, rectifiers, threshold detectors, comparators, analog-to-digital converters (ADCs), timers, or other analog and / or digital components, such as in combination. Figure 4 Further described. The cardiac event sensing threshold can be automatically adjusted by each sensing channel 81, 83, and 85 under the control of the control circuit 80, based on sensing threshold control parameters (such as various time periods) and sensing threshold amplitude values ​​that can be determined by the control circuit 80, stored in the memory 82, and / or controlled by the hardware, firmware, and / or software of the control circuit 80 and / or the sensing circuit 86. For example, sensing channel A 81 can apply a P-wave sensing threshold to the incoming cardiac electrical signal for sensing atrial P waves. Each of sensing channels V 83 and 85 can apply an R-wave sensing threshold to the corresponding incoming cardiac electrical signal for sensing ventricular R waves. P waves and R waves are examples of electrical event signals that can be sensed from electrophysiological signals (in this case, cardiac electrical signals) based on the electrical event sensing threshold exceeding the limit.

[0061] When a cardiac event signal is sensed based on a sensing threshold exceeding a certain limit, sensing circuit 86 can transmit the cardiac sensing event signal (e.g., an atrial sensing event (Asense) signal or a ventricular sensing event (Vsense) signal) to control circuit 80. The Asense and Vsense signals received by control circuit 80 from sensing circuit 86 can be used by control circuit 80 to determine the sensing event interval, such as the PP interval (PPI) and RR interval (RRI), and in some cases, the PR interval (PRI) and / or RP interval (RPI). PPI is the time interval between two consecutively received Asense event signals received by control circuit 80 from sensing channel A 81. RRI is the time interval between two consecutive Vsense signals received by control circuit 80 from the same V sensing channel 83 or 85; this can also be referred to as the "intra-channel" sensing event interval. PRI is the time interval from an atrial event (sensed or paced) to the next Vsense signal. RPI is the time interval from a ventricular event (sensed or paced) to the next Asense signal. In some cases, the RRI from the pacing pulse to the Vsense signal is determined when a Vsense signal is received after the delivered pacing pulse. Thus, the cardiac event interval can include the time interval from the pacing pulse delivered by the treatment delivery circuit 84 to the cardiac sensing event signal received from the sensing circuit 86. The control circuit 80 may include timing circuitry 90 for determining cardiac event intervals such as PPI and RRI. Based on the determined PPI and / or RRI (and in some examples RPI and / or PRI), the control circuitry 80 can detect atrial and / or ventricular arrhythmias, such as bradycardia, cardiac arrest, SVT, VT, and / or VF.

[0062] The exemplary techniques disclosed herein are described in conjunction with a sensing circuit 86 including at least one A sensing channel 81 and at least one V sensing channel 83. (The following is a continuation of the previous paragraph.) Figure 4 As described, the A-sensing channel 81 can receive cardiac electrical signals, also referred to as "atrial signals," from the atrial sensing electrode vector. The A-sensing channel 81 can additionally receive ventricular signals from the V-sensing channels 83 or 85 for determining the atrial sensing signal. The "atrial sensing signal" can be determined as a combination of the received atrial and ventricular signals. The atrial sensing signal can be a signal determined from at least two received signals, which are combined, for example, according to one or more mathematical operations to generate an atrial sensing signal from which an atrial event signal is detected. The A-sensing channel 81 can apply a P-wave sensing threshold to the atrial sensing signal for sensing the P wave (as an atrial event signal). In some examples, two (or more) A-sensing channels can be included to enable the control circuitry 80 to verify Asense event signals received from two different A-sensing channels.

[0063] Combined with the following text Figure 4 As described, V sensing channel 83 or 85 can receive cardiac electrical signals, also referred to as "ventricular signals," from the ventricular sensing electrode vector. In some examples, V sensing channel 83 or 85 may additionally receive atrial signals from A sensing channel 81 to determine the ventricular sensing signal. The "ventricular sensing signal" can be determined as a combination of the received atrial and ventricular signals. The ventricular sensing signal can be a signal determined from at least two received signals, which are combined, for example, according to one or more mathematical operations to generate a ventricular sensing signal from which a ventricular event signal is detected. V sensing channel 83 or 85 may apply an R-wave sensing threshold to the ventricular sensing signal to sense the R-wave (sensed as a ventricular event signal).

[0064] In some examples, a second V-sensing channel 85 may be included in sensing circuitry 86. Control circuitry 80 may be configured to verify a V-sense signal received from one V-sensing channel based on a V-sense signal received from the second V-sensing channel. For example, when a V-sense signal is received from the second V-sensing channel 85 or 83 within a verification time window from the first V-sensing channel, the V-sense signal received from the first V-sensing channel 83 or 85 may be identified as a genuine or valid V-sense signal. Examples of techniques for dual-channel sensing of ventricular event signals, which may be performed by control circuitry 80 for verifying V-sense signals received from both V-sensing channels, are generally disclosed in U.S. Patent Application Publication No. 2023 / 0100431A1 (filed August 29, 2022 by Liu et al.), the entire contents of which are incorporated herein by reference.

[0065] like Figure 3As shown, sensing circuit 86 may include a morphological signal channel 87 for transmitting a digital electrocardiogram (ECG) signal to control circuit 80 to perform morphological analysis. Control circuit 80 may be configured to enable or disable morphological signal channel 87 to sense cardiac electrical signals, which may be transmitted to control circuit 80 for processing and analysis. Time segments of the morphological signal received from morphological signal channel 87 may be buffered in memory 82. In various examples, relatively short time segments may be buffered in response to a Vsense signal received from at least one of V-sensing channels 83 or 85, for example, durations of 150 ms to 600 ms or approximately 180 ms to 500 ms. Morphological analysis (e.g., R-wave morphology matching) may be performed to verify the Vsense signal as a true R-wave, or in some cases, to identify possible VT / VF waveforms (e.g., non-sinus QRS waveforms based on low R-wave morphology matching scores). In other examples, control circuitry 80 may be configured to enable morphological signal channel 87 to sense and transmit morphological signals for buffering, processing, and analyzing relatively long cardiac signal segments, such as, for example, segments of 0.5 to 5 seconds or 0.5 to 3 seconds. The relatively long cardiac signal segments can be obtained independently of the relative timing of Vsense or Asense event signals received from sensing circuitry 85. For example, when no Asense or Vsense signal is received, relatively long cardiac signal segments can be analyzed to detect cardiac arrest. Relatively long cardiac signal segments can be analyzed to detect evidence of VT / VF, for example, when V sensing channels 83 and 85 may be insufficiently sensing fibrillation waves or low-amplitude R waves.

[0066] Four cardiac electrical signals received by sensing channels 81, 83, 85 and morphological signal channel 87 can be received from four different sensing electrode vectors selected from available electrodes 24, 26, 28, 30, and 31 and housing 15. In other examples, sensing circuit 86 can receive two cardiac electrical signals from two different sensing electrode vectors, one signal being passed to the first V sensing channel 83 and the other signal being passed to the A sensing channel 81. Either or both of these signals can be passed as a multi-digit ECG signal to control circuit 80, which is used by control circuit 80 for morphological analysis of predetermined time segments of the ECG signal to detect arrhythmias. A third cardiac electrical signal can be received by the second V sensing channel 85 (if included). The following is in conjunction with... Figure 4 An example of a sensing electrode vector that can be switchably connected to multiple sensing channels of sensing circuit 86 is described.

[0067] The control circuit 80 may include a timing circuit 90 and an arrhythmia detection circuit 92. The timing circuit 90 may be configured to control various timers and / or counters for setting various time intervals and windows for sensing cardiac event signals, determining the time interval between received Asense event signals and Vsense signals, performing morphological analysis, and controlling the timing of cardiac pacing pulses and CV / DF shocks generated by the treatment delivery circuit 84. The timing circuit 90 may activate various timers in response to receiving Asense event signals and Vsense signals from the sensing circuit 86 for timing cardiac event intervals (e.g., PPI and RRI) between continuously received cardiac event signals. The timing circuit 90 may pass the cardiac event intervals to the arrhythmia detection circuit 92 for detecting and counting tachyarrhythmia intervals.

[0068] The arrhythmia detection circuit 92 can be configured to analyze cardiac event intervals received from the timing circuit 90, and in some examples, analyze cardiac electrical signals (also referred to herein as "morphological signals") received from the morphological signal channel 87 for arrhythmia detection. The arrhythmia detection circuit 92 can be configured to detect long ventricular pauses, cardiac arrest, SVT, and / or VT / VF based on the sensed cardiac electrical signals meeting corresponding detection criteria. For example, the control circuit 80 can detect VT / VF when a threshold number of Vsense signals from a sensing channel 83 or 85 each occur with a sensing event interval (RRI) smaller than the tachyarrhythmia detection interval. RRIs smaller than the tachyarrhythmia detection interval can be counted as tachyarrhythmia intervals. In some examples, tachyarrhythmia detection based on a threshold number of tachyarrhythmia intervals can be confirmed or rejected based on morphological analysis of the morphological signals received from the morphological channel 87. The arrhythmia detection circuit 92 can be implemented in the control circuit 80 as hardware, software, and / or firmware for processing and analyzing signals received from the sensing circuit 86 to detect arrhythmias according to various arrhythmia detection algorithms. In some examples, the arrhythmia detection circuit 92 may include a comparator and a counter for counting PPI and RRI falling into various rate detection zones as determined by the timing circuit 90 to determine atrial and ventricular rates or to perform other rate-based or interval-based evaluations of the Asense event signal and Vsense signal, thereby detecting and distinguishing between SVT and VT / VF.

[0069] For example, the arrhythmia detection circuit 92 can compare the RRI determined by the timing circuit 90 with one or more rapid arrhythmia detection interval zones (such as tachycardia detection interval zones and fibrillation detection interval zones). RRIs falling within the detection interval zone are counted by the corresponding VT interval (VTI) counter or VF interval (VFI) counter, and in some cases, by a combined VT / VF interval counter. For example, the VF detection interval threshold can be set from 300 milliseconds (ms) to 350 ms. For example, if the VF detection interval is set to 320 ms, the VFI counter counts RRIs less than 320 ms. When VT detection is enabled, the VT detection interval can be programmed to be in the range of 350 ms to 420 ms, or programmed to, for example, 400 ms. RRIs less than the VT detection interval but greater than or equal to the VF detection interval can be counted by the VTI counter. VT or VF can be detected when the corresponding VT or VFI counter (or the combined VT / VF interval counter) reaches the threshold number of detection intervals (NID).

[0070] For example, the NID required to detect VT may require the VTI counter to reach 18, 24, 32, or other selected NIDs. In some examples, the VTIs may need to be consecutive intervals, such as 18 out of 18, 24 out of 24, or 32 out of 32, or 100 out of the most recent 100 consecutive RRIs. The NID required to detect VF can be programmed as a threshold number of X VFIs out of Y consecutive RRIs. For example, as an example, the NID required to detect VF could be 18 VFIs out of the most recent 24 consecutive RRIs, 30 VFIs out of 40 consecutive RRIs, or up to 120 VFIs out of 160 consecutive RRIs (or another percentage of a specified number of RRIs). When the VTI or VFI counter reaches the corresponding NID, the arrhythmia detection circuit 92 can detect the ventricular tachyarrhythmia. The NID can be programmable and is not limited to a range from as low as 12 to as high as 120. When VTI or VFI is detected sequentially or discontinuously from a specified number of recent RRIs, the VTI counter or VFI counter reaches the corresponding NID. In some cases, a combined VT / VF interval counter can count both VTI and VFI and detect tachyarrhythmia episodes based on the fastest interval detected when a specified NID is reached.

[0071] The arrhythmia detection circuit 92 can also be configured to detect atrial tachyarrhythmia (AT) intervals based on PPIs received from the timing circuit 90, and to count the AT intervals for SVT detection. In some examples, the arrhythmia detection circuit 92 can detect SVT, such as atrial fibrillation, based on analysis of RRI variability. Detection of SVT by the arrhythmia detection circuit 92 enables the control circuit 80 to distinguish between SVT and VT / VF to appropriately control CV / DF shock delivery, thereby treating potentially life-threatening tachyarrhythmias.

[0072] The arrhythmia detection circuit 92 can be configured to perform additional signal analysis to determine whether other detection criteria, such as P-wave morphology criteria and / or R-wave morphology criteria, episodic criteria, stability criteria, noise, and oversensing rejection criteria, are met before SVT or VT / VF can be detected, based on the achievement of NID. To support these additional analyses, the sensing circuit 86 can transmit digitized morphological signals from the morphological signal channel 87 to the control circuit 80 for morphological analysis performed by the arrhythmia detection circuit 92, thereby detecting and differentiating heart rhythms. The cardiac electrical signals received by the morphological signal channel 87 (and / or any of the sensing channels 83, 85, or 87) can be passed through filters and amplifiers, provided to a multiplexer, and subsequently converted into multi-bit digital signals by an analog-to-digital converter, all of which are included in the sensing circuit 86 for storage in the memory 82. The memory 82 may include one or more loop buffers to temporarily store segments of digital cardiac signals used for analysis performed by the control circuit 80. The control circuit 80 may be a microprocessor-based controller (which may include an HSR) that employs digital signal analysis techniques to characterize the digitized signals stored in memory 82 in order to identify and classify the patient’s heart rhythm using any of a variety of signal processing methods for analyzing cardiac signals and cardiac event waveforms (e.g., P waves and sinus or non-sinus R waves).

[0073] The treatment delivery circuit 84 includes at least one charging circuit 94, which includes one or more charge storage devices, such as one or more high-voltage capacitors for generating high-voltage shock pulses for treating VT / VF. The charging circuit 94 may include one or more low-voltage capacitors for generating relatively low-voltage pulses (e.g., for cardiac pacing therapy). The treatment delivery circuit 84 may include a switching circuit 95 that controls when the charge storage devices discharge across a selected pacing electrode vector or CV / DF shock vector via an output circuit 96.

[0074] In response to the detection of VT / VF, control circuit 80 can schedule treatment and control treatment delivery circuit 84 to generate and deliver treatments, such as ATP and / or CV / DF shocks. Treatment can be generated by initiating charging of a high-voltage capacitor in charging circuit 94. Charging is controlled by control circuit 80, which monitors the voltage on the high-voltage capacitor, which is transmitted to control circuit 80 via a charging control line. When the voltage reaches a predetermined value set by control circuit 80, a logic signal is generated across the entire capacitor line and transmitted to treatment delivery circuit 84, thereby terminating charging. CV / DF shock pulses are delivered to the heart via a control bus through output circuit 96 of treatment delivery circuit 84 under the control of timing circuit 90. Output circuit 96 may include an output capacitor or other output circuit through which the charged high-voltage capacitor discharges via a switching circuit (e.g., an H-bridge) that determines the electrode for delivering cardioversion or defibrillation pulses and pulse shape. Treatment delivery circuit 84 may be configured to receive a signal from external device 40 during ICD implantation or subsequent testing procedures. Figure 1A When programmed, electrical stimulation pulses are delivered to induce rapid arrhythmias (e.g., T-wave impulses or induced pulse trains).

[0075] In some examples, a high-voltage treatment circuit configured to deliver CV / DF shock pulses can be controlled by control circuitry 80 to deliver pacing pulses, such as those for delivering ATP, post-shock pacing pulses, bradycardia pacing pulses, atrial-synchronized ventricular pacing pulses, or cardiac arrest pacing pulses for pacing and capturing the ventricles. Treatment delivery circuitry 84 can be configured to generate and deliver cardiac pacing pulses using a high-voltage capacitor that can be charged to the shock voltage amplitude by charging the high-voltage capacitor to a relatively low voltage corresponding to the cardiac pacing pulse amplitude used to capture and pace the ventricular myocardium. Treatment delivery circuitry 84 may include low-voltage treatment circuitry comprising one or more separate or shared charging circuits, switching circuits, and output circuits for generating and delivering relatively low-voltage pacing pulses for capturing and pacing the ventricles for various pacing needs. The charging of the capacitor to a programmed pulse amplitude and the discharging of the capacitor for a programmed pulse width can be performed by treatment delivery circuitry 84 according to a control signal received from control circuitry 80 for delivering cardiac pacing pulses for capturing the ventricles. The timing circuit 90 may include various timers or counters to control when cardiac pacing pulses are delivered, for example, by timeouts of various pacing escape intervals. The microprocessor of the control circuit 80 may set the amplitude, pulse width, polarity, or other characteristics of the cardiac pacing pulses based on programmable values ​​stored in memory 82. The circuitry included in the treatment delivery circuitry 84 for generating and delivering electrical stimulation pulses according to a treatment delivery protocol may vary between medical devices and is not limited to any particular treatment delivery circuitry configuration used in conjunction with the cardiac signal sensing and lead migration detection methods disclosed herein.

[0076] Control parameters used by control circuit 80 to sense cardiac event signals, detect arrhythmias, and control treatment delivery can be programmed into memory 82 via telemetry circuit 88. Telemetry circuit 88 includes a transceiver and an antenna for communicating with external device 40 using RF communication or other communication protocols as described above. Figure 1A (As shown) to communicate. Under the control of the control circuit 80, the telemetry circuit 88 can receive downlink telemetry from the external device 40 and send uplink telemetry to the external device.

[0077] Figure 4 It is based on some examples Figure 3 The diagram shows a conceptual illustration of the circuitry that may be included in the sensing circuitry 86. The sensing circuitry 86 may include an A sensing channel 81, at least one V sensing channel 83, optionally a second V sensing channel 85, and in some examples, a morphological signal channel 87.

[0078] Sensing channel 81 can receive cardiac electrical signals, referred to as "atrial signals," via an atrial sensing electrode vector. Sensing channel 81 can be selectively coupled to the atrial sensing electrode vector via a switching circuit included in sensing circuit 86, the atrial sensing electrode vector comprising leads 16 (e.g., in...). Figure 1A (As shown in the image) at least one electrode carried. Figures 1A to 2C In the implantation location shown, the distal electrode 31 is located at or near the distal end 29 of the lead 16 (e.g., see...). Figure 1A The sensor can be operatively located close to the atrial ventricle for sensing P waves. For example, cardiac electrical signals received via electrodes 31 and 30 may include P waves with signal strength that facilitates reliable P wave sensing by the A-sensing channel 81. In the illustrated example, the A-sensing channel 81 receives cardiac electrical signals from electrodes 31 and 30. In other examples, the A-sensing channel 81 may receive cardiac electrical signals from electrode 31 paired with one of defibrillation electrodes 24 or 26 or housing 15. Depending on the position and orientation of the lead 16 relative to the patient's heart, electrode 30 or electrode 28 may be operatively located close to the atrial ventricle and may be used in an atrial sensing electrode vector. In some examples, the atrial sensing electrode vector selected for receiving atrial signals by the A-sensing channel 81 includes at least one electrode carried by the lead 16 that is physically closest to the atrium of the patient's heart. In some examples, the atrial sensing electrode vector selected for receiving atrial signals by the A-sensing channel 81 includes two pacing / sensing electrodes carried by the lead 16 that are physically closest to the atrium of the patient's heart. In some examples, the atrial signal received by sensing channel A 81 via an atrial sensing electrode vector including at least the distal electrode 31 can be analyzed by control circuitry 80 for detecting distal vector signals of lead migration.

[0079] V-sensing channels 83 and 85 can each receive cardiac electrical signals used in sensing ventricular event signals. The first V-sensing channel 83 and the second V-sensing channel 85 can each be selectively coupled via a switching circuit 89 included in sensing circuit 86 to a corresponding ventricular sensing electrode vector including at least one electrode carried by lead 16. The first V-sensing channel 83 can be coupled to a first ventricular sensing electrode vector for receiving a first ventricular signal, and the second V-sensing channel 85 can be coupled to a second ventricular sensing electrode vector different from the first ventricular sensing electrode vector for receiving a second ventricular signal different from the first ventricular signal. In some examples, the first V-sensing channel 83 can be coupled to a ventricular sensing electrode vector that is a short bipolar vector with a relatively shorter interelectrode distance than the ventricular sensing electrode vector coupled to the second V-sensing channel 85 or the morphological signal channel 87. In the example shown, the first V-sensing channel 83 is coupled to pacing / sensing electrodes 28 and 30 carried by lead 16. In some examples, the first V-sensing channel 83 may be coupled to a sensing electrode vector that is approximately vertical (when the patient is in an upright position) or approximately aligned with the cardiac axis to increase the likelihood of a relatively high R-wave signal amplitude relative to the P-wave signal amplitude. As used herein, the term "cardiac axis" refers to the electrical axis of the heart, which represents the overall mean direction of ventricular depolarization (QRS complex). In normal patients, the cardiac axis can be between -30 degrees and +60 degrees, but can deviate from this range, where the measured angle is positive in the clockwise direction, starting from the transverse plane or axis, where zero degrees points to the patient's left side. A relatively short interelectrode distance (e.g., between electrodes 28 and 30 carried by lead 16) may be relatively less likely to be contaminated by skeletal muscle electromyographic noise, EMI, or other non-cardiac noise compared to a relatively long interelectrode distance, but may have greater variability in R-wave signal intensity compared to a relatively long interelectrode distance.

[0080] In some examples, the second V-sensing channel 85 may be optional and may be coupled to a second ventricular sensing electrode vector that is a short bipolar or relatively long bipolar compared to the first ventricular sensing electrode vector. The second ventricular sensing electrode vector may also be substantially perpendicular to or aligned with the cardiac axis. However, in other examples, the second ventricular sensing electrode vector may be orthogonal or transverse relative to the first ventricular sensing electrode vector. In the example shown, the second V-sensing channel 85 is coupled to the pacing / sensing electrode 30 and the housing 15 such that it is a relatively long bipolar that is substantially transverse to the ventricular sensing electrode vector coupled to the first V-sensing channel 83. In other examples, the first or second V-sensing channel may be coupled to either the pacing / sensing electrode 28 or 30 paired with the housing 15, either the pacing / sensing electrode 28 or 30 paired with the coil electrode 24, or either the pacing sensing electrode 28 or 30 paired with the coil electrode 26, provided that at least one electrode between the two V-sensing electrode vectors is different. In another example, either or both of the first V sensing channel 83 or the second V sensing channel 85 may be coupled to a sensing electrode vector that does not necessarily include one of the pacing / sensing electrodes 28, 30, or 31. For example, the sensing electrode vector may be coupled to sensing channel 83 or sensing channel 85 that includes one or both of the coil electrodes 24 or 26 and / or housing 15.

[0081] exist Figures 1A to 2C In the example shown, the distal portion 25 of lead 16 extends upward from a position below the heart, such that the more proximal electrodes 28 and 30 are operatively close to the ventricle for receiving ventricular signals. In other examples, the distal portion 25 of lead 16 may extend downward from a position above the heart, such that the distal electrode 31 (and the intermediate electrode 30) are operatively closest to the ventricle for receiving ventricular signals. In this case, the proximal electrode 28 is operatively closest to the atrium for receiving atrial signals. Therefore, it should be understood that the example atrial sensing electrode vector and ventricular sensing electrode vector are exemplary in nature and can vary between lead and electrode configurations and between the position and orientation of the leads and electrode implants relative to the patient's heart.

[0082] Sensing circuitry 86 may include a morphological signal channel 87 for sensing cardiac electrical signals transmitted to control circuitry 80, such as multi-bit digital ECG signals, for performing morphological analysis as generally described above. Morphological signal channel 87 may receive raw cardiac electrical signals from sensing electrode vectors, which may differ from the sensing electrode vectors coupled to sensing channels 81, 83, and 85. In the illustrated example, the morphological signal sensing electrode vector includes electrode 24 and housing 15. In other examples, the morphological signal sensing electrode vector may include any of electrodes 24, 26, 28, 30, or 31 carried by leads 16 mating with housing 15. In some examples, morphological signal channel 87 may be selectively coupled to a relatively long bipolar electrode having an interelectrode distance or spacing that is relatively larger than the sensing electrode vectors coupled to sensing channel A 81, first V 83, and / or second V 85. Compared to relatively short bipolar electrodes that can be coupled to one of the other sensing channels 81, 83 or 85, the morphological sensing electrode vector coupled to the morphological signal channel 87 can provide a relatively far-field or more global cardiac signal.

[0083] The sensing electrode vectors coupled to sensing channels 81, 83, 85, and 87 can each be different sensing electrode vectors. However, in other examples, the sensing electrode vector coupled to one of sensing channels 81, 83, or 85 can be the same sensing electrode vector coupled to the shape signal channel 87. In this case, the circuitry of sensing channels 81, 83, or 85 and the shape signal channel 87 can be combined or include shared components, such that the shape signal and the Asense or Vsense signal can be output from a single sensing channel to the control circuitry 80.

[0084] Example sensing electrode vectors coupled to each sensing channel 81, 83, 85, and 87 can be obtained through... Figure 3 The switching circuit 89 shown is used to change this. The sensing electrode vector coupled to a given sensing channel can depend in part on lead 16 (see [link]). Figure 1A The relative position of the sensing electrode vector to the heart chambers can be determined and can be programmed by the user. In some examples, the sensing electrode vector selected by the switching circuit 89 coupled to a given sensing channel 81, 83, 85, or 87 can be controlled by the control circuit 80 to acquire cardiac signals, such as at least a distal vector signal, which is used by the ICD 14 in analysis for detecting lead migration. The cardiac signal sensed by a given sensing channel 81, 83, 85, or 87 for detecting lead migration can be the same as or different from the sensing electrode vector selectively coupled to the same sensing channel for sensing cardiac event signals and arrhythmia detection.

[0085] For example, electrodes 31 and 30 or electrodes 31 and 28 can be connected to a sensing channel 81 to sense cardiac electrical signals that are relatively sensitive to changes in the position of the distal electrode 31 relative to the patient's heart due to lead migration. For example, a cardiac electrical signal sensed using the distal electrode 31 may be more sensitive to changes due to lead migration than a cardiac electrical signal sensed using other available sensing electrodes. For example, when migration of the distal end 29 of the lead occurs, the cardiac electrical signal received using a sensing electrode vector including the proximal electrode 28 and housing 15 may remain relatively unchanged due to the greater stability of the position of the proximal portion of the lead 16 and / or ICD 14. However, a cardiac electrical signal received using a sensing electrode vector including the distal electrode 31 paired with any other available electrode (carried by the lead 16 or ICD housing 15) may change significantly relative to a baseline signal recorded using the same sensing electrode vector prior to lead migration.

[0086] As described herein, in some examples, control circuitry 80 can detect the migration of lead 16 by performing a comparative analysis of a first cardiac electrical signal (e.g., a distal vector signal) sensed using a first sensing electrode vector (e.g., a distal sensing electrode vector including the distal electrode 31) that is relatively sensitive to changes in the position of the distal end 29 of lead 16, with a baseline signal sensed using the same sensing electrode vector at an earlier time point prior to lead migration. Additionally or alternatively, the control circuit 80 can detect migration of the lead 16 by performing a comparative analysis of a first cardiac electrical signal (e.g., a distal vector signal) sensed using a first sensing electrode vector (e.g., a distal sensing electrode vector including a distal electrode (such as the distalmost electrode 31)) that is relatively sensitive to changes in the position of the distal end 29 of the lead 16, and a second cardiac electrical signal (e.g., a proximal vector signal) sensed using a second sensing electrode vector (e.g., a proximal sensing electrode vector including a more proximal electrode 30 or the closest electrode 28) that is relatively insensitive (or less sensitive) to changes in the position of the distal end 29 of the lead 16.

[0087] exist Figure 4In the illustrative example shown, the signals received by each sensing channel 81, 83, 85, and 87 are provided as differential input signals to pre-filters and preamplifiers 102, 62a, 62b, and 72, respectively. Non-physiological high-frequency and DC signals can be filtered by low-pass or band-pass filters included in each of the pre-filters and preamplifiers, and high-voltage signals can be removed by protection diodes included in the pre-filters and preamplifiers. Pre-filters and preamplifiers 62a, 62b, 72, and 102 can amplify the pre-filtered signals with a gain between 10 and 100, and in one example, a gain of 17, but each channel 81, 83, 85, and 87 can have different gains and filter bandwidths. Pre-filters and preamplifiers 62a, 62b, 72, and 102 can convert the differential input signals into single-ended output signals that are passed to the corresponding analog-to-digital converters (ADCs) 63a, 63b, 73, and 103. Pre-filters and pre-amplifiers 62a, 62b, 72 and 102 can provide anti-aliasing filtering and noise reduction before digitization.

[0088] As an example, ADCs 63a, ADC 63b, ADC 73, and ADC 103 can convert the corresponding first ventricular electrical signal, second ventricular electrical signal, morphological signal, and atrial electrical signal from analog signals into digital bit streams, which can be sampled at 128Hz or 256Hz. The ADC of the sensing circuit 86 can be a Σ-Δ converter (SDC), but other types of ADCs can be used. In some examples, the output of each ADC 63a, 63b, 73, and 103 can be provided to a decimator (not shown) that acts as a digital low-pass filter, increasing the resolution of the corresponding cardiac electrical signal and reducing its sampling rate.

[0089] The digital outputs of ADCs 63a, 63b, 73, and 103 can each be passed to corresponding filters 64a, 64b, 74, and 104, which can be digital bandpass filters. The bandpass filters for the corresponding sensing channels 81, 83, 85, and morphological signal channel 87 can have the same or different bandpass frequencies. For example, filters 64a and 64b can have bandpasses of approximately 10 Hz to 50 Hz or approximately 13 Hz to 39 Hz to allow R-waves, which typically occur within this frequency range, to pass through. Filter 104 for sensing channel A 81 can have the same or similar bandpass as sensing channels 83 and 85. In other examples, sensing channel A 81 can have a slightly lower bandpass, for example, 8 Hz to 32 Hz, to allow P-waves, which can have frequency content slightly lower than R-waves. As an example, filter 74 for morphological signal channel 87 can have a relatively wide bandpass of approximately 0.5 Hz to 100 Hz, 1 Hz to 100 Hz, or 2.5 Hz to 100 Hz.

[0090] In some examples, each sensing channel 81, 83, 85 and the morphological signal channel 87 may also include notch filters 107, 67a, 67b, and 76, respectively, to filter 50Hz and 60Hz noise signals. In some examples, each notch filter 107, 67a, 67b, and 76 may be individually turned on or off. The narrow-bandpass and notch-filtered signals (if the notch filter is on) in each of the two V sensing channels 83 and 85 and the A sensing channel 81 can be passed from the corresponding filter 67a, 67b, or 107 to rectifiers 65a, 65b, or 105 to produce a bandpass-filtered, rectified signal output.

[0091] In the example shown, sensing channel A 81 may include a low-pass filter 110 for receiving a band-pass filtered, rectified signal. After rectification, low-pass filter 110 may output a smoothed, rectified atrial signal 109. Sensing channel V 83 may include a low-pass filter 112 for receiving a band-pass filtered, rectified ventricular signal from rectifier 65a. Low-pass filter 112 may output a smoothed, rectified ventricular signal 69. As an example, low-pass filters 110 and 112 may be 2Hz, 3Hz, 4Hz, or 5Hz low-pass filters. Low-pass filters 110 and 112 may be infinite impulse response (IIR) filters, which may be designed to introduce minimal delay when processing the received raw atrial and ventricular signals for determining atrial and / or ventricular sensing signals, thereby facilitating real-time sensing of atrial and ventricular event signals. In other examples, low-pass filters 110 and / or 112 may be finite impulse response (FIR) filters.

[0092] A smoothed, rectified ventricular signal 69 can be transmitted from V sensing channel 83 to A sensing channel 81. A sensing channel 81 can be configured to determine atrial sensing signal 120 as a combination of atrial signal 109 and ventricular signal 69. Atrial sensing signal 120 can be determined by A sensing channel 81 by performing mathematical operations on sample point pairs from atrial signal 109 and ventricular signal 69 as operands. In the example shown, summing block 119 receives atrial signal 109 and ventricular signal 69 and outputs atrial sensing signal 120 by adding atrial signal 109 and ventricular signal 69 in out-of-phase order, obtaining atrial sensing signal 120 as the unrectified difference signal between rectified atrial signal 109 and rectified ventricular signal 69.

[0093] The atrial sensing signal 120 can be an unrectified signal, which can be passed to a low-pass filter 111 (e.g., a 3Hz to 4Hz low-pass filter) to provide a smooth, unrectified atrial sensing signal to the P-wave detector 106. As an example, the low-pass filter 111 can be a 3Hz to 4Hz IIR filter or FIR filter. The P-wave detector 106 is configured to apply a P-wave sensing threshold to the atrial sensing signal 120, which is determined from a combination of an atrial signal 109 filtered and rectified by the atrial sensing channel 81 and a ventricular signal 69 received from the ventricular sensing channel 83. In response to a P-wave sensing threshold exceeding the threshold, the A-sensing channel 81 generates an Asense signal 108, which is passed to the control circuitry 80.

[0094] The atrial sensing signal 120 can be determined by determining the sum, difference, ratio, or product of paired sample points, where each pair of sample points includes one sample point from the atrial signal 102 and one sample point from the ventricular signal 69. In other examples, paired sample points can be combined according to a nonlinear function (e.g., a logarithmic or exponential function). Paired sample points can be time-aligned sample points. In other examples, each pair of paired sample points can include a first sample point from the atrial signal 102 and a second sample point from the ventricular signal 69, the second sample point being time-shifted relative to the atrial signal sample point (e.g., one, two, or more sample points earlier or later than the atrial signal sample point).

[0095] In some examples, the atrial signal 109 from sensing channel A 81 can be passed to sensing channel V 83. Sensing channel V 83 can add the rectified ventricular signal 69 to the inverted version of the atrial signal 109 to obtain a ventricular sensing signal 122, which can be passed to a low-pass filter 124 (e.g., a 3Hz to 4Hz low-pass IIR filter or FIR filter) and then to an R-wave detector 66a. The R-wave detector 66a can apply an R-wave sensing threshold to the ventricular sensing signal 122 received from the low-pass filter 124. In response to an R-wave sensing threshold exceeding the threshold, sensing channel V 83 generates a Vsense signal 68a, which is passed to control circuitry 80.

[0096] In various examples, the ventricular sensing signal 122 can be determined by the sensing circuit 86 by determining the sum, difference, ratio, or product of paired sample points, which include one sample point from the atrial signal 102 and one sample point from the ventricular signal 69. The paired sample points can be time-aligned. In other examples, each pair of paired sample points may include one sample point from the atrial signal 102 and a second sample point from the ventricular signal 69, which is time-shifted relative to the atrial signal sample point (e.g., one, two, or more sample points earlier or later than the atrial signal sample point).

[0097] The ventricular sensing signal 122 and the atrial sensing signal 120 can each be determined by the sensing circuit 86 by performing different operations on sample point pairs obtained from the ventricular signal 69 and the atrial signal 102. In the example shown, the atrial sensing signal 120 can be determined by subtracting the ventricular signal 69 from the atrial signal 102. The ventricular sensing signal 122 can be determined by subtracting the atrial signal 102 from the ventricular signal 69. In other examples, the atrial sensing signal 120 can be determined as the ratio of the atrial signal 102 to the ventricular signal 69, and the ventricular sensing signal 122 can be determined as the ratio of the ventricular signal 69 to the atrial signal 102. In other examples, the atrial sensing signal 120 can be determined using a first operation (e.g., addition) performed on operands (sample points) obtained from the atrial signal 102 and the ventricular signal 69, and the ventricular sensing signal 122 can be determined using different second operations (e.g., subtraction, division, or multiplication) performed on operands obtained from the atrial signal 102 and the ventricular signal 69.

[0098] exist Figure 4 In the example shown, the second V-sensing channel 85 can transmit the rectified ventricular signal output from rectifier 65b to R-wave detector 66b. The second V-sensing channel 85 can apply an R-wave sensing threshold to the received rectified ventricular signal, which can be controlled separately from the R-wave sensing threshold controlled by R-wave detector 66a. In response to an R-wave sensing threshold exceeding the limit caused by the rectified ventricular signal, the second V-sensing channel 85 can generate a V-sense signal 68b, which can be transmitted to control circuitry 80. In other examples, when the second V-sensing channel 85 is included, the V-sensing channel 85 can receive a rectified atrial signal 109 for use in any of the methods described above for combining atrial and ventricular signals to determine a second ventricular sensing signal. The second ventricular sensing signal determined using atrial signal 109 can be transmitted to R-wave detector 66b for sensing R-waves.

[0099] P-wave detector 106 and R-wave detectors 66a and 66b may each include an automatically adjusting sensing amplifier, comparator, and / or other detection circuitry that compares an incoming signal to a sensing threshold and generates a sensed cardiac event signal (e.g., Asense event signal 108, Vsense signal 68a, or Vsense signal 68b) when the corresponding signal crosses the corresponding sensing threshold. The corresponding sensing threshold may be outside any blanking period applied by the sensing circuitry (e.g., post-pacing blanking period, post-sensing blanking period, atrial-to-ventricular blanking period applied by R-wave detectors 66a and 66b, or atrial-to-ventricular blanking period applied by P-wave detector 106).

[0100] The P-wave sensing threshold applied to the incoming atrial sensing signal by the P-wave detector 106 can be a fixed threshold, such as a programmed value, or determined by the control circuit 80 based on the average or median maximum peak amplitude of previously sensed P waves. In other examples, the P-wave sensing threshold can be a multi-level or decreasing threshold that can decrease from an initial value to a sensing limit. The initial value can be set as a percentage of the maximum peak amplitude of one or more recently sensed P waves. The sensing limit or minimum value can correspond to a programmed atrial sensitivity. The P-wave sensing threshold can decrease from the initial value to the sensing limit based on one or more step decreases and / or decay rates.

[0101] The R-wave sensing threshold applied to the incoming ventricular sensing signal or ventricular signal by R-wave detectors 66a and 66b can be a fixed threshold, such as a programmed value, or determined by control circuitry 80 based on the average or median maximum peak amplitude of the R waves previously sensed by each corresponding V-sensing channel 83 and 85. In other examples, the R-wave sensing threshold can be a multi-stage or generally decreasing threshold, each decreasing from an initial value to a sensing limit. The initial value can be set as a percentage of the maximum peak amplitude of one or more recently sensed R waves. The sensing limit or minimum value can correspond to a programmed ventricular sensitivity. The R-wave sensing threshold can decrease from the initial value to the sensing limit based on one or more step decreases (which can occur at specified fall intervals) and / or decay rates (within one or more decay intervals). The R-wave sensing threshold used by R-wave detectors 66a and 66b can be individually controlled according to different R-wave sensing threshold control parameters.

[0102] The broadband-filtered digital cardiac electrical signal 78 output from the morphological signal channel 87 can be passed to the control circuit 80 for morphological analysis when arrhythmia detection by the control circuit 80 is required. In some examples, the digital cardiac electrical signal 78 is passed to a rectifier 75, and the rectified broadband-filtered signal 79 is passed to the control circuit 80 for processing and analysis. In some cases, both the filtered unrectified signal 78 and the rectified signal 79 are passed from the morphological signal channel 87 to the control circuit 80 to determine the morphological characteristics of the ECG signal.

[0103] In some examples, unrectified, broadband-filtered signal 78 or rectified signal 79 from morphological signal channel 87 can be analyzed by control circuitry 80 for lead migration detection. In some examples, changes in the P wave sensed by sensing channel 81 (e.g., changes in P wave amplitude or morphology, suspected undersensitization of the P wave, or suspected oversensitization of the P wave) can trigger analysis of the broadband-filtered signal 78 by control circuitry 80. For example, unrectified, broadband-filtered signal 78 can be analyzed to obtain changes in the polarity and / or amplitude of cardiac event signals (e.g., P wave, QRS waveform, and / or T wave) in signal 78. To detect changes in the polarity and / or amplitude of the QRS waveform that may be due to lead migration, switching circuitry 89 can be configured to couple a distal sensing electrode vector to morphological sensing channel 87. The distal sensing electrode vector may include the distal electrode 31 combined with another electrode (e.g., the nearest electrode 28), but other electrodes or housing 15 may be paired with the distal electrode 31. The distal vector signal, including the distal electrode 31, is likely to be most sensitive to changes caused by lead migration. However, it is conceivable that the distal vector signal may not necessarily include the distal electrode of the medical electrical lead. Depending on the lead and electrode configuration, the sensing electrode vector used to sense the distal vector signal used in detecting lead migration may include an electrode that is typically located along the distal portion of the medical electrical lead and may be relatively closer to the distal end of the lead than to the proximal end.

[0104] Combined with Figure 8 and Figure 9 Examples of changes in the polarity and / or amplitude of the cardiac event signal waveform are described, which may occur with lead migration and may be detectable by control circuitry 80 as evidence of lead migration. As previously mentioned, the electrodes selected to be coupled to one or more of sensing channels 81, 83, 85 and / or 87 to obtain signals for detecting lead migration may be different from the electrodes coupled to one or more of sensing channels 81, 83, 85 and / or 87 to obtain signals for sensing cardiac event signals and performing morphological analysis to detect arrhythmias.

[0105] like Figure 4The configuration of sensing channels 81, 83, and 85 and the morphological signal channel 87 shown is essentially illustrative. Sensing circuitry 86 may include... Figure 4 The examples illustrate more or fewer components, and some components may be shared between sensing channels 81, 83, and 85 and morphological signal channel 87. For example, a common cardiac electrical signal from a selected sensing electrode vector may be received by a pre-filter and pre-amplifier circuit and an ADC, and then passed to a narrowband filter in one of sensing channels 83 or 85 and a wideband filter in morphological signal channel 87. In other examples, sensing circuit 86 may include two sensing channels 81 and 83, and the wideband-filtered morphological signal may be passed from one of sensing channels 81 or 83 to control circuit 80. Furthermore, components for filtering, amplification, digitization, rectification, etc., may be shared with... Figure 4 Different sequences or combinations are shown to arrange the components, and some components can be shared between sensing channels 81, 83, 85 and morphological signal channel 87.

[0106] Figure 5 This is a conceptual diagram 200 that can be used to detect electrophysiological signals related to lead migration. Figure 5 In the example, the electrophysiological signals include atrial sensing signal 206 and ventricular sensing signal 216, which, according to some examples, can be generated by... Figure 4 The A-sensing channel 81 and V-sensing channel 83 are determined. Signal 202 may be a signal received by the atrial sensing channel 202 after bandpass filtering and amplification. Signal 202 may be passed to rectifier 105 and low-pass filtered to produce a rectified smooth atrial signal 204. Atrial signal 204 and ventricular signal 214 (described below) may be combined according to one or more operations performed on paired sample points of atrial signal 204 and ventricular signal 214 to determine atrial sensing signal 206 by sensing circuit 86. In the example shown, atrial sensing signal 206 represents the difference signal obtained by A-sensing channel 81 by subtracting the smoothed, rectified ventricular signal 214 received from V-sensing channel 83 from the smoothed, rectified atrial signal 204. P-wave detector 106 may apply P-wave sensing threshold 208 to the unrectified atrial sensing signal 206. Asense event signal 210 can be generated by A sensing channel 81 in response to a P-wave sensing threshold exceeding the limit caused by atrial sensing signal 206.

[0107] Signal 212 can be received by V sensing channel 83. Signal 212 represents a bandpass-filtered and amplified signal, which can be passed to rectifier 65a and low-pass filtered to produce a smooth, rectified ventricular signal 214. The ventricular signal 214 and the atrial signal 204 can be combined based on one or more operations performed on paired sample points of the ventricular signal 214 and the atrial signal 204 to determine the ventricular sensing signal 216. The ventricular sensing signal 216 can be obtained by V sensing channel 83 by subtracting the rectified atrial signal 204 received from A sensing channel 83 from the rectified ventricular signal 214 and passing the resulting unrectified difference signal through a low-pass filter. R-wave detector 66a can apply an R-wave sensing threshold 218 to the unrectified ventricular sensing signal 216. Vsense signal 220 can be generated by V sensing channel 83 in response to an R-wave sensing threshold exceeding the limit caused by the unrectified ventricular sensing signal 216.

[0108] Combined with the following text Figure 6 and Figure 7 As described in the flowchart, control circuit 80 can analyze one or more of the following obtained by sensing circuit 86 using the distal electrode 31 of lead 16 paired with another available electrode in the distal sensing electrode vector: unrectified atrial signal 202, smoothed rectified atrial signal 204, and atrial sensing signal 206. Control circuit 80 can detect migration of the distal end 29 of lead 16 based on analysis of one or more of the signals 202, 204, and / or 206 obtained at a baseline time point and a later time point, in order to detect changes in the signal obtained using the distal electrode 31 that may indicate lead migration.

[0109] In some examples, control circuitry 80 may use the proximal sensing electrode vector, excluding the distal electrode 31 of lead 16, to analyze one or more of the unrectified ventricular signal 212, the smoothed rectified ventricular signal 214, and / or the ventricular sensing signal 216 obtained by sensing circuitry 86. Control circuitry 80 may detect migration of the distal end 29 of lead 16 based on analysis of one or more of signals 212, 214, and / or 216 combined with one of signals 202, 204, and / or 206 obtained at a baseline time point and a later time point, to detect changes in the signal obtained using distal electrode 31 that may indicate lead migration while signals 212 and / or 214 remain relatively constant. For example, a threshold change (e.g., at least) of the maximum peak amplitude 230 of signal 204 obtained during lead migration detection relative to the baseline maximum peak amplitude of the smoothed, rectified atrial signal 204. +(20% or more) can be an indication of migration of the distal end 29 of lead 16. A threshold change in the maximum peak amplitude 234 of the atrial sensing signal 234 relative to the maximum peak amplitude of the atrial sensing signal obtained at the baseline time point can be evidence of migration of the distal end 29 of lead 16.

[0110] A threshold change in the maximum peak amplitude 230 of the atrial signal 204, combined with a threshold change in the maximum peak amplitude 232 of the ventricular signal 214, could be evidence of distal lead migration. A threshold change in the difference between the maximum peak amplitude 230 and the maximum peak amplitude 232 determined during lead migration testing, relative to the difference between the maximum peak amplitudes of the atrial signal 204 and the ventricular signal 214 determined at baseline, could also be evidence of distal lead migration.

[0111] In some examples, changes in the atrial signal 206 that occur when the ventricular signal 216 remains relatively constant can be detected by comparing one or more features of the atrial sensing signal 204 and / or the ventricular sensing signal 214 determined during the lead migration check time point with similar features determined at the baseline time point. For example, a threshold change in the maximum peak amplitude 234 or the maximum peak amplitude 236 compared to the corresponding baseline maximum peak amplitude can be identified as evidence of distal lead migration. In some examples, threshold changes in the maximum peak amplitude 234 of the P wave, the maximum peak amplitude 236 of the R wave, and / or the quantitative relationship between the maximum peak amplitudes 234 and 236 can be detected by control circuitry 80 as a trigger for performing cardiac signal analysis to detect lead migration.

[0112] Figure 6 This is a flowchart 300 illustrating, based on some examples, a method for detecting lead migration that can be performed by a medical device. (Reference) Figures 1A to 4 The concept of ICD 14 is used to describe... Figure 6And other flowcharts and illustrations presented herein. However, it should be understood that other IMDs configured to sense electrophysiological signals via medical electrical leads extending from a medical device can be configured to perform the techniques disclosed herein for detecting migration of medical electrical leads based on features determined from electrophysiological signals, which may include detecting electrical event signals from the sensed electrophysiological signals. Furthermore, it is conceivable that cardiac electrical signals sensed by an IMD (such as ICD 14) can be transmitted to an external device (e.g., external device 40) for processing and analysis by an external device processor 52 to detect lead migration. Thus, it should be understood that control circuitry performing the techniques disclosed herein for detecting lead migration and generating output in response to detected lead migration may be included in an external medical device configured to receive cardiac electrical signals sensed by an IMD. In some examples, the processing and analysis for detecting lead migration may be cooperatively performed by processing circuitry included in the IMD and external device 40 according to computer-readable instructions stored in the memory of the IMD and external device 40.

[0113] At block 301, control circuitry 80 may determine and store one or more baseline features of the cardiac electrical signal sensed using the distal sensing electrode vector. The cardiac electrical signal sensed using the distal sensing electrode vector is referred to herein as the “distal vector signal.” The distal sensing electrode vector may include the distal electrode 31 carried by a lead 16 connected to the ICD 14. In one example, the distal sensing electrode vector may include the distal electrode 31 and a ring electrode 30 (the next distal electrode along the distal portion 25 of the lead 16). In other examples, the distal sensing electrode vector may include the distal electrode 31 paired with a coil electrode 26, a coil electrode 24, a ring electrode 28, or a housing 15.

[0114] The cardiac electrical signal sensed using the distal electrode 31, which is closest to the free distal end 29 of lead 16, may be most susceptible to changes caused by migration of the distal end 29 of lead 16. Migration can be toward or away from the heart, for example, closer to or further away from the atrial ventricle. Therefore, starting from the baseline time point, the control circuit 80 can monitor changes in the distal vector signal sensed using the distal electrode 31 over time to detect lead migration. In some cases, when the free distal end 29 migrates, the two distal electrodes (e.g., Figure 1AElectrodes 30 and 31 shown can be repositioned relative to the patient's heart such that even if the distal end 29 of lead 16 has migrated, the angle of the sensing vector along which it senses cardiac electrical signals relative to the cardiac axis does not change significantly. When the distal sensing electrode vector includes the distal electrode 31 and the proximal electrode 28 or ICD housing 15, the angle of the sensing vector along which it senses cardiac electrical signals (e.g., relative to the cardiac axis) can change more significantly, and it can remain in a relatively stable position during lead migration. Thus, in some cases, changes in cardiac electrical signals due to lead migration can be more easily detected from the distal vector signal sensed using the distal electrode 31 and the proximal electrode 28 or ICD housing 15.

[0115] At block 302, control circuitry 80 can determine the baseline characteristics of the distal vector signal at a baseline time point. The baseline time point can be the implantation time of lead 16. However, it is conceivable that the baseline characteristics of the distal vector signal can be determined (or redefined) at any selected baseline time point, either at or after implantation, for the purpose of detecting migration of lead 16 relative to its position at that selected baseline time point. (Reference) Figure 4 The control circuit 80 can receive a smoothed, rectified atrial signal 109 (e.g., Figure 5 The signal (shown as signal 204) is a distal vector signal sensed by sensing channel A using distal electrode 31. At block 302, control circuitry 80 can determine one or more features of the smoothed, rectified atrial signal 109 as baseline features. In other examples, control circuitry 80 can receive atrial sensing signal 120 (before or after low-pass filtering by filter 111) as a distal vector signal, which can be determined as a combination of atrial signal 109 and ventricular signal 69. At block 302, control circuitry 80 can determine the atrial sensing signal 120 (before or after low-pass filtering by filter 111) as a distal vector signal, which can be determined as a combination of atrial signal 109 and ventricular signal 69. Figure 4 One or more baseline features of the signal (shown as signal 206) are identified as features of the far-side vector signal.

[0116] In an exemplary example, the P-wave detector 106 of sensing channel A 81 can receive unrectified atrial sensing signals, for example... Figure 5The signal 206 is shown. The P-wave detector 106 can determine the maximum peak amplitude 230 after each P-wave sensing threshold is exceeded and transmits the maximum peak amplitude 230 to the control circuit 80. The control circuit 80 can determine the baseline distal vector signal characteristics as the average, median, or other representative value of a specified number of received maximum peak amplitudes (e.g., 5 to 100 maximum peak amplitudes) of the sensed atrial event signal. Furthermore, it is conceivable that the baseline distal vector signal characteristics could be representative values ​​of signal characteristics determined from the distal vector signal at multiple time points spanning an hour, a day, a week, or other relatively long time periods (as opposed to characteristics determined from one or several heartbeats) to remove potentially inherent physiological variability in the distal vector signal. For example, the control circuit 80 can record the distal vector signal characteristic values ​​in a histogram in memory 82 to enable statistical analysis of the histogram values ​​sampled over relatively long time periods (such as an hour, twelve hours, a day, or a week). Therefore, a baseline time point can be a time point spanning a period of time during which at least one baseline feature of the distal vector signal can be determined to establish a representative value for the baseline feature. The baseline time point can span several minutes, hours, days, weeks, or other selected time periods during which cardiac signal data is collected to establish baseline feature values. It should be recognized that many signal features can be determined to characterize the baseline distal vector signal, such as, but not limited to, slope, area, peak amplitude, peak polarity, mean amplitude of all sample points across the segment of the distal vector signal, normalized rectified amplitude of all sample points across the segment of the distal vector signal, or other signal features representing or characterizing the distal vector signal at the baseline time point. In some examples, the ratio, difference, or other quantitative relationship between the maximum positive peak amplitude and the maximum negative peak amplitude can be determined (e.g., in conjunction with the following). Figures 8A to 8C (as described).

[0117] In other examples, any of the example distal sensing electrode vectors listed herein can be used (e.g., the distal electrode 31 paired with electrode 24, electrode 26, electrode 28, electrode 30, or housing 15 (see [link to documentation]). Figure 1A The distal vector signal is sensed using morphological signal channel 87, for example, by using electrodes 31 and 28. In some examples, the distal vector signal is a rectified or unrectified broadband filtered signal and can be acquired by morphological signal channel 87, for example, using electrodes 31 and 28. For convenience, Figure 6This is described as a process for analyzing a distal vector signal. In some examples, multiple distal vector signals can be analyzed to detect changes in the distal vector signal indicating lead migration. For example, a distal vector signal can be sensed using the distal electrode 31 and the proximal electrode 28, and a second distal vector signal can be sensed using the distal electrode 31 and the housing 15. Two distal vector signals can be analyzed to detect changes due to lead migration, which can be caused by a change in the direction or angle of at least one of the distal sensing electrode vectors relative to the patient's heart due to lead migration. See below in conjunction with Figure 8 and... Figure 9 The relative change in the distal vector signal between the baseline time point and a later time point, as discussed, can depend on the migration direction of the free distal end 29 of lead 16 and / or the change in the angle between the distal sensing electrode vector and the cardiac axis from the baseline time point to a later time point. In some cases, a distal vector signal can change to a greater extent than a second distal vector signal (or a proximal vector signal, as discussed below).

[0118] At block 304, control circuitry 80 can determine when it is time to perform a lead migration check. Lead migration checks can be performed daily, weekly, monthly, or on a planned basis. Additionally or alternatively, lead migration checks can be performed on a triggered basis in response to changes in pacing capture thresholds, changes in lead impedance measurements, detection of potential undersensitivity of P waves and / or R waves, detection of oversensitivity of P waves and / or R waves, or after delivery of a high-voltage CV / DF shock. If P waves and R waves are not sensed in a 1:1 ratio, undersensitivity or oversensitivity of P waves or R waves may be suspected. If the maximum peak amplitude of the sensed signal is close to the P wave sensing threshold amplitude when the atrial sensing event signal is detected, undersensitivity or oversensitivity of P waves may be suspected. For example, low-amplitude P waves may be undersensitized when some P waves with peak amplitudes just above the P wave sensing threshold are being sensed. In other cases, such as those caused by skeletal muscle myoelectric potentials (SMEPs) with amplitudes close to the programmed atrial sensitivity, relatively high-amplitude noise pulses may be oversensed as P waves. If the maximum peak amplitude of the sensed ventricular event signal is close to the R-wave sensing threshold amplitude at the time the ventricular event signal is sensed, undersensing or oversensing of R waves can be suspected. For example, low-amplitude R waves may be undersensed when sensing some R waves with peak amplitudes just above the R-wave sensing threshold. In other cases, such as those caused by skeletal muscle myoelectric potentials (SMEPs) with amplitudes close to the programmed ventricular sensitivity, relatively high-amplitude noise pulses may be oversensed as R waves.

[0119] When the amplitude, cardiac event interval (such as PPI or RRI), or other characteristics of continuously sensed cardiac event signals exhibit alternating patterns, it may be suspected that P waves are oversensed as spurious R waves, T waves are oversensed as spurious R waves, or R waves are oversensed as spurious P waves. PWOS can be detected on sensing channels V 83 or 85 based on alternating peak amplitudes following an R wave sensing threshold exceedance, where alternating low-amplitude peaks temporally correspond to P wave sensing threshold exceedances in sensing channel A 81. R wave oversensing can also be detected on sensing channel A 81 by detecting alternating peak amplitudes following a P wave sensing threshold exceedance, where every other P wave sensing threshold exceedance temporally corresponds to an R wave sensing threshold exceedance in sensing channels V 81 or 83.

[0120] Additionally or alternatively, when one or more pairs of Asense and Vsense signals are received nearly simultaneously or within each other's suspected oversensing time intervals, the control circuit 80 may detect suspected oversensing on the A sensing channel 81 and / or the V sensing channel 83. Additionally or alternatively, when the VT / VF interval counter reaches a threshold for one or both of the V sensing channels 83 and / or 85, the control circuit 80 may detect suspected P-wave oversensing of the A sensing channel 83 or 85. Additionally or alternatively, when the atrial tachyarrhythmia interval counter reaches a threshold, the control circuit 80 may detect suspected R-wave oversensing by the A sensing channel 81. The control circuit 80 may perform further analyses to detect suspected undersensing or oversensing of cardiac event signals from the sensed cardiac electrical signals, for triggering lead migration checks. Other analyses may include, for example, analysis of slope content (e.g., low slope content), peak amplitude analysis, pulse width analysis, and / or other methods for detecting suspected oversensing and / or undersensing may be used to trigger lead migration checks. Various methods for detecting oversensing of cardiac event signals can be implemented in a medical device configured to detect lead migration according to the techniques disclosed herein, and can be used to trigger lead migration checks. Some example methods for detecting oversensing of cardiac events that can be used in conjunction with the lead migration detection techniques disclosed herein are generally disclosed in U.S. Patent Nos. 9,597,525 (Cao et al., filed May 6, 2015) and 11,135,441 (Zhang et al., filed June 24, 2019), the entire contents of which are incorporated herein by reference.

[0121] When control circuit 80 determines at block 304 that it is time to perform a lead migration check, control circuit 80 may re-determine the distal vector signal characteristics previously determined from the distal vector signal at the baseline time point at block 306. At block 308, control circuit 80 may perform a comparative analysis of the new distal vector signal characteristics and the baseline characteristics. For example, control circuit 80 may determine whether the difference between a given baseline characteristic and the corresponding new characteristic is greater than a threshold. Depending on the direction of lead migration 16, the threshold change may be negative or positive. Therefore, control circuit 80 may compare the absolute value of the difference between the baseline characteristic value and the new characteristic value with the threshold. In other examples, control circuit 80 may compare the new characteristic value with a threshold range that extends greater than and less than the baseline characteristic value. The threshold or range used by control circuit 80 may depend on the specific characteristic being determined, the initial baseline value of the characteristic, and / or other factors. For example, a threshold or range may be selected to facilitate the detection of lead migration that may lead to incorrect sensing of cardiac electrical signals and / or changes in pacing capture thresholds. The threshold or range may be determined by control circuit 80 as a percentage of the baseline characteristic value.

[0122] In some examples, the far-side vector signal features can be buffered in the histogram, for example, on an hourly or daily basis, so that when a lead migration check is performed, statistical analysis of the histogram values ​​can be performed to compare them with a baseline histogram analysis. For example, the median or mode of the histogram values ​​buffered in memory 82 during the baseline time period can be compared with the median or mode of the histogram values ​​buffered in memory 82 during a later lead migration check time period.

[0123] If the new feature of the distal vector signal does not indicate a threshold change from the baseline feature value, the control circuit 80 can return to block 304 to wait for the next planned or triggered lead migration check. When the new feature value of the distal vector signal indicates a threshold change from the baseline feature value, the control circuit 80 can detect lead migration or suspected lead migration and execute a lead migration detection response at block 310.

[0124] Lead migration detection response may include storing data that can be transmitted by telemetry circuitry 88 in memory 82. The stored data may include lead migration detection alarms, new eigenvalues ​​of the distal vector signal determined during lead migration checks, and / or episodes of the distal vector signal recorded concurrently with the lead migration check. In some examples, the stored data may include cardiac signal segments and / or features determined from other cardiac electrical signals sensed by sensing circuitry 86 using other sensing electrode vectors, to provide a comparison between different sensing electrode vectors that can be used by sensing circuitry 86 to sense cardiac event signals.

[0125] Control circuitry 80 may control telemetry circuitry 88 to transmit data stored in memory 82 as part of a response performed at block 310. The transmitted data may include baseline characteristic values ​​(previously stored in memory 82), characteristic values ​​determined during a previous lead migration check (previously stored in memory 82), and / or new characteristic values ​​of the distal vector signal determined during the current lead migration check. The transmitted data may include segments of the distal vector signal stored at the baseline time point during the current lead migration check, and may include segments of the distal vector signal stored during one or more intermediate lead migration checks. In some examples, the transmitted data may include segments of one or more cardiac electrical signals sensed by sensing circuitry 86 using one or more other sensing electrode vectors.

[0126] External device 40 ( Figure 1A The external device 40 can receive transmitted distal vector signal segments recorded at the baseline time point and the current lead migration detection time point, which can be displayed on the display unit 54 for clinician review. In some examples, distal vector signal segments recorded at one or more intermediate lead migration detection time points (after the baseline time point but before the suspected lead migration detection) can be received and displayed by the external device 40 for clinician review. Any other cardiac electrical signal segments recorded and transmitted by the ICD 14 in response to a suspected lead migration detection can be received and displayed by the external device 40. Clinicians can review other cardiac electrical signal segments to provide information useful in reprogramming the sensing electrode vectors, such as based on P wave amplitude, R wave amplitude, baseline noise amplitude, etc. In some examples, as a supplement to or alternative to transmitting and displaying cardiac signal segments, cardiac signal characteristics may be determined by control circuitry 80 from one or more other cardiac signals sensed by distal vector signals and / or using other available atrial signal sensing electrode vectors and / or ventricular signal sensing electrode vectors, stored in memory 82, and transmitted by telemetry circuitry 88 for reception and display by external device 40.

[0127] The response to lead migration detection performed by control circuitry 80 at block 310 may include adjusting cardiac event sensing control parameters used by sensing circuitry 86 when sensing cardiac signals and detecting cardiac event signals. In some examples, adjusting the cardiac event sensing control parameters may include (e.g., by switching circuitry 89) selecting different sensing electrode vectors for coupling to sensing channel A 81, to one or both of sensing channels V 83 and 85, and / or to morphological signal sensing channel 87. Different sensing electrode vectors may be selected to connect to one or more sensing channels 81, 83, 85, and 87 to promote a higher signal intensity of the desired cardiac event signal (e.g., a higher R-wave amplitude in the ventricular signal or a higher P-wave amplitude in the atrial signal). Different sensing electrode vectors may be selected to connect to one or more sensing channels 81, 83, 85, and 87 to promote improved signal quality with a lower noise amplitude, for example, when lead migration causes an increased skeletal muscle noise pulse amplitude that results in oversensing of the P-wave or R-wave in the signal of a given sensing electrode vector.

[0128] Different sensing electrode vectors can be selected to connect to sensing channel A 81 to reduce the likelihood of sensing channel A 81 oversensing R waves, T waves, and / or skeletal muscle noise. For example, if the peak amplitude of the R wave and / or T wave has increased in the distal sensing vector signal due to lead migration, the electrode of the atrial sensing electrode vector may have migrated closer to the ventricular chamber or to a region of higher skeletal muscle potential activity. A new atrial sensing electrode vector can be selected that is now operatively closer to the atrial chamber (or now further away from the ventricular chamber and / or skeletal muscle) than the original atrial sensing electrode vector that may have migrated further away from the atrial chamber. In some cases, such as if the distal end 29 has migrated too far from the atrial chamber to sense the atrial signal for reliable P wave sensing, and another atrial sensing electrode vector is not identified or unavailable for reliable P wave sensing, sensing channel A 81 can be de-energized or disabled. The control circuit 80 can be switched to single-chamber ventricular sensing for sensing R waves, detecting ventricular arrhythmias, and controlling the delivery of cardiac electrical stimulation pulses generated by the treatment delivery circuit 84.

[0129] In some examples, the response performed at box 310 may include selecting a different sensing electrode vector to connect to one or both of V sensing channels 83 and 85 to reduce the likelihood of P wave oversensing in the corresponding V sensing channel 83 or 85. For example, if the peak P wave amplitude has decreased in the distal sensing vector signal due to lead migration, the P wave amplitude in the ventricular sensing electrode vector may have increased because the ventricular sensing electrode vector is closer to the atrial chamber, resulting in P wave oversensing. A new ventricular sensing electrode vector may be selected that is now operatively closer to the ventricular chamber (or now farther from the atrial chamber) than the original ventricular sensing electrode vector, which may have migrated to a position closer to the atrial chamber (or more generally, farther from the ventricular chamber).

[0130] The process of selecting a new sensing electrode vector for one or more sensing channels 81, 83, 85, or 87 connected to sensing circuit 86 can be performed by control circuit 80 at block 310 and may include analysis of one or more cardiac electrical signals sensed using different available sensing electrode vectors. The ratio between the sensed peak amplitude of a ventricular event and the sensed peak amplitude of an atrial event can be determined and used to select the ventricular and atrial sensing electrode vectors. In some examples, the ratio between the sensed peak amplitude of a cardiac event (atrium or ventricle) and the peak amplitude of a signal-to-noise pulse can be determined as a signal quality metric. For example, the peak amplitude of a signal-to-noise pulse can be determined by control circuit 80 as a signal-to-noise ratio metric during cardiac electrical signal segments extending before and after the sensed cardiac event. Control circuit 80 can select a new sensing electrode vector with a high signal-to-noise ratio metric (e.g., a relatively high ratio of cardiac event signal amplitude to low signal-to-noise pulse amplitude). A method for determining muscle noise pulse counts in a cardiac signal segment, which can be implemented in conjunction with the methods disclosed herein, is generally disclosed in U.S. Patent No. 10,750,970 (Stadler et al.), filed December 17, 2018, the entire contents of which are incorporated herein by reference. The muscle noise pulse count can be determined by control circuitry 80 as a signal quality metric. When the current atrial or ventricular sensing electrode vector causes a relatively high muscle noise pulse count, the sensing electrode vector causing a lower muscle noise pulse count can be identified and selected by control circuitry 80 as a new sensing electrode vector. At block 310, control circuitry 80 can determine one or more signal strength or signal quality metrics for selecting a new atrial sensing electrode vector and / or a new ventricular sensing electrode vector in response to the detection of lead migration. Examples of signal quality metrics that can be identified for selecting a new sensing electrode vector in response to the detection of lead migration are generally disclosed in U.S. Patent Nos. 7,496,409 (filed February 24, 2009 by Greenhut et al.) and 7,904,153 (filed March 8, 2011 by Greenhut et al.), the entire contents of which are incorporated herein by reference.

[0131] Adjusting sensing control parameters in response to lead migration detection performed by control circuitry 80 at block 310 may include adjusting cardiac event sensing control parameters. Control circuitry 80 may adjust the sensing control parameters accordingly when the cardiac event amplitude increases or decreases in a given sensing channel due to lead migration. Control circuitry 80 may adjust the sensing control parameters to effectively increase or decrease cardiac event sensing thresholds, such as P-wave sensing thresholds or R-wave sensing thresholds. Various control parameters that may be increased or decreased may include atrial sensitivity, ventricular sensitivity, a percentage of the maximum peak amplitude of the sensed event signal used to set the initial sensing threshold amplitude, a percentage of the maximum peak amplitude of the sensed event signal used to set the intermediate sensing threshold amplitude, the decay rate of the sensing threshold amplitude, the decay time of the sensing threshold amplitude, the fall interval during which the sensing threshold decreases in steps, and / or the step decrease applied to the sensing threshold amplitude when the fall interval expires.

[0132] The response to lead migration detection performed by control circuitry 80 at block 310 may include adjusting arrhythmia detection control parameters. These arrhythmia detection control parameters may be used by a rapid arrhythmia detection algorithm, for example, performed by arrhythmia detection circuitry 92. In some examples, the arrhythmia detection control parameters may be adjusted to effectively extend the time required to detect VT / VF. Oversensing can lead to false detections of VT / VF when lead migration is detected. Control circuitry 80 may increase the NID required to detect VT / VF to reduce the likelihood of false VT / VF detections due to oversensing signals. In some arrhythmia detection algorithms, a threshold number of rapid arrhythmia intervals may enable control circuitry 80 to activate morphological sensing channel 87 to begin receiving morphological signals for buffering morphological signal segments in memory 82. Arrhythmia detection circuitry 92 may perform various signal morphology analysis methods to confirm or reject VT / VF detection upon reaching the NID. When lead migration is detected, control circuitry 80 may delay enabling morphological sensing channel 87 and / or performing morphological analysis, which may require significant processing power to avoid increasing current consumption from power supply 98 in case of potential oversensing. For example, control circuitry 80 may increase the threshold number of VT / VF intervals required to energize morphological sensing channel 87 for buffering cardiac signal segments in memory 82. Control circuitry 80 may also increase the threshold number of VT / VF intervals required to initiate cardiac signal segment morphological analysis performed by control circuitry 80 for detecting arrhythmias.

[0133] The response to lead migration detection performed at block 310 may include treatment delivery adjustment. Treatment delivery adjustment may include performing a pacing capture test to verify ventricular capture via pacing pulses delivered by a ventricular pacing electrode vector. The pacing capture test may include delivering one or more pacing pulses with the current pacing pulse output (e.g., pulse amplitude, pulse width, and number of stacked pulses when delivering a composite pacing pulse of two or more individual pulses to capture the ventricle). If a loss of capture is determined (e.g., based on no evoked response signal sensed after the pacing pulse), control circuitry 80 may control treatment delivery circuitry 84 to perform a capture threshold test to determine the pacing pulse output required to capture the ventricle. Treatment delivery adjustment may include adjusting the pacing pulse output to facilitate ventricular capture during pacing therapy (e.g., atrial-synchronized ventricular pacing, bradycardia or cardiac arrest pacing, ATP, post-shock pacing, etc.). Treatment delivery adjustment may include adjusting the treatment delivery vector, such as the pacing electrode vector and / or the CV / DF shock delivery vector. Treatment delivery adjustments may include adjusting (e.g., increasing) the CV / DF shock energy to facilitate successful termination of detected ventricular tachyarrhythmias when lead migration has already occurred.

[0134] Treatment delivery adjustments may include disabling pacing therapy. As a non-limiting example, pacing therapy that can be disabled may be one or more of atrial synchronized ventricular pacing, bradycardia pacing, and / or ATP. Pacing therapy may be disabled when lead migration is detected because lead migration can lead to unreliable sensing and / or unreliable capture by the delivered pacing pulse and / or extrinsic stimulation of skeletal muscle caused by the cardiac pacing pulse.

[0135] Figure 7 This is a flowchart 400 of a method for detecting lead migration, which can be performed by a medical device, according to another example. In conjunction with... Figure 6 In the described example method, control circuitry 80 can detect lead migration based on a comparative analysis of at least one distal vector signal obtained at the lead migration inspection time point and a corresponding distal vector signal obtained at the baseline time point. Figure 7 In the example, the difference between the distal vector signal and the proximal vector signal can be determined at a baseline time point and at a subsequent lead migration inspection time point. Control circuitry 80 can detect lead migration (or suspected lead migration) based on the change in the difference between the distal and proximal vector signals at the lead migration inspection time point relative to the difference between these two signals at the baseline time point. The proximal portion of lead 16 may migrate less than the distal end 29 of lead 16 (see...). Figure 1AThus, it can be expected that, excluding the sensing electrode vector of the distal sensing electrode 31, the change in cardiac electrical signal due to lead migration in the cardiac electrical signal sensed using the distal sensing electrode will be greater than that sensed using the proximal sensing electrode. In some cases, when the proximal vector signal changes very little or not at all, the control circuit 80 can detect lead migration based on a threshold change in at least one distal vector signal. However, in other cases, such as in combination Figure 9 The discussion focuses on how changes in the proximal vector signal can indicate lead migration in a specific direction when the distal vector signal changes very little or not at all, such as lead 16 retraction relative to the patient's heart in a downward or approximately caudal direction.

[0136] In some cases, due to lead migration, the proximal vector signal may change less or more than the distal vector signal. By analyzing changes in the relative differences between characteristics of the distal vector signal and similar characteristics of the proximal vector signal, erroneous lead migration detection due to changes in the distal and / or proximal vector signals caused by factors other than lead migration can be avoided. For example, changes in patient posture, patient body movement, environmental noise, or other factors may cause changes in the distal vector signal that are unrelated to lead migration during lead migration testing. Such changes can be expected to affect or alter both the distal and proximal vector signals.

[0137] At block 402, control circuit 80 can determine and store baseline signal characteristics and / or signal differences determined from the distal vector signal and the proximal vector signal. (Based on the above...) Figure 6 In any of the examples described, control circuitry 80 can acquire the distal vector signal and determine one or more baseline characteristics of the distal vector signal at a baseline time point. Segments of the distal vector signal at the baseline time point can be stored in memory 82. The distal vector signal can be any signal sensed using the distal electrode 31 paired with any other available electrode. Figure 4 The atrial signal 109 sensed by the described sensing channel 81. The distal vector signal can be a broadband-filtered signal sensed by the morphological sensing channel 87 using the distal electrode 31 paired with the proximal electrode 28 or the housing 15. In some examples, two or more distal vector signals (each sensed using a sensing electrode vector including the distal electrode 31) can be obtained and analyzed to determine the corresponding baseline signal data at block 402.

[0138] At block 402, control circuitry 80 can acquire the proximal vector signal and determine one or more baseline features of the proximal vector signal at a baseline time point. Segments of the proximal vector signal at the baseline time point can be recorded in memory 82. The proximal vector signal can be a signal sensed by sensing circuitry 86 using a sensing electrode vector that is more proximal than the distal sensing electrode vector used to sense the distal vector signal. For example, the proximal vector signal can be any signal sensed using a sensing electrode vector that does not include the distal electrode 31. The proximal vector signal can be sensed using a proximal sensing electrode vector that includes the nearest electrode 28 paired with one of the defibrillation electrodes 15, pacing sensing electrode 30, or defibrillation electrodes 24 or 26. The proximal vector signal can be a ventricular signal 69 sensed by V sensing channel 83 or a ventricular sensing signal 122 determined to be a combination of atrial and ventricular signals (before or after low-pass filtering by filter 124), such as in combination. Figure 4 As described. In other examples, the proximal vector signal can be obtained by the morphological signal channel 87 as a broadband filtered signal sensed using the proximal electrode 28 paired with the housing 15, the electrode 30 paired with the housing 15, or the proximal electrode 28 paired with the electrode 30.

[0139] The baseline characteristics of the proximal vector signal can be similar to those determined from the distal vector signal. However, in some examples, the baseline characteristics of the proximal vector signal can differ from those of the distal vector signal. For example, the control circuit 80 can be based on the maximum peak amplitude received from sensing channel A 81 (e.g., see...). Figure 6 The representative P-wave amplitude can be determined from the distal vector signal, either by the peak amplitude 230 received from the V sensing channel 83 or by the maximum peak amplitude determined from the distal vector signal received by the control circuit 80. The control circuit 80 may also determine the representative P-wave amplitude based on the maximum peak amplitude received from the V sensing channel 83 (e.g., see [reference]). Figure 6 The peak amplitude 232 in the signal is used to determine the representative R-wave amplitude from the near-side vector signal, or the maximum peak amplitude determined from the near-side vector signal received by the control circuit 80.

[0140] In some examples, control circuitry 80 may combine distal and proximal vector signals at block 402 for storing baseline features and / or baseline signal segments. For example, distal vector signals may be sensed using distal electrode 31 in conjunction with proximal ring electrode 28. Proximal vector signals may be sensed using proximal ring electrode 28 in conjunction with housing 15. Distal and proximal vector signals may be combined, for example, by determining a sum or difference signal through addition or subtraction of the distal and proximal vector signals. For example, in some examples, the combined vector signal may be an atrial sensing signal 120 (before or after low-pass filtering by filter 111), determined by sensing circuitry 86 as a combination of atrial signal 109 and ventricular signal 69.

[0141] In some examples, P-wave signal segments can be stored from distal vector signals, proximal vector signals, and / or combinations of distal and proximal vector signals. P-wave signal segments can be stored such that they extend a specified number of sample points earlier and later than a P-wave sensing threshold exceedance caused by an atrial sensing signal received by P-wave detector 106. A P-wave signal segment can encompass exactly one sensed P-wave. In other examples, a P-wave signal segment can include multiple sensed P-waves based on timing of a P-wave sensing threshold exceedance detected by sensing channel A 81.

[0142] Additionally or alternatively, R-wave signal segments can be stored from distal vector signals, proximal vector signals, and / or combinations of distal and proximal vector signals. For example, R-wave signal segments can be stored such that they extend a specified number of sample points earlier and later than an R-wave sensing threshold exceedance caused by a ventricular sensing signal received by R-wave detector 66a. The R-wave signal segment can cover exactly one sensed R-wave. In other examples, the R-wave signal segment can include multiple sensed R-waves based on the timing of an R-wave sensing threshold exceedance detected by one of the V sensing channels 83 or 85.

[0143] In other examples, control circuit 80 acquires a cardiac signal segment including a T wave. The cardiac signal segment may include a P wave, a QRS waveform, and / or a T wave, enabling analysis of changes in the amplitude, shape, peak polarity, or other characteristics of atrial depolarization waveforms, ventricular depolarization waveforms, and / or ventricular repolarization waveforms.

[0144] After acquiring and storing the baseline signal data at block 402, control circuit 80 can wait at block 406 for the scheduled or triggered time for lead migration checking. When control circuit 80 determines at block 406 that it is time to perform lead migration checking, for example, according to the above... Figure 6In any of the examples described, control circuitry 80 can determine, at block 408, a distal vector signal feature similar to the distal vector signal feature previously determined at the baseline time point. At block 410, control circuitry 80 can determine a proximal vector signal feature previously determined from the proximal vector signal at the baseline time point.

[0145] At block 412, control circuit 80 can determine a signal difference for detecting changes in the distal vector signal and / or changes in the difference between the distal and proximal vector signals since the baseline time point. Control circuit 80 can determine the difference between the distal vector signal characteristics determined at the baseline time point and the distal vector signal characteristics determined at the current lead migration inspection time point, as described above. Figure 6 Broadly speaking, control circuit 80 can determine the difference between the near-side vector signal characteristics determined at the baseline time point and the near-side vector signal characteristics determined at the current lead migration inspection time point. Control circuit 80 can also determine the difference between the combined signal determined from the far-side vector signal and the near-side vector signal determined at the baseline time point and the combined signal determined at the current lead migration inspection time point.

[0146] At block 414, control circuitry 80 may apply lead migration detection criteria to the signal difference determined at block 412. Lead migration detection criteria may include one or more thresholds or ranges applied to corresponding signal characteristics or signal characteristic differences to detect evidence of migration at the distal end 29 of lead 16. In some examples, control circuitry 80 determines the change in the difference between the characteristics of the distal vector signal and the characteristics of the proximal vector signal from a baseline time point to the current time point. If the change in the difference between the distal vector signal characteristics and the proximal vector signal characteristics is greater than the threshold change, lead migration may be detected by control circuitry 80 at block 414. For example, control circuitry 80 may determine the maximum peak amplitude of the distal vector signal at the baseline and at the lead migration check time point (e.g., Figure 6 The peak amplitude shown is 230) and the maximum peak amplitude of the near-side vector signal (e.g., Figure 6 The ratio or difference between the peak amplitudes 230 and 232 shown. The control circuit 80 can compare the baseline ratio or baseline difference with a similar ratio or difference determined at the lead migration inspection time point. If the ratio or difference between the peak amplitudes 230 and 232 has changed the threshold percentage, the control circuit 80 can detect suspected lead migration.

[0147] In some examples, the distal vector signal and the proximal vector signal can be combined (e.g., in a difference signal) and compared with a baseline combined signal to determine the change in the difference between the distal and proximal vector signals relative to the baseline. For example, baseline features can be determined from the difference signal determined by subtracting time-aligned sample points from the distal and proximal vector signals. At the lead migration check time point, features can be determined from the difference signal determined by subtracting time-aligned sample points from the distal and proximal vector signals. The difference between the baseline features and the features at the lead migration check time point can be compared with a lead migration detection threshold. In some examples, the baseline features of the atrial sensing signal can be compared with similar features determined from the atrial sensing signal at lead migration check. The atrial sensing signal can be determined by sensing circuit 86 as a difference signal between the atrial and ventricular signals. Lead migration can be detected if the difference between the baseline features of the atrial sensing signal and the new features of the atrial sensing signal at lead migration check meets a threshold.

[0148] In some examples, the lead migration detection criteria applied at block 414 may require that the change in the far-side vector signal at the current time point relative to the baseline time point is greater than a threshold change. Control circuitry 80 may detect lead migration at block 414 when the currently determined feature of the far-side vector signal is greater than the threshold change relative to the baseline feature value of the far-side vector signal and the change in the difference between the far-side vector signal feature and the near-side vector signal feature is greater than the threshold change.

[0149] Alternatively or additionally, the lead migration detection criterion applied at block 414 may require that the change in the proximal vector signal at the current time point relative to the baseline time point be less than a threshold change. Control circuitry 80 may detect lead migration at block 414 when the currently determined characteristic of the proximal vector signal is less than the threshold change relative to the baseline characteristic value of the proximal vector signal, and the change in the difference between the distal vector signal characteristic and the proximal vector signal characteristic indicates a change greater than the threshold change.

[0150] In some examples, lead migration detection criteria may include a desired threshold change in the distal vector signal relative to the baseline distal vector signal, a threshold change in the difference between the distal and proximal vector signals relative to the baseline difference, and a threshold change in the proximal vector signal relative to the baseline proximal vector signal. Changes in the distal or proximal vector signal may be changes in peak amplitude, maximum or minimum slope, peak polarity, signal width, signal area, electrical event signal waveform morphology (e.g., P-wave, R-wave, or T-wave), or other selected characteristics of the corresponding signal determined to indicate a possible change in the signal that may occur with lead migration.

[0151] The difference between the combined distal and proximal vector signals relative to the baseline can be determined as the amplitude difference, slope difference, morphology matching score, or correlation between the baseline and current morphologies of the combined proximal and distal vector signals. It is conceivable that various signal features or signal feature differences can be determined from the distal vector signal, the proximal vector signal, and / or the combined signal determined from the distal and proximal vector signals (e.g., difference signal, summation signal, etc.) to detect a threshold change relative to the baseline signal that indicates a change in cardiac electrical signal due to lead migration. The threshold change or range can be expressed as a percentage of the baseline value, and as an example, could be... + 10% + 20% + 30% + 40% or + 50%.

[0152] If the lead migration detection criterion is not met at block 414, control circuit 80 can return to block 406 to wait for the next scheduled or triggered lead migration check. When the lead migration detection criterion is met at block 414, control circuit 80 can execute the lead migration detection response at block 416. At block 416, the above-described... Figure 6 Any example lead migration detection response described in the example lead migration detection response.

[0153] Figures 8A to 8C This is a diagram illustrating the possible changes in the distal and proximal vector signals due to lead migration. Figure 8A The diagram 500 shows the lead 16 of the heart 8 located at the baseline position and coupled to the ICD 14. Figure 8A The diagram includes a distal vector signal 510 and a proximal vector signal 520, which can be sensed by the sensing circuit 86 and analyzed by the control circuit of the ICD 14 to establish baseline time point features stored in the memory 82.

[0154] The distal vector signal 510 can be sensed using a distal sensing electrode vector 504 comprising the distal electrode 31 combined with the proximal electrode 28. The proximal vector signal 520 can be sensed using a proximal sensing electrode vector 506 comprising the proximal electrode 28 and the ICD housing 15. Each of the distal sensing electrode vector 504 and the proximal sensing electrode vector 506 is angularly positioned relative to the cardiac axis 502 at a baseline time point. The distal sensing electrode vector 504 is shown at an angle 521 relative to the cardiac axis 502. The proximal sensing electrode vector 506 is shown at an angle 525 relative to the cardiac axis 502. As the free distal end 29 of the lead 16 migrates, the angle of one or both of the distal sensing electrode vector 504 and the proximal sensing electrode vector 506 relative to the cardiac axis 502 can change, thereby causing changes in the corresponding signals 510 and 520, such as changes in peak amplitude and / or peak polarity or other morphological changes.

[0155] In Figure 500, the QRS waveforms of each of the distal vector signal 510 and the proximal vector signal 520 are shown. In the examples described below, for illustrative purposes, the characteristics of the QRS waveforms are described as being determined as baseline characteristics. However, it should be understood that one or more characteristics of the P-wave, QRS waveform, and / or T-wave of the distal vector signal 510 and / or the proximal vector signal 520 can be determined to establish baseline characteristics and to compare the baseline characteristics with lead migration inspection time-point characteristics to detect lead migration.

[0156] One or more features of the distal vector signal 510, one or more features of the proximal vector signal 520, and / or one or more quantitative relationships between the features of the distal vector signal 510 and the features of the proximal vector signal 520 can be determined by the control circuit 80 and stored in the memory 82 as baseline features. As described above, the baseline features can be determined as statistically representative values ​​derived from signal feature values ​​sampled during a data acquisition period (e.g., one hour, one day, one week, etc.) and stored in a histogram allocated in the memory 82.

[0157] In an exemplary example, the maximum positive peak amplitude 512 and the maximum (in absolute value) negative peak amplitude 514 of the distal vector signal 510 can be determined. The ratio, difference, and other quantitative relationship between the maximum positive peak amplitude 512 and the maximum negative peak amplitude 514 can be determined and stored in memory 82. The maximum positive peak amplitude 522 and the maximum (in absolute value) negative peak amplitude 524 of the proximal vector signal 520 can be determined. The ratio, difference, and other quantitative relationship between the maximum positive peak amplitude 522 and the maximum negative peak amplitude 524 can be determined by control circuitry 80 and stored in memory 82. In some examples, the ratio, difference, or other quantitative relationship between the maximum positive peak amplitude 512 of the distal vector signal 510 and the maximum positive peak amplitude 522 of the proximal vector signal 520 can be determined and stored in memory 82 as a baseline feature. The ratio, difference, or other quantitative relationship between the maximum negative peak amplitude 514 of the distal vector signal 510 and the maximum negative peak amplitude 524 of the proximal vector signal 520 can be determined and stored in memory 82 as a baseline feature.

[0158] It should be recognized that, in various examples, many characteristics of the distal vector signal and / or proximal vector signal can be determined to characterize the baseline signal. Furthermore, templates for the distal vector signal 510 and / or proximal vector signal 520 can be established at the baseline time point and stored in memory 82 for comparison with the corresponding signal waveforms obtained at the lead migration check time point.

[0159] Figure 8B This is illustration 550 of the lead 16 when the free distal end 29 has migrated to the patient's right side as indicated by directional arrow 551. In this illustrative example, with... Figure 8A Compared to the baseline position of the distal electrode vector 504 shown, the distal electrode vector 504 is shifted to be more aligned with the cardiac axis 502. The angle 541 between the distal sensing electrode vector 504 and the cardiac axis 502 is smaller than the baseline angle 521. The control circuit 80 can perform lead migration checks, including sensing the distal vector signal 560 via the distal sensing electrode vector 504 between the distal electrode 31 and the proximal electrode 28. In other examples, the distal vector signal can be sensed using an electrode typically carried along the distal portion of the lead 16, and in some examples, this electrode can be positioned relatively closer to the distal end 29 than the proximal end of the lead 16, without necessarily using the distal electrode 31 to sense the distal vector signal. Characteristics of the distal vector signal 560 (e.g., the maximum positive peak amplitude 562, the maximum negative peak amplitude 564, and the quantitative relationship between the maximum peak amplitude 562 and the maximum negative peak amplitude 564) can be determined by the control circuit 80 for comparison with corresponding baseline characteristic values.

[0160] Due to the change in the angle of the distal sensing electrode vector 504 relative to the cardiac axis 502, a change in the distal vector signal 560 compared to the baseline distal vector signal 510 may occur. These changes can be detected based on a comparative analysis (in Figure 8) of the characteristics of the distal vector signal 560 sensed during lead migration examination and the characteristics of the baseline distal vector signal 510. For example, the maximum negative peak amplitude 564 may decrease (in absolute value) compared to the baseline negative peak amplitude 514. The maximum positive peak amplitude 562 may increase compared to the baseline positive peak amplitude 512. For example, a change in the relative values ​​of the positive and negative peak amplitudes may occur when lead migration makes the distal sensing electrode vector 504 more aligned with the cardiac axis 502 (e.g., a smaller angle 541 compared to the baseline angle 521). The control circuit 80 can detect lead migration based at least on the change in the maximum negative peak amplitude and / or the change in the quantitative relationship between the maximum positive peak amplitude 512 and the maximum negative peak amplitude 514 compared with the baseline quantitative relationship between the maximum positive peak amplitude 562 and the maximum negative peak amplitude 564.

[0161] In this example, the proximal vector signal 540 can remain substantially the same as the baseline proximal vector signal 520 because the proximal sensing electrode vector 506 remains relatively constant, for example, relative to the cardiac axis 502 and the heart 8. The peak positive amplitude 542 and the peak negative amplitude 544 can be approximately equal to the baseline peak positive amplitude 522 and the peak negative amplitude 524, respectively (or within a threshold range of the baseline peak positive amplitude and the peak negative amplitude). In some examples, the control circuit 80 detects the migration of the distal end 29 of the lead based on the change in the distal vector signal 560 relative to the baseline distal vector signal 510. For example, the control circuit 80 can detect lead migration based at least on a decrease in the (absolute value) maximum negative peak amplitude 514 and / or an increase in the maximum positive peak amplitude 562 relative to the baseline signal 510. Although Figure 8B The illustration shows a decrease in the maximum negative peak amplitude 564 and an increase in the maximum positive peak amplitude 562. However, it should be understood that other changes in the distal vector signal 560 may occur when the distal lead end 29 migrates to the patient's right side, depending on the relative position of the distal sensing electrode vector 504 with respect to the heart 8 and the cardiac axis 502. In some examples, the control circuit 80 can detect lead migration when a threshold change in at least one feature of the distal vector signal 560 relative to the baseline distal vector signal 510 is detected, and the proximal vector signal 540 remains relatively unchanged compared to the baseline proximal vector signal 520.

[0162] Figure 8CThis is illustration 570 of lead 16 when the free distal end 29 has migrated to the patient's left side as indicated by directional arrow 571. In this example, the proximal vector signal 590 can remain substantially the same as the baseline proximal vector signal 520 because the position of the proximal sensing electrode vector 506 remains relatively constant, for example, relative to the cardiac axis 502 and the heart 8. The maximum positive peak amplitude 592 and the maximum negative peak amplitude 594 can remain relatively constant compared to the corresponding baseline maximum positive peak amplitude 522 and baseline maximum negative peak amplitude 524. In some examples, control circuitry 80 detects migration of the distal end 29 of the lead based on the change in the distal vector signal 580 relative to the baseline distal vector signal 510.

[0163] For example, control circuit 80 can detect lead migration based at least on the increase (absolute value) of the maximum negative peak amplitude 584. Additionally or alternatively, control circuit 80 can detect lead migration based on the decrease of the maximum peak amplitude 582 relative to the baseline maximum peak amplitude 512. An increase in the maximum negative peak amplitude 584 and a decrease in the maximum positive peak amplitude 582 may occur when the distal sensing electrode vector 504 shifts further away from alignment with the cardiac axis 502. In this case, the angle 591 between the distal sensing electrode vector 504 and the cardiac axis 502 has increased relative to the baseline angle 521. Although Figure 8C The illustration shows an increase in the maximum negative peak amplitude 584 and a decrease in the maximum positive peak amplitude 582. However, it should be understood that other changes in the distal vector signal 580 may occur when the distal lead tip 29 migrates to the patient's left side, depending on the relative position of the distal sensing electrode vector 504 with respect to the heart 8 and the cardiac axis 502. In some examples, the control circuit 80 may detect lead migration when a threshold change in at least one feature of the distal vector signal 580 relative to the baseline distal vector signal 510 is detected, and the proximal vector signal 590 remains relatively unchanged compared to the baseline proximal vector signal 520.

[0164] Figure 9 This is a diagram 600 of the lead 16 coupled to the ICD 14, illustrating the distal end 29 in the downward or tail-side direction, as indicated by the direction arrow 601, for example, relative to... Figure 8A The baseline position shift is shown. In this example, the proximal vector signal 620 can be relative to the baseline proximal vector signal 520 (see...). Figure 8A Change, because of Figure 8AThe angle 625 between the proximal sensing electrode vector 606 and the heart axis 602, as shown in the alignment of the baseline proximal sensing electrode vector 506 with respect to the heart axis 602 and the heart 8, changes (increases in this case) due to lead migration. In some examples, the control circuit 80 detects the migration of the distal end 29 of the lead based on the change in the proximal vector signal 620 relative to the baseline proximal vector signal 520. For example, the control circuit 80 may detect lead migration based at least on the increase (absolute value) of the maximum negative peak amplitude 624 compared to the maximum negative peak amplitude 524 of the baseline proximal vector signal 520. Additionally or alternatively, the control circuit 80 may detect lead migration based at least on the decrease in the maximum peak amplitude 622 of the proximal vector signal 620 compared to the baseline proximal vector signal 520. Although relative to Figure 8A The baseline proximal vector signal 520 in Figure 9 The illustration shows a decrease in the maximum positive peak amplitude 622 and an increase in the maximum negative peak amplitude 624 of the proximal vector signal 620. However, it should be understood that other changes in the proximal vector signal 620 may occur when the distal lead end 29 migrates in the caudal direction 601, depending on the relative position of the proximal sensing electrode vector 606 with respect to the heart 8 and the cardiac axis 602.

[0165] In this example, the QRS waveform of the far-side vector signal 610 can remain relatively unchanged compared to the baseline far-side vector signal 510 because it is relative to the baseline angle 521 (e.g., ...). Figure 8A Compared to (shown), the angle of the distal sensing electrode vector 604 relative to the cardiac axis 602 can remain relatively constant. However, due to the change in the position of the distal electrode 31 and the proximal electrode 28, the peak amplitude of the P wave (not shown) can decrease, the polarity can change, and / or the positive peak amplitude 612 and / or the negative peak amplitude 614 of the QRS can change relative to the baseline. Figures 8A to 9 The illustrations are intended to illustrate some changes that may occur in the distal and proximal vector signals due to migration of the distal end 29 of lead 16, and are not intended to be limiting. These examples are intended to illustrate how various combinations of characteristics of the distal and proximal vector signals determined at the baseline time point and a later lead migration check time point can be used to detect lead migration.

[0166] Figures 8A to 9This is described in the context of electrophysiological signals being sensed as cardiac electrical signals and electrical event signal characteristics being identified as cardiac event signal characteristics (e.g., peak amplitude and / or polarity of the P wave, QRS waveform, and / or T wave). It should be understood that the techniques disclosed herein for detecting lead migration may include identifying electrical event signal characteristics accompanying electrical activity detected from other types of sensed electrophysiological signals, such as electrical event signal characteristics determined from electrophysiological signals sensed from the brain, spinal cord, nerves, muscles, or other organs of the body. Such electrical event signals may correspond to electrical depolarization and / or repolarization of electrically excitable tissues, such as the nervous system, skeletal muscle, smooth muscle, or cardiac muscle.

[0167] This document also discloses the subject matter of the following embodiments: Example 1. A medical device system including a treatment delivery circuit configured to deliver electrical stimulation therapy. The medical device system includes a sensing circuit configured to receive one or more electrophysiological signals via a medical electrical lead having a distal end and carrying at least a distal electrode. The one or more electrophysiological signals include a distal vector signal received via a distal sensing electrode vector including the distal electrode. The medical device system includes control circuitry in communication with the sensing circuitry and the treatment delivery circuitry. The control circuitry is configured to control the treatment delivery circuitry to deliver the electrical stimulation therapy based on the one or more electrophysiological signals received by the sensing circuitry, and to detect migration of the medical electrical lead carrying the distal electrode based at least on the distal vector signal. The control circuitry may be configured to generate an output in response to detecting the migration of the medical electrical lead. The medical device system may include a memory configured to store data corresponding to the generated output.

[0168] Example 2. The medical device system according to Example 1, wherein the control circuit is further configured to determine a first feature of the distal vector signal at a first time point, determine a second feature of the distal vector signal at a second time point, and detect migration of the medical lead based at least on the difference between the first feature and the second feature.

[0169] Example 3. The medical device system according to Example 2, wherein the control circuit is further configured to determine the first feature and the second feature by determining at least one of peak amplitude, peak polarity, waveform morphology template, slope, signal width, or signal area.

[0170] Example 4. A medical device system according to any one of Examples 1 to 3, wherein the sensing circuit is further configured to receive a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode carried by the medical electrical lead. The proximal electrode is spaced proximally from the distal electrode on the medical electrical lead. The proximal sensing electrode vector does not include the distal electrode. The control circuit is further configured to: determine a difference between the distal vector signal and the proximal vector signal, and detect migration of the medical electrical lead based at least on the difference between the distal vector signal and the proximal vector signal and a difference between a first feature and a second feature of the distal vector signal.

[0171] Example 5. A medical device system according to any one of Examples 2 to 4, wherein the sensing circuit is further configured to receive a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode carried by the medical electrical lead. The proximal electrode is spaced proximally from the distal electrode on the medical electrical lead. The proximal sensing electrode vector does not include the distal electrode. The control circuit is further configured to: determine a third feature of the proximal vector signal at a first time point, determine a fourth feature of the proximal vector signal at a second time point, and detect migration of the medical electrical lead based at least on the difference between the first feature and the second feature satisfying a first threshold and the difference between the third feature and the fourth feature satisfying a second threshold.

[0172] Example 6. The medical device system according to Example 5, wherein the control circuit is further configured to determine that the difference between the third feature and the fourth feature satisfies the second threshold when the difference between the third feature and the fourth feature is less than the second threshold.

[0173] Example 7. A medical device system according to any one of Examples 1 to 6, wherein the sensing circuit is further configured to receive a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode carried by the medical electrical lead. The proximal electrode is spaced proximally from the distal electrode on the medical electrical lead. The proximal sensing electrode vector does not include the distal electrode. The control circuit is further configured to detect the migration of the medical electrical lead by at least based on the distal vector signal: determining a combined signal from the distal vector signal and the proximal vector signal at a first time point; determining the combined signal from the distal vector signal and the proximal vector signal at a second time point; detecting a change in the combined signal determined at the second time point relative to the combined signal determined at the first time point; and detecting the migration of the medical electrical lead carrying the distal electrode based on the detected change in the combined signal.

[0174] Example 8. A medical device system according to any one of Examples 1 to 7, wherein the control circuitry is further configured to generate the output by generating a lead migration detection notification. The medical device system further includes a telemetry circuitry configured to send the lead migration detection notification.

[0175] Example 9. A medical device system according to any one of Examples 1 to 8, wherein the control circuit is further configured to generate the output by adjusting sensing control parameters in response to detecting the migration of the medical lead.

[0176] Example 10. The medical device system according to Example 9, wherein the control circuit is further configured to adjust the sensing control parameters by adjusting at least one of the sensing electrode vector or the electrical event sensing threshold amplitude used by the sensing circuit to sense the one or more electrophysiological signals.

[0177] Example 11. A medical device system according to any one of Examples 1 to 10, wherein the control circuit is further configured to generate the output by adjusting arrhythmia detection control parameters in response to detecting the migration of the medical electrical lead, and to detect arrhythmia based on the adjusted arrhythmia detection control parameters. The control circuit is further configured to control the treatment delivery circuit to deliver the electrical stimulation therapy in response to detecting the arrhythmia.

[0178] Example 12. The medical device system according to Example 11, wherein the control circuit is further configured to adjust the arrhythmia detection control parameters by at least one of the following operations: adjusting a first threshold number of tachyarrhythmia intervals required for detecting tachyarrhythmias; or adjusting a second threshold number of tachyarrhythmia intervals required to trigger morphological analysis of the one or more electrophysiological signals received by the sensing circuit.

[0179] Example 13. A medical device system according to any one of Examples 1 to 12, wherein the control circuit is further configured to generate the output by performing a pacing capture test in response to detecting the migration of the medical lead.

[0180] Example 14. A medical device system according to any one of Examples 1 to 13, wherein the control circuit is further configured to generate the output by adjusting the treatment control parameters used by the treatment delivery circuit to deliver the electrical stimulation treatment.

[0181] Example 15. The medical device system according to Example 14, wherein the control circuit is further configured to adjust the treatment control parameters by adjusting at least one of the treatment delivery electrode vector or the treatment delivery pulse output.

[0182] Example 16. A medical device system according to any one of Examples 1 to 15, wherein the control circuit is further configured to generate the output by disabling the electrical stimulation therapy in response to detecting the migration of the medical electrical lead.

[0183] Example 17. A medical device system according to any one of Examples 1 to 16, wherein the sensing circuit is further configured to sense the one or more electrophysiological signals by sensing atrial and ventricular signals, sensing a P wave from the atrial signal, and sensing an R wave from the ventricular signal. The control circuit is further configured to detect, based on at least one of the sensed atrial signal, sensed P wave, sensed ventricular signal, or sensed R wave, either oversensing or undersensing of a suspected cardiac event signal caused by the sensing circuit. The control circuit is configured to, in response to detecting either oversensing or undersensing of the suspected cardiac event signal, perform a lead migration check for detecting the migration of the medical electrical lead, based at least on the distal vector signal.

[0184] Example 18. A medical device system according to any one of Examples 1 to 17, wherein the treatment delivery circuit is configured to deliver the electrical stimulation treatment by delivering a high-voltage cardioversion / defibrillation shock. The control circuit is further configured to perform a lead migration check in response to the delivery of the high-voltage cardioversion / defibrillation shock by the treatment delivery circuit for detecting the migration of the medical electrical leads.

[0185] Example 19. A medical device system according to any one of Examples 1 to 18, wherein the control circuit is further configured to determine, at a first time point, a first quantitative relationship between a first positive peak amplitude and a first negative peak amplitude of the distal vector signal from the distal vector signal. The control circuit is further configured to determine, at a second time point later than the first time point, a second quantitative relationship between a second positive peak amplitude and a second negative peak amplitude of the distal vector signal from the distal vector signal. The control circuit is further configured to detect the migration of the medical lead by at least based on the first quantitative relationship and the second quantitative relationship, and to detect the migration of the medical lead by at least based on the distal vector signal.

[0186] Example 20. The medical device system according to Example 19, wherein the sensing circuit is further configured to receive a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode carried by the medical electrical lead. The proximal electrode is spaced proximally from the distal electrode on the medical electrical lead. The proximal sensing electrode vector does not include the distal electrode. The control circuit is further configured to determine a third quantitative relationship between a first positive peak amplitude and a first negative peak amplitude of the proximal vector signal at a first time point, to determine a fourth quantitative relationship between a second positive peak amplitude and a second negative peak amplitude of the proximal vector signal at a second time point, and to detect migration of the medical electrical lead based at least on the first quantitative relationship, the second quantitative relationship, the third quantitative relationship, and the fourth quantitative relationship.

[0187] Example 21. A medical device system according to any one of Examples 1 to 20, the medical device system further comprising at least one medical electrical lead. The medical electrical lead is an extracardiac lead. The control circuitry is further configured to detect migration of the medical electrical lead after it has been implanted in an extracardiac location.

[0188] Example 22. A medical device system according to any one of Examples 1 to 21, wherein the treatment delivery circuit is further configured to deliver the electrical stimulation therapy by delivering cardiac electrical stimulation therapy, and the sensing circuit is further configured to receive the one or more electrophysiological signals by sensing at least one cardiac electrical signal.

[0189] Example 23. A method comprising: sensing one or more electrophysiological signals, the one or more electrophysiological signals including a distal vector signal sensed via a distal sensing electrode vector, the distal sensing electrode vector including a distal electrode of a medical electrical lead. The method includes detecting migration of the medical electrical lead carrying the distal electrode based at least on the distal vector signal. The method may include generating an output in response to detecting the migration of the medical electrical lead; and storing data corresponding to the output in a medical device memory.

[0190] Example 24. The method according to Example 23, the method further comprising: determining a first feature of the distal vector signal at a first time point; determining a second feature of the distal vector signal at a second time point; and detecting the migration of the medical lead based at least on the difference between the first feature and the second feature.

[0191] Example 25. According to the method of Example 24, the method further includes: determining the first feature and the second feature by determining at least one of peak amplitude, peak polarity, waveform morphology template, slope, signal width, or signal area.

[0192] Example 26. The method according to any one of Examples 23 to 25, further comprising: sensing a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode and excluding the distal electrode. The proximal electrode is spaced proximally from the distal electrode on the medical lead. The method further comprises: determining a difference between the distal vector signal and the proximal vector signal, and detecting migration of the medical lead based at least on the difference between the distal vector signal and the proximal vector signal and a difference between a first feature and a second feature of the distal vector signal.

[0193] Example 27. The method according to any one of Examples 24 to 26, further comprising: sensing a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode and excluding the distal electrode. The proximal electrode is spaced proximally from the distal electrode on the medical lead. The method further comprises: determining a third feature of the proximal vector signal at a first time point; determining a fourth feature of the proximal vector signal at a second time point; and detecting migration of the medical lead based at least on the difference between the first feature and the second feature satisfying a first threshold and the difference between the third feature and the fourth feature satisfying a second threshold.

[0194] Example 28. According to the method of Example 27, the method further includes: when the difference between the third feature and the fourth feature is less than the second threshold, determining that the difference between the third feature and the fourth feature satisfies the second threshold.

[0195] Example 29. The method according to any one of Examples 23 to 28, further comprising: sensing a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode and excluding the distal electrode. The proximal electrode is spaced proximally from the distal electrode on the medical lead. The method further comprises detecting the migration of the medical lead by at least based on the distal vector signal: determining a combined signal from the distal vector signal and the proximal vector signal at a first time point; determining the combined signal from the distal vector signal and the proximal vector signal at a second time point; detecting a change in the combined signal determined at the second time point relative to the combined signal determined at the first time point; and detecting migration of the medical lead carrying the distal electrode based on the detected change in the combined signal.

[0196] Example 30. The method according to any one of Examples 23 to 29, wherein generating the output includes: generating a lead migration detection notification and sending the lead migration detection notification.

[0197] Example 31. The method according to any one of Examples 22 to 29, wherein generating the output includes: adjusting sensing control parameters in response to detecting the migration of the medical electrical lead.

[0198] Example 32. According to the method of Example 31, adjusting the sensing control parameters includes: adjusting at least one of the sensing electrode vector or the electrical event sensing threshold amplitude used to sense the one or more electrophysiological signals.

[0199] Example 33. The method according to any one of Examples 23 to 32, the method further comprising: generating the output by adjusting arrhythmia detection control parameters in response to detecting the migration of the medical electrical lead; detecting arrhythmia based on the adjusted arrhythmia detection control parameters; and delivering electrical stimulation therapy in response to detecting the arrhythmia.

[0200] Example 34. The method according to Example 33, wherein adjusting the arrhythmia detection control parameters includes at least one of the following: adjusting a first threshold number of tachyarrhythmia intervals required for detecting tachyarrhythmias; or adjusting a second threshold number of tachyarrhythmia intervals required to trigger morphological analysis of the one or more electrophysiological signals received by the sensing circuit.

[0201] Example 35. The method according to any one of Examples 23 to 34, the method further comprising: generating the output by performing a pacing capture test in response to detecting the migration of the medical electrical lead.

[0202] Example 36. The method according to any one of Examples 23 to 35, the method further comprising: delivering electrical stimulation therapy, and wherein generating the output comprises: adjusting treatment control parameters for delivering the electrical stimulation therapy.

[0203] Example 37. The method according to Example 36, wherein adjusting the treatment control parameters includes: adjusting at least one of the treatment delivery electrode vector or the treatment delivery pulse output.

[0204] Example 38. The method according to any one of Examples 23 to 37, wherein generating the output includes disabling electrical stimulation therapy in response to detecting the migration of the medical electrical lead.

[0205] Example 39. The method according to any one of Examples 23 to 38, further comprising: sensing the one or more electrophysiological signals by sensing atrial and ventricular signals; sensing a P wave from the atrial signal; sensing an R wave from the ventricular signal; and detecting, based on at least one of the sensed atrial signal, sensed P wave, sensed ventricular signal, or sensed R wave, either suspected cardiac event signal oversensing or suspected cardiac event signal undersensing. The method further comprises: in response to detecting either suspected cardiac event signal oversensing or suspected cardiac event signal undersensing, performing a lead migration check for detecting the migration of the medical lead, at least based on the distal vector signal.

[0206] Example 40. The method according to any one of Examples 23 to 39, the method further comprising: delivering electrical stimulation therapy by delivering a high-voltage cardioversion / defibrillation shock, and performing a lead migration check in response to the delivery of the high-voltage cardioversion / defibrillation shock to detect the migration of the medical electrical lead.

[0207] Example 41. The method according to any one of Examples 23 to 40, further comprising: at a first time point, determining a first quantitative relationship between a first positive peak amplitude and a first negative peak amplitude of the distal vector signal from the distal vector signal; and at a second time point later than the first time point, determining a second quantitative relationship between a second positive peak amplitude and a second negative peak amplitude of the distal vector signal from the distal vector signal. The method may further comprise: detecting the migration of the medical lead by at least based on the first quantitative relationship and the second quantitative relationship, wherein the migration of the medical lead is detected at least based on the distal vector signal.

[0208] Example 42. The method according to Example 41, further comprising: sensing a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode and excluding the distal electrode, wherein the proximal electrode is spaced proximally from the distal electrode on the medical lead. The method further comprises: determining a third quantitative relationship between a first positive peak amplitude and a first negative peak amplitude of the proximal vector signal at a first time point; determining a fourth quantitative relationship between a second positive peak amplitude and a second negative peak amplitude of the proximal vector signal at a second time point; and detecting the lead migration based at least on the first quantitative relationship, the second quantitative relationship, the third quantitative relationship, and the fourth quantitative relationship, wherein the migration of the medical lead is detected at least based on the distal vector signal.

[0209] Example 43. The method according to any one of Examples 23 to 42, the method further comprising: detecting the migration of the medical electrical lead after implanting the medical electrical lead in an extracardiac location.

[0210] Example 44. The method according to any one of Examples 23 to 43, the method further comprising: controlling the delivery of electrical stimulation therapy based on the one or more electrophysiological signals.

[0211] Example 45. A non-transitory computer-readable medium storing an instruction set, which, when executed by control circuitry of a medical device, causes the medical device to sense a distal vector signal via a distal sensing electrode vector including a distal electrode of a medical electrical lead, and to sense a proximal vector signal via a proximal sensing electrode vector including a proximal electrode but excluding the distal electrode. The proximal electrode is located further away from the distal end of the medical electrical lead than the distal electrode. The instruction set also causes the medical device to detect migration of the medical electrical lead based on the distal and proximal vector signals, generate an output in response to detecting the migration of the medical electrical lead, and store data corresponding to the output in the medical device memory.

[0212] It should be understood that, depending on the example, certain actions or events in any of the methods described herein may be performed in a different order, and may be added, combined, or omitted entirely (e.g., not all described actions or events are necessary for practicing the method). Furthermore, in some examples, actions or events may be performed simultaneously, for example, through multithreading, interrupt handling, or multiple processors, rather than sequentially. In addition, for clarity, although some aspects of this disclosure are described as being performed by a single circuit or unit, it should be understood that the techniques of this disclosure may be performed by a combination of units or circuits associated with, for example, a medical device.

[0213] In one or more examples, the described functionality may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functionality may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. A computer-readable medium may include a computer-readable storage medium, which corresponds to a tangible medium such as a data storage medium (e.g., RAM, ROM, EEPROM, flash memory, or any other medium that can be used to store desired program code in the form of instructions or data structures and is accessible by a computer).

[0214] Instructions can be executed by one or more processors (such as one or more digital signal processors (DSPs)), general-purpose microprocessors, application-specific integrated circuits (ASICs), field-programmable logic arrays (FPLAs), or other equivalent integrated or discrete logic circuits. Therefore, as used herein, the term "processor" can refer to any of the foregoing structures or any other structure suitable for implementing the techniques described herein. Furthermore, these techniques can be fully implemented in one or more circuit or logic elements.

[0215] Therefore, a medical device has been presented in the foregoing description with reference to specific embodiments. It should be understood that the various aspects disclosed herein can be combined with combinations different from the specific combinations presented in the drawings. It should be understood that various modifications can be made to the reference examples without departing from the scope of this disclosure and the following claims.

Claims

1. A medical device system, the medical device system comprising: A treatment delivery circuit configured to deliver electrical stimulation therapy; A sensing circuit configured to receive one or more electrophysiological signals via a medical electrical lead having a distal end and carrying at least a distal electrode, the one or more electrophysiological signals including a distal vector signal received via a distal sensing electrode vector including the distal electrode. A control circuit, which communicates with the sensing circuit and the treatment delivery circuit, is configured to: Based on the one or more electrophysiological signals received by the sensing circuit, the treatment delivery circuit is controlled to deliver the electrical stimulation treatment; The migration of the medical electrical lead carrying the distal electrode is detected, at least based on the distal vector signal. as well as An output is generated in response to the detection of the migration of the medical electrical lead; and A memory configured to store data corresponding to the generated output.

2. The medical device system according to claim 1, wherein the control circuit is further configured to: Determine the first feature of the far-side vector signal at the first time point; Determine the second feature of the far-side vector signal at the second time point; and The migration of the medical electrical leads is detected based at least on the difference between the first feature and the second feature.

3. The medical device system of claim 2, wherein the control circuit is further configured to determine the first feature and the second feature by determining at least one of the following: Peak amplitude; Peak polarity; Waveform template; Slope; Signal width; or Signal area.

4. The medical device system according to any one of claims 2 to 3, wherein: The sensing circuit is further configured to receive a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode carried by the medical electrical lead, the proximal electrode being spaced proximally from the distal electrode on the medical electrical lead, and the proximal sensing electrode vector not including the distal electrode; and The control circuit is also configured to: Determine the difference between the distal vector signal and the proximal vector signal; and The migration of the medical lead is detected based at least on the difference between the distal vector signal and the proximal vector signal, and the difference between the first feature and the second feature of the distal vector signal.

5. The medical device system according to any one of claims 2 to 4, wherein: The sensing circuit is further configured to receive a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode carried by the medical electrical lead, the proximal electrode being spaced proximally from the distal electrode on the medical electrical lead, and the proximal sensing electrode vector not including the distal electrode; and The control circuit is also configured to: The third feature of the proximal vector signal is determined at the first time point; Determine the fourth feature of the proximal vector signal at the second time point; and The migration of the medical electrical lead is detected based at least on the difference between the first feature and the second feature satisfying a first threshold and the difference between the third feature and the fourth feature satisfying a second threshold.

6. The medical device system of claim 5, wherein the control circuit is further configured to: determine that the difference between the third feature and the fourth feature satisfies the second threshold when the difference between the third feature and the fourth feature is less than the second threshold.

7. The medical device system according to any one of claims 1 to 6, wherein: The sensing circuit is further configured to receive a proximal vector signal via a proximal sensing electrode vector, the proximal sensing electrode vector including a proximal electrode carried by the medical electrical lead, the proximal electrode being spaced proximally from the distal electrode on the medical electrical lead, and the proximal sensing electrode vector not including the distal electrode; and The control circuit is also configured to detect the migration of the medical lead by at least based on the distal vector signal: A combined signal is determined from the distal vector signal and the proximal vector signal at a first time point; The combined signal is determined from the distal vector signal and the proximal vector signal at a second time point; The change in the combined signal determined at the second time point relative to the combined signal determined at the first time point is detected; as well as The migration of the medical lead carrying the distal electrode is detected based on the changes in the detected combined signal.

8. The medical device system according to any one of claims 1 to 7, wherein the control circuitry is configured to generate the output by generating a lead migration detection notification; and The medical device system also includes a telemetry circuit configured to send the lead migration detection notification.

9. The medical device system according to any one of claims 1 to 8, wherein the control circuitry is further configured to generate the output by at least one of the following: The sensing control parameters are adjusted in response to the detection of the migration of the medical electrical lead; The arrhythmia detection control parameters are adjusted in response to the detection of the migration of the medical electrical lead. A capture test is performed in response to the detection of the migration of the medical electrical lead; or Adjust the treatment control parameters used by the treatment delivery circuit to deliver the electrical stimulation treatment.

10. The medical device system according to any one of claims 1 to 9, wherein the control circuitry is further configured to generate the output by disabling the electrical stimulation treatment in response to detecting the migration of the medical electrical lead.

11. The medical device system according to any one of claims 1 to 10, wherein: The sensing circuit is further configured to: The one or more electrophysiological signals are sensed by sensing atrial and ventricular signals; Sensing P waves from the atrial signals; and The R wave is sensed from the ventricular signal; and The control circuit is also configured to: The sensing circuit detects either oversensing or undersensing of a suspected cardiac event signal caused by the sensing circuit, based on at least one of a sensed atrial signal, sensed P wave, sensed ventricular signal, or sensed R wave. as well as In response to the detection of either oversensing or undersensing of the suspected cardiac event signal, a lead migration check for detecting the migration of the medical electrical lead is performed, at least based on the distal vector signal.

12. The medical device system according to any one of claims 1 to 11, wherein: The treatment delivery circuit is configured to deliver the electrical stimulation therapy by delivering a high-voltage cardioversion / defibrillation shock; and The control circuit is also configured to perform a lead migration check in response to the delivery of the high-voltage cardioversion / defibrillation shock by the treatment delivery circuit, for detecting the migration of the medical leads.

13. The medical device system according to any one of claims 1 to 12, wherein the control circuit is further configured to: At the first time point, a first quantitative relationship between the first positive peak amplitude and the first negative peak amplitude of the far-side vector signal is determined from the far-side vector signal; At a second time point later than the first time point, a second quantitative relationship between the second positive peak amplitude and the second negative peak amplitude of the distal vector signal is determined from the distal vector signal; and The migration of the medical electrical lead is detected by at least based on the first quantitative relationship and the second quantitative relationship, and the migration of the medical electrical lead is detected by at least based on the distal vector signal.

14. The medical device system according to any one of claims 1 to 13, the medical device system further comprising the medical electrical lead, wherein the medical electrical lead is an extracardiac lead, wherein the control circuitry is further configured to detect migration of the medical electrical lead after the medical electrical lead has been implanted in an extracardiac location.

15. The medical device system according to any one of claims 1 to 14, wherein: The treatment delivery circuit is also configured to deliver the electrical stimulation therapy by delivering cardiac electrical stimulation therapy; and The sensing circuit is also configured to receive the one or more electrophysiological signals by sensing at least one cardiac electrical signal.

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