Modifications to Cardiac Sensing and Therapy

Abstract

In some instances, a method for controlling the delivery of cardiac therapy and cardiac sensing by a medical device system that includes electrodes for delivering cardiac therapy may include storing in a memory of the medical device system: corresponding values for each of a plurality of cardiac therapy and / or sensing parameters, and corresponding modifications associated with each of a plurality of cardiac position states for at least one of the cardiac therapy and / or sensing parameters. The method may further include: determining a current cardiac position state of the plurality of cardiac position states of the patient; modifying at least one cardiac therapy and / or sensing parameter value according to the modification associated with the current cardiac position state; and controlling the delivery of the cardiac therapy and / or cardiac sensing according to the modified at least one cardiac therapy and / or sensing parameter value.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 716,798, filed on Aug. 9, 2018, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure generally relates to medical device systems and, more particularly, to cardiac sensing and therapy delivery via medical device systems. BACKGROUND

[0003] Some types of implantable medical device (IMD) systems, such as cardiac pacemaker or implantable cardioverter defibrillator systems, can be used to provide cardiac sensing and therapy to a patient via one or more electrodes. Some IMDs include an implantable housing that encloses a pulse generator and other electronic components, and the implantable housing can be configured to be implanted subcutaneously, such as in a patient's chest. The IMD can be connected to one or more implantable medical electrical leads that include one or more electrodes. The leads can be configured such that the electrodes can be implanted, for example, within the heart (e.g., transvenous leads) or external to the heart and vasculature (e.g., extravascular leads). Extravascular leads of such IMD systems can be configured such that, for example, electrodes positioned on a distal portion of the lead are implanted subcutaneously, sub-sternally, or in other extravascular locations. SUMMARY

[0004] In some instances, the present disclosure relates to techniques for controlling the delivery of cardiac therapies (e.g., anti-tachyarrhythmia shock therapy and / or cardiac pacing) and cardiac sensing via a medical device such as an IMD. Some such techniques can include storing values for cardiac therapy and / or sensing parameters, and storing corresponding modifications of at least one of the parameters associated with each of a plurality of cardiac position states. A cardiac position state can be a state of a patient that may correspond to different positions of the patient's heart relative to other anatomical structures and / or electrodes used by the medical device system for cardiac sensing and / or therapy. The cardiac position state can change based on one or more factors, such as a patient's posture or respiratory state. Thus, the cardiac position state can be defined by one or both of a posture or a respiratory state.

[0005] Such techniques can further include: determining a current cardiac position state of a patient's heart; modifying a cardiac therapy or a sensed parameter value based on a modification associated with the patient's current cardiac position state; and controlling a medical device to deliver a cardiac therapy and / or perform cardiac sensing based on the modified cardiac therapy parameter. Example parameters include cardiac pacing magnitude values (e.g., pulse amplitude or width), anti-tachyarrhythmia shock magnitude values (e.g., pulse amplitude, pulse width, and / or shock energy), or electrocardiogram sensing parameters, such as threshold amplitudes for detecting R waves, P waves, or other features of an electrocardiogram. In some instances, the parameter is a tachyarrhythmia detection parameter, which can be an electrocardiogram sensing parameter for detecting tachyarrhythmia. In some instances, the parameter is an electrode vector, which is used to sense an electrocardiogram and / or deliver a cardiac therapy through a modified electrode vector.

[0006] For all patients, an IMD system using transvenous leads may not be the preferred IMD system. For example, some patients may not be ideal candidates for placement of transvenous leads, such as patients with difficult vascular access, children, and other young patients. In addition, over time, transvenous leads can fibrose within the heart, making lead revision and extraction procedures challenging. An extracorporeal IMD system can eliminate the need for implanting transvenous leads within the heart. Thus, an extracorporeal IMD system can preferably be used for patients for whom a transvenous IMD is not preferred.

[0007] In some extracorporeal IMD systems, one or more leads can be implanted subcutaneously, subxiphoid, or in other extracorporeal locations. For example, an extracorporeal lead can be at least partially implanted in the subxiphoid space, such as at a target site between the thorax or sternum and the patient's heart. This lead positioning can enable the IMD connected to the lead to sense cardiac electrical signals through electrodes on the lead and deliver cardiac therapies, such as pacing pulses and / or anti-tachyarrhythmia shock therapies, to the patient's heart. For example, an extracorporeal lead can be implanted such that the electrodes on the lead are positioned relative to a target location of the patient's heart, such as relative to one or more chambers of the patient's heart. In this way, the energy delivered through the electrodes during the delivery of a cardiac therapy can be delivered to the target location.

[0008] However, in some instances, movement of a patient's heart relative to the electrodes of an extracorporeal lead can alter the efficacy and / or efficiency of a medical device in performing cardiac sensing and / or therapy. For example, in some patients, the heart may move within the patient's chest due to gravity when the patient changes position (e.g., from a supine or other flat position to an upright position), and / or when the patient is in certain respiratory states (e.g., inhaling, taking a deep breath, and / or breathing rapidly). For example, when a patient transitions from lying down to a standing position and / or when the patient inhales, the patient's heart may move caudally. In younger patients, the heart may rotate during standing and / or inhalation. In any such instance, movement of the heart relative to the electrodes of the IMD can affect one or more of the IMD's cardiac sensing and / or cardiac therapy delivery functions. For example, as the heart moves, the amplitude and / or morphology of the sensed cardiac electrical signals may change, which may result in reduced sensing specificity. During delivery of a pacing pulse, movement of the heart may cause the capture site to move around on the heart, such that the distance between the heart and the pacing electrodes on the lead changes. During delivery of an anti-tachyarrhythmia shock therapy, movement of the heart may cause the electrodes on the lead (e.g., the uppermost or most distal electrode) to contribute little current flowing through the heart during delivery of the shock therapy. In any such instance, one or more of the efficiency and / or efficacy of the cardiac therapy delivered by the IMD can be reduced at times when the heart is farther from the lead relative to times when the heart is closer to the lead.

[0009] Accordingly, it may be desirable to modify cardiac sensing and / or cardiac therapy delivery performed by the IMD to account for changes in the position of the patient's heart, such as position changes that may be associated with the patient's posture and / or respiration. For example, it may be desirable to modify sensing of cardiac electrical signals by the sensing electrodes of the IMD by adjusting sensing thresholds (e.g., amplitude thresholds), arrhythmia detection parameters, and / or blanking schemes based on the current position of the patient's heart. Such modification of the parameter values by which the IMD senses cardiac signals when the heart is in one or more particular positions can improve the specificity of arrhythmia detection performed by the IMD.

[0010] In some instances, it may be desirable to modify the delivery of cardiac pacing pulses and / or anti - arrhythmia shocks by an IMD, such as based on the magnitude and / or timing of the delivery of pacing pulses and / or anti - arrhythmia shocks relative to the current position of the patient's heart. Additionally or alternatively, it may be desirable to modify the electrode vectors used for cardiac sensing or cardiac therapy delivery by an IMD based on the current position of the patient's heart. In any such instance, modifying the delivery of cardiac sensing and / or cardiac therapy by an IMD to account for changes in the patient's heart position can enable the delivery of cardiac therapy by the IMD to be more efficient and / or effective when the heart is in certain positions. Accordingly, some of the techniques described herein can include modifying the delivery of cardiac sensing and / or cardiac therapy (e.g., cardiac pacing and / or anti - arrhythmia shock therapy) by a medical device system.

[0011] In one example, the present disclosure relates to a method of storing, in a memory of a medical device system, a respective value for each of a plurality of parameters for at least one of anti - arrhythmia shock therapy or cardiac sensing, and a respective modification associated with each of a plurality of heart position states for at least one of the plurality of parameters; and, by a processing circuitry of the medical device system, determining a current heart position state of the plurality of heart position states of the patient; modifying at least the parameter value according to the modification associated with the current heart position state; and controlling the delivery of the anti - arrhythmia shock therapy or at least one of the cardiac sensing according to the modified at least one parameter value.

[0012] In another example, the present disclosure relates to a medical device system including a plurality of electrodes; a memory configured to store a respective value for each of a plurality of parameters for at least one of anti - arrhythmia shock therapy or cardiac sensing, and a respective modification associated with each of a plurality of heart position states for at least one of the plurality of parameters; and a processing circuitry configured to: determine a current heart position state of the plurality of heart position states of the patient; modify at least one parameter value according to the modification associated with the current heart position state; and control the delivery of the anti - arrhythmia shock therapy or at least one of the cardiac sensing through the plurality of electrodes according to the modified at least one parameter value.

[0013] In another example, the present disclosure relates to a method for controlling electrocardiogram sensing or delivery of cardiac therapy by an implantable medical device system including a plurality of electrodes, the method comprising, by processing circuitry of the medical device system: determining a cardiac position state of a patient; modifying a vector including at least two of the plurality of electrodes based on the determined cardiac position state; and controlling the medical device system to sense an electrocardiogram or deliver cardiac therapy at least by the modified vector including the at least two of the plurality of electrodes.

[0014] In another example, the present disclosure relates to a medical device system for controlling electrocardiogram sensing or delivery of cardiac therapy, the system including a plurality of electrodes; and processing circuitry configured to: determine a cardiac position state of a patient; modify a vector including at least two of the plurality of electrodes based on the determined cardiac position state; and control the medical device system to sense an electrocardiogram or deliver cardiac therapy at least by the modified vector including the at least two of the plurality of electrodes.

[0015] This summary is intended to provide an overview of the subject matter described in the present disclosure. This summary is not intended to provide an exclusive or exhaustive interpretation of the methods and systems described in the following drawings and specification. Details of one or more aspects of the present disclosure are set forth in the following drawings and description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Details of one or more examples of the present disclosure are set forth in the following drawings and specification. Other features, objects, and advantages of the present disclosure will become apparent from the description, drawings, and claims.

[0017] Figure 1A is a conceptual diagram showing a front view of a patient with an example medical device system having a sub-sternal lead;

[0018] Figure 1B is a conceptual diagram showing a Figure 1A side view of a patient with an example medical device system;

[0019] Figure 1C is a conceptual diagram showing a Figure 1A transverse view of a patient with an example medical device system;

[0020] Figure 2 is a functional block diagram showing an example configuration of an Figure 1A example medical device system;

[0021] Figure 3is a functional block diagram showing an example system that includes an external device such as a server, and one or more computing devices coupled to an implantable medical device and the external device via a network; Figure 1A ; and an implantable medical device and one or more computing devices coupled to the external devices via a network

[0022] Figure 4 is a flowchart showing an example technique for determining corresponding modifications associated with each of a plurality of cardiac position states for at least one therapy parameter;

[0023] Figure 5 is a flowchart showing an example technique for modifying at least one therapy parameter value based on determining that a patient's cardiac position state has changed and in accordance with a modification associated with the patient's current cardiac position state; and

[0024] Figure 6 is a flowchart showing an example technique for modifying electrode vectors based on determining that a patient's cardiac position state has changed.

[0025] Figure 7 is an illustration showing four MRI scans (top) and corresponding models (bottom) that depict the position of a patient's heart within the patient's body.

[0026] Figure 8 is a plot of EV ICD cardiac signals for four patient postures.

[0027] Figure 9A and 9B are conceptual diagrams of MRI images of a patient's heart and an EV ICD in a supine position ( Figure 9A ) and an upright position ( Figure 9B ) during inspiration.

[0028] Figure 10 is an illustration showing the variation of DFT for various modeled patients with posture and respiration. DETAILED DESCRIPTION

[0029] In some examples, the present disclosure describes example techniques related to controlling sensing of cardiac electrical signals and / or delivery of cardiac therapies (e.g., cardiac pacing or anti-tachyarrhythmia shocks) by a medical device system based on a patient's current cardiac position state. In some examples, a processing circuitry of a medical device or other processing circuitry of a medical device system may determine a patient's current cardiac position state among a plurality of cardiac position states stored in a memory of the medical device system, the current cardiac position state being associated with a corresponding modification of at least one parameter among a plurality of cardiac therapies and / or sensing parameters. According to some example techniques described herein, the processing circuitry may also modify at least one cardiac therapy or sensing parameter value according to the modification associated with the current cardiac position state, and control delivery of the cardiac therapy according to the modified at least one cardiac therapy parameter value. In some examples, the processing circuitry may modify an electrode vector including at least two electrodes of a plurality of electrodes of the medical device system based on the current cardiac position state, and control the medical device system to sense at least an electrocardiogram or deliver a cardiac therapy through the modified electrode vector.

[0030] Each cardiac position state among the cardiac position states may be associated with one or more postures of a patient in a memory of the medical device system. For example, a cardiac position state where the heart is more caudal (e.g., relative to a baseline position) may be associated with a sitting, standing, or other upright posture. Thus, the processing circuitry may determine the patient's current cardiac position state by determining the patient's current posture. Additionally or alternatively, each cardiac position state among the cardiac position states may be associated with a respiratory state of the patient (such as at least one of an inspiration phase of the patient, a respiratory rate, or a respiratory depth). For example, a cardiac position state where the heart is more caudal relative to a baseline position may be associated with one or more of an inspiration phase, an increased respiratory rate, and / or an increased respiratory depth (e.g., relative to a baseline or other threshold respiratory value). In such examples, the processing circuitry may determine the patient's respiratory state based on signals received by one or more sensors of the medical device system, as discussed below with respect to Figure 1A-2 In some examples, the processing circuitry may further determine that the patient's respiratory state is at least one of an inspiration phase, a respiratory depth satisfying a respiratory depth threshold, or a respiratory rate satisfying a respiratory rate threshold.

[0031] In examples where the processing circuitry determines the current cardiac position state based on both posture and respiratory state, the determined posture and the determined respiratory state together may be associated with a different cardiac position state compared to separate cases. For example, when the patient is in an upright posture and taking a deep breath, the processing circuitry may determine that the patient's cardiac position state is different from when the patient is upright but not taking a deep breath or when the patient is lying down and taking a deep breath (e.g., because the heart may be more caudal).

[0032] To adapt cardiac therapies to a patient's cardiac position state, a processing circuitry can modify at least one cardiac therapy parameter value by modifying a tachyarrhythmia detection parameter based on a modification associated with the patient's current cardiac position state. For example, the tachyarrhythmia detection parameter can be a threshold heart rate (e.g., a certain number of heart beats per minute above a baseline heart rate), and if the threshold heart rhythm is met, a tachyarrhythmia can be indicated. However, a patient can have a different (e.g., higher) baseline heart rate during inspiration compared to expiration. If the tachyarrhythmia detection threshold is not adjusted to account for this difference in baseline heart rate during inspiration and expiration, false positive detections of tachyarrhythmia can occur during inspiration. Thus, when the patient's cardiac position state corresponds to inspiration, the processing circuitry can modify the tachyarrhythmia detection threshold by increasing the threshold, which can improve the accuracy of tachyarrhythmia detection during inspiration and reduce the likelihood of delivering unnecessary anti-tachyarrhythmia shocks, which can be uncomfortable for the patient or may unnecessarily consume the power of the medical device system. Other examples of tachyarrhythmia detection parameters that can be modified based on the cardiac position state include amplitude thresholds of an electrocardiogram for detecting features (such as R waves or P waves) of the electrocardiogram, or electrocardiogram morphology parameters such as templates for differentiating treatable tachyarrhythmias from other tachyarrhythmias (e.g., supraventricular tachyarrhythmias).

[0033] In some instances, the processing circuitry can modify at least one cardiac therapy parameter value by modifying an electrocardiogram sensing parameter, such as an amplitude threshold, in accordance with a modification associated with a patient's current cardiac position state. For example, when one or more sensing electrodes are approximately positioned over a target portion of the heart, such as a ventricle, a baseline electrocardiogram sensing amplitude threshold can be selected to enable sensing of a desired portion of the sensed electrocardiogram (e.g., the R wave). However, when the patient's heart position is caudal relative to a baseline position, such as when the patient is upright and / or inhaling, one or more other portions of the sensed electrocardiogram (e.g., the T wave) may be more prominent. In some such instances, over-sensing of the T wave can increase the likelihood of false positive detection of tachyarrhythmia. Thus, it can be beneficial to increase the sensing threshold amplitude associated with such other portions of the electrocardiogram to reduce the likelihood of false positive tachyarrhythmia detection. For example, when the patient's heart position is more caudal, the processing circuitry can modify the electrocardiogram sensing amplitude threshold by increasing it. In some instances, modifying the electrocardiogram sensing threshold improves the accuracy of tachyarrhythmia detection during inhalation, which can reduce the likelihood of delivering unnecessary anti-tachyarrhythmia shocks that may be uncomfortable for the patient or may unnecessarily consume power of the medical device system.

[0034] In some instances, the processing circuitry can modify at least one cardiac therapy parameter value by modifying an anti-tachyarrhythmia shock or pacing pulse magnitude (which can be pulse amplitude, width, or energy) in accordance with a modification associated with a patient's current cardiac position state. For example, when one or more defibrillation or pacing electrodes are approximately positioned over the heart, a baseline anti-tachyarrhythmia shock or pacing pulse magnitude can be selected to effectively treat tachyarrhythmia or maintain pacing capture. However, when the patient's heart position is caudal relative to a baseline position, such as when the patient is upright and / or inhaling, one or more of the defibrillation or pacing electrodes may no longer be approximately positioned over the heart. In some instances, this movement of the heart away from the electrodes can reduce the efficacy of anti-tachyarrhythmia shocks or can result in loss of pacing capture. In such instances, when the patient's cardiac position state corresponds to one or more postures or respiratory states associated with a more caudal (e.g., relative to baseline) heart position, the processing circuitry can modify the cardiac therapy parameter by increasing the anti-tachyarrhythmia shock magnitude or increasing the amplitude of one or more pacing pulses. By accounting for movement of the patient's heart relative to the defibrillation or pacing electrodes, the medical device system can deliver effective anti-tachyarrhythmia shock therapy or maintain pacing capture even when the heart moves away from the electrodes.

[0035] In some instances where a processing circuitry can modify at least one cardiac therapy parameter value based on a modification associated with a current cardiac position state of a patient, an anti-tachyarrhythmia shock therapy parameter can be a sensing vector and a shock vector, the sensing vector including at least two electrodes of a plurality of electrodes of a lead coupled to a medical device, and the shock vector including at least two electrodes of the plurality of electrodes. As discussed above, when the patient's heart position is caudal relative to a baseline position, one or more electrodes (e.g., sensing and / or defibrillation electrodes) positioned on a lead may no longer be approximately over the heart. In such instances, the processing circuitry can account for the heart position by removing one or more of the electrodes that are not approximately positioned over the heart from an electrode vector, because such electrodes may not be positioned to deliver sufficient energy to the heart or sense cardiac electrical signals when the heart is more caudal. For example, one or more electrodes removed from the sensing vector or the shock vector can be one or more electrodes positioned on a distal portion of the lead. In some instances, an anti-tachyarrhythmia shock delivered by the medical device using such a modified shock vector can improve the efficacy of anti-tachyarrhythmia shock therapy, such as by increasing the shock impedance and more efficiently directing and maintaining delivery of energy to the heart by the electrodes of the modified shock vector.

[0036] In some techniques where a processing circuitry can control a medical device system to sense an electrocardiogram or deliver cardiac therapy via a modified electrode vector, the processing circuitry can control the medical device system to deliver cardiac therapy by controlling the medical device system to deliver cardiac pacing via the modified vector. As discussed above, when the patient's heart is positioned caudal relative to a baseline position, one or more electrodes positioned on a lead (e.g., sensing and / or pacing electrodes positioned on a distal portion of the lead) may no longer be approximately positioned over a portion of the heart (such as a ventricle) to which it may be desirable to deliver pacing pulses. Alternatively, for example, when the heart is positioned caudal relative to a baseline position, one or more of the electrodes can be positioned over the atria of the heart. Pacing pulses delivered by one or more electrodes positioned over a non-target portion of the heart may not contribute to pacing efficacy and may reduce the energy efficiency of the medical device system. Thus, when the heart is positioned more caudally, it may be desirable to remove such electrodes from the pacing vector to improve pacing efficiency.

[0037] In any of the example techniques described herein, a modification to a cardiac therapy or a sensed parameter and / or an electrode vector can be selected by a clinician and programmed into the memory of a medical device system. Such modifications can be selected for an individual patient because the amount and / or direction by which a patient's heart can move with changes in posture and / or respiration can vary from patient to patient. Thus, the clinician can select a modification based on the amount and / or direction by which a particular patient's heart moves with changes in the patient's posture and / or respiration. For example, the heart of a patient with a smaller heart (e.g., a younger and / or female patient) may move less than the heart of a patient with a larger heart (e.g., an older and / or male patient). In some instances, the heart of a younger patient may rotate with changes in posture and / or respiration. Thus, the clinician can select a modification based on one or more of the patient's sex, age, or size (e.g., height and / or weight).

[0038] In some instances, the clinician can directly observe (e.g., via fluoroscopy) the amount and / or direction by which the patient's heart moves with changes in posture and / or respiration. In such instances, when the patient's heart moves with changes in the patient's posture and / or respiration, the medical device system can automatically or semi-automatically modify the values of one or more cardiac therapy parameters, cardiac sensed parameters, or electrode vectors. Thus, the techniques described herein can improve the efficacy and efficiency of cardiac therapy delivery by more accurately directing energy to a target portion of the heart and reducing energy delivery to non-target locations.

[0039] The medical device of the medical device system used in some of the example techniques in the example techniques can be an IMD configured for implantation in a patient (such as sub-sternally or subcutaneously) and can be configured to sense cardiac electrical signals and deliver cardiac therapy via at least one electrode of the IMD. In other instances, the medical device of the medical device system used in some of the example techniques in the example techniques can be an external medical device (e.g., not configured for implantation in a patient) that is configured to sense cardiac electrical signals and deliver anti-tachyarrhythmia shocks via at least one electrode of the medical device.

[0040] Figure 1A-1C is a conceptual diagram of a medical device system 10 implanted in patient 8. Figure 1A is a front view of a medical device system 10 implanted in patient 8. Figure 1B is a side view of a medical device system 10 implanted in patient 8. Figure 1C is a transverse view of a medical device system 10 implanted in patient 8.

[0041] In some examples, the medical device system 10 is an extracorporeal implantable cardioverter-defibrillator (EV-ICD) system implanted in a patient 8. However, the techniques described herein may be applicable to other implantable and / or external cardiac systems, including cardiac pacemaker systems, cardiac resynchronization therapy defibrillator (CRT-D) systems, cardioverter systems, wearable automatic external defibrillator (WAED) systems, or combinations thereof, as well as other stimulation and / or sensing systems, such as nerve stimulation systems. Additionally, the system 10 may not be limited to the treatment of human patients. In alternative examples, the system 10 may be implemented in non-human patients, such as primates, canines, equines, pigs, cows, sheep, felines, etc. These other animals may undergo clinical or research therapies that may benefit from the subject matter disclosed herein.

[0042] The IMD 12 is configured to be implanted in a patient, such as patient 8. In some instances, the IMD 12 is implanted subcutaneously or submuscularly on the upper left axilla of the patient 8 such that the IMD 12 may be positioned above the left thoracic cavity of the patient 8. In some other instances, the IMD 12 may be implanted at other subcutaneous locations on the patient 8, such as at a chest location or an abdominal location. The IMD 12 includes a housing 20 that may form an airtight seal protecting the IMD 12 components. In some instances, the housing 20 of the IMD 12 may be formed of a conductive material such as titanium or a combination of conductive and non-conductive materials that may serve as housing electrodes. The IMD 12 may also include a connector assembly (also referred to as a connector block or plug) that includes electrical feedthroughs through which electrical connections are made between the lead 22 and the electronic components contained within the housing. The housing 20 may house one or more of a processing circuitry, a memory, a transmitter, a receiver, a sensor, a sensing circuitry, a therapy circuitry, a power source, and other suitable components.

[0043] Generally, a medical device system (e.g., system 10) may include one or more medical devices, leads, external devices, or other components configured to implement the techniques described herein. In the illustrated example, the IMD 12 is connected to at least one implantable cardiac lead 22. In other examples, two leads may be used. In some instances, the IMD 12 may be configured to deliver high-energy anti-tachyarrhythmia (e.g., cardioversion or defibrillation) shocks to the patient's heart 18 upon detection of ventricular tachyarrhythmias (e.g., ventricular tachycardia (VT) or ventricular fibrillation (VF)). Cardioversion shocks are typically delivered in synchrony with the detected R wave when fibrillation detection criteria are met. Defibrillation shocks are typically delivered when fibrillation criteria are met and the R wave cannot be resolved from the signals sensed by the IMD 12.

[0044] The lead 22 includes an elongated lead body having a proximal end and a distal portion, the proximal end including a connector (not shown) configured to connect to the IMD 12, and the distal portion including electrodes 32A, 32B, 34A, and 34B. The lead 22 extends subcutaneously from the IMD 12 toward the center of the patient 8's torso above the thorax. At a location near the center of the torso, the lead 22 bends or turns and extends upward within the thoracic cavity below the sternum 24. Thus, the lead 22 can be at least partially implanted in the subxiphoid space, such as at a target site between the thorax or sternum 24 and the heart 18. In one such configuration, the proximal portion of the lead 22 can be configured to extend subcutaneously from the IMD 12 toward the sternum 24, and the distal portion of the lead 22 can be configured to extend upward below or beneath the sternum 24 in the anterior mediastinum 26( Figure 1C ). The lead 22 can include one or more bend segments as discussed herein to configure the lead 22 to extend in this manner naturally (e.g., in a self-biased manner) upon deployment.

[0045] For example, the lead 22 can extend upward within the thoracic cavity below or beneath the sternum 24 in the anterior mediastinum 26. The anterior mediastinum 26 can be considered to be bounded posteriorly by the pericardium 16, laterally by the pleura 28, and anteriorly by the sternum 24. In some instances, the anterior wall of the anterior mediastinum 26 can also be formed by the transversus thoracis muscle and one or more costal cartilages. The anterior mediastinum 26 contains a certain amount of loose connective tissue (such as areolar tissue), some lymphatic vessels, lymph nodes, subxiphoid muscle tissue (e.g., the transversus thoracis muscle), and small blood vessels or vascular branches. In one example, the distal portion of the lead 22 can be substantially implanted within the loose connective tissue and / or subxiphoid muscle tissue of the anterior mediastinum 26. In such examples, the distal portion of the lead 22 can be physically isolated from the pericardium 16 of the heart 18. A lead substantially implanted within the anterior mediastinum 26 will be referred to herein as a subxiphoid lead. Electrical stimulation provided by the lead 22 substantially implanted within the anterior mediastinum 26 (such as antiarrhythmic pacing, cardioversion, or defibrillation) can be referred to herein as subxiphoid electrical stimulation, subxiphoid pacing, impedance monitoring, subxiphoid cardioversion, or subxiphoid defibrillation.

[0046] The distal portion of lead 22 is described herein as being substantially implanted within the anterior mediastinum 26. Thus, some of the distal portion of lead 22 may extend outside of the anterior mediastinum 26 (e.g., the proximal end of the distal portion), but most of the distal portion may be located within the anterior mediastinum 26. In other embodiments, the distal portion of lead 22 may be implanted in other non-vascular extrapericardial locations within the thoracic cavity, including the perimeter around the pericardium 16 or other portions of the heart 18 and adjacent to but not attached to the pericardium or the other portions and not in the space, tissue, or other anatomical features above the sternum 24 or thoracic cage. As such, lead 22 may be implanted at any location within the "substernal space" defined by the lower surface between the sternum and / or thoracic cage and the body cavity, but not including the pericardium 16 or other portions of the heart 18. As is known to those skilled in the art, the substernal space may alternatively be referred to by the terms "retrosternal space" or "mediastinum" or "infrasternal", and includes the anterior mediastinum 26. The substernal space may also include the anatomical region described below as Larrey's space: Baudoin, Y.P. et al., entitled "The superior epigastric artery does not pass through Larrey's space (trigonum sternocostale)", Surg. Radiol. Anat. 25.3-4 (2003): 259-62. In other words, the distal portion of lead 22 may be implanted in the region around the outer surface of the heart 18, but not attached to the heart 18. For example, the distal portion of lead 22 may be physically isolated from the pericardium 16.

[0047] Lead 22 may include an insulated lead body having a proximal end and a distal portion, the proximal end including a connector 30 configured to connect to the IMD 12, and the distal portion including one or more electrodes. As Figure 1A shown, one or more electrodes of lead 22 may include electrodes 32A, 32B, 34A, and 34B, but in other instances, lead 22 may include more or fewer electrodes. Lead 22 also includes one or more conductors that form an electrical conduction path within the lead body and interconnect the electrical connector with the respective electrodes.

[0048] The electrodes 32A, 32B can be defibrillation electrodes (either alone or together, "one or more defibrillation electrodes 32"). Although the electrodes 32 may be referred to herein as "defibrillation electrodes 32", the electrodes 32 can be configured to deliver other types of anti - tachyarrhythmia shocks, such as cardioversion shocks. In some instances, the defibrillation electrodes 32A, 32B can be functionally different segments of a single defibrillation electrode 32 such that both defibrillation electrodes 32 are coupled to the same conductor or otherwise configured to provide the same electrical stimulation. Although the defibrillation electrodes 32 are depicted as coil electrodes in Figure 1A-1C for clarity, it should be understood that the defibrillation electrodes 32 can have other configurations in other instances, such as elongated coil electrodes. The defibrillation electrodes 32 can be positioned on the distal portion of the lead 22, where the distal portion of the lead 22 is a part of the lead 22 configured to extend along the sternum 24 for implantation.

[0049] The lead 22 can be implanted below the sternum 24 or at a target site along the sternum such that the therapy vector substantially straddles the ventricles of the heart 18. In some instances, the therapy vector (e.g., the shock vector for delivering an anti - tachyarrhythmia shock) can be between the defibrillation electrodes 32 and a can electrode formed on or by the IMD 12, as discussed further below. In one instance, the therapy vector can be considered as a line that extends from a point on the defibrillation electrode 32 (e.g., the center of one of the defibrillation electrodes 32) to a point on the can electrode of the IMD 12. Thus, it may be advantageous to increase the amount of the region in which the defibrillation electrodes 32 (and thus the distal portion of the lead 22) extend across the heart 18. Accordingly, the lead 22 can be configured to define a curved distal portion as depicted in Figure 1A . In some instances, in addition to the techniques for controlling the delivery of the cardiac therapies described herein, the curved distal portion of the lead 22 can also help improve the efficacy and / or efficiency of the IMD 12 for pacing, sensing, and / or defibrillating the heart 18.

[0050] The electrodes 34A, 34B can be pacing / sensing electrodes 34A, 34B (either alone or together, "one or more pacing / sensing electrodes 34") positioned on the distal portion of the lead 22. The electrodes 34 are referred to herein as pacing / sensing electrodes because they are typically configured for the delivery of pacing pulses and / or the sensing of cardiac electrical signals. In some cases, the electrodes 34 can provide only a pacing function, only a sensing function, or both a pacing function and a sensing function. In Figure 1A and Figure 1BIn the illustrated example, the pacing / sensing electrodes 34 are separated from each other by the defibrillation electrode 32B. However, in other examples, the pacing / sensing electrodes 34 can all be distal to the defibrillation electrode 32B, or all be proximal to the defibrillation electrode 32B. In examples where the lead 22 includes more or fewer electrodes 32, 34, such electrodes can be located at other positions on the lead 22. In some examples, the IMD 12 can include one or more electrodes 32, 34 on another lead (not shown). Other lead configurations can be used, such as various electrode arrangements. For example, one or more pacing / sensing electrodes 34 can be placed between two defibrillation electrodes 32, as described above. In one example, multiple pacing / sensing electrodes 34 can be placed between two defibrillation electrodes 32. For example, two defibrillation electrodes 32 can be adjacent (e.g., such that the two defibrillation electrodes 32 are not separated by any pacing / sensing electrodes 34 between the two defibrillation electrodes 32). Other arrangements can be used additionally or alternatively.

[0051] The lead 22 can define different sizes and shapes, such as sizes and shapes that can be suitable for different purposes (e.g., suitable for different patients or suitable for different therapies). As discussed above, in some examples, the distal portion of the lead 22 can have one or more curved segments. As Figure 1A shown in the example of, the distal portion of the lead 22 is a meandering shape that includes two "C" - shaped curves that together may resemble the Greek letter "epsilon". Each defibrillation electrode 32 is carried by one of the two corresponding C - shaped portions of the distal part of the lead body. The two C - shaped curves extend or bend away from the central axis of the lead body in the same direction. In some examples, the pacing / sensing electrodes 34 can be approximately aligned with the central axis of the straight proximal portion of the lead 22. In such examples, the mid - point of the defibrillation electrode 32 is laterally offset from the pacing / sensing electrode 34. Other examples of extracardiac leads that include one or more defibrillation electrodes and one or more pacing / sensing electrodes 34 carried by a curved, meandering, wavy, or zig - zag distal portion of the lead 22 can also be implemented using the techniques described herein. In some examples, the distal portion of the lead 22 can be straight (e.g., straight or nearly straight).

[0052] In some instances, the electrode arrangement on lead 22 can correspond to the geometry of lead 22. For example, the pacing / sensing electrode 34 can be positioned at opposite peaks of a curved lead shape, while the defibrillation electrode 32 can be positioned at opposite valleys of the curved lead shape. In other instances, the distal portion of lead 22 can include branches, offset portions extending away from the central axis, or other shapes that can provide appropriate monitoring information or therapy (e.g., where one or more of electrodes 32, 34 are disposed on a branch, shaft, or offset portion). Deploying lead 22 such that electrodes 32, 34 are thus at the peaks and valleys of these depicted serpentine shapes can enhance the efficacy of system 10 therein. For example, in addition to the techniques described herein for controlling the delivery of cardiac therapy, when lead 22 is deployed in a serpentine shape, electrodes 32, 34 can also obtain better sensing or therapy vectors.

[0053] Adjusting the orientation of the serpentine-shaped lead such that the pacing / sensing electrode 34 is closer to the heart 18 can provide better inductive sensing of cardiac signals and / or a lower pacing capture threshold compared to if the pacing / sensing electrode 34 were oriented farther from the heart 18. The serpentine or other shape of the distal portion of lead 22 can increase fixation to the patient 8, as the shape provides resistance to adjacent tissue when an axial force is applied. Another advantage of the shaped distal portion is that, relative to a lead having a straighter distal portion, the pacing / sensing electrode 34 can obtain a larger surface area over a shorter length of the heart 18.

[0054] In some instances, the elongate lead body of lead 22 can include one or more elongate electrical conductors (not shown) that extend within the lead body from a connector at the proximal lead end to electrodes 32, 34 positioned along the distal portion of lead 22. The one or more elongate electrical conductors included within the lead body of lead 22 can be coupled to corresponding ones of electrodes 32, 34. In one instance, each of electrodes 32, 34 is electrically coupled to a corresponding conductor within lead 22. The corresponding conductors can be electrically coupled through connections (including associated feedthroughs) in the connector assembly to circuitry in the IMD 12, such as a therapy module or a sensing module. The electrical conductors transmit therapy from the therapy module within the IMD 12 to one or more of electrodes 32, 34, and transmit sensed electrical signals from one or more of electrodes 32, 34 to the sensing module within the IMD 12.

[0055] In some instances, the diameter of the elongated lead body of lead 22 can be between 3 French (Fr) and 9 Fr, but lead bodies with diameters less than 3 Fr and greater than 9 Fr can also be utilized. In another instance, the distal portion and / or other portions of the lead body can have a flat, ribbon, or paddle shape. In such instances, the width of the flat portion of the flat, ribbon, or paddle shape can be between 1 mm and 3.5 mm. Other lead body designs can be used without departing from the scope of the present disclosure. The lead body of lead 22 can be formed of a non-conductive material including silicone, polyurethane, fluoropolymer, mixtures thereof, and other suitable materials, and shaped to form one or more lumens within which one or more conductors extend. However, the techniques are not limited to such configurations.

[0056] In some instances, the defibrillation electrode 32 can have a length greater than 5 centimeters (cm) and less than 10 cm, or a length between about 2 cm and about 16 cm. In other instances, in addition to the elongated coil electrode, the defibrillation electrode 32 can be a flat ribbon electrode, a paddle electrode, a braided or interlaced electrode, a mesh electrode, a segmented electrode, an oriented electrode, a patch electrode, or other types of electrodes.

[0057] The pacing / sensing electrode 34 can include an annular electrode, a short coil electrode, a hemispherical electrode, a segmented electrode, an oriented electrode, etc. In some instances, the pacing / sensing electrode 34 can have substantially the same outer diameter as the lead body. In one instance, the pacing / sensing electrode 34 can have a surface area between 1.6 - 55 mm 2 between. In some instances, the pacing / sensing electrode 34 can have relatively the same surface area or different surface areas. Depending on the configuration of lead 22, the pacing / sensing electrode 34 can be spaced apart by the length of the defibrillation electrode 32 plus a certain insulation length on each side of the defibrillation electrode 32 (e.g., approximately 2 - 16 cm). In other instances, such as when the pacing / sensing electrode 34 is between the segments of a segmented defibrillation electrode 32, the electrode spacing can be smaller, e.g., less than 2 cm or less than 1 cm. The exemplary dimensions provided above are exemplary in nature and should not be considered as limiting the instances described herein. In other instances, lead 22 can include a single pacing / sensing 34 or more than two pacing / sensing electrodes 34.

[0058] In some instances, the IMD 12 can include one or more case electrodes (not shown) positioned on the case 20 of the IMD 12. Such case electrodes can be integrally formed with the outer surface of the hermetically sealed case 20 of the IMD 12, or can be otherwise coupled to the case 20. In some instances, the case electrode can be defined by an uninsulated portion of the outward-facing portion of the case 20 of the IMD 12. In some instances, the case 20 can define one or more additional case electrodes, which can be defined by a corresponding division between an insulated portion and an uninsulated portion of the case 20. In still other instances, substantially all of the case 20 can be uninsulated such that substantially all of the case 20 defines a case electrode.

[0059] Generally, the system 10 can sense electrical signals, such as via one or more sensing vectors that include a combination of the pacing / sensing electrode 34 and / or the case electrodes of the IMD 12. In some instances, the IMD 12 can use a sensing vector to sense cardiac electrical signals, the sensing vector including one or both of the defibrillation electrodes 32 and / or one of the defibrillation electrodes 32 and one of the pacing / sensing electrodes 34 or a case electrode of the IMD 12. The sensed electrical endogenous signals can include electrical signals generated by the myocardium and indicative of depolarization and repolarization of the heart 18 at different times during the cardiac cycle. The IMD 12 can be configured to analyze the electrical signals sensed by one or more sensing vectors to detect tachyarrhythmias such as ventricular tachycardia (VT) or ventricular fibrillation (VF). In response to detecting a tachyarrhythmia, the IMD 12 can begin charging a storage element such as one or more capacitor banks, and when charged, deliver sub-xiphoid electrical stimulation therapy, e.g., ATP, cardioversion, or defibrillation shock, and / or post-shock pacing in response to detecting tachycardia (e.g., VT or VF). In some instances, in addition to ATP, cardioversion, or defibrillation shock and / or post-shock pacing, the IMD 12 can also generate and deliver bradycardia pacing.

[0060] The processing circuitry of the IMD 12 can sense patient parameters indicative of the current cardiac position state of the heart 18 based on signals sensed by one or more sensors of the system 10. It should be noted that although this processing circuitry can be included within the IMD 12 and / or within another device of the system 10 (e.g., the external device 38), for clarity, the processing circuitry is described herein as a component of the IMD 12. In some instances, the processing circuitry of the system 10 can determine the current posture of the patient 8 and / or the respiratory state of the patient 8. For example, the system 10 can include one or more accelerometers or gyroscopes (not shown). One or more accelerometers can include one or more triaxial accelerometers. In some instances, such accelerometers or gyroscopes can be components of the IMD 12 of the system 10. Signals generated by such sensors can indicate, for example, the current posture of the patient 8, such as an upright posture, a sitting posture, a supine or prone posture, or other postures. In some instances, when the patient 8 is in an upright posture, the heart 18 can be positioned up to about 6 cm more caudally relative to a baseline position compared to when the patient 8 is in a supine posture.

[0061] In some instances, the processing circuitry of the IMD 12 can determine the respiratory state of the patient 8 by determining one or more of the inspiratory period, respiratory depth, or respiratory rate of the patient 8. In some such instances, the processing circuitry of the IMD 12 can compare the respiratory depth and / or respiratory rate to one or more corresponding thresholds. If the respiratory depth and / or respiratory rate meet one or more corresponding thresholds, the processing circuitry can, for example, identify the respiratory depth as "deep" and / or the respiratory rate as "high". In some such instances, the processing circuitry of the IMD 12 can further identify the magnitude of such aspects of the respiratory state of the patient 8, such as identifying the respiratory depth as "moderate depth" or "very deep". Such magnitudes of the respiratory state can correspond to different position states of the heart 18. For example, during very deep breathing, the heart 18 can be positioned more caudally than during moderate depth breathing (e.g., up to about 2 - 4 cm more caudally).

[0062] In some instances, the processing circuitry of the IMD 12 can determine the respiratory state of the patient 8 based on the impedance between two or more electrodes (e.g., two or more of the pacing / sensing electrode 34 and / or the can electrode on the can 20). In other instances, the system 10 can include one or more other sensors configured to determine the respiratory state of the patient 8, such as a microphone configured to detect sounds associated with the patient 8's respiration, a magnetometer configured to measure dimensional changes of the patient 8's thoracic anatomy during respiration, or a pressure sensor configured to measure changes in pressure applied to the lead 22 associated with changes in the respiratory state. In some instances, an accelerometer can generate a signal that varies based on respiration, e.g., based on vibrations and / or movement associated with respiration. Regardless of the configuration of such sensors, the processing circuitry of the IMD 12 can determine the posture of the patient 8 and / or the respiratory state of the patient 8 based on signals obtained therefrom, and associate the posture and / or respiratory state of the patient 8 with the current cardiac position state of the heart 18 among a plurality of cardiac position states stored in the memory of the system 10, the current cardiac position state being associated with a corresponding modification of at least one parameter among a plurality of cardiac sensing, cardiac therapy, or vector parameters.

[0063] In some instances, the processing circuitry of the IMD 12 can then modify at least one cardiac therapy and / or sensing parameter value according to the modification associated with the current cardiac position state of the heart 18, and control the delivery of cardiac therapy. For example, according to the modified at least one cardiac therapy parameter value, the processing circuitry of the IMD 12 can control the delivery of an anti-tachyarrhythmia shock via the defibrillation electrode 32 (and the IMD can thus deliver an anti-tachyarrhythmia shock), and / or control cardiac pacing via the pacing / sensing electrode 34. In some other instances, the processing circuitry of the IMD 12 can modify an electrode vector based on the current cardiac position state of the heart 18, such as a cardiac therapy delivery vector including at least two of the defibrillation electrodes 32 or a sensing vector including at least two of the pacing / sensing electrodes 34. In such instances, the processing circuitry of the IMD 12 can control the IMD 12 to sense at least an electrocardiogram via the modified sensing vector or deliver cardiac therapy via the modified electrode vector.

[0064] In some instances, the processing circuitry of the IMD 12 can modify cardiac therapy and / or sensing parameter values by modifying tachyarrhythmia detection parameters based on a modification associated with the current cardiac position state of patient 8 in the memory of system 10. For example, the tachyarrhythmia detection parameter can be a threshold heart rate of patient 8 (e.g., a certain number of heartbeats per minute above a baseline heart rate). If met, the threshold heart rate can indicate that patient 8 is experiencing tachyarrhythmia. However, patient 8 may have a higher baseline heart rate during inspiration compared to expiration. Thus, when the cardiac position state of patient 8 corresponds to the inspiratory phase of respiration, the processing circuitry of the IMD 12 can modify the tachyarrhythmia detection threshold by increasing the tachyarrhythmia detection threshold heart rate. In some instances, using an increased tachyarrhythmia detection threshold heart rate during inspiration can improve the tachyarrhythmia detection accuracy of system 10, such as by reducing the likelihood of false positive tachyarrhythmia detections. In some instances, reducing the likelihood of false positive tachyarrhythmia detections can reduce the likelihood of delivering unnecessary anti-tachyarrhythmia shocks to patient 8, which can avoid unnecessary discomfort associated with patient 8 and / or avoid unnecessary consumption of the power source of system 10.

[0065] In some instances, the processing circuitry of the IMD 12 can modify cardiac therapy and / or sensed parameter values (by which the IMD 12 can deliver cardiac therapy) by modifying the electrogram sensing amplitude threshold based on a modification associated with the current cardiac position state of the patient 8 in the memory of the system 10. For example, when programming the IMD 12, a clinician can select a baseline electrogram sensing amplitude threshold that enables the IMD 12 to sense a target portion of the electrogram (e.g., an R wave) through the pacing / sensing electrode 34 for tachyarrhythmia detection when one or more of the pacing / sensing electrodes 34 are approximately positioned over a particular portion of the heart 18, such as the ventricle. However, when the heart 18 is caudal relative to the baseline position, such as when the patient 8 is in an upright position and / or inhaling, one or more other portions of the sensed electrogram (e.g., a T wave) may be more prominent. In some such instances, oversensing of the T wave or other non-target portions of the electrogram by the IMD 12 can increase the likelihood of false positive detection of tachyarrhythmia. Thus, the clinician can program the IMD 12 to increase the sensed threshold amplitude associated with such other portions of the electrogram to reduce the likelihood of false positive tachyarrhythmia detection. For example, when the current position of the heart 18 is caudal relative to the baseline position, the processing circuitry of the IMD 12 can modify the electrogram sensing amplitude threshold by increasing the electrogram sensing amplitude threshold of the IMD 12, which can enable the system 10 to better sense the target portion of the electrogram when the heart 18 is in such a position.

[0066] In some instances, the processing circuitry of the IMD 12 can modify cardiac therapy parameter values by modifying an anti-tachyarrhythmia shock magnitude or one or more pacing pulse amplitudes (by which the IMD 12 can deliver cardiac therapy) based on a modification associated with the current cardiac position state of the patient 8 in the memory of the system 10. For example, a clinician can select a baseline anti-tachyarrhythmia shock magnitude or a baseline pacing pulse amplitude (e.g., when programming the IMD 12) that can effectively treat tachyarrhythmias or provide pacing capture of the heart 18 when the defibrillation electrodes 32 or the pacing / sensing electrodes 34 are approximately positioned over the heart 18. However, when the heart 18 is caudal relative to the baseline position, such as when the patient 8 is upright and / or inhaling, one or more of the defibrillation electrodes 32 or the pacing / sensing electrodes 34 may no longer be approximately positioned over the heart 18. In such cases, during delivery of a cardiac pacing pulse by the IMD 12, the efficacy of the anti-tachyarrhythmia shock delivered by the IMD 12 may be reduced or pacing capture may not be maintained. Thus, in such instances, when the posture and / or respiratory state of the patient 8 corresponds to a lower cardiac position state, the processing circuitry of the IMD 12 can modify the cardiac therapy parameters by increasing the anti-tachyarrhythmia shock magnitude or increasing the amplitude of one or more pacing pulses. In some such instances, increasing the anti-tachyarrhythmia shock magnitude or increasing the amplitude of one or more pacing pulses can improve the efficacy of the anti-tachyarrhythmia shock therapy or pacing capture, which can result in improved clinical outcomes of cardiac therapy for the patient 8 compared to example cardiac therapy techniques that do not account for the patient's cardiac position.

[0067] In some instances, the processing circuitry of the IMD 12 can modify cardiac therapy parameter values by modifying at least one of a sensing vector that includes at least two of the pacing / sensing electrodes 34 or a shock vector that includes at least two of the defibrillation electrodes 32 in accordance with a modification associated with the current cardiac position state of patient 8 in the memory of system 10. As discussed above, when the heart 18 is caudal relative to the baseline position, one or more of the pacing / sensing electrodes 34 and / or defibrillation electrodes 32 may no longer be approximately positioned over the heart 18. In such instances, the processing circuitry of the IMD 12 can be configured to modify at least one electrode vector by removing one or more of the pacing / sensing electrodes 34 from the sensing vector or removing one or more of the defibrillation electrodes 32 from the shock vector. The electrode 34 or 32 removed from the sensing vector or shock vector can be one of the electrodes 32, 34 that is no longer positioned over the heart 18 when the heart 18 is caudal relative to the baseline position. For example, the processing circuitry of the IMD 12 can remove one or more electrodes positioned on the distal portion of the lead from the electrode vector, such as one or more of the uppermost or most distal electrodes of electrodes 32 or 34. In some instances, an anti-tachyarrhythmia shock delivered by the IMD 12 using this modified shock vector can enhance the efficacy of the anti-tachyarrhythmia shock therapy, such as by increasing the shock impedance. In some instances, even though the total energy delivered by the IMD 12 using the modified shock vector may be less than the total energy delivered by the corresponding unmodified shock vector, the increased shock impedance of the modified shock vector can more efficiently direct and sustain the energy delivery to the heart 18 through the remaining defibrillation electrodes of the defibrillation electrodes 32 in the modified shock vector.

[0068] In any such instance in which the processing circuitry of the IMD 12 can modify cardiac therapy parameter values in accordance with a modification associated with the current cardiac position state of patient 8 in the memory of system 10, the amount of the modification can be based on the amount of cardiac movement associated with the current cardiac position state of patient 8. For example, the amount of the modification of the cardiac therapy parameter values associated with a first cardiac position state in which the heart 18 is relatively more caudal can be greater than the amount of the modification of the cardiac therapy parameter associated with a second cardiac position state in which the heart 18 is cranial relative to the first cardiac position state but still more caudal than the baseline position. In some instances, the positional difference of the heart 18 between such cardiac position states can be several centimeters, such as up to about 4 cm.

[0069] In some techniques where the processing circuitry of the IMD 12 can control the IMD 12 to sense an electrocardiogram of the patient 8 via a modified vector, or deliver cardiac therapy to the heart 18 via a modified electrode vector, the processing circuitry of the IMD 12 can control the system 10 to deliver cardiac therapy by controlling the IMD 12 to deliver cardiac pacing to the heart 18 via a modified vector. As discussed above, when the heart 18 is positioned caudally relative to a baseline position, such as when the patient 8 is upright and / or inhaling, one or more of the pacing / sensing electrodes 34 may no longer be approximately positioned over a portion of the heart 18 (such as the ventricles of the heart 18) to which it may be desirable to deliver pacing pulses. Instead, when the heart 18 is positioned caudally relative to a baseline position, one or more of the electrodes may be positioned over the atria of the heart 18. Pacing pulses delivered by one or more of the pacing / sensing electrodes 34 positioned over a non-target portion of the heart 18 may not contribute to pacing efficacy and may reduce the energy efficiency of the system 10. Thus, when the heart 18 is positioned caudally relative to a baseline position, it may be desirable to remove such electrodes 34 from the pacing vector, which can improve pacing efficiency.

[0070] In any of the example techniques described herein, the modification to the cardiac therapy parameters and / or the electrode vector of the system 10 can be selected by a clinician and programmed into the memory of the system 10. In some instances, the clinician can select the modification (e.g., the parameter to be modified and / or the magnitude of the modification) based on one or more physiological aspects of the patient 8, which can be associated with the amount and / or direction in which the heart 18 can move as the posture and / or respiratory state of the patient 8 changes. In some instances, the clinician can directly observe (e.g., via fluoroscopy) the amount and / or direction in which the heart 18 moves as the posture and / or respiratory state of the patient 8 changes. In such instances, since the heart 18 moves as the posture and / or respiratory state of the patient 8 changes, the processing circuitry of the IMD 12 can automatically or semi-automatically modify the values of one or more cardiac therapy parameters and / or sensing parameters, which can improve the efficacy and / or efficiency of the cardiac therapy delivered by the system 10, such as by more accurately directing energy to the target portion of the heart and / or by reducing the delivery of energy to non-target locations.

[0071] In some instances, system 10 can include an external device 38. The external device 38 can be a computing device configured for a home, outpatient, clinic, or hospital environment to communicate with the IMD 12 via wireless telemetry. Examples of communication technologies used by the IMD 12 and the external device 38 include radio frequency (RF) telemetry, which can include an RF link established via Bluetooth, a wireless local area network, or a medical implant communication service (MICS). The communication can include one-way communication, where one device is configured to send communication messages and the other device is configured to receive those messages. Alternatively or additionally, the communication can include two-way communication, where each device is configured to send and receive communication messages.

[0072] The external device 38 can include communication circuitry configured to communicate with one or more devices (e.g., IMD 12) of the system 10 according to the techniques described above. For example, when the external device 38 is configured as a programmer for the IMD 12, the external device 38 can be used to program commands or operating parameters of the IMD 12 for controlling the functions of the IMD 12. The external device 38 can be used to communicate with the IMD 12 to retrieve data such as operating data, physiological data accumulated in the IMD memory, etc. Thus, the external device 38 can function as a programmer for the IMD 12, an external monitor for the IMD 12, or a consumer device such as a smart phone. The external device 38 can be coupled to a remote patient monitoring system (such as ) available from Medtronic plc, of Dublin, Ireland. In other instances, a clinician can use the external device 38 to program or update therapy parameters that define a cardiac therapy, and / or to program and update modifications to cardiac therapy parameters, sensing parameters, and / or electrode vectors associated with multiple cardiac position states or to perform other activities with respect to the IMD 12. The clinician can be a physician, technician, surgeon, electrophysiologist, or other healthcare professional. In some instances, the user can be the patient 8.

[0073] Although described herein in the context of an example IMD 12, the techniques for controlling the delivery of the cardiac therapies described herein can be implemented using other types of IMDs configured to deliver cardiac therapies. In some instances, the techniques described herein can be implemented with an external defibrillator device or other devices or systems configured to deliver cardiac therapies. In some instances, system 10 can also include an implantable monitoring device, such as the RevealLINQ available commercially from Medtronic TM .

[0074] Figure 2 shows Figure 1A-1CFunctional block diagram of an example configuration of the IMD 12, which can be used to perform any of the techniques described with respect to Figure 1A-1C any of the techniques described herein. As Figure 2 shown, the IMD 12 includes processing circuitry 102, sensing circuitry 104, therapy delivery circuitry 106, sensors 108, communication circuitry 110, and memory 112. Additionally, the IMD 12 includes one or more electrodes 116, which can be any one or more of the previously described electrodes of the IMD 12, and one or more of the electrodes can be carried by leads 22 or disposed on the housing 20 of the IMD 12. In some instances, the memory 112 includes computer-readable instructions that, when executed by the processing circuitry 102, cause the IMD 12 and the processing circuitry 102 to perform the various functions ascribed to the IMD 12 and the processing circuitry 102 herein. The memory 112 can include any volatile, non-volatile, magnetic, optical, or dielectric, such as random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically erasable programmable ROM (EEPROM), flash memory, or any other digital medium.

[0075] The processing circuitry 102 can include fixed-function circuitry and / or programmable processing circuitry. The processing circuitry 102 can include any one or more of the following: a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or equivalent discrete or analog logic circuitry. In some instances, the processing circuitry 102 can include multiple components, such as any combination of one or more microprocessors, one or more controllers, one or more DSPs, one or more ASICs, or one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions ascribed to the processing circuitry 102 herein can be embodied as software, firmware, hardware, or any combination thereof.

[0076] In some instances, processing circuitry 102 may receive, via communication circuitry 110 (e.g., from an external device 38), respective values of multiple cardiac sensing parameters, cardiac therapy parameters (e.g., anti-tachyarrhythmia shock therapy parameters and / or cardiac pacing parameters), and / or electrode vectors. Processing circuitry 102 may store such parameters and / or electrode vectors in therapy and sensing program 118 of memory 112. Processing circuitry 102 may also receive respective modifications 122 associated with each of a plurality of cardiac position states 120 for at least one of the cardiac sensing parameters, cardiac therapy parameters, and / or electrode vectors. Processing circuitry 102 may store the cardiac position states in cardiac position states 120 of memory 112 and may store the respective modifications in modifications 122 of memory 112. The modifications may take the form of, for example, a look-up table or other data structure or function.

[0077] Processing circuitry 102 may monitor the posture and / or respiratory state of patient 8 via one or more of electrodes 116 and sensors 108. In some instances, processing circuitry 102 may determine the respiratory state of patient 8 based on the impedance between two or more of electrodes 116 (such as housing 20 of IMD 12 that may serve as a can electrode) and electrodes positioned on lead 22. Therapy delivery circuitry 106 and / or sensing circuitry 104 may include circuitry (e.g., a current or voltage source circuitry) for generating a signal having a known current or voltage amplitude, and switching circuitry for coupling the signal to a selected one of electrodes 116. Sensing circuitry 104 may include circuitry for sampling the signal and measuring the other of voltage or current. Processing circuitry 102 may determine an impedance value associated with the impedance signal based on such measurements. In other instances, processing circuitry 102 may determine the respiratory state based on a change in the amplitude of an electrogram (EGM) signal sensed by electrodes 116, which change may be associated with movement of heart 18 (which movement may occur with the respiration of patient 8).

[0078] In some instances, sensor 108 may include one or more gyroscopes and / or accelerometers. In some instances, such accelerometers may include one or more triaxial accelerometers. Signals generated by such gyroscopes and / or accelerometers may indicate the current posture of patient 8, such as an upright posture, a sitting posture, a supine or prone posture, or other postures. In some instances, the accelerometer may generate a signal that varies based on respiration, e.g., based on vibrations and / or movement associated with respiration. For example, when the implantation site of IMD 12 within patient 8 moves (e.g., tilts) with respiration, a cyclic component of the signal sensed by the accelerometer may be associated with the movement of IMD 12.

[0079] In other instances, sensor 108 can include one or more other sensors configured to determine the respiratory state of patient 8, such as a microphone configured to detect sounds associated with the breathing of patient 8, a magnetometer configured to sense movement within the Earth's magnetic field associated with the breathing of patient 8, or a pressure sensor configured to measure changes in pressure applied to lead 22 associated with changes in the respiratory state.

[0080] For example, sensing circuitry 106 can include filters, amplifiers, and / or analog-to-digital conversion circuitry to condition any of these sensed signals for analysis by processing circuitry 102 and / or to detect features of the signals. For example, sensing circuitry 106 can condition the EGM signal to extract changes in the amplitude of the EGM signal, which can be associated with movement of heart 18 (which occurs as patient 8 breathes). In instances where sensor 108 includes a microphone, sensing circuitry 106 can condition the audio signal sensed by the microphone to separate breathing sounds from interfering background noise. In instances where sensor 8 includes a pressure sensor, sensing circuitry 106 can condition the signal sensed by the pressure sensor to filter out changes caused by atmospheric pressure. In any such instance, processing circuitry 102 can determine the posture of patient 8 and / or the respiratory state of patient 8 based on signals obtained from electrodes 116 and sensor 108, and can correlate the posture and / or respiratory state of patient 8 with the current cardiac position state of heart 18 among the various cardiac position states 120 stored in cardiac position state 120 of memory 112.

[0081] In some instances, the heart position state 120 can be defined by one or more threshold postures and / or respiration values. For example, one or more of the heart position states in the heart position state 120 can be defined at least in part by a threshold respiration depth value. In such instances, the processing circuitry 102 can determine a respiration depth value associated with the respiration state of the patient 8, such as by determining the impedance between two or more of the electrodes 116 and / or analyzing signals sensed by one or more of the sensors 108, and determine the current heart position state of the heart 18 at least in part based on whether the determined respiration depth value meets the threshold respiration depth value. In instances where the heart position state is associated with a posture, the heart position state can be defined at least in part by a threshold associated with the posture. In such instances, the threshold can be a value (e.g., voltage) derived from signals sensed by one or more accelerometers of the sensor 108. For example, the sensing circuitry 106 can condition the signals sensed by one or more accelerometers (such as by applying a low-pass filter to the signals) for analysis by the processing circuitry 102. The processing circuitry 102 can then analyze the conditioned signals to determine a value associated with the current posture of the patient 8 and determine the current position state of the heart 19 at least in part based on whether the determined value meets the threshold associated with the posture.

[0082] After determining the current cardiac position state of patient 8 as one of cardiac position states 120, processing circuitry 102 may modify at least one of a cardiac sensing parameter value, a cardiac therapy parameter value, and / or an electrode vector based on one or more modifications in modifications 122 associated with the current cardiac position state. Example parameters include a cardiac pacing magnitude value (e.g., pulse amplitude or width), an anti-tachyarrhythmia shock magnitude value (e.g., pulse amplitude, pulse width, and / or shock energy), or an electrocardiogram sensing parameter, such as a threshold amplitude for detecting an R wave, a P wave, or other features of an electrocardiogram. In some instances, the parameter is a tachyarrhythmia detection parameter, which may be an electrocardiogram sensing parameter used by processing circuitry 102 to detect tachyarrhythmia. In some instances, the parameter is an electrode vector of multiple electrodes 116, and processing circuitry 102 may use the electrode vector to sense an electrocardiogram and / or deliver cardiac therapy via a modified electrode vector. Then, processing circuitry 102 may control IMD 12 to deliver cardiac therapy via therapy delivery circuitry 106 based on the modified sensing parameter value, cardiac therapy parameter value, and / or electrode vector. In some other instances, processing circuitry 102 may modify an electrode vector including at least two defibrillation electrodes of electrodes 116 or at least two pacing / sensing electrodes of electrodes 116 based on the current cardiac position state, and control IMD 12 to sense at least an electrocardiogram via electrodes 116 and sensing circuitry 104, or deliver cardiac therapy via electrodes 116 and therapy delivery circuitry 106.

[0083] In some instances, according to the techniques described above with respect to Figure 1A-1C processing circuitry 102 may modify a cardiac therapy parameter value based on one or more modifications in modifications 122 associated with the current cardiac position state of patient 8 in memory 112. For example, processing circuitry 102 modifies a cardiac therapy parameter value by modifying a tachyarrhythmia detection parameter and / or an electrocardiogram sensing amplitude threshold stored in therapy and sensing program 118 according to modifications 122 associated with the current cardiac position state 120 of patient 8. In other instances, processing circuitry 102 may modify a cardiac therapy parameter value by modifying an anti-tachyarrhythmia shock magnitude value or the amplitude of one or more pacing pulses stored in therapy and sensing program 118 according to modifications 122 associated with the current cardiac position state 120 of patient 8. In still other instances, processing circuitry 102 may modify a cardiac therapy parameter value by modifying at least one of a sensing vector of at least two pacing / sensing electrodes including electrodes 116 or a shock vector of at least two defibrillation electrodes including electrodes 116 according to a modification associated with the current cardiac position state of patient 8 in memory 112.

[0084] In some other instances, in accordance with the techniques described above with respect to Figure 1A-1C the processing circuitry 102 may control the IMD 12 to sense at least an electrocardiogram of the patient 8 via a modified electrode vector or to deliver cardiac therapy to the heart 18 via a modified electrode vector. For example, the processing circuitry 102 may modify a vector including at least two of the electrodes 116 by modifying the electrode vectors stored in the therapy and sensing program 118 in accordance with a modification 122 associated with the current cardiac position state 120 of the patient 8.

[0085] In any such instance, the processing circuitry 102 may also control the IMD 12 to sense an electrocardiogram or deliver cardiac therapy (e.g., an anti - tachyarrhythmia shock or cardiac pacing) via the electrodes 116 and the sensing circuitry 104 or the therapy delivery circuitry 106 based on one or more of the modified sensing parameter values, cardiac therapy parameter values, or modified electrode vectors. Thus, the processing circuitry 102 may improve the efficacy and / or efficiency of the cardiac therapy delivered by the system 10, such as by more accurately directing energy to the target portion of the heart and / or by reducing the delivery of energy to non - target locations.

[0086] Based on one or more factors such as the gender, age, size, or observed cardiac motion of the patient 8, as via an external device 38 or a remote computer, a clinician may input one or more of the therapy and sensing program 118, the cardiac position state 120, or the modification 122 into the memory 112, or the processing circuitry 102 itself may determine and recommend them. The factors may be provided to the processing circuitry 102 by the clinician, for example, via the external device 38. In some instances, the clinician and / or the processing circuitry 102 may update one or more of the therapy and sensing program 118, the cardiac position state 120, or the modification 122 periodically or as needed. For example, the clinician or the processing circuitry 102 may determine that the magnitude of one or more modifications in the modification 122 does not effectively counteract a reduction in the efficacy or efficiency of the cardiac therapy associated with a particular cardiac position state in the cardiac position state 120, based on data stored in the diagnosis / feedback 124 of the memory 112. In some such instances, the clinician may input one or more updated values of the modification 122 into the external device 38 or the remote computer, or the processing circuitry 102 may recommend updated values via the external device 38. The processing circuitry 102 may then receive the updated modification 122 (or, in other instances, the updated therapy and sensing program 118 and / or cardiac position 120) from the external device 38 or the remote computer and may store such updated values in the memory 112.

[0087] Diagnostics / feedback 124 of memory 112 may include data related to one or more of the following: the determined cardiac position status of patient 8, the determined posture and / or respiratory status of patient 8, or the efficacy or efficiency of cardiac therapies delivered by IMD 12. For example, diagnostics / feedback 124 may store efficacy determinations made by processing circuitry 102 based on whether cardiac therapies delivered by IMD 12 according to one or more modified cardiac therapy parameter values and associated with one of cardiac position states 120 successfully terminated tachyarrhythmias or maintained pacing capture. Diagnostics / feedback 124 may also store efficiency determinations made by processing circuitry 102 based on data related to, for example, the amount of energy delivered to treat tachyarrhythmias or maintain pacing capture when processing circuitry 102 controls IMD 12 to deliver cardiac pacing according to one or more cardiac therapy parameter values and associated with one of cardiac position states 120. In some instances, a clinician may view such efficacy and / or efficiency determinations stored in diagnostics / feedback 124 and use this data to determine whether to update one or more of therapy and sensing program 118, cardiac position 120, or modification 122. In some instances, diagnostics / feedback 124 may store system diagnostics related to the function of IMD 12 or other components of the medical device system that includes IMD 12.

[0088] Therapy and sensing program 118 may include values of one or more therapy and sensing parameters. In some instances, one of therapy and sensing programs 118 may correspond to a type of cardiac therapy, such as anti-tachyarrhythmia shock therapy or cardiac pacing therapy. For example, one therapy and sensing program in therapy and sensing program 118 may include values of one or more sensing parameters and one or more therapy parameters that may be suitable for sensing the heart rate of patient 8 during cardiac pacing therapy and delivering cardiac pacing therapy to heart 18, such as a sensing amplitude threshold, a pacing pulse amplitude or width, a sensing or pacing electrode vector, or a pulse delivery timing. For example, another therapy and sensing program in therapy and sensing program 118 may include values of one or more sensing parameters and one or more therapy parameters that may be suitable for sensing the heart rate of patient 8 during tachyarrhythmia detection and delivering anti-tachyarrhythmia therapy to heart 18, such as a tachyarrhythmia sensing amplitude threshold, an anti-tachyarrhythmia shock magnitude, a tachyarrhythmia sensing electrode vector or a defibrillation electrode vector, or an anti-tachyarrhythmia shock delivery timing.

[0089] The sensing circuit system 104 and the therapy delivery circuit system 106 can be selectively coupled to the electrode 116, for example, by a switching circuit system (not shown) controlled by the processing circuit system 102. The switching circuit system can include one or more transistors or other circuit systems for selectively coupling the electrode 116 to other circuit systems of the IMD 12. The sensing circuit system 104 can monitor signals from the electrode 116 to monitor the electrical activity of the heart (e.g., detect depolarization for heart rate determination and / or generate an electrocardiogram for morphology or other analysis). The sensing circuit system 104 (or the therapy delivery circuit system 106) can also generate signals through the electrode 116. The sensing circuit system 104 can generate a thoracic impedance signal from the electrode, and the sensing circuit system 104 and / or the processing circuit system 102 can sense respiration from the electrode, e.g., magnitude and / or rate. The sensing circuit system 104 can also monitor signals from one or more other sensors 108, such as one or more accelerometers, gyroscopes, magnetometers, barometers, or other sensors configured to determine the posture and / or respiratory state of the patient 8. The sensing circuit system 104 can monitor signals from any electrode or other sensor that can be located on the IMD 12 or on another device in communication with the IMD 12. In some instances, the sensing circuit system 104 can include one or more filters and amplifiers for filtering and amplifying signals received from one or more of the electrode 116 and / or one or more of the sensors 108. The sensing circuit system 104 can also include a rectifying circuit system, a sample-and-hold circuit system, one or more comparators, and / or an analog-to-digital conversion circuit system. The functions provided by this circuit system can be applied to signals in the analog or digital domain.

[0090] The therapy delivery circuit system 106 can include a circuit system for generating signals (such as one or more capacitors, charge pumps, and / or current sources) and a circuit system for selectively coupling the signals to the electrode 116 (e.g., transistors or other switching circuit systems).

[0091] The communication circuitry 110 can include any suitable hardware, firmware, software, or any combination thereof for communicating with another device (such as an external device 38) or another IMD or sensor (such as a pressure sensing device). For example, the communication circuitry 110 can include a voltage regulator, a current generator, an oscillator or circuitry for generating signals, resistors, capacitors, inductors, and other filtering circuitry for processing received signals, and circuitry for modulating and / or demodulating signals according to a communication protocol. The communication circuitry 110 can also include transistors or other switching circuitry (e.g., in the case of tissue conduction communication (TCC)) for selectively coupling a transmitted signal to an antenna (not shown) of the IMD 12 or an electrode 116 or receiving signals from the antenna or the electrode. Under the control of the processing circuitry 102, the communication circuitry 110 can receive downlink telemetry from the external device 38 or another device and transmit uplink telemetry thereto. In some instances, the communication circuitry 110 can communicate with the external device 38. Additionally, the communication circuitry 110 can communicate with a networked computing device through an external device (e.g., the external device 38) and a computer network (such as the Medtronic network developed by Medtronic, Inc. of Dublin, Ireland), as further described below with respect to Figure 3 further description.

[0092] A clinician or another user can use the external device 38 or retrieve data from the IMD 12 by using another local or networked computing device configured to communicate with the processing circuitry 102 through the communication circuitry 110 (e.g., a remote computer located with the clinician). In some instances, the clinician can also use the external device 38 or another local or networked computing device to program parameters of the IMD 12. For example, the clinician can update the heart position status 120, modify 122, and / or values associated with the therapy and sensing program 118.

[0093] Although the processing circuitry 102 of the IMD 12 was described above as being configured to receive signals from the sensor 108, determine the current cardiac position state of the patient 8, modify at least one cardiac therapy parameter value, cardiac sensing parameter value, and / or electrode vector based on the modification 122 associated with the current cardiac position state, and control the IMD 12 to deliver cardiac therapy and / or sense an electrocardiogram based on the modified at least one cardiac therapy parameter value, modified cardiac sensing parameter value, or modified electrode vector, and to perform other steps of the techniques described herein, any step performed by the processing circuitry 102 of the IMD 12 described herein may be performed by the processing circuitry of one or more other devices. For example, the processing circuitry of an external device 38, a remote computer, or any other suitable implantable or external device or server may be configured to perform one or more of the steps of the techniques described herein as performed by the communication circuitry 110 of the IMD 12.

[0094] Figure 3 is a functional block diagram showing an example system that includes an access point 160, a network 162, an external computing device such as a server 164, and one or more other computing devices 170A - 170N, which may be coupled to Figure 2 the IMD 12 and the external device 38 via the network 162. In this example, the IMD 12 may communicate with the external device 38 via a first wireless connection using the communication circuitry 110 and communicate with the access point 160 via a second wireless connection. In Figure 3 this example, the access point 160, the external device 38, the server 164, and the computing devices 170A - 170N are interconnected and may communicate with each other via the network 162.

[0095] Access point 160 may include means for connecting to network 162 via any of a variety of connections, such as a telephone dial-up, Digital Subscriber Line (DSL), or cable modem, or other suitable connection. In other instances, access point 160 may be coupled to network 162 via different forms of connection, including wired or wireless connections. In some instances, access point 160 may be a user device that can be co-located with a patient, such as a tablet or smartphone. In some instances, IMD 12 may be configured to send data, such as cardiac therapy delivery efficacy and / or efficiency data stored in diagnostic / feedback 124 of memory 112, to external device 38. Additionally, access point 160 may interrogate IMD 12, such as periodically or in response to a command from patient 8, a clinician, or network 162, to retrieve therapy and sensing program 118, cardiac location status 120, modifications 122, diagnostic / feedback 124, or other information stored in memory 112 of IMD 12. Access point 160 may then transmit the retrieved data to server 164 via network 162.

[0096] In some cases, server 164 may be configured to provide a secure storage site for data collected from IMD 12 and / or external device 38. In some cases, server 164 may compile the data in a web page or other document for viewing by trained professionals, such as clinicians, via computing devices 170A - 170N. One or more aspects of the system shown may be implemented using general network technologies and capabilities, which may include or be similar to the general network technologies and capabilities provided by the Medtronic Figure 3 network developed by Medtronic, Inc., of Dublin, Ireland. In some instances, the network technologies and capabilities may authenticate communications sent to IMD 12 from a device, such as a device claiming to be one of computing devices 170A - 170N (e.g., a claimed remote computer co-located with a clinician). In some instances, such security features may protect the cardiac therapy delivered by IMD 12 to patient 8 from interference, intrusion, or otherwise being altered by communications from unauthorized sources.

[0097] In some instances, one or more of the computing devices 170A - 170N (e.g., device 170A) can be a remote computer, such as a smart phone, a tablet, or other smart device located with a clinician, through which the clinician can program and receive alerts and / or interrogate the IMD 12. For example, when the patient 8 is between clinician visits, such as to examine one or more aspects of the cardiac therapy delivered by the IMD 12, the clinician can access patient requests, symptoms, undesired effects, and / or efficacy indications as needed through device 170A. In some instances, the clinician can input medical instructions for the patient 8 into an application in device 170A based on data retrieved from the IMD 12 through device 170 or based on other patient data known to the clinician, such as instructions to schedule an appointment with the clinician for the patient 8 or to seek other medical care for the patient 8. Then, device 170A can send instructions for medical intervention to a receiving device located with the patient 8.

[0098] Figures 4-6 is a flow chart showing various example techniques in accordance with examples of the present disclosure, the various example techniques being related to controlling the delivery of cardiac pacing to the heart 18 by the IMD 12 in accordance with required values of therapy parameters. As described herein, the IMD 12 and an external device (e.g., Figure 1A external device 38) can be used in combination with the patient 8 as described above with respect to Figure 2 and 3 using the example techniques shown in Figures 4-6 . Although described as being performed by the IMD 12, the Figures 4-6 techniques can be performed in whole or in part by the processing circuitry and memory of other devices of the medical device system, as described herein. For example, although the processing circuitry 102 of the IMD 12 is described as performing most of the example techniques shown in Figures 4-6 for clarity, in other instances, one or more devices (e.g., a remote computer or other external device or server located with the clinician) can perform one or more steps attributed herein to the processing circuitry 102 of the IMD 12.

[0099] Figure 4 is a flow chart showing example techniques for the purpose of determining corresponding modifications of at least one therapy or sensed parameter associated with each of a plurality of cardiac position states. In Figure 4In an example technique, the processing circuitry 102 can determine the cardiac position state (180) of the patient 8 for each of a plurality of postures and / or each of a plurality of respiratory states, such as by receiving from an external device 38 or another external device one or more indications of the patient's 8 posture and / or respiratory state for which the system 10 is to modify therapy and / or sensing parameters.

[0100] For each of the plurality of cardiac position states, the processing circuitry 102 then determines the difference (182) between the cardiac position state and a baseline cardiac position state. In some instances, the baseline cardiac position state can be the position of the heart 18 when the patient 8 is supine and not taking rapid deep breaths or inhaling. Each of the plurality of cardiac position states can differ from the baseline cardiac position state by the magnitude of the distance between a portion (e.g., the apex) of the heart 18 in the baseline state and the portion of the heart in the cardiac position state. In some instances, the processing circuitry 102 can determine the distance as a distance in a single plane (e.g., the transverse plane), or a distance in more than one plane (e.g., the transverse plane and the anterior plane).

[0101] Next, for each of the plurality of cardiac position states, the processing circuitry 102 determines one or more corresponding modifications (184) of one or more of the sensing parameters, therapy delivery parameters, and / or electrode vectors based on the difference between the cardiac position state and the baseline cardiac position. In some instances, the magnitude of the modification of the cardiac therapy parameters determined by the processing circuitry 102 can correspond to the magnitude of the difference between the cardiac position state and the baseline cardiac position. For example, a cardiac position state in which the heart 18 is relatively far from the baseline cardiac position can be associated with a modification of the cardiac therapy parameters that is greater than the modification of the same cardiac therapy parameters associated with a cardiac position state that is relatively closer to the baseline cardiac position.

[0102] Next, for each of the plurality of cardiac position states, the processing circuitry 102 stores the determined one or more corresponding modifications of one or more of the therapies or sensed in the memory of the system 10, such as in the modification 122 of the memory 112 of the IMD 12 (186). In some instances, the processing circuitry 102 can store such modifications associated with a particular cardiac position state in the memory 112. For example, the processing circuitry 102 can store modifications of the tachyarrhythmia detection parameters and the magnitude of the antitachyarrhythmia shock associated with a particular cardiac position state (such as a cardiac position state in which the heart 18 is caudal relative to the baseline position). In other instances, the processing circuitry can store a single modification of one or more of the therapy or sensing parameters associated with the cardiac position state in the memory 112.

[0103] Figure 5 is a flowchart showing example techniques for: modifying at least one therapy or sensed parameter value based on a modification associated with a current cardiac position state of the heart 18 upon determining that the cardiac position state of the heart 18 has changed. In Figure 5 the example technique of, processing circuitry 102 may determine a current position state (190) of the heart 18 of the patient 8. For example, as discussed above with respect to Figure 1A-2 , the processing circuitry 102 may determine the current position state of the heart 18 based on one or more of the patient 8's current posture or current respiratory state, and the processing circuitry 102 may, as described above with respect to Figure 2 , determine the current posture or current respiratory state based on signals received from electrodes of the system 10 (e.g., pacing / sensing electrode 34 or sensing electrodes of electrode 116) or one or more sensors 108.

[0104] Next, the processing circuitry 102 determines whether the cardiac position state of the heart 18 has changed (192). In some instances, the processing circuitry 102 may determine whether the cardiac position state of the heart 18 has changed relative to a baseline cardiac position state described above (e.g., with respect to Figure 4 ). In other instances, the processing circuitry 102 may determine whether the cardiac position state of the heart 18 has changed relative to a previously determined cardiac position state of the heart 18 determined by the processing circuitry 102 (such as the most recently determined cardiac position state). In either instance, if the processing circuitry 102 determines that the cardiac position state of the heart 18 has changed (''Yes'' at 192), then the processing circuitry 102 modifies one or more of the cardiac therapy parameter values, sensed parameters, or electrode vectors according to a modification 122 associated with the current cardiac position state of the heart 18 in the memory 112 (194).

[0105] If the processing circuitry 102 determines that the cardiac position state of the heart 18 has not changed ("No" at 192), then the processing circuitry 102 returns to (190) and again determines the current cardiac position state of the heart 18 (e.g., an updated cardiac position state of the heart 18) (194). In some instances, the processing circuitry 102 may determine the current cardiac position state of the heart 18 multiple times during each respiratory cycle of the patient 8. For example, the processing circuitry 102 may determine the current cardiac position of the heart 18 during the inspiratory and expiratory phases of the respiratory cycle. In other instances, the processing circuitry 102 may determine the current cardiac position of the heart 18 according to a different timing arrangement (e.g., during a predetermined length of time at a predetermined interval). In some instances, the processing circuitry 102 may determine the respiratory state of the patient 8 more frequently than the patient 8's posture. For example, the cardiac position state of the heart 18 may change more frequently due to the respiratory state of the patient 8 than due to the posture state of the patient 8. In such instances, whenever the processing circuitry 102 determines the current respiratory state of the patient 8, the processing circuitry 102 may determine the cardiac position state of the heart 18 regardless of whether the processing circuitry 102 has substantially simultaneously determined a new posture state of the patient 8. In any such instance, when the clinician programs other data into the memory 112 (e.g., as described above with respect to Figure 2 ), the clinician may program an interval into the memory 112 at which the processing circuitry 102 may determine one or more of the posture, respiratory state, or cardiac position state.

[0106] Figure 6 is a flowchart showing an example technique for the purpose of modifying electrode vectors based on determining that the cardiac position state of the heart 18 has changed. In Figure 6 the example technique, the processing circuitry 102 may determine the current position state of the heart 18 of the patient 8 (200), as described above with respect to Figure 5 . Next, the processing circuitry 102 determines whether the cardiac position state of the heart 18 corresponds to one or more of an upright posture, inspiration, deep inspiration, or any other posture and / or respiratory state associated with the heart 18 being located in a relatively lower position within the chest cavity of the patient 8 (202). If the processing circuitry 102 determines that the cardiac position state of the heart 18 corresponds to one or more of an upright posture, inspiration, deep inspiration, or any other posture and / or respiratory state associated with the heart 18 being located in a relatively lower position within the chest cavity of the patient 8 ("Yes" at 202), then the processing circuitry 102 modifies the electrode vector (e.g., a sensing vector, a pacing vector, or an anti-tachyarrhythmia vector) according to a modification 122 associated with the current cardiac position state of the heart 18 in the memory 112 (204).

[0107] If the processing circuitry 102 determines that the cardiac position state of the heart 18 does not correspond to one or more of an upright posture, inspiration, deep breathing, or any other posture and / or respiratory state associated with a relatively lower position of the heart 18 located in the thoracic cavity of the patient 8 ( "no" at 202), then the processing circuitry 102 returns to (200) and, as described above with respect to Figure 5 the manner described, again determines the current cardiac position state of the heart 18 (e.g., an updated current cardiac position state of the heart 18). In this manner, the processing circuitry 102 can enable the system 10 to more accurately sense one or more aspects of cardiac electrical signals and / or deliver more effective and / or efficient cardiac therapy to the heart 18. In any such instance, improving sensing accuracy or the efficacy and / or efficiency of cardiac therapy delivery can advantageously improve one or more of the clinical outcome of the patient 8 or the lifespan of the power source of the system 10.

[0108] Although the processing circuitry 102 of the IMD 12 has been described above as configured to perform one or more of the steps of the techniques described with respect to FIGS. 1-6, any of the steps of the techniques described herein can be performed by the processing circuitry of other devices. For example, the processing circuitry of a remote computer (e.g., computing device 170A) located with a clinician or any other suitable implantable or external device or server can be configured to perform one or more of the steps described as being performed by the processing circuitry 102 of the IMD 12. Such other implantable or external devices can include, for example, implantable or external monitoring devices or any other suitable devices.

[0109] Aspects of the techniques can be implemented within one or more processors, the one or more processors including one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combination of such components, embodied in a programmer such as a physician or patient programmer, an electrical stimulator, or other device. The term "processor" or "processing circuitry" can generally refer to any of the foregoing logic circuitry or any other equivalent circuitry, alone or in combination with other logic circuitry.

[0110] In one or more instances, the functions described in this disclosure may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium and executed by a hardware-based processing unit. The computer-readable medium may include a computer-readable storage medium that forms a tangible non-transitory medium. The instructions may be executed by one or more processors, such as one or more DSPs, ASICs, FPGAs, general-purpose microprocessors, or other equivalent integrated or discrete logic circuitry. Thus, as used herein, the term "processor" or "processing circuitry" may refer to any of the foregoing structures or one or more of any other structure suitable for implementing the techniques described herein.

[0111] Additionally, in some aspects, the functions described herein may be provided within dedicated hardware and / or software modules. Depicting different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be implemented by separate hardware or software components. Instead, the functions associated with one or more modules or units may be performed by separate hardware or software components, or may be integrated within common or separate hardware or software components. Moreover, the techniques may be implemented entirely within one or more circuits or logic elements. The techniques of this disclosure may be implemented in a variety of apparatuses or devices, including IMDs, external programmers, combinations of IMDs and external programmers, integrated circuits (ICs) or groups of ICs, and / or discrete circuitry located within IMDs and / or external programmers.

[0112] Experimental results

[0113] This disclosure includes the following discussion, which forms a part of this disclosure. The following discussion may provide many details and examples consistent with this disclosure. As further described below, one or more studies and experiments were conducted to evaluate one or more aspects of the examples of this disclosure. However, this disclosure is not limited by the studies and experiments.

[0114] For example, the details and examples discussed below may be based on respiration and posture to quantify changes in cardiac signal sensing by an EV-ICD. Modeling in such examples may similarly be used to quantify changes in pacing and / or anti-tachyarrhythmia shock parameters expected in response to changing posture and respiratory states to obtain therapeutic benefits by efficiently utilizing power resources. The following examples may also further illustrate the movement of the heart as posture and respiratory states change, and the effect of such movement on the position of the heart relative to the electric fields generated by pacing and / or shock therapy using more upper / distal electrodes.

[0115] In some instances, the EV ICD uses defibrillation leads placed external to the heart in the anterior mediastinal space. In this location, the electrodes can have some freedom of movement relative to the heart as posture changes. The extent to which this movement affects the electrograms obtained by the electrodes in this new implant location has not been systematically characterized. A study was conducted to quantify the changes in the sensed signals due to posture and respiratory changes.

[0116] The first modeling study used a set of MRI scans obtained in various postures and respiratory states to derive anthropometric data that quantified organ movement and shape relative to the supine, end-inspiratory posture representing the implant condition. Detailed data on key anatomical structures such as the heart and epicardial fat were obtained from high-resolution ex vivo MRI scans and fused with lower-resolution MRI to create an anatomical structure with an appropriate level of detail for accurate simulation. A matching set of computational grids representing the object with various postures was created, and then the ICD was "implanted" multiple times into the matching locations for these postures. The epicardial potentials were estimated separately from the body surface recordings and mapped onto the myocardial surface.

[0117] Figure 7 Figure shows four MRI scans (top) and corresponding models (bottom) that illustrate the position of the patient's heart within the patient (e.g., within the thorax) during inspiration (INH) in the supine (SUP), left decubitus (LD), right decubitus (RD), and upright (UP) postures. As shown, the relative position of the patient's heart is different for each different posture. In one patient, a 20-mm cranio-caudal movement of the heart was observed during tidal breathing and a 60-mm movement during deep breathing.

[0118] The epicardial potential data were manually annotated by identifying scoring windows for various types of heartbeats such as normal sinus rhythm (NSR) or ventricular tachycardia (VT). An automated system calculated the cardiac signals at the electrodes of the ICD for more than 2000 data sets, automatically scored them, and stored these results in a database for statistical analysis.

[0119] It was found from the motion analysis of the MRI image data that the average cranio-caudal movement of the cardiac apex was 34 mm (range: 3 to 70 mm, N = 9). For four combinations of supine (SUP), upright (UP), inspiration (INH), and expiration (EXH) represented by SUP-INH, SUP-EXH, UP-INH, and UP-EXH, Figure 8An example of a predictive signal with a scoring window is shown. In this single example, the baseline-to-peak amplitude (in millivolts (mVpk)) of the NSR complex wave ranges from 1.46 to 2.09 mVpk, while that of the VT complex wave ranges from 0.75 to 2.22 mVpk. For both complex waves, the minimum amplitude is associated with the supine exhalation posture (SUP-EXH), and the maximum amplitude is associated with the upright inhalation posture (UP-INH).

[0120] The modeling results can be used to evaluate both signal amplitude and postural stability. The results are also used to test the criteria for device and lead implantation locations to ensure sufficient signal levels for successful arrhythmia detection in all postures. Incorporating postural variations is crucial for ensuring the dynamic performance of an EV ICD with electrodes located outside the heart.

[0121] Figure 9A and 9B are conceptual diagrams of MRI images of a patient's heart 102 and an EV ICD 104 in the supine posture ( Figure 9A ) and the upright posture ( Figure 9B ) during inhalation. Figure 9A and 9B The shaded regions in both indicate the high current density regions where defibrillation therapy is delivered using the defibrillation vector D1, which includes a can electrode in combination with at least one lead electrode. As shown, during standing and during inhalation, the heart 102 moves caudally, as indicated by the arrows between the images. In some instances, this may cause the defibrillation vector D1 to become less effective during defibrillation. Thus, for some cases, defibrillation efficacy can be improved by sensing the upright posture and disabling the vector (e.g., vector D1), increasing the defibrillation energy, or both, in response to sensing the upright posture.

[0122] Figure 10 is a graph showing the variation of the DFT with posture and respiration for various modeled patients. The stability graph compares the defibrillation threshold (DFT) in the supine inhalation case (X-axis) with the values in all other postures (Y-axis). For some patients (HB-F-004-A and HB-F-004-B), the DFT is stable with respect to posture, while for other patients (HB-M-005-A and HB-M-005-B), the DFT may vary significantly. It is believed that patients with an unstable DFT may benefit from a device that increases the shock energy when it senses that the patient is in a determined problematic posture.

[0123] Various aspects of the present disclosure have been described. These and other aspects are within the scope of the following claims and clauses.

[0124] Clause 1. A method for controlling the delivery of anti-tachyarrhythmia shock therapy through a medical device system, the medical device system including a plurality of electrodes for delivering the anti-tachyarrhythmia shock therapy, the method including: storing in a memory of the medical device system corresponding values for each of a plurality of anti-tachyarrhythmia shock therapy parameters, and corresponding modifications associated with each of a plurality of cardiac position states for at least one of the anti-tachyarrhythmia shock therapy parameters; and by a processing circuitry of the medical device system: determining a current cardiac position state of the plurality of cardiac position states of the patient; modifying the at least one anti-tachyarrhythmia shock therapy parameter value according to the modification associated with the current cardiac position state; and controlling the delivery of the anti-tachyarrhythmia shock therapy according to the modified at least one anti-tachyarrhythmia shock therapy parameter value.

[0125] Clause 2. The method according to Clause 1, further including delivering the anti-tachyarrhythmia shock therapy through a therapy delivery circuitry of the medical device system according to the modified at least one anti-tachyarrhythmia shock therapy parameter value.

[0126] Clause 3. The method according to Clause 1 or 2, wherein the medical device system includes a medical electrical lead, the medical electrical lead including a proximal end coupled to an implantable cardioverter-defibrillator and a distal portion including at least one of the plurality of electrodes, the distal portion being substantially implanted within the anterior mediastinum of the patient.

[0127] Clause 4. The method according to any one of Clauses 1 to 3, wherein the plurality of cardiac position states includes a plurality of postures of the patient.

[0128] Clause 5. The method according to any one of Clauses 1 to 4, wherein determining the current cardiac position state of the patient includes determining at least one of a respiratory phase, a respiratory rate, or a respiratory depth of the patient.

[0129] Clause 6. The method according to any one of Clauses 1 to 5, wherein modifying the at least one anti-tachyarrhythmia shock therapy parameter value includes modifying a tachyarrhythmia detection parameter.

[0130] Clause 7. The method according to Clause 6, wherein modifying the tachyarrhythmia detection parameter includes modifying a cardiac electrogram sensing amplitude threshold.

[0131] Clause 8. The method according to any one of Clauses 1 to 7, wherein modifying the at least one anti-tachyarrhythmia shock therapy parameter value includes modifying an anti-tachyarrhythmia shock magnitude.

[0132] Clause 9. The method according to any one of Clauses 1 to 8, wherein the plurality of anti-tachyarrhythmia shock therapy parameters include a sensing vector and a shock vector, the sensing vector includes at least two of the plurality of electrodes, the shock vector includes at least two of the plurality of electrodes, and wherein modifying the value of the at least one anti-tachyarrhythmia shock therapy parameter includes modifying at least one of the sensing vector or the shock vector.

[0133] Clause 10. The method according to Clause 9, wherein modifying at least one of the sensing vector or the shock vector includes removing one of the at least two of the plurality of electrodes from at least one of the sensing vector or the shock vector.

[0134] Clause 11. The method according to Clause 10, wherein removing one of the at least two of the plurality of electrodes includes removing the uppermost one of the at least two of the plurality of electrodes.

[0135] Clause 12. The method according to Clause 11, wherein the distal portion of the medical electrical lead includes the at least two of the plurality of electrodes, and wherein removing the uppermost one of the at least two of the plurality of electrodes includes removing the most distal one of the at least two of the plurality of electrodes.

[0136] Clause 13. The method according to Clause 11, wherein determining the cardiac position state of the patient includes at least one of the following: determining that the patient is in an upright position; or determining that the respiratory state of the patient includes at least one of an inspiratory phase, a respiratory depth that meets a respiratory depth threshold, or a respiratory rate that meets a respiratory rate threshold.

[0137] Clause 14. A medical device system for delivering anti-tachyarrhythmia shock therapy, the system comprising: a plurality of electrodes; a memory configured to store a respective value for each of a plurality of anti-tachyarrhythmia shock therapy parameters, and a respective modification associated with each of a plurality of cardiac position states for at least one of the anti-tachyarrhythmia shock therapy parameters; and a processing circuitry configured to: determine a current cardiac position state among the plurality of cardiac position states of the patient; modify the value of the at least one anti-tachyarrhythmia shock therapy parameter according to the modification associated with the current cardiac position state; and control the delivery of the anti-tachyarrhythmia shock therapy through the electrodes according to the modified value of the at least one anti-tachyarrhythmia shock therapy parameter.

[0138] Clause 15. The medical device system according to Clause 14 further includes a therapy delivery circuitry configured to deliver the anti-tachyarrhythmia shock therapy through the electrodes according to the at least one modified anti-tachyarrhythmia shock therapy parameter value.

[0139] Clause 16. The medical device system according to Clause 14 or 15 further includes: an implantable cardioverter-defibrillator; and a medical electrical lead including a proximal end coupled to the implantable cardioverter-defibrillator and a distal portion including at least one of the plurality of electrodes, the distal portion being configured for substantially implanting into the anterior mediastinum of the patient.

[0140] Clause 17. The medical device system according to any one of Clauses 14 to 16, wherein the plurality of cardiac position states includes a plurality of postures.

[0141] Clause 18. The medical device system according to any one of Clauses 14 to 17, wherein the processing circuitry is configured to determine the current cardiac position state of the patient by at least determining at least one of a respiratory period, a respiratory rate, or a respiratory depth of the patient.

[0142] Clause 19. The medical device system according to any one of Clauses 14 to 18, wherein the processing circuitry is configured to modify the at least one anti-tachyarrhythmia shock therapy parameter value by at least modifying a tachyarrhythmia detection parameter.

[0143] Clause 20. The medical device system according to Clause 19, wherein the processing circuitry is configured to modify the tachyarrhythmia detection parameter by at least modifying an electrocardiogram sensing amplitude threshold.

[0144] Clause 21. The medical device system according to any one of Clauses 14 to 20, wherein the processing circuitry is configured to modify the at least one anti-tachyarrhythmia shock therapy parameter value by at least modifying an anti-tachyarrhythmia shock magnitude.

[0145] Clause 22. The medical device system according to any one of Clauses 14 to 21, wherein the plurality of anti-tachyarrhythmia shock therapy parameters includes a sensing vector and a shock vector, the sensing vector includes at least two of the plurality of electrodes, the shock vector includes at least two of the plurality of electrodes, and wherein the processing circuitry is configured to modify the at least one anti-tachyarrhythmia shock therapy parameter value by at least modifying at least one of the sensing vector or the shock vector.

[0146] Clause 23. The medical device system according to Clause 22, wherein the processing circuitry is configured to modify at least one of the sensing vector or the shock vector by removing at least one of the at least two electrodes from at least one of the sensing vector or the shock vector.

[0147] Clause 24. The medical device system according to Clause 23, wherein the processing circuitry is configured to remove one of the at least two electrodes from the plurality of electrodes by removing at least the uppermost one of the at least two electrodes from the plurality of electrodes.

[0148] Clause 25. The medical device system according to Clause 24, wherein the distal portion of the medical electrical lead includes the at least two electrodes of the plurality of electrodes, and wherein the processing circuitry is configured to remove the uppermost one of the at least two electrodes from the plurality of electrodes by removing at least the most distal one of the at least two electrodes from the plurality of electrodes.

[0149] Clause 26. The medical device system according to Clause 24, wherein the processing circuitry is configured to determine the cardiac position state of the patient by at least one of: determining that the patient is in an upright position; or determining that the respiratory state of the patient includes an inspiration phase, a respiratory depth that meets a respiratory depth threshold, or a respiratory rate that meets a respiratory rate threshold.

[0150] Clause 27. A method for controlling cardiac electrogram sensing or delivery of cardiac therapy by an implantable medical device system including a plurality of electrodes, the method comprising, by processing circuitry of the medical device system: determining a cardiac position state of a patient; modifying a vector including at least two electrodes of the plurality of electrodes based on the determined cardiac position state; and controlling the medical device system to sense at least a cardiac electrogram or deliver cardiac therapy through the modified vector including the at least two electrodes of the plurality of electrodes.

[0151] Clause 28. The method according to Clause 27, further comprising delivering the cardiac therapy through the modified vector including the at least two electrodes of the plurality of electrodes by a therapy delivery circuitry of the medical device system.

[0152] Clause 29. The method according to Clause 27 or 28, wherein the medical device system includes a medical electrical lead that includes a proximal end coupled to an implantable medical device and a distal portion that includes the at least two electrodes of the plurality of electrodes, the distal portion being substantially implanted within the anterior mediastinum of the patient.

[0153] Clause 30. The method according to Clause 29, wherein the implantable medical device includes an implantable cardioverter-defibrillator, and the plurality of electrodes includes a plurality of electrodes for delivering anti-tachyarrhythmia shock therapy, wherein the cardiac therapy includes the anti-tachyarrhythmia shock therapy, and wherein controlling the medical device system to deliver cardiac therapy through the modified vector including at least two of the plurality of electrodes includes controlling the medical device system to deliver the anti-tachyarrhythmia shock therapy.

[0154] Clause 31. The method according to Clause 29, wherein the cardiac therapy includes cardiac pacing, and wherein controlling the medical device system to deliver cardiac therapy through the modified vector including at least two of the plurality of electrodes includes controlling the medical device system to deliver the cardiac pacing.

[0155] Clause 32. The method according to any one of Clauses 27 to 31, wherein the plurality of cardiac position states includes a plurality of postures of the patient.

[0156] Clause 33. The method according to any one of Clauses 27 to 32, wherein determining the current cardiac position state of the patient includes determining at least one of the respiratory phase, respiratory rate, or respiratory depth of the patient.

[0157] Clause 34. The method according to any one of Clauses 27 to 32, wherein modifying the vector including at least two of the plurality of electrodes based on the determined cardiac position state includes removing one of the at least two of the plurality of electrodes from the vector.

[0158] Clause 35. The method according to Clause 34, wherein removing one of the at least two of the plurality of electrodes from the vector includes removing the uppermost one of the at least two of the plurality of electrodes.

[0159] Clause 36. The method according to Clause 35, wherein determining the cardiac position state of the patient includes at least one of the following: determining that the patient is in an upright posture; or determining that the respiratory state of the patient includes at least one of an inhalation phase, a respiratory depth satisfying a respiratory depth threshold, or a respiratory rate satisfying a respiratory rate threshold.

[0160] Clause 37. The method according to any one of Clauses 27 to 36, the method further comprising: storing in a memory of the medical device system corresponding values for each of a plurality of cardiac therapy parameters, and corresponding modifications associated with each of a plurality of cardiac position states for at least one of the cardiac therapy parameters; and modifying the at least one cardiac therapy parameter value according to the modification associated with the cardiac position state of the patient, wherein controlling the medical device system to deliver the cardiac therapy by the modified vector including the at least two of the plurality of electrodes includes controlling the delivery of the cardiac therapy according to the modified at least one cardiac therapy parameter value.

[0161] Clause 38. The method according to Clause 37, wherein modifying the at least one cardiac therapy parameter value includes modifying a tachyarrhythmia detection parameter.

[0162] Clause 39. The method according to Clause 38, wherein modifying the tachyarrhythmia detection parameter includes an electrocardiogram sensing amplitude threshold.

[0163] Clause 40. The method according to Clause 37, wherein modifying the at least one cardiac therapy parameter value includes modifying an anti-tachyarrhythmia shock magnitude value.

[0164] Clause 41. The method according to Clause 37, wherein modifying the at least one cardiac therapy parameter value includes modifying an anti-tachyarrhythmia pacing parameter.

[0165] Clause 42. A medical device system for controlling electrocardiogram sensing or delivery of cardiac therapy, the system including a plurality of electrodes; and processing circuitry configured to: determine a cardiac position state of a patient; modify a vector including at least two of the plurality of electrodes based on the determined cardiac position state; and control the medical device system to sense an electrocardiogram or deliver cardiac therapy by the modified vector including the at least two of the plurality of electrodes.

[0166] Clause 43. The medical device system according to Clause 42, further comprising delivering the cardiac therapy by the modified vector including the at least two of the plurality of electrodes through a therapy delivery circuitry of the medical device system.

[0167] Clause 44. The medical device system according to Clause 42 or 43, wherein the medical device system includes a medical electrical lead, the medical electrical lead comprising a proximal end coupled to an implantable medical device and a distal portion comprising at least two of the plurality of electrodes, the distal portion being substantially implanted within the anterior mediastinum of the patient.

[0168] Clause 45. The medical device system according to Clause 44, wherein the implantable medical device includes an implantable cardioverter-defibrillator, and the plurality of electrodes includes a plurality of electrodes for delivering anti-tachyarrhythmia shock therapy, wherein the cardiac therapy includes the anti-tachyarrhythmia shock therapy, and wherein controlling the medical device system to deliver cardiac therapy via the modified vector including at least two of the plurality of electrodes includes controlling the medical device system to deliver the anti-tachyarrhythmia shock therapy.

[0169] Clause 46. The medical device system according to Clause 44, wherein the plurality of electrodes includes a plurality of electrodes for delivering cardiac pacing, wherein the cardiac therapy includes antiarrhythmic pacing, and wherein controlling the medical device system to deliver cardiac therapy via the modified vector including at least two of the plurality of electrodes includes controlling the medical device system to deliver the antiarrhythmic pacing.

[0170] Clause 47. The medical device system according to any one of Clauses 42 to 46, wherein the plurality of cardiac positions includes multiple postures.

[0171] Clause 48. The medical device system according to any one of Clauses 42 to 47, wherein determining the current cardiac position state of the patient includes determining at least one of the respiratory phase, respiratory rate, or respiratory depth of the patient.

[0172] Clause 49. The medical device system according to any one of Clauses 42 to 47, wherein modifying the vector including at least two of the plurality of electrodes based on the determined cardiac position state includes removing one of the at least two of the plurality of electrodes from the vector.

[0173] Clause 50. The medical device system according to Clause 49, wherein removing one of the at least two of the plurality of electrodes from the vector includes removing the uppermost one of the at least two of the plurality of electrodes.

[0174] Clause 51. The medical device system according to Clause 50, wherein determining the cardiac position state of the patient includes at least one of the following: determining that the patient is in an upright position; or determining that the respiratory state of the patient includes at least one of an inspiration phase, a respiratory depth that meets a respiratory depth threshold, or a respiratory rate that meets a respiratory rate threshold.

[0175] Clause 52. The medical device system according to any one of Clauses 42 to 51, further comprising a memory, wherein the processing circuitry is further configured to: store in the memory a respective value for each cardiac therapy parameter of a plurality of cardiac therapy parameters, and a respective modification associated with each cardiac position state of a plurality of cardiac position states for at least one of the cardiac therapy parameters; and modify the at least one cardiac therapy parameter value according to the modification associated with the cardiac position state of the patient, wherein the processing circuitry is configured to control the delivery of the cardiac therapy by the implantable medical device by at least controlling the delivery of the cardiac therapy according to the modified at least one cardiac therapy parameter value, to deliver the cardiac therapy by the modified vector including at least two of the plurality of electrodes.

[0176] Clause 53. The medical device system according to Clause 52, wherein the processing circuitry is configured to modify the at least one cardiac therapy parameter value by at least modifying a tachyarrhythmia detection parameter.

[0177] Clause 54. The medical device system according to Clause 53, wherein the processing circuitry is configured to modify the tachyarrhythmia detection parameter by at least modifying an electrocardiogram sensing amplitude threshold.

[0178] Clause 55. The medical device system according to Clause 52, wherein the processing circuitry is configured to modify the at least one cardiac therapy parameter value by at least modifying an antitachyarrhythmia shock magnitude.

[0179] Clause 56. The medical device system according to Clause 52, wherein the processing circuitry is configured to modify the at least one cardiac therapy parameter value by at least modifying an antitachyarrhythmia pacing parameter.

[0180] Clause 57. A method comprising any method described herein or any combination of the methods described herein.

[0181] Clause 58. A method comprising any combination of the methods according to Clauses 1 to 13 and 27 to 41.

[0182] Clause 59. A system comprising means for performing the method according to any one of Clauses 1 to 13, 27 to 41, 57 or 58.

[0183] Clause 60. A non-transitory computer-readable storage medium comprising instructions stored thereon which, when executed by a processing circuitry, cause the processing circuitry to perform the method according to any one of Clauses 1 to 13, 27 to 41, 57 or 58.

Claims

1. A medical device system, comprising: a plurality of electrodes; a memory configured to store a respective value for each of a plurality of parameters for at least one of anti-tachyarrhythmia shock therapy or cardiac sensing, and to store a respective modification for at least one of the plurality of parameters associated with each of a plurality of cardiac position states, wherein the stored modifications include a first modification of at least one parameter of the anti-tachyarrhythmia shock therapy parameters for a first cardiac position state, and a second modification of at least one parameter of the anti-tachyarrhythmia shock therapy parameters for a second cardiac position state, wherein the second cardiac position state is different from the first cardiac position state, and the second modification is different from the first modification; and a processing circuitry configured to: determine a current cardiac position state of a patient; determine that the current cardiac position state of the patient is the first cardiac position state; modify a value of at least one of the anti-tachyarrhythmia shock therapy parameters based at least in part on a determination that the current cardiac position state is the first cardiac position state, according to the modification associated with the first cardiac position state stored in the memory, wherein the processing circuitry is configured to modify the value of at least one of the anti-tachyarrhythmia shock therapy parameters by modifying an anti-tachyarrhythmia shock magnitude; control delivery of anti-tachyarrhythmia shock therapy via the plurality of electrodes according to the modified value of at least one of the anti-tachyarrhythmia shock therapy parameters associated with the first cardiac position state.

2. The medical device system according to claim 1, wherein The processing circuitry is further configured for: determine that the current cardiac position state of the patient is one of the plurality of cardiac position states; modify the value of at least one parameter according to the modification associated with the current cardiac position state, wherein the processing circuitry is configured to modify the value of at least one parameter by at least modifying a tachyarrhythmia detection parameter, a cardiac electrogram sensing amplitude threshold, or a cardiac pacing magnitude; and and control at least one of delivery of the anti-tachyarrhythmia shock therapy or the cardiac sensing via the plurality of electrodes according to the modified value of at least one parameter.

3. The medical device system according to any one of claims 1 or 2, further comprising: an implantable cardioverter defibrillator; and a medical electrical lead including a proximal end coupled to the implantable cardioverter defibrillator and a distal portion including at least one of the plurality of electrodes, the distal portion being configured for substantially implanting into the anterior mediastinum of the patient.

4. The medical device system according to any one of claims 1 to 2, wherein the plurality of cardiac position states include a plurality of postures.

5. The medical device system according to any one of claims 1 to 2, wherein the processing circuitry is configured to determine the current cardiac position state of the patient by at least determining at least one of a respiratory period, a respiratory rate, or a respiratory depth of the patient.

6. The medical device system according to claim 1, wherein the processing circuitry is configured to modify the tachyarrhythmia detection parameter by at least modifying an electrocardiogram sensing amplitude threshold.

7. The medical device system according to any one of claims 1 to 2, wherein the plurality of parameters includes a sensing vector and a shock vector, the sensing vector includes at least two of the plurality of electrodes, the shock vector includes at least two of the plurality of electrodes, and wherein the processing circuitry is configured to modify the parameter value by at least modifying at least one of the sensing vector or the shock vector.

8. The medical device system according to claim 7, wherein the processing circuitry is configured to modify at least one of the sensing vector or the shock vector by at least removing at least one of the at least two electrodes from the sensing vector or the shock vector.

9. The medical device system according to claim 8, wherein the processing circuitry is configured to remove at least one of the at least two electrodes by at least removing the uppermost one of the at least two electrodes of the plurality of electrodes.

10. The medical device system according to claim 9, wherein the at least two electrodes of the plurality of electrodes are located in a distal portion of a medical electrical lead, and wherein the processing circuitry is configured to remove the uppermost one of the at least two electrodes of the plurality of electrodes by at least removing the most distal one of the at least two electrodes of the plurality of electrodes.

11. The medical device system according to claim 10, wherein the processing circuitry is configured to determine the cardiac position state of the patient by at least one of: determining that the patient is in an upright position; or determining that the respiratory state of the patient includes at least one of an inspiration phase, a respiratory depth that meets a respiratory depth threshold, or a respiratory rate that meets a respiratory rate threshold.

12. A medical device system, comprising: a plurality of electrodes; a device for storing a respective value of each parameter of a plurality of parameters for at least one of anti-tachyarrhythmia shock therapy or cardiac sensing, and a respective modification for at least one of the plurality of parameters associated with each cardiac position state of a plurality of cardiac position states, wherein the stored modifications include a first modification of at least one parameter of the anti-tachyarrhythmia shock therapy parameters for a first cardiac position state, and a second modification of at least one parameter of the anti-tachyarrhythmia shock therapy parameters for a second cardiac position state, wherein the second cardiac position state is different from the first cardiac position state, and the second modification is different from the first modification; Apparatus for determining a current cardiac position state of a patient; Apparatus for determining that the current cardiac position state of the patient is the first cardiac position state; Apparatus for modifying at least one anti-tachyarrhythmia shock therapy parameter value based at least in part on a determination that the current cardiac position state is the first cardiac position state, according to a modification associated with the first cardiac position state stored in the memory, wherein the apparatus modifies the at least one anti-tachyarrhythmia shock therapy parameter value by modifying an anti-tachyarrhythmia shock magnitude value; and Apparatus for controlling delivery of anti-tachyarrhythmia shock therapy via the plurality of electrodes according to the modified at least one anti-tachyarrhythmia shock therapy parameter value associated with the first cardiac position state.

13. The medical device system according to claim 12, further comprising: Apparatus for determining that the current cardiac position state of the patient is one of the plurality of cardiac position states; Apparatus for modifying the at least parameter value according to a modification associated with the current cardiac position state, wherein the at least one parameter value is modified by at least modifying a tachyarrhythmia detection parameter, an electrocardiogram sensing amplitude threshold, or a cardiac pacing magnitude value; And Apparatus for controlling at least one of delivery of the anti-tachyarrhythmia shock therapy or cardiac sensing according to the modified at least one parameter value.

14. A medical device system for controlling electrocardiogram sensing or delivery of cardiac therapy, the system comprising: A plurality of electrodes; And A processing circuitry configured to: Determine that a current cardiac position state of a patient is a first cardiac position state and not a second cardiac position state, wherein determining that the current cardiac position state is the first cardiac position state and not the second cardiac position state includes determining at least one of a respiratory phase, a respiratory rate, or a respiratory depth of the patient; Modify a vector including at least two of the plurality of electrodes based at least in part on the determined at least one of the respiratory phase, the respiratory rate, or the respiratory depth of the patient, based on the determined current cardiac position state being the first cardiac position state; and Control the medical device system to deliver anti-tachyarrhythmia shock therapy via the modified vector including the at least two of the plurality of electrodes.

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