Adjusting programming settings during atrial fibrillation

Abstract

A medical device includes sensing circuitry configured to sense a cardiac electrogram signal via one or more electrodes coupled to the medical device; and processing circuitry configured to: based on the cardiac electrogram signal, determine a patient is experiencing an supraventricular tachycardia (SVT) episode; and based on the determination, adjust one or more sensing parameters of sensing the cardiac electrogram by the sensing circuitry, wherein the one or more sensing parameters include one or more of a ventricular blanking period or a ventricular sensitivity threshold, wherein to adjust the one or more sensing parameters, the processing circuitry is configured to adjust one or more of: the ventricular blanking period from a first period to a second period, the second period being longer than the first period; or the ventricular sensitivity threshold from a first threshold to a second threshold, the second threshold being higher than the first threshold.

Description

Atty Ref. No. A0012169W001ADJUSTING PROGRAMMING SETTINGS DURING ATRIAL FIBRILLATION

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 680,335, filed August 7, 2024, the entire content of which is incorporated herein by reference.FIELD

[0002] This disclosure generally relates to medical devices and, more particularly, to medical devices that monitor physiological parameters of patients.BACKGROUND

[0003] Some types of implantable medical devices, such as cardiac pacemakers or implantable cardioverter defibrillators, provide therapeutic electrical signals to a heart of a patient, such as bradycardia pacing, cardiac resynchronization therapy (CRT), antitachycardia pacing (ATP), and cardioversion / defibrillation shocks. The therapeutic electrical signals may be delivered to the heart in the form of pulses or shocks for pacing, cardioversion, or defibrillation. In some cases, an implantable medical device may sense intrinsic depolarizations of the heart and control the delivery of therapeutic signals to the heart based on the sensing.

[0004] CRT is one type of electrical stimulation therapy delivered by an implantable medical device. CRT may help enhance cardiac output by resynchronizing the electromechanical activity of the ventricles of the heart. Ventricular desynchrony may occur in patients that suffer from congestive heart failure (CHF). CRT includes delivering pacing stimuli to both ventricles (sometimes referred to as biventricular pacing), or to one ventricle (e.g., fusion pacing, such as left-ventricular pacing) with the intended result of a substantially simultaneous mechanical contraction and ejection of blood from the ventricles. A CRT device may deliver pacing in the right ventricle (RV) and / or the left ventricle (LV) to restore ventricular synchrony.Atly Ref. No. A0012169W001SUMMARY

[0005] In general, this disclosure describes techniques for adjusting one or more sensing parameters of an implantable medical device (IMD), e.g., a cardiac resynchronization therapy (CRT) device, based on a sensed physiological signal, e.g., a cardiac electrogram (EGM) signal. In some examples, the techniques include determining whether a patient is experiencing supraventricular tachycardia (SVT), such as atrial fibrillation (AF) or atrial flutter (AFL), based on the cardiac EGM, and based on the determination that the patient is experiencing SVT, adjusting the one or more sensing parameters, e.g., a ventricular sensitivity or a ventricular blanking period.

[0006] Many current CRT devices may not adjust sensing parameters based on whether the patient is experiencing SVT. During SVT episodes, cardiac EGMs are more likely to include oversensed waveforms, e.g., oversensed P-waves and / or T-waves. These P-waves and / or T-waves may in some examples be mistaken for R-waves, which may lead the CRT device to withhold ventricular pacing, e.g., withholding the therapeutic synchronization of CRT. By adjusting sensing parameters based on whether the patient is experiencing SVT, the techniques of this disclosure may prevent P-waves and T-waves from being mistaken for R-waves, which may improve patient outcomes.

[0007] In some examples, the techniques of this disclosure may include determining whether the SVT episode is an AF episode or an AFL episode. Based on the determination, a system including a pacing device, e.g., a CRT device, may make AFL episode-specific adjustments to the one or more sensing parameters, which may further improve patient outcomes.

[0008] In some examples, adjusting the one or more sensing parameters includes adjusting one or more of a ventricular sensitivity (V-sensitivity) threshold or a ventricular blanking period. In some examples, adjusting the V-sensitivity threshold includes adjusting the V-sensitivity threshold from a first value to a second, higher value for a period of time corresponding to the SVT episode. In some examples, adjusting the ventricular blanking period includes adjusting the ventricular blanking period from a first value to a second, higher value for a period of time corresponding to the SVT episode. Increasing the V-sensitivity threshold and / or the ventricular blanking period for a period of time corresponding to the SVT episode and switching back to the lower V-sensitivityAtly Ref. No. A0012169W001 threshold and / or ventricular blanking period may prevent oversensing during SVT episodes and may maintain sensitivity while the patient is not experiencing SVT.

[0009] In one example, a medical device comprises: sensing circuitry configured to sense a cardiac electrogram (EGM) signal of a patient via one or more electrodes coupled to the medical device; and processing circuitry configured to: based on the cardiac EGM signal, determine the patient is experiencing an SVT episode; and based on the determination that the patient is experiencing the SVT episode, adjust one or more sensing parameters of sensing the cardiac EGM by the sensing circuitry, wherein the one or more sensing parameters include one or more of a ventricular blanking period or a ventricular sensitivity threshold, wherein to adjust the one or more sensing parameters, the processing circuitry is configured to adjust one or more of: the ventricular blanking period from a first period to a second period, wherein the second period is longer than the first period; or the ventricular sensitivity threshold from a first threshold to a second threshold, wherein the second threshold is higher than the first threshold.

[0010] In another example, a method comprises: sensing, by sensing circuitry of a medical device, a cardiac EGM signal of a patient via one or more electrodes coupled to the medical device; determining, by processing circuitry of the medical device and based on the cardiac EGM signal, the patient is experiencing an SVT episode; and adjusting, by the processing circuity and based on the determination that the patient is experiencing the SVT episode, one or more sensing parameters of sensing the cardiac EGM by the sensing circuitry, wherein the one or more sensing parameters include one or more of a ventricular blanking period or a ventricular sensitivity threshold, wherein to adjust the one or more sensing parameters, the processing circuitry is configured to adjust one or more of: the ventricular blanking period from a first period to a second period, wherein the second period is longer than the first period; or the ventricular sensitivity threshold from a first threshold to a second threshold, wherein the second threshold is higher than the first threshold.

[0011] In another example, a non-transitory computer-readable medium stores instructions that when executed cause processing circuitry to: based on a cardiac EGM signal sensed via one or more electrodes coupled to a medical device, determine a patient is experiencing an SVT episode; and based on the determination that the patient is experiencing the SVT episode, adjust one or more sensing parameters of sensing theAtly Ref. No. A0012169W001 cardiac EGM by the sensing circuitry, wherein the one or more sensing parameters include one or more of a ventricular blanking period or a ventricular sensitivity threshold, wherein to adjust the one or more sensing parameters, the processing circuitry is configured to adjust one or more of: the ventricular blanking period from a first period to a second period, wherein the second period is longer than the first period; or the ventricular sensitivity threshold from a first threshold to a second threshold, wherein the second threshold is higher than the first threshold.

[0012] This summary is intended to provide an overview of the subject matter described in this disclosure. It is not intended to provide an exclusive or exhaustive explanation of the apparatus and methods described in detail within the accompanying drawings and description below. Further details of one or more examples are set forth in the accompanying drawings and the description below.BRIEF DESCRIPTION OF DRAWINGS

[0013] FIG. l is a conceptual diagram illustrating an example system configured to deliver cardiac pacing, the system including an implantable medical device (IMD) coupled to implantable medical leads, in accordance with one or more techniques of this disclosure.

[0014] FIG. 2 is a conceptual drawing illustrating the example IMD and leads of FIG. 1 in conjunction with a heart, in accordance with one or more techniques of this disclosure.

[0015] FIG. 3 is a functional block diagram illustrating an example configuration of the IMD of FIG. 1, in accordance with one or more techniques of this disclosure.

[0016] FIG. 4 is a functional block diagram illustrating an example configuration of the external device of FIG. 1, in accordance with one or more techniques of this disclosure.

[0017] FIG. 5 is a block diagram illustrating an example system configured to adjust one or more sensing parameters based on a determination that a patient is experiencing an supraventricular tachycardia (SVT) episode, in accordance with one or more techniques of this disclosure.Aty Ref. No. A0012169W001

[0018] FIG. 6 is a flow diagram illustrating an example operation for determining to adjust one or more sensing parameters, in accordance with one or more techniques of this disclosure.

[0019] FIG. 7 is a flow diagram illustrating an example operation for determining whether to adjust one or more sensing parameters based on a medical device configuration, in accordance with one or more techniques in this disclosure.

[0020] FIG. 8 is a flow diagram illustrating an example operation for determining whether to adjust sensing parameters based on whether the SVT episode is an atrial flutter (AFL) episode, in accordance with one or more techniques of this disclosure.

[0021] FIG. 9 is a flow diagram illustrating an example operation for determining when to switch between first and second sensing parameters based on whether the patient is experiencing the SVT episode, in accordance with one or more techniques of this disclosure.

[0022] FIG. 10 is a flow diagram illustrating an example operation for determining when to switch between first and second sensing parameters based on whether the patient is experiencing the SVT episode after a waiting period, in accordance with one or more techniques of this disclosure.

[0023] FIG. 11 is a flow diagram illustrating an example operation for determining whether to adjust a sensing parameter based on a patient heart rate (HR), in accordance with one or more techniques of this disclosure.

[0024] FIG. 12 is a flow diagram illustrating an example operation for determining to adjust a ventricular sensitivity threshold based on a noise level amplitude, in accordance with one or more techniques of this disclosure.

[0025] FIG. 13 is a flow diagram illustrating an example operation for setting the ventricular sensitivity threshold to a representative noise level amplitude, in accordance with one or more techniques of this disclosure.

[0026] FIG. 14 is a flow diagram illustrating an example operation for adjusting the ventricular sensitivity threshold based on a risk of P-wave oversensing and / or T-wave oversensing, in accordance with one or more techniques of this disclosure.

[0027] Like reference characters refer to like elements throughout the figures and description.Atty Ref. No. A0012169W001DETAILED DESCRIPTION

[0028] A variety of types of implantable and external devices are configured to monitor health based on sensed physiological signals. External devices that may be used to non-invasively sense and monitor physiological signals include wearable devices with electrodes configured to contact the skin of the patient, such as patches, watches, rings, necklaces, hearing aids, a wearable cardiac monitor or automated external defibrillator (AED), clothing, car seats, or bed linens. Such external devices may facilitate relatively longer-term monitoring of patient health during normal daily activities.

[0029] Implantable medical devices (IMDs) also sense and monitor physiological signals and detect and, in some examples, deliver therapy for, health events such as episodes of arrhythmia, cardiac arrest, myocardial infarction, stroke, and seizure. Example IMDs include cardiac resynchronization therapy (CRT) devices, which may be coupled to intravascular or extravascular leads, as well as pacemakers with housings configured for implantation within the heart, which may be leadless, such as the Micra™ leadless pacing device of Medtronic, Inc. CRT devices provide pacing pulses to patients based on monitored physiological signals.

[0030] A CRT device may deliver CRT pacing based on a cardiac EGM signal. Inaccurate sensing of the cardiac EGM can lead to the CRT device withholding ventricular pacing, which can lead to negative patient outcomes. Cardiac EGM waveforms associated with supraventricular tachycardiac (SVT) episodes, e.g., AF episodes, can be susceptible to oversensing, e.g., P-wave oversensing (PWOS) or T-wave oversensing (TWOS). In some examples, when PWOS occurs in the cardiac EGM signal, the CRT device may withhold ventricular pacing due to mistaking the oversensed P-waves as indicators of ventricular activity. When a patient is not experiencing SVT, the CRT device may correctly apply markers to R-waves. During SVT episodes, the CRT device may incorrectly apply R-wave markers to oversensed P-waves and / or T-waves. During oversensing, P-waves and T-waves may have signal amplitude in the frequency range on the cardiac EGM that exceeds a ventricular sensitivity (V-sensitivity) threshold, which may cause the system to withhold ventricular pacing. By adjusting sensing parameters based on whether the patient is experiencing SVT, the techniques of this disclosure may prevent P-waves and T-waves from being mistaken for R-waves.Atly Ref. No. A0012169W001

[0031] FIG. 1 is a conceptual diagram illustrating an example system 10 configured to deliver cardiac pacing, system 10 including an implantable medical device (IMD) coupled to implantable medical leads, in accordance with one or more techniques of this disclosure. In the example of FIG. 1, system 10 includes an implantable medical device (IMD) 16, which is coupled to leads 18, 20, and 22, and an external device 24. IMD 16 may be, for example, an implantable pacemaker, cardioverter, and / or defibrillator that provides electrical signals to heart 12 via electrodes coupled to one or more of leads 18, 20, and 22. Patient 14 is ordinarily, but not necessarily, a human patient.

[0032] In the example of FIG. 1, leads 18, 20, 22 extend into the heart 12 of patient 14 to sense electrical activity of heart 12, e.g., one or more cardiac EGM signals, and / or deliver electrical stimulation to heart 12.

[0033] In the example shown in FIG. 1, right ventricular (RV) lead 18 extends through one or more veins (not shown), the superior vena cava (not shown), and right atrium 26, and into right ventricle 28. Left ventricular (LV) coronary sinus lead 20 extends through one or more veins, the vena cava, right atrium 26, and into the coronary sinus 30 to a region adjacent to the free wall of left ventricle 32 of heart 12. Right atrial (RA) lead 22 extends through one or more veins and the vena cava, and into the right atrium 26 of heart 12.

[0034] In some examples, lead 18 may comprise an integrated bipolar sensing lead, and lead 20 may be configured to delivery pacing therapy. IMD 16 may sense, via lead 18, the cardiac EGM using first sensing parameters during normal sinus rhythm and may sense the cardiac EGM using second sensing parameters different from the first sensing parameters during periods of time corresponding to SVT episodes. In some examples, the sensing parameters to be adjusted include a ventricular sensitivity (V-sensitivity) threshold and / or a ventricular blanking period. In some examples, the sensing parameters additionally or alternatively include one or more of an auto-adjusting decay time constant, an auto-adjusting boost, a number of intervals to detect ventricular fibrillation (VFNID), a number of intervals to detect ventricular tachycardia (VTNID), an AF rejection rule, or a P-wave rejection rule.

[0035] In some examples, in addition or alternatively to adjusting the sensing parameters based on a determination that patient 14 is experiencing SVT, IMD 16 may determine to adjust the one or more sensing parameters based on a patient heart rate (HR),Atly Ref. No. A0012169W001 a patient HR variation (HRV), noise in the cardiac EGM, a timing interval between an atrial sense event and a ventricular sense event, variation in one or more R-waves in the cardiac EGM, and / or PWOS in the cardiac EGM.

[0036] The illustrated number and positions of leads 18, 20, and 22 are examples. In other examples, IMD 16 may be coupled to one, two, or more than three leads that extend to a variety of positions. In some examples, system 10 may additionally or alternatively include one or more leads or lead segments (not shown in FIG. 1) that deploy one or more electrodes within the vena cava, or other veins. Furthermore, in some examples, system 10 may additionally or alternatively include extravascular leads with electrodes implanted outside of heart 12, instead of or in addition to transvenous, intracardiac leads 18, 20 and 22. Such leads may be used for one or more of cardiac sensing, pacing, or cardioversion / defibrillation. Additionally, in some examples, system 10 may include one or more leadless cardiac pacing devices, such as the Micra™ pacemakers commercially available from Medtronic, Inc., instead of or in addition to IMD 16. One or more leadless pacemakers may be configured to deliver cardiac pacing in the manner described herein with respect to IMD 16. Furthermore, an external medical device may be configured to deliver cardiac pacing in the manner described herein with respect to IMD 16. In some examples, system 10 may additionally or alternatively include one or more implantable or external monitoring devices that monitor patient parameters but do not provide therapy, such as a Reveal LINQ™ insertable cardiac monitor, commercially available from Medtronic, Inc.

[0037] IMD 16 may sense electrical signals attendant to the depolarization and repolarization of heart 12 via electrodes (not shown in FIG. 1) coupled to at least one of the leads 18, 20, 22. In some examples, IMD 16 provides pacing pulses to heart 12 based on the electrical signals sensed within heart 12. The configurations of electrodes used by IMD 16 for sensing and pacing may be unipolar, bipolar, or integrated bipolar. In some examples, IMD 16 may deliver cardiac pacing to provide cardiac resynchronization therapy (CRT). In some examples, IMD 16 may additionally or alternatively be configured to provide conduction system pacing, which may provide a more physiologic activation of heart 12 than conventional pacing. In such examples, leads 18, 20, 22 may be configured / positioned such that their electrode(s) access (are capable of stimulating) the heart’s conduction system, e.g., the His bundle, left bundle branch, or right bundle branch.Atty Ref. No. A0012169W001

[0038] IMD 16 may detect arrhythmia of heart 12, such as tachycardia or fibrillation of the atria 26 and 36 and / or ventricles 28 and 32, and may also provide defibrillation therapy and / or cardioversion therapy via electrodes located on at least one of the leads 18, 20, 22. In some examples, IMD 16 may be programmed to deliver a progression of therapies, e.g., pulses with increasing energy levels, until a fibrillation of heart 12 is stopped. IMD 16 may detect fibrillation employing one or more fibrillation detection techniques known in the art.

[0039] IMD 16 may utilize two of any electrodes carried on leads 18, 20, 22 to sense EGM signals. In some examples, IMD 16 may also use a housing electrode of IMD 16 (not shown) to sense cardiac EGM signals and monitor cardiac activity. These cardiac EGM signals may be used to monitor heart 12 for potential arrhythmias, e.g., atrial fibrillation, and other disorders for therapy. IMD 16 may additionally monitor heart rate HR, HRV, indicators of blood flow, or other indicators of the ability of heart 12 to pump blood or the progression of heart failure (HF) and / or another disease state, e.g., high blood pressure, based on the EGM signal or another sensed signal.

[0040] IMD 16 may communicate with external device 24. In some examples, external device 24 comprises a handheld computing device, computer workstation, or networked computing device. External device 24 may be configured to retrieve data from IMD 16, e.g., for presentation to a clinician or other user, such as sensed parameter data of patient 14 and data regarding the operation of IMD 16. In some examples, external device 24 may provide the retrieved data to a cloud computing system, such as the CareLink™ system available from Medtronic, Inc., which may analyze the data and provide reports of the analysis and / or the data to clinicians or other users. In some examples, a clinician or other user may also interact with external device 24 to program IMD 16, e.g., select values for operational parameters of IMD 16. Although the user is typically a clinician, the user may be patient 14 in some examples.

[0041] In some examples, IMD 16, external device 24, or a cloud computing system may determine whether a patient is experiencing SVT and / or other patient state information based on physiological data, e.g., cardiac EGM data, collected by IMD 16. IMD 16 and external device 24 may communicate via wireless communication using any techniques known in the art. Examples of communication techniques may include, for example, radiofrequency (RF) telemetry or communication according to a Bluetooth®Atly Ref. No. A0012169W001 protocol, but other communication techniques such as magnetic coupling are also contemplated.

[0042] IMD 16 is an example of a device configured to deliver cardiac pacing pulses to a heart of a patient via a plurality of electrodes, sense a cardiac EGM of the patient, determine whether the patient is experiencing SVT, and adjust one or more sensing parameters based on the determination.

[0043] FIG. 2 is a conceptual drawing illustrating IMD 16 and leads 18, 20, and 22 of system 10 in greater detail, in accordance with one or more techniques of this disclosure. As shown in FIG. 2, IMD 16 is coupled to leads 18, 20, and 22. Leads 18, 20, 22 may be electrically coupled to therapy delivery circuitry and sensing circuitry of IMD 16 via connector block 34. In some examples, proximal ends of leads 18, 20, 22 may include electrical contacts that electrically couple to respective electrical contacts within connector block 34 of IMD 16. In addition, in some examples, leads 18, 20, 22 may be mechanically coupled to connector block 34 with the aid of set screws, connection pins, snap connectors, or another suitable mechanical coupling mechanism.

[0044] Each of the leads 18, 20, 22 includes an elongated insulative lead body, which may carry a number of concentric coiled conductors separated from one another by tubular insulative sheaths. Electrode 42 is located adjacent to a distal end of lead 18 in right ventricle 28. In addition, bipolar electrodes 44 and 46 are located adjacent to a distal end of lead 20 in coronary sinus 30 and bipolar electrodes 48 and 50 are located adjacent to a distal end of lead 22 in right atrium 26. In the illustrated example, there are no electrodes located in left atrium 33. However, other examples may include electrodes in left atrium 33. Furthermore, in examples in which IMD 16 is configured to deliver conduction system pacing, lead 18 may configured / positioned differently than illustrated in FIG. 2 so that electrode 42 may stimulate the conduction system, e.g., His bundle, left bundle branch, or right bundle branch. For example, electrode 42 may be positioned on or in the ventricular septum.

[0045] Electrodes 44 and 48 may take the form of ring electrodes, and electrodes 42, 46 and 50 may take the form of fixed or extendable helix tip electrodes mounted to insulative electrode heads 52, 54 and 56, respectively. In other examples, one or more of electrodes 42, 46 and 50 may take the form of small circular electrodes at the tip of a tined lead or other fixation element. Leads 18, 20, 22 also include elongated electrodes 62, 64,Aty Ref. No. A0012169W00166, respectively, which may take the form of a coil. Each of the electrodes 42, 44, 46, 48, 50, 62, 64 and 66 may be electrically coupled to a respective one of the coiled conductors within the lead body of its associated lead 18, 20, 22, and thereby coupled to respective ones of the electrical contacts on the proximal end of leads 18, 20 and 22.

[0046] In the example of FIG. 2 lead 18 is an integrated bipolar lead. In some examples, the techniques of this disclosure may include confirming a lead is integrated bipolar and / or that the lead is configured for integrated bipolar sensing before determining to adjust one or more sensing parameters based on a determination that the patient is experiencing SVT. In some examples, leads configured for integrated bipolar sensing or integrated bipolar sensing leads may be more sensitive to P-wave sensing than other lead configurations, e.g., true bipolar lead configurations. However, lead 18 may in some examples comprise a bipolar lead.

[0047] In some examples, as illustrated in FIG. 2, IMD 16 includes one or more housing electrodes, such as housing electrode 58, which may be formed integrally with an outer surface of hermetically-sealed housing 60 of IMD 16, or otherwise coupled to housing 60. In some examples, housing electrode 58 is defined by an uninsulated portion of an outward facing portion of housing 60 of IMD 16. Other division between insulated and uninsulated portions of housing 60 may be employed to define two or more housing electrodes. In some examples, housing electrode 58 comprises substantially all of housing 60. As described in further detail with reference to FIG. 3, housing 60 may enclose therapy delivery circuitry configured to generate therapeutic signals, such as cardiac pacing pulses and defibrillation shocks, as well as sensing circuitry for sensing the rhythm of heart 12 and other patient parameters.

[0048] IMD 16 may sense electrical signals attendant to the depolarization and repolarization of heart 12 via electrodes 42, 44, 46, 48, 50, 62, 64 and 66. The electrical signals are conducted to IMD 16 from the electrodes via the respective leads 18, 20, 22. IMD 16 may sense such electrical signals via any combination of electrodes 42, 44, 46, 48, 50, 62, 64 and 66, such as via electrodes 62 and 42 for integrated bipolar sensing. Furthermore, any of the electrodes 42, 44, 46, 48, 50, 62, 64 and 66 may be used for unipolar sensing in combination with housing electrode 58. The combination of electrodes used for sensing may be referred to as a sensing configuration or electrode vector.Atly Ref. No. A0012169W001

[0049] In some examples, IMD 16 delivers pacing pulses via bipolar combinations of electrodes 42, 44, 46, 48, and 50 to produce depolarization of cardiac tissue of heart 12. In some examples, IMD 16 delivers pacing pulses via any of electrodes 42, 44, 46, 48, 50, and 62 in combination with housing electrode 58 in a unipolar configuration.Furthermore, IMD 16 may deliver defibrillation pulses to heart 12 via any combination of elongated electrodes 62, 64, 66, and housing electrode 58. Electrodes 58, 62, 64, 66 may also be used to deliver cardioversion pulses to heart 12. Electrodes 62, 64, 66 may be fabricated from any suitable electrically conductive material, such as, but not limited to, platinum, platinum alloy or other materials known to be usable in implantable defibrillation electrodes. The combination of electrodes used for delivery of therapy or sensing, their associated conductors and connectors, and any tissue or fluid between the electrodes, may define an electrical path.

[0050] In some examples, IMD 16 may sense a cardiac EGM signal via coil electrode 62 and tip electrode 42 positioned in RV 28. Additionally, or alternatively, IMD 16 may sense the cardiac EGM signal via tip electrode 42 and housing electrode 58. Other cardiac EGM signal sensing configurations are also possible.

[0051] FIG. 3 is a functional block diagram illustrating an example configuration of IMD 16, in accordance with one or more techniques of this disclosure. In the illustrated example, IMD 16 includes processing circuitry 312, sensing circuitry 302, one or more sensor(s) 306, therapy delivery circuitry 304, communication circuitry 316, memory 314, and power source 310. Memory 314 includes computer-readable instructions that, when executed by processing circuitry 312, cause IMD 16 and processing circuitry 312 to perform various functions attributed to IMD 16 and processing circuitry 312 herein.Memory 314 may include any volatile, non-volatile, magnetic, optical, or electrical media, such as a random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, or any other digital or analog media.

[0052] Processing circuitry 312 may include any one or more of 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 examples, processing circuitry 312 may include multiple components, such as any combination of one or more microprocessors, one or more controllers, one orAtty Ref. No. A0012169W001 more DSPs, one or more ASICs, or one or more FPGAs, as well as other discrete or integrated logic circuitry. The functions attributed to processing circuitry 312 herein may be embodied as software, firmware, hardware or any combination thereof, e.g., may be embodied as software or firmware executed on processing circuitry.

[0053] Processing circuitry 312 controls therapy delivery circuitry 304 to deliver therapy to heart 12 according to therapy parameters and programs which may be stored in memory 314. Therapy delivery circuitry 304 is electrically coupled to electrodes 42, 44, 46, 48, 50, 58, 62, 64, and 66, e.g., via conductors of the respective lead 18, 20, 22, or, in the case of housing electrode 58, via an electrical conductor disposed within housing 60 of IMD 16. In the illustrated example, therapy delivery circuitry 304 is configured to generate and deliver electrical therapy to heart 12. For example, therapy delivery circuitry 304 may deliver defibrillation shocks to heart 12 via at least two electrodes 58, 62, 64, 66. Therapy delivery circuitry 304 may deliver pacing pulses via ring electrodes 44, 48 coupled to leads 20 and 22, respectively, and / or helical electrodes 42, 46, and 50 of leads 18, 20, and 22, respectively. In some examples, therapy delivery circuitry 304 delivers pacing, cardioversion, or defibrillation stimulation in the form of electrical pulses. In other examples, therapy delivery circuitry 304 may deliver one or more of these types of stimulation in the form of other signals, such as sine waves, square waves, or other substantially continuous time signals. Processing circuitry 312 may be configured to determine whether a patient is experiencing an SVT episode based on the cardiac EGM signal and / or another physiological signal.

[0054] Therapy delivery circuitry 304 includes circuitry, such as charge pumps, capacitors, current mirrors, or other signal generation circuitry for generating a pulse or other signal. Therapy delivery circuitry 304 may include a switch module, and processing circuitry 312 may use the switch module to select, e.g., via a data / address bus, which of the available electrodes are used to deliver antitachyarrhythmia shocks or pacing pulses. The switch module may include a switch array, switch matrix, multiplexer, or any other type of switching device suitable to selectively couple stimulation energy to selected electrodes.

[0055] Sensing circuitry 302 monitors signals from at least one of electrodes 42, 44, 46, 48, 50, 58, 62, 64 or 66, e.g., electrodes 42 and 62, in order to monitor cardiac EGM signals of heart 12 and / or other patient parameters. Memory 314 may store the cardiacAtly Ref. No. A0012169W001EGM signals. Sensing may be done to detect intrinsic cardiac depolarizations, to detect arrhythmias, to determine heart rates or heart rate variability, or to detect other electrical signals. Sensing circuitry 302 may include one or more filters, amplifiers, analog-to-digital converters, or other sensing circuitry.

[0056] Sensing circuitry 302 may also include a switch module to select which of the available electrodes are used to sense the heart activity, depending upon which electrode combination, or electrode vector, is used in the current sensing configuration. In some examples, processing circuitry 312 may select the electrodes that function as sense electrodes, i.e., select the sensing configuration, via the switch module within sensing circuitry 302. Sensing circuitry 302 may include one or more detection channels, each of which may be coupled to a selected electrode configuration for detection of cardiac signals via that electrode configuration. Some detection channels may be configured to detect cardiac events, such as P- or R-waves, and provide indications of the occurrences of such events to processing circuitry 312.

[0057] One or more sensor(s) 306 may include, as examples, one or more accelerometers, microphones, temperature sensors, or optical sensors that are configured to provide signals or data representing one or more patient parameters to processing circuitry 312 via sensing circuitry 302. In some examples, processing circuitry 312 may determine a patient state information, e.g., whether patient 14 is experiencing SVT, patient 14’s HR, patient 14’s HRV, or patient 14’s overall disease state, based on signals sensed via one or more sensor(s) 306 in addition to or instead of the cardiac EGM signal.

[0058] Processing circuitry 312 may implement programmable counters that control the basic time intervals associated with DDD, VVI, DVI, VDD, AAI, DDI, DDDR, VVIR, DVIR, VDDR, AAIR, DDIR, CRT, and other modes of pacing. Intervals defined by processing circuitry 312 may include atrial and ventricular pacing escape intervals, A-V intervals, V-V intervals, and refractory periods during which sensed P-waves and R-waves are ineffective to restart timing of the intervals. The durations of these intervals may be determined by processing circuitry 312 in response to stored data in memory 314.

[0059] In some examples, processing circuitry 312 may modify escape intervals based on a rate responsive pacing mode. Processing circuitry 312 may determine a sensor indicated pacing rate based on sensed parameters of patient 14, such as one or more of activity level or respiration rate, and thereby modify the escape interval and pacing rate toAtly Ref. No. A0012169W001 provide cardiac pacing that supports the activity of patient 14. In some examples, processing circuitry 312 may additionally modify the pacing mode based on a patient disease state or other patient data. In some examples, processing circuitry 312 may control IMD 16 to provide CRT by controlling delivery of pacing pulses to one or both of RV 28 and LV 32 based on atrioventricular timing and interventricular timing specified by one or more A-V intervals and V-V intervals.

[0060] Interval counters implemented by processing circuitry 312 may be reset upon sensing of R-waves and P-waves with detection channels of sensing circuitry 302. In examples in which IMD 16 provides pacing, therapy delivery circuitry 304 may include pacer output circuits that are coupled, e.g., selectively by a switching module, to any combination of electrodes 42, 44, 46, 48, 50, 58, 62, or 66 appropriate for delivery of integrated bipolar, bipolar, or unipolar pacing pulse to one of the chambers of heart 12. In such examples, processing circuitry 312 may reset the interval counters upon the generation of pacing pulses by therapy delivery circuitry 304, and thereby control the basic timing of cardiac pacing functions, including anti-tachyarrhythmia pacing.

[0061] The value of the count present in the interval counters when reset by sensed R-waves and P-waves may be used by processing circuitry 312 to measure the durations of R-R intervals, P-P intervals, P-R intervals and R-P intervals, which are measurements that may be stored in memory 314. Processing circuitry 312 may use the count in the interval counters to detect a tachyarrhythmia event, such as AF, atrial tachycardia (AT), ventricular fibrillation (VF), or ventricular tachycardia (VT). These intervals may also be used to detect the overall heart rate, ventricular contraction rate, and HRV. A portion of memory 314 may be configured as a plurality of recirculating buffers, capable of holding series of measured intervals, which may be analyzed by processing circuitry 312 in response to the occurrence of a pace or sense interrupt to determine whether the patient’s heart 12 is presently exhibiting atrial or ventricular tachyarrhythmia.

[0062] In some examples, processing circuitry 312 may determine that tachyarrhythmia has occurred by identification of shortened R-R (or P-P) interval lengths. Generally, processing circuitry 312 detects tachycardia when the interval length falls below 220 milliseconds (ms) and fibrillation when the interval length falls below 180 ms. These interval lengths are merely examples, and a user may define the interval lengths as desired, which may then be stored within memory 314. This interval length may need toAtly Ref. No. A0012169W001 be detected for a certain number of consecutive cycles, for a certain percentage of cycles within a running window, or a running average for a certain number of cardiac cycles, as examples.

[0063] In the event that processing circuitry 312 detects an atrial or ventricular tachyarrhythmia based on signals from sensing circuitry 302, and an anti-tachyarrhythmia pacing regimen is desired, timing intervals for controlling the generation of anti -tachyarrhythmia pacing therapies by therapy delivery circuitry 304 may be loaded by processing circuitry 312 to control the operation of the escape interval counters therein and to define refractory periods during which detection of R-waves and P-waves is ineffective to restart the escape interval counters for the an anti-tachyarrhythmia pacing. In the event that processing circuitry 312 detects an atrial or ventricular tachyarrhythmia based on signals from sensing circuitry 302, and a cardioversion or defibrillation shock is desired, processing circuitry 312 may control the amplitude, form and timing of the shock delivered by therapy delivery circuitry 304.

[0064] Communication circuitry 316 includes any suitable hardware, firmware, software or any combination thereof for communicating with another device, such as external device 24 (FIG. 1). Under the control of processing circuitry 312, communication circuitry 316 may communicate with external device 24 with the aid of an antenna, which may be internal and / or external.

[0065] Power source 310 is configured to delivery operating power to the components of IMD 16. Power source 310 may include a battery and a power generation circuitry to produce the operating power. In some examples, the battery is rechargeable to allow extended operation. In some examples, recharging is accomplished through proximal inductive interaction between an external charger and an inductive charging coil within IMD 16. Power source 310 may include any one or more of a plurality of different battery types, such as nickel cadmium batteries and lithium ion batteries. A non-rechargeable battery may be selected to last for several years, while a rechargeable battery may be inductively charged from an external device, e.g., on a daily or weekly basis.

[0066] FIG. 4 is a block diagram illustrating an example configuration of an external device 24 that operates in accordance with one or more techniques of this disclosure. External device 24 is configured to communicate with any IMD (e.g., IMD 16), in accordance with one or more techniques of this disclosure. In the example of FIG. 4,Atly Ref. No. A0012169W001 external device 24 includes processing circuitry 402, communication circuitry 406, user interface 404, power source 410, and memory 408.

[0067] Processing circuitry 402, in one example, may include one or more processors that are configured to implement functionality and / or process instructions for execution within external device 24. For example, processing circuitry 402 may be capable of processing instructions stored in memory 408. Processing circuitry 402 may include, for example, microprocessors, DSPs, ASICs, FPGAs, GPUs, TPUs, or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuitry. Accordingly, processing circuitry 402 may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions ascribed herein to processing circuitry 402.

[0068] Communication circuitry 406 may include any suitable hardware, firmware, software or any combination thereof for communicating with another device, such as IMD 16. Under the control of processing circuitry 402, communication circuitry 406 may receive downlink telemetry from, as well as send uplink telemetry to, IMD 16, or another device.

[0069] A user, such as a clinician or patient 14, may interact with external device 24 through user interface 404. User interface 404 includes a display (not shown), such as an LCD or LED display or other type of screen, with which processing circuitry 402 may present information related to IMD 16 (e.g., a detection of a cardiac episode). In addition, user interface 404 may include an input mechanism to receive input from the user. The input mechanisms may include, for example, any one or more of buttons, a keypad (e.g., an alphanumeric keypad), a peripheral pointing device, a touch screen, or another input mechanism that allows the user to navigate through user interfaces presented by processing circuitry 402 of external device 24 and provide input. In other examples, user interface 404 also includes audio circuitry for providing audible notifications, instructions or other sounds to patient 14, receiving voice commands from patient 14, or both. Memory 408 may include instructions for operating user interface 404 and for managing power source 410.

[0070] Power source 410 is configured to deliver operating power to the components of external device 24. Power source 410 may include a battery and a power generation circuit to produce the operating power. In some examples, the battery is rechargeable toAty Ref. No. A0012169W001 allow extended operation. Recharging may be accomplished by electrically coupling power source 410 to a cradle or plug that is connected to an alternating current (AC) outlet. In addition, recharging may be accomplished through proximal inductive interaction between an external charger and an inductive charging coil within external device 24. In other examples, traditional batteries (e.g., nickel cadmium or lithium ion batteries) may be used. In addition, external device 24 may be directly coupled to an alternating current outlet to operate.

[0071] Memory 408 may be configured to store information within external device 24 during operation. In some examples, memory 408 may be referred to as a storage device and include computer-readable instructions that, when executed by processing circuitry 402, cause external device 24 and processing circuitry 402 to perform various functions attributed to external device 24 and processing circuitry 402 herein. Memory 408 may include any volatile, non-volatile, magnetic, optical, or electrical media, such as RAM, DRAM, SRAM, magnetic discs, optical discs, flash memories, ROM, NVRAM, EPROM, EEPROM, flash memory, or any other digital media. Memory 408 may also store data generated by sensing circuitry 302 of IMD 16, such as signals corresponding to indications of detections.

[0072] FIG. 5 is a block diagram illustrating an example system 2 that includes an access point 502, a network 504, external computing devices, such as server 508, and one or more other computing devices 506A-506N, which may be coupled to IMD 16, and external device 24 via network 504, in accordance with one or more techniques described herein. IMD 16 may communicate with external device 24 via a first wireless connection and may communicate with an access point 502 via a second wireless connection. In the example of FIG. 5, access point 502, external device 24, server 508, and computing devices 506A-506N are interconnected and may communicate with each other through network 504.

[0073] Access point 502 may include a device that connects to network 504 via any of a variety of connections, such as telephone dial-up, digital subscriber line (DSL), or cable modem connections. In other examples, access point 502 may be coupled to network 504 through different forms of connections, including wired or wireless connections. In some examples, access point 502 may be a user device, such as a tablet or smartphone, that may be co-located with the patient. As discussed above, IMD 16 may be configured to transmitAtty Ref. No. A0012169W001 physiological data to external device 24. In addition, access point 502 may interrogate IMD 16, such as periodically or in response to a command from the patient or network 504, in order to retrieve patient data from IMD 16. Access point 502 may be communicate the retrieved data to server 508 via network 504.

[0074] In some cases, server 508 may be configured to provide a secure storage site for data that has been collected from IMD 16, and / or external device 24. In some cases, server 508 may assemble data for viewing by clinicians via computing devices 506A- 506N. One or more aspects of the illustrated system of FIG. 5 may be implemented with general network technology and functionality, which may be similar to that provided by the Medtronic CareLink™ Network developed by Medtronic, Inc.

[0075] Server 508 may include processing circuitry (not depicted). The processing circuitry of server 508 may include fixed function circuitry and / or programmable processing circuitry and may include any one or more of a microprocessor, a controller, digital signal processor (DSP), an application specific integrated circuit (ASIC), a field- programmable gate array (FPGA), graphics processing unit (GPU), tensor processing unit (TPU), or equivalent discrete or analog logic circuitry. In some examples, processing circuitry of server 508 may 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 FGPAs, one or more GPUs, one or more TPUs, as well as other discrete of integrated logic circuitry. The functions attributed to processing circuitry of server 508 may be embodied as software, firmware, hardware, or any combination thereof.

[0076] Server 508 may include storage device (not depicted). The storage device of server 508 includes computer-readable instructions that, when executed by processing circuitry of server 508, cause IMD 16 and processing circuitry of server 508 to perform various functions attributed to IMD 16 and processing circuitry of server 508 herein. The storage device of server 508 may include any volatile, non-volatile, magnetic, optical, or electrical media, such as random access memory (RAM), read only memory (ROM), nonvolatile RAM (NVRAM), electronically erasable programmable ROM (EEPROM), flash memory, or any other digital media.

[0077] In some examples, one or more of computing devices 506A-506N (collectively, “computing devices 506”), e.g., computing device 506A, may be a tablet or other smart device located with a clinician, by which the clinician may program, receiveAtty Ref. No. A0012169W001 alerts from, and / or interrogate IMD 16. For example, the clinician may access data corresponding to a cardiac EGM signal and any other types of signals collected by IMD 16, or SVT episode updates determined by IMD 16 based on such signals, through device 506A, such as when patient 14 is in between clinician visits. In some examples, the clinician may enter instructions for medical intervention for patient 14 into an application in computing device 506A, such as based on a status of a patient condition determined by IMD 16, external device 24, or the combination thereof, or based on other patient data known to the clinician. Computing device 506A may then transmit the instructions for updating programming of IMD 16 to another of computing devices 506, e.g., computing device 506B, located with patient 14 or a caregiver of patient 14 or to IMD 16. For example, such instructions may include instructions to update one or more of the sensing parameters, e.g., the V-sensitivity thresholds or the ventricular blanking periods, and / or update an operation for adjusting the sensing parameters when SVT is detected. For example, based on a frequency of SVT episodes in patient 14, the clinician may determine to update the operation for adjusting sensing parameters from adjusting the sensing parameters when an SVT episode is no longer detected, e.g., the operation described with respect to FIG. 9, to checking whether to adjust the sensing parameters when a threshold time has passed after detecting an SVT episode, e.g., the operation described with respect to FIG. 10. In this manner, the clinician may be able to update to sensing parameters between scheduled visits, which may help improve clinical outcomes for patient 14.

[0078] FIG. 6 is a flow diagram illustrating an example operation for determining to adjust one or more sensing parameters, in accordance with one or more techniques of this disclosure. Sensing circuitry 302 of IMD 16 senses a cardiac EGM signal of a patient, e.g., patient 14, via one or more electrodes, e.g., electrodes 42 and 62 of lead 18, coupled to a medical device, e.g., IMD 16 (602). Based on the cardiac EGM signal, processing circuitry of system 10, e.g., processing circuitry 312 of IMD 16, determines whether patient 14 is experiencing an SVT episode (604). If patient 14 is experiencing an SVT episode (“YES” of 604), processing circuitry adjusts one or more sensing parameters of sensing the cardiac EGM by sensing circuitry 302. Processing circuitry 312 may continue to sense the cardiac EGM using the adjusted parameters and continue to determine whether the patient is in SVT, e.g., using the cardiac EGM. Processing circuitry 312 may revert to the sensingAtty Ref. No. A0012169W001 parameter values prior to adjustment, e.g., when the processing circuitry determines that patient 14 is no longer in SVT or after a predetermined time period.

[0079] The one or more sensing parameters may include a ventricular blanking period and a V-sensitivity threshold. The ventricular blanking period is a period that occurs after a ventricular event (e.g., after the QRS complex) in which the system is configured to temporary disable or “blank” to prevent oversensing, e.g., TWOS. The V-sensitivity threshold is a threshold setting a minimum voltage value at which processing circuitry 312 determines a QRS complex is present in the signal. In some examples, adjusting the ventricular blanking period includes temporarily, e.g., during a period of time corresponding to the SVT episode, increasing the ventricular blanking period, e.g., from 120 milliseconds (ms) to 140 ms, and adjusting the V-sensitivity threshold includes temporarily increasing the V-sensitivity threshold, e.g., from 0.30 millivolts (mV) to 0.45 mV. In some examples, the ventricular blanking period may range from 120 ms to 150 ms. In some examples, the V-sensitivity threshold may range from 0.30 mV to 0.60 mV. The period of time corresponding to the SVT episode may be a duration of the SVT episode or may be a predetermined amount of time immediately following the identification of the SVT episode, e.g., 5 minutes.

[0080] In some examples, the one or more sensing parameters may additionally or alternatively include one or more of an auto-adjusting decay time constant, an autoadjusting boost, a VFNID, a VTNID, an AF rejection rule, or a P-wave rejection rule. The auto-adjusting decay time constant is a dynamically adjusting duration over which processing circuitry 312 of IMD 16 integrates or averages the sensed cardiac EGM signal, which can prevent noise from being misinterpreted in the signal. In some examples, when processing circuitry 312 determines the patient is experiencing SVT, e.g., AF, processing circuitry 312 may increase the decay time constant to prevent AF-related noise from being misinterpreted. Auto-adjusting boost may be a temporary boost in a threshold. In some examples, the temporary boost in threshold is coincident with an anticipated timing of a T- wave and may prevent TWOS. Conditions such as SVT can cause relatively high amplitude TWOS compared to TWOS during normal sinus rhythm. Processing circuitry 312 may adjust an auto-adjusting boost by increasing an amplitude to which the threshold temporarily increases, thereby preventing relatively high amplitude T-waves associated with SVT episodes from being oversensed. Processing circuitry 312 may increase aAtly Ref. No. A0012169W001VFNID value or a VTNID value. Processing circuitry 312 may adjust the AF rejection rule and / or P-wave rejection rule by increasing a sensitivity of the AF rejection rule and / or P- wave rejection rule when processing circuitry 312 determines patient 14 is experiencing an AF episode. If patient 14 is not experiencing AF (“NO” of 604), processing circuitry 312 determines to continue sensing the cardiac EGM signal to continue monitoring for AF (602).

[0081] In some examples, in addition to or instead of adjusting the one or more sensing parameters based on a determination that patient 14 is experiencing an AF episode, processing circuitry 312 may be configured to adjust one or more of the ventricular blanking period or the V-sensitivity threshold within a 150 millisecond (ms) window immediately following an atrial sense event and between 250 ms and 650 ms immediately following a ventricular sense event. As an example, instead of statically adjusting the one or more sensing parameters during the period of time corresponding to the AF episode, processing circuitry may determine to adjust the one or more sensing parameters only during periods in which P-wave oversensing and T-wave oversensing are relatively likely to occur, e.g., within 150 ms immediately following an atrial sense event and between 250 ms and 650 ms immediately following a ventricular sense event. In examples in which processing circuitry 312 adjusts the one or more of the ventricular blanking period or the V-sensitivity threshold within the 150 millisecond (ms) window immediately following the atrial sense event and between 250 ms and 650 ms immediately following the ventricular sense event instead of adjusting the one or more sensing parameters based on a determination that patient 14 is experiencing the AF episode, processing circuitry may adjust the ventricular blanking period or the V-sensitivity threshold during both AF episodes and during normal sinus rhythm.

[0082] FIG. 7 is a flow diagram illustrating an example operation for determining whether to adjust one or more sensing parameters based on a medical device configuration, in accordance with one or more techniques in this disclosure. In some examples, processing circuitry of system 10, e.g., processing circuitry 312 of IMD 16, may be configured to determine whether to adjust the one or more sensing parameters in response to determining patient 14 is experiencing SVT based on a configuration of the medical device. In some examples, prior to performing the example operation of FIG. 6, processing circuitry 312 performs the example operation of FIG. 7. Processing circuitryAtly Ref. No. A0012169W001312 determines a medical device configuration, e.g., a lead configuration, of IMD 16 (702). Processing circuitry 312 determines if the lead and / or the sensing vector is integrated bipolar, e.g., if the lead is a bipolar or unipolar lead but is also capable of integrated bipolar sensing (704). If the lead and / or the sensing vector is integrated bipolar (“YES” of 704), processing circuitry 312 determines to enable SVT detection-based sensing parameter adjustments (706). Processing circuitry 312 may subsequently perform the example operation of FIG. 6. If the lead and / or the sensing vector is not integrated bipolar (“NO” of 704), processing circuitry 312 determines not to enable SVT detectionbased sensing parameter adjustments (708).

[0083] In some examples, integrated bipolar sensing leads may be more susceptible to oversensing, e.g., PWOS and / or TWOS, than other lead configurations, such as true bipolar and unipolar sensing lead configurations. While oversensing is possible in other lead configurations, processing circuitry 312 may determine not to enable SVT -detection based sensing parameter adjustments in other lead configurations. In some examples, not enabling the SVT -detection based sensing parameter adjustments, in response to determining the lead and / or sensing vector is not integrated bipolar, may decrease a computational burden of IMD 16 and / or system 10, potentially improving longevity of system 10. Additionally, in other lead configurations, e.g., in true bipolar lead configurations, adjusting the one or more parameters to temporarily decrease sensitivity in response to detecting SVT with a true bipolar lead, may, in some examples, cause QRS complexes to go undetected, which could lead to false detection of bradyarrhythmia and unnecessary therapy administration or under-detection of tachyarrhythmia and missing needed therapy administration. While the techniques of this disclosure could lead to similar issues with integrated bipolar sensing lead configurations, the benefit associated with preventing therapy from being withheld may outweigh the potential for unnecessary therapy administration, making the techniques disclosed particularly suitable for systems with integrated bipolar sensing lead configurations.

[0084] FIG. 8 is a flow diagram illustrating an example operation for determining whether to adjust sensing parameters based on whether the SVT episode is an atrial flutter (AFL) episode, in accordance with one or more techniques of this disclosure. For the purposes of this disclosure, the term “SVT episode” is considered to generically describe AF and AFL episodes. In some examples, it may be desirable to differentiate between aAtty Ref. No. A0012169W001 first type of SVT episode, e.g., an AF episode, and an AFL episode. Processing circuitry of system 10, e.g., processing circuitry 312 of IMD 16, determines whether a patient, e.g., patient 14, is experiencing an SVT episode (802). Processing circuitry 312 determines whether the SVT episode is an AFL episode (804). In some examples, processing circuitry 312 determines patient 14 is experiencing an SVT episode and subsequently determines whether the SVT episode is an AFL episode, as described in FIG. 8. In other examples, at the time processing circuitry 312 determines patient 14 is experiencing the SVT episode, processing circuitry 312 determines the patient is experiencing the AFL episode. If patient 14 is experiencing an AFL episode (“YES” of 804), processing circuitry 312 determines to adjust one or more sensing parameters according to an AFL episode protocol (806). In some examples, due to the difference in morphology between AFL episodes and other SVT episodes, e.g., AF episodes, it may be desirable to adjust the one or more sensing parameters differently, e.g., to a different extent or for a different period of time, during AFL episodes and during AF episodes. If patient 14 is not experiencing AFL (“NO” of 804), processing circuitry 312 determines not to adjust the one or more sensing parameters according to the AFL episode protocol and instead adjusts the one or more parameters to another SVT episode protocol, e.g., an AF episode protocol (808).

[0085] FIG. 9 is a flow diagram illustrating an example operation for determining when to switch between first and second sensing parameters based on whether the patient is experiencing the SVT episode, in accordance with one or more techniques of this disclosure. The example operation of FIG. 9 may be a specific example of the example operation of FIG. 6. Sensing circuitry 302 of IMD 16 senses a cardiac EGM of the patient via one or more electrodes coupled to IMD 16, e.g., electrodes 42 and 62 of lead 18 of FIG. 2, using first sensing parameters (902). In some examples, lead 18 is an integrated bipolar lead. In some examples, the sensing vector is an integrated bipolar sensing vector.

[0086] Processing circuitry of system 10, e.g., processing circuitry 312, determines, based on the cardiac EGM signal, whether a patient, e.g., patient 14, is experiencing an SVT episode (904). If patient 14 is not experiencing an SVT episode (“NO” of 904), sensing circuitry 302 continues to sense the cardiac EGM signal using the first sensing parameters (902). Processing circuitry 312 continues to monitor for SVT episodes. If patient 14 is experiencing an SVT episode (“YES” of 904), processing circuitry 312 may optionally determine whether there are oversensed waveforms, e.g., oversensed P-wavesAtly Ref. No. A0012169W001 and / or oversensed T-waves, in the cardiac EGM signal (906). In some examples, the processing circuitry may not perform an oversensing check and may move from determining whether patient 14 is experiencing an SVT episode to sensing with second sensing parameters. If there is no oversensing (“NO” of 906), sensing circuity 302 continues to sense the cardiac EGM signal using the first sensing parameters (902).

[0087] If there are oversensed waveforms in the cardiac EGM signal (“YES” of 906), processing circuitry 312 determines to adjust the sensing parameters from the first sensing parameters to second sensing parameters (908). In some examples, the sensing parameters include a ventricular blanking period and a V-sensitivity threshold. In some examples, the first ventricular blanking period and the first V-sensitivity threshold are lower than the second ventricular blanking period and the second V-sensitivity threshold. For example, the first ventricular blanking period may be 120 ms, and the second ventricular blanking period may be 140 ms. The first V-sensitivity threshold may be 0.30 mV, and the second V-sensitivity threshold may be 0.45 mV.

[0088] In some examples, switching from the first sensing parameters to the second sensing parameters may additionally include adjusting one or more of an auto-adjusting decay time constant, an auto-adjusting boost, a VFNID, a VTNID, an AF rejection rule, or a P-wave rejection rule.

[0089] Processing circuitry 312 determines whether patient 14 is still experiencing the SVT episode (910). If patient 14 is no longer in SVT (“NO” of 910), processing circuitry 312 determines to switch back to sensing with the first sensing parameters (902). If patient 14 is still in SVT (“YES” of 910), processing circuitry 312 determines to continue to use the second sensing parameters (908). Processing circuitry 312 continues to check whether patient 14 is still in SVT until the SVT episode ends.

[0090] FIG. 10 is a flow diagram illustrating an example operation for determining when to switch between first and second sensing parameters based on whether the patient is experiencing the SVT episode after a waiting period, in accordance with one or more techniques of this disclosure. The example operation of FIG. 10 may be a specific example of the example operation of FIG. 6. Sensing circuitry 302 of IMD 16 senses a cardiac EGM of a patient, e.g., patient 14, via one or more electrodes coupled to IMD 16, e.g., electrodes 42 and 62 of lead 18 of FIG. 2, using first sensing parameters (1002). TheAtly Ref. No. A0012169W001 sensing vector may be an integrated bipolar sensing vector and / or the lead may be an integrated bipolar lead.

[0091] Processing circuitry of system 10, e.g., processing circuitry 312, determines, based on the cardiac EGM signal, whether a patient, e.g., patient 14, is experiencing an SVT episode (1004). If patient 14 is not experiencing an SVT episode (“NO” of 1004), sensing circuitry 302 continues to sense the cardiac EGM signal using the first sensing parameters (1002). Processing circuitry 312 continues to monitor for SVT episodes. If patient 14 is experiencing an SVT episode (“YES” of 1004), processing circuitry 312 may optionally determine whether there are oversensed waveforms, e.g., oversensed P-waves and / or oversensed T-waves, in the cardiac EGM signal (1006). In some examples, the processing circuitry may not perform an oversensing check and may move from determining whether patient 14 is experiencing an SVT episode to sensing with second sensing parameters. If there is no oversensing (“NO” of 1006), sensing circuity 302 continues to sense the cardiac EGM signal using the first sensing parameters (1002). If there are oversensed waveforms in the cardiac EGM signal (“YES” of 1006), processing circuitry 312 determines to adjust the sensing parameters from the first sensing parameters to second sensing parameters (1008).

[0092] In some examples, the sensing parameters include a ventricular blanking period and a V-sensitivity threshold. In some examples, the first ventricular blanking period and the first V-sensitivity threshold are lower than the second ventricular blanking period and the second V-sensitivity threshold. For example, the first ventricular blanking period may be 120 ms, and the second ventricular blanking period may be 140 ms. The first V- sensitivity threshold may be 0.30 mV, and the second V-sensitivity threshold may be 0.45 mV.

[0093] In some examples, switching from the first sensing parameters to the second sensing parameters may additionally include adjusting one or more of an auto-adjusting decay time constant, an auto-adjusting boost, a VFNID, a VTNID, an AF rejection rule, or a P-wave rejection rule.

[0094] Processing circuitry 312 continues to control sensing circuitry 302 to sense the cardiac EGM signal using the second sensing parameters for X minutes, e.g., 2 minutes, 3 minutes, or 5 minutes (1010). After X minutes, processing circuitry 312 controls sensing circuitry 302 to sense the cardiac EGM signal using the first sensing parameters (1012).Atly Ref. No. A0012169W001Processing circuitry 312 continues to control sensing circuitry 302 to sense the cardiac EGM using the first sensing parameters for Y minutes, e.g., 2 minutes (1014). After Y minutes, processing circuitry 312 determines whether the patient is still experiencing the SVT episode (1004).

[0095] In some examples, processing circuitry of system 10, e.g., processing circuitry 312 of IMD 16 or processing circuitry 402 of external device 24, and / or the clinician may determine whether to apply the example operation of FIG. 9 or the example operation of FIG. 10. In some examples, processing circuitry 312 / processing circuitry 402 and / or the clinician may determine to apply the example operation of FIG. 10 for patients who experience relatively frequent SVT and may determine to apply the example operation of FIG. 9 for patients who experience relatively infrequent SVT. Patients with relatively frequent SVT may experience longer and / or more frequent SVT episodes. In some examples, the first sensing parameters may be more sensitive than the second sensing parameters. Therefore, the first sensing parameters may be more sensitive to ventricular events in addition to being susceptible to oversensing. In some examples, the processing circuitry 312 and / or the clinician may determine to prioritize a higher sensitivity to ventricular events rather than a lower sensitivity to oversensing. In patients with relatively frequent SVT, if processing circuitry 312 did not switch back from the second sensing parameters to the first sensing parameters until the SVT episode ended as in the operation of FIG. 9, processing circuitry 312 could potentially sense using the second sensing parameters more frequently than the first sensing parameters. In some examples waiting a period of time to switch back to first sensing parameters instead of waiting until the SVT episode ends may facilitate more frequent use of the first sensing parameters.

[0096] In some examples, to determine whether to implement the example operation of FIG. 9 or the example operation of FIG. 10, processing circuitry of system 2, e.g., processing circuitry 312 of IMD 16, processing circuitry 402 of external device 24, processing circuitry of server 508, or processing circuitry of computing devices 506, may compare a frequency of SVT of the patient to an SVT threshold. For example, if the frequency of SVT meets the SVT threshold, processing circuitry of system 2 determines to implement the example operation of FIG. 10. If the frequency of SVT falls below the SVT threshold, processing circuitry of system 2 determines to implement the example operation of FIG. 9.Atly Ref. No. A0012169W001

[0097] Additionally, or alternatively, processing circuitry of system 2 may initially determine to implement the example operation of FIG. 9 and compare an amount of time sensing circuitry sensed the cardiac EGM signal using the second sensing parameters to a sensing parameter threshold to determine whether to switch to the example operation of FIG. 10. If the amount of time meets the sensing parameter threshold, processing circuitry of system 2 determines to implement the example operation of FIG. 10.

[0098] FIG. 11 is a flow diagram illustrating an example operation for determining whether to adjust a sensing parameter based on a patient HR, in accordance with one or more techniques of this disclosure. In some examples, in addition to or alternatively to adjusting one or more sensing parameters based on a determination that a patient, e.g., patient 14, is experiencing SVT, processing circuitry of system 10, e.g., processing circuitry 312 of IMD 16, may be configured to determine to adjust the one or more sensing parameters based on one or more of a patient HR, a patient HRV, noise in the cardiac EGM signal, a timing interval between an atria sense event and a ventricular sense event, or a variation in one or more R-waves, e.g., variation in duration, amplitude, or morphology.

[0099] Processing circuitry 312 may determine a patient HR of a patient, e.g., patient 14 (1102). In some examples, processing circuitry 312 determines the patient HR based on the cardiac EGM signal. In some examples, processing circuitry 312 may include oversensed T-waves and oversensed P-waves in the determination of the patient HR. In examples in which oversensed waveforms are included in the determination of the patient HR, processing circuitry 312 may expect patient HR to be artifactual and may determine, based on the determined patient HR including the artifacts, an indication of potential SVT episodes and / or sensing issues, which may facilitate appropriate therapy administration. In some examples, processing circuitry 312 may filter oversensed T-waves and oversensed P- waves from the signal to determine a “true” patient HR. In some examples, processing circuitry 312 determines the patient HR based on another physiological signal, e.g., a signal sensed via sensor(s) 306 of IMD 16. Processing circuitry 312 determines whether the patient HR is less than a low HR threshold (1104). If the patient HR is less than the low HR threshold (“YES” of 1104), processing circuitry 312 determines to adjust one or more sensing parameters, e.g., V-sensitivity threshold, from a first HR sensitivity threshold to a second HR sensitivity threshold. In some examples, the second HRAtty Ref. No. A0012169W001 sensitivity threshold is higher than the first HR sensitivity threshold. If the patient HR is greater than the low HR threshold (“NO” of 1104), processing circuitry 312 determines whether the patient HR is greater than a high HR threshold (1106). If the patient HR is greater than the high HR threshold (“YES” of 1106), processing circuitry 312 determines to adjust the V-sensitivity threshold from the first HR sensitivity threshold or the second HR sensitivity threshold to a third HR sensitivity threshold (1110). The third HR sensitivity threshold may be lower than the second HR sensitivity threshold. In examples in which processing circuitry 312 determines to adjust the V-sensitivity threshold from the second HR sensitivity to the third HR sensitivity threshold, the third HR sensitivity threshold may be the same as the first HR sensitivity threshold. Processing circuitry 312 continues to determine the patient HR based on the cardiac EGM (1102).

[0100] In some examples, the low HR threshold and the high HR threshold (HR thresholds) may be predetermined or programmable. The HR thresholds may be patientspecific. For example, a clinician and / or processing circuitry 312 may determine the HR thresholds or based on a disease progression, comorbidities, other conditions, or a combination thereof.

[0100] FIG. 12 is a flow diagram illustrating an example operation for determining to adjust a ventricular sensitivity threshold based on a noise level amplitude, in accordance with one or more techniques of this disclosure. Processing circuitry of system 10, e.g., processing circuitry 312, may perform the example operation of FIG. 12 on a periodic basis and / or in response to detecting a change in noise amplitude. Processing circuitry 312 determines a plurality of noise level amplitudes during a plurality of T-wave to R-wave intervals over a corresponding plurality of heartbeats (1202). Processing circuitry 312 may determine the plurality of noise level amplitudes during normal sinus rhythm and / or during an SVT episode. The T-wave to R-wave interval may be defined as a window starting 650 ms after onset of a ventricular sense event until an immediately subsequent ventricular sense event.

[0101] Processing circuitry 312 determines a representative noise level amplitude of the plurality of noise level amplitudes (1204). The representative noise level amplitude may be any statistical representation of the plurality of noise level amplitudes. In some examples, the representative noise level amplitude is a maximum noise level amplitude of the plurality of noise level amplitudes. In some examples, the representative noise levelAtty Ref. No. A0012169W001 amplitude is an average noise level amplitude of the plurality of noise level amplitudes. Based on the representative noise level amplitude, processing circuitry 312 adjusts the V- sensitivity threshold (1206). In some examples, adjusting the V-sensitivity threshold based on the representative noise level amplitude includes setting the V-sensitivity threshold to the representative noise level amplitude. In some examples, processing circuitry 312 may determine to temporarily adjust the V-sensitivity threshold based on the representative noise level amplitude during periods of time in which oversensing is relatively likely, e.g., during arrhythmia episodes or in high noise environments.

[0102] FIG. 13 is a flow diagram illustrating an example operation for setting the ventricular sensitivity threshold to a representative noise level amplitude, in accordance with one or more techniques of this disclosure. In some examples, the example operation of FIG. 13 may be a specific example of step 1206 of FIG. 12. Processing circuitry of system 10, e.g., processing circuitry 312, compares the representative noise level amplitude, e.g., the maximum noise level amplitude, to a current V-sensitivity threshold value (1302). Responsive to the V-sensitivity threshold value falling below the maximum noise level amplitude, processing circuitry 312 sets the V-sensitivity threshold to the maximum noise level amplitude (1304). In some examples, by setting the V-sensitivity threshold value to the maximum noise level amplitude, processing circuitry 312 may prevent noise from being misinterpreted, thereby preventing inappropriate withholding of therapy and / or unnecessary therapy administration, which may improve patient outcomes.

[0103] FIG. 14 is a flow diagram illustrating an example operation for adjusting the ventricular sensitivity threshold based on a risk of P-wave oversensing and / or T-wave oversensing, in accordance with one or more techniques of this disclosure. Processing circuitry of system 10, e.g., processing circuitry 312, determines a risk of oversensing based on an amplitude of a P-wave sensed by sensing circuitry 302 via an atrial lead, e.g., RA lead 22 of FIG. 2 (1402). In some examples, at a variety of atrial pacing amplitudes, processing circuitry 312 periodically, e.g., daily, assesses the risk of PWOS by mapping amplitudes of P-waves sensed via electrodes of RA lead 22 and expected amplitudes of P- waves sensed via a ventricular lead, e.g., far-field P-waves sensed via lead 18.

[0104] Processing circuitry 312 adjusts the V-sensitivity threshold based on the risk of oversensing (1404). In some examples, based on the risk of PWOS based on the amplitudeAtly Ref. No. A0012169W001 map, processing circuitry 312 sets the V-sensitivity threshold based on the expected amplitude of far-field P-waves.

[0105] Example 1. A medical device comprising: sensing circuitry configured to sense a cardiac electrogram (EGM) signal of a patient via one or more electrodes coupled to the medical device; and processing circuitry configured to: based on the cardiac EGM signal, determine the patient is experiencing a supraventricular tachycardia (SVT) episode; and based on the determination that the patient is experiencing the SVT episode, adjust one or more sensing parameters of sensing the cardiac EGM by the sensing circuitry, wherein the one or more sensing parameters include one or more of a ventricular blanking period or a ventricular sensitivity threshold, wherein to adjust the one or more sensing parameters, the processing circuitry is configured to adjust one or more of: the ventricular blanking period from a first period to a second period, wherein the second period is longer than the first period; or the ventricular sensitivity threshold from a first threshold to a second threshold, wherein the second threshold is higher than the first threshold.

[0106] Example 2. The medical device of example 1, further comprising signal generation circuitry configured to deliver cardiac resynchronization therapy.

[0107] Example 3. The medical device of any of examples 1-2, wherein the one or more electrodes comprise an integrated bipolar sensing vector.

[0108] Example 4. The medical device of any of examples 1-3, wherein the one or more electrodes are disposed on an integrated bipolar lead.

[0109] Example 5. The medical device of any of examples 1-4, wherein the processing circuitry is further configured to determine whether the SVT episode is an atrial fibrillation (AF) episode or an atrial flutter (AFL) episode.

[0110] Example 6. The medical device of any of examples 1-5, wherein the processing circuitry is further configured to: determine the patient is no longer experiencing the SVT episode; and adjust the one or more of the ventricular blanking period from the second period to the first period or the ventricular sensitivity threshold from the second threshold to the first threshold.

[0111] Example 7. The medical device of any of examples 1-6, wherein processing circuitry is configured to adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold for a period of time, and wherein the processing circuitry is further configured to: responsive to the first period of time meeting first time threshold,Atly Ref. No. A0012169W001 adjust the one or more of the ventricular blanking period from the second period to the first period or the ventricular sensitivity threshold from the second threshold to the first threshold for a second period of time; and responsive to the second period of time meeting a second time threshold, determine, based on the cardiac EGM, the patient is no longer experiencing the SVT episode.

[0112] Example 8. The medical device of any of examples 1-7, wherein to determine to adjust the one or more sensing parameters, the processing circuitry is further configured to at least: responsive to determining the patient is experiencing the SVT episode, identify potential oversensing; and responsive to identifying the potential oversensing, determine to adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold.

[0113] Example 9. The medical device of any of examples 1-8, wherein the processing circuitry is further configured to: adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold based on one or more of: patient heart rate (HR); patient HR variation (HRV); noise in the cardiac EGM signal; a timing interval between an atrial sense event and a ventricular sense event; or an R-wave variation in the cardiac EGM signal.

[0114] Example 10. The medical device of example 9, wherein to adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold based on the patient HR, the processing circuitry is configured to: adjust the ventricular sensitivity threshold from a first HR sensitivity threshold to a second HR sensitivity threshold when the patient HR falls below a low HR threshold, wherein the second HR sensitivity threshold is higher than the first HR sensitivity threshold; and adjust the ventricular sensitivity threshold from the first HR sensitivity threshold to a third HR sensitivity threshold when the patient HR meets a high HR threshold, wherein the third HR sensitivity threshold is lower than the first HR sensitivity threshold.

[0115] Example 11. The medical device of any of examples 9-10, wherein to adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold based on the noise of the cardiac EGM signal, the processing circuitry is configured to: determine a plurality of noise level amplitudes during a plurality T-wave to R-wave intervals over a corresponding plurality of beats; determine a representative noiseAtly Ref. No. A0012169W001 level amplitude of the plurality of noise level amplitudes; and adjust the ventricular sensitivity threshold based on the representative noise level amplitude.

[0116] Example 12. The medical device of example 11, wherein to adjust the ventricular sensitivity threshold based on the representative noise level amplitude, the processing circuitry is configured to at least: compare the representative noise level amplitude to a ventricular sensitivity threshold value; and responsive to the ventricular sensitivity threshold value falling below the representative noise level amplitude, set the ventricular sensitivity threshold to the representative noise level amplitude.

[0117] Example 13. The medical device of any of examples 1-12, wherein the one or more sensing parameters additionally comprises one or more of: an auto-adjusting decay time constant, an auto-adjusting boost, a number of intervals to detect ventricular fibrillation (VFNID), a number of intervals to detect ventricular tachycardia (VTNID), an AF rejection rule, or a P-wave rejection rule.

[0118] Example 14. The medical device of any of examples 1-13, wherein the processing circuitry is further configured to: determine a risk of oversensing based on an amplitude of a P-wave sensed by the sensing circuitry via an atrial lead coupled to the medical device; and adjust the ventricular sensitivity threshold based on the risk of oversensing.

[0119] Example 15. The medical device of example 14, wherein to determine the risk of oversensing based on the amplitude of the P-wave sensed by the sensing circuitry via the atrial lead coupled to the medical device, the processing circuitry is configured to: determine an expected far-field P-wave amplitude corresponding to the amplitude of the P-wave sensed by the sensing circuitry via the atrial lead, and wherein to adjust the ventricular sensitivity threshold based on the risk of oversensing, the processing circuitry is configured to: adjust the ventricular sensitivity based on the expected far-field P-wave amplitude.

[0120] Example 16. The medical device of any of examples 1-15, wherein the processing circuitry is further configured to: adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold within a 150 millisecond (ms) window immediately following an atrial sense event and between 250 ms and 650 ms immediately following a ventricular sense event.Atly Ref. No. A0012169W001

[0121] Example 17. A method comprising: sensing, by sensing circuitry of a medical device, a cardiac electrogram (EGM) signal of a patient via one or more electrodes coupled to the medical device; determining, by processing circuitry of the medical device and based on the cardiac EGM signal, the patient is experiencing a supraventricular tachycardia (SVT) episode; and adjusting, by the processing circuity and based on the determination that the patient is experiencing the SVT episode, one or more sensing parameters of sensing the cardiac EGM by the sensing circuitry, wherein the one or more sensing parameters include one or more of a ventricular blanking period or a ventricular sensitivity threshold, wherein to adjust the one or more sensing parameters, the processing circuitry is configured to adjust one or more of: the ventricular blanking period from a first period to a second period, wherein the second period is longer than the first period; or the ventricular sensitivity threshold from a first threshold to a second threshold, wherein the second threshold is higher than the first threshold.

[0122] Example 18. The method of example 17, wherein the medical device further comprises signal generation circuitry configured to deliver cardiac resynchronization therapy.

[0123] Example 19. The method of any of examples 17-18, wherein the one or more electrodes comprise an integrated bipolar sensing vector.

[0124] Example 20. The method of any of examples 17-19, wherein the one or more electrodes are disposed on an integrated bipolar lead.

[0125] Example 21. The method of any of examples 17-20, further comprising: determining, by the processing circuitry, whether the SVT episode is an atrial fibrillation (AF) episode or an atrial flutter (AFL) episode.

[0126] Example 22. The method of any of examples 17-21, further comprising: determining, by the processing circuitry, the patient is no longer experiencing the SVT episode; and adjusting, by the processing circuitry, the one or more of the ventricular blanking period from the second period to the first period or the ventricular sensitivity threshold from the second threshold to the first threshold.

[0127] Example 23. The method of any of examples 17-22, further comprising: adjusting, by the processing circuitry, the one or more of the ventricular blanking period or the ventricular sensitivity threshold for a period of time, wherein adjusting the one or more of the ventricular blanking period or the ventricular sensitivity threshold for the period ofAtly Ref. No. A0012169W001 time comprises: adjusting, by the processing circuitry and responsive to the first period of time meeting first time threshold, the one or more of the ventricular blanking period from the second period to the first period or the ventricular sensitivity threshold from the second threshold to the first threshold for a second period of time; and determining, by the processing circuitry and responsive to the second period of time meeting a second time threshold, based on the cardiac EGM, the patient is no longer experiencing the SVT episode.

[0128] Example 24. The method of any of examples 17-23, wherein determining to adjust the one or more sensing parameters comprises: identifying, by the processing circuitry and responsive to determining the patient is experiencing the SVT episode, potential oversensing; and determining, by the processing circuitry and responsive to identifying the potential oversensing, to adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold.

[0129] Example 25. The method of any of examples 17-24, further comprising: adjusting, by the processing circuitry, the one or more of the ventricular blanking period or the ventricular sensitivity threshold based on one or more of: patient heart rate (HR); patient HR variation (HRV); noise in the cardiac EGM signal; a timing interval between an atrial sense event and a ventricular sense event; or an R-wave variation in the cardiac EGM signal.

[0130] Example 26. The method of example 25, adjusting the one or more of the ventricular blanking period or the ventricular sensitivity threshold based on the patient HR comprises: adjusting, by the processing circuitry, the ventricular sensitivity threshold from a first HR sensitivity threshold to a second HR sensitivity threshold when the patient HR falls below a low HR threshold, wherein the second HR sensitivity threshold is higher than the first HR sensitivity threshold; and adjusting, by the processing circuitry, the ventricular sensitivity threshold from the first HR sensitivity threshold to a third HR sensitivity threshold when the patient HR meets a high HR threshold, wherein the third HR sensitivity threshold is lower than the first HR sensitivity threshold.

[0131] Example 27. The method of any of examples 25-26, wherein adjusting the one or more of the ventricular blanking period or the ventricular sensitivity threshold based on the noise of the cardiac EGM signal comprises: determining, by the processing circuitry, a plurality of noise level amplitudes during a plurality T-wave to R-waveAty Ref. No. A0012169W001 intervals over a corresponding plurality of beats; determining, by the processing circuitry, a representative noise level amplitude of the plurality of noise level amplitudes; and adjusting, by the processing circuitry, the ventricular sensitivity threshold based on the representative noise level amplitude.

[0132] Example 28. The method of example 27, wherein adjusting the ventricular sensitivity threshold based on the representative noise level amplitude comprises: comparing, by the processing circuitry, the representative noise amplitude to a ventricular sensitivity threshold value; and setting, by the processing circuitry and responsive to the ventricular sensitivity threshold value falling below the representative noise level amplitude, the ventricular sensitivity threshold to the representative noise level amplitude.

[0133] Example 29. The method of any of examples 17-28, wherein the one or more sensing parameters additionally comprises one or more of: an auto-adjusting decay time constant, an auto-adjusting boost, a number of intervals to detect ventricular fibrillation (VFNID), a number of intervals to detect ventricular tachycardia (VTNID), an AF rejection rule, or a P-wave rejection rule.

[0134] Example 30. The method of any of examples 17-29, further comprising: determining, by the processing circuitry, a risk of oversensing based on an amplitude of a P-wave sensed by the sensing circuitry via an atrial lead coupled to the medical device; and adjusting, by the processing circuitry, the ventricular sensitivity threshold based on the risk of oversensing.

[0135] Example 31. The method of example 30, wherein determining the risk of oversensing based on the amplitude of the P-wave sensed by the sensing circuitry via the atrial lead coupled to the medical device comprises: determining, by the processing circuitry, an expected far-field P-wave amplitude corresponding to the amplitude of the P- wave sensed by the sensing circuitry via the atrial lead, and wherein to adjust the ventricular sensitivity threshold based on the risk of oversensing, the processing circuitry is configured to: adjusting, by the processing circuitry, the ventricular sensitivity based on the expected far-field P-wave amplitude.

[0136] Example 32. The method of any of examples 17-31, further comprising: adjusting, by the processing circuitry, the one or more of the ventricular blanking period or the ventricular sensitivity threshold within a 150 millisecond (ms) window immediatelyAtly Ref. No. A0012169W001 following an atrial sense event and between 250 ms and 650 ms immediately following a ventricular sense event.

[0137] Example 33. A non-transitory computer-readable medium storing instructions that when executed cause processing circuitry to: based on a cardiac electrogram (EGM) signal sensed via one or more electrodes coupled to a medical device, determine a patient is experiencing a supraventricular tachycardia (SVT) episode; and based on the determination that the patient is experiencing the SVT episode, adjust one or more sensing parameters of sensing the cardiac EGM by the sensing circuitry, wherein the one or more sensing parameters include one or more of a ventricular blanking period or a ventricular sensitivity threshold, wherein to adjust the one or more sensing parameters, the processing circuitry is configured to adjust one or more of: the ventricular blanking period from a first period to a second period, wherein the second period is longer than the first period; or the ventricular sensitivity threshold from a first threshold to a second threshold, wherein the second threshold is higher than the first threshold.

[0138] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

Atly Ref. No. A0012169W001WHAT IS CLAIMED IS:

1. A medical device comprising: sensing circuitry configured to sense a cardiac electrogram (EGM) signal of a patient via one or more electrodes coupled to the medical device; and processing circuitry configured to: based on the cardiac EGM signal, determine the patient is experiencing a supraventricular tachycardia (SVT) episode; and based on the determination that the patient is experiencing the SVT episode, adjust one or more sensing parameters of sensing the cardiac EGM by the sensing circuitry, wherein the one or more sensing parameters include one or more of a ventricular blanking period or a ventricular sensitivity threshold, wherein to adjust the one or more sensing parameters, the processing circuitry is configured to adjust one or more of: the ventricular blanking period from a first period to a second period, wherein the second period is longer than the first period; or the ventricular sensitivity threshold from a first threshold to a second threshold, wherein the second threshold is higher than the first threshold.

2. The medical device of claim 1, further comprising signal generation circuitry configured to deliver cardiac resynchronization therapy.

3. The medical device of any of claims 1-2, wherein the one or more electrodes comprise an integrated bipolar sensing vector.

4. The medical device of any of claims 1-3, wherein the one or more electrodes are disposed on an integrated bipolar lead.

5. The medical device of any of claims 1-4, wherein the processing circuitry is further configured to determine whether the SVT episode is an atrial fibrillation (AF) episode or an atrial flutter (AFL) episode.Atly Ref. No. A0012169W0016. The medical device of any of claims 1-5, wherein the processing circuitry is further configured to: determine the patient is no longer experiencing the SVT episode; and adjust the one or more of the ventricular blanking period from the second period to the first period or the ventricular sensitivity threshold from the second threshold to the first threshold.

7. The medical device of any of claims 1-6, wherein processing circuitry is configured to adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold for a period of time, and wherein the processing circuitry is further configured to: responsive to the first period of time meeting first time threshold, adjust the one or more of the ventricular blanking period from the second period to the first period or the ventricular sensitivity threshold from the second threshold to the first threshold for a second period of time; and responsive to the second period of time meeting a second time threshold, determine, based on the cardiac EGM, the patient is no longer experiencing the SVT episode.

8. The medical device of any of claims 1-7, wherein to determine to adjust the one or more sensing parameters, the processing circuitry is further configured to at least: responsive to determining the patient is experiencing the SVT episode, identify potential oversensing; and responsive to identifying the potential oversensing, determine to adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold.

9. The medical device of any of claims 1-8, wherein the processing circuitry is further configured to: adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold based on one or more of: patient heart rate (HR); patient HR variation (HRV);Aty Ref. No. A0012169W001 noise in the cardiac EGM signal; a timing interval between an atrial sense event and a ventricular sense event; or an R-wave variation in the cardiac EGM signal.

10. The medical device of claim 9, wherein to adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold based on the patient HR, the processing circuitry is configured to: adjust the ventricular sensitivity threshold from a first HR sensitivity threshold to a second HR sensitivity threshold when the patient HR falls below a low HR threshold, wherein the second HR sensitivity threshold is higher than the first HR sensitivity threshold; and adjust the ventricular sensitivity threshold from the first HR sensitivity threshold to a third HR sensitivity threshold when the patient HR meets a high HR threshold, wherein the third HR sensitivity threshold is lower than the first HR sensitivity threshold.

11. The medical device of any of claims 9-10, wherein to adjust the one or more of the ventricular blanking period or the ventricular sensitivity threshold based on the noise of the cardiac EGM signal, the processing circuitry is configured to: determine a plurality of noise level amplitudes during a plurality T-wave to R- wave intervals over a corresponding plurality of beats; determine a representative noise level amplitude of the plurality of noise level amplitudes; and adjust the ventricular sensitivity threshold based on the representative noise level amplitude.

12. The medical device of claim 11, wherein to adjust the ventricular sensitivity threshold based on the representative noise level amplitude, the processing circuitry is configured to at least: compare the representative noise level amplitude to a ventricular sensitivity threshold value; andAtly Ref. No. A0012169W001 responsive to the ventricular sensitivity threshold value falling below the representative noise level amplitude, set the ventricular sensitivity threshold to the representative noise level amplitude.

13. The medical device of any of claims 1-12, wherein the one or more sensing parameters additionally comprises one or more of: an auto-adjusting decay time constant, an auto-adjusting boost, a number of intervals to detect ventricular fibrillation (VFNID), a number of intervals to detect ventricular tachycardia (VTNID), an AF rejection rule, or a P-wave rejection rule.

14. The medical device of any of claims 1-13, wherein the processing circuitry is further configured to: determine a risk of oversensing based on an amplitude of a P-wave sensed by the sensing circuitry via an atrial lead coupled to the medical device; and adjust the ventricular sensitivity threshold based on the risk of oversensing.

15. A non-transitory computer-readable medium storing instructions that when executed cause processing circuitry to: based on a cardiac electrogram (EGM) signal sensed via one or more electrodes coupled to a medical device, determine a patient is experiencing a supraventricular tachycardia (SVT) episode; and based on the determination that the patient is experiencing the SVT episode, adjust one or more sensing parameters of sensing the cardiac EGM by the sensing circuitry, wherein the one or more sensing parameters include one or more of a ventricular blanking period or a ventricular sensitivity threshold, wherein to adjust the one or more sensing parameters, the processing circuitry is configured to adjust one or more of: the ventricular blanking period from a first period to a second period, wherein the second period is longer than the first period; orAtly Ref. No. A0012169W001 the ventricular sensitivity threshold from a first threshold to a second threshold, wherein the second threshold is higher than the first threshold.

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