Synchronizing a first communication link and a second communication link

Abstract

In some examples, a first device includes a memory; and processing circuitry in communication with the memory. The processing circuitry is configured to initiate, via a first communication link, a first connection event with a second device according to a first connection event schedule and respond, via a second communication link, to a second connection event initiated by a third device according to a second connection event schedule. The processing circuitry is also configured to determine whether the second connection event conflicts with the first connection event schedule; and initiate, based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

Description

SYNCHRONIZING A FIRST COMMUNICATION LINK AND A SECOND COMMUNICATION LINK

[0001] This application claims the benefit of U.S. Provisional Patent Application Serial No. 63 / 585,313, filed September 26, 2023, the entire content of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present application relates to medical devices and, more particularly, medical devices configured to communicate wirelessly with one or more other devices.BACKGROUND

[0003] Implantable medical devices (IMDs) may be surgically implanted in a patient to monitor one or more physiological parameters of the patient and / or deliver therapy to suppress one or more symptoms of the patient. For example, an IMD may include a cardiac monitor, be configured to deliver cardiac pacing or another electrical therapy to the patient, and / or be configured to terminate tachyarrhythmia by delivery of high energy shocks. A clinician or patient may use one or more external devices to retrieve information collected by the IMD and / or to configure or adjust one or more parameters of the monitoring and / or therapy provided by the IMD. Typically, an external device connects to the IMD via a wireless connection. Additionally, or alternatively, external devices may connect to each other via wireless connections. A wireless connection may be established between devices using a Bluetooth® wireless protocol.SUMMARY

[0004] In general, the disclosure is directed to devices, systems, and techniques for synchronizing more than one communication link. For example, a device may communicate with one or more other devices according to a communication protocol. A communication link according to the communication protocol may involve, a “central” device that initiates a sequence of connection events with a “peripheral” device. Connection events may serve as a reference for timing data transmission and reception. For example, the central device and the peripheral device corresponding to the communication link may exchange data during windows of time corresponding to theconnection events initiated by the central device. In some cases, the central device controls the sequence of connection events corresponding to a communication link and the peripheral device does not have control over the sequence of connection events.

[0005] A first device may maintain more than one communication link according to the communication protocol. In some cases, the first device may communicate via a first communication link where the first device is the central device for the first communication link and a second device is the peripheral device for the first communication link. The first device may communicate via a second communication link where the first device is the peripheral device for the second communication link and a third device is the central device for the second communication link. Since the first device is the central device for the first communication link and the peripheral device for the second communication link, the first device may control connection events for the first communication link and not control connection events for the second communication link. The first device may control the connection events for the first communication link so that the first device is configured to use both communication links without conflict.

[0006] In some examples, a communication link may be associated with an amount of “slack.” Slack represents an extent to which connection event accuracy is higher than connection event uncertainty. When connection event accuracy is higher than connection event uncertainty, a device acting as a central device for the communication link may adjust connection events within a window of uncertainty to make room for connection events of another communication link where the device acts as a peripheral device. This may allow the device to synchronize two or more communication links. For example, by controlling connection events for communication links where the device is the central device, the device may synchronize the two or more-communication links even when the device does not control connection events for communication links where the device is a peripheral device.

[0007] The techniques of this disclosure may provide one or more advantages. For example, a device configured to control connection events for a first communication link where the device acts as a central device to accommodate another communication link where the device acts as a peripheral device may maintain higher quality communication via two or more communication links as compared with devices that do not control connection events to synchronize two or more communication links. Adjusting connectionevents within a window of uncertainty may allow a device to synchronize two or more communication links more effectively as compared with devices that do not adjust connection events based on a window of uncertainty. Furthermore, synchronizing two or more communication links involving implantable medical devices (IMDs) and external devices may allow a device to utilize limited amounts of communication circuitry.

[0008] In one example, a first device includes a memory; and processing circuitry in communication with the memory. The processing circuitry is configured to initiate, via a first communication link, a first connection event with a second device according to a first connection event schedule and respond, via a second communication link, to a second connection event initiated by a third device according to a second connection event schedule. The processing circuitry is also configured to determine whether the second connection event conflicts with the first connection event schedule; and initiate, based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

[0009] In another example, a method includes initiating, by processing circuitry of a first device via a first communication link, a first connection event with a second device according to a first connection event schedule, wherein the processing circuitry is in communication with a memory; and responding, by the processing circuitry via a second communication link, to a second connection event initiated by a third device according to a second connection event schedule. The method also includes determining, by the processing circuitry, whether the second connection event conflicts with the first connection event schedule; and initiating, by the processing circuitry based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

[0010] In another example, a non-transitory computer-readable medium includes instructions for causing one or more processors of a first device to: initiate, via a first communication link, a first connection event with a second device according to a first connection event schedule; and respond, via a second communication link, to a secondconnection event initiated by a third device according to a second connection event schedule. The instructions also cause the one or more processors to determine whether the second connection event conflicts with the first connection event schedule; and initiate, based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

[0011] 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 systems, devices, 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. Other features, objects, and advantages will be apparent from the description and drawings, and from the statements provided below.BRIEF DESCRIPTION OF DRAWINGS

[0012] FIGS. 1A-1C are conceptual diagrams illustrating an example medical device system including an implantable cardioverter defibrillator (ICD) system, in accordance with one or more techniques of this disclosure.

[0013] FIG. 2 is a block diagram illustrating an example configuration of components of the ICD system of FIG. 1 A, in accordance with one or more techniques of this disclosure.

[0014] FIG. 3 is a block diagram illustrating an example configuration of components of the first external device of FIG. 1 A, in accordance with one or more techniques of this disclosure.

[0015] FIG. 4 is a block diagram illustrating an example configuration of components of the second external device of FIG. 1 A, in accordance with one or more techniques of this disclosure.

[0016] FIG. 5 is a conceptual diagram illustrating a time plot of a first set of connection events corresponding to a first communication link and a second set of connection events corresponding to a second communication link, in accordance with one or more techniques of this disclosure.

[0017] FIG. 6 is a flow diagram illustrating an example operation for maintaining a first communication link and a second communication link, in accordance with one or more techniques of this disclosure.

[0018] FIG. 7 is a flow diagram illustrating an example operation for initiating connection events corresponding to first communication link and responding to connection events corresponding to second communication link.DETAILED DESCRIPTION

[0019] This disclosure describes techniques for establishing and maintaining communication by one or more devices of a medical device system. In some examples, communication is established between at least one implantable medical device (IMD) and at least one external device. An external device may, for example, initiate a communication link with the IMD, request data from the IMD, instruct the IMD to update one or more parameters of the IMD, or any combination thereof. Additionally, or alternatively, an external device may communicate with one or more other external devices. However, the techniques of this disclosure are not limited to IMDs, medical devices, or external device. The techniques may be used by any device to communicate with other entities. The techniques of this disclosure are also not limited to communication between the IMD and other devices. In some examples, an IMD or an external device may receive communications from a non-device source (e.g., receive human voice audio signals).

[0020] In some examples, an IMD records one or more physiological signals of a patient, where the one or more physiological signals may be indicative of a medical condition. The IMD may use any combination of electrodes, chemical sensors, temperature sensors, acoustic sensors, motion sensors, optical sensors, or other sensors to sense the physiological signals and store data indicative of the physiological signals in a memory. In some examples, the IMD delivers therapy, such as cardiac pacing or antitachyarrhythmia shocks, and stores data indicative of the therapy delivered. In some examples, the IMD records patient data without delivering therapy. In some examples, the IMD stores data regarding the status and performance of the IMD and components thereof, and operational parameters that control the functioning of the IMD, e.g., for sensing and / or delivering therapy.

[0021] Since the IMD is implanted within the patient, in some cases, the IMD may wirelessly communicate with an external device, e.g., to transmit at least some patient data to an external device for analysis by a clinician. Additionally, a user (e.g., the patient or the clinician) may provide user input to an external device to control the IMD. The external device may in turn transmit instructions to the IMD based on the user input. Some IMDs may communicate with external devices that are manufactured by the manufacturer of the IMD, but this is not necessary. In some examples, consumer electronic devices (e.g., tablets, computers, smart phones) may execute an application for communicating with an IMD in order to control the IMD, program one or more parameters of the IMD, send information to the IMD, request information from the IMD, or any combination thereof.

[0022] It may be beneficial for an external device to use one or more communication protocols (e.g., Bluetooth ® communication protocols such as Bluetooth Low Energy (BLE)) to communicate with the IMD, because consumer electronic devices may include communication circuitry such as a Bluetooth ® radios for communicating according to one or more communication protocols. According to one or more techniques described herein, an IMD may include a communication circuitry such as a Bluetooth ® radio in order to facilitate communication with consumer electronic external devices according to a communication protocol (e.g., a Bluetooth ® communication protocol). Additionally, or alternatively, an IMD may communicate with other IMDs according to the communication protocol. In some cases, an external device may communicate with another external device according to the communication protocol.

[0023] In some examples, an external device may communicate with an IMD via a first communication link and communicate with another external device via a second communication link. The external device may communicate via both of the first communication link and the second communication link using the same communication circuitry (e.g., the same Bluetooth ® radio). The external device may synchronize the first communication link and the second communication link so that the external device is configured to communicate via both of the first communication link and the second communication link without conflict. For example, the external device may communicate with the IMD using the communication circuitry during a first sequence of connection events and the external device may communicate with the other external device using the communication circuitry during a second sequence of connection events. The firstsequence of connection events may be at least partially interleaved with the second sequence of connection events so that the communication circuitry may communicate with the IMD while not communicating with the other external device and communicate with the other external device while not communicating with the IMD.

[0024] FIGS. 1A-1C are conceptual diagrams illustrating an example medical device system 2 including an implantable cardioverter defibrillator (ICD) system 8, in accordance with one or more techniques of this disclosure. FIG. 1A is a front view of a patient implanted with the ICD system 8. FIG. IB is a side view of the patient implanted with the ICD system 8. FIG. 1C is a transverse view of the patient implanted with the ICD system 8.

[0025] FIG. 1A is a conceptual diagram illustrating a front view of an example medical device system 2, in accordance with one or more techniques of this disclosure. In some examples, medical device system 2 may include an example ICD system 8. ICD system 8 includes an ICD 9 connected to an implantable medical lead 10. In some examples, ICD 9 may be configured to communicate wirelessly with first external device 40 and / or second external device 42.

[0026] ICD 9 may include a housing that forms a hermetic seal that protects components of the ICD 9. The housing of ICD 9 may be formed of a conductive material, such as titanium or titanium alloy, which may function as a housing electrode (sometimes referred to as a can electrode). In some embodiments, ICD 9 may be formed to have or may include a plurality of electrodes on the housing. ICD 9 may also include a connector assembly (also referred to as a connector block or header) that includes electrical feedthroughs through which electrical connections are made between conductors of lead 10 and electronic components included within the housing of ICD 9. As will be described in further detail herein, the housing may house one or more processors, memories, transmitters, receivers, sensors, sensing circuitry, therapy circuitry, power sources and other appropriate components. The housing is configured to be implanted in a patient, such patient 12.

[0027] ICD 9 may be implanted extra-thoracically on the left side of the patient, e.g., under the skin and outside the ribcage (subcutaneously or submuscularly). ICD 9 may, in some instances, be implanted between the left posterior axillary line and the left anterioraxillary line of the patient. ICD 9 may, however, be implanted at other extra-thoracic locations on the patient as described later.

[0028] Lead 10 may include an elongated lead body 13 having a distal portion 16 sized to be implanted in an extracardiovascular location proximate the heart, e.g., intra- thoracically, as illustrated in FIGS. 1A-1C, or extra-thoracically. For example, lead 10 may extend extra-thoracically under the skin and outside the ribcage (e.g., subcutaneously or submuscularly) from ICD 9 toward the center of the torso of the patient, for example, toward the xiphoid process 23 of the patient. At a position proximate xiphoid process 23, the lead body 13 may bend or otherwise turn and extend superiorly. The bend may be preformed and / or lead body 13 may be flexible to facilitate bending. In the example illustrated in FIGS. 1A-1C, the lead body 13 extends superiorly intra-thoracically underneath the sternum, in a direction substantially parallel to the sternum.

[0029] Distal portion 16 of lead 10 may reside in a substernal location such that distal portion 16 of lead 10 extends superior along the posterior side of the sternum substantially within the anterior mediastinum 36. Anterior mediastinum 36 may be viewed as being bounded laterally by pleurae 39, posteriorly by pericardium 38, and anteriorly by the sternum 22. In some instances, the anterior wall of anterior mediastinum 36 may also be formed by the transversus thoracis and one or more costal cartilages. Anterior mediastinum 36 includes a quantity of loose connective tissue (such as areolar tissue), adipose tissue, some lymph vessels, lymph glands, substernal musculature (e.g., transverse thoracic muscle), the thymus gland, branches of the internal thoracic artery, and the internal thoracic vein (ITV).

[0030] Lead body 13 may extend superiorly extra-thoracically (instead of intra- thoracically), e.g., either subcutaneously or submuscularly above the ribcage / sternum. Lead 10 may be implanted at other locations, such as over the sternum, offset to the right of the sternum, angled lateral from the proximal or distal end of the sternum, or the like. In some examples, lead 10 may be implanted within an extracardiac vessel within the thorax, such as the ITV, the intercostal veins, the superior epigastric vein, or the azygos, hemiazygos, and accessory hemiazygos veins. In some examples, distal portion 16 of lead 10 may be oriented differently than is illustrated in FIGS. 1A-1C, such as orthogonal or otherwise transverse to sternum 22 and / or inferior to heart 26. In such examples, distal portion 16 of lead 10 may be at least partially within anterior mediastinum 36. In someexamples, distal portion 16 of lead 10 may be placed between the heart and lung as well as within the pleural cavity.

[0031] Lead body 13 may have a generally tubular or cylindrical shape and may define a diameter of approximately 3-9 French (Fr). However, lead bodies of less than 3 Fr and more than 9 Fr may also be utilized. In another configuration, lead body 13 may have a flat, ribbon, or paddle shape with solid, woven filament, or metal mesh structure, along at least a portion of the length of the lead body 13. In such an example, the width across lead body 13 may be between 1-3.5 mm. Other lead body designs may be used without departing from the scope of this application.

[0032] Lead body 13 may be formed from a non-conductive material, including silicone, polyurethane, fluoropolymers, mixtures thereof, and other appropriate materials, and shaped to form one or more lumens (not shown), however, the techniques are not limited to such constructions. Distal portion 16 may be fabricated to be biased in a desired configuration, or alternatively, may be manipulated by the user into the desired configuration. For example, the distal portion 16 may be composed of a malleable material such that the user can manipulate the distal portion into a desired configuration where it remains until manipulated to a different configuration.

[0033] Distal portion 16 may include electrodes configured to deliver electrical energy to the heart or sense electrical signals of the heart. Distal portion 16 may be anchored to a desired position within the patient, for example, substernally or subcutaneously by, for example, suturing distal portion 16 to the patient’s musculature, tissue, or bone at the xiphoid process entry site. In some examples, distal portion 16 may be anchored to the patient or through the use of rigid tines, prongs, barbs, clips, screws, and / or other projecting elements or flanges, disks, pliant tines, flaps, porous structures such as a meshlike elements and metallic or non-metallic scaffolds that facilitate tissue growth for engagement, bio-adhesive surfaces, and / or any other non-piercing elements.

[0034] Lead body 13 may define a substantially linear portion 20 (FIG. 1A) as it curves or bends near the xiphoid process 23 and extends superiorly (e.g., cranially). As shown in FIG. 1A, at least a part of distal portion 16 may define an undulating configuration distal to the substantially linear portion 20. In particular, distal portion 16 may define an undulating pattern, e.g., zigzag, meandering, sinusoidal, serpentine, or other pattern, as it extends toward the distal end of lead 10. In other configurations, lead body 13may not have a substantially linear portion 20 as it extends superiorly, but instead the undulating configuration may begin immediately after the bend.

[0035] Distal portion 16 includes one or more defibrillation electrodes configured to deliver an anti-tachyarrhythmia, e.g., cardioversion / defibrillation, shock to heart 26 of patient 12. In some examples, distal portion 16 includes a plurality of defibrillation electrodes spaced a distance apart from each other along the length of distal portion 16. In the example illustrated by FIGS. 1A-1C, distal portion 16 includes two defibrillation electrodes 28a and 28b (collectively, “defibrillation electrodes 28”).

[0036] Defibrillation electrodes 28 may be disposed around or within the lead body 13 of the distal portion 16, or alternatively, may be embedded within the wall of the lead body 13. In one configuration, defibrillation electrodes 28 may be coil electrodes formed by a conductor. The conductor may be formed of one or more conductive polymers, ceramics, metal-polymer composites, semiconductors, metals or metal alloys, including but not limited to, one of a combination of the platinum, tantalum, titanium, niobium, zirconium, ruthenium, indium, gold, palladium, iron, zinc, silver, nickel, aluminum, molybdenum, stainless steel, MP35N, carbon, copper, polyaniline, polypyrrole, and other polymers. In another configuration, each of defibrillation electrodes 28 may be a flat ribbon electrode, a paddle electrode, a braided or woven electrode, a mesh electrode, a directional electrode, a patch electrode or another type of electrode configured to deliver a cardioversion / defibrillation shock to heart 26 of patient 12.

[0037] Defibrillation electrodes 28 may be electrically connected to one or more conductors, which may be disposed in the body wall of lead body 13 or in one or more insulated lumens (not shown) defined by lead body 13. In an example configuration, each of defibrillation electrodes 28 is connected to a common conductor such that a voltage may be applied simultaneously to all defibrillation electrodes 28 to deliver an antitachyarrhythmia shock to heart 26. In other configurations, defibrillation electrodes 28 may be attached to separate conductors such that each defibrillation electrode 28 may apply a voltage independent of the other defibrillation electrodes 28. In this case, ICD 9 or lead 10 may include one or more switches or other mechanisms to electrically connect the defibrillation electrodes together to function as a common polarity electrode such that a voltage may be applied simultaneously to all defibrillation electrodes 28 in addition to being able to independently apply a voltage.

[0038] Distal portion 16 may also include one or more pacing and / or sensing electrodes configured to deliver pacing pulses to heart 26 and / or sense electrical activity of heart 26. Such electrodes may be referred to as pacing electrodes, sensing electrodes, or pace / sense electrodes. In the example illustrated by FIGS. 1A-1C, distal portion 16 includes two pace / sense electrodes 32a and 32b (collectively, “pace / sense electrodes 32”).

[0039] In the illustrated example of FIGS. 1A-1C, pace / sense electrode 32b is positioned between defibrillation electrodes 28, e.g., within a gap between the defibrillation electrodes, and pace / sense electrode 32a is positioned more proximal along distal portion 16 than proximal defibrillation electrode 28a. In some examples, more than one electrode 32 may exist within the gap between defibrillation electrodes 28. In some examples, an electrode 32 is additionally or alternatively located distal of the distal defibrillation electrode 28b.

[0040] Electrodes 32 may be configured to deliver low-voltage electrical pulses to the heart or may sense a cardiac electrical activity, e.g., depolarization and repolarization of the heart. As such, electrodes 32 may be referred to herein as pace / sense electrodes 32. In one configuration, electrodes 32 are ring electrodes. However, in other configurations electrodes 32 may be any of a number of different types of electrodes, including ring electrodes, short coil electrodes, paddle electrodes, hemispherical electrodes, or directional electrodes. Each of electrodes 32 may be the same or different types of electrodes as others of electrodes 32. Electrodes 32 may be electrically isolated from an adjacent defibrillation electrode 28 by including an electrically insulating layer of material between electrodes 32 and adjacent defibrillation electrodes 28. Each electrode 32 may have its own separate conductor such that a voltage may be applied to or sensed via each electrode independently from another electrode 32.

[0041] Electrodes 28 are referred to as defibrillation electrodes, and electrodes 32 are referred to as pace / sense electrodes, because they may have different physical structures enabling different functionality. Defibrillation electrodes 28 may be larger, e.g., have greater surface area, than pace / sense electrodes 32 and, consequently, may be configured to deliver anti-tachyarrhythmia shocks that have relatively higher voltages than pacing pulses. The relatively smaller size of pace / sense electrodes 32 may provide advantages over defibrillation electrodes for delivering pacing pulses and sensing intrinsic cardiac activity, e.g., lower pacing capture thresholds and / or better sensed signal quality.Nevertheless, a defibrillation electrode 28 may be used to deliver pacing pulses and / or sense electrical activity of the heart, such as in combination with a pace / sense electrode 32.

[0042] In the configuration shown in FIGS. 1A-1C, each electrode 32 is substantially aligned along a major longitudinal axis (“x”). In one example, the major longitudinal axis is defined by a portion of lead body 13, e.g., substantially linear portion 20. In another example, the major longitudinal axis is defined relative to the body of the patient, e.g., along the anterior median line (or midsternal line), one of the sternal lines (or lateral sternal lines), left parasternal line, or other line.

[0043] In one configuration, the midpoint of each electrode 32a and 32b is along the major longitudinal axis “x,” such that each electrode 32a and 32b is at least disposed at substantially the same vertical position when the distal portion is implanted within the patient. In some examples, the longitudinal axis “x” may correspond to a caudal-cranial axis of the patient and a horizontal axis orthogonal to the longitudinal axis “x” may correspond to a medial-lateral axis of the patient. In other configurations, the electrodes 32 may be disposed at any longitudinal or horizontal position along the distal portion 16 disposed between, proximal to, or distal to the defibrillation electrodes 28. In the example illustrated in FIG. 1A, electrodes 32 are disposed along the undulating configuration of distal portion 16 at locations that will be closer to heart 26 of patient 12 than defibrillation electrodes 28 (e.g., at a peak of the undulating configuration that is toward the left side of the sternum). As illustrated in FIG. 1A, for example, electrodes 32 are substantially aligned with one another along the left sternal line. In the example illustrated in FIG. 1A, defibrillation electrodes 28 are disposed along peaks of the undulating configuration that extend toward a right side of the sternum away from the heart. This configuration places pace / sense electrodes 32 at locations closer to the heart than electrodes 28, to facilitate cardiac pacing and sensing at relatively lower amplitudes.

[0044] In some examples, pace / sense electrodes 32 and the defibrillation electrodes 28 may be disposed in a common plane when distal portion 16 is implanted extracardiovasculalry. In other configurations, the undulating configuration may not be substantially disposed in a common plane. For example, distal portion 16 may define a concavity or a curvature.

[0045] Proximal end 14 of lead body 13 may include one or more connectors 34 to electrically couple lead 10 to ICD 9. ICD 9 may also include a connector assembly that includes electrical feedthroughs through which electrical connections are made between the one or more connectors 34 of lead 10 and the electronic components included within the housing. The housing of ICD 9 may house one or more processors, memories, transmitters, receivers, sensors, sensing circuitry, therapy circuitry, power sources (e.g., capacitors and batteries), and / or other components. The components of ICD 9 may generate and deliver electrical therapy such as anti-tachycardia pacing, cardioversion or defibrillation shocks, post-shock pacing, and / or bradycardia pacing.

[0046] The undulating configuration of distal portion 16 and the inclusion of electrodes 32 between defibrillation electrodes 28 may provide a number of therapy vectors for the delivery of electrical therapy to the heart. For example, at least a portion of defibrillation electrodes 28 and one of electrodes 32 may be disposed over the right ventricle, or any chamber of the heart, such that pacing pulses and anti-tachyarrhythmia shocks may be delivered to the heart. The housing of ICD 9 may be charged with or function as a polarity different than the polarity of the one or more defibrillation electrodes 28 and / or electrodes 32 such that electrical energy may be delivered between the housing and the defibrillation electrode 28 and / or electrode 32 to the heart.

[0047] Each defibrillation electrode 28 may have the same polarity as every other defibrillation electrode 28 when a voltage is applied to it such that a shock may be delivered from all defibrillation electrodes together. In examples in which defibrillation electrodes 28 are electrically connected to a common conductor within lead body 13, this is the only configuration of defibrillation electrodes 28. However, in other examples, defibrillation electrodes 28 may be coupled to separate conductors within lead body 13 and may therefore each have different polarities such that electrical energy may flow between defibrillation electrodes 28, or between one of defibrillation electrodes 28 and one of pace / sense electrodes 32 or the housing electrode, to provide anti-tachyarrhythmia shock, pacing therapy, and / or to sense cardiac depolarizations. In this case, defibrillation electrodes 28 may still be electrically coupled together, e.g., via one or more switches within ICD 9, to have the same polarity.

[0048] In some examples, distal portion 16 of lead 10 may include one or more shields. The shield or shields may be configured to impede an electric field from deliveryof an electrical therapy via an electrode, e.g., from a pacing pulse, in a direction from the electrode away from the heart, e.g., in an anterior direction. In this manner, the shield may reduce the likelihood that the electrical field will stimulate extracardiac tissue, such as sensory or motor nerves. Furthermore, the shield may direct the electrical field toward the heart, allowing lower energy level pacing pulses to capture the heart than may be required without the shield. Lower energy pacing pulses may also reduce the likelihood that pacing pulses delivered via the pacing electrode stimulate extracardiac tissue and may result in less consumption of the power source of ICD 9 and, consequently, longer service life for the ICD. The techniques of this disclosure may be applied to implantable systems other than ICD 9, including, but not limited to, bradycardia pacemaker systems. For example, a lead that does not include defibrillation electrodes may include one or more shields and may be used with a pacemaker system without defibrillation capabilities.

[0049] In accordance with the techniques of the disclosure, the pacing electrode of pace / sense electrodes 32 may be configured to decrease the pacing voltage threshold. For example, a conductive surface may be disposed on a shield and electrically coupled to the pacing electrode, which may reduce a resistance of the pacing electrode and / or expand an electric field generated by the pacing electrode. Reducing the resistance of the pacing electrode and / or expanding the electric field generated by the pacing electrode may reduce an amount of current used to generate a pacing pulse, which may decrease an amount of power used by ICD 9.

[0050] For example, lead 10 may include proximal defibrillation electrode 28a and a distal defibrillation electrode 28b that are configured to deliver anti tachyarrhythmia shocks. In this example, pace / sense electrode 32b may be configured to deliver a pacing pulse that generates an electric field proximate to the pacing electrode. A shield may be disposed over at least a portion of an outer surface of pace / sense electrode 32b and extending laterally away from the pace / sense electrode 32b. The shield may be configured to impede the electric field in a direction from pace / sense electrode 32b away from the heart. In some examples, the shield may be disposed between proximal defibrillation electrode 28a and distal defibrillation electrode 28b. A conductive surface may be disposed on the shield and electrically coupled to pace / sense electrode 32b.

[0051] ICD 9 includes acoustic receiving circuitry configured to receive one or more acoustic signals. Acoustic signals may include one or more acoustic communicationsignals and / or one or more acoustic biometric signals. That is, the acoustic receiving circuitry of ICD 9 may be configured to sense one or more biometric signals that are indicative of physiological functions of the patient. For example, acoustic receiving circuitry may sense one or more heart sounds of the heart 26 of patient 12. ICD 9 may track one or more patient conditions based on heart sounds received via the acoustic receiving circuitry. For example, the heart sounds may indicate whether a heart failure condition of patient 12 is worsening. ICD 9 may, in some examples, deliver therapy based on acoustic biometric signals received via the acoustic receiving circuitry.

[0052] First external device 40 may include a housing which encloses processing circuitry electrically coupled to communication circuitry, a memory, and a user interface. In some examples, first external device 40 is physically separate from second external device 42. The user interface of first external device 40 may include, for example, at least one button. Additionally, or alternatively, the user interface of first external device 40 may include any other device, sensor, or medium configured for accepting user input. In some examples, the user interface of first external device 40 enables a user to initiate one or more techniques of this disclosure which establish a secure (e.g., encrypted) link with ICD 9 for a period of time. Although first external device 40 may be physically separated from second external device 42, first external device 40 is configured to, for example, establish a secure connection between second external device 42 and ICD 9. In some cases, first external device 40 may act as an intermediary for communication between second external device 42 and ICD 9, e.g., during a secure communication session. In other cases, first external device 40 may establish a secure link with ICD 9 without including any additional devices (e.g., second external device 42). First external device 40 may, in some cases, be referred to as a “relay” device.

[0053] In some examples, first external device 40 is configured for handheld use. In fact, a user may, in some cases, be able to fit first external device 40 in the palm of a single hand while interacting with the user interface using at least one finger. In addition to being configured for handheld use, first external device 40 may be configured to transmit signals via the communication circuitry according to at least one communication protocol. One communication protocol, for example, may enable first external device 40 to send signals to ICD 9 over a short range (e.g., less than about 20 cm). For example, first external device 40 may communicate via near-field communication technologies (e.g.,inductive coupling, Near-field Communication (NFC) or other communication technologies operable at ranges less than 10-20 cm). Another example communication protocol may enable ICD 9, first external device 40, and second external device 42 to communicate over a relatively longer range. For example, first external device 40 may communicate using far-field communication technologies (e.g., radiofrequency (RF) telemetry according to the 802.11 or Bluetooth® specification sets, or other communication technologies operable at ranges greater than near-field communication technologies). First external device 40 may communicate according to one or more Bluetooth® communication protocols such as BLE.

[0054] In some examples, the user interface of first external device 40 enables a user to initiate one or more techniques of this disclosure which establish communication with ICD 9 and / or second external device 42 for a period of time. First external device 40 is configured to, for example, establish a first communication link 44 between first external device 40 and ICD 9 via communication circuitry of first external device 40. Additionally, or alternatively, first external device 40 is configured to establish a second communication link 46 between first external device 40 and second external device 42 via the communication circuitry of second external device 42. In some examples, first communication link 44 and / or second communication link 46 may be according to a Bluetooth ® communication protocol such as BLE, but this is not required. First communication link 44 and / or second communication link 46 may be according to any communication protocol.

[0055] Second external device 42 may include a housing which encloses processing circuitry electrically coupled to communication circuitry, acoustic circuitry, a memory, and a user interface. The user interface of second external device 42 may include, for example, at least one button. Additionally, or alternatively, the user interface of second external device 42 may include any other device, sensor, or medium configured for accepting user input. In some examples, the user interface of second external device 42 enables a user to initiate one or more techniques of this disclosure which establish communication with ICD 9 and / or first external device 40 for a period of time. Second external device 42 is configured to, for example, establish second communication link 46 between first external device 40 and second external device 42 via the communication circuitry of second external device 42.

[0056] In some cases, second external device 42 may request information from ICD 9 via second communication link 46, first external device 40, and first communication link 44. In some cases, second external device 42 may instruct ICD 9 to update one or more parameters via second communication link 46, first external device 40, and first communication link 44. Second external device 42 may communicate with first external device 40 via second communication link 46. That is, second external device 42 may send information to first external device 40 for relay to ICD 9.

[0057] In some examples, second external device 42 may comprise a consumer electronic device such as a tablet, laptop computer, smart phone, or other smart device. Second external device 42 may be configured to execute an application for controlling and / or programming ICD 9. The application may include one or more user interface screens for display on a touch screen of second external device 42. The one or more user interface screens may receive one or more user inputs. In some cases, second external device 42 may communicate with ICD 9 in response to receiving one or more user inputs to the user interface screens of the application. In one or more examples where second external device 42 is a commercial electronic device, second external device 42 may include communication circuitry (e.g., a Bluetooth ® radio) configured for communication according to one or more open-source communication protocols (e.g., BLE and other Bluetooth ® protocols) that are accessible to a wide range of consumer electronic devices. Second external device 42 may additionally or alternatively include circuitry that is common in consumer electronics such as acoustic emitting circuitry, acoustic receiving circuitry, motion sensors, light sensors, temperature sensors, or any combination thereof.

[0058] In some examples, second external device 42 is configured for handheld use. In fact, a user may, in some cases, be able to fit second external device 42 in the palm of a single hand while interacting with the user interface using at least one finger. In addition to being configured for handheld use, second external device 42 may be configured to transmit signals via the communication circuitry according to at least one communication protocol and / or transmit signals via the acoustic circuitry according to at least one communication protocol. In some examples, ICD 9, first external device 40, and / or second external device 42 may communicate using one or more open-source communication protocols such as BLE, other Bluetooth ® communication protocols, or other open-source communication protocols.

[0059] Second external device 42 is configured to wirelessly communicate with ICD 9 as needed to provide or retrieve information. In some examples, second external device 42 acts as an external programming device, e.g., medical device programmer, for ICD 9. Second external device 42 is an external computing device that a user, e.g., the clinician and / or patient 12, may use to communicate with ICD 9. For example, second external device 42 may be a clinician programmer that the clinician uses to communicate with ICD 9 and update one or more settings of ICD 9. Additionally, or alternatively, second external device 42 may be a patient programmer that allows patient 12 to control certain operations of ICD 9 and / or view and modify one or more operational parameter values of ICD 9. The clinician programmer may include more programming features than the patient programmer. In other words, more complex or sensitive tasks may only be allowed by the clinician programmer to prevent an untrained patient from making undesired changes to ICD 9.

[0060] Second external device 42 may be a hand-held computing device with a display viewable by the user and an interface for providing input to second external device 42 (i.e., a user input mechanism). For example, second external device 42 may include a small display screen (e.g., a liquid crystal display (LCD) or a light emitting diode (LED) display) that presents information to the user. In addition, second external device 42 may include a touch screen display, keypad, buttons, a peripheral pointing device, voice activation, or another input mechanism that allows the user to navigate through the user interface of second external device 42 and provide input. If second external device 42 includes buttons and a keypad, the buttons may be dedicated to performing a certain function, e.g., a power button, the buttons and the keypad may be soft keys that change in function depending upon the section of the user interface currently viewed by the user, or any combination thereof.

[0061] In other examples, second external device 42 may be a larger workstation or a separate application within another multi-function device, rather than a dedicated computing device. For example, the multi-function device may be a notebook computer, tablet computer, workstation, one or more servers, cellular phone, personal digital assistant, or another computing device that may run an application that enables the computing device to operate as a secure device.

[0062] When second external device 42 is configured for use by the clinician, second external device 42 may be used to transmit instructions to ICD 9. Example instructions may include requests to set electrode combinations for sensing and / or stimulation. The clinician may also configure and store operational parameters for ICD 9 within ICD 9 with the aid of second external device 42. In some examples, second external device 42 assists the clinician in the configuration of ICD 9 by providing a system for identifying potentially beneficial operational parameter values.

[0063] Whether second external device 42 is configured for clinician or patient use, second external device 42 is configured to communicate with ICD 9 via second communication link 46, first external device 40, and first communication link 44. Second external device 42, for example, may communicate according to one or more open-source communication protocols such as BLE, other Bluetooth ® communication protocols, or other open-source communication protocols. For example, ICD 9 and second external device 42 may exchange information via second communication link 46, first external device 40, and first communication link 44 using one or more open-source communication protocols such as BLE, other Bluetooth ® communication protocols, or other open-source communication protocols. Additionally, or alternatively, second external device 42 and ICD 9 may exchange information via second communication link 46, first external device 40, and first communication link 44 using one or more proprietary communication protocols.

[0064] Communication protocols define sets of rules that define one or more aspects of data exchange between two or more entities of a network. In some examples, communication protocols are stored as lists of computer-readable instructions and communication protocols may be executed by any combination of hardware (e.g., physical circuitry) and software. An organization, such as a medical device manufacturer, may create its own communication protocols, license communication protocols from a third party, use open-source communication protocols, or perform any combination thereof. In some examples, a communication protocol includes security provisions, such as password requirements and data encryption in order to secure the transfer of data between two or more devices in a network.

[0065] ICD 9 collects physiological data from patient 12. ICD 9 may transmit physiological data collected from patient 12 to one or more external devices (e.g., firstexternal device 40 and / or second external device 42). Additionally, ICD 9 may receive data indicative of instructions from first external device 40 and / or second external device 42, where the instructions cause ICD 9 to, as examples, update one or more settings, change one or more parameters, output data, or delete data.

[0066] In some examples, first external device 40 may be configured to maintain two or more communication links according to a Bluetooth® protocol such as BLE, or another communication protocol. First external device 40 may, in some examples, use the same communication circuitry to communication via both of first communication link 44 and second communication link 46. The communication protocol may be associated with one or more connection events. For example, first communication link 44 may be associated with a first sequence of connection events and second communication link 46 may be associated with a second sequence of connection events. During each connection event of the first sequence of connection events, first external device 40 may communicate with ICD 9 via the first communication link 44. During each connection event of the second sequence of connection events, first external device 40 may communicate with second external device 42 via second communication link 46.

[0067] In some cases, the first sequence of connection events corresponding to the first communication link 44 may be at least partially interleaved with the second sequence of connection events corresponding to the second communication link 46. Since first external device 40 may use the same communication circuitry (e.g., the same Bluetooth® radio) to communicate via both of the first communication link 44 and the second communication link 46, it may be beneficial for first external device 40 to avoid communicating with second external device 42 when communicating with ICD 9, and to avoid communicating with ICD 9 when communicating with second external device 42. When the first sequence of connection events corresponding to the first communication link 44 are interleaved with the second sequence of connection events corresponding to the second communication link 46 so that connection events of the first sequence of connection events do not overlap with connection events of the second sequence of connection events at processing circuitry of first external device 40, first external device 40 may maintain both of first communication link 44 and second communication link 46 without conflict.

[0068] A communication protocol (e.g., BEE or another Bluetooth® protocol) corresponding to first communication link 44 and second communication link 46 may relyon a central device to initiate connection events with a peripheral device. BLE connection events, for example, may represent time intervals during which data exchange and synchronization between the central device and the peripheral device take place.Connection events may manage communication between the central device and the peripheral device. A connection interval may represent time between a start of two consecutive connection events of a sequence of connection events. A connection interval may be defined in a connection establishment phase. A central device and a peripheral device may negotiate the connection interval based on factors such as power consumption and desired data transfer rates. Shorter connection intervals allow for more frequent data exchanges and consume more power, and longer connection intervals allow for less frequent data exchange and consume less power.

[0069] A BLE communication link between a central device and a peripheral device may correspond to a sequence of connection events. A timing of the sequence of connection events may be synchronized between the central and peripheral devices. An interval between consecutive connection events may be consistent and defined by the connection interval. Timing of connection events may be controlled by the master device of a communication link. In some cases, the peripheral device of a communication link might not control timing of connection events.

[0070] Each connection event of a sequence of connection events for a communication link (e.g., first communication link 44 and / or second communication link 46) may include a set of connection event elements. For example, at the beginning of a connection event, a central device for the communication link may output a timing reference point referred to as an “anchor point” to the peripheral device for the communication link. The anchor point allows the peripheral device to synchronize a clock of the peripheral device with a clock of the central device. After the central device sends the anchor point, the central device may exchange data with the peripheral device. The peripheral device and / or the central device may, in some examples, send an acknowledgment (ACK) or negative acknowledgment (NACK) to indicate whether data was successfully received and processed. When a connection event concludes, the central device and the peripheral device may prepare for a subsequent connection event of the sequence of connection events.

[0071] In some examples, the central device for first communication link 44 may be first external device 40 and the peripheral device for first communication link 44 may beICD 9. The central device for second communication link 46 may be second external device 42 and the peripheral device for second communication link 46 may be first external device 40. This means that first external device 40 may initiate the first sequence of connection events with ICD 9 and the second external device 42 may initiate the second sequence of connection events with first external device 40. That is, first external device 40 may, in some examples, exercise control over the first sequence of connection events corresponding to first communication link 44 without exercising control over the second sequence of connection events corresponding to second communication link 46. To synchronize first communication link 44 and second communication link 46, first external device 40 may control the first set of connection events so that the first set of connection events do not overlap with the second set of connection events at processing circuitry of first external device 40.

[0072] In some examples, second external device 42 may establish second communication link 46. Second external device 42 may, in some examples, initiate second communication link 46. By initiating second communication link 46, second external device 42 may act as the central device for second communication link 46 and first external device 40 may act as the peripheral device for second communication link 46. In some examples, based on second communication link 46 being established, first external device 40 may establish first communication link 44. First external device 40 may, in some examples, initiate first communication link 44. By initiating first communication link 44, first external device 40 may act as the central device for first communication link 44 and ICD 9 may act as the peripheral device for first communication link 44.

[0073] Processing circuitry of first external device 40 may initiate, via a first communication link 44, a first connection event with ICD 9 according to a first connection event schedule. In some examples, the first connection event may be one of a first sequence of connection events corresponding to first communication link 44. The first connection event schedule may correspond to a time and / or a window of time corresponding to each connection event of the first sequence of connection events, a duration of each connection event of the first sequence of connection events, one or more other parameters of the first sequence of connection events, or any combination thereof. First external device 40 may control the first sequence of connection events. For example,first external device 40 may control one or more parameters corresponding to the first connection event schedule.

[0074] Processing circuitry of first external device 40 may respond, via second communication link 46, to a second connection event initiated by second external device 42 according to a second connection event schedule. The second connection event may be one of a second sequence of connection event corresponding to second communication link 46 and initiated by second external device 42. The second connection event schedule may correspond to a time and / or a window of time corresponding to each connection event of the second sequence of connection events, a duration of each connection event of the second sequence of connection events, one or more other parameters of the second sequence of connection events, or any combination thereof. Second external device 42 may control the second sequence of connection events. For example, second external device 42 may control one or more parameters corresponding to the second connection event schedule.

[0075] Since first external device 40 may exercise control over the first sequence of connection events corresponding to first communication link 44 without exercising control over the second sequence of connection events corresponding to second communication link 46, first external device 40 may control the first sequence of connection events to ensure that first communication link 44 and second communication link 46 are synchronized. For example, first external device 40 may ensure that windows of time during which first external device 40 initiates the first sequence of connection events with ICD 9 do not overlap with windows of time during which first external device 40 responds to the second sequence of connection events from second external device 42. This may involve ensuring that the first sequence of connection events is interleaved with the second sequence of connection events.

[0076] A communication link (e.g., first communication link 44 and / or second communication link 46) according to a communication protocol that relies on connection events (e.g., BLE or another Bluetooth® protocol) may be associated with an amount of slack. For example, connection events for first communication link 44 may be associated with an uncertainty value. Uncertainty may represent an unpredictability in the time of a connection event. Connection events for first communication link 44 may be associated with an extent to which the time of a connection event matches an expected time of aconnection event. Slack is the extent to which connection event accuracy is greater than connection event uncertainty. When connection event accuracy is greater than connection event uncertainty for connection events corresponding to first communication link 44, first external device 40 may use the resulting slack to control the first sequence of connection events corresponding to first communication link 44 to be in synchrony with the second sequence of connection events corresponding to second communication link 46.

[0077] In some examples, processing circuitry of first external device 40 may determine whether the second connection event received from second external device 42 conflicts with the first connection event schedule corresponding to the first sequence of connection events for first communication link 44. For example, the first connection event schedule corresponding to the first communication link 44 may include a schedule for initiating each connection event of a first sequence of connection events corresponding to first communication link 44. A target time window of a sequence of target time windows may follow each connection event of the first sequence of connection events corresponding to first communication link 44. To determine whether the second connection event received from second external device 42 conflicts with the first connection event schedule, the processing circuitry of first external device 40 is configured to determine whether the second connection event occurs within the target time window following the first connection event.

[0078] When the second connection event received from second external device 42 occurs within the target time window, this may mean that the second connection event does not conflict with the first connection event schedule for the sequence of connection events corresponding to first communication link 44. When the second connection event initiated by second external device 42 occurs outside of the target time window, this may mean that the second connection event conflicts with the first connection event schedule for the sequence of connection events corresponding to first communication link 44. For example, the target time window following each connection event of the first sequence of connection events corresponding to first communication link 44 may represent a window of time when first external device 40 may receive a connection event from second external device 42 that does not overlap with any of the first sequence of connection events corresponding to first communication link 44.

[0079] Processing circuitry of first external device 40 may initiate, with ICD 9 based on whether the second connection event conflicts with the first connection event schedule, a third connection event so that a fourth connection event initiated by the second external device 42 according to the second connection event schedule does not conflict with the first connection event schedule. For example, based on determining that the second connection event occurring within the target time window following the first connection event, the processing circuitry of first external device 40 is configured to initiate the third connection event at a planned connection event initiation time according to the first connection event schedule. Based on determining that the second connection event initiated by the second external device 42 occurs outside of the target time window following the first connection event initiated by first external device 40 with ICD 9, the processing circuitry of first external device 40 is configured to adjust the first connection event schedule to initiate the third connection event with ICD 9 at an adjusted connection event initiation time different from the planned connection event initiation time. By adjusting the first connection event schedule to initiate the third connection event with ICD 9 at an adjusted connection event initiation time, the processing circuitry of first external device 40 ensures that when first external device 40 responds to a fourth connection event initiated by second external device 42, the fourth connection event does not conflict with the first connection event schedule and the first communication link 44 is synchronized with the second communication link 46.

[0080] In some examples, based on determining that the second connection event initiated by the second external device 42 with the first external device 40 occurs before the target time window, the processing circuitry of first external device 40 is configured to initiate the third connection event with ICD 9 at the adjusted connection event initiation time occurring before the planned connection event initiation time. For example, when the second connection event initiated by the second external device 42 with the first external device 40 occurs before the target time window following the first connection event, this may indicate that future connection events initiated by second external device 42 via second communication link 46 may conflict with connection events initiated by first external device 40 with ICD 9 via first communication link 44 unless the first external device 40 adjusts the first connection event schedule so that connection events are initiated earlier.

[0081] In some examples, based on determining that the second connection event initiated by second external device 42 with first external device 40 occurs after the target time window, the processing circuitry of first external device 40 is configured to initiate the third connection event with ICD 9 at the adjusted connection event initiation time occurring after the planned connection event initiation time. For example, when the second connection event initiated by the second external device 42 with the first external device 40 occurs after the target time window following the first connection event, this may indicate that future connection events initiated by second external device 42 with first external device 40 via second communication link 46 may conflict with connection events initiated by first external device 40 with ICD 9 via first communication link 44 unless the first external device 40 adjusts the first connection event schedule so that connection events are initiated later.

[0082] The processing circuitry of first external device 40 may respond to the fourth connection event initiated by second external device 42 via the second communication link 46 after initiating the third connection event with ICD 9 via first communication link 44. The fourth connection event may occur within a target time window following the third connection event such that the fourth connection event does not conflict with the first connection event schedule for the first communication link 44. That is, based on determining whether the second connection event initiated by the second external device 42 conflicts with the first connection event schedule, first external device 40 may control the first connection event schedule so that the fourth connection event initiated by the second external device 42 does not conflict with the first connection event schedule.

[0083] In some examples, processing circuitry of the first external device 40 may determine that the second connection event initiated by the second external device 42 conflicts with the first connection event schedule corresponding to first communication link 44. Based on determining that the second connection event initiated by the second external device 42 conflicts with the first connection event schedule, processing circuitry of first external device 40 may identify an amount of connection event timing slack corresponding to first communication link 44. This may involve determining an extent to which an accuracy of connection event corresponding to first communication link 44 exceed an uncertainty of connection event corresponding to first communication link 44. When an accuracy of connection event corresponding to first communication link 44exceed the uncertainty of connection event corresponding to first communication link 44, first external device 40 may adjust the first connection event schedule within the available slack to synchronize first communication link 44 and second communication link 46.

[0084] Processing circuitry of the first external device 40 may adjust the first connection event schedule to initiate the third connection event within the amount of connection event timing slack corresponding to the first communication link 44. This may allow the first external device 40 to respond to the fourth connection event initiated by second external device 42 via second communication link 46 without conflicting with the first connection event schedule corresponding to the first communication link 44. That is, by controlling the first sequence of connection event initiated by first external device 40 with ICD 9 via second communication link 46, first external device 40 may synchronize the first communication link 44 and the second communication link 46 even when first external device 40 does not exercise control over the second sequence of connection event initiated by second external device 42 with first external device 40 via second communication link 46.

[0085] The techniques of this disclosure are not limited to communication involving medical devices. The techniques of this disclosure may be used by any kind of device to synchronize a first communication link and a second communication link. For example, any kind of first device may be a central device for a first communication link with a second device and a peripheral device for a second communication link with a third device. The first device may control connection events for the first communication link in order to synchronize the first communication link and the second communication link, even when the first device does not have control over connection events for the second communication link where the first device is the peripheral device.

[0086] FIG. IB is a conceptual diagram illustrating a side view of an example medical device system 2, in accordance with one or more techniques of this disclosure. For example, the side view illustrated in FIG. IB illustrates a distal portion 16 of the lead body 13 of lead 10. As seen in FIG. IB, the distal portion 16 of the lead body 13 is located within the xiphoid process 23 of the patient 12.

[0087] FIG. 1C is a conceptual diagram illustrating a transverse view of an example medical device system 2, in accordance with one or more techniques of this disclosure. Asseen in FIG. 1C, ICD 9 is implanted under the patient’s skin on a side of the patient and lead 10 is implanted within the xiphoid process 23 underneath the sternum 22.

[0088] Although the medical device system 2 of FIGS. 1A-1C illustrate an ICD system 8 including an ICD 9, other example medical device systems may include IMDs other than ICDs such as pacemakers, cardiac resynchronization therapy devices (CRT-Ds), insertable cardiac monitors (ICMs), spinal cord stimulation (SCS) devices, deep brain stimulation (DBS) devices, left ventricular assist devices (LVADs), implantable sensors, orthopedic devices, drug pumps, or any combination thereof. Techniques of this disclosure may be used for acoustic communication with any one of the aforementioned IMDs. Moreover, techniques described in this disclosure may be applied to facilitate communication between two or more devices, where none of the two or more devices are implantable devices. Additionally, in some examples, techniques described in this disclosure may be applied to facilitate acoustic communication between two or more devices, where none of the two or more devices are medical devices.

[0089] FIG. 2 is a block diagram illustrating an example configuration of components of ICD system 8, in accordance with one or more techniques of this disclosure. In the example of FIG. 2, ICD system 8 includes ICD 9 and electrodes 48. ICD system 8 may include one or more leads that include one or more of electrodes 48. ICD 9 includes processing circuitry 50, memory 52, sensing circuitry 54, stimulation generation circuitry 56, sensor(s) 58, communication circuitry 60, antenna 62, and power source 70, memory 52 is configured to store communication protocols 72, collected data 74, and operational parameters 76. In some examples, electrodes 48 may include defibrillation electrodes 28, pace / sense electrodes 32, one or more other electrodes, or any combination thereof.

[0090] Processing circuitry 50, in one example, may include one or more processors that are configured to implement functionality and / or process instructions for execution within ICD 9. For example, processing circuitry 50 may be capable of processing instructions stored in memory 52. Processing circuitry 50 may include, for example, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuitry. Accordingly, processing circuitry 50 may include any suitable structure, whether in hardware, software,firmware, or any combination thereof, to perform the functions ascribed herein to processing circuitry 50.

[0091] Memory 52 may be configured to store information within ICD 9 during operation. Memory 52 may include a computer-readable storage medium or computer- readable storage device. In some examples, memory 52 includes one or more of a shortterm memory or a long-term memory. Memory 52 may include, for example, random access memories (RAM), dynamic random-access memories (DRAM), static randomaccess memories (SRAM), magnetic discs, optical discs, flash memories, or forms of electrically programmable memories (EPROM) or electrically erasable and programmable memories (EEPROM). In some examples, memory 52 is used to store data indicative of instructions for execution by processing circuitry 50.

[0092] Sensing circuitry 54 monitors electrical cardiac signals from any combination of electrodes 48. In some examples, sensing circuitry 54 may include one or more amplifiers, filters, and analog-to-digital converters. For example, sensing circuitry 54 may include one or more detection channels, each of which may include an amplifier. The detection channels may be used to sense cardiac signals, such as a cardiac electrogram (EGM). Some detection channels may detect events, such as R-waves, P-waves, and T- waves and provide indications of the occurrences of such events to processing circuitry 50. Additionally, or alternatively, some channels may detect cardiac EGM signals from a particular combination of electrodes 48. One or more other detection channels may provide signals to an analog-to-digital converter, for conversion into a digital signal for processing, analysis, storage, or output by processing circuitry 50. Sensing circuitry 54 may be electrically coupled to some or all of electrodes 48, which may correspond to any of the defibrillation, pace / sense, and housing electrodes described herein. Sensing circuitry 54 is configured to obtain signals sensed via one or more combinations of electrodes 48 and process the obtained signals.

[0093] The components of sensing circuitry 54 may be analog components, digital components, or a combination thereof. Sensing circuitry 54 may, for example, include one or more sense amplifiers, filters, rectifiers, threshold detectors, analog-to-digital converters (ADCs) or the like. Sensing circuitry 54 may convert the sensed signals to digital form and provide the digital signals to processing circuitry 50 for processing or analysis. For example, sensing circuitry 54 may amplify signals from the sensing electrodes and convertthe amplified signals to multi-bit digital signals by an ADC. Sensing circuitry 54 may also compare processed signals to a threshold to detect the existence of atrial or ventricular depolarizations (e.g., P- waves or R- waves) and indicate the existence of the atrial depolarization (e.g., P-waves) or ventricular depolarizations (e.g., R-waves) to processing circuitry 50.

[0094] Processing circuitry 50 may process the signals from sensing circuitry 54 to monitor electrical activity of heart 26 of patient 12. Processing circuitry 50 may store signals obtained by sensing circuitry 54 as well as any generated EGM waveforms, marker channel data or other data derived based on the sensed signals in memory 52. Processing circuitry 50 may analyze the EGM waveforms and / or marker channel data to detect arrhythmias (e.g., bradycardia or tachycardia). In response to detecting the cardiac event, processing circuitry 50 may control stimulation generation circuitry 56 to deliver the desired therapy to treat the cardiac event, e.g., defibrillation shock, cardioversion shock, anti-tachy cardia pacing (ATP), post shock pacing, or bradycardia pacing.

[0095] Stimulation generation circuitry 56 is configured to generate and deliver electrical therapy to heart 26. Stimulation generation circuitry 56 may include one or more pulse generators, capacitors, and / or other components capable of generating and / or storing energy to deliver as pacing therapy, defibrillation therapy, cardioversion therapy, cardiac resynchronization therapy, other therapy, or a combination of therapies. In some instances, stimulation generation circuitry 56 may include a first set of components configured to provide pacing therapy and a second set of components configured to provide defibrillation therapy. In some instances, stimulation generation circuitry 56 may utilize the same set of components to provide both pacing and defibrillation therapy. In still other instances, stimulation generation circuitry 56 may share some of the defibrillation and pacing therapy components while using other components solely for defibrillation or pacing. Processing circuitry 50 may control stimulation generation circuitry 56 to deliver the generated therapy to heart 26 via one or more combinations of electrodes 48. Although not shown in FIG. 2, ICD 9 may include switching circuitry configurable by processing circuitry 50 to control which of electrodes 48 is connected to sensing circuitry 54 and stimulation generation circuitry 56.

[0096] As shown in FIG. 2, ICD 9 may additionally include one or more sensor(s) 58, such as one or more accelerometers, which may be configured to provide signalsindicative of other parameters of a patient, such as activity, posture, or temperature to processing circuitry 50 via sensing circuitry 54. In some examples, sensing circuitry 54 is electrically coupled to sensor(s) 58. Sensor(s) 58 may include any combination of accelerometers, temperature sensors, chemical sensors, light sensors, pressure sensors, acoustic sensors, or other kinds of sensor. Sensor(s) 58 may, for example, sense one or more physiological parameters indicative of a heart condition. Additionally, or alternatively, an accelerometer of sensor(s) 58 may sense data indicative of at least one of patient posture and patient activity.

[0097] Communication circuitry 60 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such as external device 11. For example, communication circuitry 60 may include appropriate modulation, demodulation, frequency conversion, filtering, and amplifier components for transmission and reception of data. Under the control of processing circuitry 50, communication circuitry 60 may receive downlink telemetry from, as well as send uplink telemetry to external device 11 or another device with the aid of an internal or external antenna, e.g., antenna 62. Communication circuitry 60 may include any combination of a Bluetooth ® radio, an electronic oscillator, frequency modulation circuitry, frequency demodulation circuitry, amplifier circuitry, and power switches such as a metal-oxide- semiconductor field-effect transistors (MOSFET), a bipolar junction transistor (BJT), an insulated-gate bipolar transistor (IGBT), a junction field effect transistor (JFET), or another element that uses voltage for its control.

[0098] Power source 70 is configured to deliver operating power to the components of ICD 9. Power source 70 may include a battery and a power generation circuit 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 external charging device. It is not required for power source 70 to be rechargeable. In some examples, power source 70 is not rechargeable, and ICD 9 is designed to operate on a single charge of power source 70. Power source 70 may include any one or more of a plurality of different battery types, such as nickel cadmium batteries and lithium-ion batteries.

[0099] Memory 52 may be configured to store communication protocols 72. In some examples, communication protocols 72 may include one or more Bluetooth ® communication protocols (e.g., BLE and / or other Bluetooth ® communication protocols) for sending and receiving communications via a Bluetooth ® radio of communication circuitry 60. In some examples, communication protocols 72 may include one or more communication protocols other than Bluetooth ® communication protocols for sending and receiving communications via communication circuitry 60. Communication protocols may include one or more rules, standards, or parameters for communicating with one or more other devices. For example, a communication protocol may include a frequency that communications are to be sent at, one or more rules for decoding communications, one or more rules for encoding communications, encryption rules, or any combination thereof.

[0100] In a connection according to a communication protocol of communication protocols 72 (e.g., a Bluetooth ® protocol) between a central device and a peripheral device, clock synchronization may be important for maintaining a stable and reliable communication link. Bluetooth ® communication may, for example, rely on timing established through a combination of RF events and low-energy mechanisms. BEE may use advertising and connection events to manage connection between a central device and a peripheral device. The peripheral device corresponding to a communication link may periodically broadcasts advertising packets. These packets may include information about the peripheral device, such as a device name, services offered, and other relevant data. A clock of the peripheral device might not be synchronized with a clock of a central device corresponding to the communication link during advertising.

[0101] When a central device establishes a connection with a peripheral device according to a Bluetooth ® protocol of communication protocols 72, the central device may send a connection request to the peripheral device. Based on the peripheral device accepting the connection request, the central device and the peripheral device may move to the connection phase. Once a communication link is established (e.g., first communication link 44 and / or second communication link 46 of FIG. 1), both the central device and the peripheral device may agree on a sequence of connection events. The sequence of connection events determines how often and / or for how long the central device and the peripheral device exchange data and synchronize their clocks.

[0102] In some examples, ICD 9 may represent a peripheral device for first communication link 44 between ICD 9 and first external device 40 according to the Bluetooth ® communication protocol of communication protocols 72. First external device 40 may represent a central device for the first communication link 44. During each connection interval of the sequence of communication intervals corresponding to first communication link 44, ICD 9 and first external device 40 may exchange data (e.g., collected data 74, instructions to update operational parameters 76, or other information). A timing of these exchanges may be managed by internal clocks of ICD 9 and first external device 40. Communication according to a Bluetooth ® protocol of communication protocols 72 between a central device and a peripheral device may rely on timing mechanisms established through connection intervals. The central device and the peripheral device may synchronize their internal clocks based on the agreed-upon sequence of connection events and by exchanging information during connection events of the sequence of connection events. This approach enables efficient and low-power communication while maintaining synchronization for data exchange.

[0103] In some examples, memory 52 is configured to store collected data 74. Collected data 74 may include any data sensed, processed, or analyzed by ICD 9, where the data is acquired via any combination of electrodes 48, sensor(s) 58, communication circuitry 60, and acoustic receiving circuitry 64. In some examples, collected data 74 includes a cardiac EGM recording sensed by sensing circuitry 54 via electrodes 48 and processed by processing circuitry 50. Collected data 74 may additionally or alternatively include data acquired by one or more chemical sensors of sensor(s) 58, motion data collected by one or more accelerometers of sensor(s) 58, temperature data, acoustic data, or any combination thereof. In some examples, collected data 74 is indicative of a presence of or a possibility of at least one heart condition (e.g., heart failure). In general, collected data 74 may represent physiological signals acquired from patient 12 over a period of time. In some examples, the period of time lasts for greater than 12 hours and less than 72 hours. In other examples, the period of time lasts for more than one week. In other examples, the period of time lasts for up to one month. Put another way, ICD 9 is configured to continuously monitor physiological signals over the period of time and store at least some of these physiological signals in memory 52 as collected data 74.

[0104] In some examples, memory 52 is configured to store operational parameters 76. Operational parameters 76 may govern aspects of the operation of ICD 9. For example, operational parameters 76 may include combinations of electrodes 48 and sensor(s) 58 for sensing physiological signals of patient 12. Additionally, or alternatively, operational parameters 76 may include a sampling rate for sampling analog signals sensed by electrodes 48 and sensor(s) 58. Operational parameters 76 may be updated based on instructions received from an external device (e.g., first external device 40 and / or second external device 42) via communication circuitry 60. In some examples, processing circuitry 50 of ICD 9 updates operational parameters 76 only if instructions to update operational parameters 76 are received over a secure link.

[0105] Processing circuitry 50 may, in some examples, use communication circuitry 60 to communicate with first external device 40 of FIG. 1 A via first communication link 44 of FIG. 1 A. In some examples, first external device 40 may initiate a first sequence of connection events with ICD 9 via the first communication link 44. During each connection event of the first sequence of connection events, ICD 9 and first external device 40 may exchange information (e.g., collected data 74, instructions to update operational parameters 76, other information, or any combination thereof) via first communication link 44. Outside of the sequence of connection events, first external device 40 and ICD 9 might not exchange information.

[0106] FIG. 3 is a block diagram illustrating an example configuration of components of first external device 40 in accordance with one or more techniques of this disclosure. In the example of FIG. 3, first external device 40 includes processing circuitry 80, memory 81, communication circuitry 82, antenna 84, user interface 86, and power source 88. Memory 81 is configured to store communication protocol(s) 90 including first communication link information 92 and second communication link information 94. Memory 81 is also configured to store IMD information 96 First external device 40 is not limited to the example configuration illustrated in FIG. 3. In some examples, first external device 40 may include another example configuration not illustrated in FIG. 3.

[0107] Processing circuitry 80, in one example, may include one or more processors that are configured to implement functionality and / or process instructions for execution within first external device 40. For example, processing circuitry 80 may be capable of processing instructions stored in memory 81. Processing circuitry 80 may include, forexample, microprocessors, DSPs, ASICs, FPGAs, or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuitry. Accordingly, processing circuitry 80 may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions ascribed herein to processing circuitry 80.

[0108] Memory 81 may be configured to store information within first external device 40 during operation. Memory 81 may include a computer-readable storage medium or computer-readable storage device. In some examples, memory 81 includes one or more of a short-term memory or a long-term memory. Memory 81 may include, for example, RAM, DRAM, SRAM, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. In some examples, memory 81 is used to store data indicative of instructions for execution by processing circuitry 80. Memory 81 may be used by software or applications running on first external device 40 to temporarily store information during program execution.

[0109] Communication circuitry 82 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such as ICD 9 and / or second external device 42. Under the control of processing circuitry 80, communication circuitry 82 may receive downlink telemetry from, as well as send uplink telemetry to ICD 9. Additionally, or alternatively, under the control of processing circuitry 80, communication circuitry 82 may receive downlink telemetry from, as well as send uplink telemetry to second external device 42. That is, communication circuitry 82 may both communicate with ICD 9 via first communication link 44 and communicate with second external device 42. This means that it may be beneficial for processing circuitry 80 to synchronize communication between first external device 40 and ICD 9 and communication between first external device 40 and second external device 42 so that the same communication circuitry 82 can handle communication with two separate devices (e.g., ICD 9 and second external device 42).

[0110] In some examples, communication circuitry 82 includes a first set of communication circuitry configured for transmitting and receiving signals according to a communication protocol developed by the manufacturer of ICD 9 or a third-party developer. In some examples, communication circuitry 82 further includes a second set of communication circuitry which defines a Bluetooth ® radio configured for transmittingand receiving signals according to Bluetooth ® communication protocols. However, communication circuitry 82 does not necessarily include separate sets of circuitry corresponding to different communication protocols. In some examples, communication circuitry 82 includes a single set of circuitry configured for transmitting and receiving signals according to a plurality of communication protocols. In some examples, communication circuitry 82 includes a single set of circuitry configured for transmitting and receiving signals according to one or more Bluetooth ® communication protocols without including circuitry for transmitting and receiving signals according to other communication protocols.

[0111] In some examples, communication circuitry 82 includes any one or combination of a Bluetooth ® radio, an electronic oscillator, frequency modulation circuitry, frequency demodulation circuitry, amplifier circuitry, and power switches such as a MOSFET, a BJT, an IGBT, a JFET, or another element that uses voltage for its control. When communication circuitry 82 includes a Bluetooth ® radio, first external device 40 may maintain two or more Bluetooth ® communication links (e.g., first communication link 44 and second communication link 46) via the same Bluetooth ® radio. Communication circuitry 82 is not limited to including one Bluetooth ® radio. In some examples, communication circuitry 82 includes more than one Bluetooth ® radio.

[0112] A user, such as a clinician or patient 12, may interact with first external device 40 through user interface 86. User interface 86 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 80 of first external device 40 and provide input. In one example, user interface 86 includes a single button which enables the user to instruct first external device 40 to execute one or more actions. For example, based on receiving a user input to user interface 86, first external device 40 may establish first communication link 44 with ICD 9. In some examples, user interface 86 also includes audio circuitry for accepting audio instructions.

[0113] Power source 88 is configured to deliver operating power to the components of first external device 40. Power source 88 may include a battery and a power generation circuit to produce the operating power. In some examples, the battery is rechargeable toallow extended operation. Recharging may be accomplished by electrically coupling power source 88 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 first external device 40. In other examples, traditional batteries (e.g., nickel cadmium or lithium-ion batteries) may be used. In addition, first external device 40 may be directly coupled to an alternating current outlet to operate.

[0114] First external device 40 may exchange information with other devices via communication circuitry 82 according to one or more communication protocol(s) 90. Communication protocol(s) 90, stored in memory 81, may include sets of computer- readable instructions that determine how data is transmitted and processed.Communication protocol(s) 90 may include one or more communication protocols that are additionally included in communication protocols 72 of FIG. 2. In other words, ICD 9 and first external device 40 may be configured to exchange information according to at least one common communication protocol. In some examples, the one or more common communication protocols include at least one Bluetooth ® communication protocol such as BLE. In some examples, communication protocol(s) 90 may include a set of communication protocols that are not available to ICD 9. Communication protocol(s) 90 may include one or more communication protocols that are additionally included in communication protocols 110 of FIG. 4. In other words, first external device 40 and second external device 42 may be configured to exchange information according to at least one common communication protocol. In some examples, the one or more common communication protocols include at least one Bluetooth ® communication protocol such as BLE. In some examples, communication protocol(s) 90 may include a set of communication protocols that are not available second external device 42.

[0115] First external device 40 may, in some examples, represent an intermediary between second external device 42 and ICD 9. First external device 40 may be referred to as a “relay” device. For example, first external device 40 may receive information from second external device 42 via second communication link 46 and forward the information to ICD 9 via first communication link 44. Additionally, or alternatively, first external device 40 may receive information from ICD 9 via first communication link 44 and forward the information to second external device 42 via second communication link 46.First external device 40 may use the same communication circuitry 82 to communicate via both of first communication link 44 and second communication link 46. In some examples, first external device 40 may use the same communication protocol of communication protocol(s) 90 to communicate via both of first communication link 44 and second communication link 46. In some examples, the communication protocol of communication protocol(s) 90 is a Bluetooth ® protocol such as BLE.

[0116] Communication protocol(s) 90 may include first communication link information 92 corresponding to first communication link 44 and second communication link information 94 corresponding to second communication link 46. First communication link information 92 may include information corresponding to one or more connection events corresponding to the first communication link 44. For example, first communication link information 92 may include information corresponding to a duration of one or more connection events of first communication link 44, a frequency of one or more connection events of first communication link 44, a duration of one or more connection intervals of first communication link 44, or any combination thereof. First communication link information 92 may include a clock accuracy corresponding to first external device 40, a clock uncertainty corresponding to first external device 40, a clock slack corresponding to first external device 40, or any combination thereof.

[0117] Second communication link information 94 may include information corresponding to one or more connection events corresponding to the second communication link 46. For example, second communication link information 94 may include information corresponding to a duration of one or more connection events of second communication link 46, a frequency of one or more connection events of second communication link 46, a duration of one or more connection intervals of second communication link 46, or any combination thereof. Second communication link information 94 may include a clock accuracy corresponding to second external device 42, a clock uncertainty corresponding to second external device 42, a clock slack corresponding to second external device 42, or any combination thereof.

[0118] In some examples, second external device 42 may initiate the second communication link 46 with first external device 40. Second external device 42 may initiate the second communication link 46 according to a Bluetooth ® protocol such as BEE. In some examples, second external device 42 may be a central device for secondcommunication link 46 and first external device 40 may be a peripheral device for second communication link 46. This means that second external device 42 may control a sequence of connection events corresponding to second communication link 46. In some examples, first external device 40 does not control the sequence of connection events corresponding to second communication link 46.

[0119] In some examples, based on second communication link 46 being established between second external device 42 and first external device 40, first external device 40 may initiate first communication link 44 with ICD 9. For example, first external device 40 may initiate first communication link 44 in response to a user input to user interface 86. First external device 40 may initiate the first communication link 44 according to a Bluetooth ® protocol such as BLE. In some examples, first external device 40 may be a central device for first communication link 44 and ICD 9 may be a peripheral device for first communication link 44. This means that first external device 40 may control a sequence of connection events corresponding to first communication link 44. In some examples, ICD 9 does not control the sequence of connection events corresponding to first communication link 44.

[0120] In some examples, a first sequence of connection events corresponding to first communication link 44 may be interleaved with a second sequence of connection events corresponding to second communication link 46. For example, each connection event of the first sequence of connection events may include a duration, and the first sequence of connection events may occur at a first connection event frequency. This means that there may be connection intervals between consecutive connection events of the first sequence of connection events. The second sequence of connection events may be interleaved with the first sequence of connection events so that connection events of the second sequence of connection events may occur within the connection intervals between consecutive connection events of the first sequence of connection events. This may allow first external device 40 to use the same communication circuitry 82 to communicate via both of the first communication link 44 and the second communication link 46.

[0121] Processing circuitry 80 of first external device 40 may synchronize the first communication link 44 and the second communication link 46 so that communication via the first communication link 44 and communication via the second communication link 46 do not conflict. Since processing circuitry 80 may be configured to control the firstsequence of connection events corresponding to first communication link 44 without controlling the second sequence of connection events corresponding to second communication link 46, processing circuitry 80 may control the first sequence of connection events to synchronize first communication link 44 and second communication link 46. In some examples, synchronizing first communication link 44 and second communication link 46 may involve controlling the first sequence of connection events so that the first sequence of connection events does not overlap with the second sequence of connection events.

[0122] Processing circuitry 80 may initiate, via first communication link 44, a first connection event with ICD 9 according to a first connection event schedule. In some examples, the first connection event schedule may be part of first communication link information 92. The first connection event schedule may include one or more planned connection event initiation times for the first sequence of connection events corresponding to first communication link 44. In some examples, the one or more planned connection event initiation times may represent planned anchor points for the first sequence of connection events. Processing circuitry 80 may initiate the first connection event at a planned connection event initiation time corresponding to the first connection event.

[0123] Processing circuitry 80 may respond, via second communication link 46, to a second connection event initiated by second external device 42 according to a second connection event schedule. The second connection event schedule may be part of second communication link information 94. In some examples, the second connection event may be part of a second sequence of connection events for second communication link 46 that are controlled by second external device 42. This means that processing circuitry 80 of first external device 40 might not be configured to control a time at which the second connection event occurs, because second external device 42 controls the second sequence of connection events.

[0124] In some examples, processing circuitry 80 determines whether the second connection event initiated by second external device 42 conflicts with the first connection event schedule corresponding to the first sequence of connection events initiated by first external device 40. In some examples, a target time window follows each connection event of the first sequence of connection events initiated by first external device 40 with ICD 9 via the first communication link 44. The target time windows may be part of firstcommunication link information 92 and / or second communication link information 94. In some examples, a connection event of the second sequence of connection events initiated by second external device 42 is expected to be initiated within the target time window following each connection event of the first sequence of connection events initiated by first external device 40. To determine whether the second connection event initiated by second external device 42 conflicts with the first connection event schedule for the first sequence of connection events initiated by first external device 40, processing circuitry 80 of first external device 40 may determine whether the second connection event occurs within a target time window following the first connection event.

[0125] Processing circuitry 80 of first external device 40 may initiate, based on whether the second connection event initiated by the second external device 42 conflicts with the first connection event schedule, a third connection event with ICD 9 so that a fourth connection event initiated by second external device 42 according to the second connection event schedule does not conflict with the first connection event schedule for the first sequence of connection events. For example, when the second connection event does conflict with the first connection event schedule, processing circuitry 80 may initiate the third connection event with ICD 9 without adjusting the first connection event schedule. But when the second connection event does conflict with the first connection event schedule, processing circuitry 80 may adjust the first connection event schedule to prevent future connection events initiated by second external device 42 from conflicting with the first connection event schedule.

[0126] Based on determining that the second connection event initiated by the second external device 42 occurs within the target time window following a first connection event initiated by first external device 40 with ICD 9, processing circuitry 80 may initiate a third connection event with ICD 9 at a planned connection event initiation time according to the first connection event schedule. That is, when the second connection event occurs within the target time window following the first connection event, this may indicate that the second connection event does not conflict with the first connection event schedule, and it is not necessary for processing circuitry 80 to adjust the first connection event schedule to synchronize first communication link 44 and second communication link 46.

[0127] Based on determining that the second connection event initiated by the second external device 42 occurs outside of the target time window following the first externaldevice 40 with ICD 9, processing circuitry 80 is configured to adjust the first connection event schedule to initiate a third connection event with ICD 9 at an adjusted connection event initiation time different from a planned connection event initiation time. That is, when the second connection event occurs outside of the target time window following the first connection event, this may indicate that the second connection event conflicts with the first connection event schedule and processing circuitry 80 may adjust the first connection event schedule to synchronize first communication link 44 and second communication link 46. In some examples, based on determining that the second connection event occurs before the target time window following the first connection event, processing circuitry 80 is configured to initiate the third connection event at the adjusted connection event initiation time occurring before the planned connection event initiation time. In some examples, based on determining that the second connection event occurs after the target time window following the first connection event, processing circuitry 80 is configured to initiate the third connection event at the adjusted connection event initiation time occurring after the planned connection event initiation time.

[0128] Processing circuitry 80 may respond to a fourth connection event initiated by second external device 42 according to the second connection event schedule. Since processing circuitry 80 controls the third connection event initiated with ICD 9 based on whether the second connection event initiated by second external device 42 conflicts with the first connection event schedule, the fourth connection event initiated by second external device 42 might not conflict with the first connection event schedule. That is, processing circuitry 80 may control the first sequence of communication events initiated by first external device 40 with ICD 9 so that the second sequence of communication events initiated by second external device 42 with first external device 40 do not conflict with the first sequence of communication events. Controlling the first sequence of communication events to not conflict with the second sequence of communication events may involve controlling the first sequence of communication events to be interleaved with the second sequence of communication events without overlap between communication events of the first sequence and communication events of the second sequence.

[0129] Processing circuitry 80 of first external device 40 may control the first sequence of connection pulses for first communication link 44 within an amount of timing slack corresponding to a clock of first external device 40. In some examples, timing slackmay represent an extent to which clock accuracy of first external device 40 is greater than a clock uncertainty of first external device 40. When clock accuracy is greater than clock uncertainty, this may allow first external device 40 to adjust the first sequence of communication events within a window of uncertainty to synchronize first communication link 44 and second communication link 46.

[0130] In some examples, processing circuitry 80 of first external device 40 may determine that a second connection event initiated by the second external device 42 conflicts with the first connection event schedule for the first sequence of connection events initiated by first external device 40 with ICD 9. Processing circuitry 80 may identify an amount of connection event timing slack corresponding to first communication link 44 (e.g., an amount of timing slack of a clock signal for first external device 40). Processing circuitry 80 may adjust the first connection event schedule to initiate the third connection event within the amount of connection event timing slack corresponding to the first communication link 44, allowing first external device 40 to respond to a fourth connection event initiated by second external device 42 without conflicting with the first connection event schedule.

[0131] In some examples, to identify the amount of connection event timing slack, processing circuitry 80 is configured to determine an accuracy corresponding to first communication link 44 (e.g., a clock accuracy of first external device 40). The accuracy may, in some examples, indicate how closely an actual frequency and an actual phase of a first sequence of connection events corresponding to the first communication link 44 match an intended frequency and an intended phase of the sequence of connection events. Processing circuitry 80 mat determine an uncertainty corresponding to the first communication link 44 (e.g., a clock uncertainty of first external device 40). The uncertainty may indicate an unpredictability in a time occurrence of the first sequence of connection events via the first communication link 44. Processing circuitry 80 may determine the connection event timing slack based on the accuracy and the uncertainty.

[0132] IMD information 96 may, in some examples, include collected data 74 collected by ICD 9, instructions to update operational parameters 76 of ICD 9, and other information corresponding to ICD 9. In some examples, first external device 40 may relay IMD information 96 between second external device 42 and ICD 9. That is, first externaldevice 40 may represent an intermediary device that relays information between second external device 42 and ICD 9.

[0133] FIG. 4 is a block diagram illustrating an example configuration of components of second external device 42, in accordance with one or more techniques of this disclosure. In the example of FIG. 4, second external device 42 includes processing circuitry 100, memory 101, communication circuitry 102, antenna 104, user interface 106, and power source 108. Memory 101 is configured to store communication protocol(s) 110 including communication link information 114. Memory 101 is also configured to store IMD information 116. Second external device 42 is not limited to the example configuration illustrated in FIG. 4. In some examples, second external device 42 may include another example configuration not illustrated in FIG. 4.

[0134] Processing circuitry 100, in one example, may include one or more processors that are configured to implement functionality and / or process instructions for execution within second external device 42. For example, processing circuitry 100 may be capable of processing instructions stored in memory 101. Processing circuitry 100 may include, for example, microprocessors, DSPs, ASICs, FPGAs, or equivalent discrete or integrated logic circuitry, or a combination of any of the foregoing devices or circuitry. Accordingly, processing circuitry 100 may include any suitable structure, whether in hardware, software, firmware, or any combination thereof, to perform the functions ascribed herein to processing circuitry 100.

[0135] Memory 101 may be configured to store information within second external device 42 during operation. Memory 101 may include a computer-readable storage medium or computer-readable storage device. In some examples, memory 101 includes one or more of a short-term memory or a long-term memory. Memory 101 may include, for example, RAM, DRAM, SRAM, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. In some examples, memory 101 is used to store data indicative of instructions for execution by processing circuitry 100. Memory 101 may be used by software or applications running on second external device 42 to temporarily store information during program execution.

[0136] Communication circuitry 102 may include any suitable hardware, firmware, software, or any combination thereof for communicating with another device, such first external device 40. Under the control of processing circuitry 100, communication circuitry102 may receive downlink telemetry from, as well as send uplink telemetry to first external device 40 via second communication link 46. In some examples, communication circuitry 102 includes a Bluetooth ® radio configured for transmitting and receiving signals according to Bluetooth ® communication protocols. In some examples, communication circuitry 102 includes any one or combination of a Bluetooth ® radio, an electronic oscillator, frequency modulation circuitry, frequency demodulation circuitry, amplifier circuitry, and power switches such as a MOSFET, a BJT, an IGBT, a JFET, or another element that uses voltage for its control. Communication circuitry 102 is not limited to including one Bluetooth ® radio. In some examples, communication circuitry 102 includes more than one Bluetooth ® radio.

[0137] A user, such as a clinician or patient 12, may interact with second external device 42 through user interface 106. User interface 106 includes a display (not shown), such as an LCD or LED display or other type of screen, with which processing circuitry 100 may present information (e.g., information retrieved from ICD 9, information related to parameters of ICD 9, other information). In addition, user interface 106 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 100 of second external device 42 and provide input. In other examples, user interface 106 also includes audio circuitry for providing audible notifications, instructions, or other sounds to patient 12, receiving voice commands from patient 12, or both. Memory 101 may include instructions for operating user interface 106 and for managing power source 108.

[0138] Power source 108 is configured to deliver operating power to the components of second external device 42. Power source 108 may include a battery and a power generation circuit to produce the operating power. In some examples, the battery is rechargeable to allow extended operation. Recharging may be accomplished by electrically coupling power source 108 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 second external device 42. In other examples, traditional batteries (e.g., nickelcadmium or lithium-ion batteries) may be used. In addition, second external device 42 may be directly coupled to an alternating current outlet to operate.

[0139] Second external device 42 may exchange information with other devices via communication circuitry 102 according to one or more communication protocol(s) 110. Communication protocol(s) 110, stored in memory 101, may include sets of computer- readable instructions that determine how data is transmitted and processed. Communication protocol(s) 110 may include one or more communication protocols that are additionally included in communication protocol(s) 90 of FIG. 3. In other words, first external device 40 second external device 42 may be configured to exchange information according to at least one common communication protocol. In some examples, the one or more common communication protocols include at least one Bluetooth ® communication protocol such as BLE. In some examples, communication protocol(s) 110 may include a set of communication protocols that are not available to first external device 40.

[0140] In some examples, second external device 42 may comprise a consumer electronic device such as a tablet, laptop computer, smart phone, or other smart device. Second external device 42 may be configured to execute an application for controlling and / or programming ICD 9. For example, second external device 42 may communicate with ICD 9 via second communication link 46, first external device 40, and first communication link 44. That is, first external device 40 may represent an intermediary between second external device 42 and ICD 9. First external device 40 may relay information sent from second external device 42 to ICD 9 and relay information sent from ICD 9 to second external device 42. Second external device 42 is not limited to using first external device 40 as an intermediary to communicate with ICD 9. In some examples, second external device 42 is configured to directly communicate with ICD 9 without an intermediary.

[0141] Communication protocol(s) 110 may include communication link information 114 corresponding to second communication link 46. In some examples, communication link information 114 may include at least some of the same information as second communication link information 94 of FIG. 3. Communication link information 114 may include information corresponding to one or more connection events corresponding to the second communication link 46. For example, communication link information 114 may include information corresponding to a duration of one or more connection events ofsecond communication link 46, a frequency of one or more connection events of second communication link 46, a duration of one or more connection intervals of second communication link 46, or any combination thereof. Communication link information 114 may include a clock accuracy corresponding to second external device 42, a clock uncertainty corresponding to second external device 42, a clock slack corresponding to second external device 42, or any combination thereof.

[0142] Processing circuitry 100 may initiate, via second communication link 46, a sequence of connection events with first external device 40 via second communication link 46 according to a connection event schedule. In some examples, the connection event schedule may be part of communication link information 114. The connection event schedule may include one or more planned connection event initiation times for the first sequence of connection events corresponding to first communication link 44. In some examples, the one or more planned connection event initiation times may represent planned anchor points for the first sequence of connection events. Processing circuitry 80 may initiate the first connection event at a planned connection event initiation time corresponding to the first connection event. IMD information 116 may, in some examples, include collected data 74 collected by ICD 9, instructions to update operational parameters 76 of ICD 9, and other information corresponding to ICD 9.

[0143] FIG. 5 is a conceptual diagram illustrating a time plot 200 of a first set of connection events 202 corresponding to a first communication link and a second set of connection events 204 corresponding to a second communication link, in accordance with one or more techniques of this disclosure. As seen in FIG. 5, time plot 200 includes a first set of connection events 202 including connection events 212A-212D and a second set of connection events 204 including connection events 222A-222D.

[0144] Connection events 212A-212D correspond to anchor points 214A-214D. For example, connection event 212A corresponds to anchor point 214A, connection event 212B corresponds to anchor point 214B, connection event 212C corresponds to anchor point 214C, and connection event 212D corresponds to anchor point 214D. In some examples, connection events 212A-212D are part of a first sequence of connection events initiated by first external device 40 with ICD 9 via first communication link 44. That is, first external device 40 may represent a central device for first communication link 44 andICD 9 may represent a peripheral device for first communication link 44. This means that first external device 40 may control a timing of connection events 212A-212D.

[0145] In some examples, each connection event of connection events 212A-212D may correspond to a target anchor point of target anchor points 216A-216D. For example, target anchor point 216A may correspond to connection event 212A, target anchor point 216B may correspond to connection event 212B, target anchor point 216C may correspond to connection event 212C, and target anchor point 216D may correspond to connection event 212D. In some examples, each of target anchor points 216A-216D may correspond to points at which an anchor point of a connection events of connection events 222A-222D is expected following a respective connection event of connection events 212A-212D. In some examples, each target anchor point of target anchor points 216A- 216D may correspond to a target time window of target time windows 218A-218D.

[0146] Connection events 222A-222D correspond to anchor points 224A-224D. For example, connection event 222A corresponds to anchor point 224A, connection event 222B corresponds to anchor point 224B, connection event 222C corresponds to anchor point 224C, and connection event 222D corresponds to anchor point 224D. In some examples, connection events 222A-222D are part of a second sequence of connection events initiated by second external device 42 with first external device 40 via second communication link 46. That is, second external device 42 may represent a central device for second communication link 46 and first external device 40 may represent a peripheral device for second communication link 46. This means that second external device 42 may control a timing of connection events 222A-222D.

[0147] In some examples, first external device 40 may be configured to initiate connection event 212A with ICD 9 via first communication link 44, connection event 212A having anchor point 214A. First external device 40 may respond to connection event 222 A initiated by second external device 42, the connection event 222 A including anchor point 224A. First external device 40 may determine whether anchor point 224A occurs within target time window 218A corresponding to a target anchor point 216A. That is, first external device 40 may determine whether anchor point 224A of connection event 222A initiated by second external device 42 occurs within a target time window 218A following connection event 212A. Since anchor point 224A occurs within target time window 218A,first external device 40 may initiate connection event 212B at a planned connection event initiation time.

[0148] First external device 40 may determine whether anchor point 224B occurs within target time window 218B corresponding to a target anchor point 216A. That is, first external device 40 may determine whether the anchor point 224B of connection event 222B initiated by second external device 42 occurs within a target time window 218B following connection event 212B. Since the anchor point 224B of connection event 222B initiated by second external device 42 occurs outside of the target time window 218B following connection event 212B, this may indicate that connection event 212B conflicts with a connection event schedule corresponding to connection events 212A-212D.

[0149] In some examples, first external device 40 may adjust the connection event schedule to initiate connection event 212C with ICD 9 via first communication link 44 so that connection event 222C initiated by second external device 42 does not conflict with the connection event schedule corresponding to connection events 212A-212D. For example, since anchor point 224B of connection event 222B occurs after target time window 218B, first external device 40 may adjust the connection event schedule to initiate connection event 212C at an adjusted connection event initiation time following a planned connection event initiation time for connection event 212C. This may cause first external device 40 to respond to connection event 222C initiated by second external device 42 in a way that does not conflict with the connection event schedule for connection events 212A-212D. For example, as seen in FIG. 5, the anchor point 224C of connection event 222C initiated by second external device 42 occurs within the target time window 218C following connection event 212C, indicating that connection event 222C does not conflict with the connection event schedule for connection events 212A-212D.

[0150] Since anchor point 224C occurs within target time window 218C, first external device 40 may initiate connection event 212D at a planned connection event initiation time. First external device 40 may respond to connection event 222D initiated by second external device 42, the connection event 222D including anchor point 224D. First external device 40 may determine whether anchor point 224D occurs within target time window 218D corresponding to a target anchor point 216D. That is, first external device 40 may determine whether the anchor point 224D of connection event 222D initiated by second external device 42 occurs within a target time window 218D following connection event212D. Since the anchor point 224D of connection event 222D initiated by second external device 42 occurs outside of the target time window 218D following connection event 212D, this may indicate that connection event 212B conflicts with a connection event schedule corresponding to connection events 212A-212D. First external device 40 may adjust the connection event schedule corresponding to connection events 212A-212D so that a connection event initiated by first external device 40 after connection event 212D occurs prior to a planned connection event initiation time.

[0151] FIG. 6 is a flow diagram illustrating an example operation for maintaining a first communication link 44 and a second communication link 46, in accordance with one or more techniques of this disclosure. The example operation is described with respect to ICD 9, first external device 40, and second external device 42 of FIGS. 1A-4, and components thereof. However, the techniques of FIG. 6 may be performed by different components of ICD 9, first external device 40, and second external device 42, or by additional or alternative medical device systems.

[0152] First external device 40 may maintain a first communication link 44 as a central device (302). In some examples, first external device 40 may communicate with the ICD 9 via first communication link 44. ICD 9 may represent a peripheral device according to the first communication link 44. First external device 40 may maintain a second communication link 46 as a peripheral device (304). In some examples, first external device 40 may communicate with second external device 42 via second communication link 46. Second external device 42 may represent a peripheral device according to the second communication link 46. In some examples, first external device 40 may initiate a first sequence of connection events with ICD 9 via first communication link 44 and second external device 42 may initiate a second sequence of connection events with first external device 40 via second communication link 46.

[0153] First external device 40 may determine whether a connection event for the second communication link 46 occurs within a target time window (306) following a connection event for the first communication link 44. When the connection event for the second communication link 46 occurs within the target time window following the connection event for the first communication link 44 (“YES” at block 306), the example operation may return to block 306. When the connection event for the second communication link 46 does not occur within the target time window following theconnection event for the first communication link 44, first external device 40 may determine whether the connection event for the second communication link 46 occurs before the target time window (308).

[0154] When the connection event for the second communication link 46 does not occur before the target time window (“NO” at block 308), first external device 40 may shift a connection event for the first communication link 44 backward (310). When the connection event for the second communication link 46 occurs before the target time window (“YES” at block 308), first external device 40 may shift a connection event for the first communication link 44 backward (312). That is, first external device 40 may control the first sequence of connection events for first communication link 44 in order to synchronize first communication link 44 and second communication link 46 without controlling the second sequence of connection events for second communication link 46.

[0155] FIG. 7 is a flow diagram illustrating an example operation for initiating connection events corresponding to first communication link 44 and responding to connection events corresponding to second communication link 46. The example operation is described with respect to ICD 9, first external device 40, and second external device 42 of FIGS. 1A-4, and components thereof. However, the techniques of FIG. 7 may be performed by different components of ICD 9, first external device 40, and second external device 42, or by additional or alternative medical device systems.

[0156] First external device 40 may initiate, via first communication link 44, a first connection event with ICD 9 according to a first connection event schedule (402) for a first plurality of connection events. In some examples, first external device 40 may initiate the first plurality of connection events with ICD 9 via first communication link 44 according to the first connection event schedule. First external device 40 may respond, via the second communication link 46, to a second connection event initiated by second external device 42 according to a second connection event schedule (404). In some examples, second external device 42 may initiate the second plurality of connection events with first external device 40 via second communication link 46 according to the second connection event schedule.

[0157] First external device 40 may determine whether the second connection event conflicts with the first connection event schedule (406). In some examples, to determine whether the second connection event conflicts with the first connection event schedule,first external device 40 may determine whether the second connection event occurs within a target time window following the first connection event. First external device 40 may initiate, based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by a second external device 42 according to the second connection event schedule does not conflict with the first connection event schedule (408).

[0158] The following examples are a non-limiting list of clauses in accordance with one or more techniques of this disclosure.

[0159] Clause 1. A first device comprising a memory and processing circuitry in communication with the memory. The processing circuitry is configured to initiate, via a first communication link, a first connection event with a second device according to a first connection event schedule and respond, via a second communication link, to a second connection event initiated by a third device according to a second connection event schedule. The processing circuitry is also configured to determine whether the second connection event conflicts with the first connection event schedule; and initiate, based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

[0160] Clause 2. The first device of clause 1, wherein the first device represents a central device according to the first communication link and the second device represents a peripheral device according to the first communication link, wherein the first device represents a peripheral device according to the second communication link and the third device represents a central device according to the second communication link, wherein the central device according to the first communication link is configured to control the first connection event schedule, and wherein the central device according to the second communication link is configured to control the second connection event schedule.

[0161] Clause 3. The first device of any of clauses 1-2, wherein the processing circuitry is further configured to respond to the fourth connection event initiated by the third device according to the second connection event schedule, wherein the fourth connection event does not conflict with the first connection event schedule.

[0162] Clause 4. The first device of any of clauses 1-3, wherein the first connection event schedule corresponding to the first communication link comprises a schedule for initiating each connection event of a sequence of connection events corresponding to the first communication link, the sequence of connection events including the first connection event and the third connection event, wherein a target time window of a sequence of target time windows follows each connection event of the sequence of connection events, and wherein to determine whether the second connection event conflicts with the first connection event schedule, the processing circuitry is configured to determine whether the second connection event occurs within the target time window following the first connection event.

[0163] Clause 5. The first device of clause 4, wherein based on determining that the second connection event occurs within the target time window, the processing circuitry is configured to initiate the third connection event at a planned connection event initiation time according to the first connection event schedule, and wherein based on determining that the second connection event occurs outside of the target time window, the processing circuitry is configured to adjust the first connection event schedule to initiate the third connection event at an adjusted connection event initiation time different from the planned connection event initiation time.

[0164] Clause 6. The first device of clause 5, wherein based on determining that the second connection event occurs before the target time window, the processing circuitry is configured to initiate the third connection event at the adjusted connection event initiation time occurring before the planned connection event initiation time, and wherein based on determining that the second connection event occurs after the target time window, the processing circuitry is configured to initiate the third connection event at the adjusted connection event initiation time occurring after the planned connection event initiation time.

[0165] Clause 7. The first device of any of clauses 1-6, wherein the processing circuitry is further configured to: determine that the second connection event conflicts with the first connection event schedule; identify an amount of connection event timing slack corresponding to the first communication link; and adjust the first connection event schedule to initiate the third connection event within the amount of connection event timing slack corresponding to the first communication link, allowing the first device torespond to the fourth connection event without conflicting with the first connection event schedule.

[0166] Clause 8. The first device of clause 7, wherein to identify the amount of connection event timing slack, the processing circuitry is configured to: determine an accuracy corresponding to the first communication link, the accuracy indicating how closely an actual frequency and an actual phase of a sequence of connection events corresponding to the first communication link match an intended frequency and an intended phase of the sequence of connection events; determine an uncertainty corresponding to the first communication link, the uncertainty indicating an unpredictability in a time occurrence of the sequence of connection events via the first communication link; and determine the connection event timing slack based on the accuracy and the uncertainty.

[0167] Clause 9. The first device of any of clauses 1-8, wherein the processing circuitry is further configured to adjust the first connection event schedule so that each connection event of a set of connection events initiated by the third device following the fourth connection event do not conflict with the first connection event schedule.

[0168] Clause 10. The first device of any of clauses 1-9, wherein the first device comprises a first external device, wherein the second device comprises a medical device configured to be implanted underneath a skin of a patient, and the third device comprises a second external device.

[0169] Clause 11. A method includes initiating, by processing circuitry of a first device via a first communication link, a first connection event with a second device according to a first connection event schedule, wherein the processing circuitry is in communication with a memory and responding, by the processing circuitry via a second communication link, to a second connection event initiated by a third device according to a second connection event schedule. The method also includes determining, by the processing circuitry, whether the second connection event conflicts with the first connection event schedule; and initiating, by the processing circuitry based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

[0170] Clause 12. The method of clause 11, wherein the first device represents a central device according to the first communication link and the second device represents a peripheral device according to the first communication link, wherein the first device represents a peripheral device according to the second communication link and the third device represents a central device according to the second communication link, wherein the central device according to the first communication link is configured to control the first connection event schedule, and wherein the central device according to the second communication link is configured to control the second connection event schedule.

[0171] Clause 13. The method of any of clauses 11-12, further comprising responding, by the processing circuitry to the fourth connection event initiated by the third device according to the second connection event schedule, wherein the fourth connection event does not conflict with the first connection event schedule.

[0172] Clause 14. The method of any of clauses 11-13, wherein the first connection event schedule corresponding to the first communication link comprises a schedule for initiating each connection event of a sequence of connection events corresponding to the first communication link, the sequence of connection events including the first connection event and the third connection event, wherein a target time window of a sequence of target time windows follows each connection event of the sequence of connection events, and wherein determining whether the second connection event conflicts with the first connection event schedule comprises determining, by the processing circuitry, whether the second connection event occurs within the target time window following the first connection event.

[0173] Clause 15. The method of clause 14, wherein based on determining that the second connection event occurs within the target time window, the method further comprises initiating, by the processing circuitry, the third connection event at a planned connection event initiation time according to the first connection event schedule, and wherein based on determining that the second connection event occurs outside of the target time window, the method further comprises adjusting, by the processing circuitry, the first connection event schedule to initiate the third connection event at an adjusted connection event initiation time different from the planned connection event initiation time.

[0174] Clause 16. The method of clause 15, wherein based on determining that the second connection event occurs before the target time window, the method further comprises initiating, by the processing circuitry, the third connection event at the adjusted connection event initiation time occurring before the planned connection event initiation time, and wherein based on determining that the second connection event occurs after the target time window, the method further comprises initiating, by the processing circuitry, the third connection event at the adjusted connection event initiation time occurring after the planned connection event initiation time.

[0175] Clause 17. The method of any of clauses 11-16, further comprising: determining, by the processing circuitry, that the second connection event conflicts with the first connection event schedule; identifying, by the processing circuitry, an amount of connection event timing slack corresponding to the first communication link; and adjusting, by the processing circuitry, the first connection event schedule to initiate the third connection event within the amount of connection event timing slack corresponding to the first communication link, allowing the first device to respond to the fourth connection event without conflicting with the first connection event schedule.

[0176] Clause 18. The method of clause 17, wherein identifying the amount of connection event timing slack comprises: determining, by the processing circuitry, an accuracy corresponding to the first communication link, the accuracy indicating how closely an actual frequency and an actual phase of a sequence of connection events corresponding to the first communication link match an intended frequency and an intended phase of the sequence of connection events; determining, by the processing circuitry, an uncertainty corresponding to the first communication link, the uncertainty indicating an unpredictability in a time occurrence of the sequence of connection events via the first communication link; and determining, by the processing circuitry, the connection event timing slack based on the accuracy and the uncertainty.

[0177] Clause 19. The method of any of clauses 11-18, further comprising adjusting, by the processing circuitry, the first connection event schedule so that each connection event of a set of connection events initiated by the third device following the fourth connection event do not conflict with the first connection event schedule.

[0178] Clause 20. A non-transitory computer-readable medium comprising instructions for causing one or more processors of a first device to: initiate, via a firstcommunication link, a first connection event with a second device according to a first connection event schedule; respond, via a second communication link, to a second connection event initiated by a third device according to a second connection event schedule; determine whether the second connection event conflicts with the first connection event schedule; and initiate, based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

[0179] The techniques described in this disclosure may be implemented, at least in part, in hardware, software, firmware, or any combination thereof. For example, various aspects of the techniques may be implemented within one or more microprocessors, DSPs, ASICs, FPGAs, or any other equivalent integrated or discrete logic circuitry, as well as any combinations of such components, embodied in external devices, such as physician or patient programmers, stimulators, or other devices. The terms “processor” and “processing circuitry” may generally refer to any of the foregoing logic circuitry, alone or in combination with other logic circuitry, or any other equivalent circuitry, and alone or in combination with other digital or analog circuitry.

[0180] For aspects implemented in software, at least some of the functionality ascribed to the systems and devices described in this disclosure may be embodied as instructions on a computer-readable storage medium such as RAM, DRAM, SRAM, magnetic discs, optical discs, flash memories, or forms of EPROM or EEPROM. The instructions may be executed to support one or more aspects of the functionality described in this disclosure.

[0181] In addition, in some aspects, the functionality described herein may be provided within dedicated hardware and / or software modules. Depiction of different features as modules or units is intended to highlight different functional aspects and does not necessarily imply that such modules or units must be realized by separate hardware or software components. Rather, functionality associated with one or more modules or units may be performed by separate hardware or software components or integrated within common or separate hardware or software components. Also, the techniques could be fully implemented in one or more circuits or logic elements. The techniques of this disclosure may be implemented in a wide variety of devices or apparatuses, including an IMD, anexternal programmer, a combination of an IMD and external programmer, an integrated circuit (IC) or a set of ICs, and / or discrete electrical circuitry, residing in an IMD and / or external programmer.

Claims

CLAIMSWhat is claimed is:

1. A first device comprising: a memory; and processing circuitry in communication with the memory, wherein the processing circuitry is configured to: initiate, via a first communication link, a first connection event with a second device according to a first connection event schedule; respond, via a second communication link, to a second connection event initiated by a third device according to a second connection event schedule; determine whether the second connection event conflicts with the first connection event schedule; and initiate, based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

2. The first device of claim 1, wherein the first device represents a central device according to the first communication link and the second device represents a peripheral device according to the first communication link, wherein the first device represents a peripheral device according to the second communication link and the third device represents a central device according to the second communication link, wherein the central device according to the first communication link is configured to control the first connection event schedule, and wherein the central device according to the second communication link is configured to control the second connection event schedule.

3. The first device of any of claims 1-2, wherein the processing circuitry is further configured to respond to the fourth connection event initiated by the third device according to the second connection event schedule, wherein the fourth connection event does not conflict with the first connection event schedule.

4. The first device of any of claims 1-3, wherein the first connection event schedule corresponding to the first communication link comprises a schedule for initiating each connection event of a sequence of connection events corresponding to the first communication link, the sequence of connection events including the first connection event and the third connection event, wherein a target time window of a sequence of target time windows follows each connection event of the sequence of connection events, and wherein to determine whether the second connection event conflicts with the first connection event schedule, the processing circuitry is configured to determine whether the second connection event occurs within the target time window following the first connection event.

5. The first device of claim 4, wherein based on determining that the second connection event occurs within the target time window, the processing circuitry is configured to initiate the third connection event at a planned connection event initiation time according to the first connection event schedule, and wherein based on determining that the second connection event occurs outside of the target time window, the processing circuitry is configured to adjust the first connection event schedule to initiate the third connection event at an adjusted connection event initiation time different from the planned connection event initiation time.

6. The first device of claim 5, wherein based on determining that the second connection event occurs before the target time window, the processing circuitry is configured to initiate the third connectionevent at the adjusted connection event initiation time occurring before the planned connection event initiation time, and wherein based on determining that the second connection event occurs after the target time window, the processing circuitry is configured to initiate the third connection event at the adjusted connection event initiation time occurring after the planned connection event initiation time.

7. The first device of any of claims 1-6, wherein the processing circuitry is further configured to: determine that the second connection event conflicts with the first connection event schedule; identify an amount of connection event timing slack corresponding to the first communication link; and adjust the first connection event schedule to initiate the third connection event within the amount of connection event timing slack corresponding to the first communication link, allowing the first device to respond to the fourth connection event without conflicting with the first connection event schedule.

8. The first device of claim 7, wherein to identify the amount of connection event timing slack, the processing circuitry is configured to: determine an accuracy corresponding to the first communication link, the accuracy indicating how closely an actual frequency and an actual phase of a sequence of connection events corresponding to the first communication link match an intended frequency and an intended phase of the sequence of connection events; determine an uncertainty corresponding to the first communication link, the uncertainty indicating an unpredictability in a time occurrence of the sequence of connection events via the first communication link; and determine the connection event timing slack based on the accuracy and the uncertainty.

9. The first device of any of claims 1-8, wherein the processing circuitry is further configured to adjust the first connection event schedule so that each connection event of aset of connection events initiated by the third device following the fourth connection event do not conflict with the first connection event schedule.

10. The first device of any of claims 1-9, wherein the first device comprises a first external device, wherein the second device comprises a medical device configured to be implanted underneath a skin of a patient, and the third device comprises a second external device.

11. A method comprising : initiating, by processing circuitry of a first device via a first communication link, a first connection event with a second device according to a first connection event schedule, wherein the processing circuitry is in communication with a memory; responding, by the processing circuitry via a second communication link, to a second connection event initiated by a third device according to a second connection event schedule; determining, by the processing circuitry, whether the second connection event conflicts with the first connection event schedule; and initiating, by the processing circuitry based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourth connection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

12. The method of claim 11, wherein the first device represents a central device according to the first communication link and the second device represents a peripheral device according to the first communication link, wherein the first device represents a peripheral device according to the second communication link and the third device represents a central device according to the second communication link, wherein the central device according to the first communication link is configured to control the first connection event schedule, andwherein the central device according to the second communication link is configured to control the second connection event schedule.

13. The method of any of claims 11-12, further comprising responding, by the processing circuitry to the fourth connection event initiated by the third device according to the second connection event schedule, wherein the fourth connection event does not conflict with the first connection event schedule.

14. The method of any of claims 11-13, wherein the first connection event schedule corresponding to the first communication link comprises a schedule for initiating each connection event of a sequence of connection events corresponding to the first communication link, the sequence of connection events including the first connection event and the third connection event, wherein a target time window of a sequence of target time windows follows each connection event of the sequence of connection events, and wherein determining whether the second connection event conflicts with the first connection event schedule comprises determining, by the processing circuitry, whether the second connection event occurs within the target time window following the first connection event.

15. A non-transitory computer-readable medium comprising instructions for causing one or more processors of a first device to: initiate, via a first communication link, a first connection event with a second device according to a first connection event schedule; respond, via a second communication link, to a second connection event initiated by a third device according to a second connection event schedule; determine whether the second connection event conflicts with the first connection event schedule; and initiate, based on whether the second connection event conflicts with the first connection event schedule, a third connection event with the second device so that a fourthconnection event initiated by the third device according to the second connection event schedule does not conflict with the first connection event schedule.

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