Crosstalk protection for multi-chamber leadless pacemaker systems

Abstract

A dual-chamber leadless pacemaker (LP) system includes a first leadless pacemaker (LP1) and a second leadless pacemaker (LP2), wherein LP1 is configured to be implanted in or on a first heart chamber and deliver pacing pulses to the first heart chamber, and LP2 is configured to be implanted in or on a second heart chamber and deliver pacing pulses to the second heart chamber. Information is obtained regarding the amplitude of the pacing pulses delivered by LP2 to the second heart chamber and / or the sensitivity of a sensing circuit of LP1, which is configured to be used by LP1 to detect the inherent depolarization of the first heart chamber. A crosstalk protection duration is determined based on at least some of this information, such that it is performed for an appropriate duration when crosstalk protection is executed.

Description

[0001] Priority requirements

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 591,717, filed October 19, 2023, which is incorporated herein by reference as if its entire contents were fully set forth herein. Technical Field

[0003] The embodiments described herein generally relate to leadless pacemakers (LP), multi-chamber leadless pacemaker (LP) systems, methods of using them, and non-implantable programmers used therewith. Background Technology

[0004] A conventional pacemaker typically includes a housing (also called a "canister") that houses the controller (e.g., a processor), and one or more intravascular leads extending from the housing. Each lead includes one or more electrodes for sensing cardiac electrical activity and for delivering pacing stimulation. Such conventional pacemakers can support single-chamber operating modes (e.g., VVI, AAI) and dual-chamber operating modes (e.g., DDD, VDD), depending on the number of leads used and how the conventional pacemaker is programmed.

[0005] In recent years, physicians have begun implanting leadless pacemakers (LPs) to replace traditional pacemakers that require additional electrical leads. This is beneficial because such leads can fail and / or migrate more frequently than expected. Early LPs were implanted as stand-alone devices in a single heart chamber (e.g., the right ventricle (RV) chamber) and thus supported single-chamber operating modes (e.g., WVI). It is now expected that multiple LPs will be implanted and optionally coordinated in one or more heart chambers (e.g., in the RV chamber and the right atrium (RA) chamber) to provide dual-chamber LP systems capable of supporting dual-chamber operating modes (e.g., DDD, VDD). More generally, there is a trend toward implanting two LPs in (or above) two or more heart chambers to provide multi-chamber pacing.

[0006] Traditional pacemakers include a central processing unit (CPU) that uses separate leads for each of the multiple cardiac chambers (e.g., one lead for the right atrium and another for the right ventricle) to manage cardiac activity in multiple chambers of the patient's heart. This allows the conventional pacemaker to sense the inherent activity in multiple cardiac chambers and provide pacing support accordingly, as well as maintain atrioventricular (AV) synchronization. This conventional pacemaker configuration also has the significant advantage of providing inherent protection against crosstalk, which occurs when a pacing pulse delivered by one lead and electrode combination is inappropriately detected as inherent myocardial depolarization by different lead and electrode combinations (e.g., located in different chambers of the heart). Because the conventional pacemaker provides pacing stimulation, it can also coordinate when and for how long to blank or ignore sensing signals from all other lead and electrode combinations, thereby mitigating the risk of crosstalk adversely affecting the operation of the conventional pacemaker. However, leadless pacemakers (LPs) do not possess this inherent common sense, because each LP implanted in (or on) a different heart chamber is an independent device with its own controller (e.g., CPU). Therefore, a coordinated LP system relies on some form of wireless communication to synchronize with another LP and otherwise exchange information. Summary of the Invention

[0007] Some embodiments of this technology relate to a system for use with or including a first leadless pacemaker (LP 1) and a second leadless pacemaker (LP 2), wherein LP 1 is configured to be implanted in or on a first heart chamber of a patient's heart and deliver pacing pulses to the first heart chamber, and LP 2 is configured to be implanted in or on a second heart chamber of the patient's heart and deliver pacing pulses to the second heart chamber. The system includes a controller configured to acquire information about one or more of the following: the amplitude of the pacing pulses delivered to the second heart chamber by LP 2; or the sensitivity of a sensing circuit of LP 1 configured to be used by LP 1 to detect inherent depolarization of the first heart chamber. The controller is also configured to determine the crosstalk protection duration based on at least some information, wherein the determined crosstalk protection duration is used by LP 1 to perform crosstalk protection during the crosstalk protection duration in response to LP 1 detecting possible crosstalk that may be caused by one of the pacing pulses transmitted by LP 2.

[0008] According to some embodiments, the controller is configured to obtain information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second cardiac chamber; and to determine a crosstalk protection duration based on the amplitude of the pacing pulse, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration. In an embodiment, when the controller is configured to determine the crosstalk protection duration based on the amplitude of the pacing pulse such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, the controller is configured to: if the pacing pulse has a first amplitude, determine that the crosstalk duration has a first duration, and if the pacing pulse has a second amplitude greater than the first amplitude, determine that the crosstalk duration has a second duration longer than the first duration. The controller can also be configured to: if the pacing pulse has a third amplitude less than the first amplitude, determine that the crosstalk duration has a third duration shorter than the first duration.

[0009] According to some embodiments, the controller is configured to obtain information about the amplitude of the pacing pulse configured to be transmitted to the second heart chamber by acquiring information about at least one of the pulse amplitude or pulse width of the pacing pulse configured to be transmitted to the second heart chamber.

[0010] According to some embodiments, the controller is configured to obtain information about the sensitivity of the sensing circuitry of LP1. In some such embodiments, the sensitivity of the sensing circuitry of LP1 is specified by a sensing detection threshold of the sensing circuitry of LP1, which is configured to be used by LP1 to detect the inherent depolarization of the first cardiac chamber, and the controller is configured to determine a crosstalk protection duration based on the sensing detection threshold of the sensing circuitry, such that there is a negative correlation between the sensing detection threshold of the sensing circuitry and the crosstalk protection duration. In one embodiment, wherein the controller is configured to determine the crosstalk protection duration based on the sensing detection threshold of the sensing circuitry of LP1, such that there is a negative correlation between the sensing detection threshold of the sensing circuitry of LP1 and the crosstalk protection duration, the controller is configured to: determine that the crosstalk duration has a first duration if the sensing detection threshold of the sensing circuitry of LP1 has a first amplitude, and determine that the crosstalk duration has a second duration shorter than the first duration if the sensing detection threshold of the sensing circuitry of LP1 has a second amplitude greater than the first amplitude. Such a controller can also be configured to determine that the crosstalk duration has a third duration longer than the first duration if the sensing detection threshold of the sensing circuit of LP 1 has a third amplitude less than the first amplitude. Alternatively, the sensitivity of the sensing circuit of LP 1 is specified by the gain of the sensing circuit of LP 1, which is configured to be used by LP 1 to detect the inherent depolarization of the first cardiac chamber, and the controller is configured to determine the crosstalk protection duration based on the gain of the sensing circuit, such that there is a positive correlation between the gain of the sensing circuit and the crosstalk protection duration. In one embodiment, when the controller is configured to determine the crosstalk protection duration based on the gain of the sensing circuit of LP 1 (which is configured to detect the inherent depolarization of the first cardiac chamber), such that there is a positive correlation between the gain of the sensing circuit (which is configured to detect the inherent depolarization of the first cardiac chamber) and the crosstalk protection duration, the controller is configured to determine that the crosstalk protection duration has a first duration if the gain circuit has a first gain, and to determine that the crosstalk protection duration has a second duration longer than the first duration if the gain circuit has a second gain greater than the first gain. If the gain circuit has a third gain that is less than the first gain, such a controller can also be configured to determine that the crosstalk duration has a third duration that is shorter than the first duration.

[0011] According to some embodiments, the controller is configured to obtain information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, and to obtain information about the sensitivity of a sensing circuit of LP 1, which is configured by LP 1 to detect the inherent depolarization of the first heart chamber; and to determine the duration of crosstalk protection based on the amplitude of the pacing pulse and the sensitivity of the sensing circuit.

[0012] According to some embodiments, the controller is configured to further determine the crosstalk protection duration based on at least one associated scaling factor of the distance between LP1 and LP2 or the angles of LP1 and LP2 relative to each other. In some such embodiments, the controller is configured to: determine the initial crosstalk protection duration based on at least some information; determine the scaling factor based on the distance between LP1 and LP2 or the angles of LP1 and LP2 relative to each other; and determine the crosstalk protection duration by scaling the initial crosstalk protection duration with the scaling factor.

[0013] According to some embodiments, the system includes a portion of LP 1 containing a controller, wherein the controller of LP 1 is configured to monitor and detect possible crosstalk that may be caused by LP 2 delivering one of the pacing pulses; and in response to detecting possible crosstalk that may be caused by LP 2 delivering one of the pacing pulses, to initiate the execution of crosstalk protection for the duration of crosstalk protection.

[0014] According to some embodiments, the controller of LP 1 is configured to: dynamically adjust the sensitivity of the sensing circuit of LP 1; and determine the crosstalk protection duration based on the sensitivity, such that when the controller of LP 1 adjusts the sensitivity of the sensing circuit of LP 1, the controller of LP 1 updates the crosstalk protection duration.

[0015] According to some embodiments, the controller of LP2 is configured to dynamically adjust the amplitude of the pacing pulse that LP2 is configured to deliver to the second heart chamber, and notify the controller of LP1 of the adjustment to the amplitude of the pacing pulse; and the controller of LP1 is configured to determine the crosstalk protection duration based on the amplitude of the pacing pulse that LP2 is configured to deliver to the second heart chamber, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, and such that in response to the controller of LP1 being notified of the adjustment to the amplitude of the pacing pulse, the controller of LP1 updates the crosstalk protection duration.

[0016] According to some embodiments, the system includes a non-implantable programmer that includes a controller (configured to determine the crosstalk protection duration) and is configured to communicate with LP1 and LP2 (directly or through an intermediary such as another IMD), wherein the non-implantable programmer is configured to program the crosstalk protection duration into the memory or one or more registers of LP1 such that the crosstalk protection duration is available to LP1 when LP1 detects possible crosstalk that may be caused by one of the pacing pulses transmitted by LP2.

[0017] According to some embodiments, the system includes a portion of LP 1 containing a controller, wherein the controller of LP 1 is configured to provide crosstalk protection during the crosstalk protection duration by causing at least one of the following: blanking the sensing circuitry of LP 1 during the crosstalk protection duration; ignoring any possible inherent depolarization detected by the sensing circuitry of LP 1 during the crosstalk protection duration; disabling the sensing circuitry of LP 1 during the crosstalk protection duration; ignoring any interruptions generated by the sensing circuitry in response to detecting possible inherent depolarization during the crosstalk protection duration; and disabling the generation of interruptions that may be generated in response to the sensing circuitry detecting inherent depolarization during the crosstalk protection duration. More generally, during the crosstalk protection duration associated with LP 1, LP 1 (more specifically, its controller) is prevented from detecting and / or ignores the detection of any possible inherent depolarization.

[0018] According to some embodiments, the system includes a portion of LP 1 containing a controller, and the controller of LP 1 is configured to determine whether the detected possible crosstalk is part of a valid message sent by another device; and in response to determining that the detected possible crosstalk is part of a valid message sent by another device, terminate crosstalk protection for the remainder of the crosstalk protection duration.

[0019] Some embodiments of this technology relate to a leadless pacemaker configured to communicate with another leadless pacemaker, wherein the leadless pacemaker is configured to be implanted in or on a first heart chamber of a patient's heart and to deliver pacing pulses to the first heart chamber, and the other leadless pacemaker is configured to be implanted in or on a second heart chamber of the patient's heart and to deliver pacing pulses to the second heart chamber. The leadless pacemaker includes sensing circuitry and a controller. The sensing circuitry is configured to detect inherent depolarization of the first heart chamber. The controller is configured to obtain information about one or more of the following: the amplitude of the pacing pulses delivered by the other leadless pacemaker to the second heart chamber, or the sensitivity of the sensing circuitry. The controller is also configured to: determine a crosstalk protection duration based on at least some information; monitor for possible crosstalk that may be caused by the other leadless pacemaker delivering one of the pacing pulses; and, in response to detecting possible crosstalk that may be caused by the other leadless pacemaker delivering one of the pacing pulses, perform crosstalk protection during the crosstalk protection duration.

[0020] According to some embodiments, the controller is configured to obtain information about the amplitude of a pacing pulse that is configured to be delivered to a second heart chamber by another leadless pacemaker, and based on this, to determine a crosstalk protection duration such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration.

[0021] According to some embodiments, the controller is configured to obtain information about a sensing detection threshold of the sensing circuit and determine a crosstalk protection duration based on the sensing detection threshold of the sensing circuit, such that there is a negative correlation between the sensing detection threshold of the sensing circuit and the crosstalk protection duration; or to obtain information about the gain of the sensing circuit and determine the crosstalk protection duration based on the gain of the sensing circuit, such that there is a positive correlation between the gain of the sensing circuit and the crosstalk protection duration.

[0022] According to some embodiments, the controller is configured to obtain information about the amplitude of a pacing pulse that is configured to be delivered to a second heart chamber by another leadless pacemaker; obtain information about the sensitivity of the sensing circuit; and determine the duration of crosstalk protection based on the amplitude of the pacing pulse and the sensitivity of the sensing circuit.

[0023] According to some embodiments, the controller is configured to further determine the crosstalk protection duration based on at least one associated scaling factor of the distance between the leadless pacemaker and another leadless pacemaker or the angle between the leadless pacemaker and another leadless pacemaker relative to each other. In some such embodiments, the controller is configured to: determine the initial crosstalk protection duration based on at least some information; determine the scaling factor based on the distance between LP1 and LP2 or the angle between LP1 and LP2 relative to each other; and determine the crosstalk protection duration by scaling the initial crosstalk protection duration with the scaling factor.

[0024] According to some embodiments, the controller is configured to dynamically adjust the sensitivity of the sensing circuit; and to determine the crosstalk protection duration based on the sensitivity of the sensing circuit, such that the crosstalk protection duration is updated when the sensitivity of the sensing circuit is adjusted.

[0025] According to some embodiments, the controller is configured to determine the crosstalk protection duration based on the amplitude of the pacing pulse of another leadless pacemaker configured to be delivered to the second heart chamber, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, and such that the crosstalk protection duration is updated in response to being informed of adjustments made to the amplitude of the pacing pulse of another leadless pacemaker configured to be delivered to the second heart chamber.

[0026] According to some embodiments, the controller is configured to provide crosstalk protection during the crosstalk protection duration by causing at least one of the following: blanking the sensing circuit during the crosstalk protection duration; ignoring any possible inherent depolarization detected by the sensing circuit during the crosstalk protection duration; disabling the sensing circuit during the crosstalk protection duration; ignoring any interruption generated by the sensing circuit in response to detecting a possible inherent depolarization during the crosstalk protection duration; or preventing the generation of interruptions that could be generated in response to the sensing circuit detecting inherent depolarization during the crosstalk protection duration. More generally, during the crosstalk protection duration associated with the LP, the LP (more specifically, its controller) is prevented from detecting and / or ignoring the detection of any possible inherent depolarization.

[0027] According to some embodiments, the controller is configured to determine whether the detected potential crosstalk is part of a valid message sent by another device; and in response to determining that the detected potential crosstalk is part of a valid message sent by another device, terminate the crosstalk protection for the remaining time of the crosstalk protection duration.

[0028] Some embodiments of this technology relate to a crosstalk protection method for a dual-chamber leadless pacemaker (LP) system, the system including a first leadless pacemaker (LP 1) and a second leadless pacemaker (LP 2), wherein LP 1 is configured to be implanted in or onto a first cardiac chamber of a patient's heart and to deliver pacing pulses to the first cardiac chamber, and LP 2 is configured to be implanted in or onto a second cardiac chamber of the patient's heart and to deliver pacing pulses to the second cardiac chamber. The method includes obtaining information about one or more of the following: the amplitude of the pacing pulses that LP 2 is configured to deliver to the second cardiac chamber; or the sensitivity of a sensing circuit of LP 1, the sensing circuit being configured to be used by LP 1 to detect inherent depolarization of the first cardiac chamber. The method also includes determining the duration of crosstalk protection based on at least some of this information. The method further includes: LP 1 monitoring and detecting possible crosstalk that may be caused by one of the pacing pulses delivered by LP 2; and LP 1 initiating crosstalk protection for the duration of crosstalk protection in response to detecting possible crosstalk that may be caused by LP 2 delivering one of the pacing pulses.

[0029] According to some embodiments, obtaining information includes obtaining information about the amplitude of the pacing pulse that LP2 is configured to deliver to the second heart chamber; and determining the crosstalk protection duration based on the amplitude of the pacing pulse, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration. According to some embodiments, obtaining information about the amplitude of the pacing pulse that LP2 is configured to deliver to the second heart chamber includes obtaining information about at least one of the pulse amplitude or pulse width of the pacing pulse that LP2 is configured to deliver to the second heart chamber.

[0030] According to some embodiments, obtaining information includes obtaining information about the sensitivity of the sensing circuitry of LP1. In some such embodiments, the sensitivity of the sensing circuitry of LP1 is specified by a sensing detection threshold of the sensing circuitry of LP1, which is configured to be used by LP1 to detect the inherent depolarization of the first cardiac chamber, and the crosstalk protection duration is determined based on the sensing detection threshold of the sensing circuitry such that there is a negative correlation between the sensing detection threshold of the sensing circuitry and the crosstalk protection duration. Alternatively, the sensitivity of the sensing circuitry of LP1 is specified by the gain of the sensing circuitry of LP1, which is configured to be used by LP1 to detect the inherent depolarization of the first cardiac chamber, and the crosstalk protection duration is determined based on the gain of the sensing circuitry such that there is a positive correlation between the gain of the sensing circuitry and the crosstalk protection duration.

[0031] According to some embodiments, the information obtained includes obtaining information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, and obtaining information about the sensitivity of the sensing circuit of LP 1, which is configured to be used by LP 1 to detect the inherent depolarization of the first heart chamber; and determining the crosstalk protection duration based on the amplitude of the pacing pulse and the sensitivity of the sensing circuit.

[0032] According to some embodiments, determining the crosstalk protection duration is further based on at least one of a scaling factor associated with the distance between LP1 and LP2 or the angle between LP1 and LP2 relative to each other. In some such embodiments, determining the crosstalk protection duration based on the scaling factor includes: determining an initial crosstalk protection duration based on at least some information; determining a scaling factor based on the distance between LP1 and LP2 or the angle between LP1 and LP2 relative to each other; and determining the crosstalk protection duration by scaling the initial crosstalk protection duration with the scaling factor.

[0033] According to some embodiments, the determination of the crosstalk protection duration is performed by the controller of LP 1.

[0034] According to some embodiments, the controller of LP 1 is configured to dynamically adjust the sensitivity of the sensing circuit of LP 1; and to determine the crosstalk protection duration based on the sensitivity, such that when the controller of LP 1 adjusts the sensitivity of the sensing circuit of LP 1, the controller of LP 1 updates the crosstalk protection duration.

[0035] According to some embodiments, the controller of LP 2 is configured to dynamically adjust the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, and notify the controller of LP 1 of the adjustment to the amplitude of the pacing pulse; and determine the crosstalk protection duration based on the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, and such that the controller of LP 1 updates the crosstalk protection duration in response to the controller of LP 1 being notified by LP 2 of the adjustment to the amplitude of the pacing pulse.

[0036] According to some embodiments, obtaining the information and determining the crosstalk protection duration are performed by a non-implantable programmer; and the method further includes the non-implantable programmer programming the crosstalk protection duration into the memory or one or more registers of the LP 1 such that the crosstalk protection duration is available to the LP 1 when the LP 1 detects possible crosstalk (which may be caused by one of the pacing pulses delivered by the LP 2).

[0037] According to some embodiments, providing crosstalk protection during the crosstalk protection duration includes at least one of the following: blanking the sensing circuit of LP 1 during the crosstalk protection duration; ignoring any possible inherent depolarization detected by the sensing circuit of LP 1 during the crosstalk protection duration; disabling the sensing circuit of LP 1 during the crosstalk protection duration; ignoring any interruptions generated by the sensing circuit in response to detecting possible inherent depolarization during the crosstalk protection duration; or disabling the generation of interruptions that may be generated in response to the sensing circuit detecting inherent depolarization during the crosstalk protection duration. More generally, during the crosstalk protection duration, detection and / or ignoring of possible inherent depolarization are prevented.

[0038] According to some embodiments, the method further includes determining that the detected potential crosstalk is part of a valid message sent by another device, and in response, terminating the crosstalk protection for the remainder of the crosstalk protection duration.

[0039] This invention is not intended to be a complete description of embodiments of the present technology. Other features and advantages of embodiments of the present technology will become apparent from the following description, in which preferred embodiments have been set forth in detail with reference to the accompanying drawings and claims. Attached Figure Description

[0040] Embodiments of the present technology relating to both the structure and the method of operation can be best understood by referring to the following description and accompanying drawings, wherein similar reference numerals denote similar elements in several views:

[0041] Figure 1 A system for implantation in the heart, formed according to certain embodiments herein, is shown.

[0042] Figure 2 This is a block diagram of a single LP according to some embodiments herein.

[0043] Figure 3 The LP is described according to certain embodiments described herein.

[0044] Figure 4 This is a timing diagram illustrating one embodiment of i2i communication used for pacing events.

[0045] Figure 5 This is a timing diagram illustrating one embodiment of i2i communication used for sensing events.

[0046] Figure 6 It is a timing diagram used to illustrate how pacing pulses delivered by a second LP implanted in (or on) a remote heart chamber can cause crosstalk that may be incorrectly detected by a first LP implanted in (or on) a local heart chamber as an inherent depolarization of the local heart chamber.

[0047] Figures 7A and 7B are high-level flowcharts for outlining methods according to certain embodiments of the present technology.

[0048] Figure 8 A block diagram of one embodiment of an IMD (e.g., LP) implanted in a patient as part of an implantable cardiac system, according to certain embodiments of this document, is shown.

[0049] Figure 9 A block diagram of one embodiment of an external device 109 is shown, the external device 109 being used to interact with... Figure 1 The LP and / or ICD or some types of implantable medical devices (IMDs) described herein communicate with and / or program to them, and can be used to implement certain embodiments of this technology. Detailed Implementation

[0050] As described above, it is now desirable to implant LPs in two or more cardiac chambers, such as the RV chamber and the RA chamber, to provide a multi-chamber (e.g., dual-chamber) LP system capable of supporting dual-chamber operating modes (e.g., DDD, VDD) or more generally multi-chamber operating modes. An LP implanted in (or on) the RV chamber, or configured to be implanted in (or on) the RV chamber, may herein be referred to as a ventricular LP or vLP. An LP implanted in (or on) the RA chamber, or configured to be implanted in (or on) the RA chamber, may herein be referred to as an atrial LP or aLP.

[0051] When more than one pacing pulse (LP) is implanted in and / or on a patient's heart, there is a risk that a pacing pulse delivered by one LP may be detected by the sensing circuitry of another LP and incorrectly interpreted as an inherent activation event. In other words, there is a risk that an LP implanted in or on the first ventricle of the heart may detect and interpret crosstalk caused by pacing of the second ventricle by another LP implanted in or on the second ventricle as an inherent event of the first ventricle (also known as inherent depolarization).

[0052] When implant-to-implant (i2i) communication between LPs is enabled and functioning correctly, an LP can send an i2i message (and more specifically, a pacing event i2i message) immediately before delivering a pacing pulse. In this case, the i2i message warns the other LP of an impending pacing pulse, allowing the other LP to preemptively blank its sensing circuitry and prevent inappropriate crosstalk detection. However, when i2i communication in a multi-chamber LP system is unsuccessful, blocked, or disabled, there is a real risk that crosstalk (caused by one of the LPs delivering the pacing pulse) may be detected by (the other LP) and adversely affect the operation of the multi-chamber LP system. For example, in cases where crosstalk is unintentionally interpreted as a sensed intrinsic cardiac event (also known as sensed intrinsic depolarization), pacing of a cardiac chamber may be suppressed when it should actually be delivered, and / or the timing of one or more further pacing pulses may be adversely affected.

[0053] To mitigate (and preferably prevent) the adverse effects of crosstalk on a dual-chamber LP system (or more generally, a multi-chamber LP system), each LP in the system can independently monitor for potential crosstalk that may be caused by another LP delivering pacing pulses. Then, in response to the detection of potential crosstalk, the LP that detected it can perform crosstalk protection for a period of time (also known as duration), where crosstalk protection may involve, for example, blanking a sensing circuit used by the LP to monitor inherent events in the chamber in which (or on) the LP is implanted. Alternatively, or additionally, crosstalk protection (performed in response to the detection of potential crosstalk) may include ignoring any potential inherent depolarization detected by the sensing circuit of the LP during the duration, disabling the sensing circuit of the LP during the duration, ignoring any interruptions (generated in response to the sensing circuit detecting potential inherent depolarization) during the duration, or disabling interruptions (possibly generated in response to the sensing circuit detecting inherent depolarization) during the duration, but is not limited to these. Such crosstalk protection can be performed under the assumption that any potential inherent depolarization detected when crosstalk protection is performed is actually caused by crosstalk. More generally, during the crosstalk protection duration, it prevents the detection and / or ignores any possible inherent depolarization.

[0054] LPs can use various techniques to detect potential crosstalk that may be caused by another LP, some of which are described below. However, detecting potential crosstalk alone does not mitigate the potential adverse effects of potential crosstalk, as it is also beneficial to determine the duration of crosstalk protection. In other words, while detecting potential crosstalk is beneficial, determining the duration of crosstalk protection is also beneficial, where the duration of crosstalk protection can correspond to how long the sensing circuit (for sensing local inherent depolarization) should blank upon detecting potential crosstalk, or more generally, how long crosstalk protection should be performed upon detecting potential crosstalk.

[0055] Determining the appropriate crosstalk protection duration for use in a two-chamber LP system (and more generally, a multi-chamber LP system) is no trivial task, as various factors can influence the appropriate crosstalk protection duration for an LP system. If the crosstalk protection duration is set too short, it may result in residual detection of crosstalk that could be incorrectly detected as inherent depolarization. Conversely, if the crosstalk protection duration is set too long, it may result in genuine local inherent events being missed (i.e., undetected).

[0056] Some embodiments of this technology relate to systems, subsystems, and methods for specifying and utilizing appropriate crosstalk protection durations for the LP of a multi-chamber LP system. Figures 1-5An example dual-chamber LP system is described, which may optionally also include a non-vascular ICD (NV-ICD) (such as a subcutaneous ICD (S-ICD)) and an external device (such as a programmer).

[0057] Figure 1 A system 100 is shown comprising LPs 102a and 102b located in different chambers of the heart 101. LP 102a is located in the right atrium and is therefore also referred to herein as an atrial LP (aLP). LP 102b is located in the right ventricle and is therefore also referred to herein as a ventricular LP (vLP). aLP 102a and vLP 102b may be collectively referred to herein as LP102, or individually as LP 102. Therefore, when referring to LP 102 in general, LP 102 may be LP 102a or LP 102b. LPs 102a and 102b can communicate with each other to notify each other of various local physiological activities, such as local intrinsic events, local pacing events, etc. LPs 102a and 102b may be constructed in a similar manner, but operate differently depending on which chamber LP 102a or 102b is located in.

[0058] In some embodiments, LPs 102a and 102b communicate with each other and / or with ICD 106 via conductive communication through the same electrodes used for sensing and / or delivering pacing therapy. LPs 102a and 102b are also capable of using conductive communication to communicate with an external device (e.g., programmer 109) having electrodes placed on the skin of a patient to which LPs 102a and 102b are implanted. LPs 102a and 102b may each alternatively or additionally include an antenna that would enable them to communicate with each other and with ICD 106 and / or external device 109 using RF communication. Alternatively or additionally, LPs 102a and 102b may utilize another type of communication, such as inductive communication, in which case LPs 102a and 102b may each include a corresponding inductive communication coil. Alternatively or additionally, LPs 102 a and 102 b may use conducted communication when communicating with each other, and another type of communication (such as RF communication or inductive communication) when communicating with external device 109 (such as a programmer). Although Figure 1 Only two LPs are shown in the figure, but more than two LPs can be implanted in a patient. For example, in order to provide biventricular pacing and / or cardiac resynchronization therapy (CRT), in addition to implanting LPs in the right atrium (RA) chamber and the right ventricle (RV) chamber, an additional LP can be implanted in the left ventricle (LV) chamber.

[0059] Each LP 102 uses two or more electrodes located within, above, or a few centimeters of the LP's housing for pacing and sensing in the heart chambers. Where the LP 102 communicates using conductive communication, the electrodes of the LP 102 can also be used for bidirectional conductive communication with each other and with the programmer 109 and ICD 106. Note that the terms conductive communication and conductive communication are used interchangeably herein.

[0060] refer to Figure 2 The block diagram illustrates embodiments of the electronics within LPs 102a and 102b, configured to provide conductive communication via sensing / pacing electrodes. One or more of LPs 102a and 102b include at least two leadless electrodes configured to deliver cardiac pacing pulses, sense induced and / or natural cardiac electrical signals, and provide unidirectional or bidirectional conductive communication. Figure 2 (and Figure 3 In the diagram, the two electrodes shown are labeled 108a and 108B. Such electrodes may be collectively referred to as electrode 108, or individually as electrode 108. Depending on the implementation, LP 102 or other types of IMD may include more than two electrodes 108.

[0061] exist Figure 2 In the diagram, each of LP 102 A and 102 b is shown as including a first receiver 120 and a second receiver 122, which together define a separate first conductive communication channel 105 and a second conductive communication channel 107 between LP 102 A and 102 b. Figure 1 (etc.). Although a first receiver 120 and a second receiver 122 are depicted, in other embodiments, each LP 102a, 102b may include only the first receiver 120, or more generally may include only a single receiver configured to receive conducted communication signals. LP 102 may also include additional receivers in addition to the first receiver 120 and the second receiver 122. As will be described in further detail below, the pulse generator 116 may be used as a transmitter to transmit i2i communication signals using the electrode 108. In some embodiments, LP 102a and 102b may communicate not only through the first conductive communication channel 105 and the second conductive communication channel 107. In some embodiments, LP 102a and 102b may communicate through a common communication channel 105. More specifically, LP 102a and 102b may communicate conductively on a common physical channel via the same electrode 108, which is also used to deliver pacing pulses.

[0062] Receivers 120 and 122 can also be referred to as a low-frequency (LF) receiver 120 and a high-frequency (HF) receiver 122, respectively, because receiver 120 is configured to monitor one or more signals in a relatively low frequency range (e.g., below 100 kHz), and receiver 122 is configured to monitor one or more signals in a relatively high frequency range (e.g., above 100 kHz). In some embodiments, receiver 120 (and more specifically, at least a portion thereof) is always enabled and monitors for wake-up notifications within a specific low-frequency range (e.g., between 1 kHz and 100 kHz), which may simply be a wake-up pulse; and receiver 122 is selectively enabled by receiver 120. Receiver 120 is configured to consume less power than receiver 122 when both the first and second receivers are enabled. Therefore, receiver 120 can also be referred to as a low-power receiver 120, and receiver 122 can also be referred to as a high-power receiver 122.

[0063] According to some embodiments, the low-power receiver 120 cannot receive signals in a relatively high frequency range (e.g., above 100 kHz), but consumes significantly less power than the high-power receiver 122. Thus, the low-power receiver 120 can always monitor for wake-up notifications without significantly depleting the LP's battery (e.g., 114). According to some embodiments, in response to the low-power receiver 120 receiving a wake-up notification, the high-power receiver 122 is selectively enabled by the low-power receiver 120, allowing the high-power receiver 122 to receive signals at higher frequencies, thereby handling the higher data throughput required for effective i2i communication without unnecessarily and rapidly depleting the LP's battery (which the high-power receiver 122 might do if it were always enabled).

[0064] Since receivers 120 and 122 are used to receive conducted communication messages, they can also be referred to as conducted communication receivers. In some embodiments, each LP 102 includes only a single conducted communication receiver.

[0065] According to some embodiments, when one of LPs 102a and 102b senses an intrinsic event or delivers a pacing event, the corresponding LP 102a, 102b sends an implanted event message to the other LP 102a, 102b. For example, when LP 102a senses / paces an atrial event, LP 102a transmits an implanted event message including an event tag indicating the nature of the event (e.g., intrinsic / sensed atrial event, pacing atrial event). When vLP 102b senses / paces a ventricular event, vLP 102b sends an implanted event message including an event tag indicating the nature of the event (e.g., intrinsic / sensed ventricular event, pacing ventricular event). In some embodiments, each LP 102a, 102b sends an implanted event message to the other LP 102a, 102b before the actual pacing pulse, such that the remote LP can blank its sensing input when the remote pacing pulse is anticipated (to prevent inappropriate crosstalk sensing). The implantation event message described above is an example of an i2i message.

[0066] Implanted event messages can be formatted in various ways. As an example, each event message may include a preamble trigger pulse (also known as an LP wake-up notification, wake-up pulse, or wake-up signal) followed by an event marker. The notification trigger pulse (also known as a wake-up notification, wake-up pulse, or wake-up signal) is transmitted via a first channel (e.g., with a pulse duration of approximately 10 μs to approximately 1 ms and / or in a baseband frequency range of approximately 1 kHz to approximately 100 kHz). The notification trigger pulse indicates that the event marker will be transmitted on a second channel (e.g., in a higher frequency range). The event marker can then be transmitted via the second channel.

[0067] Event flags may include data indicating one or more events (e.g., sensed intrinsic atrial activation for aLP, sensed intrinsic ventricular activation for vLP). Event tags may include different tags for intrinsic events and pacing events. Event tags may also indicate the start or end time of a timer (e.g., AV interval, blanking interval, etc.). Optionally, the implanted event message may include a message fragment that includes additional / auxiliary information.

[0068] Optionally, an LP (or other IMD, such as an implantable cardiac monitor (ICM), subcutaneous ICD (SICD), or nonvascular ICD (NV-ICD)) receiving any i2i communication messages from another LP (or other IMD) or from an external device can send a reception acknowledgment (ACK) indicating that the receiving LP (or other IMD) has received the i2i communication message. In some embodiments, if an LP (or other IMD) expects to receive an i2i communication message within a window and fails to do so, the LP (or other IMD) can transmit a reception failure acknowledgment indicating that the receiving LP (or other IMD) has failed to receive the i2i communication message. The reception failure acknowledgment message can also be referred to as a negative acknowledgment (NACK) message. An LP can receive a message from another LP that includes an indicator (e.g., an error code) in its payload or header indicating to that LP that the other LP has failed to receive the expected message from that LP. Other variations are also possible and are within the scope of the embodiments described herein.

[0069] Event messages enable LPs 102a and 102b to deliver synchronized treatment and additional supportive features (e.g., measurements). To maintain synchronized treatment, each of LPs 102a and 102b is informed (via event messages) when an event occurs in a chamber containing the other LPs 102a and 102b. Some embodiments described herein provide efficient and reliable procedures for maintaining synchronization between LPs 102a and 102b without maintaining continuous communication between them. According to some embodiments herein, low-power event messages / signaling can be maintained synchronously or asynchronously between LPs 102a and 102b.

[0070] With synchronous event signaling, LP 102 A and 102 b can remain synchronized and communicate periodically at specific intervals. Synchronous event signaling allows the transmitters and receivers in each LP 102 a and 102 b to use limited (or minimal) power, as each LP 102 a and 102 b is powered only for a small fraction of the time associated with transmission and reception. For example, LP 102 a and 102 b can transmit / receive (Tx / Rx) communication messages in time slots with a duration of 10-20 μs, where the Tx / Rx time slots occur periodically (e.g., every 10-20 ms). This synchronous event signaling can be used, for example, when LP 102 a and 102 b jointly provide DDD operation, but is not limited to this.

[0071] Even in a synchronization event signaling scheme, LPs 102 A and 102 b may lose synchronization. As explained herein, features can be included in LPs 102 a and 102 b to maintain device synchronization, and LPs 102 a and 102 b undergo a synchronization recovery operation when synchronization is lost. Furthermore, synchronization event messages / signaling may introduce delays between transmissions, resulting in a lag in response at the receiving LPs 102 a and 102 b. Therefore, features can be implemented to account for this lag.

[0072] During asynchronous event signaling, LPs 102 A and 102 b do not maintain communication synchronization. During asynchronous event signaling, one or more of the receivers 120 and 122 of LPs 102 a and 102 b can be "always on" (always awake) to search for incoming transmissions. However, keeping LP receivers 120, 122 in an "always on" (always awake) state presents a challenge because the received signal level is typically low due to high channel attenuation caused by the patient's anatomy. Furthermore, keeping the receivers awake will drain the battery 114 faster than might be expected.

[0073] According to some embodiments, the first receiver 120 may always keep the first channel active (wake-up) (including when the second channel is inactive (sleep)) in order to listen for messages from a remote IP. The second receiver 122 may be assigned as a second activation protocol to trigger a protocol, wherein the second receiver 122 becomes active (wake-up) in response to a trigger event detected on the first receiving channel (e.g., activating the second channel at the local LP when an incoming signal corresponds to an LP wake-up notification). The terms “active,” “on,” “wake-up,” and “enabled” are used interchangeably herein.

[0074] Still referencing Figure 2 Each LP 102a, 102b is shown as including a controller 112 and a pulse generator 116. The controller 112 may include, but is not limited to, a microprocessor (or equivalent control circuitry), RAM and / or ROM memory, logic and timing circuitry, state machine circuitry, and I / O circuitry. The controller 112 may also include, for example, timing control circuitry to control the timing of stimulation pulses (e.g., pacing rate, atrioventricular (AV) delay, intra-atrial (AA) conduction delay, or intraventricular (VV) conduction delay, etc.). Such timing control circuitry can also be used for timing refractory periods, blanking intervals, noise detection windows, evoked response windows, alarm intervals, marker channel timing, crosstalk protection duration, etc. The controller 112 may further include other dedicated circuitry and / or firmware / software components to assist in monitoring various conditions of the patient's heart and managing pacing therapy. For example, the controller 112 may include an arrhythmia detector, which may be similar to the referenced below. Figure 8The cardiac arrhythmia detector 834 is discussed.

[0075] The controller 112 and pulse generator 116 can be configured to send event messages via electrodes 108 in a manner that does not unintentionally capture the heart in the chambers where LPs 102a and 102b are located (e.g., when the associated chamber is not in an inactive state). Additionally, LPs 102a and 102b receiving the event message can enter an "event inactive" state (or event blanking state) after receiving the event message. The event inactive / blanking state can be set to extend for a defined period after receiving the event message to prevent the receiving LPs 102a and 102b from unintentionally sensing another signal as an event message that might trigger a re-triggering. For example, the receiving LPs 102a and 102b can detect measurement pulses from another LP 102a or 102b or programmer 109.

[0076] Since conductive communication receivers 120, 122 (or alternatively, only a single conductive communication receiver) and pulse generator 116 are used to perform conductive communication, these components can be considered part of conductive communication transceiver 124. Conductive communication transceiver 124 may alternatively include alternative and / or additional components that enable the LP to send and receive conductive communication messages with another LP and / or with another type of IMD (such as ICD 106) and / or external devices (such as programmer 109). For example, while the same pulse generator 116 can be used to generate pacing pulses (for pacing a patient's heart) and conductive communication pulses (for communicating with another LP, another type of IMD, and / or external devices), conductive communication transceiver 124 may also include its own dedicated pulse generator. For another example, as described above, conductive communication transceiver 124 may also include only a single receiver instead of two receivers 120, 122. Other variations are also possible and are within the scope of the embodiments described herein.

[0077] Still referencing Figure 2LP 102 is also shown to include an antenna 118 coupled to a radio frequency (RF) communication transceiver 134 configured to transmit and receive RF communication messages using RF communication protocols such as Bluetooth, WiFi, Bluetooth Low Energy (BLE), MedRadio, etc. In some embodiments, the antenna 118 may be integrated into a fixing mechanism (e.g., 205) of the LP, in which case the antenna may be referred to as a fixed antenna. This is disclosed and referenced in U.S. Patent No. 10,583,300, entitled “Leadless implantable medical device with fixation antennamember.” Figures 3 to 5 An example implementation of a fixed antenna is described, and the patent is incorporated herein by reference as if fully set forth herein. In other embodiments, the antenna 118 is separate from and different from the fixing mechanism of LP 102. The specific type, location, and form factor of the antenna may depend on the specific type and form factor of the IMD.

[0078] RF transceiver 134 consumes more battery power than conducted transceiver 124. More generally, using conducted communication from LP 102 (or other type of IMD) is more power efficient than using RF communication to communicate with another LP 102 (or other type of IMD). Therefore, according to certain embodiments of the present technology, LP 102 (or other type of IMD) is configured to primarily use conducted communication to send and receive messages, and RF communication is used as a backup or auxiliary type of communication that can be used when conducted communication is deactivated (also known as turned off), unsuccessful, or otherwise defective, as will be described in further detail below.

[0079] It is possible that LPs 102a and 102b can only communicate with each other and / or with other devices (such as programmer 109 and / or ICD 106) using conducted communication only. In this case, antenna 118 and RF communication transceiver 134 can be eliminated. Alternatively, LPs 102a and 102b can be configured to communicate using RF communication only without utilizing conducted communication. In this case, certain circuitry, such as receivers 120 and 122, can be eliminated. Alternatively or additionally, LPs 102a and 102b can utilize another type of communication, such as inductive communication. In this case, LPs 102a and 102b can each include a corresponding inductive communication coil.

[0080] According to some embodiments herein, programmer 109 can communicate via programmer-to-LP channel with LPs 102a and 102b using the same communication scheme. External programmer 109 can listen to event messages transmitted between LPs 102a and 102b and synchronize the programmer to implant communication, such that programmer 109 does not transmit communication messages until after the i2i message passing sequence is complete.

[0081] In some embodiments, each individual LP 102 may include an airtight housing 110 and at least two leadless electrodes 108, the airtight housing 110 being configured to be placed on or attached to the inside or outside of a heart chamber, and the at least two leadless electrodes 108 being located near the housing 110 and configured to communicate bidirectionally with at least one other device (e.g., NV-ICD 106) inside or outside the body.

[0082] Figure 2 A single LP 102 (e.g., LP 102 a or 102 b) is depicted, and the functional elements of the LP, substantially enclosed within an airtight housing 110, are shown. The LP 102 has at least two electrodes 108 located within, above, or near the housing 110 for delivering pacing pulses to the muscles of the heart chambers and sensing electrical activity from the muscles of the heart chambers, and for bidirectional communication with at least one other device inside or outside the body. Airtight feedthroughs 130, 131 conduct electrode signals through the housing 110. The housing 110 contains a primary battery 114 for powering pacing, sensing, and communication. The housing 110 also includes circuitry 132 for sensing cardiac activity from the electrodes 108, receivers 120, 122 for receiving information from at least one other device via the electrodes 108, and a pulse generator 116 for generating pacing pulses for delivery via the electrodes 108 and also for transmitting information to at least one other device via the electrodes 108. The housing 110 may optionally include circuitry for monitoring the health of the device, such as a battery ammeter 136 and a battery voltmeter 138, and may also include circuitry for controlling operation in a predetermined manner.

[0083] Electrode 108 can be configured to communicate bidirectionally among multiple leadless pacemakers (LPs) and / or implanted ICDs 106 to coordinate pacing pulse delivery and optional other therapeutic or diagnostic features using messages that identify an event at the individual pacemaker initiating the message, and the pacemaker receiving the message responds according to the message's indication based on its source. LPs 102a, 102b that receive event messages respond according to the event message's indication based on its source or location. In some embodiments or cases, two or more leadless electrodes 108 can be configured to communicate bidirectionally among one or more LPs 102 and / or ICDs 106 and transmit data including a designated code for an event detected or created by a separate pacemaker. Each pacemaker can be configured to issue a unique code corresponding to the event type and the location of the sending pacemaker.

[0084] In some embodiments, individual LPs 102a, 102b can be configured to deliver pacing pulses encoded with event messages, wherein codes are assigned based on pacemaker location, and individual LPs 102a, 102b are configured to send messages to one or more other LPs via the event message-encoded pacing pulses. The receiving LP or pacemaker is adapted to respond to the message in a predetermined manner based on the type and location of the event.

[0085] Furthermore, the information transmitted on the input channel may also include event messages from another LP, indicating that the other LP has sensed a heartbeat or delivered a pacing pulse, and identifying the location of another pacemaker. For example, LP 102 b can receive event messages from LP 102 a and relay them to the programmer. Similarly, the information transmitted on the output channel may also include messages to another LP or multiple LPs or to the ICD: that the transmitting LP has sensed a heartbeat or delivered a pacing pulse at the location of the transmitting pacemaker.

[0086] Refer again Figure 1 and Figure 2 In addition to one or more LPs 102a, 102b, system 100 may also include an ICD 106, which is configured to be implanted in electrical contact with the heart chambers and to perform cardiac rhythm management functions in combination with the implantable ICD 106. According to the embodiments discussed herein, the implantable ICD 106 and one or more LPs 102a, 102b are configured to communicate with each other without leads via information transmission through body tissue and / or wireless transmission between transmitter and receiver.

[0087] In another embodiment, system 100 includes at least one LP 102a, 102b configured to be implanted in electrical contact with a cardiac chamber and configured to perform cardiac pacing functions in conjunction with a co-implanted ICD 106. Each LP 102 includes at least two leadless electrodes 108 configured to deliver cardiac pacing pulses, sense induced and / or natural cardiac electrical signals, and transmit information to the co-implanted ICD 106.

[0088] As shown in the illustrative embodiments, LP 102 a, 102 b may include two or more leadless electrodes 108 configured to deliver cardiac pacing pulses, sense induced and / or natural cardiac electrical signals, and communicate bidirectionally with the co-implanted ICD 106.

[0089] Each LP 102a, 102b can be configured to operate in a corresponding specific location and to have a corresponding specific function during manufacturing and / or programmed via an external programmer. Bidirectional communication between multiple LPs can be arranged to transmit notifications of sensed heartbeats or delivered pacing pulse events, along with the encoded type and location of the events, to another implanted pacemaker or multiple pacemakers. The receiving LP 102a, 102b decodes the information and responds according to the location of the receiving pacemaker and predetermined system functions.

[0090] In some embodiments, LPs 102a and 102b are configured to be implantable in any chamber of the heart, i.e., an atrium (RA, LA) or a ventricle (RV, LV). Furthermore, for a dual-chamber configuration, multiple LPs can be implanted co-located (e.g., one in the RA and one in the RV, one in the RV and one in the coronary sinus near the LV). Certain pacemaker parameters and functions depend on (or are assumed to be) knowledge of the chamber in which the LP is implanted (and therefore interacts with, e.g., pacing and / or sensing). Some non-limiting examples include evoked response algorithms, atrial fibrillation (AF) suppression in local chambers, silencing, and refractory periods. Therefore, each LP should know the identity of the chamber in which (or on which) the LP is implanted, and processes can be implemented to automatically identify the local chamber associated with each LP.

[0091] The process used for chamber identification can also be applied to subcutaneous pacemakers and ICDs with leads. Identification and / or verification of devices with one or more implantable leads, and the chambers in which the leads are implanted, can be useful in several relevant scenarios. For example, for dual-chamber frequency-response pacing devices or cardiac resynchronization therapy (CRT) devices, automated identification and verification can prevent clinicians from inadvertently placing a V-lead into the A-port of the implantable medical device, and vice versa. As another example, for single-chamber frequency-response pacing devices, automated identification of the implantable chamber can enable the device and / or programmer to select and present an appropriate subset of pacing modes (e.g., AAI or VVI), and allow the implantable device to utilize an appropriate set of settings and algorithms (e.g., V-auto-capture and ACap-verification, sensing sensitivity, etc.).

[0092] In an embodiment, Figure 2 The primary battery 114 has a positive terminal 140 and a negative terminal 142. Current from the positive terminal 140 of the primary battery 114 flows through an optional shunt 144 to an optional regulator circuit 146 to generate a positive voltage source 148 suitable for powering the remaining circuitry of LP 102. The shunt 144 enables an optional battery ammeter 136 to provide an indication of battery current consumption to the controller 112 and indirectly to an indication of device health. The illustrative power source may be the primary battery 114.

[0093] Still referencing Figure 2 The LP is shown as including an optional temperature sensor 152. The temperature sensor can be any of a variety of known temperature sensors, or it can be a temperature sensor developed in the future. For one example, the temperature sensor 152 can be a thermistor, thermocouple, resistance thermometer, or silicon bandgap temperature sensor, but is not limited thereto. Regardless of how the temperature sensor 152 is implemented, preferably, the temperature sensed by the sensor is provided as a digital signal to the controller 112, indicating the blood temperature of the patient with the LP implanted. The temperature sensor 152 can be hermetically sealed within the housing 110, but this is not always the case. The temperature sensor 152 can be used in various ways. For example, the temperature sensor 152 can be used to detect the patient's activity level to adjust the pacing rate, i.e., for frequency-responsive pacing. When a person begins to exercise, their core body temperature initially decreases, and then eventually rises after prolonged exercise. Afterward, when the person stops exercising, their core body temperature will return to its baseline. Therefore, the controller 112 can be configured to detect the patient's activity level based on the core blood temperature measurement obtained using the temperature sensor 152.

[0094] refer to Figure 2The LP is also shown to include an optional accelerometer 154, which can be hermetically contained within the housing 110. Accelerometer 154 can be any of various types of known accelerometers, or can be an accelerometer developed in the future. For example, accelerometer 154 can be or include, for example, a MEMS (microelectromechanical systems) multi-axis accelerometer utilizing capacitive or optical cantilever beam technology, or a piezoelectric accelerometer employing the piezoelectric effect of certain materials to measure dynamic changes in mechanical variables. For example, accelerometer 154 can be used to detect the patient's activity level to adjust the pacing rate, i.e., for frequency-responsive pacing. The outputs of both accelerometer 154 and temperature sensor 152 can also be used to monitor the patient's activity level. Alternatively or additionally, the patient's activity level can be monitored based on the patient's heart rate, such as from an electrogram (EGM) sensed using electrode 108 and / or from a plethysmographic signal obtained using a plethysmographic sensor (not shown) or a phonocardiogram sensor (not shown), but is not limited thereto. One or more signals generated and output by accelerometer 154 can be analyzed regarding frequency content, energy, duration, amplitude, and / or other characteristics. Such signals may or may not be amplified and / or filtered before analysis. For example, filtering can be performed using low-pass, high-pass, and / or band-pass filters. The signal output by accelerometer 154 can be an analog signal, which can be analyzed in the analog domain, or it can be converted to a digital signal (via an analog-to-digital converter) and analyzed in the digital domain. Alternatively, the signal output by accelerometer 154 may already be in the digital domain. One or more signals output by accelerometer 154 can be analyzed by controller 112 and / or other circuitry. In some embodiments, accelerometer 154 is packaged with an integrated circuit (IC) designed to analyze the signals it generates. In such embodiments, one or more outputs of the packaged sensor / IC can be an indication of acceleration along one or more axes. In other embodiments, the accelerometer 154 may be packaged with an IC that performs signal conditioning (e.g., amplification and / or filtering), performs analog-to-digital conversion, and stores digital data (indicating sensor output) in a memory (e.g., RAM, which may or may not be in the same package). In such embodiments, the controller 112 or other circuitry may read the digital data from the memory and analyze it. Other variations are also possible and are within the scope of embodiments of the present technology. According to certain embodiments of the present technology, as will be described in more detail below, the sensor signals generated by the accelerometer 154 of an LP implanted in or on a heart chamber can be used to detect mechanical cardiac activity associated with another heart chamber.

[0095] In various embodiments, LPs 102a and 102b can manage power consumption to draw limited power from the battery, thereby reducing device size. Each circuit in LP 102 can be designed to avoid large peak currents. For example, cardiac pacing can be achieved by discharging a tank capacitor (not shown) across the pacing electrodes. Recharging of the tank capacitor is typically controlled by a charge pump circuit. In a particular embodiment, the charge pump circuit is throttled to recharge the tank capacitor at a constant power from the battery.

[0096] In some embodiments, the controller 112 in LP 102 can access signals on electrode 108 and can examine the duration of an output pulse from another LP 102 as a signature for determining the validity of trigger information, and for a signature arriving within a predetermined limit, activate the delivery of a pacing pulse after a predetermined delay of zero or more milliseconds. The predetermined delay can be preset at manufacturing time, programmed via an external programmer, or determined by adaptive monitoring to facilitate the identification of the trigger signal and its differentiation from noise. In some embodiments or under certain conditions, the controller 112 can examine the waveform of an output pulse from another LP as a signature for determining the validity of trigger information, and for a signature arriving within a predetermined limit, activate the delivery of a pacing pulse after a predetermined delay of zero or more milliseconds.

[0097] Figure 3 Example shape factors of LPs 102 A and 102 b are shown. Each LP may include a hermetically sealed housing 202 on which electrodes 108 a and 108 b are disposed (e.g., Figure 2 As shown in Figure 110, electrode 108a can be separated from but partially surrounded by the fixation mechanism 205, and electrode 108b can be disposed on housing 202. The fixation mechanism 205 can be a fixation spiral, multiple hooks, barbs, or other attachment features configured to attach the LP to tissue (such as cardiac tissue). As described above, the antenna (e.g., 118) can be implanted at least partially by or as part of the fixation mechanism. Electrodes 108a and 108b are... Figure 2 As shown in and referenced above Figure 2 An example of electrode 108 is discussed.

[0098] The housing may also include an electronics compartment 210 within the housing, which contains the electronic components required to operate the LP, including, for example, a pulse generator, transceiver, battery, and processor for operation. The hermetically sealed housing 202 may be suitable for implantation on or inside a human heart and may be, for example, cylindrical, rectangular, spherical, or any other suitable shape.

[0099] The housing may comprise conductive, biocompatible, inert, and anolyte-safe materials, such as titanium, 316L stainless steel, or other similar materials. The housing may also include an insulator disposed on the conductive material to separate electrodes 108a and 108b. The insulator may be an insulating coating on a portion of the housing between the electrodes and may comprise materials such as silicone, polyurethane, parylene, or another biocompatible electrical insulator commonly used in implantable medical devices. Figure 3 In some embodiments, a single insulator 208 is disposed along the portion of the housing between electrodes 108a and 108b. In some embodiments, the housing itself may comprise an insulator instead of a conductor, such as alumina ceramic or other similar material, and the electrodes may be disposed on the housing.

[0100] like Figure 3 As shown, the LP may also include a head assembly 212 to isolate 108a and 108B. The head assembly 212 may be made of PEEK, tecothane or other biocompatible plastics and may contain a ceramic-to-metal feedthrough, a glass-to-metal feedthrough or other suitable feedthrough insulators known in the art.

[0101] Electrodes 108a and 108b may include pacing / sensing electrodes or return electrodes. Low-polarity coatings may be applied to the electrodes, such as sintered platinum, platinum-iridium, iridium, iridium oxide, titanium nitride, carbon, or other materials commonly used to reduce polarization effects. Figure 3 In this configuration, electrode 108a can be a pacing / sensing electrode, and electrode 108b can be a return electrode. Electrode 108b can be a portion of the conductive housing 202 excluding the insulator 208.

[0102] Several techniques and structures can be used to attach the housing 202 to the inner or outer wall of the heart. A spiral fixation mechanism 205 allows the device to be inserted into the endocardium or epicardium via a guiding catheter. A rotatable catheter can be used to rotate the housing and force the fixation device into the heart tissue, thereby securing the device (and...) Figure 3 Electrode 108 a) is fixed in contact with stimulable tissue. Electrode 108 b can be used as an independent electrode for sensing and pacing. The fixation mechanism may be partially or entirely coated for electrical insulation and may include a steroid-eluting matrix on or near the device to minimize fibrotic reactions, as is known in conventional pacing electrode leads.

[0103] Implant-to-Implant Event Message Passing

[0104] LPs 102 A and 102 b can coordinate their operation with each other in various ways via implant-to-implant (i2i) communication through event messages. The terms i2i event message and i2i event tag are used interchangeably herein to refer to event-related messages transmitted from one implantable device to another and LP / LP operation-related messages (although external devices, such as programmers, can also receive i2i event messages). In some embodiments, LPs 102 a and LP 102 b operate as two independent leadless pacemakers, maintaining pacemaker dual-chamber functionality via a “master / slave” operation configuration. For descriptive purposes, ventricular LP 102 b should generally be referred to as “vLP”, and atrial LP 102 a should generally be referred to as “aLP”, as described above. LPs 102 designated as master devices (e.g., vLPs) can implement all or most dual-chamber diagnostic and therapeutic determination algorithms. For the purposes of the following description, it is assumed that vLP is the “master” device and aLP is the “slave” device. Alternatively, aLP may be designated as the master device and vLP as the slave device. The master device coordinates most or all decisions and timing determinations (including, for example, rate response changes).

[0105] Figure 4 This is a timing diagram 400 illustrating an example of I2I conduction communication used for pacing events. I2I conduction communication can, for example, be transmitted from LP 102 a to LP 102 b. (As shown...) Figure 4 As shown, in this embodiment, an i2i transmission 402 is transmitted before the pacing pulse 404 is delivered by the transmitting LP (e.g., LP102A). This enables the receiving LP (e.g., LP102b) to prepare for the remote delivery of the pacing pulse. The i2i transmission 402 includes an envelope 406, which may include one or more individual pulses. For example, in this embodiment, the envelope 406 includes a low-frequency pulse 408, followed by a high-frequency pulse train 410. The duration T of the low-frequency pulse 408 is... i21LF And the high-frequency pulse train 410 duration T i21HF The end of the low-frequency pulse 408 and the beginning of the high-frequency pulse train 410 are separated by a gap period Ti2iGap. In an alternative embodiment, instead of sending the envelope 406 before the pacing pulse 404, the envelope 406 may be sent during the refractory period after the delivery of the pacing pulse.

[0106] like Figure 4As shown, the i2i transmission 402 has a duration of Ti2iP, and the pacing pulse 404 has a duration of Tpace. The end of the i2i transmission 402 and the start of the pacing pulse 404 are separated by a delay period TdelayP. The delay period can be, for example, between approximately 0.0 and 10.0 milliseconds (ms), particularly between approximately 0.1 ms and 2.0 ms, and more particularly approximately 1.0 ms. As used herein, the term approximately means + / - 10% of the specified value.

[0107] Figure 5 This is a timing diagram 500 illustrating an example of I2I communication used for sensing events. I2I communication can, for example, be transmitted from LP 102 a to LP 102 b. Figure 5 As shown in the diagram, in this embodiment, when the sensed intrinsic activation 502 crosses the sensing threshold 504, the transmitting LP (e.g., LP 102 a) detects the sensed event. After a predetermined delay period Tdelay following the detection, the transmitting LP transmits data for a duration of T. i2iS The i2i transmission 506. The delay period can be, for example, between about 0.0 and 10.0 milliseconds (ms), particularly between about 0.1 ms and 2.0 ms, and more particularly about 1.0 ms.

[0108] Similar to I2I transmission 402, I2I transmission 506 may include an envelope that may include one or more individual pulses. For example, similar to envelope 406, the envelope of I2I transmission 506 may include low-frequency pulses followed by a high-frequency pulse train. In some embodiments, I2I transmission 506 is transmitted during a refractory period following a sensed event.

[0109] Optionally, where the first LP is located in the atrium and the second LP is located in the ventricle, the first LP generates an AS / AP event flag to indicate that an atrial sensing (AS) event or an atrial pacing (AP) event has occurred or will occur in the near future. For example, the AS and AP event flags can be sent after the corresponding AS or AP event. Alternatively, the first LP can transmit the AP event flag slightly before delivering the atrial pacing pulse. Alternatively, where the first LP is located in the atrium and the second LP is located in the ventricle, the second LP initiates an atrioventricular (AV) interval after receiving an AS or AP event flag from the first LP; and initiates a post-AV blanking (PAVB) interval after receiving an AP event flag from the first LP.

[0110] Optionally, the first and second LPs can operate in a "pure" master / slave relationship, wherein the master LP delivers a "command" flag in addition to or instead of an "event" flag. The command flag instructs the slave LP to perform an action such as delivering a pacing pulse. For example, in a pure master / slave relationship, when the slave LP is located in the atrium and the master LP is located in the ventricle, upon receiving an AP command flag from the master LP, the slave LP will immediately deliver a pacing pulse to the atrium.

[0111] According to some embodiments, communication and synchronization between the aLP and vLP are achieved via conducted communication (according to the i2i communication protocol) of tags / commands in event messages. As explained above, conducted communication refers to event messages transmitted from the sensing / pacing electrodes at frequencies outside the RF (e.g., Wi-Fi or BLE) frequency range. Alternatively, event messages can be transmitted via a communication channel operating within the RF frequency range. The following figures and corresponding descriptions illustrate non-limiting examples of tags that can be transmitted in event messages. The following figures and corresponding descriptions also include descriptions of the tags and examples of the results occurring in the LP receiving the event message. Table 1 shows example event tags transmitted from the aLP to the vLP, while Table 2 shows example event tags transmitted from the vLP to the aLP. In a master / slave configuration, an AS event flag is transmitted from the aLP each time an atrial event is sensed outside the postventricular atrial blanking (PVAB) interval or some other alternatively defined atrial blanking period. An AP event flag is transmitted from the aLP each time the aLP delivers a pacing pulse in the atrium. aLP can restrict the transmission of AS event flags, thus transmitting the AS event flag when an atrial event is sensed outside the PVAB interval and outside the postventricular atrial refractory period (PVARP) or some other alternatively defined atrial refractory period. Alternatively, aLP can transmit the AS event flag each time an atrial event is sensed, instead of restricting the transmission of AS event flags based on PVARP.

[0112]

[0113] Table 1

[0114] As shown in Table 1, when the aLP transmits an event message including an AS event flag (indicating that the aLP senses an intrinsic atrial event), the vLP starts the AV interval timer. If the aLP transmits AS event flags for all sensed events, the vLP will preferably first determine that the PVAB or PVARP interval is not active before starting the AV interval timer. However, if the aLP only sends an AS event flag when it senses an intrinsic signal outside the PVAB or PVARP interval, the vLP can start the AV interval timer upon receiving the AS event flag without first checking the PVAB or PVARP status. When the aLP transmits an AP event flag (indicating that the aLP has delivered or is about to deliver a pacing pulse to the atrium), the vLP starts the PVAB timer and the AV interval timer, provided that the PVARP interval is inactive. The vLP can also blank its sensing amplifier to prevent possible crosstalk sensing from remote pacing pulses delivered by the aLP.

[0115]

[0116] Table 2

[0117] As shown in Table 2, when the vLP senses a ventricular event, it sends an event message including a VS event flag, in response to which the aLP can start a PVARP interval timer. When the vLP delivers or is about to deliver a pacing pulse in the ventricle, it transmits a VP event flag. When the aLP receives the VP event flag, it starts a PVAB interval timer and a PVARP interval timer. The aLP can also blank its sensing amplifier to prevent possible crosstalk sensing of remote pacing pulses delivered by the vLP. The vLP can also send an event message including an AP command flag to command the aLP to deliver an immediate pacing pulse in the atrium upon receiving the command, without delay.

[0118] The aforementioned event markers are examples of a subset of markers that can be used to enable both the aLP and vLP to maintain full dual-chamber functionality. In one embodiment, the vLP can execute all dual-chamber algorithms, while the aLP can execute atrial-based hardware-related functions, such as PVAB, implemented natively within the aLP. In this embodiment, the aLP is effectively viewed as a remote “wireless” atrial pacing / sensing electrode. In another embodiment, the vLP can execute most, but not all, of the dual-chamber algorithms, while the aLP can execute a subset of diagnostic and therapeutic algorithms. In alternative embodiments, the vLP and aLP can execute diagnostic and therapeutic algorithms equally. In some embodiments, decision responsibility can be separately assigned to either the aLP or the vLP. In other embodiments, decision responsibility can involve joint input and responsibility.

[0119] Messages transmitted between LPs (e.g., aLP and vLP) are generally referred to herein as i2i messages because they are implanted-to-implant messages. As described above, such messages may include event tokens that enable one LP to notify another LP of pacing events or sensed events. For example, in some embodiments, whenever aLP 102 a senses an atrial event or paces the right atrium, aLP will send an i2i message to vLP 102 b to notify vLP of the sensed or paced event in the atrium. In response to receiving such an i2i message, vLP 102 b may start one or more timers that enable vLP to sense or pace in the right ventricle. Similarly, whenever vLP senses a ventricular event or paces the right ventricle, vLP may send an i2i message to aLP 102 a.

[0120] I2I messages sent between LPs can be relatively short messages that only allow a first LP to notify a second LP of an event sensed by or caused by the first LP (synchronization), and vice versa. Such I2I messages may be referred to herein as event-tagged I2I messages, or more concisely as event I2I messages. In some cases, I2I messages sent between LPs can be extended I2I messages, which include extensions (in addition to event tags). In some embodiments, an extended I2I message includes an event tag (e.g., 9 bits), followed by an extended indicator (e.g., 2 bits), followed by an extended message payload portion (e.g., 17 bits), followed by a Cyclic Redundancy Check (CRC) code (e.g., 6 bits) or some other type of error detection and correction code. Other variations are also possible.

[0121] Crosstalk protection

[0122] As described above, to mitigate (and preferably prevent) crosstalk that adversely affects a dual-chamber LP system (or more generally, a multi-chamber LP system), each LP in the system can independently monitor for potential crosstalk that may be caused by another LP delivering pacing pulses. Then, in response to the detection of potential crosstalk, the LP that detected the potential crosstalk can blank its sensing circuitry for a period of time, using the sensing circuitry to monitor inherent events in the chamber where (or on which) the LP is implanted. Alternatively or additionally, in response to the detection of potential crosstalk, the LP that detected the crosstalk can ignore any potential inherent events detected by its sensing circuitry for a period of time, assuming that such detection of the inherent event is actually due to crosstalk. More generally, the LP that detected potential crosstalk can activate crosstalk protection in response to the detection of potential crosstalk.

[0123] As described above, determining the appropriate crosstalk protection duration for use in a dual-chamber LP system (and more generally, a multi-chamber LP system) is no trivial task, as various factors exist that can affect the appropriate crosstalk protection duration for an LP system. If the crosstalk protection duration is set too short, it may result in residual detection of crosstalk. Conversely, if the crosstalk protection duration is set too long, it may result in missing legitimate locally inherent events (i.e., failure to be detected). Certain embodiments of the present technology, which will now be described in further detail below, relate to systems, subsystems, and methods for specifying and utilizing the appropriate crosstalk protection duration for an LP in a multi-chamber LP system.

[0124] Figure 6 This is an example timing diagram used to illustrate how pacing pulses delivered by a second LP (LP2) implanted in (or on) a remote cardiac chamber (e.g., the right atrium) can cause crosstalk that might be incorrectly detected by a first LP (LP1) implanted in (or on) a local cardiac chamber (e.g., the right ventricle) as inherent depolarization of the local cardiac chamber. Waveform 602 is the signal sensed between a pair of electrodes (e.g., 108 a and 108 b) of LP1 before any filtering is performed. Waveform 604 is the sensed signal 602 after it has been filtered by the sensing circuitry (e.g., 132) of LP1, which LP1 uses to monitor the inherent depolarization of the local cardiac chamber in which (or on) LP1 is implanted. Note that the vertical (also known as the y-axis) scaling of signals 602 and 604 is not equal; that is, signal 604 is amplified on the y-axis relative to signal 602. Horizontal dashed lines 606 and 608 represent positive and negative intrinsic depolarization sensing thresholds (e.g., at +1.0 mV and -1.0 mV, or at +0.5 mV and -0.5 mV, but not limited thereto), which are used by the sensing circuitry of LP 1 (e.g., 132) to detect intrinsic depolarization of a local cardiac chamber (e.g., the right ventricle) when the amplitude of the filtered signal 604 exceeds the intrinsic depolarization sensing threshold (represented by horizontal dashed lines 606 and 608). Pulse 610 indicates when LP 1 (e.g., LF receiver 120 of LP 1) detects possible crosstalk. In other words, pulse 610 indicates the timing at which LP 1 detects possible crosstalk. As will be further described in detail below, the possible crosstalk detected by LP 1 may not be crosstalk, but may actually be part of a valid message received from another device (e.g., a wake-up pulse). The pulse within the dashed ellipse 612 is an interrupt pulse. This interrupt pulse is generated at a frequency not exceeding once per clock cycle (of the LP 1 clock) when the filtered signal 604 exceeds the inherent depolarization sensing threshold (represented by horizontal dashed lines 606 and 608). Note that no interrupt pulse occurs when the amplitude of the filtered signal 604 does not exceed the inherent depolarization sensing threshold. Although in Figure 6 The diagram shows both positive and negative intrinsic depolarization sensing thresholds, but the filtered signal 604 can be rectified so that it is always a positive signal. In this case, only the positive intrinsic depolarization sensing threshold 606 needs to be used.

[0125] As from Figure 6 Understandably, if the crosstalk protection duration is set to approximately 30 milliseconds, all interruptions (within dashed ellipse 612) will be ignored (or not generated, depending on the implementation) after a possible crosstalk is detected (as indicated by pulse 610). However, if the crosstalk protection duration is set too short, for example, 20 milliseconds, LP 1 may still incorrectly detect the possible inherent depolarization of the local chamber in which LP 1 is implanted, because the ringing of the filtered signal 604 still has an amplitude exceeding the inherent depolarization sensing threshold (indicated by horizontal dashed lines 606 and 608) after the excessively short crosstalk protection duration ends. On the other hand, if the crosstalk protection duration is set too long, for example, 50 milliseconds, LP 1 will be unable to detect the increased probability of actual inherent depolarization of the local chamber in which (or on) LP 1 is implanted.

[0126] According to certain embodiments of the present technology, the duration of crosstalk protection used by the LP is determined based on certain information about a multi-chamber LP system including the LP. For the purposes of the following discussion, it is assumed that such a multi-chamber LP system includes a first leadless pacemaker (LP 1) (e.g., 102a) and a second leadless pacemaker (LP 2) (e.g., 102b), the first leadless pacemaker (LP 1) being configured to be implanted in or on a first heart chamber (e.g., right atrium) of a patient's heart and to deliver pacing pulses to the first heart chamber, and the second leadless pacemaker (LP 2) being configured to be implanted in or on a second heart chamber (e.g., right ventricle) of the patient's heart and to deliver pacing pulses to the second heart chamber. In such a system, it is also assumed that each LP includes a corresponding sensing circuit (e.g., 132) configured to be used by the LP to detect the inherent depolarization of the local heart chamber in which (or on) the LP is implanted. As explained below, each LP may also include a corresponding crosstalk detection circuit configured for use by the LP to detect potential crosstalk that may be caused by another LP delivering one of the pacing pulses. Additionally, it is assumed that each LP includes a corresponding pulse generator (e.g., 116) configured for use by the LP to generate pacing pulses that are delivered to a local cardiac chamber in which (or on which) the LP is implanted. Such a pulse generator may include one or more pacing capacitors and one or more return capacitors, which together have capacitance (Cpace) and are configured to store and deliver energy used to generate the pacing pulses.

[0127] For the purposes of this discussion, a cardiac chamber in which a specific LP is implanted or on can be referred to as a “local chamber,” while another chamber (in which no specific LP is implanted or on) can be referred to as a “remote chamber.” From the perspective of an LP implanted or on a local cardiac chamber (e.g., the right atrium), simulations and tests have shown that the amplitude of a pacing pulse delivered to a remote cardiac chamber (e.g., the right ventricle) by another LP implanted or on a remote cardiac chamber is positively correlated with the duration of detectable crosstalk (caused by the other LP delivering the pacing pulse to the remote chamber) by the LP implanted or on a local cardiac chamber (e.g., the right atrium), as described above. The amplitude of the pacing pulse can be quantified, for example, according to its pacing pulse amplitude (P0). PA ) and / or its pacing pulse width (P PW ), and preferably both. More specifically, the amplitude of the pacing pulse (and more specifically, the delivered pacing pulse charge (P) PQ A feasible first-order approximation of the magnitude of is P. PA × P PW Pacemaker pulse charge (P) PQ An even more accurate approximation also considers the capacitance (Cpace) of one or more pacing capacitors in the remote LP, which stores the energy used to generate the pacing pulse delivered to the remote chamber, and the pacing output impedance (R). load The following equation is used (in equation (EQ1), the coefficient 1000 is used to scale the numerator to match the units of the denominator, and therefore, depending on the specific implementation, it may be different or eliminated in some implementations):

[0128]

[0129] (Equation 1)

[0130] Furthermore, simulations and testing have shown that the sensitivity of the sensing circuitry (e.g., 132) of a LP implanted in or on a local cardiac chamber (e.g., the right atrium) is negatively correlated with the duration for which crosstalk (caused by another LP delivering pacing pulses to a remote chamber) can be detected by the LP implanted in or on a local cardiac chamber (e.g., the right atrium), assuming the sensitivity is specified by a sensing detection threshold. If the sensitivity of the sensing circuitry (e.g., 132) is alternatively specified by the gain of the sensing circuitry, while the sensing detection threshold remains constant, then the sensitivity (and more specifically, the gain) is alternatively positively correlated with the duration for which crosstalk (caused by another LP delivering pacing pulses to a remote chamber) can be detected by the LP implanted in or on a local cardiac chamber (e.g., the right atrium).

[0131] Furthermore, bench tests in a saline bath are performed and the results are analyzed to create a set of mathematical crosstalk protection models or equations that capture the dependence of crosstalk protection duration on the pacing pulse amplitude (by parameters pulse amplitude and pulse width) from the remote LP and the sensing detection threshold of the sensing circuit (e.g., 132) of the local LP, assuming a fixed distance and orientation between those LPs.

[0132] Based on the results of bench testing, the following equation (aka model) is derived to specify the duration of crosstalk protection to be used by the LP (e.g., 102 b) implanted in the right ventricle (RV), where another LP (e.g., 102 a) is implanted in the right atrium (RA):

[0133] (Equation 2)

[0134] in,

[0135] i2iCTP RV This refers to the duration of crosstalk protection used by the LP implanted in the RV.

[0136] Km is a constant scaling factor determined for the patient population.

[0137] Kb is a constant offset factor determined for a specific patient population.

[0138] P PQ_RA The pacing pulse charge is delivered by the LP implanted in the RA for each pacing pulse.

[0139] Sens RV It is the sensing detection threshold of the LP sensing circuit implanted in the RV, and

[0140] ln is the natural logarithm function.

[0141] Additionally, based on bench test results, the following equation (aka model) is derived to specify the crosstalk protection duration to be used by the LP implanted in the RA (e.g., 102 a), where another LP (e.g., 102 b) is implanted in the RV:

[0142] (Equation 3)

[0143] in,

[0144] i2iCTP RA This refers to the duration of crosstalk protection used by the LP implanted in the RA.

[0145] K m It is a constant scaling factor determined for a specific patient group.

[0146] K bIt is a constant offset factor determined for a specific patient population.

[0147] K c It is another constant scaling factor determined for the patient population.

[0148] X0 is another constant offset factor determined for the patient population.

[0149] P PQ_RV The pacing pulse charge is delivered by the LP implanted in the RV for each pacing pulse.

[0150] Sens RA It is the sensing detection threshold of the LP sensing circuit implanted in RA.

[0151] ln is the natural logarithm function, and

[0152] sech is a hyperbolic secant function.

[0153] For a specific analysis and implementation, the values ​​of Km, Kb, Ka, Kc, and X0 are defined as follows:

[0154] K m =9,

[0155] K b =-3,

[0156] K a =8,

[0157] K c =2, and

[0158] X0=1.9.

[0159] The embodiments of the technology described herein are not limited to using the equations specified above. However, such equations can be used in specific embodiments of the technology. In other words, such equations are specific examples of numerous equations that can be used to implement the various embodiments described herein.

[0160] Furthermore, according to some embodiments, another scaling factor related to the distance and / or angle between the first and second LPs can be used to further enhance / improve the crosstalk protection duration. The appropriate scaling factor can be determined automatically by the LPs through various means, or it can be manually configured by the user during programming. Such a scaling factor can, for example, have a negative correlation between the distance between the LPs and the crosstalk protection duration. Additionally or alternatively, the scaling factor can have a negative correlation between the relative angle between the LPs and the crosstalk protection duration. That is, the crosstalk protection duration will decrease as the relative angle between the LPs increases, where zero angle is considered to exist between the LPs if they are parallel to each other. Once the scaling factor is determined, it can be multiplied by a crosstalk protection duration determined based on the amplitude of the pacing pulse transmitted by the LP in the remote chamber and / or based on the sensing detection threshold of the LP in the local chamber, for example, using one of the equations discussed above. In some embodiments, the scaling factor (sf) can have a value between 0 and 1, i.e., 0 ≤ sf ≤ 1.

[0161] In some embodiments, the scaling factor is selected by a user (clinician or physician) and programmed using an external device of the programmer type. In other embodiments, the controller of the LP (or external device, such as a programmer) can automatically determine the scaling factor to be used by the LP including the controller. For example, assuming a predetermined distance (e.g., 2 cm) and a predetermined angle (e.g., zero degrees) between LP 1 and LP 2, the crosstalk protection duration can be determined in one of the ways described above. A functional relationship between the amplitude sensed by LP 1 and the distance between LP 1 and LP 2 (at zero degrees or some other predetermined angle) is established in vitro for LP 2 pacing pulses with a known amplitude (e.g., 6 V amplitude and 0.4 ms pulse width), and this relationship is determined by and / or provided to the controller of LP 1. Then, after implantation of LP 1 and LP 2, LP 1 measures the in vivo sensed amplitude of detected crosstalk caused by pacing pulses with a known amplitude (e.g., 6 V pacing pulse amplitude and 0.4 ms pacing pulse width) delivered by LP 2. The controller of LP 1 can then compare the amplitude sensed inside the body with the amplitude sensed outside the body (measured when there is a known distance between LP 1 and LP 2, such as 2 cm, and the angle between LP 1 and LP 2 is zero degrees or some other known predetermined angle) to determine a ratio, which is then used to approximate the scaling factor to be used. The controller of LP 2 (or an external device) can also perform a similar process to determine the scaling factor for LP 2 to use.

[0162] A method according to certain embodiments of the present technology will now be outlined using the high-level flowchart of Figure 7A. This method is used in a multi-chamber leadless pacemaker (LP) system comprising a first leadless pacemaker (LP 1) and a second leadless pacemaker (LP 2), wherein LP 1 is configured to be implanted in or onto a first heart chamber of a patient's heart and to deliver pacing pulses to the first heart chamber, and LP 2 is configured to be implanted in or onto a second heart chamber of a patient's heart and to deliver pacing pulses to the second heart chamber. For example, LP 1 and LP 2 can be aLP 102a and vLP 102B, respectively. As another example, LP 1 and LP 2 can be vLP 102b and aLP 102A, respectively. Other variations are also possible and are within the scope of the embodiments described herein.

[0163] Referring to Figure 7A, step 702 involves obtaining information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second cardiac chamber and / or the sensitivity of the sensing circuitry of LP 1, which is configured to be used by LP 1 to detect the inherent depolarization of the first cardiac chamber. Still referring to Figure 7A, step 704 involves determining the crosstalk protection duration based on at least some of the information obtained at step 702.

[0164] According to some embodiments, when the information obtained at step 702 is about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, step 704 involves determining the crosstalk protection duration based on the amplitude of the pacing pulse, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration. The phrase "positive correlation," used herein to describe the relationship between two different variables, means that when one variable increases, the other variable also increases, and when one variable decreases, the other variable also decreases. Therefore, generally, the larger the amplitude of the pacing pulse (that LP 2 is configured to deliver to the second heart chamber), the longer the crosstalk protection period, and the lower the amplitude of the pacing pulse (that LP 2 is configured to deliver to the second heart chamber), the shorter the crosstalk protection period. The amplitude of the pacing pulse can be specified based on pulse amplitude and / or pulse width or pacing pulse charge (PPQ), where example equations for pacing pulse charge (PPQ) are provided above. Example equations for determining the crosstalk protection duration based on the amplitude of the pacing pulse and a sensing detection threshold of the sensing circuit are described above. In an embodiment, where there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, it can be determined that: if the pacing pulse has a first amplitude, the crosstalk protection duration has a first duration; and if the pacing pulse has a second amplitude greater than the first amplitude, the crosstalk protection duration has a second duration longer than the first duration. If the pacing pulse has a third amplitude less than the first amplitude, it can also be determined that the crosstalk protection duration has a third duration shorter than the first duration. As described above, and explained in more detail below, the sensitivity of the sensing circuit is not specified by a sensing detection threshold of the sensing circuit configured to detect the inherent depolarization of the first cardiac chamber, but can instead be specified by the gain of the sensing circuit configured to detect the inherent depolarization of the first cardiac chamber, in which case there is a positive correlation between the gain of the sensing circuit and the crosstalk protection duration.

[0165] According to some embodiments, when the information obtained at step 702 is information about the sensing detection threshold of the sensing circuit of LP1, which is configured to be used by LP1 to detect the inherent depolarization of the first heart chamber, step 704 involves determining the crosstalk protection duration based on the sensing detection threshold of the sensing circuit, such that there is a negative correlation between the sensing detection threshold of the sensing circuit and the crosstalk protection duration. The phrase "negative correlation," used herein to describe the relationship between two different variables, means that when one variable increases, the other decreases, and when one variable decreases, the other increases. Therefore, in general, the larger the sensing detection threshold of the sensing circuit of LP1 (configured by LP1 to detect the inherent depolarization of the first heart chamber), the shorter the crosstalk protection duration, and the lower the sensing detection threshold of the sensing circuit of LP1 (configured by LP1 to detect the inherent depolarization of the first heart chamber), the longer the crosstalk protection duration. In embodiments where there is a negative correlation between the sensing detection threshold of the sensing circuit of LP 1 and the crosstalk protection duration, if the sensing detection threshold of the sensing circuit of LP 1 has a first amplitude, it can be determined that the crosstalk protection duration has a first duration; and if the sensing detection threshold of the sensing circuit of LP 1 has a second amplitude greater than the first amplitude, it can be determined that the crosstalk protection duration has a second duration shorter than the first duration. It should be noted that when the LP is using the sensing detection threshold to detect the inherent depolarization of the cardiac chamber in which (or on which) the LP is implanted, the sensing detection threshold can also be more specifically referred to as the inherent depolarization detection threshold.

[0166] According to some embodiments, when the information obtained at step 702 is information about the gain of the sensing circuit of LP 1, this information is configured to be used by LP 1 to detect the inherent depolarization of the first cardiac chamber. Step 704 involves determining the crosstalk protection duration based on the gain of the sensing circuit, such that there is a positive correlation between the gain of the sensing circuit and the crosstalk protection duration. Therefore, generally, the greater the gain of the sensing circuit LP 1 (which is configured to be used by LP 1 to detect the inherent depolarization of the first cardiac chamber), the longer the crosstalk protection duration; and the lower the gain of the sensing circuit LP 1 (which is configured to be used by LP 1 to detect the inherent depolarization of the first cardiac chamber), the shorter the crosstalk protection duration.

[0167] In an embodiment, if there is a positive correlation between the gain of the sensing circuit (configured for detecting the inherent depolarization of the first cardiac chamber) and the crosstalk protection duration, it can be determined that if the gain circuit has a first gain, the crosstalk protection duration has a first duration, and if the gain circuit has a second gain greater than the first gain, the crosstalk protection duration has a second duration longer than the first duration. If the gain of the sensing circuit (configured for detecting the inherent depolarization of the first cardiac chamber) has a third gain less than the first gain, it can also be determined that the crosstalk protection duration has a third duration shorter than the first duration.

[0168] According to some embodiments, when the information obtained at step 702 includes information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, and information about the sensing detection threshold of the sensing circuit of LP 1 (which is configured by LP 1 to detect the inherent depolarization of the first heart chamber), the crosstalk protection duration determined at step 704 can be based on the amplitude of the pacing pulse and the sensing detection threshold of the sensing circuit. In such embodiments, there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration. Alternatively, in such embodiments, there is a negative correlation between sensitivity and the crosstalk protection duration (if sensitivity is specified by the sensing detection threshold of the gain circuit), or a positive correlation between sensitivity and the crosstalk protection duration (if sensitivity is specified by the gain of the sensing circuit). Example equations that can be used in such embodiments are shown in Equations 2 and 3 above. However, embodiments of the present technology are not limited to using such equations.

[0169] Referring again to Figure 7A, step 706 involves LP 1 monitoring for potential crosstalk that may be caused by LP 2 delivering one of the pacing pulses. This monitoring of potential crosstalk at step 706 can, for example, utilize the technology described in U.S. Patent No. 10,182,765 entitled "Systems and Methods for Classifying Signals of Interest in a Cardiac Rhythm Management Device". Figure 2-8 One of the techniques described in the description is used to perform this action, which is incorporated herein by reference as if fully elaborated herein. For example, refer to the initial discussion above. Figure 2 Assuming the sensing amplifier 132 of LP (in Figure 2If the signal is used to transmit a signal within a first frequency passband containing intrinsic cardiac activity (e.g., P wave and R wave), then the sensing amplifier 132 may also be referred to as intrinsic activity sensing amplifier 132, intrinsic activation sensing circuit, intrinsic depolarization sensing circuit, etc. To monitor for possible crosstalk, LP 1 may also include a separate crosstalk sensing circuit having a passband shifted to a frequency significantly higher than that of the intrinsic activity sensing amplifier 132, so that the crosstalk sensing circuit can better distinguish the relatively rapid rising and falling edges of crosstalk that may be caused by pacing pulses generated by another LP. Such crosstalk sensing circuit may be, for example, via LF receiver 120 or via... Figure 2 This is implemented using another sensing circuit not specifically shown. Using such a sensing circuit, LP 1, and more specifically its controller (e.g., 112), can classify the sensed signal being evaluated as potential crosstalk, where the sensed signal passes through a crosstalk sensing circuit. This is merely one example of the circuitry and techniques that LP 1 can use to perform potential crosstalk monitoring. In an embodiment, at step 706, LP 1 monitors for potential crosstalk that may be caused by LP 2 delivering one of the pacing pulses by determining whether the sensed signal is passed through the crosstalk sensing circuit, which is configured to pass signals falling within the crosstalk passband (which contains frequencies higher than the inherent depolarization frequency). At step 708, potential crosstalk is detected when the sensed signal passes through the crosstalk sensing circuit, and is not detected when the sensed signal does not pass through the crosstalk sensing circuit. The lower cutoff frequency of the crosstalk sensing circuit can be, for example, greater than or equal to 500 Hz. More generally, potential crosstalk can be detected at step 708 if the sensed signal has energy above a threshold within a specified frequency range where crosstalk is expected to exist. Using other circuits and / or techniques to monitor and detect potential crosstalk is also within the scope of the embodiments described herein.

[0170] In step 708, it is determined whether LP 1 has detected possible crosstalk. If the answer to the determination at step 708 is no, the process returns to step 706. If the answer to the determination at step 708 is yes, the process proceeds to step 710.

[0171] Step 710 involves LP 1 initiating crosstalk protection in response to the detection of potential crosstalk. In an embodiment, step 710 (or another step) includes initiating a crosstalk protection (CTP) timer to count down to (or count up to) the duration of crosstalk protection. In other words, the CTP timer is used to track how long crosstalk protection is performed such that the execution of crosstalk protection does not exceed the crosstalk protection duration (determined at step 704). In step 714, it is determined whether the crosstalk protection duration has expired. In an embodiment, step 714 (or another step) includes determining whether the CTP timer has expired. If the answer to the determination at step 714 is no, step 714 is repeated until the answer to the determination at step 714 is yes. When the answer to the determination at step 714 is yes, i.e., when the crosstalk protection duration has expired, the process proceeds to step 716. In step 716, LP 1 terminates (i.e., stops) the execution of crosstalk protection. In one embodiment, step 716 (or another step) includes resetting or reinitializing the CTP timer so that the CTP timer is ready to restart the next time potential crosstalk is prevented. In an alternative embodiment, the CTP timer reset or reinitialization occurs at step 710 before the CTP timer starts.

[0172] There are various ways in which LP 1 can perform crosstalk protection, which is initiated at step 710 and subsequently terminated at step 716 (after the crosstalk protection duration has expired). For example, crosstalk protection can be performed by blanking the sensing circuit (e.g., 132) used by LP 1 to monitor the inherent depolarization of the first cardiac chamber, ignoring any possible inherent depolarization detected by the sensing circuit using LP 1, disabling the sensing circuit used by LP 1 to monitor the inherent depolarization of the first cardiac chamber, ignoring any interruption generated in response to the sensing circuit being used to detect possible inherent depolarization, or disabling the generation of interruptions that can be generated in response to the sensing circuit detecting possible inherent depolarization. As used herein, the term interrupt refers to a signal that instructs the controller to stop what it is doing and instead perform another function. Possible inherent depolarization can be detected in response to the sensing signal exceeding the sensing detection threshold of the sensing circuit (e.g., 132). The reason for using the word "possibly" in the term or phrase "possibly inherent depolarization" is that inherent depolarization (detected in response to a sensing signal exceeding a sensing detection threshold of the sensing circuit) may not be true inherent depolarization, but rather a false positive detection of inherent depolarization. Those skilled in the art, upon reading this specification, will understand that crosstalk protection can be implemented in other ways, while remaining within the scope of the embodiments described herein.

[0173] In some embodiments, steps 702 and 704 are performed by an external programmer (e.g., 109) configured to communicate with LP1 and LP2, for example, using conducted communication, RF communication, and / or inductive communication, but not limited thereto. When steps 702 and 704 are performed by an external programmer, the external programmer can program the crosstalk protection duration into the memory or one or more registers of LP1 such that the crosstalk protection duration is available to LP1 when LP1 detects potential crosstalk that may be caused by LP2 delivering one of the pacing pulses. In other embodiments, steps 702 and 704 are performed by LP1 itself, or more specifically, by the controller of LP1 (e.g., 112). In some such embodiments, the controller of LP1 may receive information obtained at step 702 from its memory, from the external programmer (e.g., 109), and / or from another LP.

[0174] According to some embodiments, the controller (e.g., 112) of LP 1 is configured to dynamically adjust the sensitivity of the sensing circuit (e.g., 132) of LP 1, which LP 1 uses to detect the inherent depolarization of the first cardiac chamber in which (or on which) LP 1 is implanted. The controller may adjust the sensitivity of the sensing circuit for reasons such as reducing oversensing of inherent depolarization detection (where too many false positive inherent depolarization detections exist) or reducing undersensing of inherent depolarization detection (where too many false negative inherent depolarization detections exist), but is not limited to these.

[0175] In some such embodiments, when the controller (e.g., 112) adjusts the sensitivity of the sensing circuit, the controller also adjusts the crosstalk protection duration based on the adjusted sensitivity. More specifically, if the sensitivity is specified by a sensing detection threshold, the controller of LP1 determines the crosstalk protection duration such that there is a negative correlation between the sensing detection threshold and the crosstalk protection duration, and such that the controller of LP1 updates the crosstalk protection duration when it adjusts the sensing detection threshold of the sensing circuit of LP1. Alternatively, if the sensitivity is specified by the gain of the sensing circuit of LP1 (while the sensing detection threshold remains constant), the controller of LP1 determines the crosstalk protection duration such that there is a positive correlation between the gain and the crosstalk protection duration, and such that the controller of LP1 updates the crosstalk protection duration when it adjusts the gain of the sensing circuit of LP1.

[0176] According to some embodiments, the controller of LP2 is configured to dynamically adjust the amplitude of the pacing pulse that LP2 is configured to deliver to the second heart chamber, and when it does so, LP2 (via an i2i message) notifies the controller of LP1 of the adjustment to the amplitude of the pacing pulse. In some such embodiments, the controller of LP1 determines the crosstalk protection duration based on the amplitude of the pacing pulse that LP2 is configured to deliver to the second heart chamber, such that whenever the controller of LP1 is notified by LP2 of an adjustment to the amplitude of the pacing pulse, the controller of LP1 updates the crosstalk protection duration.

[0177] It is possible that when LP 1 detects potential crosstalk at the instance of step 708, the detected potential crosstalk is not actually crosstalk, but rather part of an actual message sent to LP 1 by another device. For example, it is possible that the detected potential crosstalk is actually a wake-up pulse of an implant-to-implant (i2i) message sent by LP 2 (or another implantable device, such as an S-ICD (e.g., 106)), or a wake-up pulse of a programmer-to-implant (p2i) message sent by an external programmer (e.g., 109). In the case where the detected potential crosstalk is not actually crosstalk, it would be beneficial if the crosstalk protection (which has been activated) terminated as quickly as possible, and certainly before the crosstalk protection duration expires, in order to reduce the likelihood that LP 1 misses the opportunity to detect the actual inherent depolarization of the first cardiac chamber in which (or on) LP 1 is implanted. A high-level flowchart in Figure 7B illustrates how this is done.

[0178] Referring to Figure 7B, steps 702-710 are the same as in Figure 7A and therefore need not be described again. As can be understood from Figure 7B, after LP 1 initiates crosstalk protection at step 710, at step 712, LP 1 determines whether the possible crosstalk (which was just detected at step 708) is actually part of a valid message sent by another device. If the answer to the determination at step 712 is yes, the flow proceeds to step 716, where LP 1 terminates the execution of crosstalk protection. If the answer to the determination at step 712 is no, the flow proceeds to step 714, and the method is performed in the manner discussed above with reference to Figure 7A. In yet another embodiment, if the answer to the determination at step 714 is no, the flow returns to step 712 instead of returning to step 714. According to some embodiments, LP 1 can determine whether the possible crosstalk (detected in step 708) is actually part of a valid message sent by another device (in step 712) by analyzing the received signal within the message window after the possible crosstalk is detected (in step 708). For example, refer to... Figure 2Because potential crosstalk could actually be a wake-up pulse for a valid message, in response to the detection of potential crosstalk (e.g., via LF receiver 120), HF receiver 122 can be enabled and used to sense the signal within the message window (after the potential crosstalk is detected), and the signal output from HF receiver 122 can be provided to controller 112, which can determine whether a valid message has been received by determining whether the pulse within the message window is the pulse expected to be included in a valid message. For example, if a message is received within the expected time window after the LF wake-up pulse, and it includes a valid preamble / tag code that passes a CRC check (if the CRC is included in the message), then the message can be considered valid. Other variations are also possible and are within the embodiments described herein.

[0179] It should be understood that when an LP (e.g., LP 1) performs certain steps or functions, such steps are typically performed by or under the control of the LP's controller (e.g., 112), which may contain, but is not limited to, a microprocessor and / or a state machine. Similarly, when a programmer (e.g., 109) or other external device performs certain steps or functions, these steps are typically performed by or under the control of the external device's controller.

[0180] Figure 8 A block diagram of one embodiment of an IMD (e.g., LP or ICD) 801 implanted in a patient as part of an implantable cardiac system, according to certain embodiments herein, is shown. Optionally, the IMD 801 can provide full-function cardiac resynchronization therapy. Alternatively, the IMD 801 can be implemented with a reduced set of functions and components. For example, the IMD can be implemented without ventricular sensing and pacing.

[0181] The IMD 801 has a housing 800 for holding electronic / computing components. The housing 800 (which is commonly referred to as a “can,” “shell,” “encapsulation,” or “shell electrode”) can be programmably selected to serve as a return electrode for certain stimulation modes. The housing 800 may also include connectors (not shown) with multiple terminals 802, 804, 806, 808, and 810. These terminals can be connected to electrodes located at various sites on the housing 800 or elsewhere within and around the heart. The IMD 801 includes a programmable microcontroller 820, which controls various operations of the IMD 801, including cardiac monitoring and stimulation therapy. The microcontroller 820 includes a microprocessor (or equivalent control circuitry), RAM and / or ROM memory, logic and timing circuitry, state machine circuitry, and I / O circuitry.

[0182] The IMD 801 also includes a first pulse generator 822 that generates stimulation pulses for delivery by one or more electrodes coupled thereto. The pulse generator 822 is controlled by a microcontroller 820 via a control signal 824. The pulse generator 822 can be coupled to one or more select electrodes via an electrode configuration switch 826, which includes multiple switches for connecting a desired electrode to appropriate I / O circuitry, thereby facilitating electrode programmability. The switch 826 is controlled by a control signal 828 from the microcontroller 820.

[0183] exist Figure 8 In one embodiment, a single pulse generator 822 is shown. Alternatively, the IMD may include multiple pulse generators, similar to pulse generator 822, wherein each pulse generator is coupled to one or more electrodes and controlled by microcontroller 820 to deliver selected stimulation pulses to the corresponding one or more electrodes.

[0184] The microcontroller 820 is shown to include timing control circuitry 832 for controlling the timing of stimulation pulses (e.g., pacing rate, atrioventricular (AV) delay, atrial (AA) conduction delay, or ventricular (VV) conduction delay, etc.). The timing control circuitry 832 can also be used for timing refractory periods, blanking intervals, noise detection windows, evoked response windows, alarm intervals, marker channel timing, etc. The microcontroller 820 also has an arrhythmia detector 834 for detecting arrhythmic conditions. The microcontroller 820 is also shown to include a crosstalk protection module 836, which can be used to determine the duration of crosstalk protection using embodiments of the technology described herein, and / or can be used to detect potential crosstalk. Although not shown, the microcontroller 820 may also include other dedicated circuitry and / or firmware / software components to assist in monitoring various conditions of the patient's heart and managing pacing therapy.

[0185] The IMD 801 is further equipped with a communication modem (modulator / demodulator) 840 to enable wireless communication with other devices. The modem 840 may include one or more transmitters and two or more receivers, as described herein. Figure 2 The modem 840 is discussed in one embodiment. It may use low-frequency or high-frequency modulation. As an example, the modem 840 may transmit I2I messages and other signals via conductive communication between a pair of electrodes. The modem 840 may alternatively or additionally be used to provide RF communication and / or inductive communication. The modem 840 may be implemented in hardware as part of a microcontroller 820, or as software / firmware instructions programmed into and executed by the microcontroller 820. Alternatively, the modem 840 may reside separately from the microcontroller as a standalone component.

[0186] The IMD 801 includes sensing circuitry 844, selectively coupled via switch 826 to one or more electrodes performing sensing operations to detect the presence of cardiac activity in the right ventricle of the heart. Sensing circuitry 844 may include a dedicated sensing amplifier, a multiplexed amplifier, or a shared amplifier. It may also employ one or more low-power precision amplifiers with programmable gain and / or automatic gain control, bandpass filtering, and threshold detection circuitry to selectively sense cardiac signals of interest. Automatic gain control enables the unit to sense the low-amplitude signal characteristics of atrial fibrillation. Switch 826 determines the sensing polarity of the cardiac signal by selectively closing an appropriate switch. In this way, clinicians can program the sensing polarity independently of the stimulus polarity.

[0187] The output of sensing circuit 844 is connected to microcontroller 820, which in turn triggers or disables pulse generator 822 in response to the presence or absence of cardiac activity. Sensing circuit 844 receives control signal 846 from microcontroller 820 for controlling the timing of gain, threshold, polarization charge removal circuit (not shown), and any blocking circuits (not shown) coupled to the input of sensing circuit.

[0188] exist Figure 8 In the embodiments described, a single sensing circuit 844 is illustrated. Alternatively, the IMD may include multiple sensing circuits similar to sensing circuit 844, wherein each sensing circuit is coupled to one or more electrodes and controlled by microcontroller 820 to sense electrical activity detected at the corresponding one or more electrodes. Sensing circuit 844 may operate in a unipolar sensing configuration or a bipolar sensing configuration.

[0189] IMD 801 further includes an analog-to-digital (A / D) data acquisition system (DAS) 850 coupled to one or more electrodes via a switch 826 to sample cardiac signals across any desired pair of electrodes. The data acquisition system 850 is configured to acquire intracardiac electrogram signals, convert raw analog data into digital data, and store the digital data for later processing and / or telemetry transmission to an external device 109 (e.g., a programmer, local transceiver, or diagnostic system analyzer). The data acquisition system 850 is controlled by control signals 856 from a microcontroller 820.

[0190] The microcontroller 820 is coupled to the memory 860 via a suitable data / address bus. Programmable operating parameters used by the microcontroller 820 are stored in the memory 860 and are used to customize the operation of the IMD 801 to suit the needs of a specific patient. These operating parameters define, for example, pacing pulse amplitude, pulse duration, electrode polarity, rate, sensitivity (e.g., sensing detection threshold or gain), automatic characteristics, arrhythmia detection criteria, and the amplitude, waveform, and vector of each electrical shock pulse to be delivered to the patient's heart at each corresponding treatment level.

[0191] The operating parameters of the IMD 801 can be non-invasively programmed into the memory 860 via a telemetry circuit 864 that communicates telemetryally with the external device 109 via a communication link 866. The telemetry circuit 864 allows the transmission of intracardiac electrograms and status information (containing in the microcontroller 820 or the memory 860) related to the operation of the IMD 801 to the external device 109 via the communication link 866.

[0192] The IMD 801 may also include a magnet detection circuit (not shown) coupled to the microcontroller 820 to detect when a magnet is placed on the cell. Clinicians can use the magnet to perform various test functions of the IMD 801 and / or signal the microcontroller 820 that the external device 109 is in place, and to receive or send data to the microcontroller 820 via the telemetry circuit 864.

[0193] The IMD 801 may also include one or more physiological sensors 870. These sensors are often referred to as “rate-responsive” sensors because they are typically used to adjust the pacing stimulation rate based on the patient’s exercise status. However, the physiological sensors 870 can be further used to detect changes in cardiac output, changes in the physiological condition of the heart, or diurnal variations in activity (e.g., detecting sleep and wakefulness). Signals generated by the physiological sensors 870 are passed to a microcontroller 820 for analysis. The microcontroller 820 responds by adjusting various pacing parameters that manage atrial and ventricular pacing pulses, such as rate, AV delay, VV delay, etc. Although shown as being included within the IMD 801, one or more physiological sensors 870 may be external to the IMD 801 but still implanted in or carried by the patient. Examples of physiological sensors may include sensors that sense respiratory rate, blood pH, ventricular gradient, activity, position / posture, minute ventilation (MV), etc.

[0194] Battery 872 provides operating power to all components in IMD 801. Battery 872 is capable of long-term operation with low current consumption and can provide high-current pulses (for capacitor charging) when the patient requires a shock pulse (e.g., exceeding 2 A at a voltage above 2 V for a period of 10 seconds or longer). Battery 872 also ideally has predictable discharge characteristics, allowing for the detection of selective replacement times. As an example, IMD 801 employs a lithium / silver vanadium oxide battery.

[0195] The IMD 801 further includes impedance measurement circuitry 874, which can be used for a variety of purposes, including: monitoring lead impedance during the acute and chronic phases for proper lead positioning or displacement; detecting an operable electrode and automatically switching to an operable pair if displacement occurs; measuring respiratory rate or minute ventilation; measuring chest impedance to determine the shock threshold; detecting when the device has been implanted; measuring stroke volume; and detecting the opening of heart valves; and so on. Impedance measurement circuitry 874 is coupled to switch 826, allowing the use of any desired electrode. In this embodiment, the IMD 801 also includes shock circuitry 880 coupled to microcontroller 820 via data / address bus 882.

[0196] Figure 9 Example components of an example external device 109 for communicating with and / or programming the LP 102 or other types of IMDs are shown. More generally, the external device 109 may allow a physician or other authorized user to program the operation of the LP. Furthermore, the external device 109 may be able to cause the LP 102 to perform functions necessary to accomplish certain methods of the present invention.

[0197] Now, through reference Figure 9 Considering the components of external device 109, the operation of external device 109 can be controlled by CPU 902. CPU 902 can be a generally programmable microprocessor or microcontroller, or it can be a special-purpose processing device, such as an application-specific integrated circuit (ASIC). Software instructions to be executed by the CPU can be accessed via internal bus 904 from read-only memory (ROM) 906 and random access memory (RAM) 930. Additional software can be accessed from hard disk drive 908, floppy disk drive 910, and CD ROM drive 912, or other suitable permanent mass storage devices. Depending on the specific implementation, the CPU retrieves the Basic Input / Output System (BIOS) from the ROM upon power-up. Based on the instructions provided in the BIOS, the CPU "boots up" the entire system using sophisticated computer processing techniques.

[0198] Once activated, the CPU displays a menu of programming options to the user via the LCD display 914 or another suitable computer display device. For this purpose, the CPU may display, for example, a menu of specific programming parameters for the LP 102 to be programmed, or a menu of diagnostic data types to be retrieved and displayed. In response, the physician inputs various commands via the touchscreen 916 overlaid on the LCD display 914 or via a standard keyboard 918 supplemented with additional custom keys 920 (such as an Emergency VVI (EVVI) key). The EVVI key sets the LP 102 to a safe WVI mode with high pacing output. This ensures life-sustaining pacing operation in almost all situations, but it is never desirable to keep the cardiac stimulation device 100 in IMV mode at all times.

[0199] Typically, the physician initially controls the external device 109 to retrieve data stored in one or more LPs 102. For this purpose, the CPU 902 sends appropriate signals to the telemetry circuitry 922, which provides components for directly interfaced with the LPs 102. The telemetry subsystem 922 may include its own separate CPU 924 for coordinating the operation of the telemetry subsystem 922. The main CPU 902 of the external device 109 communicates with the telemetry subsystem CPU 924 via an internal bus 904. The telemetry subsystem 922 further includes telemetry circuitry 926 for communicating with the LPs(one or more). The telemetry subsystem 922 may utilize one or more types of communication technologies to communicate with the LPs(one or more), such as, but not limited to, conducted communication, RF communication, or inductive communication. Patient and device diagnostic data stored in the LPs(one or more) 102 can be transmitted to the external device 109. Furthermore, one or more LPs 102 may be instructed to execute the electrode algorithm of the present invention, details of which are provided above. According to certain embodiments of the present technology, CPU 902 may include a crosstalk protection duration module 950 for determining the duration of crosstalk protection.

[0200] External device 109 may also include a network interface card (“NIC”) 960 to allow data transfer to and from other computer systems via router 962 and wide area network (“WAN”) 964. Alternatively, external device 109 may include a modem for communication via the public switched telephone network (PSTN).

[0201] Depending on the implementation, the modem can be directly connected to the internal bus 904, or it can be connected to the internal bus via a parallel port 940 or a serial port 942. Data transmitted from other computer systems may include, for example, data about prescriptions, medications administered, or sold to patients.

[0202] External device 109 receives data from LP 102, including parameters indicating the current programming state of LP 102. External device 109 may also receive electrograms (EGMs), samples of them, and / or dates indicating their occurrence from one or more LPs 102. Under the physician's control, external device 109 displays the current programming parameters and allows the physician to reprogram them. To do this, the physician enters appropriate commands via any of the aforementioned input devices, and under the control of CPU 902, the programming commands are translated into specific programming parameters for transmission to LP 102, thereby reprogramming LP 102. Before reprogramming specific parameters, the physician can control the external programmer to display any or all data retrieved from one or more LPs 102, including ECG displays, displays of candidate electrodes as cathodes and / or anodes, and statistical patient information. Any or all information displayed by external device 109 can also be printed using printer 936.

[0203] Includes a speaker 944 for providing audible audio to the user, such as a warning beep in case a doctor provides incorrect input. The telemetry subsystem 922 may additionally include input / output circuitry 946 for controlling the transmission of analog output signals, such as ECG signals output to an ECG machine or chart recorder. Other peripheral devices may also be connected to external device 109 via parallel port 940 or serial port 942. Although one of each port is shown, multiple input / output (IO) ports may be provided.

[0204] Using the external device 109 configured as shown in the figure, doctors or other authorized users can retrieve, process, and display a wide range of information received from LP(one or more) 102, and reprogram LP(one or more) 102 if needed. This article is about Figure 9 The description provided is intended only to provide an operational overview of example external device 109 and is not intended to describe every feature of the device's hardware and software in detail, nor to provide an exhaustive list of functions performed by the device. According to one embodiment, the controller of external device 109 (e.g., 902) is configured to obtain information about one or more of the following: the sensitivity of a sensing circuit of a first LP (LP 1), which is configured by LP 1 to detect inherent depolarization of a first cardiac chamber implanted with LP 1, or the amplitude of a pacing pulse delivered by a second LP (LP 2) to a second cardiac chamber implanted with LP 2. Additionally, the controller of external device 109 (e.g., 902) is configured to determine a crosstalk protection duration based on at least some information, wherein the determined crosstalk protection duration is used by LP 1 to perform crosstalk protection during the crosstalk protection duration in response to LP 1 detecting potential crosstalk that may be caused by one of the pacing pulses delivered by LP 2.

[0205] One aspect of the embodiments relates to a system for or including a first leadless pacemaker (LP 1) and a second leadless pacemaker (LP 2), wherein LP 1 is configured to be implanted in or on a first heart chamber of a patient's heart and to deliver pacing pulses to the first heart chamber, and LP 2 is configured to be implanted in or on a second heart chamber of the patient's heart and to deliver pacing pulses to the second heart chamber. The system includes a controller configured to acquire information about one or more of the following: the amplitude of the pacing pulses that LP 2 is configured to deliver to the second heart chamber; or the sensitivity of a sensing circuit of LP 1, the sensing circuit being configured to be used by LP 1 to detect inherent depolarization of the first heart chamber. The controller is also configured to determine a crosstalk protection duration based on at least some information, wherein the determined crosstalk protection duration is used by LP 1 to perform crosstalk protection during the crosstalk protection duration in response to LP 1 detecting possible crosstalk that may be caused by one of the pacing pulses delivered by LP 2.

[0206] One aspect of the embodiments relates to a system including a first leadless pacemaker (LP 1) configured to be implanted in or on a first cardiac chamber of a patient's heart, and including: a pulse generator configured to deliver pacing pulses to the first cardiac chamber; and sensing circuitry configured to detect inherent depolarization of the first cardiac chamber. The system also includes a second leadless pacemaker (LP 2) configured to be implanted in or on a second cardiac chamber of a patient's heart, and including: a pulse generator configured to deliver pacing pulses to the second cardiac chamber; and sensing circuitry configured to detect inherent depolarization of the second cardiac chamber. The system further includes a controller configured to: obtain information regarding one or more of the amplitude of pacing pulses delivered by the pulse generator of LP 2 to the second cardiac chamber or the sensitivity of the sensing circuitry of LP 1, the sensing circuitry of LP 1 being configured by LP 1 to detect inherent depolarization of the first cardiac chamber; and determine a crosstalk protection duration based on at least some of the information. In other words, the controller can be configured to determine the length of the crosstalk protection duration based on information about the amplitude of the pacing pulses that the pulse generator of LP 2 is configured to deliver to the second cardiac chamber and / or based on information about the sensitivity of the sensing circuitry of LP 1, which is configured by LP 1 to detect the inherent depolarization of the first cardiac chamber. In some such embodiments, LP 1 is configured to perform crosstalk protection during the crosstalk protection duration in response to LP 1 detecting possible crosstalk that may be caused by the pulse generator of LP 2 delivering one of the pacing pulses.

[0207] In one embodiment, the controller is configured to: obtain information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second cardiac chamber; and determine a crosstalk protection duration based on the amplitude of the pacing pulse, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration. In another embodiment, when the controller is configured to determine the crosstalk protection duration based on the amplitude of the pacing pulse such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, the controller is configured to: if the pacing pulse has a first amplitude, determine that the crosstalk protection duration has a first duration; and if the pacing pulse has a second amplitude greater than the first amplitude, determine that the crosstalk protection duration has a second duration longer than the first duration.

[0208] In an embodiment, the controller is configured to obtain information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber by obtaining information about at least one of the pulse amplitude or pulse width of the pacing pulse that LP 2 is configured to deliver to the second heart chamber.

[0209] In an embodiment, the controller is configured to obtain information about the sensitivity of the sensing circuitry of LP1. In some such embodiments, the sensitivity of the sensing circuitry of LP1 is specified by a sensing detection threshold of the sensing circuitry of LP1, which is configured to be used by LP1 to detect the inherent depolarization of the first cardiac chamber, and the controller is configured to determine a crosstalk protection duration based on the sensing detection threshold of the sensing circuitry, such that there is a negative correlation between the sensing detection threshold of the sensing circuitry and the crosstalk protection duration. In one embodiment, wherein the controller is configured to determine the crosstalk protection duration based on the sensing detection threshold of the sensing circuitry of LP1, such that there is a negative correlation between the sensing detection threshold of the sensing circuitry of LP1 and the crosstalk protection duration, the controller is configured to: determine that the crosstalk protection duration has a first duration if the sensing detection threshold of the sensing circuitry of LP1 has a first amplitude, and determine that the crosstalk protection duration has a second duration shorter than the first duration if the sensing detection threshold of the sensing circuitry of LP1 has a second amplitude greater than the first amplitude. Alternatively, the sensitivity of the sensing circuit of LP 1 is specified by the gain of the sensing circuit of LP 1, which is configured to be used by LP 1 to detect the inherent depolarization of the first cardiac chamber, and the controller is configured to determine the crosstalk protection duration based on the gain of the sensing circuit, such that there is a positive correlation between the gain of the sensing circuit and the crosstalk protection duration. In one embodiment, when the controller is configured to determine the crosstalk protection duration based on the gain of the sensing circuit of LP 1 (which is configured to detect the inherent depolarization of the first cardiac chamber), such that there is a positive correlation between the gain of the sensing circuit (which is configured to detect the inherent depolarization of the first cardiac chamber) and the crosstalk protection duration, the controller is configured to determine that the crosstalk protection duration has a first duration if the gain circuit has a first gain, and to determine that the crosstalk protection duration has a second duration longer than the first duration if the gain circuit has a second gain greater than the first gain. The controller can also be configured to determine that the crosstalk protection duration has a third duration shorter than the first duration if the gain of the sensing circuit (which is configured to detect the inherent depolarization of the first cardiac chamber) has a third gain less than the first gain.

[0210] In an embodiment, the controller is configured to: obtain information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, and obtain information about the sensitivity of the sensing circuit of LP 1, which is configured to be used by LP 1 to detect the inherent depolarization of the first heart chamber; and determine the duration of crosstalk protection based on the amplitude of the pacing pulse and the sensitivity of the sensing circuit.

[0211] In an embodiment, the controller is configured to determine the crosstalk protection duration based on at least one of the relevant scaling factors, namely the distance between LP1 and LP2 or the angles of LP1 and LP2 relative to each other.

[0212] In one embodiment, the system includes a controller of LP 1, wherein the controller of LP 1 is configured to: monitor and detect possible crosstalk that may be caused by one of the pacing pulses delivered by LP 2; and in response to detecting possible crosstalk that may be caused by LP 2 delivering one of the pacing pulses, initiate the execution of crosstalk protection for the duration of crosstalk protection.

[0213] In an embodiment, the controller of LP1 is configured to: dynamically adjust the sensitivity of the sensing circuit of LP1; and determine the crosstalk protection duration based on the sensitivity, such that when the controller of LP1 adjusts the sensitivity of the sensing circuit of LP1, the controller of LP1 updates the crosstalk protection duration.

[0214] In an embodiment, the controller of LP 2 is configured to dynamically adjust the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, and to notify the controller of LP 1 of the adjustment to the amplitude of the pacing pulse; and the controller of LP 1 is configured to determine the crosstalk protection duration based on the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, and to update the crosstalk protection duration in response to the controller of LP 1 being notified of the adjustment to the amplitude of the pacing pulse.

[0215] In one embodiment, the system includes a non-implantable programmer that includes a controller configured to determine the crosstalk protection duration and is configured to communicate with LP 1 and LP 2 (directly or through an intermediary such as another IMD), wherein the non-implantable programmer is configured to program the crosstalk protection duration into the memory or one or more registers of LP 1 such that the crosstalk protection duration is available to LP 1 when LP 1 detects potential crosstalk that may be caused by one of the pacing pulses transmitted by LP 2.

[0216] In an embodiment, the system includes a controller portion of LP 1, wherein the controller of LP 1 is configured to provide crosstalk protection during the crosstalk protection duration by causing at least one of the following: blanking the sensing circuitry of LP 1 during the crosstalk protection duration; ignoring any possible inherent depolarization detected by the sensing circuitry of LP 1 during the crosstalk protection duration; disabling the sensing circuitry of LP 1 during the crosstalk protection duration; ignoring any interruptions generated by the sensing circuitry in response to detecting possible inherent depolarization during the crosstalk protection duration; and disabling the generation of interruptions that may be generated in response to the sensing circuitry detecting inherent depolarization during the crosstalk protection duration.

[0217] In one embodiment, the system includes a portion of LP 1 containing a controller, wherein the controller of LP 1 is configured to: determine whether a detected potential crosstalk is part of a valid message sent by another device; and, in response to determining that the detected potential crosstalk is part of a valid message sent by another device, terminate crosstalk protection for the remainder of the crosstalk protection duration.

[0218] In an embodiment, LP 1 is configured to provide crosstalk protection during the crosstalk protection duration by causing at least one of the following: blanking the sensing circuit of LP 1 during the crosstalk protection duration; ignoring any possible inherent depolarization detected by the sensing circuit of LP 1 during the crosstalk protection duration; disabling the sensing circuit of LP 1 during the crosstalk protection duration; ignoring any interruption generated by the sensing circuit in response to detecting a possible inherent depolarization during the crosstalk protection duration; or prohibiting the generation of interruptions that could be generated in response to the sensing circuit detecting inherent depolarization during the crosstalk protection duration.

[0219] Another aspect of the embodiments relates to a leadless pacemaker configured to communicate with another leadless pacemaker, wherein the leadless pacemaker is configured to be implanted in or onto a first cardiac chamber of a patient's heart and to deliver pacing pulses to the first cardiac chamber, and the other leadless pacemaker is configured to be implanted in or onto a second cardiac chamber of the patient's heart and to deliver pacing pulses to the second cardiac chamber. The leadless pacemaker includes sensing circuitry and a controller. The sensing circuitry is configured to detect inherent depolarization of the first cardiac chamber. The controller is configured to obtain information about one or more of the following: the amplitude of the pacing pulses delivered by the other leadless pacemaker to the second cardiac chamber, or the sensitivity of the sensing circuitry. The controller is also configured to: determine a crosstalk protection duration based on at least some information; monitor for possible crosstalk that may be caused by the other leadless pacemaker delivering one of the pacing pulses; and, in response to detecting possible crosstalk that may be caused by the other leadless pacemaker delivering one of the pacing pulses, perform crosstalk protection during the crosstalk protection duration.

[0220] In one embodiment, the controller is configured to obtain information about the amplitude of a pacing pulse that is configured to be delivered to a second heart chamber by another leadless pacemaker, and based on this, to determine a crosstalk protection duration such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration.

[0221] In one embodiment, the controller is configured to: obtain information about a sensing detection threshold of the sensing circuit, and determine a crosstalk protection duration based on the sensing detection threshold of the sensing circuit, such that there is a negative correlation between the sensing detection threshold of the sensing circuit and the crosstalk protection duration; or obtain information about the gain of the sensing circuit, and determine the crosstalk protection duration based on the gain of the sensing circuit, such that there is a positive correlation between the gain of the sensing circuit and the crosstalk protection duration.

[0222] In one embodiment, the controller is configured to: obtain information about the amplitude of a pacing pulse for which another leadless pacemaker is configured to deliver to a second heart chamber; obtain information about the sensitivity of the sensing circuit; and determine the duration of crosstalk protection based on the amplitude of the pacing pulse and the sensitivity of the sensing circuit.

[0223] In one embodiment, the controller is configured to also determine the duration of the crosstalk protection based on a scaling factor, which is related to at least one of the distance between the leadless pacemaker and the other leadless pacemaker, or the angle between the leadless pacemaker and the other leadless pacemaker relative to each other.

[0224] In one embodiment, the controller is configured to: dynamically adjust the sensitivity of the sensing circuit; and determine the crosstalk protection duration based on the sensitivity of the sensing circuit, such that the crosstalk protection duration is updated when the sensitivity of the sensing circuit is adjusted.

[0225] In one embodiment, the controller is configured to: determine the crosstalk protection duration based on the amplitude of the pacing pulse of another leadless pacemaker configured to deliver to the second heart chamber, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, and to update the crosstalk protection duration in response to being notified of an adjustment to the amplitude of the pacing pulse of another leadless pacemaker configured to deliver to the second heart chamber.

[0226] In an embodiment, the controller is configured to provide crosstalk protection during the crosstalk protection duration by causing at least one of the following: blanking the sensing circuit during the crosstalk protection duration; ignoring any possible inherent depolarization detected by the sensing circuit during the crosstalk protection duration; disabling the sensing circuit during the crosstalk protection duration; ignoring any interruption generated by the sensing circuit in response to detecting a possible inherent depolarization during the crosstalk protection duration; or preventing the generation of interruptions that could be generated in response to the sensing circuit detecting inherent depolarization during the crosstalk protection duration.

[0227] In one embodiment, the controller is configured to: determine whether the detected potential crosstalk is part of a valid message sent by another device; and, in response to determining that the detected potential crosstalk is part of a valid message sent by another device, terminate the crosstalk protection for the remaining time of the crosstalk protection duration.

[0228] Another aspect of the embodiments relates to a method for a dual-chamber leadless pacemaker (LP) system, the system including a first leadless pacemaker (LP 1) and a second leadless pacemaker (LP 2), wherein LP 1 is configured to be implanted in or onto a first cardiac chamber of a patient's heart and to deliver pacing pulses to the first cardiac chamber, and LP 2 is configured to be implanted in or onto a second cardiac chamber of the patient's heart and to deliver pacing pulses to the second cardiac chamber. The method includes obtaining information about one or more of: the amplitude of the pacing pulses delivered to the second cardiac chamber by LP 2; or the sensitivity of a sensing circuit of LP 1, the sensing circuit being configured to be used by LP 1 to detect inherent depolarization of the first cardiac chamber. The method also includes determining a crosstalk protection duration based on at least some of the information. The method further includes LP 1 monitoring and detecting potential crosstalk that may be caused by LP 2 delivering one of the pacing pulses, and LP 1 initiating crosstalk protection for the duration of the crosstalk protection in response to detecting potential crosstalk that may be caused by LP 2 delivering one of the pacing pulses.

[0229] In one embodiment, obtaining information includes obtaining information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber; and determining the crosstalk protection duration based on the amplitude of the pacing pulse, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration. In one embodiment, obtaining information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber includes obtaining information about at least one of the pulse amplitude or pulse width of the pacing pulse that LP 2 is configured to deliver to the second heart chamber.

[0230] In embodiments, obtaining information includes obtaining information about the sensitivity of the sensing circuitry of LP1. In some such embodiments, the sensitivity of the sensing circuitry of LP1 is specified by a sensing detection threshold of the sensing circuitry of LP1, which is configured to be used by LP1 to detect the inherent depolarization of the first cardiac chamber, and the crosstalk protection duration is determined based on the sensing detection threshold of the sensing circuitry such that there is a negative correlation between the sensing detection threshold of the sensing circuitry and the crosstalk protection duration. In one embodiment, wherein the controller is configured to determine the crosstalk protection duration based on the sensing detection threshold of the sensing circuitry of LP1, such that there is a negative correlation between the sensing detection threshold of the sensing circuitry of LP1 and the crosstalk protection duration, the controller is configured to: determine that the crosstalk protection duration has a first duration if the sensing detection threshold of the sensing circuitry of LP1 has a first amplitude, and determine that the crosstalk protection duration has a second duration shorter than the first duration if the sensing detection threshold of the sensing circuitry of LP1 has a second amplitude greater than the first amplitude. Alternatively, the sensitivity of the sensing circuit of LP 1 is specified by the gain of the sensing circuit of LP 1, which is configured by LP 1 to detect the inherent depolarization of the first cardiac chamber, and the crosstalk protection duration is determined based on the gain of the sensing circuit such that there is a positive correlation between the gain of the sensing circuit and the crosstalk protection duration.

[0231] In one embodiment, obtaining information includes obtaining information about the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, and obtaining information about the sensitivity of the sensing circuit of LP 1, which is configured to be used by LP 1 to detect the inherent depolarization of the first heart chamber; and determining the crosstalk protection duration based on the amplitude of the pacing pulse and the sensitivity of the sensing circuit.

[0232] In one embodiment, determining the duration of crosstalk protection is also based on at least one of the relevant scaling factors: the distance between LP1 and LP2 or the angles of LP1 and LP2 relative to each other.

[0233] In this embodiment, the determination of the crosstalk protection duration is performed by the controller of LP 1.

[0234] In an embodiment, the controller of LP1 is configured to dynamically adjust the sensitivity of the sensing circuit of LP1; and to determine the crosstalk protection duration based on the sensitivity, such that when the controller of LP1 adjusts the sensitivity of the sensing circuit of LP1, the controller of LP1 updates the crosstalk protection duration.

[0235] In an embodiment, the controller of LP 2 is configured to dynamically adjust the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, and notify the controller of LP 1 of the adjustment to the amplitude of the pacing pulse; and determine the crosstalk protection duration based on the amplitude of the pacing pulse that LP 2 is configured to deliver to the second heart chamber, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, and such that the controller of LP 1 updates the crosstalk protection duration in response to the adjustment to the amplitude of the pacing pulse made by LP 2.

[0236] In an embodiment, obtaining information and determining the crosstalk protection duration is performed by a non-implantable programmer; and the method further includes the non-implantable programmer programming the crosstalk protection duration into the memory or one or more registers of the LP 1 such that the crosstalk protection duration is available to the LP 1 when the LP 1 detects possible crosstalk (which may be caused by one of the pacing pulses delivered by the LP 2).

[0237] In an embodiment, providing crosstalk protection during the crosstalk protection duration includes at least one of the following: blanking the sensing circuit of LP 1 during the crosstalk protection duration; ignoring any possible inherent depolarization detected by the sensing circuit of LP 1 during the crosstalk protection duration; disabling the sensing circuit of LP 1 during the crosstalk protection duration; ignoring any interruption generated by the sensing circuit in response to detecting possible inherent depolarization during the crosstalk protection duration; or disabling the generation of interruptions that may be generated in response to the sensing circuit detecting inherent depolarization during the crosstalk protection duration.

[0238] In an embodiment, the method further includes determining that the detected potential crosstalk is part of a valid message sent by another device, and in response, terminating the crosstalk protection for the remainder of the crosstalk protection duration.

[0239] Embodiments of the present technology have been described above using functional building blocks that illustrate the performance of specified functions and their relationships. For ease of description, the boundaries of these functional building blocks are generally defined herein. Alternative boundaries can be defined as long as the specified functions and their relationships are performed appropriately. Therefore, any such alternative boundaries are within the scope and spirit of the claimed invention. For example, some steps shown in Figures 7A and 7B can be combined or separated. Some steps shown in Figures 7A and 7B can also be rearranged. For another example, the steps can be changed... Figure 2 , Figure 8 and Figure 9 The boundaries of some blocks are shown.

[0240] It should be understood that the subject matter described herein is not limited in its application to the details of the construction and the arrangement of components set forth in the description or shown in the accompanying drawings. The subject matter described herein can have other embodiments and can be practiced or performed in various ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting. The use of “comprising,” “including,” or “having,” and variations thereof herein is intended to cover the items listed thereafter and their equivalents, as well as additional items. Furthermore, it should be noted that, unless otherwise stated, the term “based on” as used herein should be interpreted as meaning at least partially based on, implying the existence of one or more additional factors upon which the decision or similar decision is based. For example, if a decision is based on the results of a comparison, then in addition to being based on the results of the comparison, the decision may also be based on one or more other factors.

[0241] It should be understood that the above description is intended to be illustrative and not restrictive. For example, the above embodiments (and / or aspects thereof) can be used in combination with each other. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of embodiments of the present technology without departing from the scope of the present technology. While the dimensions and types of materials and coatings described herein are intended to define parameters of embodiments of the present technology, they are by no means restrictive but rather exemplary embodiments. Many other embodiments will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of embodiments of the present technology should be determined by reference to the appended claims and the full scope of their equivalents. In the appended claims, the terms “comprising” and “wherein” are used as concise English equivalents of the corresponding terms “including” and “wherein”. Furthermore, in the following claims, the terms “first,” “second,” and “third,” etc., are used merely as denoting marks and are not intended to impose numerical requirements on their objects. Moreover, the limitations of the appended claims are not written in a means-plus-function format and are not intended to be interpreted based on 35 U.S.SC §112(f), unless and until such a claim expressly uses the phrase “means for…” followed by a functional statement without further structure.

Claims

1. A system for use with or comprising a first leadless pacemaker (LP1) and a second leadless pacemaker (LP2), wherein, The LP1 is configured to be implanted in or on a first heart chamber of a patient's heart and to deliver pacing pulses to the first heart chamber, and wherein the LP2 is configured to be implanted in or on a second heart chamber of the patient's heart and to deliver pacing pulses to the second heart chamber, the system comprising: a controller configured to: obtain information about one or more of: an amplitude of the pacing pulses that the LP2 is configured to deliver to the second heart chamber, or a sensitivity of a sensing circuit of the LP1 that is configured to be used by the LP1 to detect intrinsic depolarizations of the first heart chamber; and determine a cross-talk protection duration based on at least some of the information; wherein the cross-talk protection duration is used by the LP1 after being determined to perform cross-talk protection for a duration of the cross-talk protection duration in response to the LP1 detecting a possible cross-talk that can be caused by the LP2 delivering one of the pacing pulses.

2. The system of claim 1, wherein, The controller is configured to: obtain information about an amplitude of the pacing pulses that the LP2 is configured to deliver to the second heart chamber; and determine the cross-talk protection duration based on the amplitude of the pacing pulses such that there is a positive correlation between the amplitude of the pacing pulses and the cross-talk protection duration.

3. The system of claim 2, wherein, The controller is configured to: obtain information about an amplitude of the pacing pulses that the LP2 is configured to deliver to the second heart chamber by obtaining information about at least one of a pulse amplitude or a pulse width of the pacing pulses that the LP2 is configured to deliver to the second heart chamber.

4. The system of any one of claims 1 to 3, wherein, The controller is configured to obtain information about a sensitivity of the sensing circuit of the LP1, and wherein: the sensitivity of the sensing circuit of the LP1 is specified by a sensing detection threshold of the sensing circuit of the LP1 that is configured to be used by the LP1 to detect intrinsic depolarizations of the first heart chamber, and the controller is configured to determine the cross-talk protection duration based on the sensing detection threshold of the sensing circuit of the LP1 such that there is a negative correlation between the sensing detection threshold of the sensing circuit of the LP1 and the cross-talk protection duration; or the sensitivity of the sensing circuit of the LP1 is specified by a gain of the sensing circuit of the LP1 that is configured to be used by the LP1 to 5. The system of any one of claims 1 to 4, wherein, detect intrinsic depolarizations of the first heart chamber, and the controller is configured to determine the cross- talk protection duration based on the gain of the sensing circuit of the LP1 such that there is a positive correlation between the gain of the sensing circuit of the LP1 and the cross-talk protection duration. The controller is configured to: obtain information about an amplitude that the LP2 is configured to deliver to the pacing pulses to the second heart chamber, and obtain information about a sensitivity of a sensing circuit of the LP1 that is configured to be used by the LP1 for detecting intrinsic depolarizations of the first heart chamber; and 6. The system of any one of claims 1 to 5, wherein, determine the cross-talk protection duration based on the amplitude of the pacing pulse and the sensitivity of the sensing circuit of the LP1. The controller is configured to: determined based on a scaling factor related to at least one of a distance between the LP1 and the LP2 or an angle of the LP1 and the LP2 relative to each other.

7. The system of any one of claims 1 to 6, wherein, The system comprises a portion of the LP1 including the controller, and wherein the controller of the LP1 is configured to: monitor for and detect possible cross-talk possibly caused by the LP2 delivering one of the pacing pulses; and initiate performance of cross-talk protection for the cross-talk protection duration in response to detecting possible cross-talk possibly caused by the LP2 delivering one of the pacing pulses.

8. The system of claim 7, wherein, The controller of the LP1 is configured to: dynamically adjust a sensitivity of a sensing circuit of the LP1; and update the cross-talk protection duration in response to the sensitivity of the sensing circuit of the LP1 being adjusted; wherein the sensitivity of the sensing circuit of the LP1 is specified by a sensing detection threshold of the sensing circuit of the LP1 configured to be used by the LP1 to detect intrinsic depolarizations of the first cardiac chamber, and the controller of the LP1 is configured to determine the cross-talk protection duration based on the sensing detection threshold of the sensing circuit of the LP1 such that there is a negative correlation between the sensing detection threshold of the sensing circuit of the LP1 and the cross-talk protection duration; or the sensitivity of the sensing circuit of the LP1 is specified by a gain of the sensing circuit of the LP1 configured to be used by the LP1 to detect intrinsic depolarizations of the first cardiac chamber, and the controller of the LP1 is configured to determine the cross-talk protection duration based on the gain of the sensing circuit of the LP1 such that there is a positive correlation between the gain of the sensing circuit of the LP1 and the cross-talk protection duration.

9. The system of any one of claims 7 or 8, wherein: the controller of the LP2 is configured to dynamically adjust an amplitude of a pacing pulse that the LP2 is configured to deliver to the second cardiac chamber, and to inform the controller of the LP1 of the adjustment made to the amplitude of the pacing pulse; and the controller of the LP1 is configured to determine the cross-talk protection duration based on the amplitude of the pacing pulse that the LP2 is configured to deliver to the second cardiac chamber such that there is a positive correlation between the amplitude of the pacing pulse and the cross-talk protection duration, and such that the controller of the LP1 updates the cross-talk protection duration in response to the controller of the LP1 being informed of the adjustment made to the amplitude of the pacing pulse.

10. The system of any one of claims 1 to 9, wherein, The system comprises a portion of the LP1 including the controller, and wherein the controller of LP1 is configured to provide cross-talk protection for the cross-talk protection duration by causing at least one of: blanking the sensing circuit of the LP1 for the cross-talk protection duration; ignoring any possible intrinsic depolarizations detected using the sensing circuit of the LP1 during the cross-talk protection duration; disabling the sensing circuit of the LP1 for the cross-talk protection duration; ignoring any interrupts generated in response to the sensing circuit for detecting possible intrinsic depolarizations during the cross-talk protection duration; or ignoring any possible intrinsic depolarizations detected using the sensing circuit of the LP1 during the duration of the cross-talk protection. disable generation of an interrupt that can be generated in response to the sensing circuit detecting intrinsic depolarization during the crosstalk protection duration.

11. The system of any one of claims 1 to 10, wherein, The system includes a portion of the LP1 that includes the controller, and wherein the controller of the LP1 is configured to: determine whether the detected possible crosstalk is part of a valid message sent by another device; and terminate the crosstalk protection for the remainder of the crosstalk protection duration in response to determining that the detected possible crosstalk is part of the valid message sent by another device.

12. The system of any one of claims 1 to 6, wherein, The system includes a non-implanted programmer that includes the controller and is configured to communicate with the LP1 and the LP2, and wherein the non-implanted programmer is configured to program the crosstalk protection duration into a memory or one or more registers of the LP1 such that the crosstalk protection duration is available to the LP1 when the LP1 detects possible crosstalk likely caused by the LP2 delivering one of the pacing pulses.

13. A leadless pacemaker configured to be implanted in or on a first heart chamber of a patient’s heart and configured to communicate with another leadless pacemaker configured to be implanted in or on a second heart chamber of the patient’s heart and to deliver pacing pulses to the second heart chamber, the leadless pacemaker comprising: a pulse generator configured to deliver pacing pulses to the first heart chamber; a sensing circuit configured to detect intrinsic depolarizations of the first heart chamber; and a controller configured to: obtain information about one or more of: an amplitude of the pacing pulses that the other leadless pacemaker is configured to deliver to the second heart chamber, or a sensitivity of the sensing circuit; determine a crosstalk protection duration based on at least some of the information; monitor for possible crosstalk likely caused by the other leadless pacemaker delivering one of the pacing pulses; and perform crosstalk protection for the crosstalk protection duration in response to detecting the possible crosstalk likely caused by the other leadless pacemaker delivering one of the pacing pulses.

14. The leadless pacemaker of claim 13, wherein, the controller is configured to: obtain information about an amplitude of the pacing pulses that the other leadless pacemaker is configured to deliver to the second chamber, and based thereon, determine the crosstalk protection duration such that there is a positive correlation between the amplitude of the pacing pulses and the crosstalk protection duration.

15. The leadless pacemaker of any one of claims 13 or 14, wherein, the controller is configured to: obtain information about a sensing detection threshold of the sensing circuit, and determine the crosstalk protection duration based on the sensing detection threshold of the sensing circuit such that there is a negative correlation between the sensing detection threshold of the sensing circuit and the crosstalk protection duration; or Information is obtained regarding a gain of the sense circuit, and the crosstalk protection duration is determined based on the gain of the sense circuit, such that there is a positive correlation between the gain of the sense circuit and the crosstalk protection duration.

16. The leadless pacemaker of any of claims 13 to 15, wherein, The controller is configured to: obtain information regarding an amplitude of a pacing pulse that the other leadless pacemaker is configured to deliver to the second heart chamber; obtain information regarding a sensitivity of the sense circuit; and determine the crosstalk protection duration based on the amplitude of the pacing pulse and the sensitivity of the sense circuit.

17. The leadless pacemaker of any of claims 13 to 16, wherein, The controller is configured to: determine the crosstalk protection duration based on at least one of a distance between the leadless pacemaker and the other leadless pacemaker or an angle of the leadless pacemaker and the other leadless pacemaker relative to each other.

18. The leadless pacemaker of any of claims 13 to 17, wherein, The controller is configured to: dynamically adjust a sensitivity of the sense circuit; and determine the crosstalk protection duration based on the sensitivity of the sense circuit, such that the crosstalk protection duration is updated as the sensitivity of the sense circuit is adjusted.

19. The leadless pacemaker of any of claims 13 to 18, wherein, The controller is configured to: determine the crosstalk protection duration based on the amplitude of the pacing pulse that the other leadless pacemaker is configured to deliver to the second heart chamber, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration, wherein the crosstalk protection duration is updated in response to being notified of the adjustment to the amplitude of the pacing pulse that the other leadless pacemaker is configured to deliver to the second heart chamber.

20. The leadless pacemaker of any of claims 13 to 19, wherein, The controller is configured to provide crosstalk protection for the crosstalk protection duration by causing at least one of: blanking the sense circuit for the crosstalk protection duration; ignoring any possible intrinsic depolarizations detected using the sense circuit during the crosstalk protection duration; disabling the sense circuit for the crosstalk protection duration; ignoring any interrupts generated in response to the sense circuit for detecting possible intrinsic depolarizations during the crosstalk protection duration; or disabling generation of interrupts that can be generated in response to the sense circuit detecting intrinsic depolarizations during the crosstalk protection duration.

21. The leadless pacemaker of any of claims 13 to 20, wherein, The controller is configured to: determine whether the detected possible crosstalk is part of a valid message sent by another device; and terminate the crosstalk protection for a remaining time of the crosstalk protection duration in response to determining that the detected possible crosstalk is part of the valid message sent by another device.

22. A cross-talk protection method for a dual chamber leadless pacemaker (LP) system comprising a first leadless pacemaker (LP1) and a second leadless pacemaker (LP2), wherein, The LP1 is configured to be implanted in or on a first heart chamber of a patient's heart and to deliver pacing pulses to the first heart chamber, and the LP2 is configured to be implanted in or on a second heart chamber of the patient's heart and to deliver pacing pulses to the second heart chamber, the method comprising: obtaining information regarding one or more of: The LP2 is configured to determine the amplitude of the pacing pulse delivered to the second cardiac chamber, or The sensitivity of the sensing circuit of the LP1 is configured to be used by the LP1 to detect the inherent depolarization of the first cardiac chamber. The duration of crosstalk protection is determined based on at least some of the information; LP1 monitors and detects potential crosstalk that may be caused by a pacing pulse delivered by LP2; and In response to the detection of potential crosstalk that may be caused by LP2 in one of the delivered pacing pulses, LP1 initiates crosstalk protection for the duration of the crosstalk protection.

23. The method according to claim 22, wherein: The information obtained includes information about the amplitude of the pacing pulse that LP2 is configured to deliver to the second ventricle of the heart; and The duration of crosstalk protection is determined based on the amplitude of the pacing pulse, such that there is a positive correlation between the amplitude of the pacing pulse and the duration of crosstalk protection.

24. The method of claim 23, wherein, Obtaining information about the amplitude of the pacing pulse that the LP2 is configured to deliver to the second heart chamber includes obtaining information about at least one of the pulse amplitude or pulse width of the pacing pulse that the LP2 is configured to deliver to the second heart chamber.

25. The method according to any one of claims 22 to 24, wherein obtaining the information includes obtaining information about the sensitivity of the sensing circuit of the LP1, and wherein: The sensitivity of the sensing circuit of LP1 is specified by the sensing detection threshold of the sensing circuit of LP1, which is configured to be used by LP1 to detect the inherent depolarization of the first heart chamber and to determine the crosstalk protection duration based on the sensing detection threshold of the sensing circuit, such that there is a negative correlation between the sensing detection threshold of the sensing circuit and the crosstalk protection duration. or The sensitivity of the sensing circuit of LP1 is specified by the gain of the sensing circuit of LP1, which is configured by LP1 to detect the inherent depolarization of the first cardiac chamber, and the crosstalk protection duration is determined based on the gain of the sensing circuit such that there is a positive correlation between the gain of the sensing circuit and the crosstalk protection duration.

26. The method according to any one of claims 22 to 25, wherein: The information obtained includes information about the amplitude of the pacing pulse that LP2 is configured to deliver to the second heart chamber, and information about the sensitivity of the sensing circuitry of LP1, which is configured to be used by LP1 to detect the inherent depolarization of the first heart chamber. and The duration of crosstalk protection is determined based on the amplitude of the pacing pulse and the sensitivity of the sensing circuit.

27. The method according to any one of claims 22 to 26, wherein: The duration of crosstalk protection is also determined based on at least one of the relevant scaling factors, namely the distance between LP1 and LP2 or the angles of LP1 and LP2 relative to each other.

28. The method of any one of claims 22-27, wherein, The duration of the crosstalk protection is determined by the controller of LP1.

29. The method according to claim 28, wherein: The controller of the LP1 is configured to dynamically adjust the sensitivity of the sensing circuit of the LP1; and The crosstalk protection duration is determined based on the sensitivity of the LP1 sensing circuit, so that when the LP1 controller adjusts the sensitivity of the LP1 sensing circuit, the LP1 controller updates the crosstalk protection duration.

30. The method according to any one of claims 28 or 29, wherein: The controller of LP2 is configured to dynamically adjust the amplitude of the pacing pulse that LP2 is configured to deliver to the second cardiac chamber, and to notify the controller of LP1 of the adjustment to the amplitude of the pacing pulse. and The crosstalk protection duration is determined based on the amplitude of the pacing pulse that LP2 is configured to deliver to the second cardiac chamber, such that there is a positive correlation between the amplitude of the pacing pulse and the crosstalk protection duration. and The controller of LP1 updates the crosstalk protection duration in response to the notification from LP2 to the controller of LP1 regarding the adjustment of the pacing pulse amplitude.

31. The method according to any one of claims 22 to 27, wherein: The acquisition of the information and the determination of the crosstalk protection duration are performed by a non-implantable programmer; and The method further includes a non-implantable programmer programming the crosstalk protection duration into the memory or one or more registers of LP1, such that the crosstalk protection duration is available to LP1 when LP1 detects potential crosstalk that may be caused by a pacing pulse delivered by LP2.

32. The method of any one of claims 22-31, wherein, Providing crosstalk protection during the crosstalk protection duration includes at least one of the following: The sensing circuit of LP1 is blanked during the crosstalk protection duration; Ignore any possible inherent depolarization detected by the sensing circuit using the LP1 during the crosstalk protection duration; The sensing circuit of LP1 is disabled during the crosstalk protection duration; Ignore any interruptions generated by the sensing circuit in response to detecting possible inherent depolarization during the crosstalk protection duration; or Disabling interrupt generation, which may be generated in response to the sensing circuit detecting possible inherent depolarization during the crosstalk protection duration.

33. The method according to any one of claims 22 to 32, further comprising: If it is determined that the detected potential crosstalk is part of a valid message sent by another device, and in response thereto, the crosstalk protection is terminated for the remaining time of the crosstalk protection duration.

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