Dual-lumen leadless pacemaker system for monitoring and adjusting AV synchronization and method of use thereof

Abstract

A system includes, or is used with, an atrial leadless pacemaker (aLP) and a ventricular leadless pacemaker (vLP), the atrial leadless pacemaker (aLP) and the ventricular leadless pacemaker (vLP) being configured to communicate with each other, and collectively providing a DDD operation when an a2v message sent by the aLP is successfully received by the vLP and a v2a message sent by the vLP is successfully received by the aLP during a cardiac cycle. The aLP and the vLP are further configured to collectively provide a VDD operation, a DDI operation, or a VDI operation when an a2v message sent by the aLP is not successfully received by the vLP and / or a v2a message sent by the vLP is not successfully received by the aLP at least some. One or more processors of the system are configured to determine AV synchronization metrics over a time period and provide one or more responses based thereon. Related methods are also described.

Description

[0001] Priority declaration

[0002] This application claims priority to U.S. Non-Provisional Patent Application No. 18 / 805,834 filed on August 15, 2024 and U.S. Provisional Patent Application No. 63 / 584,732 filed on September 22, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] Embodiments described herein generally relate to methods and systems for monitoring and potentially adjusting (eg, improving) atrial-ventricular (AV) synchronization provided by a dual-chamber leadless pacemaker (LP) system. Background Art

[0004] In certain dual-chamber cardiac pacing systems, multiple leadless pacemakers communicate wirelessly with each other to reliably and safely coordinate pacing and / or sensing operations. Such a system may include, for example, a ventricular leadless pacemaker (vLP) implanted in or on the right ventricle (RV) and an atrial leadless pacemaker (aLP) implanted in or on the right atrium (RA), wherein the vLP and the aLP communicate wirelessly with each other to coordinate pacing and / or sensing operations. Such wireless communication between two IMDs (e.g., two LPs) is generally referred to as implant-to-implant (i2i) communication. When using a pair of LPs to perform pacing and / or sensing operations in the RA and RV, one of the challenges is the reliance on bidirectional i2i communication to maintain proper atrial-ventricular (AV) synchronization. However, for a variety of different reasons, there may be periods of time when the bidirectional i2i communication fails due to noise and / or the relative orientation of the LPs (but not limited to). Summary of the invention

[0005] Certain embodiments of the present technology relate to a method for use with a dual-chamber leadless pacemaker (LP) system, the dual-chamber leadless pacemaker (LP) system comprising an atrial leadless pacemaker (aLP) and a ventricular leadless pacemaker (vLP) configured to communicate with each other, wherein the aLP and the vLP are configured to jointly provide a DDD operation when an atrial-to-ventricular (a2v) message sent by the aLP is successfully received by the vLP and a ventricular-to-atrial (v2a) message sent by the vLP is successfully received by the aLP during a cardiac cycle. The aLP and the vLP are configured to jointly provide at least one of a VDD operation, a DDI operation, or a VDI operation during another cardiac cycle when at least one of an a2v message sent by the aLP is not successfully received and / or a v2a message sent by the vLP is not successfully received occurs. The method includes obtaining a2v throughput, v2a throughput, and event sequence information during a time period when the aLP and the vLP are configured to jointly provide the DDD operation. The method further includes determining an estimated DDD metric, an estimated VDD metric, an estimated DDI metric, and an estimated VDI metric for the time period based on the a2v throughput and the v2a throughput. The method further includes determining an atrial-ventricular (AV) synchronization metric for the time period based on the estimated DDD metric, the estimated VDD metric, the estimated DDI metric, the estimated VDI metric, and the event sequence information, wherein the AV synchronization metric specifies an estimate of how often AV synchronization is achieved during the time period.

[0006] In accordance with certain embodiments, the method also includes adjusting, based on the AV synchronization metric, at least one parameter used by the aLP to send additional a2v messages to the vLP, at least one parameter used by the vLP to receive additional a2v messages from the aLP, at least one parameter used by the vLP to send additional v2a messages to the aLP, and / or at least one parameter used by the aLP to receive additional v2a messages from the vLP.

[0007] According to some embodiments, the method additionally or alternatively includes adjusting an implantation position of at least one of the aLP or the vLP based on the AV synchronization metric.

[0008] According to some embodiments, the method additionally or alternatively includes displaying an AV synchronization metric.

[0009] According to some embodiments, the aLP is configured to send an a2v message to the vLP. The vLP is configured to attempt to receive an a2v message from the aLP. The vLP is configured to send a v2a message to the aLP. The aLP is configured to attempt to receive a v2a message from the vLP.

[0010] According to certain embodiments, the a2v throughput specifies the frequency with which a2v messages sent by the aLP are successfully received by the vLP during a time period in which the aLP and the vLP are configured to jointly provide DDD operations. The v2a throughput specifies the frequency with which v2a messages sent by the vLP are successfully received by the aLP during the time period. The sequence of events information specifies the frequency with which each of a plurality of different combinations of pacing and sensing occurs during the time period.

[0011] According to certain embodiments, the estimated DDD metric specifies an estimate of how often the aLP and vLP jointly provide DDD operations during a time period in which the aLP and vLP are configured to jointly provide DDD operations. The estimated VDD metric specifies an estimate of how often the aLP and vLP jointly provide VDD operations during the time period. The estimated DDI metric specifies an estimate of how often the aLP and vLP jointly provide DDI operations during the time period. The estimated VDI metric specifies an estimate of how often the aLP and vLP jointly provide VDI operations during the time period.

[0012] According to certain embodiments, the event sequence information includes AP-VP information, AP-VS information, AS-VP information, and AS-VS information. The AP-VP information specifies the frequency at which aLP provides atrial pacing (AP) and vLP provides ventricular pacing (VP) for the same cardiac cycle during a time period when aLP and vLP are configured to jointly provide DDD operation. The AP-VS information specifies the frequency at which aLP provides AP and vLP provides ventricular sensing (VS) for the same cardiac cycle during the time period, and the AS-VP information specifies the frequency at which aLP provides atrial sensing (AS) and vLP provides VP for the same cardiac cycle during the time period. The AS-VS information specifies the frequency at which aLP provides AS and vLP provides VS for the same cardiac cycle during the time period.

[0013] According to certain embodiments, determining an estimated DDD metric, an estimated VDD metric, an estimated DDI metric, and an estimated VDI metric based on the a2v throughput and the v2a throughput includes: determining that the estimated DDD metric is equal to the minimum of the a2v throughput and the v2a throughput; determining that the estimated VDD metric is equal to the a2v throughput minus the estimated DDD metric; determining that the estimated DDI metric is equal to the v2a throughput minus the estimated DDD metric; and determining that the estimated VDI metric is equal to 100% minus the sum of the estimated DDD metric, the estimated VDD metric, and the estimated DDI metric.

[0014] According to certain embodiments, determining an estimated DDD metric, an estimated VDD metric, an estimated DDI metric, and an estimated VDI metric based on the a2v throughput and the v2a throughput includes: determining that the estimated DDD metric is equal to the maximum of: zero; and 100% minus the sum of the percentage of a2v messages that the vLP did not successfully receive and the percentage of v2a messages that the aLP did not successfully receive; determining that the estimated VDD metric is equal to the a2v throughput minus the estimated DDD metric; determining that the estimated DDI metric is equal to the v2a throughput minus the estimated DDD metric; and determining that the estimated VDI metric is equal to 100% minus the sum of the estimated DDD metric, the estimated VDD metric, and the estimated DDI metric.

[0015] According to certain embodiments, the method is performed by a non-implanted system that receives a2v throughput and v2a throughput from at least one of aLP or vLP, or receives a2v throughput and v2a throughput from another system that has received a2v throughput and v2a throughput from at least one of aLP or vLP.

[0016] According to certain embodiments, the method is performed by at least one of an aLP or a vLP.

[0017] Certain embodiments of the present technology relate to a system comprising or for use with an atrial leadless pacemaker (aLP) and a ventricular leadless pacemaker (vLP) configured to communicate with each other, wherein the aLP and the vLP are configured to jointly provide a DDD operation when an atrial-to-ventricular (a2v) message sent by the aLP is successfully received by the vLP and a ventricular-to-atrial (v2a) message sent by the vLP is successfully received by the aLP during a cardiac cycle. The aLP and the vLP are configured to jointly provide at least one of a VDD operation, a DDI operation, or a VDI operation when at least one of an a2v message sent by the aLP and / or a v2a message sent by the vLP is unsuccessfully received by the vLP during another cardiac cycle. The system includes one or more processors configured to obtain a2v throughput, v2a throughput, and event sequence information during a time period in which an aLP and a vLP are configured to jointly provide a DDD operation. The one or more processors of the system are further configured to determine an estimated DDD metric, an estimated VDD metric, an estimated DDI metric, and an estimated VDI metric during the time period based on the a2v throughput and the v2a throughput. The one or more processors of the system are further configured to determine an atrial-ventricular (AV) synchronization metric during the time period based on the estimated DDD metric, the estimated VDD metric, the estimated DDI metric, the estimated VDI metric, and the event sequence information, wherein the AV synchronization metric specifies an estimate of the frequency at which AV synchronization is achieved during the time period.

[0018] According to certain embodiments, the system includes an aLP and a vLP, each of which includes a corresponding processor and corresponding at least two electrodes, wherein the aLP is configured to be implanted in or on an atrial heart chamber, and the vLP is configured to be implanted in or on a ventricular heart chamber. In addition, the aLP is configured to send an a2v message to the vLP, and the vLP is configured to attempt to receive an a2v message from the aLP. The vLP is configured to send a v2a message to the aLP, and the aLP is configured to attempt to receive a v2a message from the vLP.

[0019] According to some embodiments, the processor of the vLP or the processor of the aLP includes at least one of the one or more processors configured to determine an AV synchronization metric. In addition, the processor of the vLP or at least one of the processors of the aLP is further configured to adjust one or more parameters of at least one of the aLP or the vLP based on the AV synchronization metric.

[0020] According to some embodiments, the system includes a non-implanted subsystem (e.g., a device) that includes at least one of the one or more processors, the at least one processor configured to determine an AV synchronization metric during the time period. The at least one processor of the non-implanted subsystem (e.g., a device) is configured to adjust one or more parameters of at least one of the aLP or the vLP based on the AV synchronization metric.

[0021] In accordance with certain embodiments, one or more processors configured to determine the AV synchronization metric within the time period are also configured to adjust, based on the AV synchronization metric, at least one parameter used by the aLP for sending additional a2v messages to the vLP, at least one parameter used by the vLP for receiving additional a2v messages from the aLP, at least one parameter used by the vLP for sending additional v2a messages to the aLP, and / or at least one parameter used by the aLP for receiving additional v2a messages from the vLP.

[0022] According to some embodiments, the one or more processors configured to determine the AV synchronization metric for the time period are further configured to cause the AV synchronization metric to be displayed.

[0023] According to certain embodiments, the one or more processors configured to determine the AV synchronization metric within the time period are further configured to provide a notification that the implantation position of at least one of the aLP or the vLP should be modified.

[0024] According to certain embodiments, the estimated DDD metric specifies an estimate of how often the aLP and vLP jointly provide DDD operations during a time period when the aLP and vLP are configured to jointly provide DDD operations. The estimated VDD metric specifies an estimate of how often the aLP and vLP jointly provide VDD operations during the time period. The estimated DDI metric specifies an estimate of how often the aLP and vLP jointly provide DDI operations during the time period. The estimated VDI metric specifies an estimate of how well the aLP and vLP jointly provide VDI operations during the time period.

[0025] According to certain embodiments, the event sequence information includes AP-VP information, AP-VS information, AS-VP information, and AS-VS information. The AP-VP information specifies the frequency at which aLP provides atrial pacing (AP) and vLP provides ventricular pacing (VP) for the same cardiac cycle during a time period when the aLP and vLP are configured to jointly provide DDD operation. The AP-VS information specifies the frequency at which aLP provides AP and vLP provides ventricular sensing (VS) for the same cardiac cycle during the time period. The AS-VP information specifies the frequency at which aLP provides atrial sensing (AS) and vLP provides VP for the same cardiac cycle during the time period. The AS-VS information specifies the frequency at which aLP provides AS and vLP provides VS for the same cardiac cycle during the time period.

[0026] Certain embodiments of the present technology relate to a method for use with a dual-chamber leadless pacemaker (LP) system, the dual-chamber leadless pacemaker (LP) system comprising an atrial leadless pacemaker (aLP) and a ventricular leadless pacemaker (vLP), the atrial leadless pacemaker (aLP) and the ventricular leadless pacemaker (vLP) being configured to communicate with each other and to jointly provide DDD operation when an atrial-to-ventricular (a2v) message sent by the aLP is successfully received by the vLP and a ventricular-to-atrial (v2a) message sent by the vLP is successfully received by the aLP during a cardiac cycle, and wherein the aLP and the vLP are configured to jointly provide at least one of VDD, DDI, or VDI operation when at least one of an a2v message sent by the aLP is not successfully received by the vLP and / or a v2a message sent by the vLP is not successfully received by the aLP during another cardiac cycle. The method includes: obtaining a2v throughput, v2a throughput, and event sequence information during a time period when an aLP and a vLP are configured to jointly provide DDD operations; determining an estimate of the frequency at which the aLP and the vLP jointly provide each of DDD, VDD, DDI, and VVI operations during the time period based on the a2v throughput and the v2a throughput; determining an atrial-ventricular (AV) synchronization metric during the time period based on the estimate; and adjusting at least one parameter used by the aLP to communicate with the vLP and / or at least one parameter used by the vLP to communicate with the aLP based on the AV synchronization metric. According to some embodiments, the method is performed by a non-implanted system that receives the a2v throughput and the v2a throughput from at least one of the aLP or the vLP, or receives the a2v throughput and the v2a throughput from another system that has received the a2v throughput and the v2a throughput from at least one of the aLP or the vLP. According to other embodiments, the method is performed by at least one of the aLP or the vLP.

[0027] Certain embodiments of the present technology relate to a system comprising or for use with an atrial leadless pacemaker (aLP) and a ventricular leadless pacemaker (vLP), the atrial leadless pacemaker (aLP) and the ventricular leadless pacemaker (vLP) being configured to communicate with each other and to jointly provide a DDD operation when an atrial-to-ventricular (a2v) message sent by the aLP is successfully received by the vLP and a ventricular-to-atrial (v2a) message sent by the vLP is successfully received by the aLP during a cardiac cycle, and wherein the a2v message sent by the aLP is not successfully received by the vLP and / or a v2a message sent by the vLP is not successfully received by the aLP during another cardiac cycle. When at least one of the successful receptions occurs, the system includes one or more processors configured to: obtain a2v throughput, v2a throughput, and event sequence information during a time period when the aLP and the vLP are configured to jointly provide DDD operations; determine an estimate of the frequency at which the aLP and the vLP jointly provide each of the DDD, VDD, DDI, and VVI operations during the time period based on the a2v throughput and the v2a throughput; determine an atrial-ventricular (AV) synchronization metric during the time period based on the estimate; and adjust at least one parameter used by the aLP to communicate with the vLP and / or at least one parameter used by the vLP to communicate with the aLP based on the AV synchronization metric. According to some embodiments, the system includes an aLP and a vLP, each of which includes a corresponding processor and a corresponding at least two electrodes; at least one of the processors of the vLP or the processors of the aLP includes at least one of the one or more processors configured to determine the AV synchronization metric; and at least one of the processors of the vLP or the processors of the aLP is configured to adjust at least one parameter used by the aLP to communicate with the vLP and / or at least one parameter used by the vLP to communicate with the aLP. According to other embodiments, the system includes a non-implanted subsystem, the non-implanted subsystem including at least one of the one or more processors, the at least one processor configured to determine the AV synchronization metric within the time period, and adjust at least one parameter used by the aLP to communicate with the vLP and / or at least one parameter used by the vLP to communicate with the aLP based on the AV synchronization metric.

[0028] This summary 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 described in detail in conjunction with the accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Embodiments of the present technology, both as to structure and method of operation, may be best understood by reference to the following description and drawings, wherein like reference numerals represent like elements throughout the several views:

[0030] Figure 1A A system formed to be implanted in a heart according to certain embodiments described herein is shown.

[0031] Figure 1B is a block diagram of a LP according to some embodiments herein.

[0032] Figure 2 An LP according to some embodiments herein is shown.

[0033] Figure 3 is a timing diagram illustrating one embodiment of conducted i2i communication for pacing events.

[0034] Figure 4 is a timing diagram illustrating one embodiment of conducted i2i communication for sensing events.

[0035] Figure 5 is a diagram for illustrating how the orientation of two different LPs can affect i2i communication, thereby affecting a2v throughput and / or v2a throughput.

[0036] Figures 6A-6C is a high-level flow chart outlining certain embodiments of the present technology for determining and using AV synchronization metrics.

[0037] Figure 7 is an example graph showing possible values ​​(and more specifically, percentages) for a2v throughput and v2a throughput achieved by a dual-chamber LP system.

[0038] Figure 8 is to show how to use Figure 7 Example graphs of determining the DDDmax duration metric and the corresponding VDI, DDI, and VDD duration metrics based on the a2v throughput and v2a throughput introduced in FIG.

[0039] Fig. 9 is to show how to use Figure 7 Example graphs of determining the DDDmin duration metric and the corresponding VDI, DDI, and VDD duration metrics based on the a2v throughput and v2a throughput introduced in FIG.

[0040] Fig.10 is corresponding to Figure 7 Schematic diagram of a2v throughput and v2a throughput introduced in and helps to visualize the time overlap options for successful a2v communication and successful v2a communication.

[0041] Fig.11 and Fig.12 is a graphical representation of an example distribution of event sequence information.

[0042] Fig.13 A block diagram is shown of one embodiment of an LP implanted in a patient as part of a dual lumen LP system according to some embodiments herein.

[0043] Fig.14 An example system is shown that may be used to determine, display, and otherwise use one or more AV synchronization metrics in accordance with embodiments of the present technology.

[0044] Fig.15 A system-level diagram indicating potential devices and networks utilizing the methods and systems herein is shown. DETAILED DESCRIPTION

[0045] A dual-chamber implantable leadless pacemaker (LP) system according to certain embodiments of the present technology includes an atrial LP (aLP) configured to be implanted in or on the right atrium (RA) of a patient's heart and a ventricular LP (vLP) configured to be implanted in or on the right ventricle (RV) of the patient's heart. In certain embodiments, the aLP and the vLP are configured to provide bidirectional implant-to-implant (i2i) communication with each other, thereby enabling them to jointly provide synchronized dual-chamber cardiac pacing. More specifically, the aLP is configured to send an atrial-to-ventricular (a2v) message to the vLP, and the vLP is configured to attempt to receive an a2v message from the aLP. The vLP is configured to send a ventricular-to-atrial (v2a) message to the aLP, and the aLP is configured to attempt to receive a v2a message from the vLP. Such an a2v message sent by the aLP and intended to be received by the vLP may be used to notify the vLP of an intrinsic atrial event sensed by the aLP or a paced atrial event caused (or to be caused) by the aLP. Such a v2a message sent by the vLP and intended to be received by the aLP may be used to notify the aLP of an intrinsic ventricular event sensed by the vLP or a paced ventricular event caused (or to be caused) by the vLP. Note that the terms right ventricle (RV) and right ventricular (RV) chamber are used interchangeably herein, and the acronym RV may represent right ventricular or right ventricle, depending on the context. Similarly, the terms right atrium (RA) and right atrial (RA) chamber are used interchangeably herein, and the acronym RA may represent right atrial or right atrium, depending on the context.

[0046] When referring to various types of operating schemes (also called modes) in this article, three letters are generally used to refer to the type of operation. In other words, a three-position pacemaker code is generally used, following the following nomenclature: the first position refers to the cardiac chamber being paced; the second position refers to the cardiac chamber being sensed; and the third position refers to the response to a sensed event. In the first and second positions, the letter O represents none, the letter A represents atrium, the letter V represents ventricle, and the letter D represents double (i.e., A and V). In the third position, the letter O represents none, the letter I represents inhibit, the letter T represents trigger (also called tracking), and the letter D represents double (i.e., T+I). Table 1 below summarizes this pacemaker nomenclature. Where R is included in the fourth position, this means that the pacing provided is rate responsive.

[0047]

[0048] As is known in the art, the DDD and DDD(R) modes of operation provide synchronized dual-chamber pacing. More specifically, DDD operation provides atrial and ventricular pacing, atrial and ventricular sensing, and the ability to inhibit or trigger pacing after a sensed event. DDD(R) operation is rate-responsive DDD operation, i.e., the pacing rate is adjusted based on the patient's activity level (e.g., as detected using a motion sensor and / or a temperature sensor). As used herein, the term DDD operation also encompasses DDD(R) operation.

[0049] Although neither aLP nor vLP can perform DDD operations alone, aLP and vLP can be configured to jointly provide DDD operations (including DDD(R) operations) when there is successful two-way i2i communication (i.e., when vLP successfully receives a2v messages from aLP and aLP successfully receives v2a messages from vLP).

[0050] However, due to various reasons, there may be periods of time when bidirectional i2i communication fails because the vLP fails to successfully receive one or more a2v messages from the aLP, and / or the aLP fails to successfully receive one or more v2a messages from the vLP. Such failures in i2i communication may occur, for example, due to noise and / or the relative orientation of the aLP and vLP, but are not limited thereto.

[0051] The dual chamber LP system may have safeguards in place to reduce asynchronous pacing in the event of loss of i2i communication in one or both directions, as outlined in Table 2 below.

[0052]

[0053] As can be understood from Table 2 above, in a dual-chamber LP system including an aLP and a vLP configured to jointly provide DDD operation, if a2v communication is lost (i.e., the vLP does not successfully receive one or more a2v messages sent by the aLP), the vLP stops tracking atrial activity and the dual-chamber LP system effectively provides DDI operation. If v2a communication is lost (i.e., one or more v2a messages sent by the vLP are not successfully received by the aLP), the aLP stops pacing and the dual-chamber LP system effectively provides VDD operation. If i2i communication is lost in both directions at the same time (i.e., the v2a message sent by the vLP is not successfully received by the aLP, and the a2v message sent by the aLP is not successfully received by the vLP), both mitigations are in effect and the dual-chamber LP system effectively provides VDI operation. These transmission reception protection measures are used to guarantee RV pacing while maintaining RA tracking and RA pacing as much as possible.

[0054] The vLP is configured to send an acknowledgment (ACK) message when the vLP successfully receives an a2v message from the aLP, and the aLP is configured to send an ACK message to the vLP when the aLP successfully receives a v2a message from the vLP. In this way, the aLP can track its a2v throughput, and the vLP can track its v2a throughput, both of which can be uploaded from one or both LPs to an external system (e.g., an external programmer, a patient monitor, or a patient link module) that communicates with one or both LPs. For example, the aLP can send a2v throughput information to an external system, and the vLP can send v2a throughput information to the external system alone. For another example, the aLP can send a2v throughput information to the vLP, and the vLP can send both v2a throughput information and a2v throughput information to the external system. For the purposes of this discussion, when the aLP successfully detects and decodes a v2a message, the aLP is considered to have successfully received a v2a message, and when the vLP successfully detects and decodes a v2a message, the vLP is considered to have successfully received an a2v message.

[0055] Once the a2v throughput and v2a throughput information is provided to an external system (e.g., an external programmer or a patient care network (PCN)), the throughput information can be presented to a user of the external system (e.g., a clinician and / or physician) (e.g., via a display monitor). For example, the a2v throughput information can specify a percentage of a2v messages sent by the aLP that were successfully received by the vLP, and the v2a throughput information can specify a percentage of v2a messages sent by the vLP that were successfully received by the aLP. However, such a2v and v2a throughput information, by itself, does not provide the user with an indication of the percentage of cardiac cycles in which DDD operation was effectively achieved, and does not provide the user with an indication of the percentage of cardiac cycles in which AV synchronization was achieved. Certain embodiments of the present technology described herein calculate an estimate of the frequency with which a dual-chamber LP system (including an aLP and a vLP) provides DDD operation and in one or more protected types of pacing. In addition, certain embodiments of the present technology described herein calculate an estimate of the frequency with which a dual-chamber LP system provides AV synchronization. Furthermore, according to certain embodiments of the present technology described herein, at least one parameter used by the aLP to send additional a2v messages to the vLP, at least one parameter used by the vLP to receive additional a2v messages from the aLP, at least one parameter used by the vLP to send additional v2a messages to the aLP, and / or at least one parameter used by the aLP to receive additional v2a messages from the vLP is adjusted based on the estimated AV synchronization. Additional details of such embodiments are provided herein. However, before providing additional details of specific embodiments of the present technology described above, reference will first be made to Figure 1A , Figure 1B and Figure 2 Exemplary systems are described in which or with which embodiments of the present technology may be used.

[0056] Figure 1A A system 100 is shown that is formed to be implanted in a heart 101 according to certain embodiments herein. The system 100 includes two LPs 102 and 104 located in different chambers of the heart. LP 102 is located in the right atrium (RA), while LP 104 is located in the right ventricle (RV). Therefore, LP 102 may also be more specifically referred to as aLP 102, and LP 104 may also be more specifically referred to as vLP 104. RA is also referred to as the right atrial chamber, and RV is also referred to as the right ventricular chamber. Such chambers of the patient's heart may also be referred to as cardiac chambers herein. LP 102 and 104 communicate with each other to notify each other of various local physiological activities, such as local intrinsic events, local pacing events, etc. LP 102 and 104 can be constructed in a similar manner, but operate differently based on which chamber LP 102 or 104 is located.

[0057] In some embodiments, LPs 102 and 104 communicate with each other and with an optional ICD 106 and with an external system (e.g., a programmer) 109 through wireless transceivers, communication coils, and antennas and / or through conducted i2i communication over the same electrodes as used for sensing and / or delivering pacing therapy. When conducting i2i communication is maintained over the same electrodes as used for pacing, the system 100 can omit an antenna or telemetry coil in one or more of the LPs 102 and 104. For much of the following discussion, it is assumed that LPs 102 and 104 communicate with each other and with other devices using conducted communication, thereby eliminating the need for LPs 102 and 104 to include antennas or telemetry coils. However, it should be noted that many of the embodiments described herein can also be used in situations where LPs 102 and 104 utilize antennas and / or telemetry coils to perform i2i communication. In addition, it should also be noted that conducted communication can also be equivalently referred to as conductive communication.

[0058] In some embodiments, one or more LPs 102 and 104 may be co-implanted with an ICD 106, however this need not be the case. Each LP 102, 104 uses two or more electrodes located within, on, or within a few centimeters of the housing of the LP for pacing and sensing at the cardiac chambers, for bidirectional communication with each other, with an external system (e.g., a programmer) 109, and with the ICD 106.

[0059] refer to Figure 1B , a block diagram illustrating exemplary electronics within LPs 102 and 104. LPs 102, 104 include first receivers 120 and second receivers 122 that together define separate first and second communication channels 105, 107 between LPs 102 and 104 ( Figure 1A ). Although a first receiver 120 and a second receiver 122 are depicted, in other embodiments, the LP 102, 104 may include only the first receiver 120, or may include additional receivers in addition to the first receiver 120 and the second receiver 122. As will be described in more detail below, the pulse generator 116 may be used as a transmitter to send i2i communication signals using the electrodes 108. Communicating using the electrodes 108 enables one or more LPs 102 and 104 to perform antenna-less and telemetry coil-less communication. The same pulse generator 116 may be used to generate both pacing pulses and conducted communication pulses, in which case the LP may include only a single pulse generator 116. Alternatively, the LP may include more than one pulse generator, for example, where one pulse generator may be used to generate pacing pulses and another pulse generator may be used to generate conducted communication pulses.

[0060] According to certain embodiments, when one of the LPs 102 and 104 senses an intrinsic event or delivers a pacing event, the corresponding LP 102, 104 sends an implant event message to the other LP 102, 104. For example, when the aLP 102 senses / paces an atrial event, the aLP 102 sends an implant event message including an event marker indicating the nature of the event (e.g., intrinsic / sensed atrial event, paced atrial event). When the vLP 104 senses / paces a ventricular event, the vLP 104 sends an implant event message including an event marker indicating the nature of the event (e.g., intrinsic / sensed ventricular event, paced ventricular event). In certain embodiments, the LP 102, 104 sends the implant event message to the other LP 102, 104 before the actual pacing pulse so that the remote LP can blank its sensing input in anticipation of the remote pacing pulse (to prevent inappropriate crosstalk sensing).

[0061] Still reference Figure 1B , each LP 102, 104 is shown to include a controller 112 and a pulse generator 116. The controller 112 may include, for example, a microprocessor (or equivalent control circuitry), RAM and / or ROM memory, logic and timing circuitry, state machine circuitry, and I / O circuitry, but is not limited thereto. The controller 112 may also include, for example, timing control circuitry for controlling the timing of stimulation pulses (e.g., pacing rate, atrial-ventricular (AV) delay, atrial interconductio delay, or ventricular interconduction delay, etc.). Such timing control circuitry may also be used for timing of refractory periods, blanking intervals, noise detection windows, induced response windows, alarm intervals, marker channel timing, etc. The controller 112 may also include other dedicated circuitry and / or firmware / software components that assist in monitoring various conditions of the patient's heart and managing pacing therapy. The controller 112 and the pulse generator 116 may be configured to send the event message via the electrodes 108 in a manner that does not inadvertently capture the heart in the chamber in which the LP 102, 104 is located (e.g., when the associated chamber is in a refractory state). Additionally, the LP 102, 104 that receives the event message may enter an "event refractory" state (or event blanked state) after receiving the event message. The event refractory / blanked state may be set to extend for a determined period of time after receiving the event message in order to avoid the receiving LP 102, 104 from inadvertently sensing another signal as an event message that may otherwise result in a re-triggering. For example, the receiving LP 102, 104 may detect a measurement pulse from another LP 102, 104 or the programmer 109.

[0062] According to certain embodiments herein, programmer 109 can utilize the same communication scheme to communicate with LP 102, 104 over a programmer-to-LP channel. External programmer 109 can listen to event messages sent between LP 102, 104 and synchronize programmer to implant communications such that programmer 109 does not send communication signals 113 until after the implant-to-implant messaging sequence is complete.

[0063] In some embodiments, an individual LP 102 (or 104) may include a sealed housing 110 configured for placement on or attachment to the interior or exterior of a cardiac chamber, and at least two leadless electrodes 108 proximate the housing 110 and configured for bidirectional communication with at least one other device inside or outside the body (e.g., a co-implanted ICD 106).

[0064] refer to Figure 1B , LP 102 (or 104) is shown as optionally including an accelerometer 154, which can be sealed within housing 110. Accelerometer 154 can be any of a variety of different types of known accelerometers, or can be an accelerometer developed in the future. For one example, accelerometer 154 can be or include a MEMS (micro-electromechanical system) multi-axis accelerometer, such as a type that utilizes capacitive or optical cantilever technology, or a piezoelectric accelerometer that uses the piezoelectric effect of certain materials to measure dynamic changes in mechanical variables. In the case where the accelerometer is a multi-axis accelerometer, it can include two or three sensors aligned along orthogonal axes. Accelerometer 154 can be, for example, a one-dimensional (1D) accelerometer (also known as a uniaxial accelerometer), a two-dimensional (2D) accelerometer (also known as a dual-axis accelerometer), or a three-dimensional (3D) accelerometer (also known as a triaxial accelerometer). The output of the accelerometer may be used to determine the orientation of the IMD, and thus, it may be said that the output of the accelerometer (e.g., 154) indicates the orientation of the IMD (e.g., LP 102 or 104). More specifically, according to certain embodiments, the controller 112 of the LP 102 (or 104) receives one or more outputs of the accelerometer 154 that indicate the orientation of the LP 102 (or 104). In such embodiments, the controller 112 may determine the actual orientation of the LP 102 (or 104) based on the outputs received from the accelerometer 154. Each output of the accelerometer 154 may include a corresponding signal.

[0065] One or more signals generated and output by the accelerometer 154 may be analyzed with respect to frequency content, energy, duration, amplitude, and / or other characteristics. Such signals may be amplified and / or filtered or may not be amplified and / or filtered before being analyzed. For example, filtering may be provided using low-pass, high-pass, and / or band-pass filters. The signal output by the accelerometer 154 may be an analog signal that may be analyzed in the analog domain, or may be converted to a digital signal (through an analog-to-digital converter) and analyzed in the digital domain. Alternatively, the signal output by the accelerometer 154 may already be in the digital domain. One or more signals output by the accelerometer 154 may be analyzed by the controller 112 and / or other circuits. In some embodiments, the accelerometer 154 is packaged with an integrated circuit (IC) that is designed to analyze the signals it generates. In such embodiments, one or more outputs of the packaged sensor / IC may 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 (indicative of 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 the digital data. Other variations are possible and within the scope of embodiments of the present technology. According to some embodiments, the LP and / or other IMD lacks the accelerometer 154.

[0066] Figure 1B A single LP 102 (or 104) is depicted, and the functional elements of the LP are shown to be substantially enclosed in a sealed housing 110. The LP 102 (or 104) has at least two electrodes 108 located within, on, 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, for sensing motion, for sensing temperature, and for bidirectional conductive communication with at least one other device inside or outside the body. Sealed feedthroughs 130, 131 conduct electrode signals through the housing 110. The housing 110 contains a primary battery 114 to supply power for pacing, sensing, and communication. The housing 110 also contains circuits 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 sending information to at least one other device via the electrodes 108. Housing 110 may also contain circuitry for monitoring device health, such as battery current monitor 136 and battery voltage monitor 138, and may contain circuitry for controlling operation in a predetermined manner.

[0067] The receivers 120 and 122 may also be referred to as a low frequency (LF) receiver 120 and a high frequency (HF) receiver 122, respectively, because the receiver 120 is configured to monitor one or more signals within a relatively low frequency range (e.g., below 100 kHz), and the receiver 122 is configured to monitor one or more signals within a relatively high frequency range (e.g., above 100 kHz). In some embodiments, the receiver 120 (and more specifically, at least a portion thereof) is always enabled and monitors for a wake-up notification, which may simply be a wake-up pulse within a specific low frequency range (e.g., between 1 kHz and 100 kHz); and the receiver 122 is selectively enabled by the receiver 120. The receiver 120 is configured to consume less power than the receiver 122 when both the first receiver and the second receiver are enabled. Therefore, the receiver 120 may also be referred to as a low power receiver 120, and the receiver 122 may also be referred to as a high power receiver 122. The low power receiver 120 cannot receive signals within a relatively high frequency range (e.g., above 100 kHz), but consumes significantly less power than the high power receiver 122. In this way, the low power receiver 120 is able to always monitor for wake-up notifications without significantly draining the battery of the LP (e.g., 114). According to some embodiments, in response to the low power receiver 120 receiving the wake-up notification, the high power receiver 122 is selectively enabled by the low power receiver 120 so that the high power receiver 122 can receive higher frequency signals and thus handle the higher data throughput required for effective i2i communication without unnecessarily and quickly draining the battery of the LP (which might be the case if the high power receiver 122 were always enabled).

[0068] Because the receivers 120, 122 are used to receive conducted communication messages, the receivers 120, 122 may also be referred to as conducted communication receivers. In some embodiments, each of the LPs 102 includes only a single conducted communication receiver. An example of a single conducted communication receiver that may be included in the LPs and / or other types of IMDs mentioned herein is described in commonly assigned U.S. Patent Application No. 17 / 538,827, filed on December 30, 2021, entitled “Fully-Differential Receiver for Receiving Conducted Communication Signals,” which is incorporated herein by reference.

[0069] The electrodes 108 can be configured to communicate bidirectionally between multiple LPs and / or implanted ICDs 106 to coordinate pacing pulse delivery and optionally other therapeutic or diagnostic features using messages that identify events at the individual LP that initiated the message, and the LP that received the message reacts as indicated by the message based on the source of the message. The LP 102, 104 that receives the event message reacts as indicated by the event message based on the source or location of the message. In some embodiments or conditions, two or more leadless electrodes 108 can be configured to communicate bidirectionally between one or more LPs 102, 104 and / or ICDs 106 and transmit data including a designated code for an event detected or created by an individual LP. Each LP can be configured to emit a unique code corresponding to the type of event and the location of the transmitting pacemaker.

[0070] In addition, the information transmitted on the incoming channel can also include an event message from another leadless cardiac pacemaker indicating that the other leadless cardiac pacemaker has sensed a heartbeat or has delivered a pacing pulse, and identifying the location of the other pacemaker. For example, LP 104 can receive the event message from LP 102 and relay it to the programmer. Similarly, the information transmitted on the outgoing channel can also include a message to another LP or ICD that the sending leadless cardiac pacemaker has sensed a heartbeat or has delivered a pacing pulse at the location of the sending pacemaker.

[0071] Again, refer to Figures 1 and Figure 2 , a cardiac pacing system 100 may include an ICD 106 attached to an LP 102, 104 configured for implantation in electrical contact with a cardiac chamber and for performing cardiac rhythm management functions in combination with the implantable ICD 106. As discussed herein, the implantable ICD 106 and one or more LPs 102, 104 may be configured for leadless intercommunication by conduction of information via body tissue for wireless transmission between a transmitter and a receiver.

[0072] As shown in the illustrative embodiment, the LP 102 , 104 may include two or more leadless electrodes 108 configured for delivering cardiac pacing pulses, sensing induced and / or natural cardiac electrical signals, and bidirectionally communicating with a co-implanted ICD 106 .

[0073] The LPs 102, 104 may be configured to operate in a specific location and in a specific function at the time of manufacture and / or when programmed by an external programmer 109. Bidirectional communications between multiple LPs may be arranged to transmit notification of a sensed heartbeat or delivered pacing pulse event and the coded type and location of the event to another implanted pacemaker or pacemakers. The LP 102, 104 receiving the communication decodes the information and responds according to the location of the receiving pacemaker and the predetermined system function.

[0074] In some embodiments, LPs 102 and 104 are configured to be implantable in or on any chamber of the heart, i.e., the atria (RA, LA) or ventricles (RV, LV). Further, for a dual chamber configuration, multiple LPs may be co-implanted (e.g., one in the RA and one in the RV, or one in the RV and one in the coronary sinus proximal to the LV). Certain pacemaker parameters and functionality depend on (or assume) knowledge of the chamber in which the pacemaker is implanted (and therefore the LP interacts with, e.g., pacing and / or sensing). Some non-limiting examples include: sensing sensitivity, induced response algorithms, use of AF suppression in the local chamber, blanking and refractory periods, etc. Thus, each LP preferably knows the identity of the chamber in which the LP is implanted, and a process may be implemented to automatically identify the local chamber associated with each LP.

[0075] Also like Figure 1B As shown, 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 a shunt 144 to a regulator circuit 146 to produce a positive voltage source 148 suitable for powering the remaining circuits of the pacemaker 102. The shunt 144 enables the battery current monitor 136 to provide an indication of battery current drain and indirectly an indication of device health to the controller 112. An illustrative power source may be the primary battery 114.

[0076] In various embodiments, the LP 102, 104 can manage power consumption to draw limited power from the battery, thereby reducing the size of the device. Each circuit in the system 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. The recharging of the tank capacitor is typically controlled by a charge pump circuit. In a specific embodiment, the charge pump circuit is throttled to recharge the tank capacitor at a constant power from the battery.

[0077] In some embodiments, a controller 112 in one LP 102, 104 can access the signals on the electrodes 108 and can examine the output pulse duration from another pacemaker for use as a signature for determining the validity of the trigger information and, for a signature arriving within predetermined limits, activate the delivery of a pacing pulse after a predetermined delay of zero or more milliseconds. The predetermined delay can be preset at the time of manufacture, programmed via an external programmer, or determined by adaptive monitoring to facilitate identification of the trigger signal and to distinguish the trigger signal from noise. In some embodiments or under some conditions, the controller 112 can examine the output pulse waveform from another leadless cardiac pacemaker for use as a signature for determining the validity of the trigger information and, for a signature arriving within predetermined limits, activate the delivery of a pacing pulse after a predetermined delay of zero or more milliseconds.

[0078] In some embodiments, the electrodes of the LPs 102, 104 may be used to sense an intracardiac electrocardiogram (IEGM), which may detect atrial and / or ventricular activity, for example, by detecting QRS complexes and / or P waves. Since the orientation of the LPs 102, 104 relative to each other and the distance between the LPs 102, 104 may change throughout each cardiac cycle, the LPs 102, 104 may also use such IEGM to time when communication pulses should be generated. In other words, the LPs may utilize the sensed IEGM to determine timing relative to the cardiac cycle.

[0079] Figure 2 LP 102, 104 are shown. LP can include a sealed housing 202 (e.g., housing 110 in FIG. 1) with electrodes 108a and 108b disposed thereon. As shown, electrode 108a can be separate from but partially surrounded by a fixation mechanism 205, and electrode 108b can be disposed on housing 202. Fixation mechanism 205 can be a fixation helix, a plurality of hooks, barbs, or other attachment features configured to attach the pacemaker to tissue (e.g., cardiac tissue). Electrodes 108a and 108b are Figure 1B As shown and referenced in Figure 1B Examples of electrodes 108 discussed above. When the electrodes are used to deliver stimulation, one of the electrodes 108 (e.g., 108a) can be used as a cathode-type electrode and another of the electrodes 108 (e.g., 108b) can be used as an anode-type electrode, or vice versa. For the purposes of this discussion, electrode 108a will generally be referred to as a button electrode 108a (or tip electrode 108a), and electrode 108b will generally be referred to as a ring electrode 108b.

[0080] The housing 202 may also include an electronics compartment 210 within the housing that contains the electronic components necessary for operation of the pacemaker, including, for example, a pulse generator, a receiver, a battery, and a processor for operation. The sealed housing 202 may be suitable for implantation on or in a human heart, and may be, for example, cylindrical, rectangular, spherical, or any other suitable shape.

[0081] The housing 202 may include a conductive, biocompatible, inert, and anodically safe material, such as titanium, 316L stainless steel, or other similar material. The housing 202 may also include an insulator disposed on the conductive material to separate the electrodes 108a and 108b. The insulator may be an insulating coating on a portion of the housing between the electrodes and may include a material such as silicone, polyurethane, parylene, or another biocompatible electrical insulator commonly used in implantable medical devices. Figure 2 In an embodiment, a single insulator 208 is disposed along a portion of the housing between electrodes 108a and 108b. In some embodiments, the housing itself may include an insulator rather than a conductor, such as alumina ceramic or other similar material, and the electrodes may be disposed on the housing.

[0082] like Figure 2 As shown, the pacemaker may also include a header assembly 212 for isolating electrodes 108a and 108b. Header assembly 212 may be made of PEEK, tecothane, or another biocompatible plastic, and may include a ceramic to metal feedthrough, a glass to metal feedthrough, or other suitable feedthrough insulators known in the art.

[0083] Electrodes 108a and 108b may include pacing / sensing electrodes or return electrodes. A low polarization coating 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 2 In the embodiment of the present invention, electrode 108a can be a pacing / sensing electrode and electrode 108b can be a return electrode. Electrode 108b can be a portion of conductive housing 202 that does not include insulator 208.

[0084] Several techniques and structures can be used to attach the housing 202 to the inner or outer wall of the heart. The helical fixation mechanism 205 can enable endocardial or epicardial insertion of the device through a guide catheter. A twistable catheter can be used to rotate the housing and force the fixation device into the heart tissue, thereby inserting the fixation device (and Figure 2Electrode 108a) in the pacing device is fixed in contact with the stimulable tissue. Electrode 108b can be used as an indifferent electrode for sensing and pacing. The fixing mechanism can be partially or fully coated for electrical insulation, and a steroid eluting matrix can be included on or near the device to minimize fibrotic response, as is known in conventional pacing electrode leads.

[0085] Implant-to-implant event messaging

[0086] LP 102 and 104 can coordinate the operation of each other in various ways using implant-to-implant (i2i) communication via event messages. The terms i2i communication, i2i event message, and i2i event marker are used interchangeably herein to refer to event-related messages and IMD / IMD operation-related messages sent from an implanted device and directed to another implanted device (although an external system (e.g., a programmer) can also receive i2i event messages). In some embodiments, LP 102 and LP 104 operate as two independent leadless pacemakers that maintain beat-to-beat dual-chamber function via a "master / slave" operating configuration. For the purposes of description, the ventricular LP 104 should generally be referred to as a "vLP" and the atrial LP 102 should generally be referred to as an "aLP." An LP 102 or 104 designated as a master device (e.g., a vLP) can implement all or most dual-chamber diagnostic and treatment determination algorithms. For the purposes of the following description, it is assumed that the vLP is the "master" device and the aLP is the "slave" device. Alternatively, the aLP may be designated as the master device and the vLP may be designated as the slave device.The master device coordinates most or all decisions and timing determinations (including, for example, rate response changes).

[0087] According to certain embodiments, a method for coordinating operations between a first LP and a second LP is provided, the first LP and the second LP being configured to be implanted entirely within a first chamber and a second chamber of a heart. Alternatively, it is possible that the LP is implanted outside of a cardiac chamber, rather than within the cardiac chamber. In certain embodiments, a method uses conducted communication through electrodes positioned along a housing of a first LP to transmit an event marker, wherein the event marker indicates one of a local pacing event or a sensing event. The method detects the event marker at the second LP on a sensing channel. The method identifies the event marker at the second LP based on a predetermined pattern, the predetermined pattern being configured to indicate that an event of interest has occurred in a remote chamber. In response to the identification operation, the method initiates a related action in the second LP.

[0088] Figure 3 3 is a timing diagram 300 showing one example of conducted i2i communication for a pacing event. The i2i communication may be sent, for example, from LP 102 to LP 104. Figure 3As shown, in this embodiment, an i2i transmission 302 is sent before a pacing pulse 304 is delivered by a transmitting LP (e.g., LP102). This enables a receiving LP (e.g., LP104) to prepare for remote delivery of a pacing pulse. The i2i transmission 302 includes an envelope 306, which may include one or more individual pulses. For example, in this embodiment, the envelope 306 includes a low frequency pulse 308 followed by a high frequency pulse train 310. The low frequency pulse 308 lasts for a period of time T i2iLF , and the high frequency pulse train 310 lasts for a period of time T i2iHF The end of the low frequency pulse 308 and the beginning of the high frequency pulse train 310 are separated by a gap period T i2iGap separate.

[0089] like Figure 3 As shown, the i2i transmission 302 lasts for a period of time T i2iP , and the pacing pulse 304 lasts for a period of time Tpace. The end of the i2i transmission 302 and the start of the pacing pulse 304 are delayed by a period of time T delayp The delay period may be, for example, between about 0.0 and 10.0 milliseconds (msec), particularly between about 0.1 msec and 2.0 msec, and more particularly about 1.0 msec. As used herein, the terms about and approximately mean + / - 10% of a specified value.

[0090] Figure 4 4 is a timing diagram 400 showing an example of i2i communication for a sensing event. The i2i communication may be sent, for example, from LP 102 to LP 104. Figure 4 As shown, in this embodiment, when the sensed intrinsic activation 402 crosses the sensing threshold 404, the transmitting LP (eg, LP 102) detects the sensing event. A predetermined delay period T after the detection delayS After that, LP is sent for a predetermined period of time T. i2iS The i2i transmission 406. The delay period may be, for example, between about 0.0 and 10.0 milliseconds (msec), particularly between about 0.1 msec and 2.0 msec, and more particularly about 1.0 msec.

[0091] As with i2i transmission 302, i2i transmission 406 may include an envelope, which may include one or more individual pulses. For example, similar to envelope 306, the envelope of i2i transmission 406 may include a low frequency pulse followed by a high frequency pulse train.

[0092] According to some embodiments, the time period T i2iP and T i2iSThe duration of each of the 308 pulses may be in the range of 1.5 msec to 13 msec, and more preferably, in the range of 2.0 msec to 5.0 msec. The duration includes a low frequency pulse (e.g., 308) and a high frequency pulse train (e.g., 310 following the low frequency pulse). The low frequency pulse (e.g., 308) may be used as a wake-up pulse, and the high frequency pulse train (e.g., 310 following the low frequency pulse) may be used as a communication event marker and payload.

[0093] Where i2i communication is provided using conductive communication, it will generally be more specifically referred to herein as conductive i2 communication, or equivalently as i2i conductive communication. It should also be noted that phase conductive communication is generally used interchangeably with phase conductive communication.

[0094] 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 marker 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 markers may be sent after the corresponding AS or AP events. Alternatively, the first LP may send the AP event marker slightly before delivering the atrial pacing pulse. In the case where the first LP is located in the atrium and the second LP is located in the ventricle, the second LP may initiate an atrioventricular (AV) interval after receiving the AS or AP event marker from the first LP; and may initiate a post-atrial ventricular blanking (PAVB) interval after receiving the AP event marker from the first LP.

[0095] Alternatively, the first and second LPs may operate in a "pure" master / slave relationship, where the master LP delivers "command" tags in addition to or instead of "event" tags. The command tags instruct the slave LP to perform an action such as delivering a pacing pulse. For example, when the slave LP is located in the atrium and the master LP is located in the ventricle, in a pure master / slave relationship, the slave LP delivers an immediate pacing pulse to the atrium upon receiving an AP command tag from the master LP.

[0096] According to some embodiments, communication and synchronization between the aLP and vLP is achieved via conducted communication of markers / commands in event messages (according to the i2i communication protocol). According to certain embodiments, conducted communication refers to event messages sent from sensing / pacing electrodes at frequencies outside the RF or Wi-Fi frequency range. Such conducted communication relies on electrical communication signals or pulses that are "conducted" through the patient's body (more specifically, through the patient's tissue). The following figures and corresponding descriptions illustrate non-limiting examples of markers that may be sent in event messages. The following figures and corresponding descriptions also include examples of results and descriptions of markers that occur in the LP receiving the event message. Table 3 represents exemplary event markers sent from the aLP to the vLP, while Table 4 represents exemplary event markers sent from the vLP to the aLP. In a master / slave configuration, an AS event marker is sent from the aLP each time an atrial event is sensed outside of the post-ventricular atrial blanking (PVAB) interval or some other alternatively defined atrial blanking period. An AP event marker is sent from the aLP each time the aLP delivers a pacing pulse in the atrium. The aLP may limit the transmission of the AS markers, whereby the aLP sends an AS event marker when an atrial event is sensed both outside the PVAB interval and outside the ventriculoatrial refractory period after (PVARP) or some other alternatively defined atrial refractory period. Alternatively, the aLP may not limit the transmission of the AS event markers based on the PVARP, but instead send an AS event marker every time an atrial event is sensed.

[0097]

[0098] As shown in Table 3, when the aLP sends an event message including an AS event marker (indicating that the aLP sensed an intrinsic atrial event), the vLP starts the AV interval timer. If the aLP sends AS event markers for all sensed events, the vLP will preferably first determine that the PVAB or PVARP interval is inactive before starting the AV interval timer. However, if the aLP sends AS event markers only 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 marker without first checking the PVAB or PVARP status. When the aLP sends an AP event marker (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 time, provided that the PVARP interval is inactive. The vLP can also blank its sense amplifier to prevent possible crosstalk sensing of remote pacing pulses delivered by the aLP.

[0099]

[0100] As shown in Table 4, when the vLP senses a ventricular event, the vLP sends an event message including a VS event marker, in response to which the aLP may start the PVARP interval timer. When the vLP delivers or is about to deliver a pacing pulse in the ventricle, the vLP sends a VP event marker. When the aLP receives the VP event marker, the aLP starts the PVAB interval timer as well as the PVARP interval timer. The aLP may also blank its sense amplifier to prevent possible crosstalk sensing of remote pacing pulses delivered by the vLP. The vLP may also send an event message containing an AP command marker to command the aLP to deliver an immediate pacing pulse in the atrium when the command is received without delay.

[0101] The aforementioned event markers are examples of a subset of markers that can be used to enable 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 that are implemented locally within the aLP, such as PVAB. In this embodiment, the aLP is effectively considered a remote "wireless" atrial pacing / sensing electrode. In another embodiment, the vLP can execute most but not all 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-making responsibility can be divided solely to one of the aLP or vLP. In other embodiments, decision-making responsibility can involve joint inputs and responsibilities.

[0102] In an embodiment, to provide safer therapy, ventricular-based pacing and sensing functions are not dependent on any i2i communications. For example, in the event of a loss (extended or transient) of LP-to-LP (i2i) communications, the system 100 can automatically revert to safe ventricular-based pacing / sensing functions because the vLP device is running all necessary algorithms to implement these functions independently. For example, the vLP can revert to VVI mode because the vLP does not rely on i2i communications to perform ventricular pacing / sensing activities. Once i2i communications are restored, the system 100 can automatically restore dual-chamber functionality.

[0103] In some embodiments, an LP (or another type of IMD) that receives any i2i communication from another LP (or another type of IMD) or from an external system may send a receipt confirmation (ACK) indicating that the receiving LP / IMD received the i2i communication, etc. In some embodiments, a first LP (or another type of IMD) that sends an i2i communication to a second LP (or another type of IMD) may determine an i2i communication failure if the first LP (or another type of IMD) does not receive an ACK from the second LP (or another type of IMD) to which the i2i communication was sent within a specified window after transmission of the i2i communication or in the next i2i communication received from the second LP (or another type of IMD).

[0104] As explained herein, communication and synchronization between aLP and vLP is achieved via conducted communication of event markers (according to the i2i communication protocol). In certain embodiments, the i2i communication marker may be emitted only substantially simultaneously with a local pacing or sensing event. Therefore, there is no risk of emitting a marker during a vulnerable period, and therefore there is no risk of inducing an unexpected excitation. The i2i communication event marker is optionally extended with a code to indicate whether the transmitting device has successfully received a valid i2i marker from the remote LP since the last transmission from the remote LP. For example, a simple example of this encoding uses a binary indicator (e.g., 0 / 1, ACK / nACK, etc.). Alternatively, a more complex encoding scheme may be employed to include extended information, such as the number of consecutively lost markers, handshakes to provide insight into which marker(s) are lost, etc. These "confirmation codes" can be used by both LPs to diagnose bidirectional and / or unidirectional faults in i2i communications so that the LPs can take remedial actions appropriately. One such remedial action (e.g., for a momentary loss of i2i communications) would be to "bridge" one or more lost / corrupted flags for n future cycles before reverting to a "protection" mode. Another such remedial action (e.g., for a longer period of loss of i2i communications) would be to revert to a protection pacing mode in order to reduce and preferably minimize the likelihood of asynchronous pacing by the aLP and vLP.

[0105] One example of a protection mode is a transition from dual chamber DDD operation functionality to ventricular VVI pacing functionality only. Once bidirectional i2i communication has been reestablished, the LP will exit from protection mode and return to the programmed dual chamber mode. As another example of an alternative protection mode, the aLP and vLP may transition from jointly providing DDD operation to providing VDD operation when the LP experiences a unidirectional loss of v2a i2i communication (i.e., a2v i2i communication remains intact).

[0106] As described above, one of the challenges when performing pacing and / or sensing operations in the RA and RV using a pair of LPs (e.g., 102, 104) is the reliance on i2i communication to maintain proper synchronization between the RV and RA. As also described above, the transmitter (e.g., 118) of the LP 102, 104 can be configured to send event messages in a manner that does not inadvertently capture the heart in the chamber where the LP 102, 104 is located (e.g., when the associated chamber is in a refractory state). In addition, the LP 102, 104 that receives the event message can enter an "event refractory" state (or event blanking state) after receiving the event message. The event refractory / blanking state can be set to extend a determined time period after receiving the event message in order to avoid the receiving LP 102, 104 from inadvertently sensing another signal as an event message that could otherwise cause a re-trigger. For example, the receiving LP 102, 104 can detect a conducted communication pulse from another LP 102, 104. The amplitude of the detected (i.e., sensed) conducted communication pulse can be referred to as the sensed amplitude.

[0107] As described above, i2i conducted communication may be adversely affected by the orientation of the LPs relative to each other and the distance between the LPs. Both computer simulations and animal testing have shown that the sensed amplitude varies widely with different orientation angles between the LPs. For example, in a case where a first LP (e.g., 102) sends a pulse with a pulse amplitude of 2.5V to a second LP (e.g., 104), the sensed amplitude of the pulse received by the second LP (e.g., 104) may vary from approximately 2mV to less than 0.5mV, depending on the orientation between the first LP and the second LP (e.g., 102 and 104). For example, in a case where LP 102 is implanted in the right atrium (RA) and LP 104 is implanted in the left atrium (LA), for example, Figure 1A As shown, the distance between and the orientation of LPs 102 and 104 relative to each other may change during the course of each cardiac cycle. In addition, the orientation and distance of LPs 102 and 104 relative to each other may be affected by the patient's posture. Therefore, since the sensed amplitude of a pulse received by one LP (e.g., 104) from another LP (e.g., 102) may vary significantly based on the distance between the LPs and the orientation of the LPs relative to each other, the sensed amplitude may vary significantly depending on the timing of sending pulses (conducted communication pulses) during the cardiac cycle and the patient's posture when the pulses are sent.

[0108] For example, assuming that the LP 102, 104 has a sensing threshold of 0.5 mV, this means that the sensed pulse must have an amplitude of at least 0.5 mV in order to be detected as a communication pulse by the receiving LP. In other words, if the sensed amplitude of the received communication pulse is below the sensing threshold, the receiving LP will not be able to receive the information encoded therein and may not be able to respond accordingly, which is undesirable.

[0109] Figure 5 is used to show how to quantify Figure 5 FIG. 1 is a diagram of the orientations of two different LPs (eg, 102, 104) labeled LP 2 and LP 1 in FIG. Figure 5 , LP2 (eg, 102) is shown as having axis 502, and LP1 (eg, 104) is shown as having axis 504. Line D12 represents the distance between the tip electrodes of LP1 and LP2. Figure 5 , angle α12 is the angle between axis 504 of LP1 and line D12; angle β12 is the angle between axis 502 of LP2 and line D12; and angle γ12 is the angle between a plane defined by angle α12 and a plane defined by angle β12.

[0110] Table 5 below provides the results of a simulation showing how the sensed amplitude is affected by the orientation of LP1 and LP2 relative to each other, where LP2 is assumed to be implanted in the RA, LP1 is assumed to be implanted in the RV, and distance D12 is assumed to be fixed at 124 millimeters (mm). In Table 5, it is assumed that the distance D12 between LP1 and LP2 remains constant so that only the orientation of LP1 and LP2 relative to each other can be analyzed. Since distance D12 is the distance between the button (also called tip) electrodes of LP1 and LP2, distance D12 may also be referred to herein as LP1 button-LP2 button distance.

[0111]

[0112] The first row of Table 5 shows that when the angle β12 (i.e., the angle between the axis 502 of LP2 and the line D12) is 12 degrees, in response to LP2 sending a communication pulse with an amplitude of 2.5V, the sensed amplitude of the communication pulse received by LP1 will be 2.13mV, which is much higher than the 0.5mV sensing threshold. In contrast, the sixth row of Table 5 shows that when the angle β12 is 92 degrees, in response to LP2 sending a communication pulse with an amplitude of 2.5V, the sensed amplitude of the communication pulse received by LP1 will be only 0.198mV, which is much lower than the 0.5mV sensing threshold. Looking at the rightmost column and first row of Table 5 shows that when the angle β12 is 12 degrees, in response to LP1 sending a communication pulse with an amplitude of 2.5V, the sensing amplitude of the communication pulse received by LP2 will be 2.11mV, which is much higher than the 0.5mV sensing threshold; and when the angle β12 is 92 degrees, in response to LP1 sending a communication pulse with an amplitude of 2.5V, the sensing amplitude of the communication pulse received by LP2 will be only 0.198mV, which is much lower than the 0.5mV sensing threshold.

[0113] In case of larger heart size, the sensed amplitude decreases. More specifically, a larger heart can result in an increase in the distance D12 between LP1 and LP2, the results are summarized in Table 6 below.

[0114]

[0115] The results summarized in Table 6 simulate the worst case with the heart size at the upper limit (D12 ~ 150mm). It can be understood from the comparison between Table 6 and Table 5 that the sensing amplitude decreases as D12 increases from 124mm to 150mm, so that in Table 6, when the angle β12 is greater than 52 degrees, the sensing amplitude is below the 0.5mV sensing threshold. Therefore, it can be understood that the conducted i2i communication between LPs implanted in larger hearts is more adversely affected by the relative orientation of the LPs than in smaller hearts. It can be understood from Table 6 that i2i communication may be adversely affected by the distance between the LPs.

[0116] When performing i2i communication, the pulse or pulses sent from one LP to another LP may be more generally referred to as i2i signals. Due to the nature of the electrode potential distribution, the bipolar sensing of the i2i signal (by the LP receiving / sensing the i2i signal) is minimal along the equipotential lines and maximal along the lines orthogonal to the equipotential lines. In other words, when the corresponding axes of the two LPs (communicating with each other) (e.g., Figure 5 502 and 504) are aligned with each other, the sensed i2i signal is close to its maximum value, and when the corresponding axes of the two LPs (e.g., Figure 5 When 502 and 504 in FIG. 1 are orthogonal to each other, the sensed i2i signal is close to its minimum value.

[0117] For the purposes of this discussion, a LP may be said to be within the "deaf zone" when the LP is oriented relative to another LP such that (for a given transmitted communication pulse amplitude) the sensed amplitude of a communication pulse received by the LP will be below a sensing threshold (e.g., 0.5 mV). This is because in this situation, the LPs cannot successfully communicate with or "hear" each other, even if they are attempting to communicate with or "talk" to each other.

[0118] For the purposes of this discussion, it is assumed that a dual-chamber LP system includes a vLP implanted in or on a ventricular chamber (e.g., the right ventricular chamber) and an aLP implanted in or on an atrial chamber (e.g., the right atrial chamber). In such an LP system, the distance and relative orientation between the vLP and the aLP vary during the cardiac cycle. When the heart is filled with blood, the heart is at its largest volume, and the vLP and aLP are typically relatively far apart. In contrast, when the heart contracts, the vLP and aLP are closer to each other and their orientation relative to each other changes. Certain embodiments of the present technology described herein take advantage of the fact that when the heart (in which and / or on which the LP is implanted) contracts, the distance between the LPs typically decreases and the orientation between the LPs changes. The distance between the LPs and the orientation of the LPs relative to each other are two parameters that affect the success of conducted i2i communication.

[0119] Monitor and adjust AV sync

[0120] As described above, the aLP (e.g., 102) and the vLP (e.g., 104) may be configured to jointly provide DDD operation when there is successful bidirectional i2i communication, i.e., when the vLP successfully receives a2v messages from the aLP and the aLP successfully receives v2a messages from the vLP. However, due to a variety of different reasons, there may be periods of time when bidirectional i2i communication fails because the vLP 104 fails to successfully receive one or more a2v messages from the aLP 102, and / or the aLP 102 fails to successfully receive one or more v2a messages from the vLP 104. Such failures in i2i communication may occur, for example, due to noise and / or the relative orientation and / or distance between the aLP 102 and the vLP 104, but is not limited thereto.

[0121] Furthermore, as explained above in the discussion of Table 2, in a dual-chamber LP system including an aLP and a vLP configured to jointly provide DDD operation, if a2v communication is lost (i.e., the vLP 104 does not successfully receive one or more a2v messages sent by the aLP 102), the vLP 104 stops tracking atrial activity, and the dual-chamber LP system effectively provides DDI operation. If v2a communication is lost (i.e., one or more v2a messages sent by the vLP are not successfully received by the aLP), the aLP 102 stops pacing, and the dual-chamber LP system effectively provides VDD operation. If i2i communication is lost in both directions simultaneously (i.e., the v2a messages sent by the vLP 104 are not successfully received by the aLP 102, and the a2v messages sent by the aLP 102 are not successfully received by the vLP 104), both mitigations are in effect, and the dual-chamber LP system effectively provides VDI operation. These transmit-receive protection measures are used to guarantee RV pacing while maintaining RA tracking and RA pacing as much as possible.

[0122] Additionally, as described above, certain embodiments of the technology described herein calculate an estimate of the frequency at which a dual-chamber LP system (including an aLP and a vLP) provides programmed DDD operation and provides each of one or more protection types of operation (e.g., VDD, DDI, and / or VDI). Additionally, certain embodiments of the technology described herein calculate an estimate of the time (also referred to as cumulative duration) that the dual-chamber LP system provides AV synchronization. Furthermore, according to certain embodiments of the technology described herein, at least one parameter used by the aLP to send additional a2v messages to the vLP, at least one parameter used by the vLP to receive additional a2v messages from the aLP, at least one parameter used by the vLP to send additional v2a messages to the aLP, and / or at least one parameter used by the aLP to receive additional v2a messages from the vLP is adjusted based on the estimated AV synchronization. Additional details of such embodiments are now described below.

[0123] FIG. 6A to FIG. 6Cis a high-level flow chart for summarizing certain embodiments of the present technology for determining and using an AV synchronization metric that specifies an estimate of how often AV synchronization is achieved during a time period during which an aLP (e.g., 102) and a vLP (e.g., 104) of a dual-chamber LP system (e.g., 100) are configured to jointly provide a DDD operation when, during a cardiac cycle within the time period, the vLP successfully receives an a2v message sent by the aLP and a v2a message sent by the vLP is successfully received by the aLP. Additionally, in the dual-chamber LP system, the aLP and the vLP are configured to jointly provide at least one of a VDD operation, a DDI operation, or a VDI operation when, during at least some of the occurrences of at least one of an a2v message sent by the aLP and / or an a2a message sent by the vLP not being successfully received by the vLP during another cardiac cycle within the time period.

[0124] As described above, for the purposes of this discussion, when the aLP successfully detects and decodes a v2a message, the aLP is considered to have successfully received a v2a message, and when the vLP successfully detects and decodes a v2a message, the vLP is considered to have successfully received an a2v message.

[0125] refer to Fig. 6A , step 602 involves obtaining a2v throughput, v2a throughput, and event sequence information during a time period in which the aLP and vLP are configured to jointly provide DDD operations. If the AV synchronization metric (determined at step 606) is used to adjust the implantation position of the aLP and / or vLP during the implantation surgery, the time period can be relatively short, such as a few minutes. Alternatively, if the AV synchronization metric (determined at step 606) is used to adjust one or more transmission and / or reception parameters, the time period can be much longer, for example, one or more hours, days, weeks, or months, but not limited to this. According to certain embodiments, the time period starts when data was last cleared from the memories of the aLP and vLP, and ends when data is retrieved from the memories of the aLP and vLP. Other variations are also possible and within the scope of the embodiments described herein.

[0126] According to certain embodiments, aLP tracks how many a2v messages aLP has sent to vLP during the time period (during which aLP and vLP are configured to jointly provide DDD operations), and aLP tracks how many v2a messages aLP has received from vLP during the time period. In addition, vLP tracks how many v2a messages vLP has sent to aLP during the time period, and vLP tracks how many a2v messages vLP has received from aLP during the time period. Both the above information tracked by aLP and the above information tracked by vLP can be uploaded to an external programmer, and based on such uploaded information, the external programmer can determine the a2v throughput and the v2a throughput. For example, if aLP sent one hundred a2v messages during the time period, and vLP received ninety a2v messages, the programmer can determine that the a2v throughput is 90%. For another example, if vLP sent one hundred v2a messages during the time period, and aLP received eighty-five v2a messages, the programmer can determine that the v2a throughput is 85%. Instead of the programmer determining the a2v throughput and the v2a throughput, the aLP may send its tracked information to the vLP, and the vLP uses its tracked information plus the information tracked by the aLP (which is provided to the vLP by the aLP), and the vLP determines the a2v throughput and the v2a throughput. Alternatively or additionally, the vLP may send its tracked information to the aLP, and the aLP uses its tracked information plus the information tracked by the vLP (which is provided to the aLP by the vLP), and the aLP determines the a2v throughput and the v2a throughput. In some embodiments, the aLP continuously monitors and stores (in its memory or registers) the a2v throughput, and the vLP continuously monitors and stores (in its memory or registers) the v2a throughput. In some embodiments, the a2v throughput and the v2a throughput obtained at step 602 may be provided by an external system, such as an external programmer (e.g., 109) that uploads the a2v throughput from the aLP and the v2a throughput from the vLP. Other types of external systems (also referred to as non-implanted systems) that may perform step 602 include, but are not limited to, bedside monitors, patient link modules, and remote patient care networks (PCNs) that may receive such information from external programmers. As will be appreciated from the description herein, other variations are possible and within the scope of the embodiments described herein. Note that step 602 may include multiple sub-steps, for example, including a sub-step of obtaining a2v throughput, a sub-step of obtaining v2a throughput, and a sub-step of obtaining event sequence information, wherein these sub-steps need not be performed simultaneously.

[0127] In certain embodiments, the event sequence information includes AP-VP information, AP-VS information, AS-VP information, and AS-VS information. In such an embodiment, the AP-VP information specifies the frequency of providing atrial pacing (AP) and ventricular pacing (VP) for the same cardiac cycle aLP and vLP for the same cardiac cycle during the time period. The AP-VS information specifies the frequency of providing AP and ventricular sensing (VS) for the same cardiac cycle aLP and vLP for the same cardiac cycle during the time period. The AS-VP information specifies the frequency of providing atrial sensing (AS) and VP for the same cardiac cycle aLP and vLP for the same cardiac cycle during the time period. The AS-VS information specifies the frequency of providing AS and VS for the same cardiac cycle aLP and vLP for the same cardiac cycle during the time period. The following discussed Fig.11 and Fig.12 is a graphical representation of the sample distribution of event sequence information. Fig.11 and Fig.12 It will be appreciated that the event sequence information may also specify the frequency with which the PVC occurs during the time period.

[0128] In some embodiments, one or both of the aLP or the vLP tracks and stores event sequence information. An external programmer (e.g., 109) and / or some other external system may obtain event sequence information from the vLP and / or the aLP when the external system queries or otherwise uploads information from the vLP and / or the aLP. In a particular embodiment, when the external programmer queries the vLP and the aLP, the vLP sends the event sequence information in terms of counts (AP-VP counts, AP-VS counts, AS-VP counts, and AS-VS counts) grouped by atrioventricular (AV) delay (which may be used to construct an AV delay histogram) to the external programmer, and the external programmer sums the counts for all bins for each event sequence (AP-VP, AP-VS, AS-VP, and AS-VS) and then converts the sum of the counts for each event sequence into a percentage, an example of which may be found at. Fig.11 and Fig.12 Other variations are possible and within the scope of the embodiments described herein. For example, if reference is made to Figure 6B Where the outlined method is performed by a vLP, there may be no need for the vLP to upload sequence of events information to an external programmer or other external system, as the vLP itself uses such information.

[0129] Still reference Fig. 6A, step 604 involves determining an estimated DDD metric, an estimated VDD metric, an estimated DDI metric, and an estimated VDI metric within the time period (during which aLP and vLP are configured to jointly provide DDD operations) based on the a2v throughput and the v2a throughput. In some embodiments, the estimated DDD metric specifies an estimate of the frequency at which aLP and vLP jointly provide DDD operations during the time period when aLP and vLP are configured to jointly provide DDD operations. The estimated VDD metric specifies an estimate of the frequency at which aLP and vLP jointly provide VDD operations during the time period. The estimated DDI metric specifies an estimate of the frequency at which aLP and vLP jointly provide DDI operations during the time period. The estimated VDI metric specifies an estimate of the frequency at which aLP and vLP jointly provide VDI operations during the time period. Note that step 604 may include multiple sub-steps, for example, including a sub-step of determining an estimated DDD metric, a sub-step of determining an estimated VDD metric, a sub-step of determining an estimated DDI metric, and a sub-step of determining an estimated VDI metric, wherein these sub-steps do not need to be performed simultaneously, but may be performed continuously one after another, but are not limited thereto.

[0130] According to certain embodiments, Table 7 shown below or the information included therein is used to determine an estimated DDD metric, an estimated VDD metric, an estimated DDI metric, and an estimated VDI metric. More specifically, Table 7 indicates: which combinations of event sequences (AP-VP, AP-VS, AS-VP, and AS-VS) and operating modes (DDD, VDD, DDI, VDI) can successfully provide AV synchronization (as represented by "S" for synchronization), during which the atrial and ventricular chambers of the patient's heart contract in a coordinated manner relative to each other; and which combinations of event sequences and operating modes result in AV dyssynchrony (as represented by "D" for dyssynchrony), during which the atrial and ventricular chambers of the patient's heart contract in an uncoordinated manner relative to each other.

[0131]

[0132] As can be understood from Table 7, as long as aLP and vLP jointly provide DDD operation, AV synchronization is achieved regardless of which of the AP-VP, AP-VS, AS-VP, or AS-VS event sequences is provided. In contrast, when aLP and vLP jointly provide VDD operation, AV synchronization is achieved if the AS-VP or AS-VS event sequence is provided, but AV synchronization is not achieved if the AP-VP or AP-VS event sequence is provided. When aLP and vLP jointly provide DDI operation, AV synchronization is achieved if the AP-VP, AP-VS, or AS-VS event sequence is provided, but AV synchronization is not achieved if the AS-VP event sequence is provided. When aLP and vLP jointly provide VDI operation, AV synchronization is achieved if the AS-VS event sequence is provided, but AV synchronization is not achieved if the AP-VP, AP-VS, or AS-VP event sequence is provided.

[0133] Table 2 discussed above is used to explain that in a dual-chamber LP system including an aLP and a vLP configured to jointly provide DDD operation, if a2v communication is lost (i.e., the vLP does not successfully receive one or more a2v messages sent by the aLP), the vLP stops tracking atrial activity and the dual-chamber LP system effectively provides DDI operation. If v2a communication is lost (i.e., one or more v2a messages sent by the vLP are not successfully received by the aLP), the aLP stops pacing and the dual-chamber LP system effectively provides VDD operation. If i2i communication is lost in both directions simultaneously (i.e., one or more v2a messages sent by the vLP are not successfully received by the aLP, and one or more a2v messages sent by the aLP are not successfully received by the vLP), both mitigations are in effect and the dual-chamber LP system effectively provides VDI operation. These transmission reception protection measures are used to guarantee RV pacing while maintaining RA tracking and RA pacing as much as possible.

[0134] Brief reference Figure 7-9 , the estimated DDD metric may correspond to an estimated DDDmax metric, an estimated DDDmin metric, and / or an estimated DDDrange. The estimated DDDmax metric (which may also be more succinctly referred to herein as DDDmax) is an estimate of the maximum value of the frequency at which the dual-chamber LP system achieves DDD operation during the time period being analyzed, the estimate being based on the a2v throughput and the v2a throughput. The estimated DDDmax metric may correspond to the maximum possible overlap in successful a2v and v2a communications, which occurs when there is a minimum possible overlap in unsuccessful (i.e., lost) a2v and v2a communications, as seen from Figure 8It can be understood. More specifically, the DDDmax metric is equal to the minimum of the a2v throughput and the v2a throughput, which can be expressed using the equation DDDmax metric=min(a2v throughput, v2a throughput). Once the DDDmax metric is determined, the corresponding VDD metric, the corresponding DDI metric, and the corresponding VDI metric can be determined. The corresponding VDD metric is equal to the a2v throughput minus DDDmax, which can be expressed using the equation VDD metric=a2v throughput-DDDmax metric. The corresponding DDI metric is equal to the v2a throughput minus the DDDmax metric, which can be expressed using the equation DDI metric=v2a throughput-DDDmax. The corresponding VDI metric corresponds to the remainder of the period in which any of the DDD, VDD, or DDI operations is not provided. In other words, the corresponding VDI metric is equal to 100% minus the sum of the DDDmax metric, the VDD metric, and the DDI metric, which can be expressed using the equation VDI metric=100%-sum(DDDmax, VDD metric, DDI metric).

[0135] For example, assume that the a2v throughput is equal to 90% (meaning that 90% of the a2v messages sent by the aLP are successfully received by the vLP), and the v2a throughput is equal to 80% (meaning that 80% of the v2a messages sent by the vLP are successfully received by the aLP). Using the above equations, the DDDmax, VDD, DDI, and VDI metrics can be determined as follows. DDDmax metric = min(a2v throughput, v2a throughput) = min(80%, 90%) = 80%. VDD metric = a2v throughput - DDDmax metric = 80% - 80% = 0%. DDI metric = v2a throughput - DDDmax = 90% - 80% = 10%. VDI metric = 100% - sum(DDDmax, VDD metric, DDI metric) = 100% - sum(80% + 0% + 10%) = 100% - 90% = 10%.

[0136] As described above, the estimated DDD metric may alternatively (or additionally) correspond to an estimated DDDmin metric, which may also be more succinctly referred to herein as DDDmin, and is an estimate of the minimum value of the frequency with which the dual-chamber LP system achieves DDD operation during the time period being analyzed, the estimate being based on the a2v throughput and the v2a throughput. The estimated DDDmin metric may correspond to the minimum possible overlap in successful a2v and v2a communications, which occurs when there is a maximum possible overlap in unsuccessful (i.e., lost) a2v and v2a communications, as seen from Fig. 9Understandable. More specifically, the DDDmin metric is equal to the maximum of: zero; and 100% minus the sum of the %a2v messages that the vLP did not successfully receive and the %v2a messages that the aLP did not successfully receive, which can be expressed using the equation DDDmin metric=max(0, 100%-[(100%-a2v throughput)+(100%-v2a throughput)]. The corresponding VDD metric is equal to the a2v throughput minus the estimated DDDmin metric, which can be expressed using the equation VDD metric=a2v throughput-DDDmin. The corresponding DDI metric is equal to the v2a throughput minus the estimated DDDmin metric, which can be expressed using the equation DDI metric=v2a throughput-DDDmin. The corresponding VDI metric corresponds to the remainder of the period during which none of the DDD, VDD, or DDI operations are provided. In other words, the corresponding VDI metric is equal to 100% minus the sum of the DDDmin metric, the VDD metric, and the DDI metric, which can be expressed using the equation VDI metric=100%-sum(DDDmin, VDD metric, DDI metric).

[0137] Assume again, for example, that a2v throughput is equal to 90% (meaning that 90% of a2v messages sent by aLP are successfully received by vLP), and v2a throughput is equal to 80% (meaning that 80% of v2a messages sent by vLP are successfully received by aLP). Using the above equations, the DDDmin, VDD, DDI, and VDI metrics can be determined as follows. DDDmin metric = max(0, 100%-[(100%-a2v throughput) + (100%-v2a throughput)] = max(0, 100%-[100%-90%+100-80%]) = max(0, 100%-[10%+20%]) = max(0,70%) = 70%. VDD metric = a2v throughput - DDDmin metric = 80%-70% = 10%. DDI metric = v2a throughput - DDDmin = 90%-70% = 20%. VDI metric = 100%-sum(DDDmin, VDD metric, DDI metric) = 100%-sum(70%+10%+20%) = 100%-100% = 0%.

[0138] Fig.10 The diagram shown in helps visualize the time overlap options for successful a2v communication and successful v2a communication. The diagram uses a2v and v2a rows, where 10 squares together represent a total of 100% of the duration, and each of the 10 squares represents 10% of the duration. In each square, a value of 1 indicates successful i2i communication, and a value of 0 indicates unsuccessful i2i communication.

[0139] Reference again Fig. 6A , step 606 involves determining an AV synchronization metric within the time period (during which the aLP and vLP are configured to jointly provide DDD operation) based on the estimated DDD metric, the estimated VDD metric, the estimated DDI metric, the estimated VDI metric, and the event sequence information. The estimated DDD metric used at step 606 may be an estimated DDDmax metric, in which case corresponding estimates of the VDD, DDI, and DDI metrics are used. Alternatively, the estimated DDD metric used at step 606 may be an estimated DDDmin metric, in which case corresponding estimates of the VDD, DDI, and DDI metrics are used. A DDDmax metric (and its corresponding VDD, DDI, and DDI metrics) and a DDDmin metric (and its corresponding VDD, DDI, and DDI metrics) may also be determined, and each of these metrics may be used at step 606 to determine a corresponding AV synchronization metric, one of which specifies the maximum possible AV synchronization, and the other of which specifies the minimum possible AV synchronization, and they may collectively specify an AV synchronization range. As described above, the AV synchronization metric specifies an estimate of the frequency at which AV synchronization is achieved during the time period.

[0140] According to certain embodiments, the event sequence information (obtained at step 602 and used at step 606) includes AP-VP information, AP-VS information, AS-VP information, and AS-VS information. The AP-VP information specifies the frequency at which aLP provides atrial pacing (AP) and vLP provides ventricular pacing (VP) for the same cardiac cycle during the time period. The AP-VS information specifies the frequency at which aLP provides AP and vLP provides ventricular sensing (VS) for the same cardiac cycle during the time period. The AS-VP information specifies the frequency at which aLP provides atrial sensing (AS) and vLP provides VP for the same cardiac cycle during the time period. The AS-VS information specifies the frequency at which aLP provides AS and vLP provides VS for the same cardiac cycle during the time period. According to certain embodiments of the present technology, additional details of step 606 are provided below after the discussion of step 608a and in Figure 6B and Figure 6C A discussion of steps 608b and 608c is provided afterwards.

[0141] Reference again Fig. 6A , step 608a involves adjusting the implantation position of the aLP and / or vLP based on the AV synchronization metric. Fig. 6AThe method outlined may be performed, for example, by an external programmer (e.g., 109) during an implantation procedure and used to determine whether the implantation position of the aLP and / or vLP provides at least a threshold level of AV synchronization. For example, assume that the threshold level of AV synchronization is 60%. After the aLP (e.g., 102) and the vLP (e.g., 104) are implanted in the patient's heart (e.g., 101) using a catheter system, steps 602, 604, and 606 may be performed to determine an AV synchronization metric (at step 606), which may then be compared to the threshold level of AV synchronization. If the threshold level of AV synchronization is reached, it may be determined that the implantation position of the aLP and / or the implantation position of the vLP does not need to be adjusted. However, if the threshold level of AV synchronization is not reached, it may be determined that the implantation position of the aLP and / or the implantation position of the vLP needs to be adjusted, after which steps 602, 604, and 606 may be repeated to determine a new AV synchronization metric (at another instance of step 606).

[0142] Reference below Figure 6B and Figure 6C The description may be provided in place of (or in addition to) step 608a. In fact, Figure 6B and Figure 6C Steps 602, 604 and 606 in Fig. 6A The steps in the same numbering are the same, so when discussing Figure 6B and Figure 6C When , there is no need to repeat the details of steps 602, 604 and 606 (provided above). Figure 6B and Figure 6C Following the discussion of , further details of step 606 according to certain embodiments of the present technology are provided.

[0143] Reference now Figure 6B According to some embodiments, after determining the AV synchronization metric at step 606, step 608b involves adjusting at least one parameter used by the aLP to send additional a2v messages to the vLP, at least one parameter used by the vLP to receive additional a2v messages from the aLP, at least one parameter used by the vLP to send additional v2a messages to the aLP, and / or at least one parameter used by the aLP to receive additional v2a messages from the vLP based on the AV synchronization metric. Such parameters are examples of i2i communication parameters that can be programmed and adjusted, and when adjusted, may affect the resulting AV synchronization.

[0144] For example, steps 602, 604, and 606 may be performed while using default or programmed i2i communication parameters to determine whether AV synchronization using such i2i communication parameters provides at least a threshold level of AV synchronization. Assume again, for example, that the threshold level of AV synchronization is 60%. If the threshold level of AV synchronization is reached using the default or programmed i2i communication parameters, it may be determined that no i2i communication parameters need to be adjusted. However, if the threshold level of AV synchronization is not reached, it may be determined that one or more i2i communication parameters need to be adjusted, and more specifically, at least one parameter for the aLP to send additional a2v messages to the vLP, at least one parameter for the vLP to receive additional a2v messages from the aLP, at least one parameter for the vLP to send additional v2a messages to the aLP, and / or at least one parameter for the aLP to receive additional v2a messages from the vLP. The parameters for the aLP to send additional a2v messages to the vLP (which may be adjusted (e.g., increased)) include, but are not limited to, i2i communication pulse amplitudes and / or i2i communication pulse widths. Similarly, the parameters (which may be adjusted (e.g., increased)) used by the vLP to send additional v2a messages to the aLP include, but are not limited to, i2i communication pulse amplitude and / or i2i communication pulse width. The parameters (which may be adjusted) used by the vLP to receive additional a2v messages from the aLP include, but are not limited to, the gain of the receiving amplifier, the communication pulse sensing threshold, or more generally, the receiving communication sensitivity parameter. Similarly, the parameters (which may be adjusted) used by the aLP to receive additional v2a messages from the vLP include, but are not limited to, the gain of the receiving amplifier, the communication pulse sensing threshold, or more generally, the receiving communication sensitivity parameter.

[0145] As referenced above Figure 5 As explained, the sensed amplitude of an i2i communication pulse received by one LP (e.g., 104) from another LP (e.g., 102) can vary significantly based on the orientation of the LPs relative to each other. Thus, the sensed amplitude of the i2i communication pulse can vary significantly depending on the timing of sending the i2i communication pulse within the cardiac cycle and the posture of the patient when the pulse is sent. In accordance with certain embodiments of the present technology, the timing of sending v2a messages from the vLP to the aLP within the cardiac cycle and / or the timing of sending a2v messages from the aLP to the vLP within the cardiac cycle can be adjusted in an attempt to increase v2a throughput and / or a2v throughput for the purpose of attempting to improve AV synchronization.

[0146] Instead of or in addition to adjusting one or more i2i communication parameters to provide at least a threshold level of AV synchronization, various combinations of i2i communication parameters may be tested to optimize (eg, attempt to maximize) AV synchronization. According to some embodiments, performing reference Figure 6BThe method outlined is to determine what combination of i2i communication parameters (examples of which are described above) provides at least a threshold level of AV synchronization while minimizing energy consumption, or more generally, combinations of i2i communication parameters can be tested to determine which combination provides a good compromise between AV synchronization and power consumption. In other embodiments where it is desired to improve and preferably maximize device life, combinations of i2i communication parameters can be tested to determine which combination provides the lowest power consumption while still providing at least a threshold level of AV synchronization. Other variations are also possible and within the scope of the embodiments described herein.

[0147] Reference now Figure 6C According to some embodiments, after determining the AV synchronization metric at step 606, step 608c involves displaying the determined AV synchronization metric to the clinician on a display. Step 608c may be provided alone or in conjunction with one or more of steps 608a and 608b.

[0148] Once the AV synchronization metric is determined, a processor (or clinician) can make a determination based on the AV synchronization metric, such as whether one or both of the aLP and / or vLP, or a combination thereof, should be replaced, repositioned, or reprogrammed. For example, embodiments of the present technology described herein can be used to determine that acceptable AV synchronization is still achieved for certain patients even though i2i communication is poor in one direction, thereby indicating that replacement, repositioning, and / or reprogramming of the aLP and vLP is not necessary.

[0149] Alternatively or additionally, the AV synchronization metric determined at a separate instance of step 606, determined over an extended period of time, may be stored and used to generally track (also referred to as monitor) disease progression and / or device failure. Tracking disease progression based on the AV synchronization metric may be used to adjust (e.g., increase and / or change) a patient's medication, etc. Tracking of device failure may be used to determine when at least one of the aLP or vLP needs to be repositioned, replaced, or reprogrammed, but is not limited thereto. Other uses of the AV synchronization metric are possible and are within the scope of the embodiments described herein.

[0150] Step 606 (in Fig. 6A , Figure 6B and Figure 6C) for additional details. According to some embodiments, at step 606, the event sequence distribution is used in conjunction with the percentage of protection modes (DDI, VDD, and VDI) associated with DDDmin or DDDmax, and an estimated minimum %AV Sync is determined. The technique is the same for both DDDmin and DDDmax, but the values ​​are different, as previously shown, and the estimate obtained using DDDmin is lower than the estimate obtained using DDDmax. The example calculation shown below uses the value of DDDmin.

[0151] According to certain embodiments, determining the AV synchronization metric at step 606 involves determining a maximum %AV desynchronization during VDI operation, which depends on the event sequence distribution (e.g., AP-VS%, AP-VP%, and AS-VP%). When performing step 606, the estimated DDD, VDD, DDI, and VDI metrics (e.g., DDD%, VDD%, DDI%, and VDI%) have been determined at step 604 (based on the a2v throughput and v2a throughput obtained at step 602), and the event sequence information (e.g., AP-VP%, AP-VS%, AS-VP%, and AS-VS%) is known. However, when performing step 606, it is not known (also referred to as unknown) how the estimated DDD, VDD, DDI, and VDI metrics (e.g., DDD%, VDD%, DDI%, and VDI%) overlap with the event sequence information (e.g., AP-VP%, AP-VS%, AS-VP%, and AS-VS%). More specifically, it is unknown how often the AP-VP event sequence overlaps with each of DDD, VDD, DDI, and VDI; it is unknown how often the AP-VS event sequence overlaps with each of DDD, VDD, DDI, and VDI; it is unknown how often the AS-VP event sequence overlaps with each of DDD, VDD, DDI, and VDI; and it is unknown how often the AS-VS event sequence overlaps with each of DDD, VDD, DDI, and VDI. Therefore, according to certain embodiments, estimates of AV synchronization are determined for all of these various possible combinations of how the estimated DDD, VDD, DDI, and VDI metrics (e.g., DDD%, VDD%, DDI%, and VDI%) overlap with the event sequence information (e.g., AP-VP%, AP-VS%, AS-VP%, and AS-VS%), and the calculated AV synchronization that results in the worst-case scenario for AV synchronization is selected as the AV synchronization metric determined at step 606. Example details for implementing step 606 are described below. One of ordinary skill in the art reading the following description will appreciate that step 606 can be implemented in other similar ways that are also within the scope of the embodiments described herein.

[0152] First, the distributions of all relevant event sequences AP-VS / AP-VP / AS-VP are combined to obtain the minimum between them and VDI%, which results in the maximum desynchronization while providing VDI operation. Next, although the time overlap between the event sequence and the VDI operation period may be unknown, the following determinations can be provided for each of the six possible permutations of the event sequence order, and the permutation that results in the maximum %AV desynchronization is selected. The six possible permutations of the event sequence order are as follows: Sequence #1: AP-VS%, AP-VP%, AS-VP%; Sequence #2: AP-VS%, AS-VP%, AP-VP%; Sequence #3: AP-VP%, AS-VP%, AP-VS%; Sequence #4: AP-VP%, AP-VS%, AS-VP%; Sequence #5: AS-VP%, AP-VS%, AP-VP%; and Sequence #6: AS-VP%, AP-VP%, AP-VS%.

[0153] For a given sequence of events (e.g., sequence #1 above), the first event % (e.g., AP-VS%) is subtracted from the VDI% to obtain any remaining % in the first event. Vice versa, the VDI% is subtracted from the first event to obtain any remaining VDI%. For the remaining VDI%, the subtraction is provided with the second event, and vice versa to obtain any remaining % in the second event and the remaining portion of the VDI%. This is again provided for the third event to obtain any remaining % in the third event.

[0154] The algorithm continues with the remainder of each event percentage. The minimum between the sum of the event sequence AP-VS% and AP-VP% and VDD% is determined, resulting in the maximum AV desynchronization while providing VDD operation. Next, the minimum between AS-VP% and DDI% is determined, resulting in the maximum AV desynchronization while providing DDI operation. The AV desynchronization percentages while providing VDI, VDD, and DDI operations are then summed and subtracted from 100% to calculate the estimated minimum AV synchronization percentage for that particular event sequence order. Finally, after performing this calculation for all 6 possible event sequence permutations, the minimum of the 6 permutations is selected as the estimated minimum AV synchronization, which is an example of the AV synchronization metric determined at step 606. This example shows how combining event sequence information with a2v throughput and v2a throughput can result in an approximation of AV synchronization, which can then be used at steps 608a, 608b, and / or step 608c, and otherwise.

[0155] The following is an example of determination (e.g., calculation) of the following distribution using an operating mode and event sequence implemented by a dual-chamber LP system: DDD (minimum or maximum) = 60%; VDD = 15%; DDI = 5%; VDI = 20%; AP-VS = 35%; AP-VP = 40%; AS-VP = 25%; and AS-VS = 0%.

[0156] For the VDI protection operation mode, assuming VDI = 20%, the duration of the AV desynchronization (dys) of the event sequence AP-VS / AP-VP / AS-VP = 35% + 40% + 25% = 100%. VDI dys Maximum AV dyssynchrony % = min(20%,100%) = min(20,100) = 20%. Calculations are then provided based on the order of the sequence of events.

[0157] For event sequence order #1: AP-VS, AP-VP, AS-VP, remaining duration in AP-VS = max (AP-VS%-VDI dys Maximum AV dyssynchrony, %, 0) = max (35-20, 0) = 15. Remaining VDI duration after overlap with AP-VS = max (VDI dys Maximum AV dyssynchrony % - AP-VS%, 0) = max (20-35, 0) = 0%. Duration remaining in AP-VP = max (AP-VP% - VDI remaining after overlap with AP-VS, 0) = max (40-0, 0) = 40. Remaining VDI after overlap with AP-VP = max (Remaining VDI after overlap with AP-VS - AP-VP%, 0) = max (0-40, 0) = 0. Duration remaining in AS-VP = max (AS-VP% - VDI remaining after overlap with AP-VP, 0) = max (25-0, 0) = 25.

[0158] For the VDD protection operation mode, assuming VDD = 15%, the duration of the AV out-of-sync event sequence AP-VS / AP-VP (remaining) = remaining AP-VS (determined as above) + remaining AP-VP (determined as above) = 15% + 40% = 55%. VDD dys Maximum AV dyssynchrony % = min(VDD, duration of AV dyssynchrony event sequence in AP-VS / AP-VP) = min(15, 55) = 15%.

[0159] For DDI protection mode, assuming DDI = 5%, the duration of the AV out-of-sync event sequence in AS-VP = the remaining AS-VP (determined as above) = 25%. DDI dysMaximum AV dyssynchrony % = min(DDI, duration of AV dyssynchrony event sequence in AS-VP) = min(5, 25) = 5%.

[0160] Continuing with the above example calculation, total estimated minimum %AV sync = 100% - sum(VDI dys ,VDD dys ,DDI dys ) = 100% - sum(20,15,5) = 60%. Under these conditions (distribution of patterns and event sequences), the estimated minimum AV synchronization for the patient will be 60%. The actual AV synchronization may be higher. This example shows how combining event sequences and i2i can give an approximation of AV synchronization. This approximation can be presented to the customer to show the AV synchronization range customized for the patient.

[0161] Additional assumptions can be made about i2i communication loss (a2v and / or v2a communication loss) and overlap of event sequences where the simplified event sequence distribution is similar in time. This means that the overlap between protection modes and the need for event sequences do not have to be a worst case estimate to allow determination of the AV synchronization range.

[0162] In some embodiments, the ALP (e.g., 102) can be programmed to pace in the atrium given a need for atrial pacing (despite the simultaneous loss of A2V communications). This is referred to as a "bridge" cycle and is not included in the calculations provided in the above examples. The bridge cycle essentially maintains DDD mode during the loss of V2A I2I communications, and by default, it is currently only activated for the first cycle / beat of each V2A I2I communication loss (but it may potentially be extended to 2 or more cycles). The bridge cycle diagnostic can be considered to be added to the V2A throughput diagnostic. The calculation is provided by summing the count of V2A message reception and the bridge cycle count, and then dividing by the V2A message transmission. The example calculation provided above can be modified to take into account the bridge cycle, but instead use 75% of the V2A throughput. Then, if there is a bridge cycle with a 15% rate, the effective V2A throughput will be 90% (75% + 15%). The remaining calculations in the previous example will remain the same.

[0163] According to certain embodiments, at least one of the vLP or aLP maintains a histogram count of the number of sent v2a messages that the aLP did not successfully receive and / or the number of sent a2v messages that the vLP did not successfully receive, wherein the histogram is grouped by loss duration. The duration information is summed to obtain a total loss duration. For this total loss duration, the number of received i2i transmit messages (TX) is ~0. In order to allocate the number of TXs for this duration, the patient's average heart rate is determined using data from a heart rate histogram when the LP transmits a TX for each heartbeat. The calculation is divided into two periods, a loss period and a regular period. The loss period is the ratio of the number of i2i transmit messages (TX) without an RX message during the loss period to all TXs of the LP. The regular period is 1-loss period.

[0164] For the missing period, the distribution of the achieved operating modes is calculated by assuming 0% DDD and then calculating whether the i2i missing periods are overlapping or sequential. This results in two sets of VDD, DDI and VDI for sequential calculations (where VDI will be minimized) and overlapping calculations (where VDI will be maximized). The total i2i missing period ratio for the two sets of sequential mode calculations and overlapping mode calculations is used to create the corresponding regular period ratio. The i2i% performance for the regular period is recalculated by reducing the number of TXs sent during the missing period and then calculating RX / TX for each direction, where the TX in the denominator has a smaller amplitude during the regular period, while the RX count in the numerator remains virtually the same. The distribution of the mode is then calculated as above but using the new i2i performance values. The resulting mode distribution is then weighted by the regular period equal to 100% minus the missing period ratio. For each mode in the distribution, the missing period and the regular period are summed to provide the total % spent in that mode, which is then used to evaluate the impact on AV synchronization, as further described above.

[0165] Fig.13 A block diagram of one embodiment of an LP 1301 (e.g., 102 or 104) implanted into a patient as part of an implantable cardiac system according to some embodiments herein is shown. The LP 1301 can be implemented as a fully functional biventricular pacemaker equipped with both atrial and ventricular sensing and pacing circuits for four-chamber sensing and stimulation therapy (including both pacing and shock therapy). Optionally, the LP 1301 can provide fully functional cardiac resynchronization therapy. Alternatively, the LP 1301 can be implemented with a reduced set of functions and components.

[0166] LP 1301 has a housing 1300 to hold the electronic / computing components. The housing 1300 (which is often referred to as a "can," "shell," "encapsulation," or "housing electrode") can be programmably selected to be used as a return electrode for certain stimulation modes. The housing 1300 can also include a connector (not shown) having a plurality of terminals 1302, 1304, 1306, 1308, and 1310. The terminals can be connected to electrodes located at various locations on the housing 1300 or elsewhere in and around the heart. LP 1301 includes a programmable microcontroller 1320 that controls various operations of LP 1301, including cardiac monitoring and stimulation therapy. The microcontroller 1320 includes a microprocessor (or equivalent control circuitry), RAM and / or ROM memory, logic and timing circuits, state machine circuits, and I / O circuits.

[0167] LP 1301 further includes a pulse generator 1322 that generates stimulation pulses and communication pulses for delivery by one or more electrodes coupled thereto. Pulse generator 1322 is controlled by microcontroller 1320 via control signal 1324. Pulse generator 1322 can be coupled to select electrodes via electrode configuration switch 1326, which includes a plurality of switches for connecting the desired electrodes to the appropriate I / O circuits, thereby facilitating electrode programmability. Switch 1326 is controlled by control signal 1328 from microcontroller 1320.

[0168] exist Fig.13 In the embodiment of , a single pulse generator 1322 is shown. Alternatively, the IMD may include multiple pulse generators similar to pulse generator 1322, wherein each pulse generator is coupled to one or more electrodes and controlled by microcontroller 1320 to deliver selected stimulation pulses to the corresponding one or more electrodes.

[0169] The microcontroller 1320 is shown to include a timing control circuit 1332 for controlling the timing of stimulation pulses (e.g., pacing rate, atrial-ventricular (AV) delay, interatrial conduction (AA) delay, or interventricular conduction (VV) delay, etc.). The timing control circuit 1332 can also be used for the timing of refractory periods, blanking intervals, noise detection windows, evoked response windows, alarm intervals, marker channel timing, etc. The microcontroller 1320 also has an arrhythmia detector 1334 for detecting arrhythmic conditions. The microcontroller 1320 also has an AV synchronization detector 1336, which can be configured to determine an AV synchronization metric according to an embodiment of the present technology described herein. Although not shown, the microcontroller 1320 can also include other dedicated circuits and / or firmware / software components to assist in monitoring various conditions of the patient's heart and managing pacing therapy. The microcontroller can include a processor. The microcontroller and / or its processor can be used to perform the methods of the present technology described herein.

[0170] LP 1301 is also equipped with a communication modem (modulator / demodulator) 1340 to enable wireless communication with a remote slave pacing unit. Modem 1340 may include a Figure 1B One or more transmitters and two or more receivers discussed. In one embodiment, the modem 1340 can use low frequency or high frequency modulation. As an example, the modem 1340 can send i2i messages and other signals through conductive communication between a pair of electrodes. The modem 1340 can be implemented in hardware as part of the microcontroller 1320, or as software / firmware instructions programmed into and executed by the microcontroller 1320. Alternatively, the modem 1340 can reside separately from the microcontroller as an independent component.

[0171] LP 1301 includes a sensing circuit 1344 that is selectively coupled to one or more electrodes that perform sensing operations through switch 1326 to detect the presence of cardiac activity in the right chamber of the heart. Sensing circuit 1344 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 circuits to selectively sense cardiac signals of interest. Automatic gain control enables the unit to sense low amplitude signals characteristic of atrial fibrillation. Switch 1326 determines the sensing polarity of the cardiac signal by selectively closing the appropriate switch. In this way, the clinician can program the sensing polarity independently of the stimulation polarity.

[0172] The output of the sensing circuit 1344 is connected to the microcontroller 1320, which in turn triggers or inhibits the pulse generator 1322 in response to the presence or absence of cardiac activity. The sensing circuit 1344 receives control signals 1346 from the microcontroller 1320 for the purpose of controlling the gain, threshold, polarization charge removal circuit (not shown), and the timing of any blocking circuit (not shown) coupled to the input of the sensing circuit.

[0173] exist Fig.13 In the embodiment of FIG. 1 , a single sensing circuit 1344 is shown. Alternatively, the IMD may include multiple sensing circuits similar to sensing circuit 1344, wherein each sensing circuit is coupled to one or more electrodes and controlled by microcontroller 1320 to sense electrical activity detected at the corresponding one or more electrodes. Sensing circuit 1344 may operate in a unipolar sensing configuration or in a bipolar sensing configuration.

[0174] LP 1301 also includes an analog-to-digital (A / D) data acquisition system (DAS) 1350 coupled to one or more electrodes via switch 1326 to sample cardiac signals on any desired electrode pair. Data acquisition system 1350 is configured to acquire intracardiac electrogram signals, convert raw analog data to digital data, and store the digital data for later processing and / or telemetry transmission to an external system 1354 (e.g., a programmer, a local transceiver, or a diagnostic system analyzer). Data acquisition system 1350 is controlled by control signals 1356 from microcontroller 1320.

[0175] Microcontroller 1320 is coupled to memory 1360 via a suitable data / address bus. Programmable operating parameters used by microcontroller 1320 are stored in memory 1360 and are used to customize the operation of LP 1301 to suit the needs of a particular patient. Such operating parameters define, for example, pacing pulse amplitude, pulse duration, electrode polarity, rate, sensitivity, automatic features, arrhythmia detection criteria, and the amplitude, waveform, and vector of each shock pulse to be delivered to the patient's heart within each corresponding treatment level. Memory 1360 may also be used to store one or more of a2v throughput, v2a throughput, event sequence information, and / or one or more AV synchronization metrics.

[0176] The operating parameters of LP 1301 may be non-invasively programmed into memory 1360 via telemetry circuitry 1364, which is in telemetric communication with external system 1354 via communication link 1366. Telemetry circuitry 1364 allows intracardiac electrograms and status information related to the operation of LP 1301 (such as contained in microcontroller 1320 or memory 1360) to be sent to external system 1354 via communication link 1366.

[0177] LP 1301 may also include a magnet detection circuit (not shown) coupled to microcontroller 1320 to detect when a magnet is placed on the unit. The clinician may use the magnet to perform various test functions of LP 1301 and / or indicate to microcontroller 1320 that external system 1354 is in place to receive data or send data to microcontroller 1320 via telemetry circuit 1364.

[0178] LP 1301 may also include one or more physiological sensors 1370. Such sensors are often referred to as "rate-responsive" sensors because they are often used to adjust the pacing stimulation rate based on the patient's exercise state. However, physiological sensors 1370 may also be used to detect changes in cardiac output, changes in the physiological condition of the heart, or diurnal changes in activity (e.g., detecting sleep and wake states). Signals generated by physiological sensors 1370 are passed to microcontroller 1320 for analysis. Microcontroller 1320 responds by adjusting various pacing parameters (e.g., rate, AV delay, VV delay, etc.) for applying atrial and ventricular pacing pulses. Although shown as being included within LP 1301, physiological sensors 1370 may be external to LP 1301 but still implanted in or carried by the patient. Examples of physiological sensors may include, for example, sensors that sense respiratory rate, blood pH, ventricular gradient, activity, position / posture, minute ventilation (MV), and the like.

[0179] The battery 1372 provides operating power to all components in the LP 1301. The battery 1372 is capable of operating for long periods of time at low current consumption, and is capable of providing high current pulses (for capacitor charging) when a patient requires a shock pulse (e.g., in excess of 2A at voltages above 2V for a period of 10 seconds or longer). The battery 1372 also desirably has predictable discharge characteristics so that selective replacement time can be detected. As an example, the LP 1301 employs a lithium / silver vanadium oxide battery.

[0180] LP 1301 also includes impedance measurement circuitry 1374, which can be used for many things, including: lead impedance monitoring during acute and chronic phases for proper lead positioning or dislocation; detecting operable electrodes and automatically switching to operable electrode pairs if dislocation occurs; measuring respiration or minute ventilation; measuring thoracic impedance to determine shock thresholds; detecting when the device has been implanted; measuring stroke volume; and detecting the opening of heart valves; etc. Impedance measurement circuitry 1374 is coupled to switch 1326 so that any desired electrode can be used.

[0181] The process for chamber identification can also be applied to subcutaneous pacemakers, ICDs (with leads, etc.). For devices with one or more implanted leads, identification and / or confirmation of the chamber in which the lead is implanted may be useful in several relevant scenarios. For example, for a DR or CRT device, automatic identification and confirmation may mitigate the possibility of a clinician inadvertently placing a V lead into an A port of an implantable medical device, or vice versa. As another example, for an SR device, automatic identification of the implant chamber may enable the device and / or programmer to select and present an appropriate subset of operating modes (e.g., AAI or VVI), and enable the IPG to utilize an appropriate set of settings and algorithms (e.g., V- AutoCapture vs. ACap- Confirm, sensing sensitivity, etc.).

[0182] Fig.14 An example system is shown that can be used to determine, display, and otherwise use one or more AV synchronization metrics in accordance with embodiments of the present technology. Fig.14 14, the system is a distributed processing system 1400 that includes a server 1402 connected to a database 1404, a programmer 1406, a local monitoring device 1408, and a user workstation 1410 electrically connected to a network 1412. Any one or more of the processor-based components (e.g., workstation 1410, cellular phone 1414, local monitoring device 1416, server 1402, or programmer 1406, but not limited thereto) can perform the processes discussed herein.

[0183] The network 1412 can provide cloud-based services through the Internet, a Voice over IP (VoIP) gateway, a local plain old telephone service (POTS), a public switched telephone network (PSTN), a cellular phone-based network, etc. Alternatively, the communication system can be a local area network (LAN), a medical campus area network (CAN), a metropolitan area network (MAN), or a wide area network (WAM). The communication system is used to provide a network that facilitates the transmission / reception of data and other information between local and remote devices (relative to the patient). The server 1402 is a computer system that includes one or more processors and provides services to other computing devices on the network 1412. The server 1402 controls the transmission of information, such as physiological signal segments, bradycardia episode information, asystole episode information, arrhythmia episode information, markers, heart rate, and device settings. The server 1402 interfaces with the network 1412 to transmit information between the programmer 1406, the local monitoring devices 1408, 1416, the user workstation 1410, the cellular phone 1414, and the database 1404. Database 1404 stores information, such as physiological signal segments, arrhythmia episode information, arrhythmia statistics, diagnosis, heart rate, device settings, etc., for patient groups and separately for individual patients, individual physicians, individual clinics, individual medical networks, etc. Programmer 1406 can reside in the patient's home, hospital, or physician's office. Programmer 1406 can communicate wirelessly with IMD 1403 (e.g., aLP 102 and / or vLP 104) and utilize protocols such as Bluetooth, GSM, infrared wireless LAN, HIPERLAN, 3G, satellite, and circuit and packet data protocols, etc. Alternatively, a telemetry "stick" connection can be used to connect programmer 1406 to IMD 1403. Programmer 1406 can, for example, obtain ECG signal segments from surface electrodes on a person, obtain EGM signal segments from IMD 1403, and / or obtain arrhythmia episode information, arrhythmia statistics, diagnosis, markers, atrial heart rate, device settings from IMD 1403. Programmer 1406 interfaces with network 1412 via the Internet to upload information acquired from surface ECG unit 1420, or interfaces with network 1412 via IMD 1403 to upload to server 1402. IMD 1403 may be, for example, the one described above with reference to FIGS. Figure 7 IMD 610 is described, but not limited to.

[0184] The local monitoring device 1408 interfaces with the communication system to upload one or more physiological signal segments, motion data, arrhythmia episode information, arrhythmia statistics, diagnoses, markers, heart rate, sensitivity distribution parameter settings, and detection thresholds to the server 1402. In one embodiment, the surface ECG unit 1420 and the IMD 1403 have a two-way connection 1424 with the local RF monitoring device 1408 via a wireless connection. The local monitoring device 1408 is capable of acquiring surface ECG signal segments from one or more ECG leads 1422, as well as other information from the IMD 1403. In another aspect, the local monitoring device 1408 can download data and information discussed herein from the database 1404 to the IMD 1403. The pulse oximeter sensor that obtains the PPG segments can also be communicatively coupled to the local monitoring device 1408, 1416 or one of the programmer 1406 or the cellular telephone 1414.

[0185] Physicians or medical personnel can utilize user workstation 1410, cell phone 1414 and / or programmer 1406 to interface with network 1412 to download physiological signal segments, motion data and other information discussed herein from database 1404, from local monitoring devices 1408, 1416, from IMD 1403 or otherwise. Once downloaded, user workstation 1410 can process physiological signal segments and cause portions thereof to be displayed according to one or more of the above operations. According to embodiments of the present technology described herein, user workstation 1410, cell phone 1414 and / or programmer 1406 can be used to display portions of physiological signal segments to a clinician.

[0186] The user workstation 1410, cell phone 1414, and / or programmer 1406 may upload / push settings, IMD instructions, other information, and notifications to the cell phone 1414, local monitoring devices 1408, 1416, programmer 1406, server 1402, and / or IMD 1403. The user workstation 1410, cell phone 1414, and / or programmer 1406 may each include (or be communicatively coupled to) a display screen so that portions of physiological signal segments may be displayed on the display screen using embodiments of the present technology. The user workstation 1410, cell phone 1414, and / or programmer 1406 may each include (or be communicatively coupled to) a printer so that portions of physiological signal segments may be displayed on a printout (also referred to as a printed report) using embodiments of the present technology.

[0187] Fig.14 The system also includes one or more processors configured to execute specific executable instructions to perform the above steps, for example, referring to Fig. 6A , Figure 6B and / or Figure 6C .

[0188] Fig.15 A system-level diagram is shown indicating potential devices and networks utilizing the methods and systems herein. For example, IMD 1502 can be used to sense and store physiological signal segments. IMD 1502 can provide physiological signal segments to various local external devices, such as tablet device 1504, smart phone 1506, bedside monitoring device 1508, smart watch, etc. Devices 1504-1508 can include (or be communicatively coupled to) a display screen to enable display of physiological signal segments or portions thereof to a clinician, etc. The device can also include (or be communicatively coupled to) a printer that can print physiological signal segments or portions thereof for display and analysis by a clinician, etc.

[0189] IMD 1502 can transmit the physiological signal segments to devices 1504, 1506, and 1508 via various types of wireless communication links. IMD 1502 can utilize various communication protocols and be activated in various ways, such as conducted communication, Bluetooth, Bluetooth low energy, Wi-Fi, or other wireless protocols. Additionally or alternatively, when magnetic device 1510 is held next to the patient, the magnetic field from magnetic device 1510 can activate IMD 1502 to send the physiological signal segments and other information (e.g., arrhythmia data) to one or more of devices 1504-1508.

[0190] It should be understood that the subject matter described herein is not limited in its application to the details of the construction and arrangement of the components set forth in the description herein or shown in the drawings thereof. The subject matter described herein can have other embodiments and can be practiced or executed in various ways. In addition, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered restrictive. The use of "including", "comprising" or "having" and its variations herein is intended to cover the items listed thereafter and their equivalents and additional items. In addition, it should be noted that, unless otherwise stated, the term "based on" as used herein should be interpreted to mean at least partially based on, meaning that there may be one or more additional factors based on which decisions are made, etc. For example, if a decision is based on the result of a comparison, then in addition to being based on the result of the comparison, the decision may also be based on one or more other factors.

[0191] Embodiments of the present technology have been described above with the aid of functional building blocks that illustrate the execution of specified functions and their relationships. For ease of description, the boundaries of these functional building blocks are generally defined herein. Alternative boundaries may be defined, as long as the specified functions and their relationships are appropriately provided. Therefore, any such alternative boundaries are within the scope and spirit of the claimed invention. For example, the embodiments may be combined or separated. Fig. 6A , Figure 6B and Figure 6CFor another example, you can change Figure 1B , Fig.13 , Fig.14 and Fig.15 For example, step 602 may be divided into three sub-steps, and step 604 may be divided into four sub-steps.

[0192] 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) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the embodiments of the present technology without departing from the scope of the present technology. Although the dimensions and types of materials and coatings described herein are intended to define the parameters of the embodiments of the present technology, they are by no means restrictive, but exemplary embodiments. Many other embodiments will be apparent to those skilled in the art after reading the above description. Therefore, the scope of the embodiments of the present technology should be determined with reference to the appended claims and the full range of equivalents to which such claims are entitled. In the appended claims, the terms "including" and "wherein" are used as the plain English equivalents of the respective terms "including" and "wherein". In addition, in the appended claims, the terms "first", "second", and "third", etc. are used only as labels and are not intended to impose numerical requirements on their objects. In addition, the limitations of the appended claims are not written in a component plus function format and are not intended to be interpreted based on 35 USC §112 (f) unless and until such claim limitations expressly use the phrase "components for..." followed by a functional statement without further structure.

Claims

1. A system comprising or for use with an atrial leadless pacemaker aLP and a ventricular leadless pacemaker vLP, wherein the atrial leadless pacemaker aLP and the ventricular leadless pacemaker vLP are configured to communicate with each other, in, The aLP and the vLP are configured to jointly provide a DDD operation when an atrium-to-ventricle a2v message sent by the aLP is successfully received by the vLP and a ventricle-to-atrium v2a message sent by the vLP is successfully received by the aLP during a cardiac cycle, and wherein the aLP and the vLP are configured to jointly provide at least one of a VDD operation, a DDI operation, or a VDI operation during another cardiac cycle when at least one of an a2v message sent by the aLP is not successfully received by the vLP and / or a v2a message sent by the vLP is not successfully received by the aLP occurs at least some of the time, The system includes one or more processors configured to: obtaining a2v throughput, v2a throughput, and event sequence information during a time period when the aLP and the vLP are configured to jointly provide the DDD operation; determining an estimated DDD metric, an estimated VDD metric, an estimated DDI metric, and an estimated VDI metric for the time period based on the a2v throughput and the v2a throughput; and An atrial-ventricular AV synchronization metric is determined for the time period based on the estimated DDD metric, the estimated VDD metric, the estimated DDI metric, the estimated VDI metric, and the event sequence information, wherein the AV synchronization metric specifies an estimate of how often AV synchronization is achieved during the time period.

2. The system of claim 1, wherein: The system includes the aLP and the vLP, each of the aLP and the vLP including a respective processor of the one or more processors, and each of the aLP and the vLP including respective at least two electrodes; The aLP is configured to be implanted in or on an atrial heart chamber; The vLP is configured to be implanted in or on a ventricular chamber; The aLP is configured to send an a2v message to the vLP, and the vLP is configured to attempt to receive the a2v message from the aLP. The vLP is configured to send a v2a message to the aLP, and the aLP is configured to attempt to receive the v2a message from the vLP.

3. The system of claim 2, wherein: The processor of the vLP or the processor of the aLP comprises at least one of the one or more processors configured to determine the AV synchronization metric; and At least one of the processor of the vLP or the processor of the aLP is further configured to adjust one or more parameters of at least one of the aLP or the vLP based on the AV synchronization metric.

4. The system of claim 1, wherein: The system includes a non-implanted subsystem including at least one of the one or more processors, the at least one processor configured to determine the AV synchronization metric over the time period; as well as The at least one processor of the non-implanted subsystem is configured to adjust one or more parameters of at least one of the aLP or the vLP based on the AV synchronization metric.

5. A system according to any one of claims 1 to 4, wherein: The one or more processors configured to determine the AV synchronization metric within the time period are also configured to adjust, based on the AV synchronization metric, at least one parameter used by the aLP to send additional a2v messages to the vLP, at least one parameter used by the vLP to receive the additional a2v messages from the aLP, at least one parameter used by the vLP to send additional v2a messages to the aLP, and / or at least one parameter used by the aLP to receive the additional v2a messages from the vLP.

6. A system according to any one of claims 1 to 4, wherein: The one or more processors configured to determine the AV synchronization metric for the time period are further configured to cause the AV synchronization metric to be displayed.

7. A system according to any one of claims 1 to 4, wherein: The one or more processors configured to determine the AV synchronization metric within the time period are further configured to provide a notification that an implantation location of at least one of the aLP or the vLP should be modified.

8. A system according to any one of claims 1 to 4, wherein: the estimated DDD metric specifies an estimate of how often the aLP and the vLP jointly provide the DDD operation during the time period when the aLP and the vLP are configured to jointly provide the DDD operation; the estimated VDD metric specifies an estimate of how often the aLP and the vLP together provide the VDD operation during the time period; the estimated DDI metric specifies an estimate of the frequency with which the aLP and the vLP jointly provided the DDI operation during the time period; and The estimated VDI metric specifies an estimate of the frequency with which the aLP and the vLP jointly provided the VDI operation during the time period.

9. The system according to any one of claims 1 to 4, wherein: The event sequence information includes AP-VP information, AP-VS information, AS-VP information and AS-VS information; The AP-VP information specifies the frequency at which the aLP provides atrial pacing AP and the vLP provides ventricular pacing VP for the same cardiac cycle during the time period when the aLP and the vLP are configured to jointly provide the DDD operation; The AP-VS information specifies the frequency at which the aLP provides AP and the vLP provides ventricular sensing VS for the same cardiac cycle within the time period; The AS-VP information specifies the frequency at which the aLP provides atrial sensing AS and the vLP provides VP for the same cardiac cycle within the time period; and The AS-VS information specifies the frequency at which the aLP provides AS and the vLP provides VS for the same cardiac cycle within the time period.

10. The system according to any one of claims 1 to 4, wherein: The one or more processors are configured to: determining that the estimated DDD metric is equal to the minimum of the a2v throughput and the v2a throughput, or equal to the maximum of: zero, and 100% minus the sum of the percentage of a2v messages unsuccessfully received by the vLP and the percentage of v2a messages unsuccessfully received by the aLP; determining the estimated VDD metric to be equal to the a2v throughput minus the estimated DDD metric; Determining the estimated DDI metric equal to the v2a throughput minus the estimated DDD metric; as well as The estimated VDI metric is determined to be equal to 100% minus a sum of the estimated DDD metric, the estimated VDD metric, and the estimated DDI metric.

11. A method for use with a dual-chamber leadless pacemaker (LP) system comprising an atrial leadless pacemaker aLP and a ventricular leadless pacemaker vLP configured to communicate with each other, in, The aLP and the vLP are configured to jointly provide a DDD operation when an atrium-to-ventricle a2v message sent by the aLP is successfully received by the vLP and a ventricle-to-atrium v2a message sent by the vLP is successfully received by the aLP during a cardiac cycle, and wherein the aLP and the vLP are configured to jointly provide at least one of a VDD operation, a DDI operation, or a VDI operation during another cardiac cycle when at least one of an a2v message sent by the aLP is not successfully received by the vLP and / or a v2a message sent by the vLP is not successfully received by the aLP occurs at least some of the time, The method comprises: obtaining a2v throughput, v2a throughput, and event sequence information during a time period when the aLP and the vLP are configured to jointly provide DDD operations; determining an estimated DDD metric, an estimated VDD metric, an estimated DDI metric, and an estimated VDI metric for the time period based on the a2v throughput and the v2a throughput; and An atrial-ventricular AV synchronization metric is determined for the time period based on the estimated DDD metric, the estimated VDD metric, the estimated DDI metric, the estimated VDI metric, and the event sequence information, wherein the AV synchronization metric specifies an estimate of how often AV synchronization is achieved during the time period.

12. The method according to claim 11, further comprising: Based on the AV synchronization metric, adjust at least one parameter used by the aLP to send additional a2v messages to the vLP, at least one parameter used by the vLP to receive the additional a2v messages from the aLP, at least one parameter used by the vLP to send additional v2a messages to the aLP, and / or at least one parameter used by the aLP to receive the additional v2a messages from the vLP.

13. The method according to claim 11, further comprising: An implantation position of at least one of the aLP or the vLP is adjusted based on the AV synchronization metric.

14. The method according to claim 11, further comprising: The AV synchronization metric is displayed.

15. The method according to any one of claims 11 to 14, wherein: The aLP is configured to send an a2v message to the vLP; The vLP is configured to attempt to receive the a2v message from the aLP; The vLP is configured to send a v2a message to the aLP; The aLP is configured to attempt to receive the v2a message from the vLP; The a2v throughput specifies the frequency with which a2v messages sent by the aLP are successfully received by the vLP during the time period in which the aLP and the vLP are configured to jointly provide the DDD operation; The v2a throughput specifies the frequency with which v2a messages sent by the vLP are successfully received by the aLP during the time period; The sequence of events information specifies a frequency at which each of a plurality of different combinations of pacing and sensing occurs during the time period; the estimated DDD metric specifies an estimate of how often the aLP and the vLP jointly provide the DDD operation during the time period when the aLP and the vLP are configured to jointly provide the DDD operation; the estimated VDD metric specifies an estimate of how often the aLP and the vLP together provide the VDD operation during the time period; the estimated DDI metric specifies an estimate of the frequency with which the aLP and the vLP jointly provided the DDI operation during the time period; and The estimated VDI metric specifies an estimate of the frequency with which the aLP and the vLP jointly provided the VDI operation during the time period.

16. The method according to any one of claims 11 to 14, wherein: The event sequence information includes AP-VP information, AP-VS information, AS-VP information and AS-VS information; The AP-VP information specifies the frequency at which the aLP provides atrial pacing AP and the vLP provides ventricular pacing VP for the same cardiac cycle during the time period when the aLP and the vLP are configured to jointly provide the DDD operation; The AP-VS information specifies the frequency at which the aLP provides AP and the vLP provides ventricular sensing VS for the same cardiac cycle within the time period; The AS-VP information specifies the frequency at which the aLP provides atrial sensing AS and the vLP provides VP for the same cardiac cycle within the time period; and The AS-VS information specifies the frequency at which the aLP provides AS and the vLP provides VS for the same cardiac cycle within the time period.

17. The method according to any one of claims 11 to 14, wherein: Determining the estimated DDD metric, the estimated VDD metric, the estimated DDI metric, and the estimated VDI metric based on the a2v throughput and the v2a throughput includes: Determining that the estimated DDD metric is equal to a minimum value of the a2v throughput and the v2a throughput; determining the estimated VDD metric to be equal to the a2v throughput minus the estimated DDD metric; determining the estimated DDI metric to be equal to the v2a throughput minus the estimated DDD metric; and The estimated VDI metric is determined to be equal to 100% minus a sum of the estimated DDD metric, the estimated VDD metric, and the estimated DDI metric.

18. The method according to any one of claims 11 to 14, wherein: Determining the estimated DDD metric, the estimated VDD metric, the estimated DDI metric, and the estimated VDI metric based on the a2v throughput and the v2a throughput includes: determining the estimated DDD metric to be equal to the maximum of: zero, and 100% minus the sum of the percentage of a2v messages unsuccessfully received by the vLP and the percentage of v2a messages unsuccessfully received by the aLP; determining the estimated VDD metric to be equal to the a2v throughput minus the estimated DDD metric; determining the estimated DDI metric to be equal to the v2a throughput minus the estimated DDD metric; and The estimated VDI metric is determined to be equal to 100% minus a sum of the estimated DDD metric, the estimated VDD metric, and the estimated DDI metric.

19. The method according to any one of claims 11 to 14, wherein: The method is performed by a non-implanted system, which receives the a2v throughput and the v2a throughput from at least one of the aLP or the vLP, or receives the a2v throughput and the v2a throughput from another system, which has received the a2v throughput and the v2a throughput from at least one of the aLP or the vLP.

20. The method according to any one of claims 11 to 14, wherein: The method is performed by at least one of the aLP or the vLP.

21. A system comprising or for use with an atrial leadless pacemaker aLP and a ventricular leadless pacemaker vLP, wherein the atrial leadless pacemaker aLP and the ventricular leadless pacemaker vLP are configured to communicate with each other and jointly provide DDD operation during a cardiac cycle when an atrial-to-ventricular a2v message sent by the aLP is successfully received by the vLP and a ventricular-to-atrial v2a message sent by the vLP is successfully received by the aLP, and wherein, The aLP and the vLP are configured to jointly provide at least one of VDD, DDI, or VDI operations at least some of the time during another cardiac cycle when at least one of an a2v message sent by the aLP is not successfully received by the vLP and / or a v2a message sent by the vLP is not successfully received by the aLP, the system comprising one or more processors configured to: obtaining a2v throughput, v2a throughput, and event sequence information during a time period when the aLP and the vLP are configured to jointly provide DDD operations; determining, based on the a2v throughput and the v2a throughput, an estimate of a frequency at which the aLP and the vLP jointly provide each of DDD, VDD, DDI, and VVI operations during the time period; determining an atrial-ventricular AV synchronization metric for the time period based on the estimation; as well as Based on the AV synchronization metric, at least one parameter used by the aLP to communicate with the vLP and / or at least one parameter used by the vLP to communicate with the aLP is adjusted.

22. The system of claim 21, wherein: The system includes the aLP and the vLP, each of the aLP and the vLP including a corresponding processor and corresponding at least two electrodes; At least one of the processor of the vLP or the processor of the aLP comprises at least one of the one or more processors configured to determine the AV synchronization metric; and At least one of the processor of the vLP or the processor of the aLP is configured to adjust at least one parameter used by the aLP to communicate with the vLP and / or at least one parameter used by the vLP to communicate with the aLP.

23. The system of claim 21, wherein: The system includes a non-implanted subsystem, which includes at least one processor of the one or more processors, and the at least one processor is configured to determine the AV synchronization metric within the time period and adjust at least one parameter used by the aLP to communicate with the vLP and / or at least one parameter used by the vLP to communicate with the aLP based on the AV synchronization metric.

24. A method for use with a dual-chamber leadless pacemaker (LP) system, the dual-chamber leadless pacemaker (LP) system comprising an atrial leadless pacemaker aLP and a ventricular leadless pacemaker vLP, the atrial leadless pacemaker aLP and the ventricular leadless pacemaker vLP being configured to communicate with each other and to jointly provide DDD operation during a cardiac cycle when an atrial-to-ventricular a2v message sent by the aLP is successfully received by the vLP and a ventricular-to-atrial v2a message sent by the vLP is successfully received by the aLP, and wherein, The aLP and the vLP are configured to jointly provide at least one of VDD, DDI or VDI operations at least some of the time when at least one of an a2v message sent by the aLP is not successfully received by the vLP and / or a v2a message sent by the vLP is not successfully received by the aLP during another cardiac cycle, the method comprising: obtaining a2v throughput, v2a throughput, and event sequence information during a time period when the aLP and the vLP are configured to jointly provide DDD operations; determining, based on the a2v throughput and the v2a throughput, an estimate of a frequency at which the aLP and the vLP jointly provide each of DDD, VDD, DDI, and VVI operations during the time period; determining an atrioventricular (AV) synchronization metric for the time period based on the estimation; and Based on the AV synchronization metric, at least one parameter used by the aLP to communicate with the vLP and / or at least one parameter used by the vLP to communicate with the aLP is adjusted.

25. The method according to claim 24, wherein: The method is performed by a non-implanted system, which receives the a2v throughput and the v2a throughput from at least one of the aLP or the vLP, or receives the a2v throughput and the v2a throughput from another system, which has received the a2v throughput and the v2a throughput from at least one of the aLP or the vLP.

26. The method according to claim 24, wherein: The method is performed by at least one of the aLP or the vLP.

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