Cardiac pacing devices

Abstract

The invention relates to a cardiac pacing device (3) comprising a first leadless pacing device (1) and a second leadless pacing device (2), where the second leadless pacing device (2) is configured to operate in a standby state (20) or an active state (21). During operation, the cardiac pacing device (1) performs the following steps: a) determining whether conditions (101, 102, 103) for transitioning the second leadless pacing device (2) from the standby state (20) to the active state (21) are met, where the conditions (101, 102, 103) are: i) N consecutive stimulation pulses have been delivered by the second stimulation unit, where N is an integer in the range of 2 to 10; ii) a second detection unit detects that a stimulation pulse delivered by the first stimulation unit has been delivered within a time period between 0.5 and 72 ms; and iii) M consecutive non-captured stimulation pulses delivered by the first stimulation unit are detected by the second detection unit, where M is an integer in the range of 2 to 10; and b) transitioning the second leadless pacing device (2) from a standby state (20) to an operating state (21) if conditions (101, 102, 103) are met.

Description

[Technical field]

[0001] The invention relates to a cardiac pacing device according to the preamble of claim 1, to a method for controlling a cardiac pacing device according to the preamble of claim 9 and to a computer program product according to the preamble of claim 10.

[0002] In recent years, leadless pacemakers have been attracting increasing attention. In contrast to pacemakers implanted subcutaneously with leads extending transvenously into the heart, leadless pacemakers are pacemaker devices that are implanted into the heart without the use of leads. Leadless pacemakers typically have a capsule shape that is implanted into cardiac tissue, for example, in the right atrium and / or right ventricle. Such leadless pacemakers have the inherent advantage of not using leads, which can reduce patient risks associated with transvenously accessing the heart with leads, such as pneumothorax, pacing system infection, and lead failure (breakage or insulation failure).

[0003] Leadless pacemakers may be specifically designed for implantation in the right ventricle and / or right atrium, where they are preferably positioned within or above the septal or apical regions of the right ventricle during implantation. Leadless pacemakers are averse to using radio frequency (RF) telemetry for remote monitoring based on their extremely low power design, but may utilize an inductive communication interface for patient-triggered remote interrogation when circumstances permit.

[0004] If a leadless pacemaker is implanted for an extended period of time, it can no longer be periodically removed. Rather, when it reaches the end of its lifetime (also referred to as "end of lifetime" EOL or "end of use" EOS), the leadless pacemaker remains in the patient's heart. Further cardiac stimulation is performed by another pacemaker (leadless-based or lead-based) implanted in the same heart.

[0005] Over time, multiple leadless pacemakers may be implanted in a patient's heart. The procedure of exchanging a stimulator or stimulation unit from an old leadless pacemaker to a new leadless pacemaker is also referred to as a box exchange procedure. A safety buffer time for such a box exchange is essential to avoid any period during which pacing is not possible. For this reason, it is necessary to implant a successor (new) leadless pacemaker before the use of the previous (old) leadless pacemaker is terminated. Thus, each successor leadless pacemaker is implanted shortly before or just after the selective exchange time indicator (ERI) of the previous leadless pacemaker is reached. Thus, the implantation of the successor leadless pacemaker occurs when the battery of the previous leadless pacemaker is not yet completely discharged. As a result, part of the battery capacity of the previous (old) leadless pacemaker is wasted with the deactivation of the previous (old) leadless pacemaker and the activation of the successor (new) leadless pacemaker.

[0006] WO 2015 / 095818 describes an approach to perform a box exchange procedure while improving power usage. For this purpose a new leadless pacemaker is embedded but is initially kept dormant while the old leadless pacemaker is still active. At a later stage the old leadless pacemaker sends a signal to the new leadless pacemaker to activate it. In this way the cumulative lifetime of the old and new leadless pacemakers is higher than when applying a standard box exchange procedure. However, the procedure described in WO 2015 / 095818 requires compatibility of the old and new leadless pacemakers to allow the activation of the new leadless pacemaker.

[0007] An object of the present invention is to provide a system and method for a leadless pacemaker box exchange procedure that is applicable in the case of incompatible leadless pacemakers while maximizing the use of power from the old leadless pacemaker and the new leadless pacemaker and maintaining high patient safety.

[0008] The above object is achieved by a cardiac pacing device having the features of claim 1. The cardiac pacing device includes a first leadless pacing device and a second leadless pacing device.

[0009] The first leadless pacing device includes a first processor, a first memory unit, a first stimulation unit, and a first sensing unit, the first stimulation unit configured to stimulate a human or animal heart, and the first sensing unit configured to sense electrical signals of the same heart.

[0010] The second leadless pacing device comprises a second processor, a second memory unit, a second stimulation unit, and a second sensing unit. The second stimulation unit is configured to stimulate the same heart as the first stimulation unit. Similarly, the second sensing unit is configured to sense the same cardiac electrical signals as the first sensing unit. Thus, both the first leadless pacing device and the second leadless pacing device can be used to sense and pace the same heart of a human or animal patient.

[0011] The second leadless pacing device is further configured to operate in one of at least two functional states: a first functional state is a standby state (also referred to as a dormant state) and a second functional state is an operating state (also referred to as a constant state).

[0012] As an alternative to leadless pacing devices, other pacing devices may be used, such as lead-based pacing devices or pacemakers that are implanted subcutaneously with leads extending intravenously into the heart.

[0013] In one aspect of the invention, the second memory unit includes a second computer readable program which, when executed on the second processor, causes the second processor to perform each of the steps described below.

[0014] The first step determines whether a condition is met for transitioning the second leadless pacing device from a standby state to an active state, the condition being selected from one of the conditions described below.

[0015] The first condition is fulfilled if N successive stimulation pulses have been delivered by the second stimulation unit, where N is an integer in the range 2 to 50, in particular 2 to 45, in particular 2 to 40, in particular 2 to 35, in particular 2 to 30, in particular 2 to 25, in particular 2 to 20, in particular 2 to 15, in particular 2 to 10, in particular 2 to 8, in particular 2 to 5. If the second stimulation unit needs to deliver such an amount of successive stimulation pulses, this is a direct indication that the first leadless pacing device (i.e. the old leadless pacing device that is being replaced by the second (new) leadless pacing device) is no longer stimulating the patient's heart due to discharging of its battery. At the same time, the patient needs stimulation, for which the second leadless pacing device has already delivered multiple successive stimulation pulses in its standby state.

[0016] The second condition is met if the second detection unit fails to detect any stimulation pulses delivered by the first stimulation unit for a predetermined time period ranging from 0.5 h to 72 h, particularly 1 h to 60 h, particularly 1 h to 48 h. Failure to detect any stimulation pulses from the first leadless pacing device for such a long time period is a clear indication that the battery of the first leadless pacing device is fully discharged and, as a result, the first leadless pacing device can no longer stimulate the patient's heart or perform any automated tests (such as capture threshold tests). At the same time, the patient has a sufficiently active intrinsic cardiac rhythm that backup stimulation by the second leadless pacing device is not currently required.

[0017] The third condition is met if the second detection unit detects M consecutive non-captured stimulation pulses delivered by the first stimulation unit, where M is an integer in the range 2 to 50, particularly 2 to 40, particularly 2 to 30, particularly 2 to 20, particularly 2 to 10, particularly 2 to 8, particularly 2 to 5. If such a non-captured stimulation pulse is detected, this is a clear indication that the battery capacity of the first leadless pacing device is too low to deliver a stimulation pulse above the stimulation threshold. However, a stimulation pulse below the stimulation threshold has resulted in a non-captured event (i.e., no physiological response to the applied stimulation pulse). Since the non-captured stimulation pulse does not result in stimulation to the patient's heart, further cardiac stimulation needs to be performed by the second leadless pacing device.

[0018] In a second step performed by the second processor, the second leadless pacing device is transitioned from a standby state to an active state if at least one of the above conditions is satisfied, such that the second leadless pacing device is not only able to provide backup stimulation to the patient but is also fully functional within the patient's heart. By transitioning the second leadless pacing device to the active state, the second leadless pacing device takes over all relevant stimulation activities previously performed by the first leadless pacing device. Transitioning the second leadless pacing device to the active state thus constitutes the final step of the overall box replacement procedure in which pacing functionality is transferred from the first to the second leadless pacing device.

[0019] Full operation of the second leadless pacing device is not required as long as the first leadless pacing device is functioning properly. Rather, by maintaining the second leadless pacing device in a standby state as long as possible, battery capacity of the second leadless pacing device is conserved and the cumulative lifetime of the first and second leadless pacing devices is increased. This allows implantation of a third leadless pacing device, and any subsequent leadless pacing devices, at a later time than would be possible if the first leadless pacing device were to be deactivated after implantation of a fully operational second leadless pacing device. At the same time, patient safety is particularly enhanced by the second leadless pacing device being able to provide backup stimulation in its backup state if the first leadless pacing device is no longer capable of providing adequate cardiac stimulation.

[0020] The first and second leadless pacing devices can be compatible devices capable of communicating with each other, but this is not a prerequisite. Rather, according to one embodiment, the first and second leadless pacing devices are incompatible devices. The cardiac pacing device claimed herein is fully functional in such an embodiment because the second leadless pacing device does not depend on a specific set of data or information provided by the first leadless pacing device to transition from a standby state to an active state. Rather, the second leadless pacing device detects a malfunction of the first leadless pacing device (especially caused by a dead or discharged battery in the first leadless pacing device) and is automatically activated at this point. Because compatibility between the first and second leadless pacing devices is not required, the cardiac pacing device claimed herein is universally applicable regardless of the type and manufacturer of the first leadless pacing device.

[0021] According to one embodiment, the second leadless pacing device is configured to enable backup stimulation of the heart at a backup stimulation rate lower than the normal or lowest stimulation rate applied by the first stimulation unit of the first leadless pacing device, even during optional testing or hysteresis, by operation of the second leadless pacing device in a standby state. This prevents any conflicts between the first and second leadless pacing devices that may occur while the first leadless pacing device is still active in the absence of the invention. By way of example, backup stimulation is available in VVI mode (ventricular pacing, ventricular sensing, and pacing inhibition if intrinsic cardiac activity is detected) at rates in the range of 30 bpm to 60 bpm, particularly 30 ppm to 55 bpm, particularly 35 ppm to 50 ppm. In contrast, the normal or lowest stimulation rate applied by the first stimulation unit of the first cardiac leadless pacing device, even during optional testing or hysteresis application, is higher than the applied backup stimulation rate, and thus as long as the first leadless pacing device is active, its stimulation dominates the patient's cardiac rhythm and does not result in activation of the second leadless pacing device because the stimulation rate applied by the first leadless pacing device is higher than its backup stimulation rate.

[0022] According to one embodiment, the second leadless pacing device is designed such that at least a part of the second leadless pacing device, in particular all of its electrical consuming elements or electrical consuming actions, are deactivated when the second leadless pacing device operates in a standby state. In this context, only electrical consuming elements or electrical consuming actions of the second leadless pacing device are deactivated that are not required for delivery of stimulation pulses by the second stimulation unit and / or for monitoring of cardiac rate, thereby detecting the need for stimulation or monitoring triggering. Energy consumption of the second leadless pacing device is minimized or significantly reduced by such deactivation of selected or not all electrical consuming elements or electrical consuming actions that are completely necessary. This extends the lifetime of the second leadless pacing device and thus the entire cardiac pacing device.

[0023] In one embodiment, electrical consuming elements or activities of the second leadless pacing device not required for delivery of a stimulation pulse by the second stimulation unit are one or more of a sensor different from or other than the second sensing unit (necessary for determining whether stimulation by the second stimulation unit should occur), a statistical calculator related to sensed electrical signals and / or delivered pacing pulses, and a measurement unit, such as an automatic capture threshold test measurement unit or an impedance measurement unit.

[0024] Additionally or alternatively, electrical consuming elements or activities of the second leadless pacing device not required for delivery of stimulation pulses by the second stimulation unit can be selected from the group consisting of sensors such as statistical calculations related to sensed electrical signals, automatic capture threshold test measurements, impedance measurements, and other measurements, generally other than the second sensing unit and / or pacing pulse delivery unit and / or stimulation unit.

[0025] To ensure proper functionality and proper documentation of that functionality, all of these elements or operations are required in the operating state of the second leadless pacing device, but are not required in the standby mode of the second leadless pacing device due to the fact that the equivalent elements and operations are activated or performed by the active first leadless pacing device during the standby phase of the second leadless pacing device.

[0026] According to one embodiment, the second leadless pacing device is transitioned from the standby state to the active state immediately, i.e., on a beat-to-beat basis. Such an immediate transition means that all functions and functional parts of the active state are activated from one cardiac beat to the next. According to another embodiment, the transition of the second leadless pacing device from the standby state to the active state is performed stepwise, i.e., over multiple cardiac cycles, rather than directly from one cardiac beat to the next. Such a stepwise transition from the standby state to the active state is believed to be more physiological than a beat-to-beat transition.

[0027] According to one embodiment, the second computer readable program causes the second processor to transmit information to the first leadless pacing device upon transition from the standby state to an active state indicating that the second leadless pacing device is operating in an active state, where the information can be provided from the second leadless pacing device to the first leadless pacing device via interbody communication or via a specific predetermined specific stimulation sequence. Such back-channel communication between the second and first leadless pacing devices requires compatibility of the first and second leadless pacing devices to enable the first leadless pacing device to understand information (or instructions) provided by the second leadless pacing device. Thus, this embodiment is generally combined with embodiments in which the first and second leadless pacing devices are compatible for data or information exchange.

[0028] According to one embodiment, the first leadless pacing device is compatible with the second leadless pacing device, i.e., the first leadless pacing device understands information transmitted by the second leadless pacing device, but the second leadless pacing device does not necessarily understand information transmitted by the first leadless pacing device. In other words, the embodiment requires unidirectional compatibility, but not necessarily bidirectional compatibility between the first and second leadless pacing devices.

[0029] In one embodiment, the first memory unit contains a first computer readable program that, when executed on the first processor, causes the first processor to transition the first leadless pacing device from an active state to a standby state in response to receiving information indicating the second leadless pacing device is operating in an active state. A back-channel between the second and first leadless pacing devices can then be used to actively change the functional state of the first leadless pacing device. Such active changing of functional state can also be useful when the first leadless pacing device has a too low battery capacity to adequately stimulate the patient's heart because the first leadless pacing device can perform special tasks in its standby state that can help conserve energy for the second leadless pacing device. In this case, the overall lifetime of the cardiac pacing devices is further extended and the implantation time of a third or further successor leadless pacing device is shifted further into the future.

[0030] In one embodiment, the first leadless pacing device is designed such that operation of the first leadless pacing device in a standby state enables the first leadless pacing device to perform statistical calculations related to sensed electrical signals without requiring the second leadless pacing device to contribute computing power or power capacity required to perform such calculations, and instead further utilizes the first leadless pacing device's battery, even if it is depleted and unable to adequately stimulate the patient's heart.

[0031] According to one embodiment, the first memory unit contains a first computer readable program which, when executed on the first processor, causes the first processor to transition the first leadless pacing device from an active state to an inactive state in response to receiving information indicating that the second leadless pacing device is operating in an active state. Unlike the above-described embodiments, in this embodiment the first leadless pacing device is not transitioned to a standby state but rather to an inactive (off) state in which it is unable to perform any further tasks. This is useful for enhancing cardiac pacing device safety by preventing the first leadless pacing device from being unable to perform other tasks (as provided in the standby state of the first leadless pacing device) due to low battery capacity. In any case, the first leadless pacing device will only be transitioned to the inactive state if its battery capacity is too low to further stimulate the patient's heart. In this case, the battery of the first leadless pacing device is considered to be completely depleted.

[0032] In one embodiment, the cardiac pacing device is a pacing device having three or more leadless pacing devices, which can include, by way of example, a first atrial leadless pacing device, a second atrial leadless pacing device, a first ventricular leadless pacing device, and a second ventricular leadless pacing device. In this case, the second atrial leadless pacing device is transitioned from its standby state to an active state only if one of the conditions described above for the first atrial leadless pacing device (first condition, second condition, and / or third condition) is met. Similarly, the second ventricular leadless pacing device is transitioned from its standby state to an active state only if one of the conditions described above for the first ventricular leadless pacing device is met.

[0033] When more than two leadless pacing devices are present in a cardiac pacing system, each leadless pacing device can be replaced with a new leadless pacing device at different times, such that the cardiac pacing system can contain a variable number of leadless pacing devices over time.

[0034] In one embodiment, the two functional states, standby and operational, are represented by programming of the second leadless pacing device that is transferred from the programmer to the second leadless pacing device in the form of an inseparable composite command. If the command is correctly received by the second leadless pacing device, the second leadless pacing device provides an acknowledgment of its receipt. If the composite command is not correctly received by the second leadless pacing device, it must be transferred again or suitably repeated. This programming of the second leadless pacing device ensures that the standby state is not the only functional state applicable by the second leadless pacing device and that the second leadless pacing device is always operable in the operational state, further enhancing the reliability and safety of the overall cardiac pacing system.

[0035] In one aspect, the invention relates to a method of controlling a cardiac pacing device in accordance with the above description, the method comprising the steps described below.

[0036] The first step determines whether a condition is met for transitioning the second leadless pacing device from a standby state to an active state, the condition being selected from one of the conditions described below.

[0037] The first condition is fulfilled if N successive stimulation pulses are emitted by the second stimulation unit, where N is an integer in the range 2 to 50, in particular 2 to 45, in particular 2 to 40, in particular 2 to 35, in particular 2 to 30, in particular 2 to 25, in particular 2 to 20, in particular 2 to 15, in particular 2 to 10, in particular 2 to 8, in particular 2 to 5.

[0038] The second condition is met if the second detection unit fails to detect stimulation pulses emitted from the first stimulation unit over a predetermined period in the range of 0.5 hours to 72 hours, in particular 1 hour to 60 hours, in particular 1 hour to 48 hours, but optionally at the same time detects the patient's existing intrinsic rhythm.

[0039] The third condition is met if the second detection unit detects M consecutive non-captured stimulation pulses emitted by the first stimulation unit, where M is an integer in the range 2 to 50, in particular 2 to 45, in particular 2 to 40, in particular 2 to 35, in particular 2 to 30, in particular 2 to 20, in particular 2 to 15, in particular 2 to 10, in particular 2 to 8, in particular 2 to 5.

[0040] In a second step, the second leadless pacing device is transitioned from a standby state to an active state if at least one of the above conditions is met.

[0041] In one aspect, the present invention relates to a computer program product comprising computer readable code which, when executed on a processor, causes the processor to perform the steps described below.

[0042] The first step determines whether a condition is met for transitioning the second leadless pacing device from a standby state to an active state, the condition being selected from one of the conditions described below.

[0043] The first condition is fulfilled if N successive stimulation pulses are emitted by the second stimulation unit, where N is an integer in the range 2 to 50, in particular 2 to 45, in particular 2 to 40, in particular 2 to 35, in particular 2 to 30, in particular 2 to 25, in particular 2 to 20, in particular 2 to 15, in particular 2 to 10, in particular 2 to 8, in particular 2 to 5.

[0044] The second condition is met if the second detection unit of the second leadless pacing device fails to detect stimulation pulses delivered by the first stimulation unit for a predetermined time period in a range of 0.5 hours to 72 hours, particularly 1 hour to 60 hours, and particularly 1 hour to 48 hours, but optionally simultaneously detects the patient's existing intrinsic rhythm.

[0045] A third condition is met if M consecutive non-captured stimulation pulses delivered by a first stimulation unit of the first leadless pacing device are detected by the second detection unit, where M is an integer in the range 2 to 50, particularly 2 to 45, particularly 2 to 40, particularly 2 to 35, particularly 2 to 30, particularly 2 to 20, particularly 2 to 10, particularly 2 to 15, particularly 2 to 8, particularly 2 to 5.

[0046] In a second phase, the second leadless pacing device is transitioned from a standby state to an active state if at least one of the above conditions is met.

[0047] In one aspect, the invention relates to a medical method for stimulating a patient's heart with a cardiac pacing device according to the above description, said method comprising the steps as described below.

[0048] The first step determines whether a condition is met for transitioning the second leadless pacing device from a standby state to an active state, the condition being selected from one of the conditions described below.

[0049] The first condition is fulfilled if N successive stimulation pulses are emitted by the second stimulation unit, where N is an integer in the range 2 to 50, in particular 2 to 45, in particular 2 to 40, in particular 2 to 35, in particular 2 to 30, in particular 2 to 25, in particular 2 to 20, in particular 2 to 15, in particular 2 to 10, in particular 2 to 8, in particular 2 to 5.

[0050] The second condition is met if the second detection unit fails to detect stimulation pulses emitted from the first stimulation unit over a predetermined period in the range of 0.5 hours to 72 hours, in particular 1 hour to 60 hours, in particular 1 hour to 48 hours, but optionally at the same time detects the patient's existing intrinsic rhythm.

[0051] The third condition is met if the second detection unit detects M consecutive non-captured stimulation pulses emitted by the first stimulation unit, where M is an integer in the range 2 to 50, in particular 2 to 45, in particular 2 to 40, in particular 2 to 35, in particular 2 to 30, in particular 2 to 20, in particular 2 to 15, in particular 2 to 10, in particular 2 to 8, in particular 2 to 5.

[0052] In a second phase, the second leadless pacing device is transitioned from a standby state to an active state if at least one of the above conditions is met.

[0053] Finally, at least one stimulation pulse is delivered to the patient's heart by the second stimulation unit and / or by a further stimulation unit or pacing device.

[0054] In one embodiment, at least one of the stimulation unit and pacing device may be a multi-chamber unit or device.

[0055] Additionally, additional (external) triggers for stimulation by the pacing device and / or stimulation unit are possible, but such additional triggers act only in addition to the triggers mentioned above (triggers can be for all devices or units triggering stimulation). Two examples of such additional triggers are a) triggering after expiration of a preprogrammed timer in the new (preferably first) leadless pacing device to ensure the latest possible and / or fixed time point for activating the new leadless pacing device, and b) sending an external command to the new leadless pacing device, for example, by applying or placing a magnet in the vicinity of the pacing device or by sending a command using an external device (remote auxiliary device or any external device capable of doing the above).

[0056] All embodiments of the cardiac pacing device may be combined in any desired manner and transferred, individually or in any combination, into the described methods and computer program products. Similarly, all embodiments of the described methods may be combined in any desired manner and transferred, individually or in any combination, into the cardiac pacing device, the corresponding other methods and computer program products. Furthermore, all embodiments described with respect to computer program products may also be combined in any desired manner and transferred, individually or in any combination, into the cardiac pacing device or any of the described methods.

[0057] Further details of aspects of the invention are explained below with reference to exemplary embodiments and figures. [Brief description of the drawings]

[0058] [Figure 1] FIG. 1 illustrates a schematic diagram of a timeline of the lifetime of two leadless pacing devices in a cardiac pacing device.

[0059] 1 shows a schematic time line illustrating the lifetime of a first leadless pacemaker 1 functioning as a first leadless pacing device and the lifetime of a second leadless pacemaker 2 functioning as a second leadless pacing device. The first leadless pacemaker 1 and the second leadless pacemaker 2 form a cardiac pacing device 3.

[0060] A first leadless pacemaker 1 is implanted in the heart of a human or animal patient at a first implantation time 4. Shortly after an optional exchange time indicator (ERI) 5 is reached, a second leadless pacemaker 2 is implanted in the same patient's heart at a second implantation time 6. Measurements and tests required for proper operation of the second leadless pacemaker 2 are performed at the time of implantation or shortly thereafter. The second leadless pacemaker 2 has two functional modes: a standby program 20 that functions as a standby state (or dormant or quiescent state), and a home program 21 that functions as an operating state.

[0061] The first leadless pacemaker 1 is normally active in a home program 11, while the second leadless pacemaker 2 is already installed and uses a standby program 20 that allows for backup pacing for safety reasons, where all other tasks and elements that may consume electricity are deactivated. By way of example, the second leadless pacemaker 2 does not calculate any statistics in its standby program 20.

[0062] At a generally unknown time 7, the first leadless pacemaker 1 stops pacing without an external trigger due to battery depletion. The second leadless pacemaker 2 recognizes the cessation of pacing by determining 30 whether at least one of a first condition 101, a second condition 102 and a third condition 103 is satisfied. If pacing has stopped, the second leadless pacemaker 2 automatically executes step 40 of transitioning its functional state from a standby program 20 to a constant program 21. While the constant program 21 is applied, the second leadless pacemaker can execute any stimulation and auxiliary tasks that are regularly executed during standard stimulation. In their execution, the leadless pacemaker 2 takes over the full stimulation function from the first leadless pacemaker 1 at a generally unknown time 7 if the first condition 101, the second condition 102 and / or the third condition 103 are satisfied.

[0063] The first condition 101 is met if N consecutive stimulation pulses are emitted from the second stimulation unit, where N is between 2 and 50 or between 2 and 10. The second condition 102 is met if the second detection unit fails to detect any stimulation pulses emitted from the first stimulation unit over a predefined period of time, which is set to 24 hours in the embodiment shown in Fig. 1. The third condition 103 is met if the second detection unit detects M consecutive non-captured stimulation pulses emitted from the first stimulation unit, where M is between 2 and 50 or between 2 and 10.

[0064] These very special conditions 101, 102, 103 ensure that at a generally unknown time 7 when the first leadless pacemaker 1 can no longer perform an appropriate stimulation to the heart in which it is implanted, the second leadless pacemaker 2 automatically changes its operation by switching from a standby program 20 to a home program 21. This automatic change does not require the second leadless pacemaker 2 to receive an external trigger. The setup of the cardiac pacing device 3 therefore ensures the maximum possible lifetime of the first and second leadless pacemaker 1, 2, which allows the implantation of a third leadless pacemaker to be postponed to a great extent. The setup does not require compatibility between the first and second leadless pacemaker 1, 2. Furthermore, the setup prevents the risk that any command sent from the first leadless pacemaker 1 to the second leadless pacemaker 2 will not be received by the second leadless pacemaker 2 or will be misinterpreted by the second leadless pacemaker 2. Rather, full activation of the second leadless pacemaker 2 is automatically triggered by deactivation of the first leadless pacemaker 1 at a generally unknown time 7 .

Claims

1. A cardiac pacing device (3) comprising a first leadless pacing device (1) and a second leadless pacing device (2), the first leadless pacing device (1) comprising a first processor, a first memory unit, a first stimulation unit configured to stimulate a human or animal heart, and a first detection unit configured to detect cardiac electrical signals of the same; the second leadless pacing device (2) comprising a second processor, a second memory unit, a second stimulation unit configured to stimulate the same heart as the first stimulation unit, and a second detection unit configured to detect the same cardiac electrical signals as the first detection unit; the second leadless pacing device (2) configured to operate in a standby state (20) or an active state (21); A cardiac pacing device (1), the second memory unit includes a second computer readable program; The second computer readable program, when executed on the second processor, causes the second processor to perform the following steps: a) determining (30) whether conditions (101, 102, 103) are met for transitioning the second leadless pacing device (2) from a standby state (20) to an active state (21), comprising: The conditions (101, 102, 103) are i) N successive stimulation pulses are emitted by the second stimulation unit, where N is an integer in the range of 2 to 10; ii) the second detection unit does not detect a stimulation pulse emitted from the first stimulation unit for a predetermined period of time ranging from 0.5 hours to 72 hours, and at the same time detects an existing intrinsic rhythm of the patient; and iii) detecting M consecutive non-captured stimulation pulses emitted by the first stimulation unit by the second detection unit, where M is an integer in the range of 2 to 10; Step (30), b) transitioning (40) the second leadless pacing device (2) from a standby state (20) to an active state (21) if the conditions (101, 102, 103) are met; This is to allow the A cardiac pacing device comprising:

2. 2. The cardiac pacing device of claim 1 , wherein operation of the second leadless pacing device in a standby state enables backup stimulation of the heart at a backup stimulation rate lower than a lowest stimulation rate delivered by the first stimulation unit of the first leadless pacing device, even during testing or application of hysteresis.

3. 3. The cardiac pacing device of claim 1 or 2, wherein the second leadless pacing device is configured such that at least some electrical consuming elements or electrical consuming operations of the second leadless pacing device not required for delivery of stimulation pulses by the second stimulation unit are deactivated when the second leadless pacing device is operating in a standby state.

4. 4. The cardiac pacing device of claim 3, wherein electrical consumption elements or activities of the second leadless pacing device not necessary for delivery of stimulation pulses by the second stimulation unit are selected from the group consisting of one or more sensors other than the second sensing unit, a statistical calculation unit relating to sensed electrical signals and / or delivered pacing pulses, and a measurement unit.

5. The second computer readable program may be configured to cause the second processor to: Responsive to the second leadless pacing device (2) transitioning from a standby state (20) to an active state (21), transmitting information to the first leadless pacing device (1) indicating that the second leadless pacing device (2) is operating in an active state.

5. A cardiac pacing device according to claim 1, for use in a cardiac pacing system.

6. the first memory unit includes a first computer readable program; The first computer readable program, when executed on the first processor, causes the first processor to: transitioning the first leadless pacing device (1) from an active state (11) to a standby state in response to receiving information indicating that the second leadless pacing device (2) is operating in an active state (21).

6. The cardiac pacing device of claim 5.

7. 7. The cardiac pacing device of claim 6, wherein operation of the first leadless pacing device in a standby state enables the first leadless pacing device to perform statistical calculations related to sensed electrical signals.

8. the first memory unit includes a first computer readable program; The first computer readable program, when executed on the first processor, causes the first processor to: transitioning the first leadless pacing device (1) from the active state (11) to an inactive state in response to receiving information indicating the second leadless pacing device (2) is operating in the active state (21).

6. The cardiac pacing device of claim 5.

9. A method for controlling a cardiac pacing device (3) according to any one of claims 1 to 8, said method comprising the following steps: a) determining (30) whether conditions (101, 102, 103) are met for transitioning a second leadless pacing device (2) from a standby state (20) to an active state (21), comprising: The conditions (101, 102, 103) are i) N successive stimulation pulses are emitted by the second stimulation unit, where N is an integer in the range of 2 to 10; ii) the second detection unit does not detect a stimulation pulse emitted from the first stimulation unit for a predetermined period of time ranging from 0.5 hours to 72 hours, and at the same time detects the patient's existing intrinsic rhythm; and iii) detecting M consecutive non-captured stimulation pulses emitted by the first stimulation unit by the second detection unit, where M is an integer in the range of 2 to 10; Step (30), b) transitioning (40) the second leadless pacing device (2) from a standby state (20) to an active state (21) if the conditions (101, 102, 103) are met; A method comprising:

10. A computer program product comprising computer readable code, The computer readable code, when executed by a processor, causes the processor to perform the following steps: a) determining (30) whether conditions (101, 102, 103) are met for transitioning a second leadless pacing device (2) from a standby state (20) to an active state (21), comprising: The conditions (101, 102, 103) are i) N successive stimulation pulses are delivered by a second stimulation unit of the second leadless pacing device (2), where N is an integer in the range of 2 to 10; ii) no stimulation pulses delivered by the first stimulation unit of the first leadless pacing device (1) are detected by a second detection unit of the second leadless pacing device (2) for a predetermined time period ranging from 0.5 hours to 72 hours while simultaneously detecting an existing intrinsic rhythm of the patient; and iii) detection by the second detection unit of M consecutive non-captured stimulation pulses delivered by a first stimulation unit of the first leadless pacing device (1), where M is an integer in the range of 2 to 10; Step (30), b) transitioning (40) the second leadless pacing device (2) from a standby state (20) to an active state (21) if the conditions (101, 102, 103) are met; A computer program product for causing the execution of the steps of:

11. A method for stimulating a patient's heart by means of a cardiac pacing device (3) according to any one of claims 1 to 8, said method comprising the following steps: a) determining (30) whether conditions (101, 102, 103) are met for transitioning a second leadless pacing device (2) from a standby state (20) to an active state (21), comprising: The conditions (101, 102, 103) are i) N successive stimulation pulses are emitted by the second stimulation unit, where N is an integer in the range of 2 to 10; ii) the second detection unit does not detect a stimulation pulse emitted from the first stimulation unit for a predetermined period of time ranging from 0.5 hours to 72 hours, and at the same time detects the patient's existing intrinsic rhythm; and iii) detecting M consecutive non-captured stimulation pulses emitted by the first stimulation unit by the second detection unit, where M is an integer in the range of 2 to 10; Step (30), b) transitioning (40) the second leadless pacing device (2) from a standby state (20) to an active state (21) if the conditions (101, 102, 103) are met; c) delivering at least one stimulation pulse to the patient's heart by the second stimulation unit; A method comprising:

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