Atrial Pacing Capture Confirmation Strategy in an Intracardiac Leadless Pacemaker

Abstract

The present disclosure relates to a leadless pacing device (100) for implantation in the atrium of the heart. The leadless device (100) comprises an implant anchor (110) for connecting the device to the inner wall of the atrium (A), a stimulator (120) for direct stimulation (410) of the atrium (A), and a sensor (130) for sensing ventricular activity of the heart in response to direct stimulation of the atrium. Further aspects relate to a system comprising such a leadless pacing device (100), a method (300), and a computer program that can be executed by such a leadless pacing device (100).

Description

Technical Field

[0001] The present invention generally relates to a leadless pacing device (e.g., a leadless pacemaker) that can be implantable in the atrium of the heart, and a system, method, and computer program for operating such a device, particularly for sensing ventricular activity of the heart in response to direct stimulation of the atrium.

Background Art

[0002] Devices that can be implanted in a patient to sense the activity of the patient's heart and / or to pace the heart or defibrillate the heart have been known for a long time. Conventionally, lead-based cardiac devices that can have their body units outside the heart (e.g., in the chest region) have been used, where the inner wall of the heart chamber can contact the end of a transvenous lead system extending from the body unit. More recently, such implants have been provided or presented as leadless devices. A leadless implant can be implanted directly into the heart in an implanted manner (e.g., a leadless implant does not include an external lead such as a transvenous lead for interacting with the heart). So far, leadless implants for implantation in the right ventricle have been used. Those leadless implants can facilitate cardiac treatment by directly contacting the ventricle as an implanted system.

[0003] Known leadless devices can include a stimulator and a sensor that directly contacts the inner wall of the right ventricle. This approach enables direct electrical stimulation (e.g., pacing) of the right ventricle and direct sensing of electrical signals corresponding to paced ventricular events. Thus, the leadless device enables treatment based on ventricular pacing and ventricular sensing, where a particular stimulation can be based on a particular ventricular activity (e.g., VVI mode).

[0004] It is desirable to also extend leadless device therapy to pacing devices placed in the atrium. Due to the size limitations of the atrium, the available battery size may be even more restricted than in the case of devices in the ventricle, so it is desirable to design such devices with low power consumption.

[0005] In the area of leaded pacemakers, devices that use atrial capture control to minimize power consumption are known. For example, it is known to sense atrial events for that purpose. However, this approach does not take into account further responses of the heart to atrial stimulation, such as ventricular activity or atrial evoked response signals. These heart responses can be particularly interesting for the treatment of bradycardia or sinus arrest. The feature support power levels associated with these legacy offerings may not be optimal, especially when considered in relation to leadless systems placed in the atrium and their associated constraints for onboard battery sizing.

[0006] Furthermore, lead-based systems can be disadvantaged compared to leadless systems due to the direct physical pathway for infectious diseases (especially those starting in the chest pocket of legacy devices) to approach the heart. Additionally, lead-based systems place a large amount of hardware in the patient's body that can be difficult to explant and include components that are subject to mechanical failure in the harsh physiological environment where the components are present. In fact, these troublesome problems (i.e., infection risk and lead failure) are what largely drove the emergence of leadless pacing.

[0007] Thus, overall, there is a tendency to replace lead-based devices with leadless devices, resulting in reduced stress on the patient, reduced infection risk, and reduced risk of device failure. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0008] Notwithstanding the foregoing, currently known techniques for leadless cardiac implants are not always optimal, particularly with regard to the control of their power consumption, which prompts a further need to improve leadless cardiac implants. Specifically, the stringent power limitations inherent to leadless pacemakers targeting the atria create a need for innovative strategies to reduce pacing output beyond standard pacer levels while maintaining safe and reliable treatment. **Means for Solving the Problems**

[0009] Aspects described herein at least partially address the above needs.

[0010] A first aspect relates to a leadless pacing device for implantation in the atria of the heart. The leadless pacing device may comprise an implant anchor for connecting the device to the inner wall of the atrium, a stimulator for direct stimulation of the atrium, and a sensor for sensing ventricular activity of the heart in response to direct stimulation of the atrium. The implant anchor may also be referred to as a connector.

[0011] This is based on the idea that a device that is entirely within the atrium can sense a ventricular response corresponding to direct stimulation of the atrium. This concept can be particularly interesting for cardiac therapies that may rely on atrial stimulation, especially when the atrial stimulation is intended to produce a ventricular response (e.g., for patients with bradycardia and / or sinus arrest). Thus, the purpose of atrial stimulation can be to cause a desired ventricular activity. For example, this can typically be a corresponding ventricular response (i.e., ventricular contraction). However, it is also possible that atrial stimulation for cardiac therapy is intended to cause an atrial response (e.g., atrial contraction), which can then be conducted to the ventricles and cause a ventricular response. In that regard, the atrial response can be determined by the corresponding ventricular activity. Overall, in some therapeutic uses of the leadless device, the atrial stimulation can be an input signal to the cardiac system, while the ventricular activity can be the desired output signal. The detected atrial response can also be another means for determining capture.

[0012] Thus, according to the above aspects, an optimized method for determining the functionality of a leadless device disposed in the atrium can be provided to enable sensing of a desired output (i.e., the corresponding ventricular activity). This enables not only verifying the overall functionality of the device (i.e., verifying that the desired output is achieved), but also optimizing power consumption by setting the stimulation power to a (minimum) level that still supports the intended ventricular response.

[0013] Prior art techniques based on leaded devices suffer from simply sensing atrial events that may not fully cover the intended therapeutic output. Thus, in such scenarios, a fixed high-output pacing setting that leads to excessive energy consumption may be required. In contrast, the present disclosure enables directly associating sensed ventricular activity (i.e., contractions) with paced atrial events, enabling optimized functionality checks and power control.

[0014] The implant anchor can provide a stable connection to the atrial wall such that direct stimulation of the atrium as well as reliable sensing of ventricular activity (e.g., via remote field sensing) can be provided.

[0015] The implant anchor can be configured to fixedly attach a leadless device to the inner wall of the atrium by providing a direct mechanical connection to the inner wall. The stimulator can be in the vicinity of the implant anchor such that the implant anchor can ensure direct electrical contact of the stimulator with the atrium. The implant anchor can be constructed as a base mount of the leadless device, e.g., a stable surgical fixation point and / or functioning as the bottom surface of the leadless device when implanted in the atrium. The stimulator can also be formed at the base of the leadless device. Thus, the stimulator can be, for example, directly pressed against the inner wall of the atrium by the implant anchor and thus directly apply myocardial stimulation to the atrium.

[0016] The sensor can be adapted to sense ventricular activity autonomously (i.e., without assistance from elements outside the atrium). The sensor and the stimulator for sensing ventricular activity can share at least partially elements (e.g., they can use the same electrodes), or the sensor and the stimulator can be separate elements of the leadless device (e.g., each can have separate electrodes). The sensor and / or the stimulator can be formed at the base of the leadless device. They (i.e., their electrodes) can be pressed directly against the inner wall of the atrium by an implant anchor, for example, in the same manner as outlined herein with respect to the stimulator. For example, the sensor can sense signals from ventricular activity in this regard (remote field sensing).

[0017] In another example, the device can be configured to determine the occurrence or absence of ventricular events corresponding to direct atrial stimulation, at least in part based on the sensed ventricular activity. The ventricular events can be occurring significant or minor ventricular activity (i.e., measurable ventricular contractions, or the absence thereof). The device can be configured to determine ventricular events based on the sensed ventricular activity. This can enable an accurate classification of ventricular activity as specific ventricular events corresponding to atrial stimulation.

[0018] Determination of ventricular events can be achieved by determining the presence of a pulse signal in the sensed ventricular activity signal. For example, determining can include the rising edge, falling edge and / or a specific threshold of the ventricular activity signal. The correspondence with direct atrial stimulation can be established, for example, based on ventricular events that occur after atrial stimulation but before the timer has elapsed. Additionally or alternatively, it is also possible to compare signal shapes, etc. to establish the correspondence.

[0019] Determination of ventricular events may also include the use of a detection algorithm that may consider at least one signal parameter (e.g., shape, amplitude, duration, frequency, etc.) of the corresponding ventricular activity to determine a particular ventricular event. For example, the detection algorithm may be configured to determine various types of ventricular events that may be related to the type of ventricular contraction (e.g., presence or absence of contraction, and / or type of presence contraction such as low / high amplitude condition, short / long duration, specific shape, etc.).

[0020] Determination of the occurrence or absence of the determined ventricular event can be evaluated in various ways (e.g., by Boolean logic). In one example, the device may test whether a predetermined ventricular event (e.g., a particular type outlined above) has been determined and may assign an attribute to the corresponding ventricular event to indicate its occurrence or absence. The device may be configured to accurately screen for one type of ventricular event (e.g., presence contraction), but may also be configured to screen for multiple types of ventricular events (e.g., presence contraction with a predetermined duration, etc.). The signal processing of the detection algorithm may include various steps, such as scaling, filtering, rectification, etc. Further, the device may include a high-gain amplifier for optimally converting the initially sensed signal for determination of ventricular events. The leadless device may be further configured to collect high-resolution and / or high-gain intracardiac electrogram (IEGM) data for use in the detection algorithm. The leadless device may include hardware for supporting the implementation of various types of signal processing.

[0021] In another example, the device may be configured to determine whether a given direct stimulation at a given stimulation power and / or a given stimulation energy leads to a corresponding ventricular event. For example, a direct stimulation at a given stimulation power and / or energy may be applied. Thereafter, based on the sensed ventricular activity, it may be determined whether a corresponding ventricular event has occurred. The stimulation may be, for example, at least one pulse having a specific energy. The pulse may have an effective power defined by the ratio of the pulse energy to its duration and / or its full width at half maximum (FWHM). In one example, the given stimulation may include various parameters (such as cycle length, current, voltage, pulse width, total power, average power, total energy, etc.), where the set of parameters may be related to the occurrence or absence of the corresponding ventricular event. The determined result may be stored by the device (e.g., in tabular form, in a database, etc.).

[0022] In a further example, the device may be configured to change the stimulation parameters of a given direct stimulation. For example, the device may be configured to change the stimulation power and / or the stimulation energy of the direct stimulation. For example, the device may include a power electronic circuit coupled to the stimulator to modulate the amount of stimulation power that can be applied to the atrium. The device may be further configured to adjust various further parameters of the direct stimulation (such as cycle length, current, voltage, pulse width, etc.). For example, pulses having a fixed duration are applied at different amplitudes, which may lead to different energies and powers. As a further example, the duration of a pulse having a fixed energy varies, which may lead to different powers but the same energy.

[0023] In another example, the device can be configured to perform a number of or multiple direct stimulations with different stimulation powers and / or energies to determine the threshold of the stimulation power and / or energy at which a ventricular event occurs. In one example, the device can be configured to determine the capture threshold of atrial stimulation. Capture can mean that the direct atrial stimulation effectively resulted in the occurrence of the desired ventricular event (e.g., a present ventricular contraction). The threshold can mean the capture threshold of the stimulation power at which the desired corresponding ventricular event occurs. An atrial stimulation power below the threshold can result in the absence of the desired corresponding ventricular event. In this case, the heart activity may not be sufficiently stimulated by the stimulation power to induce a corresponding response. To minimize the very significant power consumption in a leadless pacemaker platform, it can be important to determine the threshold of the stimulation power and / or energy. As a fully contained system placed within the atrium, battery replacement may not be possible (at least without surgery which can cause medical stress to the patient with the implant). Thus, lower power consumption can lead to a significant extension of the device lifespan and reduce premature battery replacement due to medical intervention.

[0024] For example, after determining the threshold, the device can apply subsequent stimulations at that threshold. Then, the determination routine can be performed again later (e.g., the determination routine can be performed once an hour, once a day, etc.) to verify whether the threshold is still correct. To avoid pacing at a power that is at risk of being too low, a safety margin can be added to the determined threshold, and then the device can operate accordingly. Also, the determination routine can be triggered on an event basis (e.g., at the time of implantation and / or follow-up).

[0025] For example, the device can be configured to adjust its atrial stimulation power according to a determined power threshold. This can be by a tracking mode, where the device performs threshold searches at regular time intervals to adjust its atrial stimulation power that can be used for therapeutic stimulation (e.g., pacing). This can minimize power consumption, avoid unnecessary high-power stimulation, while ensuring the functionality of the leadless pacing device and extending device life. In another example, periodic (e.g., cyclic) threshold measurements can be used to monitor the power threshold for statistical purposes that can be stored in the leadless pacing device for later readout (e.g., by a clinician or otherwise).

[0026] In one example, the device may be configured to determine a minimum threshold of stimulation power / energy that can lead to ventricular contractions by various algorithmic steps. The determination of the minimum threshold may also be referred to as threshold search. The determination may be based on the occurrence and at least one absence of at least one corresponding ventricular event. As an example, an initial direct atrial stimulation may be based on a first predetermined power (the following algorithms may also be based on stimulation energy and / or pulse duration instead of stimulation power, but this will not be repeated for brevity), which may, with a high probability, result in the occurrence of a corresponding ventricular event. This predetermined power may be a high output power known to cause ventricular contractions. If the device determines the absence of a corresponding ventricular event at the high output power, the next stimulation may be based on a higher output power up to the maximum power allowed by the device (e.g., in one or more steps). If the ventricular event still cannot be determined, an alert may be issued to an external device. If the device determines the occurrence of a corresponding ventricular event at the high output power (or a higher or possibly maximum output power), the next stimulation may be based on a power that is lower by a first increment than the high output power (or a higher or possibly maximum output power). Further, the device may determine whether successively lower powers result in the occurrence or absence of a corresponding ventricular event. If an occurrence is determined, the device may sequentially repeat steps with successively lower stimulation powers until the first absence of the corresponding ventricular event is determined at a first absence power. This may indicate that each stimulation power is near the threshold. In one example, the successively higher stimulation powers prior to the first absence power may be defined as the minimum threshold of stimulation power.

[0027] In another example, the first increment (i.e., the previous stimulus power difference) can be reduced to a second increment after the first absence is determined. This may enable a finer grid to determine the threshold power in subsequent stimulation steps, similar to that outlined above. For example, the device may further apply atrial stimulation at a power that is higher than the first absence power by a second increment and determine the occurrence or absence of a corresponding ventricular event. This step can be repeated until the occurrence of the corresponding event is determined, which can then be used as the minimum threshold. Various other power threshold search algorithms, not described for the sake of brevity, may be possible. For example, after finding the minimum threshold based on the second increment, a third increment smaller than the second increment may be used. The stimulation power can be reduced again in steps corresponding to the third increment, such as until the absence of the corresponding ventricular event is determined.

[0028] In one example, the device may be configured to sense ventricular activity and / or determine a ventricular event in a predetermined time window after direct stimulation. This can optimize the device's ability to detect corresponding ventricular activity as the detection is narrowed to a meaningful time window in which the corresponding ventricular activity can be expected. This can separate interference signals and / or ventricular activity not related to atrial stimulation. This can further significantly reduce the computational complexity of the signal evaluation of ventricular activity performed by the detection algorithm as the ventricular signal is reduced to the relevant monitoring window. Additionally, this can reduce the power consumption by the device for the reduction in computational complexity (which may only require computational steps for the signal data within the time window according to the concepts of the present invention). This technique of narrowing signal detection to a time window can be used in the threshold search outlined herein. Thus, a large number of possible steps of the threshold search may require significantly less effort to determine the occurrence or absence of a ventricular event and can significantly reduce the power consumption of the leadless device.

[0029] In one example, the device can be configured to determine at least one parameter of the time window, based at least in part on data stored by the device regarding at least one previously measured time interval of the heart. In one example, the at least one parameter can include the start, center, duration, and / or end of the time window. The parameters of the time window can be based on a time relative to atrial stimulation (e.g., the start of atrial stimulation can be considered the initial time), where the time window parameters are based on the initial time. The data can be based on the patient's ApVs (atrial pacing, ventricular sensing) interval history. The history can be based on at least one previously determined ApVs interval for therapeutic purposes and / or for test stimulation. The history can also be based on one or more parameters of a previous time window used to determine corresponding ventricular activity and / or ventricular events, as outlined herein. The at least one parameter can be set to match at least one parameter of the last saved ApVs interval (e.g., the center of the time window). In one example, the time window duration can have a fixed value that can account for cycle-to-cycle variability of ventricular events, where only the center of the time window is determined based on the previous ApVs interval. In other examples, the time window duration can also be set based on the stored data, taking into account patient-specific irregularities. The at least one parameter can also be set to the average of a (short) history of determined ApVs intervals derived from a buffer history or a rolling window assessment.

[0030] In one example, the device may be configured to determine at least one parameter of the time window based at least in part on performing a test stimulus with a test stimulus power and / or a test stimulus energy (or any other stimulus parameter outlined herein) and sensing a corresponding ventricular activity. The underlying idea focuses on causing a desired corresponding ventricular event with the test stimulus and quantitatively determining the time window parameter thereof. As an example, this may take the form of an initialization phase where a high-power atrial stimulus that is expected to cause the occurrence of a corresponding ventricular event / contraction is applied (e.g., as part of the threshold determination routine outlined above). After the high-power atrial stimulus, ventricular activity may be continuously sensed, which may enable the device to ultimately pick up the signal of the corresponding ventricular event. The device may be configured to determine the occurrence of the ventricular event from the continuous ventricular signal as well as to determine further parameters of the ventricular event related to the time at which the high-power atrial stimulus occurred. This approach may enable the determination of at least one time window parameter related to the time window in which the ventricular event occurs (e.g., the duration of the ventricular event and when the ventricular event occurred after atrial stimulation). As an example, the device may be configured to implement respective ApVs detection algorithms to determine the time window (and / or at least one parameter of the time window) in which the corresponding ventricular event occurs. The device may then be configured to determine the threshold of the stimulus power at various stimulus powers at which the ventricular event occurs, but the determination of occurrence or absence may be narrowed to the most recently determined time window as outlined herein. In some cases, the window may be adjusted after the sensing step taking into account possible drifts, e.g., if the event is detected outside the center of the window.

[0031] This approach may initially require a higher signal processing complexity (e.g., as required by an ApVs detection algorithm), but it may enable the determination of an appropriate time window based on the latest measurements, which can then be used not only later to operate the device, but potentially also for an already existing threshold processing routine. For both applications, this approach can greatly reduce the risk of using an incorrect time window that can lead to false negative results in the determination of ventricular events.

[0032] During power threshold determination, it may be necessary to have stable conduction from the atrium to the ventricle (e.g., 1:1 AV conduction). To achieve a stable ApVs rhythm during testing, the atrial stimulation rate (i.e., pacing rate) can be increased to overdrive the intrinsic activity of the heart, and the AV pacing delay can be extended to facilitate sensing. In a further example, high-output atrial stimulation can be applied after all stimulation portions of the threshold determination (e.g., high-output stimulation follows all stimulation steps of the threshold search). This can maintain stable ApVs during further threshold determination steps.

[0033] In one example, the sensor can be configured for remote field sensing. Since the interference by the atrial signal (P wave) is relatively weak, remote field sensing of ventricular activity by a device placed in the atrium can be advantageous because the (relatively strong) ventricular signal (R wave) can still be determined within the atrium with a beneficial signal-to-noise ratio. Thus, ventricular events (e.g., contractions) can be reliably derived from the sensor's signal. For example, the sensor can detect the electrical signal of remote field ventricular activity picked up in the atrium to which the sensor can be directly connected. Remote field sensing may require specific signal processing to be performed by the device. For example, this may require filtering the atrial signal and determining whether the signal is of ventricular origin.

[0034] Note that the sensor can be understood as an integral part of an atrial implant device for performing remote sensing of ventricular activity.

[0035] In another example, the sensor may be based on a mechanical signal of ventricular activity, where the leadless device may comprise an accelerometer (and / or any other motion detector) for sensing ventricular activity. The accelerometer may be configured to provide a signal that enables sensing of ventricular activity from the mechanical signature generated by ventricular activity within the atrium (from the atrium). Also, in this way, reliable measurement of relatively strong ventricular activity (or the corresponding mechanical signature within the atrium) can be facilitated.

[0036] In one example, the sensor may be configured to receive information regarding ventricular activity from at least one first additional sensor for implantation in the ventricles of the heart, additionally or alternatively. Thus, the device may be configured to determine ventricular activity corresponding to atrial stimulation based on the sensed data of the first additional sensor that may be implanted in the ventricles. The information regarding ventricular activity may be based on directly sensed ventricular activity, for example, from signals picked up directly from the inner wall of the ventricles.

[0037] A second aspect relates to a system that may comprise a leadless pacing device and at least one first additional sensor. The device within the system may be configured as outlined herein. In one example, the leadless pacing device may be disposed in the right atrium, where the at least one first additional sensor may be disposed in the right ventricle. The system may further comprise a plurality of first additional sensors that may be disposed in the ventricles, where the leadless pacing device may also be disposed in the left atrium.

[0038] In one example, the first additional sensor can be a sensor disposed in the (right) ventricle that includes passive components. For example, the first additional sensor can include a capacitor coupled to the ventricle (e.g., to the inner wall of the ventricle or to ventricular myocytes), where the dielectric component thereof can be configured to be exposed to the electrical influence of the ventricle. Thus, the electrical excitation of the ventricle (e.g., ventricular myocytes) can cause a change in the electric field of the dielectric component of the capacitor, which can lead to a change in the capacitance of the capacitor. Accordingly, the first additional sensor can sense ventricular depolarization (i.e., ventricular activity) based on the change in capacitance. The first additional sensor can include a resonant circuit that the capacitor can be a part of or can be coupled to, which can provide a means for reading out the capacitance change. For example, the capacitor can be coupled to an inductance (e.g., a coil structure) within the resonant circuit. This can form a resonant frequency that depends on the capacitance of the capacitor. Changes in ventricular activity can be sensed by a change in the resonant frequency. An antenna can relay the sensed information (e.g., a change in the resonant frequency) to a leadless device (within the atrium). For example, the information can be transmitted from the antenna to a receiver unit of the leadless device, and the device can be configured to apply further processing of the information to determine ventricular activity. The antenna can be provided in the resonant circuit and / or can be provided in the leadless device. In one example, the antenna can include an inductance that is connected to the capacitor.

[0039] In particular, at least one first additional sensor, which can be for implantation in the ventricle, can be configured to sense ventricular activity and transmit information regarding ventricular activity to a leadless device for implantation in the atrium, and is also a separate part of the present disclosure. The first additional sensor can have its own power source, but can also be constructed to operate without an internal power source.

[0040] In one example, the system may comprise one or more additional leadless devices. In that case, for example, the system may be configured to sense ventricular activity of the heart corresponding to direct atrial stimulation based on ventricular activity sensed in a plurality of system devices. The system may be configured for device - to - device communication. In one example, a first additional leadless device may sense (e.g., directly) ventricular activity within the ventricle and transmit a sensory input to a leadless pacing device within the atrium. The sensory data may be received and used for further processing by the leadless pacing device. This can be very beneficial for power threshold determination as described herein because sensory data near the ventricle can be taken into account, which can reduce the need to filter interference signals as in the case of atrial - based remote field sensing. The sensory data of the first additional sensor may only be taken into account in certain steps of the power threshold search (or determination of ventricular activity and / or events corresponding to atrial stimulation). As an example, as outlined above, after a test stimulation with a test stimulation power, the correspondingly sensed ventricular activity may be determined based, additionally or alternatively, on sensory data from the first additional device. This can minimize the time - window parameters that are mis - determined because the signal is based on a very reliable signal directly from the ventricle. During further threshold search steps (e.g., after the time - window parameters have been determined), the determination of occurrence or absence may be based on sensory input from the leadless device within the atrium. This can reduce the computational complexity because the determination of occurrence or absence may not require as much effort to be made by the leadless pacing device itself and may not require a very pure signal strength (e.g., because the contraction only needs to be easily confirmed and not necessarily measured in detail).

[0041] In one example, the leadless device may include a second additional sensor for directly sensing atrial activity of the heart corresponding to direct stimulation of the atrium. The second sensor may be configured for near-field sensing. This concept may enable the device to sense atrial evoked response signals and / or sense atrial events. The atrial evoked response signal may be a direct response signal of the atrial myocardium to atrial stimulation. The second additional sensor may share one or more portions with the sensor, the first additional sensor, and / or the stimulator, or may have separate portions (e.g., one or more electrodes). The second additional sensor may comprise, for example, the same electrodes as the sensor and / or the stimulator. The second additional sensor may be constructed with a fractal coating that may be a conductive material irregularly deposited on the sensor surface. This may increase the electrochemically active surface area, which may reduce pacing polarization artifacts and / or increase the amplitude of the atrial evoked response. Thus, this may enable the second additional sensor to pick up atrial evoked response signals without significant interference at the device-tissue interface and accurately determine the atrial evoked response. This exemplary pacing device capable of directly sensing atrial activity may also be incorporated into the systems outlined herein. The stimulator and / or sensor may also comprise a fractal coating without being specifically designed for near-field sensing as the second additional sensor.

[0042] Note that the sensor and what is referred to as a second additional sensor can both be implemented within a single sensor unit (e.g., comprising a single electrode or a set of electrodes). For example, the sensor unit can comprise an electrode or a set of electrodes as described herein. Electrical signals including P-wave signals and R-wave signals (remote field signals) when the signal is picked up on the atrial wall can be picked up from the electrode or the set of electrodes. For example, the R-wave signals and P-wave signals are extracted by one or more filters (e.g., time domain and / or frequency domain) and can be evaluated separately (e.g., by different algorithms and / or different electronic components of the sensor unit implementing the first and second sensors). Accordingly, the aspects described herein with respect to the sensor and the second additional sensor are also applicable to other sensors respectively.

[0043] A third aspect relates to a method for determining a stimulation response performed by a leadless pacing device implanted in the atrium of the heart. The method can include performing direct stimulation of the atrium of the heart by the device at a predetermined stimulation power and / or a predetermined stimulation energy. Further, the method can include sensing the ventricular activity of the heart corresponding to the direct stimulation by the device. Further, the method can include determining the occurrence or absence of a ventricular event corresponding to the direct stimulation.

[0044] In one example, the method further includes performing a number of or a plurality of direct stimulations with different stimulation powers and / or different stimulation energies to determine a threshold of the stimulation power and / or the stimulation energy at which a ventricular event occurs. In other examples, one or more other parameters of a predetermined direct stimulation can be changed to determine the corresponding threshold.

[0045] A fourth aspect relates to a computer program that, when executed by a computer, may include instructions for performing any of the methods described herein. For example, the computer program may be stored in a leadless device, or a device within the system described herein, that may include means for executing the computer program instructions. The computer program may enable a self - contained and automatic implementation of the aspects described herein. As a result, technical intervention from medical staff and patients can be minimized.

[0046] The above is mainly related to sensing ventricular activity, which is not an essential part of the present disclosure. In one aspect, a leadless pacing device for implantation in the atrium of the heart may be provided, comprising an implant anchor for connecting the device to the inner wall of the atrium, a stimulator for direct stimulation of the atrium, and a sensor for directly sensing the atrial activity of the heart corresponding to the direct stimulation of the atrium. The leadless device may be further configured to perform the steps outlined herein mainly with respect to the sensed ventricular activity, additionally or alternatively, with respect to the sensed atrial activity, for example, to determine whether a direct stimulation leads to a corresponding atrial event, to determine a threshold, and / or to sense atrial activity within a predetermined time window. Alternatively or additionally, the device may be configured to determine whether a direct stimulation at a predetermined stimulation power and / or a predetermined stimulation energy leads to a corresponding ventricular event.

[0047] Similarly, in one aspect, a method for determining a stimulation response performed by a leadless pacing device implanted in the atrium of the heart may be provided. The method may include performing a direct stimulation of the atrium of the heart by the device at a predetermined stimulation power and / or a predetermined stimulation energy. Further, the method may include directly sensing the atrial activity of the heart corresponding to the direct stimulation by the device. Further, the method may include determining the occurrence or absence of an atrial event corresponding to the direct stimulation.

[0048] It should be noted that the method steps described herein may include all aspects described herein, even if they are not explicitly described as method steps but rather are described with respect to an apparatus (or device). Further, the devices outlined herein may include means for implementing all aspects outlined herein, even if they may be described rather in the context of method steps.

[0049] Regardless of whether they are described as method steps, computer programs, and / or means, the functions described herein may be implemented in hardware, software, firmware, and / or combinations thereof. When implemented in software / firmware, the functions may be stored on a computer-readable medium or sent as one or more instructions or codes on a computer-readable medium. A computer-readable medium includes both a computer storage medium and a communication medium that facilitates transfer of a computer program from one place to another. The storage medium can be any available medium that can be accessed by a general-purpose or special-purpose computer. By way of example, and not limitation, such computer-readable storage media can include RAM, ROM, EEPROM, FPGA, CD / DVD or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor. BRIEF DESCRIPTION OF THE DRAWINGS

[0050]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0051] FIG. 1 shows a schematic diagram of an exemplary leadless pacing device 100 according to the present invention.

[0052] The leadless pacing device 100 can be part of a system S that optionally includes a first additional sensor 200, where the first additional sensor 200 can be implantable in the ventricle V.

[0053] The leadless device 100 can be implanted in the atrium A of the heart (e.g., the atrium A of a human heart). The leadless device 100 can be specifically configured to be implanted, for example, in the right atrium of a patient.

[0054] The leadless pacing device 100 can include an implant anchor 110 for mechanically connecting the leadless device 100 to the inner wall of the atrium A. The implant anchor 110 can be constructed as a base mount of the leadless device 100 that can function as a surgical fixation point during the implantation procedure. The implant anchor 110 can include one or more fixation tines and / or anchor structures and / or screw fixation mechanisms to enable a stable and reliable connection to the atrium A.

[0055] The leadless pacing device 100 may further comprise a stimulator 120. The stimulator 120 may be configured to apply an electrical stimulus to the inner wall of the atrium A. The stimulator 120 may be configured to deliver a specific amount of electrical energy to the atrium A. The stimulator 120 may be connected to a power electronics circuit that can provide a defined energy for stimulation (e.g., in the form of one or more stimulation bursts). The stimulation may be for the purposes of testing, calibration, underlying bradycardia and / or anti-tachycardia pacing. The stimulator may include a conductive material formed by an electrode (e.g., a cathode or an anode) that can provide a direct electrical connection to the wall of the atrium A to transmit the electrical energy of the stimulator to the surrounding tissue.

[0056] The amount of electrical energy applied by the stimulator 120 may be adjustable. For example, the electrical energy may be applied in the form of pulses having adjustable energy and / or adjustable pulse timing or frequency. Further adjustable parameters may be the (average) power, cycle length, current, voltage, pulse width, FWHM, etc. of the applied electrical stimulus. The electrical energy and / or pulse parameters may be determined by the leadless device 100 or the system S (e.g., in response to sensed ventricular activity and / or atrial activity).

[0057] The leadless device 100 may further comprise a sensor 130 (disposed within the atrium A and being part of the leadless device 100). In one example, the sensor 130 may be configured to indirectly measure ventricular activity by sensing signals from the ventricle V of the heart (e.g., the right ventricle) (e.g., remote field sensing and / or accelerometer-based sensing). In the case of remote field sensing, the sensor 130 may be configured to make direct contact with the inner wall of the atrium A such that an electrical connection is established. In particular, the sensor 130 may be further configured to sense electrical signals (e.g., R-wave signals) present within the atrium A indicative of ventricular activity. The sensor 130 may include a conductive material formed by electrodes (e.g., a cathode or an anode) to pick up each electrical signal directly from the inner wall of the atrium A. The sensor 130 or its electrodes may include a coating (e.g., by zinc plating), a texture (e.g., having sized porosity) and / or a specific shape (e.g., a screw shape, a flat circular shape, etc.) optimized with respect to the characteristics of the inner wall of the atrium A to ensure a well-functioning sensing contact. As an example, ventricular activity may be determined to correspond to atrial stimulation.

[0058] In one example, the sensor 130 and / or the stimulator 120 may share elements with the implant anchor 110 and thus enable mechanical fixation and sensing / stimulation functions of the leadless device 100 by an electrode that also at least partially serves to mechanically connect the leadless device 100 to the wall of the atrium A, e.g., a single structural element.

[0059] The leadless device 100 may further comprise a second additional sensor 150. The second additional sensor 150 may be in direct contact with the inner wall of the atrium A so that an electrical connection is established. Thus, the second additional sensor 150 may enable short-range field sensing and may be configured to sense atrial activity (e.g., P-wave signal). In one example, the sensor 150 may also be configured to sense and / or determine an atrial evoked response signal (i.e., the direct response of atrial myocardium to atrial stimulation). The sensor 150 may include a conductive material that may be formed by electrodes (e.g., cathode or anode) to directly pick up respective electrical signals from the inner wall of the atrium A. The second additional sensor 150 (e.g., especially its electrodes) may have a fractal coating on the surface that functions as contact to the surrounding (atrial) tissue. The fractal coating may be a conductive material (e.g., iridium, titanium nitride) that may be deposited to form an irregular shape at the microscopic scale. Thus, the coating may significantly increase the electrochemically active surface area, which is beneficial for determining the atrial evoked response. Thus, this may enable the second additional sensor to pick up the atrial evoked response signal without significant interference at the device-tissue interface and accurately determine the atrial evoked response. For example, the fractal coating may ensure that the polarization artifact remains consistent, which may then be accurately considered in further signal processing. This may reduce or completely prevent false positive and / or false negative detections. The atrial evoked response may be determined, for example, to correspond to atrial stimulation.

[0060] The stimulator 120, the sensor 130, and / or the second additional sensor 150 may share one or more electrodes and / or may have separate electrodes. The stimulator 120 and / or the sensor 130 may also have the fractal coating described for the second additional sensor 150 when their electrodes are shared with the second additional sensor or when their respective electrodes are separate.

[0061] As outlined above, in some examples, the functionality of sensor 130 and the second additional sensor 150 may be provided by a (single) sensor unit of the wireless device 100. In some examples, the wireless device 100 may include a sensor unit that implements the functionality of the second additional sensor 150 and / or sensor 130, instead of the second additional sensor 150 and sensor 130.

[0062] The wireless device 100 may further include a battery 140 that can function as a power source for the wireless device 100. The battery 140 may have a form factor that is slightly smaller compared to batteries used for devices implanted in the ventricles, due to the small size of the atrium A.

[0063] Furthermore, the wireless device may include a control unit 160. The control unit 160 can be at least one computing unit (e.g., a microprocessor, a microcontroller, an embedded system, an electronic circuit, etc.) that can implement computing instructions. The control unit 160 can control various device elements based on a configuration that can be defined by the computing instructions (e.g., by a computer program executed on the control unit 160). The control unit 160 can be connected to the various device elements outlined above (e.g., via one or more input / output ports for respective electrical signaling) to control and / or receive / send information. The control unit 160 can, for example, receive sensory input from the sensors outlined in this specification and apply further signal processing (e.g., scaling, filtering, rectification). The control unit 160 can have its own memory and / or can be coupled to a separate memory provided in the wireless device 100.

[0064] The control unit 160 described in this specification can also be implemented in hardware, software, firmware, and / or combinations thereof, for example, by one or more general-purpose or dedicated processors and / or microcontrollers.

[0065] The control unit 160 may be coupled to the stimulator 120 and / or the power electronics circuit of the stimulator 120, where a particular signaling of the control unit 160 may produce a desired stimulation output according to a set of stimulation parameters on the atrium A of the heart via the stimulator 120. Thus, the control unit 160 may control the stimulation output within the atrium A, which may be based on several input factors that may be processed and analyzed by the control unit 160. As an example, the paced output may be a response to ventricular activity and / or atrial activity corresponding to the previous atrial stimulation. Thus, the control unit 160 may enable various implementations of cardiac therapy by the device. As an example, the leadless pacing device 100 may be configured to support AAI mode cardiac therapy for patients with sinus node dysfunction.

[0066] Note that the manner in which the interaction between the control unit 160 and the stimulator 120 and the sensors 130 and 150 has been described is merely optional. At least some of the functions of the control unit 160 may be performed by the sensors themselves. For example, the second additional sensor 150 may share electrodes with the sensor 130 in some instances such that their signals may be physically picked up by the same element. However, they may include different signal processing / filtering, etc. for deriving atrial and ventricular activity, respectively, that is performed by one or more control units.

[0067] System S may optionally include a first additional sensor 200 according to the present invention, shown by the dashed line in FIG. 1. The first additional sensor 200 may be implanted in the ventricle V of the heart (e.g., the ventricle V of a human heart). The first additional sensor 200 may be particularly configured to be implanted in the right ventricle of the patient. In one example, the first additional sensor 200 may be a passive sensor that detects ventricular activity. The first additional sensor 200 may include a capacitor 210 as a passive sensor, and the passive sensor may be implanted in the ventricle V such that it is aligned with ventricular activity. The capacitor 210 may be aligned within the tissue such that the ventricular activity of nearby muscle cells can affect the electrical properties of the capacitor 210. For example, the capacitor 210 may include a dielectric medium interposed between conductors. The first additional sensor 200 may be configured such that the electric field of ventricular tissue depolarization affects the dielectric medium, which leads to a change in the dielectric medium and a change in the capacitance of the capacitor 210. In another example, the mechanical contraction of ventricular cells can affect the mechanical properties of the capacitor 210 (e.g., the distance between the capacitor plates and / or the area of the capacitor plates), which can lead to a change in the capacitance of the capacitor 210. The capacitor 210 may be coupled to an inductor (not shown) to form a resonant circuit. In that case, the resonant frequency of the resonant circuit depends on the capacitance of the capacitor 210 and the inductance of the inductor. The inductance of the inductor may be designed to have a fixed value, where the inductor may be configured such that its inductance does not change significantly under the direct influence of ventricular contraction and / or excitation. Thus, the resonant frequency of the resonant circuit may depend greatly on the value of the capacitance of the capacitor 210 (rather than the inductance) under ventricular activity. Thus, reading the resonant frequency corresponding to the change in the capacitance of the capacitor 210 may enable reading of ventricular activity. In one example, the resonant circuit within the ventricle V may include an antenna 220 connected to the inductor. The antenna 220 may relay information about the resonant circuit (e.g., resonant frequency, change in resonant frequency, change in capacitance, and / or its own capacitance) to the leadless device 100 disposed in the atrium A. The leadless device 100 may include a receiver unit for receiving the information.The receiver unit can be coupled to a control unit 160 that can further process the signal. In another example, the antenna 220 can be provided in the leadless device 100 disposed in the atrium, and the antenna 220 is coupled to a resonant circuit and configured to read out the resonant circuit parameters as outlined above. The first additional sensor 200 can include a power source to ensure its operation. In another example, the first additional sensor 200 can be configured not to require an internal power source for detecting ventricular activity.

[0068] In one example, the first additional sensor 200 can be provided by a leadless pacing device disposed in the ventricle and configured to directly sense ventricular activity. The leadless pacing device disposed in the ventricle can include device elements similar to those described herein for the leadless device 100 in the atrium. The device elements can have features configured for the ventricle V. Optional ventricular leadless pacing devices and the leadless pacing device 100 can be configured for device - to - device communication such that sensed activity is requested and can be exchanged between devices, similar to the relay of pacing commands.

[0069] FIG. 2 shows a schematic diagram of an exemplary method 300 according to the present invention for determining the stimulus response performed by a leadless pacing device implanted in the atrium of the heart. The method can be implemented by a leadless device 100 implanted in the atrium A of the heart (e.g., by the control unit 160 of the leadless device 100). The method can also be implemented by a leadless device 100 configured in the system S configuration outlined herein.

[0070] Method 300 may include performing 310 direct stimulation of the atrium of the heart by the leadless device 100 at a predetermined stimulation power and / or a predetermined stimulation energy. The direct stimulation may be based on stimulation parameters or a set of stimulation parameters (e.g., cycle length, current, voltage, pulse width, total power, average power, total energy, etc.) corresponding to the power and / or electrical energy of the stimulation. For example, the direct stimulation may include a fixed pulse duration, where the pulse amplitude may be adjusted to match the stimulation power. In particular, the stimulation power and / or stimulation energy (and / or stimulation parameters) may be set by the control unit 160. The control unit 160 may activate the stimulation that may be performed by the stimulator 120.

[0071] Subsequently, method 300 may include sensing 320 the ventricular activity of the heart corresponding to the direct stimulation of the device. The ventricular activity as a cardiac response may be medically related to the corresponding atrial stimulation. For example, the atrial stimulation may induce an atrial signal that may be conducted along the heart to the ventricles and cause a corresponding ventricular activity (e.g., ventricular contraction) as a cardiac response. Additionally or alternatively, the method may include sensing the atrial activity of the heart (e.g., atrial events and / or atrial evoked response signals) corresponding to the direct stimulation of the device. For example, as described above, the atrial stimulation may also induce an atrial signal as a directly sensed cardiac response.

[0072] The ventricular activity may be sensed by the sensor 130 and / or the first additional sensor 200, and the atrial activity may be sensed by the second additional sensor 150. The sensed data may be transferred to the control unit 160, which may apply initial signal processing (e.g., high-gain signal amplification). The control unit 160 may be further configured to control the resolution of the sensed data, which may be performed by adapting the sensor settings and / or by post-processing the raw sensor data. This may enable the leadless device 100 to collect high-resolution data that may also include high-gain signals of the intracardiac electrogram (IEGM). This processing may ensure reliable signal quality for further processing steps.

[0073] As outlined herein, sensor 130 and / or the second additional sensor 150 may be implemented as a (single) sensor unit, such as to implement two different sensor functions, for example, using different channels for the far-field channel and / or the near-field signal, respectively.

[0074] Subsequently, method 300 may include determining 330 the occurrence or absence of ventricular events corresponding to direct stimulation. The corresponding ventricular events may be ventricular contractions that occur in response to the applied atrial stimulation. Additionally or alternatively, method 300 may include determining the occurrence or absence of atrial events and / or atrial evoked responses corresponding to direct stimulation. The atrial event may be an atrial contraction, and the atrial evoked response may be a specific signature of an atrial evoked response signal. The determination of ventricular events, atrial events and / or atrial evoked responses may be performed by respective detection algorithms that may be implemented by control unit 160. Each detection algorithm may require signal processing (such as scaling, filtering, rectification, signal amplification, etc.).

[0075] Method 300 may further include performing 340 a number of direct stimulations (of atrium A) with different stimulation powers and / or different stimulation energies in order to determine the threshold of the stimulation power and / or stimulation energy at which ventricular events (and / or atrial events and / or atrial evoked responses) occur. This may enable the determination of the minimum stimulation power and / or minimum stimulation energy at which the occurrence of ventricular events (and / or atrial events and / or atrial evoked responses) can still occur. The method step 340 of performing may be performed by sequentially repeating the steps of performing 310, sensing 320, and determining 330, where each sequence may be based on stimulations with different stimulation powers and / or different stimulation energies that may be adjusted after each sequence as outlined herein. Sequential stimulation is sometimes referred to as search stimulation.

[0076] Accordingly, method 300 may enable various types of atrial capture threshold searches for various cardiac responses (e.g., ventricular events, atrial events, atrial induced responses) to atrial stimulation. Successful atrial capture may be understood as the occurrence of a specific cardiac response (i.e., capture confirmation) to atrial stimulation. Unsuccessful atrial capture may be understood as the absence of a specific cardiac response (i.e., capture loss) to atrial stimulation.

[0077] Atrial capture threshold search may search for values of atrial stimulation power and / or stimulation energy (and / or any other stimulation parameter) that mark the minimum threshold for achieving a specific cardiac response. A specific cardiac response may not greatly depend on the amount of stimulation parameters of the stimulation, but may simply depend on the stimulation parameters that are above or below that specific threshold. For example, the applicable stimulation power of a leadless device may vary within a specific range. The minimum threshold of the cardiac response (which may be patient-specific) may be, for example, 30% of that range. Stimulation with a power level of 30% or more may result in a specific cardiac response, and stimulation with a power level below 30% may not cause a specific cardiac response.

[0078] For the sake of brevity, atrial capture threshold search is described in more detail in the example of ventricular contraction as a specific cardiac response to atrial stimulation. However, this is for illustrative purposes only, and in other examples, method 300 may be based on different cardiac responses (i.e., different ventricular signals, atrial events and / or atrial induced responses).

[0079] To determine the threshold, leadless pacing device 100 may evaluate a series of search stimuli (i.e., atrial search paces) and determine the respective conducted ventricular activity, as outlined for method 300. The step 320 of sensing ventricular activity and the step 330 of determining may be narrowed to a time window after the search stimulus.

[0080] An exemplary timing diagram 400 of FIG. 3 shows an exemplary time window 420. In particular, when the time window 420 is used (e.g., in method 300), ventricular activity outside the time window 420 may not be sensed and / or may not be considered for the determining step 340. Only the signals within the time window 420 may be regarded as relevant. This can significantly reduce the computational complexity for the control unit 160, save power consumption, and lead to an extended device life. The time window 420 may be related to an expected Vs (ventricular sensing) window assumed for the typical AV delay of the heart. The AV delay may be related to the signal conduction from the atrium to the ventricle. The AV delay may be regarded as the time when ventricular contraction normally occurs after atrial stimulation. During atrial capture threshold search, a certain AV delay and / or a stable ApVs (atrial pacing, ventricular sensing) rhythm may be achieved by changing the atrial stimulation frequency, and the atrial stimulation frequency may be increased, for example, to overdrive the intrinsic heart activity. This can achieve a stable 1-to-1 AV conduction. Further, the AV pacing delay may be extended to facilitate sensing. Overall, the atrial stimulation parameters may be adapted during capture threshold search to ensure that the response of ventricular activity occurs reliably within the time window 420 after atrial stimulation. This may enable narrowing the confirmation of capture or loss of capture to the time window 420 after the exploration stimulus 410 is applied.

[0081] In FIG. 3, a time window 420 is shown on a time scale with respect to an atrial exploration stimulus 410. The atrial exploration stimulus 410 can occur at time t0. The time window can be set to be within the period in which a ventricular response is expected if successful capture occurs, as outlined herein. The time window 420 can have a time window length defined by two time values indicating the start time t1 and the end time t2 of the time window 420. The times t1 and t2 can be returned to the time t0 which can be defined with the initial reference time t0 = 0 when the atrial stimulus occurred. For example, after applying an atrial stimulus (e.g., by a time counter), time measurement can be started. Time can be measured by the control unit 160 and / or by an additional time unit provided in the leadless device 100. An important parameter of the time window 420 can be the central time t C which can be, and the central time t C is, t C =(t2 + t1) / 2 which can be calculated. The central time t C can be set to be within the amplitude peak (or the center of the distribution) of the expected ventricular contraction signal. The time window length (t2 - t1) can be set to take into account the cycle-to-cycle variation of ventricular contraction. This can ensure that even when the signal of ventricular contraction is slightly shifted, the signal related to the occurrence of ventricular contraction can still be determined within the time window 420.

[0082] The parameters of the time window 420 can be based on the patient's ApVs interval history. The central time t C can be set to match the last saved ApVs interval or the average of a short buffer history of ApVs intervals.

[0083] Capture search is the continuous measurement of ventricular activity after a test stimulus for the parameters of the time window (e.g., t C, including an initialization stage for determining (e.g., t1, t2, window length, etc.). The test stimulus may include a parameter (e.g., a high-output pulse) or a set of parameters expected to normally capture ventricular contraction. Subsequently, as outlined herein, the control unit 160 may analyze the signal of the continuous measurement of ventricular activity and determine at least one time window parameter. In one example, the test stimulus may be performed to determine only the central time t C , where the window length may be based on a predetermined window length that can be specified by a clinician and / or technician (i.e., by the external configuration of the leadless device 100). During the initialization stage, atrial stimulation parameters (e.g., atrial stimulation rate) may be adapted to the same conditions as during threshold search to achieve stable conduction conditions to ensure that the determined time window parameter is the same during capture threshold search. This means that several test stimuli are implemented. Then, continuous measurements may be performed after one or a subset of the test stimuli, or in some cases, after each of the test stimuli.

[0084] Thus, returning to FIG. 2, particularly in step 340, the sub-steps of sensing and / or determining can be narrowed to the time window 420 without loss of information, regardless of whether successful capture has occurred. The threshold search may be based on progressively sweeping the parameter (or set of parameters) of the stimulus and determining whether each stimulus results in a capture confirmation or capture loss within the time window 420. As outlined herein, the threshold search may start with a high-power stimulus expected to capture, then reach near the threshold, and finally gradually decrease the power of the stimulus to determine the threshold. Various other threshold search algorithms may be applied.

[0085] As an example, the threshold search can be optimized to require as few steps as possible, which can be achieved by starting the threshold search based on the stored threshold. The stored threshold can be the last saved threshold or the average of a short buffer history of previous thresholds. In a further example, the time window parameter can be determined after each threshold search step or at a specific point in the threshold search (e.g., after a specific step). For example, after a successful capture threshold determination, the time window parameters can be determined again as a confirmation to ensure that they have not drifted during the search.

Claims

1. A leadless pacing device (100) for implantation in the atrium (A) of the heart, wherein the leadless pacing device (100) is An implant anchor (110) for connecting the device to the inner wall of the atrium, A stimulator (120) for direct stimulation of the atrial (410), A sensor (130) for sensing the ventricular activity of the heart corresponding to the direct stimulation of the atrium, A leadless pacing device (100) equipped with the following.

2. The device is further configured to determine, at least in part, the occurrence or absence of a ventricular event corresponding to the direct stimulation (410) of the atrium (A), based on the sensed ventricular activity. The leadless pacing device according to claim 1.

3. The device is configured to determine whether a direct stimulus at a predetermined stimulation power and / or predetermined stimulation energy leads to a corresponding ventricular event. The leadless pacing device according to claim 1.

4. The device is further configured to modify the stimulation power and / or stimulation energy of the direct stimulation. The leadless pacing device according to claim 1.

5. The device is further configured to perform a number of direct stimuli with different stimuli powers and / or different stimuli energies in order to determine the threshold of the stimuli power and / or stimuli energy at which a ventricular event occurs. The leadless pacing device according to claim 3.

6. The device is further configured to sense the ventricular activity and / or determine the ventricular event within a predetermined time window (420) after the direct stimulation (410). The leadless pacing device according to claim 1.

7. The device is further configured to determine at least one parameter of the time window (420) based at least in part on data stored by the device relating to time intervals measured prior to at least one of the hearts. The leadless pacing device according to claim 6.

8. The device is further configured to determine at least one parameter of the time window (420) based at least in part on performing a test stimulus with test stimulus power and / or test stimulus energy and sensing the corresponding ventricular activity. The leadless pacing device according to claim 6.

9. The sensor (130) is configured for long-distance field sensing. The leadless pacing device according to claim 1.

10. The sensor (130) is configured to receive information about ventricular activity from at least one additional first sensor (200) to be implanted in the ventricle (V) of the heart. The leadless pacing device according to claim 1.

11. The leadless pacing device (100) and, The at least one first additional sensor (200) according to claim 10, A system (S) equipped with the following features.

12. The leadless pacing device (100) includes a second additional sensor (150) for directly sensing the atrial activity of the heart corresponding to the direct stimulation (410) of the atrium (A). A leadless pacing device (100) according to any one of claims 1 to 10.

13. A method (300) for determining the stimulus response performed by a leadless pacing device (100) implanted in the atrium (A) of the heart, wherein the method (300) Step (310) of performing direct stimulation (410) of the atrium of the heart by the device at a predetermined stimulation power and / or predetermined stimulation energy, The steps include (320) sensing the ventricular activity of the heart corresponding to the direct stimulation by the device, The steps include determining whether a ventricular event corresponding to the direct stimulus occurs or does not occur (330), A method including (300).

14. The method (300) further includes the step (340) of performing a number of direct stimuli with different stimuli powers and / or different stimuli energies in order to determine the threshold of stimuli power and / or stimuli energy at which a ventricular event occurs. The method according to claim 13 (300).

15. A computer program including an instruction, wherein when the instruction is executed by a computer, the instruction carries out the method according to claim 13 or 14. Computer program.

Images