Patent Application
20250018202
The present invention is generally directed to a pacemaker for a patient's heart and an operation method of such pacemaker, a respective computer program product and computer readable data carrier.
A pacemaker (or artificial pacemaker) for a patient's heart is a medical device that generates electrical pulses delivered by electrodes connected to or fixed at the pacemaker to cause the heart muscle chambers (i.e., the atria and/or the ventricles) of the patient to contract and therefore pump blood. By doing so this device replaces and/or regulates the function of the electrical conduction system of the heart. One purpose of a pacemaker is to maintain an adequate heart rate, either because the heart's natural pacemaker is not fast enough, or because there is a block in the heart's electrical conduction system. Additionally or alternatively, the pacemaker may stimulate different positions within the ventricles to improve their synchronization of the ventricles or provide defibrillation functions in order to treat life-threatening arrhythmias. Modern pacemakers are externally programmable and allow a health care provider (HCP) to select the optimal pacing mode(s) for individual patients.
A conventional pacemaker comprises a controlling and generator device comprising a processing unit and a power source external of the patient's heart and electrodes that are implanted within the heart's muscle. The electrodes are connected via leads and a header located at the device to the device. In most cases the device is implanted transcutaneous in the front of the chest in the region of the left or right shoulder. An implantable intra-cardiac pacemaker (also known as implantable leadless pacemaker—ILP), is well known miniaturized pacemaker which is entirely implanted into a heart's ventricle (V) or atrium (A) of a patient. ILPs are considered the future of cardiac pacing. Alternative or additional functions of conventional or intra-cardiac pacemakers comprise providing other electrical or electromagnetic signals to the heart or its surrounding tissue and sensing electrical or electromagnetic signals (e.g., signals from electrical depolarization fields) or other physiological parameters of the heart and/or its surrounding tissue such as the intrinsic (i.e., the heart's natural) atrial contraction or the intrinsic (i.e., the heart's natural) ventricular contraction. Due to the highly restricted size, an ILP has a small battery capacity. As a self-contained implantable device, the size of the ILP is as small as 1 cm3, and the battery volume and capacity in the leadless pacemaker is significantly lower (less than 1/10) than for the conventional pacemaker. In order to ensure the longevity of the ILP is comparable to the conventional pacemaker (around or above 10 years), it is critical to keep the current consumption of all the modules/units of the ILP minimal.
In a VDD mode, which may be used in a conventional pacemaker or in an ILP, the pacemaker synchronizes ventricular pacing with the intrinsic ventricular or atrial timing by sensing when ventricular or atrial contractions occur. The ventricular pacing—if necessary—is then calculated based on a pacing rate, wherein in an activity-based rate responsive pacing algorithm the actual pacing rate considers the current activity of the patient. Such algorithm realizes the finding that the pacing rate needs to be increased to meet the associated higher metabolic requirements if the pacemaker-dependent patient is active. Accordingly, if the patient is not active, the pacing rate needs to be decreased.
In the activity-based rate responsive algorithm of the conventional pacemaker having a motion sensor, a scaling factor, i.e., gain value, is used to convert the physical exertion signal derived from a motion signal of a motion sensor (sensing the patient's activity) into the target exertion-modulated pacing rate. The gain value is patient specific and slowly adjusted automatically over many days to ensure that the generated target rate meets the metabolic requirement of each individual patient. In the conventional pacemaker, when the auto-gain feature is enabled, this rate adaptation algorithm is running continuously, even if the device is inhibited from pacing, to ensure the scaling factor in the rate adaptation algorithm is adjusted to suit the patient's unique needs. Even if the pacemaker is not working in the physical exertion-based rate adaptation mode, the motion sensor and part of the algorithm still run to support the update of the gain value.
The present disclosure is directed toward overcoming one or more of the above-mentioned problems, though not necessarily limited to embodiments that do.
The above method causes unnecessary current consumption. In particular, an ILP which has very strict size and power consumption requirements challenges the continuous running of rate adaptation algorithm. The current consumption of the motion sensor and the rate adaptation algorithm has a significant impact on the lifetime. Further, the known method is susceptible to random noise in the activity level. If there is an unexpected or abnormal day with extremely low or high activity, i.e., random noise, the auto-gain value will be adjusted accordingly. And in the following day(s), the gain value corresponding to the abnormal noise will be applied in the rate adaptation algorithm, until the gain value is re-adjusted.
Accordingly, there is the need for a pacemaker which provides activity-based pacing but works with low power consumption.
At least the above problem is solved with a pacemaker comprising the features of claim 1 and an operation method comprising the features of claim 8 as well as with a computer program product comprising the features of claim 14 and a computer readable data carrier comprising the features of claim 15.
In particular, a pacemaker for a patient's heart is disclosed comprising a processing unit, a detector and a pacing signal generator, wherein the processing unit, the detector and the pacing signal generator are electrically interconnected. The detector is configured to determine activity signals of the patient and to transmit or provide the activity signals to the processing unit. The processing unit is configured to determine a pacing rate based on the currently received activity signals of the detector and on a gain value in an adaption mode or in a stabilized mode, wherein the processing unit is configured to produce a pace control signal based on the determined pacing rate and to transmit or provide it to the pacing signal generator. In the adaption mode the processing unit is configured to continuously or stepwise adapt the gain value to the specific patient, wherein the processing unit is configured to stay in the adaption mode as long as at least one stability criterion is not met and to transition in the stabilized mode if the processing unit identifies that the at least one stability criterion is met. In the stabilized mode the processing unit is configured to use a locked gain value determined based on the most recently adapted gain values for determining the pacing rate.
The processing unit processes signal data received from the detector, for example activity signals which are detected over time. From these signals, the processing unit may determine a motion signal which is explained in detail below.
The pacemaker may be a conventional cardiac pacemaker or an ILP having the general structure as indicated above.
The ILP or the conventional pacemaker may be operated in VDD pacing mode (i.e., a pacing mode in which the ventricle is stimulated according to atrial activity and AV conduction monitoring). In the VDD mode, the pacemaker synchronizes ventricular pacing with the intrinsic atrial timing by sensing when atrial contractions occur. In an ILP that is implanted in the right ventricle, the atrial contraction information can be detected as a far field signal, but with less reliability and accuracy than in a dual chamber pacemaker where there is a lead in the right atrium as well as the right ventricle. In the VDD mode, since there are no atrial paces, the pacemaker is completely reliant on synchronizing to the cardiac conditions rather than being able to control the timing in both chambers as can be done in the DDD pacing mode (in which the atrium and ventricle are paced). The processing unit may be configured to detect an atrial sense event (i.e., a sensed natural atrial contraction) and/or a ventricular sense event (i.e., a sensed natural ventricular contraction), for example by the detector which may be configured to sense electrical and/or electromagnetic signals, e.g., signals from electrical depolarization fields.
With regard to the present invention the processing unit is generally regarded as a functional unit of the pacemaker, that interprets and executes instructions comprising an instruction control unit and an arithmetic and logic unit. The processing unit may comprise a microprocessor, a controller, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field-programmable gate array (FPGA), discrete logic circuitry or any combination thereof. Further, the processing unit may comprise a counter and a clock. The counter may be used to count clock signals of the clock. The counter may be started at each sensed atrial or ventricular event and count the number of clock signals until a ventricular sense event is determined or a ventricular pace signal is provided by the pacing signal generator. The actual pacing rate determined by the processing unit is used to provide a pacing control signal (e.g., the ventricular pace control signal) to the pacing signal generator. It is calculated using the last sensed atrial or ventricular event or the last atrial or ventricular pacing control signal, wherein it may use the clock signals counted by the counter.
Based on the pacing control signal the pacing signal generator produces the electrical pacing signal(s) in order to transfer it to the electrodes which apply the signal(s) to the heart's tissue adjacent to the electrode.
The pacemaker may comprise a data memory which may include any volatile, non-volatile, magnetic, or electrical media, such as a random access memory (RAM), read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasable programmable ROM (EEPROM), flash memory, or any other memory device.
The detector comprises an accelerometer, a vibration sensor, an acoustic sensor (including ultrasound) and/or any other mechanical, electric and/or magnetic sensor that is capable to detect the activity of the patient dependent on time (i.e., a motion sensor), e.g., whether the patient moves or moves not, for example lies, sleeps, sits, moves fast or slowly, including exercising. The detector collects the activity signals of the patient and transforms them into electrical signals. Further, the detector may digitize analog signals or smooth them. Some pre-processing steps may be provided by the detector, as well. The time dependent activity signals produced by the detector may be transmitted to the processing unit directly or after a pre-defined time delay. Further, the detector may comprise means to detect ECG signals as indicated above.
The pacing signal generator produces the pacing signals which are then applied via the electrodes to the heart's tissue. The pacing signals are pulses that begin at a desired time point and have a desired intensity and length. Further, the pulse form may be varied. Information on the pacing signals that are necessary to produce the correct pacing signals are provided by the pace control signal of processing unit.
The pacemaker may comprise further modules such as a communication unit for communication with a remote computer and a power supply such as a battery. The communication unit may exchange messages with the external (at least partially extracorporeally) remote computer, for example in one single direction or bidirectionally. The communication may be provided wirelessly via the patient's body and/or the air using electromagnetic waves, for example Bluetooth, WLAN, ZigBee, NFC, Wibree or WiMAX in the radio frequency region, or IrDA or free-space optical communication (FSO) in the infrared or optical frequency region or by wire (electrical and/or optical communication). The remote computer is a functional unit that can perform substantial computations, including numerous arithmetic operations and logic operations without human intervention, such as, for example, a personal mobile device (PMD), a desktop computer, a server computer, clusters/warehouse scale computer or embedded system. The pacemaker's units and components may be contained within a hermetically sealed housing.
In one embodiment the pacemaker comprises electrodes for application of an electrical pacing signal provided by the pacing signal generator. The electrodes are electrically connected to the pacing signal generator via a header of the pacemaker. In one embodiment (i.e., in the case in which the pacemaker is a conventional pacemaker) the electrode may comprise a lead which may be detachably connected to the respective connector at the header. With regard to an ILP one electrode may be located at a distal end of the ILP, close to a fixation member by which the ILP is fixed in the tissue of the patient's heart, for example within the inner tissue of a ventricle. A second electrode may be located at the proximal end of the ILP or a part of the ILP housing that may, for example, serve as counter electrode. Further, the electrodes may be adapted to detect intrinsic ventricular signals or intrinsic atrial signals by picking up electrical potentials. The electrodes may thereby be part of the detector of the pacemaker.
According to the present invention the processing unit of a pacemaker that operates, for example, in a VDD mode, is configured to determine a pacing rate based on the currently received time dependent activity signals of the detector, e.g., raw accelerometer signals provided by the detector as indicated above, and on a gain value. The gain value is a scaling factor that is used as a slope to convert a motion signal derived from the activity signals of the detector into the pacing rate which is thereby adapted to be suitable for the currently sensed activity of the patient. The amplitude of the activity signals over time are first compared with an activity threshold by the processing unit. Only the activities above motion threshold are used to calculate the pacing rate. If the activities are below motion threshold, the pacing rate will not be updated, and the gain value will not be affected. In the next step an integral of the activity signals above the threshold over a pre-determined time period (in the following integration time period), e.g., over 1 second or 1 minute, is calculated, wherein the integral is the motion signal mentioned above. If the activities are below the motion threshold, they signal will not be integrated, and the pacing rate will not be updated. Then, a scaled activity value is derived from the motion signal wherein the motion signal is multiplied by a first component of the gain value (slope) and this product may be added to a second component of the gain value (offset), if applicable. The so calculated scaled activity value is added to a pre-determined basic pacing rate to obtain the activity-based pacing rate for the patient. As indicated above the gain value may comprise two components, namely a slope value and an offset value. Alternatively, the gain value may comprise the slope value only and/or one value for each activity direction of the 3-dimensional space thereby calculating the scaled activity for each direction in space separately. As a further alternative, the gain value may be determined for different time period types, for example a resting day, an exercise day, a sleeping time period, or an active time period. The final value of the scaled activity is the absolute value over the 3 dimensions. In case of different types of time period, the scaled activity is calculated for each type of time period separately. The determined scaled activity is then used to determine the activity-based pacing rate as indicated above. Accordingly, the gain value may be a 1-dimensional or a multi-dimensional value. Further, the gain value may have one component (the slope only) or two components (slope and offset) for each gain value dimension.
During the adaption mode the gain value is continuously or stepwise adapted to the specific patient by the processing unit using the above calculation and based on the below explanation.
In one embodiment the stability criterion is met if an absolute value of a difference of a first average value of the adapted gain values determined within a first time period (in the following also referred to as first window) and a second average value of the adapted gain values determined within a second or the next time period (in the following also referred to as second window) is less than a pre-determined stability threshold value. This means that the stability criterion assesses the delta between the first average value of gain values and the second average values of gain values between two adjacent windows. Therein, in one embodiment the first time period and the second time period are directly adjacent, most recently assessed time periods. The first time period and the second time period may be several hours, one day or several days and may cover a plurality of integration time periods mentioned above. The length of the first time period and the second time period may be identical. The average value may be an arithmetic, geometric or harmonic mean or median value of the gain values determined within the first window or the second window, respectively. Alternatively or additionally, the stability criterion may be met if the pacing rate is updated in the adaptation mode for a pre-defined adaption time period, for example, 60 days. The pre-programmed or user-adaptable (e.g., by a programmer) adaption time period is long enough in order to allow full adaption of the gain value and may cover a plurality of integration time periods. In one embodiment, both stability criteria may continuously be checked and the transition into the stabilized mode is provided by the processing unit if one of both criteria is fulfilled.
In detail, in the adaption mode which is the initial mode after a conventional pacemaker is implanted, the gain value is set to a pre-defined initial value. For safety considerations, in order to avoid pacing at an excessively high rate, the initial value of gain is close to the lowest setting. When the rate adaptation algorithm is running in the adaption mode, the pacing rate is calculated using the activity signal and the actual gain value as indicated above. Accordingly, in the adaption mode the target pacing rate and the gain value are adapted simultaneously. The statistics of the pacing rate are calculated and used to adjust the gain value automatically for every pre-defined time period, for example, every day. Therein, in one embodiment, the duration counter is used to record the duration when the activity rate is above the pre-defined maximum rate threshold. This means the patient's pacing rate is high and can meet the increased metabolic requirement for the period of duration counter. In the balanced scenario, the duration counter should be within a pre-defined range, for example, 30 minutes to 60 minutes each day. If the duration counter is below the pre-defined balance (pacing rate above the maximum rate threshold for too short), the gain is too low and need to be incremented one or more setting steps. On the other hand, if the duration counter is above the pre-defined balance (pacing rate above the maximum rate threshold for too long), the gain is too high and need to be decremented by one or more setting steps. The goal of the adjustment is to make sure the distribution of the pacing rate over a certain period meets a defined balance, a.k.a., a pre-defined rate balance of the duration counter.
If the above explained stability criterion is reached, i.e., the processing unit has indicated that the average gain value is stabilized, for example as described above, the processing unit enters the stabilized mode in which the locked gain value is used to determine the pacing rate from the activity signals provided by the detector. In the stabilized mode the locked gain value may be the most recently determined average gain value (calculated in the adaption mode). In the stability mode the gain value is not changed.
In one embodiment, in the stabilized mode the processing unit is configured to interrupt or reduce detecting the activity signals by the detector, wherein the processing unit is configured to determine the motion signal from the reduced activity signals. For example, the activity signals are determined less frequently by the detector, for example each second minute only. Further, if the activity-based algorithm is currently not used in the pacemaker, the detection of the activity signals by the detector is interrupted. This may be set by a programmer.
In one embodiment, the processing unit transitions from the stabilized mode into the adaption mode if the processing unit receives a respective request, for example by a programmer, and/or if a pre-defined third time period, for example 6 months, is expired since the transition into the stabilized mode. The operation of the adaption mode (after return in this mode) is similar to the first use of the adaption mode after implantation of the pacemaker. However, in this case, as an initial gain value for the adaption mode the locked gain value is used.
The above problem is further solved by an operation method of a cardiac pacemaker, wherein the pacemaker comprises a processing unit, a detector and a pacing signal generator, wherein the processing unit, the detector and the pacing signal generator are electrically interconnected, wherein activity signals of the patient are determined by the detector and transmitted to the processing unit, wherein a pacing rate is determined by the processing unit based on the current activity signals of the detector and based on a gain value in an adaption mode or in a stabilized mode, wherein a pace control signal is produced by the processing unit based on the determined pacing rate and transmitted to the pacing signal generator, wherein in the adaption mode the gain value is continuously or stepwise adapted to the specific patient, wherein the processing unit stays in the adaption mode as long as at least one stability criterion is not met and transitions in the stabilized mode if the processing unit identifies that the at least one stability criterion is met, wherein in the stabilized mode the processing unit uses a locked gain value determined based on the most recently adapted gain values for determining the pacing rate.
As indicated above, the gain value may be a 1-dimensional or multidimensional value, and may have one component or two components.
In one embodiment of the operation method, the stability criterion is met if an absolute value of a difference of a first average value of the adapted gain values determined within a first time period and a second average value of the adapted gain values determined within a second time period is less than a pre-determined stability threshold value, wherein the first time period and the second time period may be directly adjacent, most recently assessed time periods.
In one embodiment, in the stabilized mode detection of the activity signals by the detector are interrupted or reduced by the processing unit, wherein the processing unit determines a motion signal as indicated above from the reduced activity signal.
In one embodiment, as described above, a transition from the stabilized mode into the adaption mode is provided by the processing unit if the processing unit receives a respective request and/or if a pre-defined third time period, e.g., 6 months, is expired since the transition into the stabilized mode.
The above embodiments of the operation method have the same advantages as the above pacemaker. Embodiments of the pacemaker indicated above may be realized in the operation method analogously. It is referred to the above explanation of the pacemaker in this regard.
The above method is, for example, realized as a computer program which comprises instructions which, when executed, cause the processing unit (processor) to perform the steps of the above method (to be executed by the pacemaker, in particular at its processor) which is a combination of above and below specified computer instructions and data definitions that enable computer hardware to perform computational or control functions or which is a syntactic unit that conforms to the rules of a particular programming language and that is composed of declarations and statements or instructions needed for a above and below specified function, task, or problem solution.
Furthermore, a computer program product is disclosed comprising instructions which, when executed by the processing unit, cause the processing unit to perform the steps of the above defined method. Accordingly, a computer readable data carrier storing such computer program product is disclosed.
In this disclosure, an automatic locking method is proposed for the gain value to meet the tight current consumption requirement and still support the automatic adaption of the gain value. Typically, in the adaption mode the gain value will be stabilized after the adaptation algorithm runs for a long enough period. Unless there is a significant change of the activity level after this period, the gain value remains stable with small variations. A method to lock the adapted gain value into the stable value is proposed. By doing this, it is not necessary to run the detector and the adaptation algorithm in the background continuously, thus the longevity of the pacemaker can be extended.
Additional features, aspects, objects, advantages, and possible applications of the present disclosure will become apparent from a study of the exemplary embodiments and examples described below, in combination with the Figures and the appended claims.
The present invention will now be described in further detail with reference to the accompanying schematic drawing, wherein
In the following the embodiment of the present invention refers to an ILP type pacemaker. However, the present invention may analogously be realized in a conventional pacemaker, as well.
The processing unit 120 may communicate with pacing signal generator 124 and detector 126 thereby transmitting signals. Pacing signal generator 124 and detector 126 are electrically coupled to electrodes 111, 112 of the ILP 10. Detector 126 is configured to monitor signals from electrodes 111, 112 in order to monitor electrical activity of heart 20. Further, the detector 126 comprises a motion sensor which may include an accelerometer, an acoustic sensor and/or a pressure sensor. Pacing signal generator 124 is configured to deliver electrical stimulation signals to ventricle 21 via electrodes 111, 112.
ILP 10 may include a housing, fixation tines, and the electrodes 111, 112. The housing may have a pill-shaped cylindrical form factor in some examples. Fixation tines are configured to connect (e.g., anchor) ILP 10 to heart 20. Fixation tines may be fabricated from a shape memory material, such as Nitinol. In some examples, fixation tines may connect ILP 10 to heart 20 within one of the chambers of heart 20. For example, as illustrated and described herein with respect to
The communication unit 128 may enable ILP 10 to communicate with other electronic devices, such as a programmer or other external patient monitor. In some examples, the housing may house an antenna for wireless communication. Housing may also include the power source 132.
ILP 10 may include two electrodes 111, 112, although more than two electrodes may be included on a pacemaker in other examples. Electrodes 111, 112 may be spaced apart a sufficient distance to be able to detect various electrical signals generated by the heart 20, such as P-waves generated by atria and QRS complex generated by ventricles. The housing houses electronic components of ILP 10. Electronic components may include any discrete and/or integrated electronic circuit components that implement analog and/or digital circuits capable of producing the functions attributed to ILP 10 described above.
Processing unit 120 may control pacing signal generator 124 to generate and deliver electrical stimulation to ventricle 21 via electrodes 111, 112. Electrical stimulation may include pacing pulses. Processing unit 120 may control pacing signal generator 124 to deliver electrical stimulation therapy according to one or more therapy programs including pacing parameters, which may be stored in data memory 122.
Detector 126 may include circuits that acquire electrical signals (e.g., electric depolarization signals) from the heart including intrinsic cardiac signals, such as intrinsic ventricular signals and/or intrinsic atrial signals. Further, the detector 126 comprises an accelerometer as a motion sensor for determining activity signals of the patient 30 over time. Detector 126 may filter, amplify, and digitize the acquired electrical signals to generate raw digital data.
Processing unit 120 may receive the time-dependent digitized data generated by detector 126, in particular the digitized activity signals provided by detector 126. From the activity signals the processing unit 120 determines a pacing rate if the ILP 10 is in the activity-based rate responsive pacing mode which may be set by the programmer. In the activity-based rate responsive pacing mode the processing unit 120 may work in two different modes, namely in the adaption mode and in the stabilized mode. This is explained in the following with reference to the flowchart depicted in
Processing unit 120 may assess the raw accelerometer signals (activity signals) received from the detector 126 and is configured to set the gain value to a pre-defined initial value which is close to the lowest setting and stored in the data memory 122 after the ILP 10 is implanted (see step 201 in
In the proposed adaption mode, when the above explained pacing rate and gain value adaptation algorithm is running, the average value of the gain values is calculated from user-defined (or programmable) window size and tracked (see step 203 in
If the delta is equal to or bigger than the stability threshold value (see step 205 in
In addition, the stability of the locked gain value may be checked and updated at regular intervals, for example, every 6 months, or per the request of the patient. The update of the locked gain value is similar to the initial adaption and locking of the gain value. The only difference is that in the update procedure, the initial gain value is the previously locked value instead of initial gain value. This means that the algorithm is restarted with step 202 of
The processing unit 120 continuously determines a pacing control signal, for example for ventricular pacing, in the activity-based rate responsive pacing algorithm based on the pacing rate calculated using the actual gain value (in the adaption mode) or using the locked gain value (in the stabilized mode) based on the activity signal received from the detector 126 as explained above. The pacing control signal is transmitted to the pacing signal generator 124 which produces the corresponding electrical pacing pulses which will then applied by the electrodes 111, 112 to the patient's heart 20, for example the right ventricle 21.
The gain value is locked in the stabilized mode and the rate adaptation can be turned off so that the current budget of ILP 10 is met.
In order to ensure the locked gain value can represent the appropriate gain value corresponding to the activity level of the patient, the variability of the gain value after the transition into the stabilized mode was analyzed using the data from VVIR traditional pacemakers. The example is shown in
The above described inventive pacemaker and operation method may further be described by the following general features:
The above described pacemaker and operation method realize the following advantages:
It will be apparent to those skilled in the art that numerous modifications and variations of the described examples and embodiments are possible in light of the above teachings of the disclosure. The disclosed examples and embodiments are presented for purposes of illustration only. Other alternate embodiments may include some or all of the features disclosed herein. Therefore, it is the intent to cover all such modifications and alternate embodiments as may come within the true scope of this invention, which is to be given the full breadth thereof. Additionally, the disclosure of a range of values is a disclosure of every numerical value within that range, including the end points.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21212413.5 | Dec 2021 | EP | regional |
This application is the United States National Phase under 35 U.S.C. § 371 of PCT International Patent Application No. PCT/EP2022/082967, filed on Nov. 23, 2022, which claims the benefit of European Patent Application No. 21212413.5, filed on Dec. 6, 2021, and U.S. Provisional Patent Application No. 63/282,220, filed on Nov. 23, 2021, the disclosures of which are hereby incorporated by reference herein in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2022/082967 | 11/23/2022 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 63282220 | Nov 2021 | US |
