WO2024056250A1

WO2024056250A1 - An active implantable medical device enabling an improved battery management

Info

Publication number: WO2024056250A1
Application number: PCT/EP2023/070317
Authority: WO
Inventors: Pamela Shamsie Victoria Riahi; David Mcintosh; Andrew B. Kibler
Original assignee: Biotronik Se & Co. Kg
Priority date: 2022-09-13
Filing date: 2023-07-21
Publication date: 2024-03-21

Abstract

The invention relates to an active implantable medical device (1) comprising a battery (2); a first processor (3); and a first memory unit (4), wherein the first memory (4) unit comprises first computer-readable code that causes the first processor (3) to perform the following steps when executed on the first processor (3): sensing battery-related data (9); storing the battery- related data (9) in the first memory unit (4); transferring the stored battery-related data (9) to a remote entity (10; 11) to enable an evaluation of the transferred battery-related data (9) to detect events in the battery or charging behavior of the active implantable medical device (1).

Description

AN ACTIVE IMPLANTABLE MEDICAL DEVICE ENABLING AN IMPROVED BATTERY MANAGEMENT

The present invention relates to active implantable medical devices, in particular to the battery management of such active implantable medical devices.

The battery status and use of implanted medical devices (both rechargeable and non- rechargeable) has a significant impact on the patient’s experience with the product, especially when it performs unexpectedly. Unexpected battery behavior can include abnormally fast discharge rate, abnormal charging rate, frequent charging session interruptions due to overheating or charger misalignments, and/or battery level reaching low power threshold at which therapy stops. For example, charging frequency and ease of battery charging are direct impacts on a patient’s life that can be affected by technical and usability factors. Currently, battery behavior assessment in most implanted device is not monitored throughout product use.

Regardless whether the origin of the unexpected event of battery or charging behavior is technically or usability related, it is important to address it as soon as possible to prevent diminished positive experience by the patient. Currently, there are no known solutions in the implantable medical device field to proactively detect issues before they are reported by patients or medical teams.

Current direct reporting by patients or their medical team typically means that the product experience was negative enough to bring them to notify the product manufacturer, and that there will have been a significant amount of time between when they first experienced the issue and when the issue will be fixed, further affecting their product experience negatively. Currently, there is no way to proactively address issues before they are reported. It is furthermore of general interest for medical device manufacturers and medical device users to be provided with long term data of battery status changes and battery usage. The data can be used for identifying trends, conducting error analysis or implementing preventive measures.

It is an object of the present invention to provide an active implantable medical device enabling an improved battery remote care scheme.

This object is achieved with an active implantable medical device that comprises a battery, a first processor and a first memory unit. The first memory unit comprises first computer- readable code that causes the first processor to perform the steps explained in the following when executed on the first processor. First, battery-related data is sensed. Afterwards, the battery-related data is stored in the first memory unit. Afterwards, the stored battery-related data is transferred to a remote entity to enable an evaluation of the transferred battery-related data to monitor events in the battery or charging behavior of the active implantable medical device. Based on such detection of events in the battery or charging behavior, the battery management of the active implantable medical device can be adjusted, in particular automatically adjusted.

The presently claimed active implantable medical device allows to remotely track relevant battery data almost in real time. This allows proactive actions to mitigate potential technical or usability challenges before they are even reported by the patient carrying the active implantable medical device or by medical staff assisting the patient in using the active implantable medical device. In addition, the presently claimed active implantable medical device enables troubleshooting without systematically requiring a physical displacement of patients. The transfer of battery-related data allows an early identification of suspect issues and a quick action to address them. Training of the patient in correctly using the active implantable medical device and a charging device used for charging the battery of the active implantable medical device can then take place. Additionally or alternatively, specific charging aid hardware may be provided. Additionally or alternatively, hardware or hardware parts may be replaced in reaction of an evaluation of the provided battery -related data. According to an embodiment, monitoring events in the battery or charging behavior are used to detect unexpected events, to establish baseline behaviors, analyzing trends over time, changes in trends, analyzing battery usage and charging usage of the user (charging/discharging trends, timing, efficiency), analyzing battery performance, and/or feeding statistical models for future predictions.

The term “active implantable medical device” is well known to a person skilled in the art. An “active medical device” is typically defined to be any medical device relying for its functioning on a source of electrical energy or any source of power; That energy can be, in case of energy scavenging active implantable medical devices, be taken from human body physiological sources (movement of heart e.g.).

An “active implantable medical device” is typically defined to be any active medical device which is intended to be totally or partially introduced, surgically or medically, into the human body or by medical intervention into a natural orifice, and which is intended to remain after the procedure.

Further details on active implantable medical devices can be found, e.g., in the consolidated text of the Council Directive 90/385/EEC of 20 June 1990 on the approximation of the laws of the Member States relating to active implantable medical devices with subsequent amendments in the version published on 11 October 2007. The consolidated text of this Council Directive is freely accessible under the following link: https://eur- lex.europa.eu/legal-content/EN/TXT/?uri⁼CELEX:01990L0385-20071011

In an embodiment, the active implantable medical device is an implantable pulse generator (IPG), an implantable cardioverter-defibrillator (ICD), a device for cardiac resynchronization therapy (CRT), an implantable cardiac monitor, or a neuronal stimulator such as a spinal cord stimulator (SCS). An appropriate cardiac monitor is a loop recorder.

In an embodiment, the remote entity comprises at least one of a remote computer such as cloud-computing device, a remote service center computer that is designed and arranged for evaluating the provided data or another remote or external device which uses wireless communication means to exchange data with the implantable medical device. According to preferred embodiments, the remote entity is a patient remote device or a charger device.

In an embodiment, the remote entity is a communications unit that is more closely located to the active implantable medical device than a cloud-computing device or a remote service center computer is located. Then, the communications unit serves for transferring the received data itself to the remote computer to enable the evaluation of the transferred battery- related data. A transfer of the battery-related data from the active implantable medical device to such a communications unit can be typically easier accomplished than a direct transfer of the battery-related data to a remote computer, since the distance to be bridged for data transfer is typically shorter in case of transferrin the date to a communications unit. In an embodiment, the communications unit can also be denoted as intermediate device and can be realized in form of a telemetry relay or of an application residing on a consumer device like a patient remote application residing on a consumer phone.

In an embodiment, the battery-related data is time-stamped data.

According to the inventive active implantable medical device, the battery-related data comprises a battery status and/or a battery voltage and/or a temperature of a portion of a housing of the active implantable medical device, a temperature proximal to the portion of a housing, or a temperature proximal to the battery of the active implantable medical device and/or a battery charge rate and/or a battery discharge rate and/or a battery charge counter reading and/or a battery thermal event counter reading and/or a battery charging-related event and/or an average battery charging time and/or an average battery charging interval and/or a number of battery charging cycles in a predefinable time period and/or a battery status counter reading and/or data indicative for an alignment between the battery and a charging device during the charging process.

In an embodiment, the battery status includes the state of charge level of the battery. In an embodiment, the battery charge counter reading indicates the amount of charging events of the battery. In an embodiment, the battery thermal event counter reading indicates the amount of overheating events (temperature exceeding a predeterminable level or threshold temperature). In an embodiment, the battery thermal event counter reading includes a value of the cumulated equivalent minutes at 43 °C (CEM43), i.e., a temporal measure of the exposure of the battery to excessive heat. In an embodiment, the battery thermal event counter reading includes an indicator for exceeding another predefinable temperature limit. All of the precedingly mentioned embodiments can be combined in any desired way.

In an embodiment, the number of battery charging cycles in a predefinable time period refers to the overall time since the active implantable medical device was put in service as time period. In another embodiment, the time period indicates how many charging cycles were used to calculate the average charging time and/or the average charging interval.

In an embodiment, the battery status counter reading indicates the number of times a low battery state of charge threshold has been exceeded by the active implantable medical device. In an embodiment, the battery status counter reading indicates a number of times a different battery parameter threshold was reached or exceeded, such as a full battery power threshold.

In an embodiment, the battery is a rechargeable battery. Then, most or all of the precedingly mentioned battery -related data parameters can be used. In another embodiment, the battery is a non-rechargeable battery. Then, only some of the precedingly mentioned battery-related data parameters can be sensed and used to detect an event in the battery or charging behavior. To give an example, if the battery is a non-rechargeable battery, no battery charge counter reading and no battery charge rate can be sensed and evaluated for detecting an unexpected event in the battery or charging behavior.

In an embodiment, the first computer-readable code causes the first processor to transfer the stored battery-related data to the remote entity in predeterminable time intervals. In an embodiment, the predeterminable time intervals are chosen from every 10 minutes to once in 2 weeks, in particular from every 20 minutes to once in 10 days, in particular from every 30 minutes to once in a week, in particular from hourly to once in 3 days, in particular from every 2 hours to once a day, in particular from once in 6 hours to twice daily. In doing so, a regular data basis is provided that can be used for identifying an event in the battery or charging behavior.

In an embodiment, the first computer-readable code causes the first processor to transfer the stored battery-related data to the remote entity in an event-triggered manner. Such an event- triggered data transfer typically reduces the number of total data transfers and therefore the electric power necessary for accomplishing this data transfer.

In an embodiment, an event that triggers the event-triggered transfer of the stored battery- related data to the remote computer is a low battery status, an abnormal battery charge duration, a misalignment between the battery and a charging device, a number of occurrences of a misalignment between the battery and a charging device, a temperature of a portion of the housing, a temperature proximal to the portion of a housing, or a temperature proximal to the battery of the active implantable medical device exceeding a predeterminable threshold, a detected hardware fault of the active implantable medical device, and/or start or completion of a charging session, abort of a charging session, change of a charging rate.

In an embodiment, the low battery status is determined if a remaining power capacity of the battery is below a predeterminable threshold. In an embodiment, an abnormal battery charge duration is determined if the charge duration of the battery exceeds a predeterminable threshold.

In an embodiment, the first computer-readable code causes the first processor to automatically identify a misalignment between the battery and a charging device if at least one of the following events is detected.

The first event is fulfilled if a number of increase and decrease events of power provided to the battery during the charging cycle exceeds a predeterminable threshold. A high number of unexpected increase and decrease of power events is indicative for an improper alignment between battery and charging device or for a relative movement between battery and charging device. Typically, one would expect that an essentially constant power is provided by the charging device to the battery during the charging cycle. According to an embodiment, specific metrics are established for measuring the number and extent of misalignments have occurred in a charging session. For instance charging sessions with up to three misalignments can be classified as “micro misalignment event”, wherein charging sessions with more than 3 misalignments can be classified as “medium misalignment event”. As example, the first event is fulfilled if a “medium misalignment event” was detected, wherein a “micro misalignment event” only leads to a note in the charging monitoring data.

The second event is fulfilled if the rate of increase of the temperature of the housing of the active implantable medical device exceeds a predeterminable threshold. Such temperature increase of the housing is indicative for an insufficient energy transfer into the battery, while a comparatively high amount of energy is provided from an external source (like the charging device). In such a case, the energy provided by the charging device is not stored as electric energy within the battery of the active implantable medical device, but is rather converted into thermal energy leading to a temperature increase of the active implantable medical device and therewith of the housing of the active implantable medical device.

The third event is fulfilled if a slope or morphology of a curve representing a rate of increase of the temperature of the housing of the active implantable medical device deviates from a predeterminable standard configuration by an amount exceeding a predeterminable threshold. While one typically expects a certain temperature increase during a battery charging process, a particularly high slope or unexpected subsequent events of increasing and decreasing temperature indicate a misalignment between a charging device and the battery.

The fourth event is fulfilled if the charging current is lower than a predeterminable threshold. At a given power of the charging device, one would expect a certain charging current provided to the battery of the active implantable medical device. If, however, the charging current is below the expected value, this indicates that a significant part of the power provided by the charging device does not reach the battery of the active implantable medical device. In an aspect, the present invention relates to an arrangement comprising a charging device, a patient remote device or another external device, and an active implantable medical device according to the preceding explanations.

In an embodiment, the first computer-readable code causes the first processor to transfer the stored battery-related data to the charging device, the patient remote device or another external device. Thus, in this embodiment, the charging device serves as remote entity. However, the charging device typically does not evaluate the battery-related data itself. Rather, it transfers this battery -related data to a remote evaluation computer.

In an embodiment, the charging device, the patient remote device or the other external device comprises a second processor and a second memory unit. In this context, the second memory unit comprises second computer-readable code that causes the second processor to perform the steps explained in the following when executed on the second processor.

In one method step, the battery-related data is received from the active implantable medical device. In another method step, additional charging-related data is sensed by the charging device, the patient remote device or the other external device. In an optional step, the received battery-related data and/or the additional charging-related data is stored in the second memory unit. In a further method step, the received battery-related data is transferred together with the additional charging-related data to a remote computer for evaluating the battery-related data and the charging-related data. This data transfer can be done directly (via a direct data connection between the charging device, the patient remote device or the other external device, and the remote computer) or indirectly (e.g., via a communications unit, as explained above for the active implantable medical device).

In an embodiment, the charging device, the patient remote device or the other external device comprises a second processor and a second memory unit, wherein the second memory unit comprises second computer-readable code that causes the second processor to perform the steps explained in the following when executed on the second processor. According to one step, additional charging-related data is sensed. According to an optional step, the additional charging-related data is stored in the second memory unit. In a further step, the additional charging-related data is transferred to the active implantable medical device. In this context, the first computer-readable code causes the first processor (i.e., the processor of the active implantable medical device) to receive the additional charging-related data and to transfer the stored battery -related data together with the additional charging-related data to a remote entity. Thus, it is not only possible that a data transfer is performed from the active implantable medical device to the charging device, the patient remote device or the other external device, but also in the opposite direction. While one typically may prefer transferring data over a comparatively short distance from the active implantable medical device to the charging device, the patient remote device or the other external device and to transfer the data than over a longer distance (e.g., via communications unit) to a remote entity, a different direction of data transfer is also possible. While the first possibility is particularly economical with respect to power capacity available within the active implantable medical device, the second option may require a higher amount of electric energy stored in the battery of the active implantable medical device. However, it is possible to charge the battery of the active implantable medical device during the data transfer from the charging device, the patient remote device or the other external device, to the active implantable medical device so that an additional amount of energy needed for transferring not only the battery-related data, but also the charging-related data by the active implantable medical device can be compensated or even more than compensated.

In an embodiment, the charging-related data comprises a charging status (e.g., charging/non- charging) and/or a charging device status (e.g., active, inactive, connected to an external energy source, charging device battery status etc.) and/or a charging seeking activity while the charging device is attempting to locate the active implantable medical device and/or an activation of an implant localization mode (e.g., by trying to identify a metallic element in the surroundings of the charging device by inductance) and/or a charging device battery level (e.g., high battery level, low battery level, sufficient battery level) and/or a charging device temperature (e.g., charging device temperature lying in a predeterminable range or exceeding a predeterminable threshold) and/or data on a power delivery to a charging coil of the charging device (e.g., current versus voltage phase information of the power delivered to the charging coil). Such charging-related data gives additional insight into the charging process and allows an identification of an abnormal status that needs to be remedied in order to allow proper functioning of the charging device and/or the active implantable medical device.

In an embodiment, the arrangement comprises a communications unit that serves for receiving data from the active implantable medical device and/or from the charging device, the patient remote device or the other external device, and that furthermore serves for transmitting the data to a remote computer or a remote server. The remote computer or remote server may then evaluate the data or transfer it to a different evaluating computer. As already explained above, such a communications unit may be implemented in form of an application residing on a consumer device such as a smart phone.

In an embodiment, the communications unit serves for transferring data to the remote computer in a wireless manner. All standard data transmission protocols or specifications are appropriate for such a wireless data communication. Examples of standard data transmission protocols or specifications are the Medical Device Radiocommunications Service (MICS), the Bluetooth Low Energy (BLE) protocol and the Zigbee specification.

In an embodiment, the first computer-readable code causes the first processor to transfer an alert (such as charging started/ stopped etc.) in real time to the communications unit, wherein the communications unit pushes such alert to a remote entity (such as a remote computer backend) for further processing.

In an aspect, the present invention relates to a method for improving a battery management of an active implantable medical device, in particular of an active implantable medical device according to the preceding explanations. This method comprises the steps explained in the following.

In a first step, battery-related data is received from an active implantable medical device. In an optional step, additional charging-related data is obtained from a charging device. In this context, the battery-related data and the charging-related data can be obtained in a single step from one and the same device. However, the battery-related data is generally sensed or gathered by the active implantable medical device, wherein the charging-related data is sensed or gathered by the active implantable device or the charging device.

In a further method step, the battery-related data and optionally the additional charging- related data is evaluated to identify an event in the battery or charging behavior of the active implantable medical device. If such event in the battery or charging behavior is identified, at least one of the following events is carried out. According to a first event, a user of the active implantable medical device (typically a patient) and/or of the charging device is trained in an optimized charging process (e.g., in an optimized alignment between the charging device and the active implantable medical device). Such training can be performed by videoconference or by personally instructing the user by medical staff.

According to a second event, charging aid hardware is provided to a user of the active implantable medical device and/or of the charging device. This charging aid hardware may facilitate future charging processes and allows a higher charging performance.

According to a third event, the active implantable medical device, the charging device, or parts of the active implantable medical device or of the charging device are replaced. Such a replacement is carried out if the observed event in the battery or charging behavior is obviously not due to a user fault, but rather due to a hardware fault.

In an embodiment, the evaluating of the received battery-related data and optionally of the received additional charging-related data is done automatically. In another embodiment, the evaluating is performed by using expert knowledge. To give an example, a trained member of a remote care team reviews incoming battery-related data and optionally charging-related data daily. This data may be already preprocessed by the remote entity or a different system to highlight suspicious battery behavior that needs further review. Such automatic highlighting facilitates the subsequent evaluation of the data. In an embodiment, the remote care team then decides on the action to be taken. To give some examples, the patient may be contacted directly, a remote follow-up may be scheduled, an in-office visit may be scheduled, or the detected event in the battery or charging behavior may be forwarded to another remote team. In an embodiment, the battery-related data and optionally the additional charging-related data is preprocessed by overlaying multiple simultaneous time series such as a temperature of the housing of the active implantable medical device and a battery charge rate or a battery voltage. Such overlay may facilitate the subsequent evaluation of the respective data.

In an embodiment, the battery-related data and optionally the additional charging-related data is automatically evaluated, wherein events being indicative for an event in the battery or charging behavior are automatically flagged, wherein such flagging automatically triggers a notification to an appropriate remote team depending on the type of detected event in the battery or charging behavior. To give an example, a technical team may be automatically notified in case of having identified a hardware issue, whereas a remote care team is automatically notified in case of a detected improper charger utilization.

In an embodiment, the patient is directly contacted by the evaluating entity, e.g., via a message on the patient’s remote device application or another patient’s device app (e.g. smartphone app), in case there has been detected an unexpected event in the battery or charging behavior that can be remedied, e.g., by any specific instructions to the patient (such as a request to change a charging program or a request to try a different position of the charging device).

In an embodiment, it is possible to assign customizable thresholds for notifications. To give an example, it may be the case that a particular patient still experiences moderate levels of misalignment between the charging device and the active medical implant even after having received coaching (either by the evaluating computer, by a video conference with medical staff, by a phone call from medical staff, or by personal training through medical staff). However, such moderate levels of misalignment are considered to be normal for this specific patient considering his or her capabilities. Then, the notification threshold is adjusted such that moderate levels of misalignment do not trigger any notifications. This enhances the user- friendliness of the active implantable medical device and the associated charging device. Such personalized notification threshold is, in an embodiment, assigned to the specific patient so that it will have no impact who takes care of an evaluation of the battery-related data and optionally the additional charging-related data provided by the active implantable medical device and/or the charging device of this patient.

In an embodiment, ambient temperature data is additionally evaluated to identify an event in the battery or charging behavior of the active implantable medical device. Such ambient temperature data is obtained, in an embodiment, from a remote device or an application residing on a consumer telephone or tablet in the vicinity of the patient. In an embodiment, the ambient temperature data is retrieved from a national weather database, e.g., based on the patient’s address or ZIP Code. In an embodiment, the ambient temperature data is entered on a patient remote device by the patient and telemetrically transferred to the remote entity. In an embodiment, the ambient temperature data is retrieved from the charging device used by the patient and is transferred to the remote entity. Such ambient temperature data is particularly helpful in case of the patient is located at a place without air-conditioning, but comparatively high temperatures. In surroundings having a significantly elevated ambient temperature, an overheating of the active implantable medical device may occur. If it turns out, based on the additionally provided ambient temperature data, that the ambient temperature is deemed to be a contributing factor to recharging overheating, appropriate coaching may be provided to the user of the active implantable medical device to accomplish recharging of the battery in less warm surroundings.

All embodiments of the active implantable medical device can be combined in any desired way and can be transferred either individually or in any arbitrary combination to the arrangement and/or to the method. Furthermore, all embodiments of the arrangement can be combined in any desired way and can be transferred either individually or in any arbitrary combination to the active implantable medical device and/or to the method. Finally, all embodiments of the method can be combined in any desired way and can be transferred either individually or in any arbitrary combination to the active implantable medical device and/or to the arrangement.

Further details of aspects of the present invention will be explained in the following referring to exemplary embodiments and accompanying Figures. In the Figures: Figure 1 shows a schematic depiction of an embodiment of an active implantable medical device;

Figure 2A shows an arrangement of an implantable medical device and a charging device in a first data transfer mode;

Figure 2B shows the arrangement of Figure 2A in a second data transfer mode;

Figure 3 shows a schematic depiction of a quality assessment performed during operation of an arrangement of an active implantable medical device and a charging device;

Figure 4 shows a first exemplary embodiment of a graphical representation of battery- related data;

Figure 5A shows a second exemplary embodiment of a graphical representation of battery-related data;

Figure 5B shows an enlargement of the region of the battery-related data marked with a box and a “B” in Figure 5A; and

Figure 6 shows a comparison of the temperature course during different charging sessions.

Figure 1 shows a schematic depiction of an active implantable medical device 1 that comprises a battery 2, a processor 3 and a memory unit 4. The processor 3 serves as first processor, wherein the memory unit 4 serves as first memory unit. Battery -related data of the battery 2 can be sensed upon according instructions of the processor 3 and stored in the memory unit 4. Afterwards, this battery-related data can be transferred to a remote entity, such as a remote service center computer. Figure 2A shows an arrangement 15 (also denoted as monitoring system) comprising an active implantable medical device 1 and a charger 5 that serves as charging device. In this and in all following Figures, similar elements will be denoted with the same numeral reference.

The charger 5 comprises a second processor 6 and a second memory unit 7. The charger 5 provides electrical power 8 to the active implantable medical device in a wireless conductive manner. The active implantable medical device 1 transfers battery-related data 9 to the charger 5 and to a communications unit 10. In doing so, the charger 5 is provided with relevant information on the status of the battery 2 of the active implantable medical device 1 so that it can adjust the electrical power 8 transferred to the active implantable medical device 1 in an appropriate way.

By transferring the battery-related data 9 to the communications unit 10, subsequent evaluation of this battery-related data 9 is made possible. This evaluation is performed by a remote computer 11 to which the battery-related data 9 is transferred by the communications unit 10.

The data transfer via the communications unit 10 saves energy of the active implantable medical device 1 since the communications unit 10 is located in proximity to the active implantable medical device 1. The data transfer to the remote computer 11 is powered by the communications unit 10 that can be connected to a regular power network and is thus not dependent on a limited battery capacity.

Figure 2B shows the arrangement 15 of Figure 2A in a second data transfer mode. The charger 5 provides electrical power 8 to the active implantable medical device in the same way as in the embodiment of Figure 2A. However, the active implantable medical device 1 transfers charging data 9 only to the charger 5, not to the communications unit 10. Rather, only status information 12 is transferred from the active implantable medical device 1 to the communications unit 10. The charger 5 receives the battery-related data 9 from the active implantable medical device 1. The charger 5 then adds additional charging-related data 13 to the battery-related data 9 and transfers both the battery-related data 9 and the additional charging-related data 13 to the communications unit 10. The communications unit 10 then transfers the battery -related data 9, the battery status data 12, and that the additional charging-related data 13 to the remote computer 11 for evaluating the battery behavior of the active implantable medical device 1.

In the embodiment shown in Figure 2B, the additional charging-related data comprises additional details about the charging status, the patient behavior (i.e., the ability of the patient to align the charger 5 with the active implantable medical device 1) and the status of the charger 5. The battery-related data 9 of the embodiment shown in Figures 2A and 2B comprises at least voltage data of the battery 2 and temperature data of the battery 2 or a housing of the active implantable medical device 1, respectively.

In the arrangement 15, the data quality is assessed during monitoring the battery-related data 9. A schematic depiction of this quality assessment is shown in Figure 3. The battery -related data 9 and optionally the additional charging-related data 13 is evaluated in the remote computer 11 in a first decision step 21 as to whether the data quality of the received data is acceptable. If this is the case (Y), a second decision step 22 is made. In this second decision step 22, it is checked whether the charging performance is acceptable. If this is the case (Y), the arrangement 15 proceeds to a waiting step 23 in which it waits for new data that is afterwards checked in the same manner by the first decision step 21 and the second decision step 22.

If the data quality is deemed to be not acceptable in the first decision step 21 (N), a first training step 24 is provided to the patient. This training is intended to ameliorate the handling of the charger 5 and its interaction with the active implantable medical device 1 to finally increase the data quality of the battery-related data 9 and optionally the additional charging- related data 13. If the charging performance is found to be not acceptable in the second decision step 22 (N), a training and/or support is offered to the patient in a second training step 25. This training or support offered to the patient is intended to increase the charging performance. Generally, the arrangement 15 illustrated in Figures 2A and 2B is designed to be robust against network connection issues and has the ability to charge the active implantable medical device 1 also if the communications unit 10 is not in connection with the charger 5 or the active implantable medical device 1. In such a case of disconnection, the battery - related data 9 and/or the charging-related data 13 is buffered by the active implantable medical device 1 and/or the charger 5. The first memory unit 4 and/or the second memory unit 7 are typically used for this purpose.

In the event of lost battery-related data 9 and/or charging-related data 13, the arrangement 15 is able to maintain an awareness that a lack of reconnection events or of thermal events is simply a lack of information which is to be addressed with the patient in a workflow distinct from a workflow addressing charging issues.

Figure 4 shows a plot on battery-related data, namely on a battery voltage 90 and a temperature 91 of the housing of the active implantable medical device 1 that reflects the temperature of the battery 2 of the active implantable medical device (cf. Figure 1). In this context, the left y-axis indicates the scale for the voltage 90, wherein the right y-axis indicates the scale for the temperature 91. The voltage 90 can generally range between a lower threshold 900 and an upper threshold 901. The lower threshold indicates the low- power threshold at which a recharge of the battery is required. In the embodiment shown in Figure 4, the lower threshold 900 lies at 3.67 V. The upper threshold 901 indicates the fully charged state of the battery and lies at 3.99 V.

The data shown in Figure 4 is typically displayed together with additional data, such as average charging time and interval over the past 30 days and the number of charging cycles used for this calculation, number of charging cycle in the product’ s lifetime, number of times critical battery thresholds were reached, and number of times thermal counters were reached. The data shown in Figure 4 was obtained from a spinal cord stimulation (SCS) device.

The start of a charging event is indicated by a triangle, wherein the stop of a charging event is indicated by a square. A cross indicates an unknown charge status. The charge status is unknown if no connection between the active implantable medical device 1 or the charger 5 on the one hand and the communications unit 10 on the other hand is established (cf. Figures 2A and 2B for more details). Such periods of disconnection are indicated with grey bars in Figure 4. After having re-established the connection, the charging status can be determined again on the basis of the battery-related data 9 and optionally the additional charging-related data 13 provided by the active implantable medical device 1 and/or the charger 5 to the communications unit 10 (cf. Figures 2A and 2B for more details).

Figure 5A shows a similar diagram on battery-related data like Figure 4, wherein again a battery voltage 90 and a temperature 91 of the housing of the active implantable medical device 1 is displayed. For simplification purposes, the connectivity status between the active implantable medical device 1 and the charger 5 on the one hand and the communications unit 10 on the other hand is not displayed in Figure 5 A.

In the charging session that has taken place on January 20^th, a plurality of charging start and charging stop events have been detected. The respective part of the voltage curve 90 and the temperature curve 91 is encircled by a box marked with a B. This part of the curves is depicted in Figure 5B in an enlarged view. Here, it can be seen that there were two series of consecutive charge start/stop events that suggest that the patient had difficulty in correctly aligning the charger 5 to the active implantable medical device 1 at the beginning of the session (between 19:30 hours and 20:00 hours). A thermal counter also detected four overheating events of the active implantable medical device that are deemed to be indicative for poor alignment between the charger 5 and the active implantable medical device 1.

Thus, by evaluating the battery-related data 9, a much deeper insight in the charging performance and in the patient’s capability of handling the charger 5 and the active implantable medical device 1 is gained than according to prior art solutions that do not track such data. Since the battery-related data 9 (composed in the embodiment shown in Figures 5A and 5B of voltage data 90 and temperature data 91) is transferred via the communications unit 10 to a remote computer 11 for further evaluation in almost real-time, any specific issues with the hardware of the active implantable medical device 1 and the handling of the active implantable medical device 1 and/or the charger 5 by the patient are detected without relevant delay and can be thus immediately addressed. This significantly increases the usability of the arrangement 15.

Figure 6 shows a graphical depiction of the temperature evolvement during different charging sessions on a relative timescale. In this context, the time of 0 minutes indicates the start of the charging session. Prior to perform the individual charging sessions, a “gold standard” charging session 910 was recorded for the specific patient. This gold standard charging session 910 was supported and monitored by experts. Three subsequent charging sessions 911, 912, and 913 show a temperature profile that is somewhat higher than the temperature profile of the gold standard charging session 910, but is considered to be still in an acceptable range. The fourth charging session 914, however, shows a temperature profile that exceeds the temperature profile of the gold standard charging session 910 to a significant extent and is thus considered as indicative for a misalignment between the charger 5 and the active implantable medical device 1 (cf. Figures 2A and 2B for more details).

Claims

1. An active implantable medical device (1) comprising a battery (2); a first processor (3); and a first memory unit (4), wherein the first memory (4) unit comprises first computer- readable code that causes the first processor (3) to perform the following steps when executed on the first processor (3): sensing battery-related data (9); storing the battery-related data (9) in the first memory unit (4); transferring the stored battery -related data (9) to a remote entity (10; 11) to enable an evaluation of the transferred battery-related data (9) to monitor events in the battery behavior or charging behavior of the active implantable medical device (1), wherein the battery behavior or charging behavior-related data (9) comprises at least one of a temperature (91) of a housing of the active implantable medical device or an estimate of the same, a battery charge rate, a battery discharge rate, a battery charge counter reading, a battery thermal event counter reading, a battery charging- related event, an average battery charging time, an average battery charging interval, a number of battery charging cycles in a predefinable time period, a battery status counter reading, and data indicative for an alignment between the battery and a charging device during a charging process.

2. The active implantable medical device according to claim 1, wherein the first computer-readable code causes the first processor (3) to transfer the stored battery- related data (9) to the remote entity (10; 11) in predeterminable time intervals.

3. The active implantable medical device according to claim 1, wherein the first computer-readable code causes the first processor (3) to transfer the stored battery- related data (9) to the remote entity (10; 11) in an event-triggered manner. The active implantable medical device according to claim 3, wherein an event that triggers the transfer of the stored battery -related data (9) to the remote entity (10; 11) is at least one chosen from a low battery status, an abnormal battery charge duration, a misalignment between the battery and a charging device, a number of occurrences of a misalignment between the battery and a charging device, a temperature of a portion of a housing, a temperature proximal to the portion of a housing, or a temperature proximal to the battery of the active implantable medical device exceeding a predeterminable threshold, a detected hardware fault of the active implantable medical device, start or completion of a charging session, abort of a charging session, change of a charging rate. The active implantable medical device according to claim 4, wherein the first computer-readable code causes the first processor (3) to automatically identify a misalignment between the battery (2) and a charging device (5) if at least one of the following is detected: i) a number of increase and decrease events of power provided to the battery (2) during a charging cycle exceeds a predeterminable threshold, ii) a rate of increase of a temperature of a housing of the active implantable medical device (1) exceeds a predeterminable threshold, iii) a slope or a morphology of a curve representing a rate of increase of a temperature of a housing of the active implantable medical device (1) deviates from a predeterminable standard configuration by an amount exceeding a predeterminable threshold, and iv) a charging current is lower than a predeterminable threshold. An arrangement (15) comprising a charging device (5) and an active implantable medical device (1) according to any of the preceding claims. The arrangement according to claim 6, wherein the first computer-readable code causes the first processor (3) to transfer the stored battery-related data (9) to the charging device (5), a patient remote device or another external device. The arrangement according to claim 7, wherein the charging device (5), the patient remote device or the other external device comprises a second processor (6) and a second memory unit (7), wherein the second memory unit (7) comprises second computer-readable code that causes the second processor (6) to perform the following steps when executed on the second processor (6): receiving the battery-related data (9) from the active implantable medical device (i); sensing additional charging-related data (13); optionally storing the received battery-related data (9) and/or the additional charging-related data (13) in the second memory unit (7); transferring the received battery-related data (9) together with the additional charging-related data (13) to a remote entity (10; 11) for evaluating the battery-related data (9) and the charging-related data (13). The arrangement according to claim 7, wherein the charging device (5), the patient remote or the other external device comprises a second processor (6) and a second memory unit (7), wherein the second memory unit (7) comprises second computer- readable code that causes the second processor (6) to perform the following steps when executed on the second processor (6): sensing additional charging-related data (13); optionally storing the additional charging-related data (13) in the second memory unit (7); and wherein the second computer-readable code causes the first processor (3) to transfer the stored battery-related data (9) together with the additional charging-related data (13) to a remote entity (10; 11). The arrangement according to claim 8 or 9, wherein the additional charging-related data (13) comprises at least one of a charging status, a charging device status, a charging seeking activity while the charging device is attempting to locate the active implantable medical device, an activation of an implant localization mode, a charging device battery level, a charging device temperature, and data on a power delivery to a charging coil of the charging device. The arrangement according to any of claims 6 to 10, wherein the arrangement (15) comprises a communications unit (10) that serves for receiving data from the active implantable medical device (1) and/or the charging device (5) and for transmitting the data (9, 13) to a remote server (11). A method for improving a battery management of an active implantable medical device (1), the method comprising the following steps: obtaining battery-related data (9) from an active implantable medical device (1); optionally obtaining additional charging-related data (13) from a charging device (5); evaluating the received battery-related data (9) and optionally the received additional charging-related data (13) to identify an event in the battery behavior or charging behavior of the active implantable medical device (1); in case of an identified event in the battery or charging behavior, arranging for at least one of i) training a user of the active implantable medical device (1) and/or of the charging device (5) in an optimized charging process, and ii) providing charging aid hardware to a user of the active implantable medical device (1) and/or of the charging device (5), and iii) replacing the active implantable medical device (1), the charging device (5), or parts of the active implantable medical device (1) or of the charging device (5). The method according to claim 12, wherein the evaluating of the received battery- related data (9) and optionally of the received additional charging-related data (13) is done automatically or by using expert knowledge. The method according to claim 12 or 13, wherein ambient temperature data is additionally evaluated to identify an event in the battery or charging behavior of the active implantable medical device (1).